How biodiversity underlies ecosystem services in terrestrial systems

Transcription

1 ITAL How biodiversity underlies ecosystem services in terrestrial systems Sandra LAVOREL Laboratoire d Ecologie Alpine Centre National de la Recherche Scientifique (CNRS), Grenoble, France Research priorities to sustain Ecosystem Services Conference of the European Platform for Biodiversity Research Strategy Budapest, 27 April 2011

2 What good is biodiversity for humans? Nothing! Intrinsic value of nature Essential for life on Earth Role of biodiversity for ecosystem functioning and the biosphere Services to society Nature s contributions to individual et collective well-being New objectives : Accounting for nature s services in private and public decisions

3 Presentation overview The role of biodiversity in ecosystem service provision Review of evidence from temperate agroecosystems Quantifying the spatial distribution of ecosystem services Functional ecological production functions for ecosystem services Synergies and trade-offs among ecosystem services and their biophysical basis Can we preserve biodiversity by focusing on ecosystem services? Research challenges

4 Ecosystem Services The benefits people obtain from ecosystems Millennium Ecosystem Assessment 2005

5 Demystification of ecosystem services Structure(s) or process(es) Grass species Nutrient cycle Function(s) Green biomass Phenology Crude protein content Feedback effects of human actions Service(s) Fodder production Grasses for grazing Human input(s) Benefit(s) Harvest fodder Grazing Cheese or meat de Grootet al, 2002, Teeb 2009, Haines- Young & Potschin(2010) Ecological structure, habitat, ecosystem properties and supporting services The potential that ecosystems have to deliver a service. Things needed to deliver services the direct and indirect contributions of ecosystem to human well being Welfare gains generate MA, 2005 Supporting services Benefits people obtain from ecosystem Daily (ed), 1997 Complex natural cycle The conditions and processes through which natural ecosystems, and the species that make them up, sustain and fulfill human life 5 Lamarque et al, Comptes Rendus Biologies

6 What is an ecosystem service? Structure(s) or process(es) Grass species Nutrient cycle Function(s) Green biomass Phenology Crude protein content Service(s) Fodder production Grasses for grazing Human input(s) Benefit(s) Harvest fodder Grazing Cheese or meat Ecological components Social components Lamarque et al, Comptes Rendus Biologies

7 Ecosystem services mapping studies often use land use / land cover ES identity Source of uncertainty in estimates of ecosystem services Eigenbrod et al. J. Appl. Ecol. 2010

8 Components of biodiversity Diaz et al. PLoS 2006

9 Effects of different biodiversity components on ecosystem services Diaz et al. PLoS 2006

10 Quantifying the effects of biodiversity on ecosystem services: Methodology Ecosystem service Soil fertility Ecosystem processes Decomposition Mineralisation Plant use Organism or landscape structure: Species diversity, identity; Functional diversity, identity; Trophic complexity Spatial heterogeneity Plants Soil fauna Soil microorganisms

11 Ecosystem services in agroecosystems MARKET PRODUCTION INPUT SERVICES Soil structure Water availability Fertility Microclimate Biotic control Invasion control Pollination Livestock health Lavorel et al Modified from Zhang et al AGRO- ECOSYSTEMS Primary production: - Efficiency - Stability: biotic controls - Stability: abiotic variability - Fodder production stability Livestock production: - Efficiency - Fodder quality - Quality of animal products Other marketable products ADDITIONAL PRODUCTION Water production Water quality Climate regulation Fire regime regulation Human health Biodiversity conservation Cultural & aesthetic value

12 Input services (1) Ressources for production Soil nitrogen concentration + legumes 0 legumes Litter decomposition Net effet of diversity Number of species Grassland or crop plants: Plant species richess increases nitrogen use, but this effect is mostly that of legumes Functional dissimilarity Soil macrofauna : In presence of several functaional groups (earthworms, isopods, chilopods) species number has no effect on decomposition. Functional diversity is the driving variable. => Role of functional diversity for the maintenance of fertility, but these effects are relevant only when fertilisation is low / organic

13 Input services (2) Biotic regulation : Pollination Observed wild bees Distance to grassland (m) The abundance of wild bees decreases with the distance from plants (crops) to be pollinated to semi-natural grasslands - pollinator sources Number or seeds / fruit Distance to grassland (m) The increase in abundance and diversity of pollinators near grassland results in increased fruiting => Importance of maintaining sources of pollinators in the landscape

14 Production (1) Crop yields Yield Number of species Corn Soybean Crop rotation experiment: - Variation of the numberof species in the rotation and of the number of legume species used as cover crops - No fertiliser or pesticides Wheat Total yield of the rotation - Doubling of corn yield ~ mean regional yield. - Less clear for other crops. - Improved nitrogen resources but no effect on weeds except in wheat Smith et al. 2008

15 Plant production (2) Stability Coefficient of variation of aboveground biomass Number of sown species Number of sown species - Decreased interannual variability in the face of climate variability? - As many experiments find a positive effect of grassland richness as not, without an understanding of causes. - Grassland yield stability through variation of yields of individual species. - Appears to promote stability of fodder production at farm scale. No clear evidence for the insurance hypothesis

16 Non-marketable services Aesthetic and cultural values Butterfly diversity Small-scale heterogeneity Conventional agriculture Organic farming

17 Main effets of biodiversity on ecosystem services provided by temperate agroecosystems Dominant species and their functional characteristics Input services soil stability, fertility, water availability Yield of permanent grasslands and benefits for animal production Services at larger scales: water quality, climate regulation, fire mitigation. Functional complementarity Fertility, yields: legumes grasses; crop rotation Soil stability, water availability, yields: plant species with differing morphology, phenology or rooting depth Fertility: soil macrofauna but remains to be elucidated for most services Ex. effects of species diversity of biocontrol agents and pollinators Role of spatial diversity in landscapes Executive summary and synthesis report on temperate agroecosystems available at:

18 Challenge 1 At which scale should biodiversity be managed to accrue ecosystem services? Relative benefit of biodiversity to the service Biotic regulation input services extensive intensive Landscape-scale Relative benefit of biodiversity species richness to the service extensive intensive Resource input services Type Landscape de paysage type Birds, plants with long dispersal Highly mobile insects Landscape Type de paysage type Landscape type Soil fauna and microorganisms, plants with limited dispersal, Insects with restricted mobility

19 Challenge 2 Understanding the effects of management on multiple ecosystem services through their effects on biodiversity - Synergies and trade-offs across ES Example: Services from plant and microbial diversity in permanent grasslands Services Management intensity Fodder production; milk production Maintenance of fertility Animal health, ingestion, cheese quality, water quality

20 Biodiversity and multi-fonctionality: Example of agroforestry Traditional agroforestry Modern agroforestry

21 Challenge: Using ecological knowledge to understand ecosystem services trade-offs and synergies Fertilisation, mowing Intense grazing Abandonment Resource conservation: leaf life span, nutrient and water use efficiency, C-based defenses Resource acquisition: specific leaf area, specific root length, tissue [N] PLANT Slow biogeochemical cycles Litter accumulation Low palatability Carbon sequestration Soil conservation Pest control Lavorel & Grigulis in prep. Fast biogeochemical cycles High NPP High palatability Fodder production Soil nutrient supply Invertebrate diversity FUNCTION SERVICES

22 Quantifying ecosystem services based on land use Topography Land use DIRECT EFFECTS Soil properties Biodiversity effects = INDIRECT EFFECTS Ecosystem properties Plant diversity Biodiversity responses

23 Quantifying ecosystem services accounting for biodiversity effects ITAL Land management Topography DIRECT EFFECTS Soil properties Biodiversity = INDIRECT EFFECTS Ecosystem properties Plant diversity Biodiversity responses Lavorel et al. J. Ecol. 2011

24 Quantifying ecosystem services depending on land use and species functional traits at Lautaret (France) Summer range Permanent grasslands (mowing) Mowing Summer grazing Terraces (crops) Mowing & fertilised Mowing & unfertilised Spring+autumn grazing

25 Production functions of ES incorporating functional diversity effects Fodder quantity Fodder quality Flowering phenology Plant height Leaf Nitrogen Conc. Plant height Leaf Dry Matter Content Date of flowering Phenological diversity Sum of mapped values for each contributing Ecosystem Property Grassland agronomic value ITAL

26 Trade-offs and synergies in ES provision Methods for quantitative analysis of spatial association among services Counts of number of ES provided per pixel ES hot spots, cold spots etc. Overlap analyses Multivariate analyses

27 Counts of overlapping ecosystem services Willemen et al. Ecol. Ind. 2009

28 Lavorel et al. J. Ecol Mapping multiple ecosystem services Agronomic value Cultural value Pollination value Soil C stocks Regulation value Total ES value

29 Overlap analyses Analyse spatial overlap among areas of provision for different services Chan et al. PLoS Biology 2006 Sensitivity to threshold of ES provision determined by decision makers comparing 3 perspectives Agronomic Aesthetic Conservation Gos & Lavorel in prep.

30 Multivariate analyses of Trade-offs and Synergies in ES provision Principal component analysis Factor Grazed summer grasslands * * * * * * * ** Crude Protein Content * * * * FD Flowering Onset * * Litter Mass * * * * * * Soil Plant Carbon Diversity * * * * ** * Mown Festuca * * * * grasslands Green Biomass * Unfertilized + mown terraces Fertilised + mown terraces Unfertilized + unmown terraces Unmown Festuca grasslands Factor 1 (58% variance) Lavorel et al. J. Ecol Cultural heritage value

31 Challenge 3: Trade-offs and synergies in ES provision in space and time Services trade-offs in space and time As a result of land use change (scenarios + past) In time: specify time scales for different ES; need method for trading off e.g. time discounting model from restoration ecology In space: Build on analysis of hot spots and spatial comparison between provision and demand Larger scales: import of ES from outside the modelling geographic domain (EU)

32 Trade-off analysis for land use scenarios (SENSOR) Paracchini et al. Ecol. Ind. 2009

33 Using discounting methods to assess temporal trade-offs

34 Challenge 4: Biodiversity and Ecosystem Services How do they overlap? Egoh et al. Biol. Cons Targeting ecosystem services directly can meet the multiple ecosystem services and biodiversity goals more efficiently but cannot substitute for targeted biodiversity protection (biodiversity losses of 44% relative to targeting biodiversity alone). Chan et al. PLoS Biol. 2006

35 Conclusions Biodiversity has an intrinsic value, but also plays an essential role for the functioning of ecosystems and the provision of ecosystem services (ES) to society Strong determinism of ES by land use via its effects on biodiversity Research challenges: Scales of biodiversity management to sustain specific ES Biodiversity and multi-fonctionality: novel biophysical approaches to understanding synergies and trade-offs across services Trade-offs and synergies in ES provision in space and time Biodiversity and Ecosystem Services - How do they overlap? Implications for land management and policy

36 Thank you for your attention!

37 Mapping Ecosystem Services for the assessment of alternative land use scenarios Nelson et al FREE

38 Input services: (3) Pest biocontrol Field edges Within fields Grass strips + woody species Agroforestry Flower strips Beetle bank Managing complexity favours populations of control agents and decreases pest populations

39 Functional complementarity : Mechanisms for increased biomass production Corn yield(t/ha) Nb species in rotation Nb legumes Soil volume Smith et al Soil nitrogen concentration Soil volume Plant species richness increases nitrogen use, but this effect is dominated by that of legumes Dimitrakopoulos & Schmid 2004 Complementarity in root architectures: underlies the expression of species richness effects

40 Production (3) Animal production Composition of ingested biomass Digestibility (%) Digestibilité (%) Diversity of fodder Teneur en parois végétales (g/kg DM) Stade de développement > 70% Graminées > 50% et < 70% de graminées et riche en RGA > 50% dicotylédones et riches en plantes feuillues > 50% dicotylédones et riches en plantes à tiges fibreuses Increased quality of products: Increased sensory quality of mountain cheeses (10 studies)

41 Non-marketable services : (1) Water quality Decrease in genetic diversity by dilution of the denitrifying community No effect on denitrification: Strong functional redundancy among soil microorganisms Density denitrifying bacteria Wertz et al. 2007

42 Which benefits can agriculture draw from biodiversity? Benefits of biodiversity: Small with respect to short-term production losses for inputs relating to ressources Strong if not irreplaceable for input services relating to biotic regulation Plant and animal production can benefit from these services given adapted management (farmer technicity) Key services for society outside of direct farm income Keys for sustainable agriculture: To better understand and manage functional diversity To manage landscape diversity To understand and negociate synergies and trade-offs between services Feasibility and acceptability to farmers

43 Limits of knowledge and research priorities Interests and limits of manipulative experiments using assembled communauties Strong heuristic contribution, but results remain to be validated under agronomic conditions Limited levels of manipulated diversity; species and functional group identity, community structure Interactions with factors that are actually manipulated by management: fertilisation, disturbance Long-term experiments, including agronomic experiments Majority of studies: effects on plant diversity on plant production Roles of other organisms and range of services associated with agroecosystems: soil, pollinators, pest biocontrol agents Role of biodiversity for production and agroecosystem stability poorly studied Spatio-temporal dimension of biodiversity: Dynamics of recolonisation after local extinction in the context of agricultural landscapes Ecosystem engineering Modelling to access larger / longer scales Amplitude of biodiversity effects with respect to those of exogenous inputs, and actual value to the farmer in terms of savings on inputs and yields

44 Species-level functional traits: Fodder digestibility Relation between digestibility and (A) growing degree days to flowering, (B) leaf dry matter content for 13 grass species from permanent grasslands grown in monocultures Species traits determine digestibility Relationship confirmed at community level (weighted mean): Garnier et al. unpublished Pontes et al. 2007

45 Community weigthed mean traits: Soil water availability Gross et al. New Phytol 2008