Outline

• Community Ecology– Indirect effects, Keystone species, Invasive species

– Biodiversity: importance and evaluation

– The new paradigm in ecology: communities in flux

– Conservation of species interactions

• Ecosystem Ecology– Ecosystems of special concern (Marine and Tropical)

– Biodiversity and ecosystem services

– Ecosystem services

Biodiversity and Ecosystem FunctionE

cosy

stem

F

unct

ion

Species Richness

redundantrivetidiosyncratic

Biodiversity and Ecosystem Function: Ecotron Experiments

Biodiversity and Ecosystem Function: Ecotron Experiments

Naeem, S., et al. 1995. Empirical evidence that declining biodiversity may alter the performance of terrestrial ecosystems. Phil. Trans. R. Soc. Lond. B. 249-262.

Predators

Herbivores

Plants

Decomposers

9 spp. 15 spp. 31 spp.

Biodiversity and Ecosystem Function: Ecotron Experiments

• Productivity was highest in high diversity communities and lowest in low diversity communities

• Below ground decomposition was not different between treatments

• Water retention was different between treatments, but with no clear relationship to biodiversity

Biodiversity and Ecosystem Function: Ecotron Experiments

• Depending on ecosystem process considered, results supported each hypothesis for the relationship between diversity and function

Biodiversity and Ecosystem Function: BioCON

Biodiversity and Ecosystem Function: BioCON

Biodiversity and Ecosystem Function: BioCON

Evenness and Ecosystem Function

•Wilsey, B.J. and C. Potvin. 2000. Biodiversity and ecosystem functioning: importance of species evenness in an old field.

Kentucky bluegrass, dandelion, and wild strawberry planted at 3 levels of evenness (1.5:1:1, 5:1:1, 12:1:1)

Evenness

Biodiversity and Ecosystem Function:Some Caveats

• Tilman (26 spp.)

• Wilsey (3 spp.)

• Naeem (31 spp.)

• Reich (16 spp.)Tilman, D. 1996. Biodiversity: Population versus ecosystem stability. Ecology 77: 350-363.

Conclusions: Diversity and Ecosystem Function

• Plant production may decline as regional and local diversity declines

• Ecosystem resistance to environmental perturbations, such as drought, may be lessened as biodiversity is reduced

• Ecosystem processes such as soil nitrogen levels, water use, plant productivity, and pest and disease cycles may become more variable as diversity declines.

From: Biodiversity and Ecosystem Functioning: Maintaining Natural Life Support Processes. Naeem, S. et al. Issues in Ecology Report 2, Ecological Society of America

http://esa.sdsc.edu/issues.htm

Ecosystem Services• purification of air and water

• mitigation of droughts and floods

• generation and preservation of soils and renewal of their fertility

• detoxification and decomposition of wastes

• pollination of crops and natural vegetation / dispersal of seeds

• cycling and movement of nutrients

• control of the vast majority of potential agricultural pests

• maintenance of biodiversity

• protection of coastal shores from erosion by waves

• partial stabilization of climate / moderation of weather extremes

From: Ecosystem Services: Benefits Supplied to Human Societies by Natural Ecosystems. G.C. Daily et al. Issues in Ecology Report 4, Ecological Society of America

http://esa.sdsc.edu/issues.htm

Lyme Disease

Ecosystem Services:The Dilution Effect