menanam pohon untuk memanen air hujan neraca lengas soemarno - psdl ppsub 2013

MENANAM POHON UNTUK

MEMANEN AIR HUJAN

NERACA LENGAS

Soemarno - psdl ppsub 2013

Vegetation and land-use effects on soil properties and water infiltration of Andisols in Tenerife (Canary Islands, Spain)

J. Neris, C. Jiménez , J. Fuentes, G. Morillas, M. Tejedor.CATENA. Volume 98, November 2012, Pages 55–62

Diunduh dari sumber: http://www.sciencedirect.com/science/article/pii/S0341816212001270 …..29/10/2012

Andisols are soils with high structural development and aggregate stability, characteristics that play a major role in their

high infiltration rate. They are, however, vulnerable to environmental changes, particularly those associated with land

use modifications. The present work aims to ascertain the influence of modifications

to land use as well as vegetation cover on the steady-state infiltration rate and associated properties of Andisols on the volcanic island of Tenerife (Canary Islands, Spain). Thirty two sites were selected in three categories of land use/vegetation

cover (green forest, pine forest and cropped areas). The infiltration rate was studied using a double ring infiltrometer.

Other soil properties which influence infiltration – organic matter content, texture, structure, bulk density, water retention capacity

and water repellency – were also studied. Infiltration is extremely rapid under green forest (796 mmh− 1) but falls considerably under pine forest (188 mmh− 1) and in formerly cropped soils (67 mmh− 1). The statistical analysis shows that the main soil properties affected by a change in land use/vegetation and which determine infiltration are soil aggregation, structural

stability and, to a lesser extent, organic matter and bulk density. Compared to the green forest sites, a notable reduction in soil

aggregation, structural stability and organic matter, and an increase in bulk density, are observed in the formerly cropped

soils. Although less pronounced, the same tendency is seen also in the pine forest sites when compared to their green forest

counterparts. The results confirm the vulnerability of Andisols' soil properties and infiltration to land use modification, while also highlighting

the influence of the type of forest cover present.




Water repellence severity of different vegetation and land use types.




Influence of soil type, vegetation and land uses on steady infiltration rate (SIR) and classification according to

Landon (1984), modified (Box plot: thick bar = median; upper and lower limits of the box = 75 and 25 percentiles,

respectively).

http://www.sciencedirect.com/science/article/pii/S0341816212001270




Hasil analisis PCA untuk berbagai tipe vegetasi dan landuse.




Hubungan antara infiltrasi dan sifat-sifat tanah (organic carbon, bulk density, water retention, soil aggregation dan

stabilitas agregat tanah).

Effects of vegetation-related soil heterogeneity on Runoff, infiltration, and redistribution in semi-arid Shrubland and

grassland landscapes David Ralph Bedford

B.S., Colorado state university, 1996

Diunduh dari sumber: http://gradworks.umi.com/3337180.pdf …..29/10/2012

Model Konseptual proses redistribusi air hujan dalam hubungannya dengan vegetasi dan sifat-sifat

tanah





Hubungan antara relief microtopographic dan runoff untuk berbagai karakter hujan.

Shaded area denotes the roughness of the “Lower1” plot





Infiltration variability (left-hand panel) for different patterns (right-hand panels) of Ksat (dashed line) and Zm (solid line). Ksat varies by 2x. Error bars denote

the standard deviation; values greater than unity suggest redistribution. Topography profiles have a

10x exaggeration

The effect of vegetation on infiltration in shallow soils underlain by fissured bedrock

S.A. Stothoff, D. Or, D.P. Groeneveld, S.B. JonesJournal of Hydrology 218 (1999) 169-190.

Diunduh dari sumber: http://www.hydrobio.org/publications/DG_99_Veg_Effect_YM_Infiltration_JH.pdf…..

29/10/2012

Ongoing investigations of infiltration processes have identified the relatively horizontal caprock environment above portions of

the repository as a potentially large source of infiltrating waters, due to shallow, permeable soils above a moderately

welded tuff with large soil-filled fissures.

The combination of shallow soils and fissured bedrock allows rapid penetration of wetting pulses to below the rooting zone.

Plant uptake can strongly reduce net infiltration in arid environments with high water storage capacity, and, despite the low water storage capacity, there is a relatively high vegetation

density in this environment.

The apparent discrepancy between high vegetation density and low water storage motivates the study of plant-hydrologic

interactions in this semiarid environment. Field observations were coupled with plant- and landscape-scale models to provide

insight into plant-hydrologic interactions.

Several lines of evidence, including: (i) linear plant growth features observed on aerial photographs; (ii) comparisons of plant cover within the fissured environment and comparable environments lacking fissures; and (iii) direct excavations, all

suggest that the widely spaced soil- filled fissures are conducive to plant growth even when fissures are buried at soil depths

exceeding 30 cm.




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Results from a mechanistic simulation model for root growth into fissures suggest that the additional (sheltered) plant-available soil water within fissures provides a competitive advantage for plant establishment. Therefore, plants that

germinate above a fissure are more likely to survive, in turn developing linear features above fissures. Having established that plants preferentially root within soil-filled fissures in the caprock environment, a set of simulations were performed to examine the hydrologic consequence of plant roots within

fissures at the landscape-scale. The response to three rainfall amounts was simulated. For the

largest storm, fluxes at the fissure bottom peaked at 1-4 weeks after the storm when plant uptake was not active, but were

eliminated when fissures had active vegetation. When plants were active within a fissure, uptake eliminated

net infiltration in the fissure regardless of the size of the storm.

Two plant-related mechanisms reduced total flux through the plant-filled fissures: (i) transpiration during fissure flow, and

(ii) wetting-pulse retardation due to drier fissures prior to rain. The first mechanism appears to be dominant in these

simulations. Results suggest that transpiration may strongly limit net

infiltration (i.e. total deep percolation flux escaping the plant root zone); significant infiltration can occur, however, when

plants are dormant, so that most infiltration would be expected to occur during winter.




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Hydrologic interactions have been less examined in shallow soils underlain by fractured bedrock. Several

studies are discussed by Sternberg et al. (1996).

They note that in many mountainous sites with shallow soils, soil water storage is inadequate to support existing vegetation and several studies

have found that roots of woody plants may penetrate many meters into bedrock along fracture planes

and joints.

In a field study with highly weathered bedrock, Sternberg et al. (1996) found that the bedrock

supplied nearly ten times as much water than did the soil, suggesting that weathered bedrock may form

an important ecosystem component.

1. Sternberg, P.D., Anderson, M.A., Graham, R.C., Beyers, J.L., Rice. K.R., 1996. Root distribution and seasonal water status in weathered granitic bedrock under chapparal. Geoderma 72, 89-98.




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Ciri-ciri hidrologis dari caprock.

The mildly sloping caprock surface is overlain by loamy sand soil of variable thickness, from exposed caprock to depths of about 0.5 m. Soil texture varies with depth from loamy sand to loam, typically features a light desert pavement at the surface, and exhibits occasional embedded rock shards and fragments

at all depths. The fine-content composition (<2 mm) is remarkably spatially

uniform.




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Model untuk investigasi pertumbuhan akar : (a) fissured bedrock system, and (b) solid bedrock (no

fissure exists).




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Simulated root systems after 90 d of growth: (a) side view of the entire root system for the fissure simulation: (b)-(d) expanded views of the top of the root system for the fissure simulation. from the top, parallel to the tissure, and perpendicular to the

fissure, respectively: (e)-(g) the entire root system for the solid-bedrock (no fissure) simulation from the same directions as in

(b)-(d). Shaded areas represent bedrock while white areas denote soil.




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Water flux in each of the five fissures following a 100 mm precipitation event: (a) and (b) top (T) and bottom (B) of soil-

filled portion without plant uptake; (c) and (d) top (T) and bottom (B) of soil-filled portion with plant uptake.

Gross precipitation, throughfall, and stemflow were measured in a representative matorral subinerme study plot within a small

montane basin of the Sierra Madre Oriental throughout three wet season periods.

Data analysis suggests that of the 394.8 mm of cumulative gross precipitation generated by 25 sampled events, throughfall,

stemflow, and canopy interception loss fluxes were 329.0±7.7 mm (83.3±1.9%), 33.5±7.6 mm (8.5±1.9%), and 32.3±10.8 mm

(8.2±2.7%), respectively. Stemflow from four woody plant stems was found to be moderately correlated (r=0.54) with the product of gross

precipitation multiplied by stem basal area, while the season-long Herwitz (Earth Surf. Process. Landforms 11 (1986) 401) funneling

ratios for these stems averaged 21.1.

The relatively large concentrations of water delivered to the bases of these plants suggest that stemflow generation may be a means

of surviving drought conditions. The importance of and possible factors influencing during-event evaporation from the saturated matorral subinerme canopy, as

well as recommendations for future canopy water flux studies in this plant community, are discussed.

Throughfall, stemflow, and canopy interception loss fluxes in a semi-arid Sierra Madre Oriental matorral community

D.E Carlyle-MosesJournal of Arid Environments. Volume 58, Issue 2, July 2004, Pages 181–202

Diunduh dari sumber: http://www.sciencedirect.com/science/article/pii/S0140196303001253…..30/10/2012

Huungan antara hujan bruto (mm) dengan kedalaman throughfall (mm) pada kondisi tajuki musim basah.




Throughfall sebagai persentase dari hujan bruto (mm) dalam komunitas “matorral subinerme” di bawah kondisi tajuk

musim basah.




Volume aliran-batang Stemflow (l) sebagai fungsi dari hujan bruto (mm) × luas basal batang di lokasi petak-

uji “matorral subinerme”.




Intersepsi tajuk (mm) merupakan fungsi dari hujan bruto (mm) dalam komunitas “subinerme community” pada

kondisi tajuk musim basah.




Intersepsi tajuk (%) sebagai fungsi dari hujan bruto (mm) dalam komunitas “matorral subinerme” pada kondisi tajuk

musim basah.




. Alteration of the hydrologic cycle due to forest clearing and its consequences for rainforest succession

M. Francisca Díaz, Seth Bigelow, , Juan J. Armesto.Forest Ecology and Management. Volume 244, Issues 1–3, 15 June 2007,

Pages 32–40.


We hypothesized that the arrested conversion back to forests may reflect a nearly permanent condition associated with a rise in the

water table. To evaluate this possibility we acquired data from a 60-year old evergreen forest and an area in shrub cover to

parameterize two hydrologic models; one that accounts for hourly interception losses and predicts net precipitation (Gash model), the other that calculates hourly transpiration from both overstory and understory components as well as evaporation from the soil (a

modified Penman–Monteith model). In addition, standpipes were installed to record water table levels over 18 months. The fraction of

a total annual precipitation ( 2100 mm) transpired by shrub and ∼forest cover differed (8% versus 22%) roughly in proportion to

differences in the leaf area index (2.2 versus 5.0). Although whole canopy (stomatal) conductances were similar, the aerodynamic

conductance was more than three-fold higher for forests compared with shrub cover ( 12 mol m∼ −2 s−1 versus 3 mol m−2 s−1).

The frequent wetting of tree canopies, combined with an average wind speed of 0.74 m s−1, resulted in 30% interception losses from ∼

forests compared with 1% of annual precipitation lost through this pathway from shrub cover. As a result of these differences, only

about half of the precipitation enters the ground under forest cover compared to 90% under shrub cover. This difference in canopy interception losses accounts for a rise in the water table from an

average of 45–10 cm. The high water table prevents normal tree regeneration. This

condition is stable unless an effort is made to provide an elevated substrate for tree seedlings to become established.



Pages 32–40.


Canopy (a) and aerodynamic (b) conductance from forest (closed circles) and successional shrubland (open

circles) in Chiloé Islands. Measurements were made during one clear day on April 2002, from 9 a.m. to 5 p.m.



Pages 32–40.


Water balance model for a young (60-year old) broad-leaved, evergreen forest in northern Chiloé Island, based on

parameters estimated in this work for the period 2002–2003. Percentages are relative to total precipitation (P). I: interception; T: transpiration; E: evaporation; ET:

evapotranspiration; Sf: stemflow; Th: throughfall; Pnet: net precipitation.



Pages 32–40.


Water balance model for secondary shrubland, established after clearcutting of forest in northern Chiloé Island. This

picture shows differences in model parameters in response to canopy removal. Model was based on parameters estimated in this work for the period 2002–2003. Percentages are relative to

total precipitation (P). I: interception; T: transpiration; E: evaporation; ET: evapotranspiration; Pnet: net precipitation.



Pages 32–40.


Groundwater depth in a secondary shrubland and adjacent broad-leaved forest stand in northern Chiloé Island for the

period 2002–2003. Circles are mean monthly values of water table depth ± 1S.E. in secondary shrubland (open) and forest (closed). Bars are monthly precipitation values for the same

period in mm. Horizontal line at 60 cm depth indicates maximum depth of detection and the approximate position of

the hardpan layer.

Diunduh dari sumber: http://learning.covcollege.ac.uk/content/Jorum/cat3_cp/catch106.htm …..31/10/2012

Initially all the precipitation is intercepted by the foliage and the area underneath remains dry. If the precipitation continues, eventually the canopy will become saturated and water will drip through the foliage to the ground as

throughfall or down the trunk (via the branches) as stemflow. These processes occur on a smaller scale with

smaller plants.

Diunduh dari sumber: http://learning.covcollege.ac.uk/content/Jorum/cat3_cp/catch085.htm

…..31/10/2012

SIKLUS HIDROLOGI

SIKLUS HIDROLOGI


…..31/10/2012

Soil water storage is the quantity of water held in the soil at any given point in time. It is usually applied to a soil layer of a given depth (often

between 30cm and 100cm). Water is held in the soil by the attraction of water

molecules to each other and to soil particles. Water is held in one of three ways.

VEGETATION AND CANOPY STORAGE

Diunduh dari sumber: http://learning.covcollege.ac.uk/content/Jorum/cat3_cp/catch088.htm …..

31/10/2012

After the precipitation has finished the vegetation and soil surfaces are wet because of interception.

Under the right conditions evaporation , which took place even when rain was falling, will continue. Transpiration , which takes place through the

stomata of plants, will also continue. Water is stored in the canopy ( interception ) and

within the plant tissues (vegetation storage). Vegetation storage ( VS ) is the volume of water

stored in the canopy and the plant tissues.

Groundwater storage

Diunduh dari sumber: http://learning.covcollege.ac.uk/content/Jorum/cat3_cp/catch120.htm …..31/10/2012

Groundwater can be present with

the soil, superficial

deposits and solid rock.

Kalau tanah kering, biasanya laju infiltrasinya tinggi. As more water is added to the soil over time it becomes wetter and the infiltration rate declines. This is usually shown as a graph of infiltration rate

(mm hr -1) plotted against time.

INTERSEPSI


…..29/10/2012

Precipitation (rain in this example) begins. Some of the rain falls on the vegetation and is

caught by the leaves and branches. This process is called interception and is a storage component of

the hydrological system. The water is stored on the vegetation foliage.

Water can also be intercepted by urban surfaces e.g. roofs, pavements and roads as well as by

vegetation.

TRANSPIRASITranspiration is the loss of water from the vascular system of

plants to the atmosphere. This occurs via stomata (small openings in leaves).

This is a biologically controlled process and forms an output from the hydrological system.

The plant draws water from the soil into roots, up through the plant and transpires it from stomata on leaves. Stomata respond

to daylight and therefore transpiration occurs during the day.

Diunduh dari sumber: http://learning.covcollege.ac.uk/content/Jorum/cat3_cp/catch093.htm…..

31/10/2012

Transpiration depends on the factors affecting evaporation and also

on:

1. time of day 2. type and amount of

vegetation 3. length of growing

season 4. time of year

(especially for deciduous plants)

Tree rings and streamflow

http://treeflow.info/lees/treering.html

The soil moisture around an individual tree reflects the overall water balance of a river basin

(precipitation minus evapotranspiration) and thus the amount of streamflow produced by the

basin.

. Soil water balance

www.fao.org/docrep/x0490e/x0490e04.htm

Evapotranspiration can also be determined by measuring the various components of the soil water balance. The

method consists of assessing the incoming and outgoing water flux into the crop root zone over some time period (Figure 6). Irrigation (I) and rainfall (P) add water to the

root zone. Part of I and P might be lost by surface runoff (RO) and by deep percolation (DP) that will eventually

recharge the water table. Water might also be transported upward by capillary rise (CR) from a shallow water table

towards the root zone or even transferred horizontally by subsurface flow in (SFin) or out of (SFout) the root zone. In many situations, however, except under conditions with

large slopes, SFin and SFout are minor and can be ignored. Soil evaporation and crop transpiration deplete water from

the root zone. If all fluxes other than evapotranspiration (ET) can be assessed, the evapotranspiration can be

deduced from the change in soil water content (D SW) over the time period:

ET = I + P - RO - DP + CR ± D SF ± D SW ….. (2)

Some fluxes such as subsurface flow, deep percolation and capillary rise from a water table are difficult to assess

and short time periods cannot be considered. The soil water balance method can usually only give ET estimates over long time periods of the order of week-long or ten-

day periods.

. Soil water balance

www.fao.org/docrep/x0490e/x0490e04.htm

Soil water balance

http://www.fao.org/docrep/x0490e/x0490e0e.htm

The estimation of Ks requires a daily water balance computation for the root zone.

Schematically the root zone can be presented by means of a container in which the water content may fluctuate. To

express the water content as root zone depletion is useful. It makes the adding and subtracting of losses and gains

straightforward as the various parameters of the soil water budget are usually expressed in terms of water depth.

Rainfall, irrigation and capillary rise of groundwater towards the root zone add water to the root zone and

decrease the root zone depletion. Soil evaporation, crop transpiration and percolation losses remove water from

the root zone and increase the depletion.

SIKLUS HIDROLOGI

http://cnrit.tamu.edu/rlem/textbook/Chapter6.htm

Underground and Overland Flow. Water originating from a source other than onsite precipitation may be an important

component of an ecosystem's water balance. Water flowing in surface channels or in shallow groundwater reserves may be accessed by deep-rooted trees and

shrubs. When roots reach a water table the plants are referred to as phreatophytes. Phreatophytic communities (e.g., oases and riparian communities) are an important

component of and ecosystems.

Significance of tree roots for preferential infiltration in stagnic soils

B. Lange1,2, P. Lüescher1, and P. F. Germann

Hydrol. Earth Syst. Sci., 13, 1809-1821, 2009

http://www.hydrol-earth-syst-sci.net/13/1809/2009/hess-13-1809-2009.html

It is generally recognized that roots have an effect on infiltration.

In this study we analysed the relation between root length distributions from Norway spruce (Picea abies (L.) Karst),

silver fir (Abies alba Miller), European beech (Fagus sylvatica L.) and preferential infiltration in stagnic soils in

the northern Pre-Alps in Switzerland.

We conducted irrigation experiments (1 m2) and recorded water content variations with time domain reflectometry

(TDR).

A rivulet approach was applied to characterise preferential infiltration.

Roots were sampled down to a depth of 0.5 to 1 m at the same position where the TDR-probes had been inserted

and digitally measured.


B. Lange1,2, P. Lüescher1, and P. F. Germann

Hydrol. Earth Syst. Sci., 13, 1809-1821, 2009

http://www.hydrol-earth-syst-sci.net/13/1809/2009/hess-13-1809-2009.html

The basic properties of preferential infiltration, film thickness of mobile water and the contact length between soil and mobile water in the horizontal plane are closely

related to root densities.

An increase in root density resulted in an increase in contact length, but a decrease in film thickness.

We modelled water content waves based on root densities and identified a range of root densities that lead to a

maximum volume flux density and infiltration capacity.

These findings provide convincing evidence that tree roots in stagnic soils represent the pore system that

carries preferential infiltration. Thus, the presence of roots should improve infiltration.

Heterogeneous Soil Water Dynamics around a Tree Growing on a Steep Hillslope

Wei-Li Liang, Ken'ichirou Kosugi and Takahisa Mizuyama

Vadose Zone Journal 2007. Vol. 6 No. 4, p. 879-889

https://www.soils.org/publications/vzj/abstracts/6/4/879

The results showed that the soil water content increased rapidly and greatly in the region

downslope from the tree stem, especially at points close to the tree stem.

At these points, maximal soil water storage was >100 to 200% of the cumulative open-area

rainfall, and occurrences of bypass flow were recognized.

Moreover, the pore water pressure at the soil–bedrock interface increased more rapidly and to a greater degree in the region downslope from

the tree stem than in the upslope region.

Heterogeneous Soil Water Dynamics around a Tree Growing on a Steep Hillslope

Wei-Li Liang, Ken'ichirou Kosugi and Takahisa Mizuyama

Vadose Zone Journal 2007. Vol. 6 No. 4, p. 879-889

https://www.soils.org/publications/vzj/abstracts/6/4/879

For a heavy storm event, the cumulative stemflow per infiltration area along the

downslope sides of the tree trunk was 18.9 times the cumulative open-area rainfall.

Locally concentrated rainwater input attributable to the stemflow on the downslope side of the

tree trunk probably caused the large and rapid increases in water content and pore water

pressure in the downslope region, resulting in the development of an asymmetric saturated

zone around the tree.

Ilstedt, U., Malmer, A., Verbeeten, E., Murdiyarso, D. 2007. The effect of afforestation on water infiltration in the

tropics: systematic review and meta-analysis . Forest Ecology and Management 251 :45-51. ISSN: 0378-1127.

http://cgspace.cgiar.org/handle/10568/19743

Soil water infiltration influences groundwater recharge and potential top soil loss by erosion, as well as the

partitioning of runoff into slow flow and quick flow.

The aim of the work presented here was to critically review studies of the effects of afforestation on infiltrability in the

tropics, using a systematic review approach to select peer-reviewed articles published in English and French.

We then applied meta-analysis to test the hypothesis that afforestation or the use of trees in agriculture increases

infiltration capacity.

After assessing titles and abstracts, on the basis of specified selection and quality criteria, four references

remained, comprising 14 comparative experiments.

Ilstedt, U., Malmer, A., Verbeeten, E., Murdiyarso, D. 2007. The effect of afforestation on water infiltration in the

tropics: systematic review and meta-analysis . Forest Ecology and Management 251 :45-51. ISSN: 0378-1127.

http://cgspace.cgiar.org/handle/10568/19743

The overall result of the meta-analysis was that infiltration capacity increased on average approximately three-fold after afforestation or planting trees in agricultural fields

(95% confidence interval: 2.4–4.7).

For the meta-analysis, the most common problems resulting in exclusion of otherwise relevant experiments

were issues with the experimental design, and the absence of statistics (variances and replicates).

Even considering the studies that were excluded in the meta analysis (a total of six), the low number of studies

examining the effects of afforestation is a severe problem with respect to modelling and examining the underlying

processes associated with the full range of different edaphic situations, different species and different

methods of establishment.


B. Lange, P. Luescher, and P. F. GermannHydrol. Earth Syst. Sci. Discuss., 5, 2373–2407, 2008

www.hydrol-earth-syst-sci-discuss.net/5/2373/.../hessd-5-2373-2008.pdf

It is generally believed that roots have an e ect on ffinfiltration. In this study we analysed the influence of tree

roots from Norway spruce (Picea abies (L.) Karst), silver fir (Abies alba Miller) and European beech (Fagus sylvatica

L.) on preferential infiltration in stagnic soils in the northern pre-Alps in Switzerland.

We conducted irrigation experiments (1m2) and recorded water content variations with time domain reflectrometry

(TDR). A rivulet approach was applied to characterise preferential infiltration. Roots were sampled down to a depth of 0.5 to 1m at the same position where the TDR-

probes had been inserted and digitally measured.

The basic properties of preferential infiltration, film thickness of mobile water and the contact length between soil and mobile water in the horizontal plane are closely related to fine root densities. An increase in root density

resulted in an increase in contact length, but a decrease in film thickness.

We modelled water content waves based on fine root densities and identified a range of root densities that lead

to a maximum volume flux density and infiltration capacity.

The effect of afforestation on water infiltration in the tropics:A systematic review and meta-analysis

Ulrik Ilstedt, Anders Malmer, Elke Verbeeten, Daniel Murdiyarso

www.aseanbiodiversity.info/abstract/51009844.pdf

Soil water infiltration influences groundwater recharge and potential top soil loss by erosion, as well as the partitioning of

runoff into slow flow and quick flow.

The aim of thework presented herewas to critically review studies of the effects of afforestation on infiltrability in the tropics, using

a systematic review approach to select peer-reviewed articles published in English and French.

We then applied meta-analysis to test the hypothesis that afforestation or the use of trees in agriculture increases

infiltration capacity.

After assessing titles and abstracts, on the basis of specified selection and quality criteria, four references remained,

comprising 14 comparative experiments.

The effect of afforestation on water infiltration in the tropics:A systematic review and meta-analysis

Ulrik Ilstedt, Anders Malmer, Elke Verbeeten, Daniel Murdiyarso

www.aseanbiodiversity.info/abstract/51009844.pdf

The overall result of the meta-analysis was that infiltration capacity increased on average approximately three-fold after

afforestation or planting trees in agricultural fields (95% confidence interval: 2.4–4.7).

For the meta-analysis, the most common problems resulting in exclusion of otherwise relevant experiments were issues with the experimental design, and the absence of statistics (variances and

replicates).

Even considering the studies that were excluded in themeta analysis (a total of six), the low number of studies examining the

effects of afforestation is a severe problem with respect to modelling and examining the underlying processes associated

with the full range of different edaphic situations, different species and different methods of establishment.

Austral Ecology (2005) 30, 336–347

Ecosystem wicks: Woodland trees enhance water infiltration in a fragmented agricultural landscape in

eastern AustraliaDAVID J. ELDRIDGE, AND DAVID FREUDENBERGER.

We examined infiltration through coarse- and fine-textured soils within four landscape strata, the zones below Eucalyptus

melliodora and Callitris glaucophylla canopies, the intertree zone dominated by perennial grasses and a landscape

homogenized by cultivation and dominated by annual crops.

We measured sorptivity, the early phase of water flow, and steady-state infiltration with disc permeameters at two supply

potentials.

These different potentials enabled us to separate infiltration into (i) flow through large (biopores) and small pores and (ii) flow through small pores only where biopores are prevented from

conducting water.

Austral Ecology (2005) 30, 336–347

Ecosystem wicks: Woodland trees enhance water infiltration in a fragmented agricultural landscape in

eastern AustraliaDAVID J. ELDRIDGE, AND DAVID FREUDENBERGER.

On the fine-textured soils, both sorptivity and steady-state infiltration were significantly greater (approximately fivefold)

under the timbered strata compared with the grassy slopes or cultivation. Differences were attributable to the greater

proportion of macropores below the tree canopies compared with the nontimbered strata.

The lack of a significant difference on the coarse-textured soils, despite their macropore status, was attributed to differences in surface litter and plant cover, which would maintain continuous macropores at the surface and thus conduct large amounts of

water.

The tendency of slopes covered by cryptogamic crusts and grasses to shed run-off and for the trees to absorb substantial quantities of water reinforced the important ecological service provided by trees, which moderates large run-off events and

captures small amounts of water leaking from the grassy patches.

Stormwater Quantity and Rate Control Benefits of Trees in Uncompacted Soil

http://www.deeproot.com/blog/blog-entries/stormwater-quantity-and-rate-control-benefits-of-trees-in-uncompacted-soil

A big part of this blog is devoted to the discussion of trees, soil, and stormwater in the urban context.

Today I want to walk through the three processes that allow trees in uncompacted soil to provide stormwater quantity and rate

control benefits: Soil storage; Interception; and Evapotranspiration

http://www.deeproot.com/blog/blog-entries/stormwater-quantity-and-rate-control-benefits-of-trees-in-uncompacted-soil/stormwater-rootball-small-3



Soil Storage

Soil stores rain water during and after a storm, making it available for plant growth. Stormwater runoff from nearby

impervious surfaces can be directed into soil under suspended pavement using a number of different techniques, such as, for

example, through pervious pavement installed over the cells, or via a perforated pipe off a trench drain or manhole.

A typical tree in suspended pavement can hold the 2.54 cm (1 inch) storm event from impervious surface area significantly

greater than just the area under the tree canopy.

For example, one tree with 28.3 m3 (1000 cubic feet) of uncompacted soil with 20% soil water storage capacity (a

conservative estimate since some bioretention soils can hold up to 40% water) can hold the 2.54 cm (one inch) 24 hour storm event from 223 m2 (2,400 square feet) of impervious surface.

Stormwater calculations for trees for bioretention typically account only for soil storage, not for interception and

evapotranspiration.



Interception

Interception is the amount of rainfall temporarily held on tree leaves and stem surfaces. This rain then drips from leaf surfaces

and flows down the stem surface to the ground or evaporates.Interception is not typically included in stormwater calculations

but can nonetheless provide additional stormwater benefits beyond stormwater storage in the soil.

The volume of rain intercepted depends on the duration and rate of the rainfall event, tree architecture (e.g. leaf and stem surface

area, roughness, visual density of the crown, tree size, and foliation period), and other meteorological factors.

Since larger trees have more leaves to intercept rain, they intercept significantly more rain than small trees, with interception increasing at a faster rate than tree age.

For example, a model of a hackberry tree in the Midwest estimates that interception will increase as follows with tree age:

1. a 5 year old hackberry intercepts 0.5 m3 (133 GAL) rainfall per year2. a 20 year old hackberry intercepts 5.3 m3 (1,394 GAL) rainfall per year3. a 40 year old hackberry intercepts 20.4 m3 (5,387 GAL) rainfall per year



Stormwater interception by hackberry trees versus age of tree (adapted from McPherson et al, 2006)

http://www.deeproot.com/blog/blog-entries/stormwater-quantity-and-rate-control-benefits-of-trees-in-uncompacted-soil/hackberries-2



Evapotranspiration

Evapotranspiration (ET) is the sum of water evaporated from soil and plant surfaces and the water lost as a result of transpiration,

a process in which trees absorb water through their roots and transfer it up to the leaves, where it evaporates into the

environment through leaf pore transpiration. Evapotranspiration continues to reduce stormwater volume stored in the soil long

after a rainfall event ends.

Transpiration rate is influenced by factors such as tree species, size, soil moisture, increasing sunlight (duration and intensity), air temperature, wind speed and decreasing relative humidity.

Potential evapotranspiration (PET) exceeds precipitation during the growing season in much of the US. Even tree transpiration

can exceed precipitation where it is sustained by irrigation (Grimmond and Oke 1999).

A study by Sinclair et al (2005) showed that:

“Transpiration was unaffected by soil drying until the initial estimated transpirable soil water fraction had decreased to

between 0.23 and 0.32 of that at field capacity. Beyond this point, transpiration rate declined linearly with available soil water

fraction until reaching one fifth the rate observed in well watered plants. With further soil drying, the relative transpiration rates remained between 10 and 20% of that observed in well watered

plants.”



Transpiration uses heat from the air to change the water in the vegetation into water vapor, so in addition to providing stormwater benefits, transpiration also decreases ambient air temperature and reduces the urban heat island effect.

Trees in a parking lot in Davis, CA, for example, reduced asphalt temperatures by as much as 20° C (36° F), and car

interior temperatures by over 26° C (47° F) (Scott et al 1999).

It is the responsibility of designers to create conditions that are favorable to trees and the sustainable processes

that they enable to occur in the built environment.

Hopefully this outline of their incredible benefits will help professionals to make sure sites that the sites they design

continue to support these ecological principles.

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