1. Does biodiversity play a significant role in ecosystem function? ASB Sustainable Land Use Mosaic (SLUM) Working Group Symposium 12-15 November 2001 Chiang Mai, Thailand CBM

2. Definitions Biodiversity Conceptual: The variety of life on earth expressed in terms of gene, species and ecosystem. (cf. Heywood & Baste, 1996) Operational: The quantity and composition of species and functional types recordable in any area. (Gillison, 2001). Functional types: (FTs) are sets of organisms showing similar responses to environmental conditions and having similar effects on the dominant ecosystem processes. (Diaz, 1998). ASB SLUM Mtg Chiang Mai 11 Nov 01

3. Diversity …The number of different items and their relative frequency. For biological diversity these items are organized at many levels …. Thus the term biodiversity encompasses different ecosystems, species, genes and their relative abundance. (US Congress, Office of Technology Assessment, 1987). ASB SLUM Mtg Chiang Mai 11 Nov 01

4. Indicators and surrogates The vast number of biota that influence ecosystem function are mainly small organisms that are very difficult to measure. For most practical purposes their diversity and that of other larger, difficult-to-measure organisms, is assumed to be indicated by more readily observable units such as plant species and functional types. (This tends to be an act of faith commonly applied in private and denied in public). ASB SLUM Mtg Chiang Mai 11 Nov 01

5. Ecosystem 1.A community of interdependent organisms together with the environment which they inhabit and with which they interact. (Allaby, 1977). 2. A functional system which includes the organisms of a natural community together with their environment. (Lapedes, 1976) 3. … the sum total of vegetation, animal, and physical environment in whatever size segment of the world is chosen for study. (Fosberg, 1967) ASB SLUM Mtg Chiang Mai 11 Nov 01

6. The ecosystem concept is used widely but ambiguously. It can: a)contain only a functional meaning, b)have a spatial connotation which includes any level of scale or c)the spatial aspect can be included, but additionally, relative homogeneity must characterize the system (Johnson and French, 1981, quoted by Godron & Forman, 1983) ASB SLUM Mtg Chiang Mai 11 Nov 01

7. Differences between ecosystem and landscape: Ecosystems: are relatively homogeneous Landscapes: are relatively heterogeneous. A landscape is “… a kilometers wide area where a cluster of interacting stands or ecosystems is repeated in similar form” (Godron & Forman, 1983) ASB SLUM Mtg Chiang Mai 11 Nov 01

8. ‘Ecosystem’ conversion to ‘landscape’ ASB SLUM Mtg Chiang Mai 11 Nov 01

9. Landscape assemblages In NW Mato Grosso, Western Amazon basin Brazil ASB SLUM Mtg Chiang Mai 11 Nov 01

11. Differing views of species role in ecosystems 1. Systematists and population biologists: –No two species can exist in exactly the same habitat –Every species has a unique resource requirement and hence use pattern ASB SLUM Mtg Chiang Mai 11 Nov 01

12. 2. Ecologists 2. Ecologists: –More than one species can occupy a functional type or resource niche (e.g. mesophyte, xerophyte, producer, consumer, life form, C 3, C 4 path, nitrogen fixer, PFT…) –More than one functional type can occur within a species.

13. Approaches to species, biodiversity and ecosystem function: Traditional: Community ecology: Species diversity is a dependent variable controlled by abiotic conditions and ecosystem constraints. Ecosystem ecology: Dominant species control ecosystem properties. Recent: Now consider role of biodiversity as a potential modulator of ecosystem processes. ASB SLUM Mtg Chiang Mai 11 Nov 01

14. Some general assertions Ecosystem stability and primary productivity vary directly with diversity in species and functional type Species properties expressed as functional types exert a greater degree of control on ecosystem function than species diversity (richness) ASB SLUM Mtg Chiang Mai 11 Nov 01

15. (After Springett, 1976) ASB SLUM Mtg Chiang Mai 11 Nov 01 See also Swift & Anderson (1993)

16. Biodiversity and ecosystem function: Recent consensus* Some minimum number of species is essential for maintaining ecosystem function under constant conditions A larger number of species is probably required for maintaining ecosystems in changing environments Determining which species have significant impact on which processes in which ecosystem remains an open emiprical question *Loreau et al. (2001) ASB SLUM Mtg Chiang Mai 11 Nov 01

17. Cont.. Increased primary production via higher plant diversity can be expected to stimulate secondary productivity. Changes in one trophic level may lead to a variety of potential responses for processes at higher trophic levels. Mechanisms for generating primary productivity may range from systems with a few dominant species or functional types (low diversity) to systems with high diversity, low level dominance and high complementarity (synergy). ASB SLUM Mtg Chiang Mai 11 Nov 01

18. Hypothetical mechanisms involved in biodiversity experiments using synthetic communities Loreau et al. (26 October, 2001) Science: 294:804-808

19. Primary productivity Diversity of Spp and FTs Low High (few groups) Low (many ‘ rare’ ) Complementarity low High Local, regional, random processes. Within and between landscape heterogeneity high Local, deterministic processes. Niche diff’n high. Within landscape heterogeneity low ? Dominance Dual hypothetical mechanisms for species, FT diversity and ecosystem productivity ASB SLUM Mtg Chiang Mai 11 Nov 01

20. Function/ ProcessAction Nutrient capture Decomposition and soil formation Mycorrhizal activity Photosynthesis Herbivory Pollination Species interactions (mutualisms, symbiosis, predation, parasitism, competition) Water uptake and loss Source: Hobbs (1992) See also Giller et al. ( 1997 ) for below-ground Nutrient cycling Enhanced nutrient uptake Energy capture and productivity Energy and nutrient capture Genetic information transfer Energy, water and nutrient transfer Water transfer Ecosystem functions and processes related to the transfer of energy, nutrients, water and genetic information ASB SLUM Mtg Chiang Mai 11 Nov 01

21. Plants as basal ecosystem units Most terrestrial (mobile, heterotrophic) biota ultimately depend on plants for survival Plants as mostly sessile, autotrophic units are readily observable in nature Variation in plant form and function is measureable along key environmental gradients ASB SLUM Mtg Chiang Mai 11 Nov 01

22. Water High Medium Low Light (energy) Low Medium High ASB SLUM Mtg Chiang Mai 11 Nov 01

24. Plant Functional Types* Photosynthetic envelope (leaf size, inclination, chlorotype, morphotype) Physical support system or life form based on position of perennating buds Above-ground rooting system Minimum set of attributes ‘Coherent’ functional model * after Gillison (1981) ASB SLUM Mtg Chiang Mai 11 Nov 01

25. VegClass, Windows-based, user-friendly software for data entry and meta-analysis; integrated with field proforma to support rapid vegetation survey

26. Plant Functional Types: leaf + stem photosynthesis, incl. parasites, carnivores ASB SLUM Mtg Chiang Mai 11 Nov 01

27. Function/ ProcessAction Nutrient capture Decomposition and soil formation Mycorrhizal activity Photosynthesis Herbivory Pollination Species interactions (mutualisms, symbiosis, predation, parasitism, competition) Water uptake and loss * PFT relevance highlighted in red Nutrient cycling Enhanced nutrient uptake Energy capture and productivity Energy and nutrient capture Genetic information transfer Energy, water and nutrient transfer Water transfer Ecosystem functions and processes related to the transfer of energy, nutrients, water and genetic information* ASB SLUM Mtg Chiang Mai 11 Nov 01

28. Patterns of richness in plant species and functional types under different land use types Indonesia : Jambi - Lampung Legend Cassava Imperata Mono. Plantation Agroforestry Logged Forest Natural Forest Plant FunctionalTypes (modi) ASB SLUM Mtg Chiang Mai 11 Nov 01

29. 024681012141618202224 Basal Area m 2 ha -1 0 10 20 30 40 50 60 70 80 90 100 Termite Abundance Regression plot of termite abundance & basal area of woody plants [r 2 =0.985] over 7 land use systems: Jambi BS Nov. 97 Primary Forest Secondary Forest Imperata Cassava Rubber Plantation Jungle Rubber Paraserianthes Plantation ASB SLUM Mtg Chiang Mai 11 Nov 01

30. Termite species richness Primary Forest Secondary Forest Imperata Cassava Rubber Plantation Jungle Rubber Paraserianthes Plantation Ratio of plant species richness to plant functional types as an indicator of Termites species richness [R-Sq = 0.97] over 7 land use systems : Jambi BS Nov. 97 Ratio of plant species to plant functional types (modi) ASB SLUM Mtg Chiang Mai 11 Nov 01

32. Above-ground carbon and species: PFTs along a gradient of Land Use Types, Jambi [r 2 = 0.814] 1.01.21.41.61.82.02.22.42.62.83.0 0 10 20 30 40 50 60 1 2 5 4 10 11 3 9 8 6 7 15 13 16 1412 AG-carbon Species : PFTs (Y=13.56  23.52X + 11.30 X**2) ASB SLUM Mtg Chiang Mai 11 Nov 01

33. Aboveground Carbon and Species:PFTs All ASB benchmark sites Plant Spp:PFT ratio Aboveground - C t/ha Primary Forest Managed Forest Tree-based Fallow Crop Pasture

35. Conclusions Specific knowledge of functional types may be essential to predict ecosystem responses under different global scenarios or where management seeks to manipulate species composition directly as in complex agroecosystems. Hypotheses and models must be tested in a wider array of ecosystem types e.g. tropical forests. To predict and understand changes in biodiversity and ecosystem function we need to move beyond simple causality and address multiple feedbacks. Relationships between local, landscape and regional scales require critical attention. ASB SLUM Mtg Chiang Mai 11 Nov 01