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Method Statement MS03: Re-vegetation of herbaceous habitat (wetland rehabilitation) 10/12/2020

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Method Statement MS-03:

Method Statement for the re-vegetation of herbaceous wetland habitat within

targeted wetlands for rehabilitation at the ‘Siyaya Plantations Wetland Offset’ site

Method Statement Re-vegetation of herbaceous wetland habitat at the Siyaya Plantations Wetland

Offset site

Description Method statement outlining the procedure for re-instating herbaceous wetland

vegetation at target sites

Reference MS-03

Version 1.1

Revision Number 1

Date 10th December 2020

Author(s) 10.12.2020

Adam Teixeira-Leite (Wetland scientist: Eco-Pulse Consulting)

Location Siyaya Plantations Wetland Offset Site, Mtunzini, KZN

Client Tronox KZN Sands

1. INTRODUCTION

Tronox KZN Sands are required to implement a biodiversity offset as one of the conditions of the

Environmental Authorization (EA) granted for the construction of Fairbreeze Mine. The biodiversity offset

focuses on wetland areas. Eco-Pulse Environmental Consulting Services (‘Eco-Pulse’) developed an

offset management and wetland rehabilitation plan for the Siyaya Plantations Wetland Offset site. Part

of the offset includes the rehabilitation of several degraded wetland areas and detailed wetland

rehabilitation plans have already been compiled for the Siyaya catchment offset site to accomplish this.

Motivation for re-vegetation of areas of wetland:

Many of the wetlands already comprise largely indigenous herbaceous marsh, hygrophilous grassland

and swamp forest vegetation communities, and with the removal of plantation forestry from the

catchment of the wetlands and deactivating artificial drainage, this is likely to support succession. More

mature swamp forest types reflecting reference community types are likely to develop with time, with

the drier forest species and alien plants/weeds likely to be replaced over time by typical obligate

wetland/swamp forest species as a wetter and more natural hydrological regime is established.

It is therefore recommended that natural recolonisation of the wetlands be promoted by observing

natural successional pathways via the native wetland plant species already occurring at the site and

suited to the local conditions. Monitoring is to be undertaken for a period to ensure that adequate re-

growth has occurred and to ensure that alien plants are excluded and managed appropriately at

sufficiently low levels. The addition of burning and biodiversity enhancement planting within herbaceous

marsh and grassland areas (using suitable grasses and sedges) is recommended to steer the course of

succession where appropriate and necessary.

There are also areas of wetland that will be cleared and re-shaped where there are dense alien plant

infestations, an intensive network of artificial drains which will be impractical to simply plug, and in areas

where plantation forestry within the wetland will need to be removed. In these areas to be clear-felled

and/or re-shaped, re-vegetation may become necessary to kick-start plant community succession as

well as to fast-track the establishment of an initial vegetation cover to assist with managing risk of soil

erosion.


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2. PURPOSE OF THE DOCUMENT

The following document sets out a Method Statement (MS) for the re-vegetation of wetland areas

targeted for re-shaping and removal of dense IAPs or plantation forestry from certain wetlands (W06A,

W07, W10, W12, W13 and W14) at the Siyaya Plantations Wetland Offset site. The purpose of the

document is to provide a detailed method statement for the implementation of re-vegetation at

selected sites and to clearly define the roles and responsibilities of the various parties involved.

Project Name Tronox Fairbreeze Mine Biodiversity Offset: Siyaya Plantations Wetlands

Region (Province) KwaZulu-Natal

Wetlands where re-vegetation

of herbaceous wetland habitat

is planned

W06A: 28°58'50.04"S | 31°42'53.51"E

W07: 28°59'5.21"S | 31°42'57.41"E

W10: 28°58'25.09"S | 31°43'25.73"E

W12: 28°58'9.52"S | 31°43'13.72"E

W13: 28°58'49.07"S | 31°43'52.38"E

W14: 29° 0'43.47"S | 31°41'18.18"E

Nearest Town Mtunzini

Owner Tronox KZN Sands

Figure 1. Map showing the location of wetland units where re-vegetation of herbaceous wetland

vegetation is planned.

3. ACCESS TO THE DOCUMENT

A hard copy of this method statement must be available at all re-vegetation sites where work is always

being conducted, at all times.


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4. ASSOCIATED DOCUMENTS

This Method Statement should be read and implemented in conjunction with the following documents:

• Eco-Pulse and GroundTruth, 2020. Wetland Offset Rehabilitation Plan for the Siyaya

PlantationsWetlands, Fairbreeze Mine Biodiversity Offset. Report prepared by Eco-Pulse

Environmental Consulting Services in association with Ground-Truth for Tronox KZN Sands, as part

of the planning phase for the Fairbreeze Mine Biodiversity Offset. February 2020.

• Eco-Pulse, 2020. Construction EMPr for wetland rehabilitation activities at the Siyaya Plantations

Wetland Offset site. Version 1.0 Prepared by Eco-Pulse Environmental Consulting Services for

Tronox KZN Sands. January 2020.

• Eco-Pulse, 2020. Method Statement MS-01: Method Statement for the re-levelling and general

earthworks associated with planned wetland rehabilitation for the wetlands at the Siyaya

Plantations Wetland Offset site. Method statement outlining the procedures for re-levelling and

general bulk earthworks for the rehabilitation of wetlands at the Siyaya Catchment offset site.

January 2020.

• Eco-Pulse, 2020. Method Statement MS-02: Method Statement for for the construction of hard

(concrete) rehabilitation interventions for the wetlands at the Siyaya Plantations Wetland Offset

site. Method statement outlining the procedures for construction of wetland rehabilitation

interventions. January 2020.

5. EXCLUSIONS

Please note that the following is not included in this method statement and is covered in the construction

Environmental Management Programme (CEMPr, Eco-Pulse, January 2020):

• Environmental induction.

• Occupational health and safety issues.

• Fuels, chemical and hazardous

substances management.

• Stockpiling (of materials and waste).

• Waste management.

• Sanitation/ablution facilities.

• Hydrological impacts.

• Erosion and sediment impacts.

• Noise control.

• Vegetation/flora management.

• Wildlife management.

• Fire management.

• Site rehabilitation.

• Heritage resources.

• Monitoring and reporting requirements

6. ROLES & RESPONSIBILITIES

Rehabilitation Officer (Tronox):

• The designated “Rehabilitation Officer” will be responsible for implementing wetland

rehabilitation at the Siyaya catchment offset site in accordance with the Wetland Rehabilitation

Plan for the Siyaya Catchment Wetland Biodiversity Offset (Eco-Pulse and GroundTruth, 2020)

and the Method Statement MS-03 for the Siyaya Catchment: Wetland rehabilitation: Re-

vegetation of herbaceous wetland habitat at the Siyaya Siyaya Plantations Wetland Offset site.

• The Rehabilitation Officer will also be responsible for ensuring that all Contractors involved in the

wetland rehabilitation programme are provided with copies and are familiar with the relevant

Wetland Rehabilitation Plan, CEMPr and all relevant Rehabilitation Method Statements and

implement rehabilitation in accordance with the guidelines and requirements contained therein.

• Undertake regular site inspections in order to monitor compliance with the specifications outlined

in the CEMPr and method statements and provide the contractor with guidance and feedback

where applicable.

• Prepare regular site inspection reports that summarize the findings of the site inspections and

which ensure that the system for implementing the method statement is operating effectively.

• Ensure that the Contractors have received the appropriate environmental awareness training

prior to commencing construction activities.

• Issuing of site instructions to the contractor for corrective actions.


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• May request the Project Manager to suspend part or all the works if the Contractors repeatedly

cause damage to the environment by not adhering to the Wetland Rehabilitation Plan, CEMPr

and/or method statement (i.e. more than 3 significant cases of infringement depending on

severity). The suspension shall be enforced until such time as the offending actions, procedure

or equipment is corrected and the environmental damage repaired.

• Liaising with the wetland ecologist where required.

Contractor(s):

• All Contractors (and Sub-contractors) will be required to comply with all specifications contained

in the CEMPr, design drawings and construction notes contained in the Wetland Rehabilitation

Plan (Eco-Pulse, 2020) as well as this method statement (and any other relevant method

statements).

• Contractors are answerable to the Rehabilitation Officer for non-compliance with the

requirements of the CEMPr, Wetland Rehabilitation Plan and method statement(s).

Resident Engineer:

• Provide day to day support and guidance to the contractor.

• Monitor that the final levels are as per the Wetland Rehabilitation Plan and method statements

(Eco-Pulse, 2020).

• Monitor progress according to a program provided by the contractor.

• Keep a site diary.

• Ensure site instructions are followed.

• Provide feedback to the Rehabilitation Officer and/or Project Manager(s) as requested as well

as on progress (at least twice a week) in the form of photos and summary report.

• Contact the Wetland Ecologist and Rehabilitation Engineer if problems occur on site or if the

contractor is unsure of any task.

• Sign-off on the rehabilitation once levels and earthworks have been undertaken to acceptable

standards as per the rehabilitation plan and method statement(s).

Wetland Ecologist and Rehabilitation Engineer (Eco-Pulse/Ground Truth):

• Provide general oversight and overall supervision for the duration of the contract.

• Issue site instructions.

• Ensure interventions are meeting their objectives.

• Provide telephonic and email support.

• Undertake regular site inspections/ecological monitoring as required.

7. WETLAND RE-VEGETATION METHOD STATEMENT

7.1 Wetland Rehabilitation Interventions

The following rehabilitation interventions are planned for the wetland rehabilitation project at the Siyaya

Plantations Wetland Offset site:

1. Installation of concrete weirs (e.g. drop-inlet weirs, buttress weirs, off-take weirs, slab and drop-

inlet combination weirs).

2. Swamp fig plugs

3. Earth plugs

4. Rock packs

5. Reshaping/re-levelling of targeted wetland areas

6. Removal of roads and backfilling of drains

7. Blocking of existing road culverts

8. Removal of forestry plantation, alien plants and weeds

9. Revegetation of wetlands and terrestrial grassland in surrounding catchment

The location of the individual interventions is as per the applicable maps and tables contained in the

relevant section(s) of the Tronox Fairbreeze Mine Biodiversity Offset: Rehabilitation Plan for the Siyaya

Plantations Wetland Offset (Eco-Pulse and GroundTruth, 2020).


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7.2 Phasing and Timing of Rehabilitation Activities and Work Plan

A work plan for rehabilitation construction activities should be compiled prior to any activities taking

place on site. The timing and phasing of rehabilitation activities should be guided by the following

sequence of works:

1. Site establishment

2. Demarcation of all work areas

3. Alien plant clearing and removal and stockpiling of indigenous vegetation

4. Propagation of wetland plants for re-establishment

5. Initial excavation and stockpiling of wetland topsoil and subgrade

6. Re-shaping of wetlands to re-instate natural topographical profiles

7. Installation of concrete weirs, gabions and earthen structures with appropriate water diversion

and sediment/erosion control measures

8. Preparation of soils for planting

9. Re-vegetation of wetlands according to method statements for targeted habitat types.

The timing of rehabilitation activities will be dependent on the outcomes/timing of receipt of the

appropriate Environmental Authorizations and licenses/permits required for the rehabilitation project

(which will need to be in place prior to any rehabilitation activities taking place). Timing should also take

into account periods of high rainfall when construction activities will be more difficult and risks of failure

higher. Rehabilitation, especially works occurring within river channels, should ideally be restricted to

periods of lower rainfall and avoid undertaking construction during periods of heavy rainfall when flow

volumes and velocities could be high and pose a danger to both the success of implementation of

rehabilitation interventions as well as pose a risk to human health/life.

7.3 General Guidelines & Restrictions

Before the implementation of any of the proposed rehabilitation activities, it is important to understand

the following general site guidelines and restrictions:

i. THE EDUCATION OF FIELD WORKERS IS VERY IMPORTANT as they will be primarily responsible for

undertaking the rehabilitation work.

ii. WORKERS MUST BE STRICTLY MONITORED by a suitably trained site supervisor as they undertake

rehabilitation.

iii. INDIGENOUS VEGETATION MAY NOT BE REMOVED DURING REHABILITATION unless this has been

specifically specified for use in re-vegetation by means of transplanting.

iv. All VEHICLES USED TO ACCESS THE SITE AND TRANSPORT EQUIPMENTN MUST BE RESTRICTED TO

EXISTING DISTURBED AREAS ONLY and should not be permitted to move into undisturbed

vegetation or habitat.

v. BASIC EQUIPMENT REQUIREMENTS: workers must wear the necessary personal protective clothing

(PPE) and use appropriate equipment to do the work. This should include the following where

relevant:

a. Long overalls

b. Eye protection (safety goggles/glasses)

c. Protective gloves

d. Safety boots/gum boots

e. Sun protection hats/caps

f. Drinking water

7.4 Site Setup and Access Control

The following guidelines pertain to the site setup and accessing of wetland areas during rehabilitation:

• The construction camp must be located and established outside of the wetland system and

areas susceptible to potential flooding.

• Existing access roads and tracks should be used to access the site, additional roads through

wetland areas should be avoided where possible.

• All access routes to the construction sites/zones must be identified by the contractor with input

by the wetland ecologist and Environmental Control Officer (ECO) prior to construction

commencing. The access routes must be strictly single lane and must be demarcated.


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• In very wet areas, avoid the use of heavy machinery and make use of foot access using foot

boards to transport materials and equipment to work areas (e.g. along stream lines).

• Wetland areas requiring rehabilitation shall be marked out on a site map (as outlined in the

wetland rehabilitation plan) and demarcated on the ground using suitable pegs, as per the

locality plan/maps contained in the Wetland Rehabilitation Plan for the site. Any sensitive ‘no-

go’ areas must also be demarcated accordingly and access to these areas avoided (e.g. intact

riparian vegetation).

• The location of material stockpile and storage areas, and designated topsoil and subsoil

stockpile areas must be identified with input by the Wetland Ecologist and/or Rehabilitation

Officer prior to construction commencing.

• All areas outside of the demarcated access routes and construction footprint must not be

disturbed and considered 'no-go' areas.

7.5 Methods for Revegetation of Herbaceous Wetlands

There are a number of typical steps to follow when undertaking a re-vegetation project within a wetland

system. These generally include:

Step 1: Setting objectives for the re-vegetation programme

Step 2: Initial planning

Step 3: Plant species selection

Step 4: Selection of method(s) of re-vegetation

Step 5: Preparation of the site

Step 6: Re-vegetation using appropriate techniques/methods

Step 7: Aftercare (maintenance & monitoring)

Step 8: Contingency planning (dealing with risks & uncertainties)

These steps are detailed below.

STEP 1: Setting objectives for the re-vegetation programme

Re-vegetation needs to bear in mind the general objectives of the Wetland Rehabilitation Plan (Eco-

Pulse and GroundTruth, 2020). In line with these objectives, namely establishing suitable wetland

vegetation with biodiversity concerns in mind, the following re-vegetation objectives apply to the Siyaya

catchment wetlands:

• Re-vegetate specific wetland areas once dense IAP infestations, timber plantations and

earthworks/re-shaping has been completed

• Establish an initial indigenous vegetation cover using fast colonizing species that will assist with

binding soils and controlling erosion;

• Use a suitable mix of indigenous wetland plants, including sedges and grasses commonly to the

region and locality;

• Plant wetland species that are common to reference wetlands in the region wherever possible;

• Aim to establish a diverse array of wetland plants (diversity is the key to robustness);

• Where possible, specific species that are important from a biodiversity conservation perspective

are to be planted;

• Employ methods of re-vegetation that have proven successful, efficient and cost effective;

• Adopt an adaptive management approach to re-vegetation that considers monitoring post-

implementation and correcting any problems;

• Re-vegetate areas to create suitable habitat for threatened species (Pickersgill reed frog) using

appropriate indigenous vegetation; and

• Attempt to develop a plant community that will eventually sustain itself naturally in the long-term.

With these objectives in mind, the following key principles have been applied to the re-vegetation plan

for the herbaceous wetlands at the site:


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1. Planting will be based on establishing the best vegetation and habitat cover from a biodiversity

conservation perspective. A range of indigenous plant species will need to be planted to

increase biodiversity benefits and ensure that plant diversity is sufficiently high to provide for a

robust wetland ecosystem. Enhancement planting may be required using rare/endangered

species where possible.

2. Suitable indigenous wetland plants are to be sourced. This will be either from local donor

wetlands or grown at an established nursery on-site or sourced from local nurseries. The origin of

plants must be ensured. By planting eco-sourced native plants this will help to maintain the

unique local characteristics of native plants in the region and these plants will generally have a

greater chance of growing successfully because they are adapted to the local conditions

(Clarkson and Peters, 2012).

3. An adaptive management approach will be adopted. This will help to ensure success of the

project through post-implementation monitoring and maintenance aimed at correcting any

problems.

4. Re-vegetation should begin in areas that are in good condition and proceed towards the most

degraded areas. This will assist in learning about the natural zonation of plants in the wetland and

with planning for the severely degraded areas (Wetland Care Australia, 2008).

5. Plan to retain and improve habitat features in a logical sequence. For example, if an island is to

be created, make sure it is complete before you add fringing plants, because further

construction would disturb the bank (Wetland Care Australia, 2008).

6. Take into account different successional pathways and the implication for designing the planting

plan. The most important quality of vegetation when a site is re-vegetated for biodiversity

purposes is whether the endpoint vegetation is natural. The species that form the matrix of the

desired vegetation type should be planted in combination with some pioneer species if the

successional pathway is known. If a very specific species assemblage is aimed for it is not always

necessary to actively plant or seed all of these. Natural recruitment can usually supplement the

planted vegetation.

7. The desired state of vegetation will need to be defined by the habitat requirements of

endangered fauna (e.g. Pickersgill Reed Frog) that are found within the wetland. Often the

structure of the vegetation is more important in this case than the actual species composition.

8. Adopt best-practice (tried and proven) methods in re-vegetation that take into account species

type, cost and practicalities at the site. In most cases when biodiversity is the only concern for re-

vegetation it is possible to use seeds, which is cheaper than transplants, but this also depends on

the availability of seeds. The advantage of seeding is that a seed mix can be created by mixing

various collected seeds and this seed mix can be used for seeding large areas of the wetland in

a relatively cheap and easy manner. The use of seeding is likely to produce results only if there

are no invaders to be expected or only annuals that will not pose a real threat in the long term.

Also, seeding is not a very attractive option for rare plant species as there will be a waste of seeds

because not all seeds will grow into mature plants. In a small wetland where conditions can be

manipulated to some extent, seeds of rare plants can be used in a seed mix, but the seeds

present in the mix should consist of species that co-occur naturally with the rare species.

STEP 2: Initial planning

Proper planning for the target wetland areas will be critical for ensuring that rehabilitation is successful.

The following aspects are to be considered as part of the initial planning for the wetland re-vegetation

programme:

1. Costing & Capacity

A detailed budget including costing of all re-vegetation activities detailed in this method statement and

equipment costs will need to be compiled prior to any activities occurring.

2. Location of re-vegetation and prioritization of areas

Generally, re-vegetation should begin firstly in areas that are in a relatively good condition and proceed

towards the most degraded areas at the site as this will assist in learning about the natural zonation of

plants in the wetland and with planning for the severely degraded areas (Wetland Care Australia, 2008).

A map showing target areas of Wetland W06A, W07, W10, W12, W13, W14 at the Siyaya catchment offset

site that will be the focus of re-vegetation is included in Figure 1 of this Method Statement.


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3. Prioritization of areas for re-vegetation

It is important that the earthworks and re-vegetation take place from downstream to upstream, so that

the risk of large-scale sediment export from the wetland is reduced. To this effect, it is recommended that

a phased-approach be adopted by targeting downstream habitat units (southern most areas in Figure

1) for earthworks/landscaping firstly and re-vegetating once earthworks have been completed at these

sites before moving on to the next area, working progressively in an upstream/northerly direction.

4. Plant rescue within areas to be excavated

Some areas where re-shaping of wetland is planned may contain patches of indigenous wetland plants

such as reeds, sedges, grasses and bulrushes which can be rescued and used in re-vegetation (i.e.

transplanting of plants). Indigenous wetland plants removed from the site during rehabilitation activities

shall be stockpiled neatly on the periphery of the area being stripped for use in wetland re-vegetation.

Where necessary, wetland vegetation shall be transported to designated wetland vegetation storage

areas. Stockpiled wetland vegetation is to be properly demarcated such that this vegetation is not

unnecessarily disturbed by construction activities. Wetland vegetation should be placed in a shaded

area or covered using an appropriate fabric/tarp to ensure that moisture is retained and to avoid drying-

out. The stockpiled vegetation must be kept moist using some form of spray irrigation on a regular basis

as appropriate and according to weather conditions. No objects are to be placed/stockpiled on top of

wetland vegetation.

There may also species of protected trees (e.g. Ficus trichopoda – Swamp fig) that will need to be

rescued prior to excavating these areas. These trees are small enough that they can be uprooted and

replanted within one of the more intact nearby areas of the wetland along the central riparian zone

outside of areas to be impacted during wetland rehabilitation.

5. Planning site camps and access routes

Careful planning should be undertaken by the designated Rehabilitation Officer prior to any work

commencing at the site. This should include planning the location of any site camps, material storage

areas, refueling sites and access routes which should all be demarcated on a map of the site and

communicated to all workers who will be involved in the rehabilitation programme. Guidelines to inform

this planning may include the following:

• Access to areas should be along existing dirt access roads and vehicles should not be allowed

to move into areas of wetland that are not planned for excavation (access by foot only in these

areas).

• All site camps, storage and refueling areas should be located outside of the wetland boundary

shown in Figure 1.

STEP 3: Plant species selection

The following general rules/guidelines apply to plant species selection for the site:

• Suitable plants for re-vegetation can be selected from the total species pool of ecologically

important wetland species which include mostly perennial species that tend to make up a large

fraction of the biomass in a natural wetland (Russell, 2009). The location of the wetland and the

habitat type are the data requirements that initially inform this selection. Indigenous wetland

plant species locally common to wetlands in the Indian Ocean Coastal Belt Bioregion need to

be selected.

• The form(s) of vegetation and species used should be adapted to the soil and moisture

conditions and use of the area.

• No alien/exotic plants are to be used.

• Opportunistic/invasive indigenous species are to be avoided (e.g. Phragmites australis,

Stenotaphrum secundatum).

• Intended method of planting will affect species selection.

• Rehabilitation objectives will largely dictate species requirements.

• Use plants that are a minimum of 20 cm tall in non-flood prone areas, 30-60 cm tall in flood prone

areas (Wetland Care Australia, 2008).

• Use a mix of ‘fast-growing’ pioneer species and ‘secondary’ climax community species

throughout planting as these will grow at different rates to provide shelter, stability and habitat

during vegetation establishment.


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• Sod-forming grasses are preferred over bunch grasses (Drainage criteria manual).

• Maintenance requirements of individual species should be considered in plant selection

(Drainage criteria manual).

• Rushes and sedges have specific hydrological requirements. The areas in which they will grow

are determined largely by the minimum and maximum water levels. Very few of these plants are

adapted to a static water level (Water and Rivers Commission, 2000).

• Sedges (Cyperus spp.), spikerushes (Eleocharis spp.), bulrushes and rushes (Juncus spp.) are

recommended for riparian and wetland re-vegetation because of their aggressive root systems

(Hoag, 2005).

• A list of priority plants for initial establishment & rationale for selection (e.g. fast establishment /

colonization / good seed source) is provided in Annexure A.

• Recommended that one starts by establishing an interim herbaceous/grass community using

easily-establishing ground cover such as fast growing, stoloniferous annual grasses (e.g.

Stenotaphrum secundatum, Imperata cylindrica, Leersia hexandra, Isolepis spp.).This will serve a

dual purpose of exerting a competitive influence, thereby inhibiting alien seed recruitment, and

stabilizing the bare soil until the natural climax community has established itself It is anticipated

that, with the return of a more evenly distributed hydrological regime, indigenous wetland

grasses, reeds and sedges will naturally colonise the rehabilitated area.

• It would be advisable to plant at the onset of the wet season (early spring – August to October)

so that watering requirements are minimal.

• Mono-specific planting should be avoided as diversity is the key to robustness, which will assist in

retaining sediment and preventing erosion.

• At least two-thirds of plants should be sedge species.

• Temporary wetland areas can be planted to hygrophilous grassland with other sedges.

• Enrichment planting: spot plant/seed other interesting species to add diversity (such as Kniphofia,

Dissotis, etc). Opportunities exist for introducing rare/threatened species, such as establishing

endangered Red Hot Poker plants (e.g. Kniphofia littoralis and Kniphofia pauciflora) amongst

shorter growing wetland sedges. See also Nichols (2005): Growing Rare Plants: a practical

handbook on propagating the threatened plants of Southern Africa. This document is currently

out of print but can be downloaded in PDF format online at:

www.sanbi.org/node/2109/reference

STEP 4: Selecting the best method(s) for re-vegetation

For many wetland systems, once the natural hydrology of the system has been re-instated, wetland

vegetation is likely to re-establish itself naturally through natural recruitment by indigenous species and

the planting of vegetation will generally not be necessary (Russell, 2009). However, given that a number

of sites will be targeted for re-shaping and removal of forestry and dense alien plant infestation from

wetlands, active planting will assist in accelerating natural successional processes in these areas, as well

as ensure vegetation cover establishes to prevent soil erosion once these interventions have been

implemented.

Active re-vegetation of key areas of selected wetlands at the Siyaya catchment offset site has therefore

been selected and refers to the manual planting/seeding of vegetation within a wetland. There are

generally three main methods for establishing plants in a wetland through active re-vegetation. These

include: (1) seeding, (2) cuttings (plant parts that can grow a new plant or clone), and (3) transplants

(establishing whole plants). The method of planting is dependent on a number of aspects, including:

• the species chosen for planting and their specific planting method requirements;

• the availability of seed/plant material from adjacent sites/nurseries;

• the cost of implementation; and

• practical limitations at the site.

A combination of planting whole plants/plant materials from donor wetlands and nurseries as well as the

harvesting of seeds from donor sites and nurseries is chosen for this project to allow for flexibility in the

planting method and to assist with ensuring that as diverse an array of wetland plants as possible are

sourced and used in re-vegetation. In this regard, it will be important that plants are ready and available

well in advance and having these available for rehabilitation of the wetland as soon as earthworks are

complete (this may mean growing plants on-site prior to rehabilitation commencing). It is recommended

that a portion of one of the wetlands be used as an on-site nursery but also consider using outside sources

(list with contact details to be provided).


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STEP 5: Preparation of the site prior to planting/seeding

Prior to commencing with planting/seeding, it is important that the wetland site is adequately prepared

in advance. The following guidelines apply:

• Once earthworks, engineering structures and final shaping has been completed, wetland

vegetation is to be reinstated as soon as weather conditions allow for plant growth.

• In general, fertilizer is not necessary nor is it recommended for wetland re-vegetation (particularly

in wetlands that have inherently lower nutrient levels, as this may promote increased weed

growth). If good topsoil exists at the site, then no specific preparation is likely to be required.

However, in areas where loss of topsoil has taken place, fertilizer application may be required.

Where it is suspected that the soil may be poor it is useful to undertake testing of the soil nutrient

status and liming requirements. If lime and fertilizers are to be used these must be incorporated

into the soil at least two months before planting, except for nitrogen fertilizer that should be

applied at the time of planting (Russell, 2009).

• Soils should also be moist and as weed-free as possible.

• Should the area be invaded by weeds/alien plants, these must be removed prior to planting

using appropriate control methods for particular species.

• For seeding, the soil needs to be prepared to optimise germination. This is typically undertaken

by hand hoeing to loosen the soil in the seedbed but should be firm enough to facilitate good

contact between the seeds and the soil.

• Where significant soil compaction has occurred, the soil may need to be ripped in order to

reduce the bulk density of the soil such that vegetation can become established at the site.

• A weed-free mulch is recommended to help retain moisture for germination. Mulch should be

crimped in if possible, to limit floatation if flooding is likely to occur. It is very important that mulch

not be derived from stands of invasive exotic species or weeds.

STEP 6: Re-vegetation of the site using appropriate techniques

6-1 Direct seeding of wetlands

In non-flowing or low energy wetland systems, direct seeding is often the most cost-effective method

of re-vegetation (Water and Rivers Commission, 2000).

Step 1: Identify and collect seed from local sources.

• Seed can be collected from donor wetland sites or commercially grown wetland plants.

• Thatching is a method of seeding that can be used with grasses or sedges that uses ripened

seeds as they are still attached to the stems, which are cut from the plants. Stems with mature

inflorescences should be collected and deposited on the rehabilitation site.

Step 2: Preparation wetland site for seeding.

• For seeding, the soil needs to be prepared to optimise germination.

• This is typically undertaken by hand hoeing to loosen the soil in the seedbed but should be

firm enough to facilitate good contact between the seeds and the soil.

• If topsoil and native seed mixes are used, fertilizer is often not needed (Drainage criteria

manual).

Step 3: Apply seed to the wetland.

• Seed mixtures should be sown at the proper time of year specified for the mixture.

• The seed is spread manually (broadcast) over the wetland or can be planted in rows either

by hand or using a precision planter.

• The seeding rate (seed used in kg/ha) varies according to the method and the type of seed

being used. A good rule of thumb is to use twice the amount of seed used for row planting

when broadcasting.

• The amount of seed to be used must also be modified for areas that are not irrigated or do

not have a regular supply of moisture. An increase of 20% in seeding rate is recommended for

most dryland (non-irrigated) establishment (Russell, 2009). The higher density for wetland seed

is also in part to compensate for the higher seed mortality inherent with smaller seed sizes

• Generally, the small-seeded sedges, rushes, grasses and forbs should be placed on the soil

surface as they require light to germinate, whilst the larger-seeded species can be buried a

deeper and may prefer to be buried (Jacobson, 2006).


11

• The seed should be planted no deeper than 2.5 times the width of the seed but never left lying

on the surface of the soil. The more sandy a soil, the deeper the seed should be planted and

the more rich in clay a soil is, the shallower the seed should be sown (within the above limits)

• When broadcasting seed it is necessary to lightly cover the seed with soil by hand raking the

seed into the soil. This is best done by raking. Once the seed has been planted the area must

be rolled to ensure the seed has good contact with the soil. This can be done in large areas

with a Cambridge roller or with a partly filled plastic water drum in smaller areas.

• Avoid sowing or thatching in areas where runoff concentrates.

• All planted areas should be mulched preferably immediately following planting, but in no later

than 14 days from planting. Mulch conserves water and reduces erosion. The most common

type of mulch used is hay or grass that is crimped into the soil to hold it.

• Hydroseeding is also an option which utilizes equipment capable of shooting seed some

distance

Step 4: Weed control.

• Thorough weed control is essential for this method to be successful, as germinating native

seedlings tend to be out-competed by faster growing introduced species.

6-2 Seedbank collection from donor wetlands for use in re-vegetation

Many wetland species have seeds that live for several years stored in the “seed bank” which contains

dormant seeds from previous seasons within the sediment/soil of the wetland (Brock & Casanova,

2000). The collection of seed bank material from donor wetlands can be used to re-vegetate the

wetlands using the following technique:

Step 1: Select a suitable donor wetland.

• Select a nearby wetland that is well-vegetated with herbaceous wetland that is characteristic

of the region.

• If a donor wetland site is to be used, there must be sufficient sites where it is safe to remove

seedbank material without seriously damaging the donor wetland.

Step 2: Determine the volume of seed bank needed for re-vegetation purposes.

• Two or three 10 litre buckets of seed bank material will be sufficient for 20 lines each 10 m long

and 0.1 m wide (Brock & Casanova, 2000).

Step 3: Harvest seedbank material from the donor wetland.

• Move through the wetland, digging up a bucket of soil at a site then moving to a spot a metre

away before repeating.

• Locate harvesting sites in a mosaic (or chess board) pattern and harvest about 0.5m² for every

10m² or 5% of total area (Russell, 2009).

• Harvesting of seed must be done with caution so as not to unduly disturb the donor wetland.

• Soil from within stream channels, flow concentration zones or in any other areas susceptible

to erosion should not be harvested.

Step 4: Mix soil from donor wetland.

• Spread the soil containing the seed bank from the donor wetland out on a large plastic sheet

and mix well.

• Mixing the soil taken from the different wetness zones at the donor site means that wherever

you eventually put the seed bank, all species have an opportunity to establish. This is a useful

strategy when you don’t know how water levels will vary over time in the candidate wetland.

Step 5: Break seed dormancy (where applicable).

• Seed may have dormancy mechanisms that need to be broken, for example through

drying/heating/chilling.

• An alternative is to use a plant hormone to artificially break dormancy.

Step 6: Use seedbank material from donor site to re-vegetate candidate wetland.

• Spread the soil containing seed bank material in lines perpendicular to the direction of flow

and at least a couple of metres apart.

• Spreading the seed bank down the slope will allow all species the chance of establishing,

especially if water levels fluctuate in the wetland.


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6-3 Transplanting growing plants from donor wetlands/nurseries

Some species of wetland plants may be difficult to obtain except through transplanting whilst others

which are rapid rhizome spreaders are easier to propagate by division than seedlings (Water and

Rivers Commission, 2000). Live plants are used to establish emergent aquatic vegetation in shallow

open water, deep marsh and shallow marsh zones because seed is difficult to establish in these “wet”

zones. Working with whole/growing plants does require a systematic approach, however (Russell,

2009). The timing of transplanting is best done shortly before or at the beginning of the growing season

and material for transplants can originate from a commercial nursery or it can be taken from a donor

site within the same wetland or an adjacent/nearby wetland. Established plants are collected from

the donor wetland in a similar manner to the collection of seed bank material.

Step 1: Select a suitable donor wetland/nursery.

• Select a nearby wetland that is well-vegetated with herbaceous wetland that is characteristic

of the region.

• If a donor wetland site is to be used, there must be sufficient sites where it is safe to remove

plants without seriously damaging the donor wetland (Russell, 2009).

• If there are not enough suitable donor wetland sites available, plants from a nursery will need

to be sourced. The challenge here is that few wetland species are commercially grown.

• It is critically important to consider the genetic origin of the plants used since local strains are

preferable. It is therefore best to use small regional nurseries that breed plants from the region,

instead of large commercial nurseries that are likely to obtain stock from large regional

suppliers. Information about whether the plants are terrestrial, amphibious or submerged

species will need to be obtained. Also check where the plants will establish best in relation to

water level, and the ideal planting depth for each species

• The best way to ensure that plant material is available for rehabilitation sites is to establish

small-scale regional nurseries.

• Pre-vegetated products need to be pre-grown for about five weeks during the spring and

early summer to ensure that the seedlings are already established before planting.

Step 2: Harvesting plants from donor sites.

• The timing of transplanting is best done shortly before or at the beginning of the growing

season (spring, early summer).

• Locate harvesting sites in a mosaic (or chess board) pattern and harvest about 0.5m² for every

10m² or 5% of total area (Russell, 2009).

• Harvesting of plants must be done with caution so as not to unduly disturb the donor wetland.

• Move through the wetland, digging up plants at a site then moving to a spot a metre away

before repeating.

• For whole/growing plants, ensure that plants are dug up with as much of their roots intact and

such that the soil around the roots is not disturbed (i.e. intact root ball).

• Keep each group of plants separately and note the approximate water depth where

collected.

• Material from within stream channels, flow concentration zones or in any other areas

susceptible to erosion should not be targeted for plant harvesting.

• Care also needs to be taken that weeds/alien plants are not transplanted with the donor

plants.

• Prevent collected plants from drying out by placing them in the shade in damp sacks/bags

or damp newspaper.

• If adequate time is not provided there is a risk that slower germinating species will drown if

they are inundated at too early in their life stage (Jacobson, 2006).

Step 4: Transplanting of live plants.

• Collected plants should be replanted as quickly as possible following removal (i.e. within a

day or two of harvesting).

• Large clumps of plants can be carefully separated into smaller clumps or into several

individual stems with attached roots, known as slips.

• A recommended approximate planting density of 1–3 plants per m2 generally applies to

wetlands (Clarkson and Peters, 2012).

• The spacing between plantings will vary according to their type (woody vs herbaceous), but

as a general rule it should mimic that found under natural conditions at the donor site. Closely-

spaced plantings are preferred to encourage rapid canopy growth, especially in areas of

intense weed competition in the wet tropics (Jacobson, 2006). Plant spacing also depends


13

on the type of plant chosen and its purpose. For vegetated sills, a spacing of 100 to 200mm

(within and between rows) is recommended, while a spacing of 500mm within rows is

recommended and from 500 mm to 1000 mm between rows for simple re-vegetation

operations. Species installed as live plants in clusters or pre-vegetated mats will frequently

spread quickly either from rhizomes or from seed. Therefore, it is not necessary to saturate an

entire site with live plants (Jacobson, 2006). When using vegetation plugs, the spacing of plugs

should not be too wide. Planting should be done in patches rather than wider spacing. Hoag

(2005) recommends a spacing of 46-50cm centres in patches that are about 3m2 spaced

about 3m apart. Over time the plants will then spread from the planted areas into adjoining

unplanted parts of the wetland, particularly along water flow paths.

• The plants should be planted with their roots in as much of the original soil medium as possible

from which they were removed and in a water depth similar to that where they were

collected.

• Plants in general must be planted with their tops out of the water or they will die.

• When planting the material, dig a hole in the soil deep enough to ensure that the roots do not

bend upwards.

• The bottom of the root ball should be in contact with the saturation zone (Hoag, 2005).

• The soil around the plant should be firmly compacted.

• Trim the leaves back of large plants to about 10 to 15cm in length, so as to reduce water losses

through transpiration.

Step 5: Securing new vegetation.

• Vegetation that has very recently been planted is generally susceptible to being washed

away until it has become well established, particularly in areas of permanent water flow or

high-energy environments.

• The plants should be secured using a coarse mesh (steel wire or plastic) and/or a fine

biodegradable mat placed over the vegetation to secure the plants while they become

established.

• The plants must be able to grow unhindered through the mesh or mat.

• Biodegradable fibre mats may be placed on the soil surface to protect the soil from erosion

and will generally decompose by the time the vegetation has become well established. Mats

can be staked down or held down with timber batons tied down using duckbill anchors.

• Planting can also be done into holes punched in sisal bags filled with soil and buried, or into

ecologs.

6-4 Using cuttings from donor wetland plants

As opposed to using whole live plants from donor sites, cuttings refers to plant propagules or vegetative

material such as rhizomes and stolons harvested from plants that can then be used to grow new plants.

• Cuttings should be made from healthy and vigorously growing plants and should preferably

be treated with dilute disinfectant to prevent the spread of plant diseases.

• A cutting should include at least two to three nodes since this is where the tissues are located

from which new growth takes place. This also applies to rhizomes and stolons.

• It should be noted that not all species are suitable for growth from cuttings and it is advisable

to start growth from cuttings in a nursery where the young plants can be monitored. Only

transplant into a wetland when the cutting is fully rooted and new growth is visible.

• The cutting should be planted to a depth of about 50mm and the soil around the propagule

must be lightly compacted to ensure good contact between the soil and plant matter. If

possible, leave about 25 to 50mm of herbage above the ground level.

• Refer also to Nichols (2005): Growing Rare Plants: a practical handbook on propagating the

threatened plants of Southern Africa for methods and techniques for growing rare plants. This document

is currently out of print but can be downloaded in PDF format online at:

www.sanbi.org/node/2109/reference

Special guidance regarding the collection of indigenous plants/seed:

• Collection /harvesting of indigenous plants (whole plants, plant material or seed) may only take place

with the appropriate permits from Ezemvelo KZN Wildlife and with permission from the landowner on which

donor wetlands occur.


14

• Use individuals of local species taken from surrounding areas, in order to avoid or reduce genetic pollution.

Collection of plant material should be well-documented (locality specifically) such that plant origins are

known.

• Plant/seed collection should be undertaken under the strict supervision of a qualified botanist who is able

to recognize the various wetland plant species in the field.

• Collection should limit habitat destruction by implementing a “mosaic collection” method to ensure

limited disturbance and adequate recovery of the donor site.

• Wetland plant harvesting should be sustainable by ensuring that plants can still recover where cuttings

are taken and that at least 50% of seeding material is retained to allow plants to complete their life-cycles

(Kerry Seppings, 2011).

• Whole plants should not be removed from donor wetlands (except from rescue sites – see comment

below).

• Alien/invasive species may not be used for re-vegetation purposes.

• Indigenous woody species are to be planted only along channeled riparian sections as they are likely to

impede the expansion of non-woody or herbaceous plants.

• Many of the Red Hot Poker plant species (Kniphofia spp.) can be difficult to differentiate and many of the

cultivated plants are hybrids varieties. Therefore, only Kniphofia species of known identity and origin may

be considered as unknown species or where the genetic origin of species is unknown can easily hybridize

with other species and result in the contamination of genetic material (Kerry Seppings, 2011).

STEP 7: Aftercare – maintenance & monitoring

It is crucial to follow up and check on the condition of the re-established vegetation cover and to assess

the particular aftercare requirements (Russell, 2009). Vegetation planted for rehabilitation requires a lot

of attention after it has been planted, especially in the first few months of establishment. This is especially

important for establishing native species since it may take several years for vegetation to become

properly established. Typical aftercare measures will need to include:

• In the first two years after planting, the site may require: weeding, watering, water retention

products, protection from pests, replacing dead plants, top-dressing in sandy/loam soils to

promote lateral root growth of plants in flood-prone areas (Wetland Care Australia, 2008).

• The area where seeds or plants have been sown/planted must be kept moist through

emergence and the first weeks thereafter, which may necessitate watering or irrigation. If

required, nitrogen fertilizer should be applied just prior to irrigation. The amount of watering

required is determined by the specific planting material used, the specific characteristics of the

site and the rainfall conditions following planting. It is generally wisest to plant at the onset of the

wet season so that watering requirements are minimal. A guideline for watering in areas that

tend to drain quickly is to provide water at least twice a week. When watering, only wet the soil

as deep as the plant rooting depth and spray the water on at a rate that will be low enough not

to cause runoff (Russell, 2009).

• Alien plant/weed control will need to be undertaken in accordance with the Alien Plant

Management Strategy (still to be compiled) which will be developed for the Siyaya Catchment

Offset site (it will deal with alien/weed infestations using appropriate physical, chemical or

biological methods). The selective remove of weeds and other undesirable plants should be

undertaken in order to maintain the desired vegetation community composition.

• Management during the establishment year is important to ensure that the plants don’t receive

too much water or too little. Keep a record of any plant losses and the possible reasons why they

may have died. For example, if a portion of the site appears to be too wet for selected plants to

grow, the intolerant species should be replaced by a more water-tolerant plant species. This is

particularly important in the case of vegetation sills established across the flow of water, as these

gaps may serve as points of weakness where flow is concentrated.

• The wetlands will need to be routinely inspected/monitored following planting to ensure that the

rehabilitation objectives are being met and to identify and implement necessary follow-up

measures to increase success of re-vegetation. Monitoring the planting for 3-5 years after the

establishment year should be undertaken according to Hoag (2005). The identification of

problems during the rehabilitation process through regular site monitoring (e.g. weed infestation,

over-seeding, failure of seed to germinate, etc.) and immediate remedial action can often be

key in preventing major problems later on in the project.


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STEP 8: Contingency planning – dealing with risks & uncertainties

Dealing with risks and uncertainties is part and parcel of a wetland re-vegetation programme. Some of

the risks and uncertainties that are likely to manifest themselves may include the following:

• Usually the wetland is going to be too wet to get heavier equipment into; therefore,

broadcasting seed with smaller equipment or even hand-held equipment will be necessary

(Jacobson, 2006).

• Unexpected problems may arise during re-vegetation (e.g. the site may be wetter or drier than

anticipated). Some of these uncertainties and risks can be avoided by planting a diversity of

plants that can grow under a wide range of conditions (ERO Resources Corporation, 1997).

• Where collections of plants/seed are made from a weed infested area, there is a good chance

that weed seeds could be transported in the soil (Hoag, 2005).

• Mulch at the edge of the wetland, or buffers (logs or rocks) which reduce water movement can

also encourage wetland plant establishment. It may be best to establish plants when water levels

are low in some instances (Brock & Casanova, 2000).

• Direct seeding can be unpredictable, especially in very wet conditions. If the wetland is subject

to surface water flow, seeds may be washed away to germinate elsewhere than desired.

• Seedlings of species such as Juncus can stay small for a relatively long time and are therefore

susceptible to competition from weeds/alien plants.

7.6 Approval and Signing Off

The wetland revegetation must be inspected by the Wetland Ecologist and signed off by the

rehabilitation officer after completion, unless agreed to otherwise.

7.7 Environmental Management Guidelines

Guidelines for managing potential environmental impacts associated with the planned wetland

rehabilitation and re-levelling/earthworks is covered in the Construction Environmental Management

Programme (CEMPr) for wetland rehabilitation activities at the Siyaya catchment biodiversity offset site

(Eco-Pulse Consulting, 2020). This contains a range of environmental management requirements and

guidelines/recommendations in terms of managing potential risks associated with the various phases of

the rehabilitation project, including waste management and pollution control, access control,

avoiding/minimizing disturbance to sensitive areas, materials and stockpiles management, water use,

wildlife management, erosion and sedimentation, etc. and also includes guidelines for monitoring

impacts and gauging the success of impact mitigation/management measures.

The Construction EMPr will therefore need to be read carefully in conjunction with this rehabilitation

method statement and implemented appropriately.

7.8 General Health and Safety Guidelines

The following occupational health and safety guidelines generally apply to construction activities

associated with wetland rehabilitation and will need to be complied with where relevant to the site:

• All site workers to undergo specific safety training before undertaking this work so that they are

aware of the various risks and measures to be taken in emergency situations

• Each project manager and contractor shall have a copy of the Occupational Health and Safety

Act No. 85 of 1993 (OHS). All relevant OHS standards will be fully implemented.

• An adequately equipped first aid kit shall be easily accessible at all work areas and needs to be

kept fully stocked. All first aid treatment and usage shall be recorded. The first aid kit shall be

under control of a trained and competent first aid officer.

• PPE (Personal Protective Equipment) prescribed in the agreement between the rehabilitation

implementer and contractor shall be worn at all times during work. PPE shall meet the minimum


16

prescribed standards of quality (SABS approved). PPE shall be replaced when it becomes

ineffective through wear and tear.

• Workers should be encouraged not to drink water directly from any wetland or watercourse and

suitable drinking water in adequate quantities will need to be provided to workers.

• Project managers and contractors will need to be sensitive to the potential dangers of floods

when working in wetland areas. Rainfall in the catchment above the wetland, and flow within

the wetland should be visually monitored by project managers and contractors. In high rainfall

events where there is an increased risk of flash floods, work should ideally cease within wetland

areas to limit risks to personnel, equipment and the environment.

• All vehicles (including trailers) used shall comply with all legal requirements in terms of

roadworthiness and licensing. Daily pre-trip vehicle checks should be done and recorded by the

driver on a suitable checklist. Trailers also form part of the daily checklist. Any faults affecting the

roadworthiness of the vehicle shall be repaired immediately or alternative transport used.

Vehicles used for transporting workers shall have suitable passenger facilities.

• All hand tools and machinery is to be suited to the nature of the work and are to be maintained

in safe working order.

• All machinery will need to have the required safety guards to enclose dangerous working parts.


17

8. REFERENCES

Armstrong A, 2009. WET-Legal: Wetland rehabilitation and the law in South Africa. WRC Report No.TT

338/09. Water Research Commission, Pretoria.

Brock, M.A. and Casanova, M.T., 2000. Are there plants in your wetland: Revegetating wetlands.

LWRRDC, UNE, DLWC and EA.

Clarkson, B. and Peters, M., 2012. Wetland Restoration: A handbook for New Zealand Freshwater Systems.

Chapter 10: Revegetation. NSW Murray Wetlands Working Group Inc., Albury NSW.

DRAINAGE CRITERIA MANUAL (V. 2) REVEGETATION 06/2001 1993. Design Workbook for Establishment of

Natural Vegetation. Denver, CO: Urban Drainage and Flood Control District.

DWAF (Department of Water affairs and Forestry). 2005. A practical field procedure for identification and

delineation of wetland and riparian areas. Edition 1, September 2005. DWAF, Pretoria.

Eco-Pulse and GroundTruth, 2020. Wetland Offset Rehabilitation Plan for the Siyaya Plantations Wetlands,

Fairbreeze Mine Biodiversity Offset. Report prepared by Eco-Pulse Environmental Consulting Services in

association with Ground-Truth for Tronox KZN Sands, as part of the planning phase for the Fairbreeze Mine

Biodiversity Offset. January 2020.

Eco-Pulse, 2020. Construction EMPr for wetland rehabilitation activities at the Siyaya Plantations Wetland

Offset site. Version 1.0 Prepared by Eco-Pulse Environmental Consulting Services for Tronox KZN Sands.

January 2020.

ERO Resources Corporation, 1997. City of boulder: Wetland Protection Program Best Practices:

Revegetation Rules. Wetland publication series No. 6. First Edition.

FERC, 2011. Revegetation and wetlands management plan: Condit Hydroelectric Project

Decommissioning. Project No. 2342. 14 March 2011.

Hoag, J.C., 2005. Wetland Revegetation Planning. Technical Notes: Plant Material. U.S. Department of

Agriculture: Natural Resources Conservation Service. Spokane, Washington. February 2005.

Jacobson, R.L., 2006. Restoring & Managing Native Wetland & Upland Vegetation. Minnesota Board of

Soil & Water Resources Minnesota Department of Transportation. January 2006.

Kerry Seppings Environmental Management Specialists, 2011. DTP/KSIA: Restoration & Rehabilitation

Report 2. Pre–Implementation, Wetland Rehabilitation and Priority Area Action Plan. Post Review Version

1. March 2011.

Macfarlane, D.M., Kotze, D.C., Ellery, W.N., Walters, D., Koopman, V., Goodman, P. & Goge, C. 2008.

WET-Health: A technique for rapidly assessing wetland health, Version 2.

Nichols, G. R., 2005. Growing Rare Plants: a practical handbook on propagating the threatened plants

of Southern Africa. Southern African Botanical Diversity Network, Report No. 36. SABONET, Pretoria.

Available online at www.sanbi.org/node/2109/reference

Russell, W.B., 2009. WET-Rehab Methods: National guidelines and methods for wetland rehabilitation.

WRC Report No. TT 341/09. Water Research Commission, Pretoria.

Water and Rivers Commission, 2000. Using rushes and sedges in revegetation of wetland areas in the

south west of WA, Water and Rivers Commission, River Restoration. Report No. RR 8.

Wetland Care Australia, 2008. Wetland Rehabilitation Guidelines for the Great Barrier Reef catchment.

Compiled for Department of the Environment, Water, Heritage and the Arts.


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ANNEXURE A: List of selected herbaceous wetland plants for re-vegetation

purposes

A list of wetland plants species with details regarding habitat preference, establishment qualities, etc. has been

provided below to guide wetland re-vegetation activities at the Siyaya Catchment Offset Site wetlands. An effort

should be made to ensure that at least 30 % of all plantings in wetland areas are of species in the family Cyperaceae

(i.e. sedges), but up to 50% can be attained, depending on plant availability. This list is not meant to be exhaustive

and may be reassessed during the course of rehabilitation work as necessary.

Plant list 1: Permanent – Submerged/floating marsh planting zone

Family Botanical Name Common Name(s) Requirements

Dicotyledons Nymphae nouchali Blue water lily Open water habitats (floating marsh)

Menyanthaceae Nymphoides indica Small waterlily Open water habitats (floating marsh)

Monocotyledons Potamogeton crispus Wavy-leaved Pondweed

Submerged aquatic

Monocotyledons Potamogeton schweinfurthii Pondweed Submerged aquatic

Monocotyledons Potamogeton thunbergii Broad-leaved Pondweed

Submerged aquatic

Plant list 2: Permanent – emergent planting zone


Cyperacae Carex cognata Nodding sedge Open vleis and riverine situations where underground organs are kept permanently wet

Cyperacae Cyperus denudatus var. denudatus

Winged sedge Permanent water of swamps and stream banks, less frequently in wet depressions in grassland

Cyperacae Cyperus dives Giant sedge Reed swamps, moist depressions, riverbanks and streamlet margins

Cyperacae Cyperus involucratus Wetlands, swamp forests, river margins, sometimes considered a northern form of C. textilis

Cyperacae Cyperus latifolius Freshwater swamps and along river and streamlet margins and in local wet depressions in grassland

Cyperacae Cyperus prolifer Dwarf papyrus Permanent marshes, seaonal pools, does not tolerate stagnant conditions or shading

Poacaea Echinochloa pyrimidalis Mat forming grass, wetland permanent

Cyperacae Eleocharis limosa Finger rush Damp waterlogged marshes and dams

Cyperacae Fimbristylis complanata Flattened rush Margins of pools and seasonally wet areas

Cyperacae Fimbristylis ferruginea Wet habitats along the coast and up rivers

Commelinaceae Floscopa glomerata Along streams, in water

Cyperacae Fuirena ecklonii In permanent water of shallow streamlets, seeps or vleis

Poacaea Hemarthria altissima Red swamp grass Always in wet places, can tolerate prolonged periods of dryness

Cyperacae Isolepis fluitans Vleis and drainage canals and ditches, extending into softly flowing water


19


Juncacae Juncus kraussii subsp. kraussii iNcema Full sun, brackish marshy areas generally

Juncacae Juncus lomatophyllus Full sun, permanently wet areas

Juncacae Juncus oxycarpus Very wet swamps and shallow water

Juncacae Juncus punctorius Permanent wet places and sometime shallow water

Liliaceae Kniphofia linearifolia Common marsh poker

Marshy areas, stream banks, full sun

Liliaceae Kniphofia littoralis Red hot poker Marshy coastal areas, full sun

Poacaea Leersia hexandra Wild rice grass Floodplains, marshes, vleis

Polygonaceae Persicaria attenuata Bristly Snakeroot Moist areas near swamps

Cyperacae Rhynchospora barrosiana Gently moving water of open vleis and streamlet banks, or in very wet soil

Cyperacae Rhynchospora holoschoenoides Wet and very moist situations on sand

Cyperacae Schoenoplectus scirpoides Wand sedge Coastal marshy areas, edges of ponds

Cyperacae Scleria angusta Swamp forest: shade or partial shade

Cyperacae Scleria distans Permanently wet areas, usually on sand

Cyperacae Scleria dregeana Permanent vleis, marshy ground and stream banks

Cyperacae Scleria melanomphala Forms stands in permanently wet, open areas

Plant list 3: Semi-Permanent planting zone


Anthericaceae Chlorophytum krookianum Giant Chlorophytum

Damp areas in grassland, swamps and forest margins

Asteraceae Cotula nigellifolia Staggers weed Edges of open water

Cyperacae Cyperus articulatus Jointed flat sedge Wet, organically rich sediments at edges of pans, in sand and alluvium along river banks, or coastal swamps, pioneer plant

Cyperacae Cyperus digitatus In or near water in swamps and seasonally flooded areas

Cyperacae Cyperus fastigiatus In vleis in permanent water, or towards the margins where periodically inundated

Cyperacae Cyperus laevigatus Rivierkweek Early colonizer of sandy alluvium

Cyperacae Cyperus natalensis Full sun, wetland edges and permanent fresh water up to 1m depth

Cyperacae Cyperus sensilis Loamy substrates with a high organic content and plentiful water (usually the margins of swamps and streamlets)

Cyperacae Cyperus sexangularis Margins or rivers or streams and localized wet areas, occasionally found in drier areas

Cyperacae Cyperus sphaerospermus Moist alluvium along margins of swamps and streamlets, often in pure stands

Cyperacae Cyperus textilis Tall mat sedge Swampland and along rivers and streamlets, sometimes considered a southern variant of C. involucratus

Fabaceae Derris trifoliata Coastal thicket, along rivers, mangrove swamps

Cyperacae Fuirena hirsuta Damp to wet situations, favouring riverine fringes and sandy substrate


20


Cyperacae Fuirena obcordata Growing in shallow water or in very wet swamps, usually in a sandy, organically rich substrate

Cyperacae Fuirena pachyrrhiza Margins of vleis and near streams, often amongst shrubs fringing small patches of trees, where the continuity of forest has been disturbed

Poacaea Imperata cylindrica Cotton wool grass Poorly drained, seasonally flooded, moist, non-saline coastal areas

Cyperacae Isolepis costata Stream banks or vlei margins with silted verges

Cyperacae Isolepis prolifer Bare sands or sandy alluvium where there is some accumulation of water, pioneer of disturbed wetlands sedge for damp edges forms a neat mat of foliage

Juncacae Juncus dregeanus Edges of rivers, marshes, seasonally flooded areas, always growing amongst hygrophilous grasses

Juncacae Juncus effusus Soft rush Swamps, rivers, often forming large dense stands around permanently wet places

Liliaceae Kniphofia pauciflora Dainty poker Waters edge, marshy grassland

Liliaceae Kniphofia rooperi Winter Poker Marshy coastal areas, full sun

Cyperacae Kyllinga melanosperma Forming dense conspicuous clumps/stands along streamlet margins, always near water

Cyperacae Lipocarpha chinensis Streamlet margins or very damp mud on fringes of drainage channels

Onagraceae Ludwigia adscendens Floating edge plant

Polygonaceae Persicaria senegalensis Silver snake root Edge plant of moist habitats

Polygonaceae Persicaria serrulata Knotweed/ Snakeroot

Edge plant, damp areas

Cyperacae Pycreus mundii Swamp and slow moving streams

Cyperacae Pycreus nitidus Margins of swamps, streamlets, permanent pools

Cyperacae Pycreus permutatus Vleis

Cyperacae Pycreus unioloides Vleis with permanent water or very wet depressions in moist grassland

Cyperacae Rhynchospora brownii Stream margins and edges of vleis

Cyperacae Rhynchospora spectabilis Wet marshy grasslands

Cyperacae Schoenoplectus corymbosus Margins of dams and rivers

Cyperacae Scleria achtenii Damp to wet habitats precursory to forest

Cyperacae Scleria natalensis Forms almost pure stands in semi-shade in wet or seepage areas

Thelypteridaceae Thelypteris interruptus Hottentot's fern Permanent and seasonal swamps

Xyridaceae Xyris capensis Yellow-eyed grass Open wet areas and seeps

Liliaceae Zantedeschia aethiopica White Arum lily Sun or shade in marshy areas

Plant list 4: Seasonal planting zone


Apiaceae Berula erecta Toothache root Marshy areas, on stream banks

Gentianaceae Chironia palustris Marsh Chironia Marshy areas near rivers

Amaryllidaceae Crinum macowanii River lily Damp areas - seasonal zone

Scrophulariaceae Cycnium tubulosum Marshy ground


21


Melastomataceae Dissotis princeps Wild tibouchina Full sun, marshy areas

Asteraceae Ethulia conyzoides Blue weed Low-lying damp places

Cyperacae Fuirena pubescens Grassland wet or damp for most of the growing period, vleis and river margins

Iridaceae Gladiolus papilio Butterfly gladiolus Marshes and damp grassland

Gunneraceae Gunnera perpensa Wild Rhubarb Damp marshy areas

Liliaceae Kniphofia tysonii Red hot poker Wet grassland, full sun

Cyperacae Kyllinga alata Vlei or semi-vlei conditions in grassland

Cyperacae Kyllinga erecta Open swampy grassland and in vleis

Cyperacae Kyllinga pauciflora Damp or swampy grassland

Myricaceae Laportea peduncularis Stinging nettle Damp areas, stream edges, light shade

Onagraceae Ludwigia octovalvis Shrubby ludwigia Sun, damp swamp vegetation

Fabaceae Psoralea pinnata Margins of swamp forest, marshy grassland edges

Lamiaceae Pycnostachys reticulata Moist, swampy, grassy areas

Lamiaceae Pycnostachys urticifolia Moist, swampy, grassy areas

Cyperacae Pycreus macranthus Seasonal swamps, marshes, grassland floodplains

Cyperacae Schoenoplectus paludicola Temporary pools in grassland, along vlei and streamlet margins

Cyperacae Scleria woodii Damp vlei areas of grassland that are not waterlogged for long, partial shaded areas

Plant list 5: Temporary planting zone


Asteraceae Aspilia natalensis Wild creeping sunflower

Full sun in grassland

Asteraceae Crassocephalum picridifolium Full sun

Scrophulariaceae Cycnium racemosum Large pink ink plant Grassland, rocky places

Cyperacae Cyperus solitudus Open grassland in sun, usually along water courses but seldom in water, often forming local stands

Amaryllidaceae Cyrtanthus breviflorus Yellow fire lily Moist or dry grassland

Fabaceae Desmodium salicifolium Wetland edge, damp areas

Melastomataceae Dissotis canescens Wild tibouchina Full sun in marshy areas

Cyperacae Fuirena coerulescens

Temporary wet situations, usually seasonal vleis, pans or damp depressions in grassland, often where vegetation cover is sparse

Geraniaceae Geranium flanaganii Damp forest margins, marshy areas

Fabaceae Lotus discolor Coral plant Wetland edge, damp areas, moist grassland

Asteraceae Melanthera scandens Damp places, forest margins

Lythraceae Nesaea radicans Marsh Nesaea Sun, can take some shade, moist areas

Fabaceae Pseudarthria hookeri Velvet bean Seepage lines and forest edges

Ranunculaceae Ranunculus multifidus Common Buttercup Damp ground near stream, marshes

Lamiaceae Syncolostemon densiflorus Pink Plume Grassland, forest margins


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ANNEXURE B: Literature Review: Theoretical basis for wetland re-vegetation

B1. Role of vegetation in wetland ecology and importance for wetland rehabilitation

Vegetation plays an important role in natural wetland ecosystems. Wetland vegetation has

compositional and structural characteristics that provide specialized habitats for a range of wetland

dependent organisms and is well known for providing a range of wetland ecosystem goods and services

(Macfarlane et al., 2008). Wetland plants assist in binding the soil together and slow down the flow of

water, reducing the risk of erosion and promoting sediment deposition. Wetland plants are also a major

source of organic material in wetland soils and can affect the quality of surface and subsurface water

by providing soil organic matter required by microbes to assimilate nutrients and toxicants and plants

contribute through direct uptake of nutrients and toxicants (Russell, 2009).

Owing to the vital role of wetland vegetation in wetland ecosystem health and functioning, the re-

establishment of natural or semi-natural vegetation is widely recognized as an important component of

any wetland rehabilitation programme or plan. Generally, the broad aim of re-vegetation should be to

introduce desirable plants in order to develop a plant community that will eventually become naturally

self-sustaining over time (Brock & Casanova, 2000). The establishment of plants can be a rehabilitation

intervention in its own right or can be used to complement other interventions (Russell, 2009).

B2. Types of wetland vegetation

For many wetlands, not all parts of the wetland system are saturated for the same length of time and

generally there are three different “wetness zones”, which are distinguished according to the changing

frequency of saturation (DWAF, 2005). Vegetation within a wetland is commonly differentiated

according to the three main “zones of saturation” or “wetness zones” occurring within a wetland, namely:

• The permanent zone (permanently wet soils usually located at the centre of the wetland) where

water is present at or near the surface of the soil for the entire year;

• The seasonal zone (seasonally wet) where water is present for several months of the year (usually

linked to the rainy season); and

• The temporary zone (zone of temporary wetness) which is usually located on the periphery of

the wetland where the soil is saturated for only a short period of the year that is sufficient for the

formation of hydromorphic soils and the growth of wetland vegetation (usually for at least 2

weeks of the year).

Wetland plant communities generally undergo distinct changes in species composition as one proceeds

along the wetness gradient from the centre of a wetland towards adjacent terrestrial areas (represented

by a wetness continuum), as shown illustrated in Figure 2 and described in Table 1, below.

Table 1. Wetland plant hydric status (adapted from Macfarlane et al., 2008 and DWAF, 2005).

SYMBOL HYDRIC STATUS DESCRIPTION/OCCURRENCE

ow Obligate wetland species Almost always grow in wetlands (>90% occurrence)

Fw+ Facultative wetland species Usually grow in wetlands (67-99% occurrence) but

occasionally found in non-wetland areas

f Facultative species Equally likely to grow in wetlands (34-66% occurrence) and

non-wetland areas

Fd- Facultative dry-land species Usually grow in non-wetland areas but sometimes grow in

wetlands (1-34% occurrence)

d Dryland species Almost always grow in drylands


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Figure 2. Diagram representing the different zones of wetness found within a wetland (after DWAF, 2005).

Recognizing the variation in soil saturation within wetlands, the wetland re-vegetation programme will

need to consider the wetland zonation and the system should be sub-divided into a number of “planting

zones” that correspond to the periodicity of soil saturation (see Table 2, below).

Table 2. Wetland “planting zones” defined based on the soil wetness continuum (adapted from

Jacobson, 2006 and DWAF, 2005).

PLANTING

ZONE DESCRIPTION CHARACTERISITCS OF VEGETATION METHOD OF REVEGETATION

Permanent:

submerged

Constant and

permanently

standing deep

water habitat

This zone is comprised of aquatic plants

that are generally submerged entirely,

except for flowering parts. The plants

may be floating or rooted and will

generally not survive desiccation.

Plants are generally

established as tubers or

bulbs, rooted plants, plant

fragments, or as pre-

vegetated mats.

Permanent:

emergent

Constant and

permanently

standing shallow

water habitat

Emergent plants growing in permanently

saturated soils that are partially

submerged with leaves, stems and

flowering parts partially or entirely out of

the water. Plants are capable of growing

under saturated conditions and may

survive short periods of desiccation.

Emergent plants characterise this zone

and include reeds and bulrushes with only

those hydrophilic woody species with

morphological adaptations to prolonged

wetness (e.g. prop roots).

Emergent species are

generally installed as plants

or pre-vegetated mats

because they are planted in

the water. When planted in

the water, they need to

have a portion of their

leaves or stems above the

water surface or they will

drown. If seeded, the seed

should be placed either on

a mud flat or at the water’s

edge.

Semi-

Permanent

Soils are saturated

for most of the year

but can

occasionally dry out

during the

dry/winter season

The plants of this zone can tolerate

periodic flooding and desiccation

periods. These plant species usually grow

at the water’s edge where soils are

saturated but the ground surface is

frequently not inundated.

Many species can be

established as seed.

However, a number of

desirable species are only

available as plants or pre-

vegetated mats.

Seasonal

Soils are saturated

on a seasonal-basis

for several months of

the year, primarily

during the rainy

season

Within the zone of seasonal fluctuations in

soil saturation, wetland plants typically

comprise a mixture of hygrophilous

grassland and sedges.

Most species within this zone

are established as seed.


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PLANTING

ZONE DESCRIPTION CHARACTERISITCS OF VEGETATION METHOD OF REVEGETATION

Temporary

Peripheral areas

where the soil is in-

frequently saturated

for short periods of

time but is generally

quite dry

Many wetland plant species will tolerate

saturated and moist soil conditions for

extended periods of time. Mixture of non-

wetland species and hydrophilic plant

species restricted to wetland areas,

typically hygrophilous grassland type.

Most species within this zone

are established as seed.

B3. Common re-vegetation techniques & methods

• Natural recruitment vs active re-vegetation

In most wetland rehabilitation projects, once the natural hydrology of the system has been reset/re-

instated, wetland vegetation is likely to re-establish itself naturally through natural recruitment by

indigenous species and the planting of vegetation will generally not be necessary (Russell, 2009).

Wetlands can re-vegetate naturally through the germination of a ‘seed bank’ in the soils of the wetland

and/or as a result of seeds being carried into the wetland by birds and other animals, water or wind

(Clarkson & Peters, 2012). For these reasons, the primary approach to wetland management in many

cases is to allow wetlands to re-vegetate naturally, monitor their progress, implement corrective actions

where needed (e.g. weed control measures) and to implement a wetland development contingency

plan (FERC, 2011). This is considered the most cost-effective approach for large sites. Provided that

suitable conditions exist at a site a wetland may actually require little direct re-vegetation (Clarkson and

Peters, 2012). This includes the appropriate temperature range, enough water for sufficient time in the

right season, sufficient light, reduced competition from other plants, protection from plant eaters and a

suitable slope for plant establishment.

Active re-vegetation refers to the manual planting/seeding of vegetation within a wetland and is

considered important if there are risks involved in waiting for natural recruitment to occur or in situations

where re-vegetation may be useful or even necessary, depending upon the objectives of rehabilitation

or the particular conditions at a site (Russell, 2009). Re-vegetation of different wetlands is likely to require

planting mixes and planting strategies specific to a particular bioregion, or even at a local site level

(Jacobson, 2006). Planting the “wet zone” can be a complicated task that requires consideration of

water management levels, restrictions on use of herbicides, equipment limitations, site preparation and

a good understanding of the “wetness requirements” for various wetland plants (Wetland Care Australia,

2008).

• Methods of active re-vegetation

There are generally three main methods for establishing plants in a wetland: (1) seeding, (2) cuttings

(plant parts that can grow a new plant or clone), and (3) transplants (establishing whole plants). Some

projects may be done using seed only and others may be done using a combination of seeding and

planting. The selection of planting method(s) is largely dependent on the species that are selected for

replanting as well as the availability and nature of local plant material from donor sites. There are wetland

species that naturally only reproduce clonally and that can rarely be grown from seed whilst there are

other species that can only be reproduced from seed since they do not have the means for clonal

reproduction (Russell, 2009). Transplanting whole plants is often a very expensive and laborious exercise

but can be worth the effort if the transplants are from a nearby donor wetland site or if it involves large

species that give the wetland its characteristic vegetation structure (for example trees and shrubs). A

summary of the different methods is included below.

(1) Direct seeding:

Seed can be collected from existing growing wetland plants and scattered directly within the target wetland

as a form of re-vegetating wetland areas. Wetland plant seeds generally need three things to germinate: heat,

water, and light. The need for light means that wetland plant seeds need to be seeded on the surface and

they cannot be covered with soil (Hoag, 2005). Based on these difficulties, using direct seeding of herbaceous

plants as the primary means of re-vegetating a site will require more attention to planning and control of site

hydrology during the establishment period to be successful.

(2) Seed bank collection:

Many wetland species have seeds that live for several years (Brock & Casanova, 2000). A seed bank is the

store of dormant seeds from previous seasons within the sediment/soil of the wetland. The seeds from some

wetland plant species in the seed bank germinate every year; others wait until conditions are just right - which


25

may be once in several years (Brock & Casanova, 2000). In nature, germination from seed banks is patchy. A

small amount of seed bank can potentially re-vegetate an entire wetland as species tend to spread easily

through the systems (particularly along lines of water flow), but if soil is collected only from a few places, one

you may miss some of the more desirable species.

(3) Transplanting whole plants:

Some species of wetland plants may be difficult to obtain except through transplanting whilst others which are

rapid rhizome spreaders are easier to propagate by division than seedlings (Water and Rivers Commission,

2000). Wetland plants (or hydrophytes) tend to lack substantial underground rooting systems and are therefore

relocated quite readily (Hoag, 2005). Live plants are used to establish emergent aquatic vegetation in shallow

open water, deep marsh and shallow marsh zones because seed is difficult to establish in these “wet” zones.

Working with whole/growing plants does require a systematic approach, however (Russell, 2009). The timing of

transplanting is best done shortly before or at the beginning of the growing season and material for transplants

can originate from a commercial nursery or it can be taken from a donor site within the same wetland or an

adjacent/nearby wetland. If a donor wetland site is selected, there must be sufficient sites where it is safe to

remove plants without seriously damaging the donor wetland (Russell, 2009).

(4) Transplanting plant materials:

As with transplanting of whole plants, some species can be best propagated by taking cuttings from

established plant species at donor wetland sites. Substantial woody cuttings (or batons) or layers of live brush

wood from some tree species will take root if driven into the soil or if laid partially buried on the soil surface and

anchored into the soil below. Whole branches with off shoots anchored this way can protect the soil surface

from flowing water and help to trap debris and sediment (Russell, 2009).

• The role of nurseries

Where there is a very limited supply of planting material for use in active re-vegetation, it is recommended

that available material be multiplied by establishing a local plant nursery prior to wetland rehabilitation,

in order to build up plant stock for later planting (Russell, 2009). This also reduces the reliance on taking

plant material from donor wetlands. Nurseries have to be well planned and appropriately managed to

be successful. The young plants grown in the nursery must be protected from wind and harsh sunlight

that will dry them out, and from pests and diseases. It is important therefore that if a nursery is to be

developed, the specific expertise required must be secured.

B4. Selection of species for active re-vegetation

• Functional vs compositional aspects

In situations where active re-vegetation is desirable or even necessary, it is important to ensure that the

rehabilitation objective(s) of the wetland rehabilitation plan take into account plant species

requirements. The focus here will be either on the desired ‘functional aspects’ of species (such as water

filtering capacity or fast growth rate) or on the ‘compositional aspects’ of the wetland ecosystem that is

associated with the planted species (includes species diversity, origin of plants, etc.). The specific

rehabilitation objectives should therefore ultimately dictate whether functional or compositional aspects

are given priority, and how compromises should be sought. Examples of some typical rehabilitation

objectives and relevant species requirements are indicated in the table below:

REHABILITATION OBJECTIVES SPECIES REQUIREMENTS (after Russell, 2009)

Re-establishment of vegetation

in high energy wetlands

• Vigorous growth

• Strong roots

• Mat-forming

• High shoot density

Re-vegetation informed by

biodiversity concerns

• Resemble natural plant assemblages

• Avoid alien and invasive species (including indigenous species that are

known to be invasive)

• Rare species

Restoration of water filtering

capacity

• Plant species known to have a good capability to trap or remove

sediment, nutrients and/or toxic contaminants from water

Rehabilitation of eroded areas

• Vigorous growth

• Rhizomes or stolons

• Strong roots

• Mat-forming

• High shoot density

• Ability to trap sediment

Rehabilitation to meet demand

for local economic benefits

• Wetland plants are known and desired by local community

• Plants can be harvested sustainably


26

Whatever choice of species is made, it should always be borne in mind that species diversity is the key

to robustness (Russell, 2009). Wetlands are known to be complex and dynamic ecosystems, and while

the characteristics of a wetland system may change over time, the greater the species diversity, the

greater the chance of the system surviving the stresses of changing environmental factors (Russell, 2009).

Mono-specific species planting is therefore generally not recommended. It is also important to recognize

that it may take a wetland many years to develop self-sustaining vegetation and become a diverse

habitat and could require a number of iterations in the re-vegetation process.

• Habitat requirements for species

Wetlands typically present several kinds of habitat where plants can grow. Many aquatic plants are more

suited to one habitat type and some can have very specific habitat requirements which need to be

identified prior to plant selection (Brock & Casanova, 2000). Wetland plant habitat requirements may

include:

o Species that prefer the drier, temporarily wet edges of the wetland;

o Species that do well in soils that are seasonally or permanently inundated by shallow or deep

water;

o Plants that have a tolerance for exposure to wind, etc.; and

o Species that prefer full sun, partial shade or full shade.

• Ecological succession in wetlands

One of the most important aspects of a re-vegetation programme, especially with regards to biodiversity

conservation objectives, is whether the endpoint vegetation represents the natural or reference

vegetation state for the wetland system (Russell, 2009). Understanding ecological succession within

wetland is therefore an important component in re-vegetation, particularly when a site is re-vegetated

primarily for biodiversity restoration/enhancement purposes. Succession is the process whereby one

plant community gradually changes over time into another different community, with a contrasting

vegetation structure and/or species composition. It involves both arrivals and losses of species coupled

with changes in the relative abundance of different plants. This leads to a gradual change in species

composition and vegetation structure that is increasingly stable over time, until after many years a stable

“climax community” is established (Russell, 2009). The successional process is brought about by changes

in environmental conditions (e.g. weather, light, soil organic matter) and biotic interactions (such as

competition between species). Successional pathways are generally very difficult to predict, with

numerous alternative states in the climax community a possibility. For example, if common reed (P.

australis) arrives first in a wetland, favourable conditions may allow the species to expand throughout the

entire wetland and form a stable community, whereas alternatively, if certain sedge species

(Cyperacae) arrive before the reeds, they could result in an entirely different vegetation community,

where P. australis may not be capable of establishing itself widely within the wetland as it will be

competing with the established sedge community.

Implications of successional pathway for the re-vegetation programme/plan include the following:

o Wetland species that can cope with full sun, exposed and/or frosty conditions are typical of early

successional species or fast-growing/hardy “pioneer” plants that can be planted first. These

pioneer plants generally provide protection/shelter for later successional plants that are slower

growing, more shade tolerant and more sensitive to the elements.

o Enhancement planting of later successional wetland species may be required for rehabilitation

projects that do not have seed-source wetlands nearby (Clarkson and Peters, 2012). This situation

is especially the case in wetlands where one very successful species is present (such as Phragmites

australis or Typha capensis) that can colonize a site quickly, decreasing the chances of other

species establishing. Such species are known as “clonal species”, as a single individual (or

“clone”) may occupy large areas through self-replication.

o When different successional pathways are possible, re-vegetation measures will need to aim

towards a desired vegetation state that is in-line with the objectives/requirements as defined in

the wetland rehabilitation plan. Re-vegetation will give the species that are planted a decided

advantage over other opportunistic/invasive species that might compete with them.

o Often the assembly of natural communities is affected by chance (stochastic factors), which

plants arrive first and the order in which they arrive and establish.


27

• Competition & plant compatibility

Competition between plants can limit the success of a re-vegetation project. If a combination of species

is chosen for a particular re-vegetation programme, it is important to consider combinations of species

that are compatible with each other. Naturally, some species co-occur with each other, whereas other

species compete with each other, leading to a decrease in the performance of the plants and

eventually leading to the exclusion of one or more species (Russell, 2009). Plant species need to be

compatible not only with each other but also with existing adjacent native habitats. Clarkson & Peters

(2012) recognize that there are also species that can establish only when another ‘nurse’ plant is already

present to provide a microhabitat that is conducive for germination (e.g. some plants require the

shelter/shade of other larger plants to become successfully established). Ecological assembly rules deal

with possible species combinations and exclusions in natural ecosystems (i.e. which species can grow

together, and which cannot). According to Russell (2009), even though the research into ecological

assembly rules is still going on, it is possible to state a consider a few general rules that need to be taken

into account when selecting plants for re-vegetation. The most important is the rule of niche separation:

plants that grow together occupy a different niche within the same ecosystem which may be defined

either spatially or temporarily. This represents itself in the structure and functional type of plants, where

plants that grow well together should be dissimilar. For example: a plant may be a shallow rooter and the

other a deep rooter, or one may have large leaves overtopping other plants and the other small ones

that can still capture sufficient light in the understory.

• Undesirable plants

International literature generally indicates that while most species of alien plants are considered

undesirable in wetlands for a number of reasons (related to biodiversity conservation in particular), there

are also a number of indigenous species that have invasive potential and are also considered

undesirable as they can potentially conflict with the rehabilitation objectives for a site. These species

should not be initially selected when trying to establish a floristically diverse ecosystem. Examples in South

Africa include the indigenous obligate wetland species Typha capensis (common bulrush) and

Phragmites australis (common reed), which whilst locally common to South Africa, are considered

opportunistic invasive species that tend to capitalize on disturbed conditions at a site (e.g. altered water

volume/quality and other disturbances such as sedimentation). These opportunistic invader plants will

tend to crowd out other species, compete for nutrients and eventually dominate wetland habitats to

produce a low-diversity monoculture which is generally considered undesirable from a conservation

perspective.

• Planting for sustainable harvesting (after Russell, 2009)

When wetland re-vegetation needs to consider the socio-economic needs of a local community, it will

be important identify the local demand/needs/desires by keeping the community actively involved in

the rehabilitation process. Planting needs to bear in mind the potential to harvest the species

sustainably, which is dictated largely by the planting density. The ideal planting density is species-specific,

with most sedges and grasses having high densities in a wetland, whereas most herbs (including

medicinal plants) would be more sparsely dispersed over the wetland.

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