Methods of vegetation sampling:http://www.blm.gov/nstc/library/pdf/samplveg.pdfhttp://www.blm.gov/nstc/library/pdf/MeasAndMon.pdf

Range cover types of the US:ftp://ftp-fc.sc.egov.usda.gov/GLTI/technical/publications/

cover.pdf

Ecological site inventory technical reference:http://www.blm.gov/nstc/library/1734-7direct.html

Indicators of rangeland health:http://www.blm.gov/nstc/library/pdf/1734-6.pdf

Seminars

• EECB seminar Thurs 4:00 PM OSN 120. Dr. Larry Stevens, Grand Canyon Wildlands Council. “Biogeography of the Grand Canyon, and Colorado River Management”.

Reading

• Textbook Chapter 12 and 13• Sparrow, A., M. Friedel, and D. Tongway.

2003. Degradation and recovery processes in arid grazing lands of central Australia part 3: implications at landscape scale. Journal of Arid environments 55: 349-360.

Outline1. Case study: identifying communities and

relating to environmental conditions2. Student case studies3. Productivity – plants and ecosystems 4. GPP, NPP, and Efficiency5. Global and environmental patterns of

NPP6. Production in forest VS rangeland7. Factors influencing productivity – fire,

herbivory, nutrient pulses, etc.8. Climate change, CO2 accumulation, and

carbon sequestration

Species interactions and restoration

• Rangeland in Kenya: high productivity, high rainfall (600mm/yr).

• Massai traditionally nomadic pastoralists but now becoming sedentary.

• Can no longer move when pasture bad; must use land stewardship.

• Land highly overgrazed, and desertification widespread (80%?).

Fertile islands?• Aloe secundiflora shrubs have

vegetation around them even in eroded areas

• Aloe is unpalatable as an adult• Positive effect appears to extend

beyond range of aloe canopy• Potential facilitation effect?

Theory of facilitation• Presence of one plant species enables

others to persist• One species ameliorates environment;

facilitation important in harsh conditions.

• Positive environmental effects outweigh possible negative competition effects

• This may switch with plant life stage (e.g. facilitate as seedling, compete as adult)

Additional Value of Aloe?• Aloe is a medicinal plant; “poached”

from the wild for sap• Massai ranchers need cash rather

than cattle• If planting aloe can facilitate range

recovery, is this a “win-win” situation for Massai?

What ecological interactions/processes need to be considered?

Aloe as facilitator1. Quantification of spatial pattern

(circumstantial evidence)2. Basic experimentation on species

interactions (does aloe facilitate other species?)

3. Establishment of dryland agriculture and range restoration programWork by Elizabeth King, UC Davis

Aloe as facilitator1. Quantification of spatial pattern

(circumstantial evidence)– Spatial pattern: aloe plants retain soil,

have higher soil fertility, more litter, greater soil seed bank, higher cover and diversity of surrounding vegetation. Soil retention

Aloe as facilitator1. Quantification of spatial pattern

(circumstantial evidence)2. Basic experimentation on species

interactions:• Plant Aloe, compare to thorns (grazing

protection) and control (soil disturbance)• Plant Cenchrus cilliaris, observe growth.• Cenchrus growth substantially enhanced

by Aloe, effect extended away from plants

Aloe as facilitator1. Quantification of spatial pattern

(circumstantial evidence)2. Basic experimentation on species

interactions (does aloe facilitate other species?)

3. Establishment of dryland agriculture and range restoration program

• Growing and planting Aloe and Cenchrus on Massai group ranch; hope to harvest Aloe sap as cash crop and graze between rows.

Your turn…• List management issues/projects you

know of in range and forest ecosystems.

• Which of the ecological processes or interactions we have discussed so far do you need to understand?

• Can you make predictions or recommendations based on your understanding of the ecological systems?

Future lectures…• 10 minutes at beginning of class for

students to present case studies pertaining to previous lecture’s topic.

• Start Wed – topic is measurement and definition of communities…

Community: working definition

• Two concepts: continuum or community type

• Continuum – vegetation changes along gradients of environmental conditions. Species may co-occur by chance/shared environmental tolerances.

• Community type – species occur in association, such aggregations have adaptations holding them together as units. Show boundaries between them.

Community: working definition

These two concepts are not mutually exclusive; both patterns occur to a greater or lesser

extent in natural vegetation. Sharpness of community boundaries often relate to abrupt changes in site conditions (e.g. serpentine soil

patch).

Community best thought of as a “level of organization” rather than a distinct entity with

boundaries.

Community: working definition

• Visually distinct features of a landscape. • Interpreting composition, stand structure,

dynamics, and spatial distribution requires understanding of site conditions, disturbance, history, and ecological processes. Barnes et al 1998.

• Forest type – a community defined solely on the basis of canopy species

• Ecotone – transition area between two community types. e.g. grassland and forest: broad change in community due to longer term climate/environment BUT exact position of treeline depends on local disturbance, competition, history, etc.

Community attributes• Physiognomy

– Architecture, LAI, life-forms, phenology, etc.• Composition, spatial pattern, and diversity• Nutrient cycling

– Demand, storage, rate of cycling, efficiency• Productivity• Control of environment

– Plant-environment feedback• Change over time

– Succession, stability, migration

Community structure• Physiognomy – physical structure of

vegetation (appearance, structural complexity, architecture, growth forms)

• Why is vegetation structure important?

Community structure• Leaf Area Index – LAI.

– Square meters of leaf area per square meter of ground.

– Higher LAI, usually more sunlight intercepted, greater efficiency and productivity. e.g. tropical forest LAI=11, uses 1.5% incident radiation, desert LAI=1, uses 0.04% incident radiation.

Life forms• Characteristic structure of plant…life

form will affect disturbance tolerance, physical structure, regeneration, etc.

• Raunkiaer (1934) classified plants based on location and protection of meristems and/or reproduction (see handout).

Community composition• Communities composed of species…

are all species necessary to define a community?

• Biodiversity:– What is biodiversity?– What does diversity signify? Why is it

important?– Types of diversity: richness, evenness,

functional diversity…others?

Patterns of diversity• Species and individuals distributed in

different ways in different communities.

• Spatial patterns – alpha diversity – diversity or richness in

species within a habitat– Beta diversity – diversity of habitats in an

area; “species turnover”– Gamma diversity – diversity of a region

Upcoming lectures• Next lectures will address aspects of

communities and diversity concepts: – Mar 3: productivity– Mar 8-9: plant-soil interactions, nutrients– Mar 10: disturbance and succession– Mar 22: state and transition dynamics– Mar 24: fire ecology and climate change– Mar 29: functional groups and biodiversity

Example of community description

• Ecological sites – BLM, USFS, and NRCS• Used for both range ecological sites and forest

ecological sites.• Details of range site description given in handout• Details of forest site description given in national

Forestry Manual: • ftp://ftp-fc.sc.egov.usda.gov/NSSC/

National_Forestry_Manual/2002_nfm_complete.pdf

• Range and forest type sites are differentiated by HISTORIC VEGETATION.

Ecological site• Definition: A distinctive type of land

with specific physical characteristics that differs from other types of land in it’s ability to produce a distinctive kind and amount of vegetation.

• Clementsian?

Ecological site description• Vegetation is product of:

– Soils– Topography– Climate– Disturbances

• Differentiated by:– Differences in dominant plant species– Changes in proportion of plant species– Changes in productivity

Ecological site description• Utility of site descriptions…

“Rangeland landscapes are divided into ecological sites for the purposes of

inventory, evaluation, and management”