1. Biodiversity and DGVMs I. Colin Prentice, QUEST Silwood Park 2 June 2009

2. What (some) DGVMs can do (reasonably) well Global carbon and water cycle properties (yes), feedbacks (maybe) Broad-scale biogeographic patterns Global patterns of trace gas emissions (including fires)

3. Carbon and water cycling in LPJ Photosynthesis from simplified Farquhar model with optimized V cmax Stomatal conductance maintains constant c i /c a when E max * W/W max not exceeded, else is adjusted to maintain this rate of ET ET from Monteith (1995): Priestley-Taylor, modified by stomatal conductance

4. PN Foster et al. (work in progress)

5. Xu-Ri et al. (work in progress)

6. Limitations of DGVMs (1) PFTs are too few (5-10) => “plasticity dilemma” Attribution of generic “literature values” for traits No fundamental explanation for niche space of each PFT => Divergent predictions of “biome shifts” (vegetation structural changes)

7. Limitations of DGVMs (2) Poor representation of functional diversity within communities Life history trade-offs (e.g. leaf economics spectrum) not modelled => Compositional responses to environmental variability and change probably wrong => Potential for wrong biogeochemical responses as well?

8. Can DGVMs reliably predict responses to climate change on decadal-centennial time scales?

9. Probably not

10. Can DGVMs reliably predict responses to climate change on decadal-centennial time scales? Probably not Iconic example: “Amazon die-back”

11. Relevant scientific advances for next generation DGVMs Rediscovery of functional morphology Link between plant hydraulics and photosynthesis Recognition of biophysical constraints and trade-offs Application of economic approaches to plant function and co-existence Comparative data to test hypotheses and assign functional properties to PFTs

12. Next steps for DGVMs Define a small set of model parameters for a plant Define a pathway from widely measured traits to fundamental variables in models

13. The List (to be developed.....) wood anatomy/densitysapwood permeability leaf hardnesswilting point leaf size/dissectionboundary-layer conductance  13 Cc i /c a “operating point” bark thicknessfire resistance.....

14. Conclusion: including biodiversity in DGVMs Characterize functional variation among species in terms of processes A longer list of PFTs: sample from a continuum of traits, allowing for trait covariation Exploitation of quantitative trait data at species level [TRY data base] New benchmarks for DGVMs: compositional transects, climate responses... [BBS project]