Biodiversity and Functioning of Terrestrial Ecosystems

Lucie Zinger UMR 8197 IBENS – Institut de Biologie de l'École Normale Supérieure, 46 rue d’Ulm, 75005, Paris. [email protected]

The 6th biodiversity crisis? Terrestrial Living Planet Index (LPI)

➡

Global trend of populations decline of ca. 38% in the last 40 years (ca. -1.1% y-1) WWF. Living Planet Report (2016). Risk and resilience in a new era. WWF International, Gland, Switzerland

The 6th biodiversity crisis? Extinction rates (per 1000 species per 1000 year)

Millennium Ecosystem Assessment (2005). Ecosystems and Human Well-being: Biodiversity Synthesis. World Resources Institute, Washington, DC.

The “Great Acceleration” in human activities

WWF. Living Planet Report (2016). Risk and resilience in a new era. WWF International, Gland, Switzerland

Synergetic effects Agriculture

Industry

Human Activities Urbanization International trade

- Habitat degradation, fragmentation, or loss - Pollution - Overexploitation

Invasive species and diseases

Climate change

Biological diversity loss

Groom, M. J., Meffe, G. K., & Carroll, C. R. (2006). Principles of conservation biology (pp. 174-251). Sunderland: Sinauer Associates.

Main threats to terrestrial biodiversity Threat type frequency for declining terrestrial populations (LPI)

WWF. Living Planet Report (2016). Risk and resilience in a new era. WWF International, Gland, Switzerland

Future projections Predicted net loss in local species richness caused by land use and related pressures for 2090

… lower bound estimates? WWF. Living Planet Report (2016). Risk and resilience in a new era. WWF International, Gland, Switzerland

Cascading effects? Apex predators

Absent

Present

Bottom-up regulation

Herbivore density

Plant density

Top down regulation Terborgh, John, et al. (2001) "Ecological meltdown in predator-free forest fragments." Science 294.5548: 1923-1926. Review in Estes, James A., et al. (2011) "Trophic downgrading of planet Earth.” Science 333.6040 : 301-306.

Why it matters: ecosystem sustainability Joseph Priestley (1733-1804)

The Priestley Jar Experiment

Unsustainable system

Sustainable system

Adapted from Naeem. S.; Gorham, E. (1991). Biogeochemistry: its origins and development. Biogeochemistry, 13(3), 199-239.

Why it matters: ecosystem sustainability Joseph Priestley @priestleyJ ‧ Jun 1772 it is highly probable, that the injury which is continually done to the atmosphere by the respiration of such a number of animals, and the putrefaction of such masses of both vegetable and animal matter, is, in part at least, repaired by the vegetable creation. […] […] the putrid effluvium is in some measure extracted from the air, by means of the leaves of plants that render the remainder more fit for respiration Benjamin Franklin @BenFranklin ‧ Jun 1772 Replying to @priestelyJ That the vegetable creation should restore the air which is spoiled by the animal part of it, looks like a rational system, and seems to be of a piece with the rest. […] I hope this will give some check to the rage of destroying trees that grow near houses, which has accompanied our late improvements in gardening…

Donald J. Trump

@realDonaldTrump ‧ Mar 2017

[…] We’re going to have clean water. We’re going to have clean air, but so many [environmental regulations] are unnecessary. So many are job-killing. 13K

105K

68K

Adapted from Naeem. S.; Gorham, E. (1991). Biogeochemistry: its origins and development. Biogeochemistry, 13(3), 199-239.

Why it matters: ecosystem sustainability

Biodiversity perspective

Ecosystem perspective

Adapted from Naeem. S.; Gorham, E. (1991). Biogeochemistry: its origins and development. Biogeochemistry, 13(3), 199-239.

Why it matters: ecosystem sustainability Ecosystem perspective Biodiversity perspective

Gravel D., Gounand I. et Mouquet N. (2010). Le role de la diversite dans le fonctionnement des Ecosystemes. Ciencia Ambiente 39.

An anthropocentric perspective Linkages among Biodiversity, Ecosystem Services, and Human Well-being

Millennium Ecosystem Assessment (2005). Ecosystems and Human Well-being: Biodiversity Synthesis. World Resources Institute, Washington, DC.

Need to describe, understand, and predict

high

low

Vascular plant diversity

low

high

?

C pools in soils

low

high

Biodiversity-Ecosystem Functioning Research (BEF) How is the biodiversity per se within an ecosystem related to the ecosystem’s function, its stability and sustainability?

Midgley, G. F. (2012). Biodiversity and ecosystem function. Science, 335(6065), 174-175.

The wedding of two disciplines Ecosystem Ecology • Functioning • Fluxes of energy and materials • Physical and geochemical constraints ➡ Macroscopic perspective ➡ Regularity, predictability ✓ Inductive generalisation - Theory & hypothetico-deductive approaches

Population/Community Ecology • Abundance and diversity • Structure and dynamics • Abiotic and biological constraints ➡ Microscopic perspective ➡ Variability ✓ solid theoretical framework & hypothetico-deductive - Hypotheses testing & generalisations Naeem, Shahid, J. Emmett Duffy, and Erika Zavaleta (2012): The functions of biological diversity in an age of extinction. Science 336.6087 1401-1406.

A tumultuous story ~350 BC Aristotelian perspective:

all entities share commonalities and traits

~1500

“The Scientific Revolution”: new technologies & rationalisation.

1859 Darwin’s “Principle of Divergence”: a BEF hypothesis premise Communities composed of organisms developed under many and widely differing forms should have higher rates of productivity and decomposition (“Big Species Book”)

~1900

Fragmentation of sciences: “Natural sciences” ➡ distinct disciplines. 17 Naeem (2002). Ecosystem consequences of biodiversity loss: the evolution of a paradigm. Ecology, 83(6):1537-1552

A tumultuous story 1980s Increasing signs of biodiversity decline 1992

➡ Sustainable development Bayreuth conference: emergence of the BEF hypothesis ➡ Experiment testing BEF hypothesis ➡ BEF debate

2000

UN call for the Millenium Ecosystem Assessment

2001

Paris workshop “Biodiversity and Ecosystem Functioning: Synthesis and Perspectives”

present 18 Naeem (2002). Ecosystem consequences of biodiversity loss: the evolution of a paradigm. Ecology, 83(6):1537-1552

BEF main concepts • Biodiversity: the number and composition of the genotypes, species, functional types and landscape units in a given system. • Function: any activity, process or property of an ecosystem. • Stocks of energy and materials (e.g., biomass) • Fluxes of energy or material processing (e.g. productivity, decomposition) • Stability: dynamics of fluxes rates or stocks over time. • Persistance: temporal variability / predictability • Resistance: ability to persist in the same state in the face of a perturbation • Resilience: ability to return to its former state following
 a perturbation

Ecosystem process

BEF main early hypotheses

? Natural level

Biodiversity Loreau et al. (2002). Biodiversity and ecosystem functioning: Synthesis and Perspectives,Oxford University Press.

Niche complementarity hypothesis • Link to the niche theory: principle of competitive exclusion ➡ Species are functionally singular

Ecosystem process

➡ Increased ecosystem function through complementarity of e.g. resource use

Biodiversity Loreau et al. (2002). Biodiversity and ecosystem functioning: Synthesis and Perspectives,Oxford University Press.

Redundancy hypothesis

Ecosystem process

• Link to the neutral theory of biodiversity ➡ Species are functionally redundant

Biodiversity

➡ Insurance hypothesis: increased ecosystem stability through compensation of species loss • Depends on the type of environmental fluctuations. Loreau et al. (2002). Biodiversity and ecosystem functioning: Synthesis and Perspectives,Oxford University Press.

Idiosyncrasy hypothesis

Ecosystem process

• Species contribution to functioning depends on environmental conditions. ➡ Species impact is context-dependent

Biodiversity

➡ ≠ from the “null hypothesis”: species role too complex to be predictable. Loreau et al. (2002). Biodiversity and ecosystem functioning: Synthesis and Perspectives,Oxford University Press.

Cedar Creek Biodiversity Experiment, Minnesota, USA

168 plots of 9 x 9 m (35 replicates / level of diversity) No. of species of 1, 2, 4, 8 or 16 perennial grassland species

BIODEPTH experiment, Europe

480 plots in 8 countries No. of species of 1, 2, 4, 8, 16 or perennial grassland species

Biodiversity - Productivity Cedar Creek

BIODEPTH

➡ Generality of effects ➡ Niche related mechanisms (complementarity, facilitation, dilution) Review in Tilman et al. (2014) Biodiversity and Ecosystem Functioning. Annu. Rev. Ecol. Evol. Syst. 45:471–93

The debate • Sampling effect (Huston 1997): higher probability of including a species well adapted locally, productive, and/or that facilitates other species ➡ mixed culture behave like monocultures • Predictions from models of plant competition for one resource

N : number of individuals for species j R : density of resource aj : rate at which species j consume resource d: death rate of species j r : resource growth rate when not consumed

Tilman, D., Lehman, C. L., & Thomson, K. T. (1997). Plant diversity and ecosystem productivity: theoretical considerations. PNAS, 94(5), 1857-1861.

The debate • Sampling effect (Huston 1997): higher probability of including a species well adapted locally, productive, and/or that facilitates other species ➡ mixed culture behave like monocultures • Predictions from models of plant competition for one resource Best competitor model

Niche complementarity model

Tilman, D., Lehman, C. L., & Thomson, K. T. (1997). Plant diversity and ecosystem productivity: theoretical considerations. PNAS, 94(5), 1857-1861.

Complementarity vs. sampling effects Niche complementary effect

Sampling effect

➡ Complementary effects ≥ selection effects ➡ Increase of complementary effects through time ➡ Sampling effect: can occur in natura Cardinale et al. (2007) Impacts of plant diversity on biomass production increase through time because of species complementarity. PNAS 104(46):18123–18128

Biodiversity vs. Abiotic effects • Contradiction with empirical assessments Productivity

• BEF experiments: • Low environmental variability Species richness Species richness

• Empirical assessments: • Steep environmental gradients

Productivity/Fertility Adapted from Loreau, M., et al. (2001). Biodiversity and ecosystem functioning: current knowledge and future challenges. Science, 294(5543), 804-808.

Biodiversity vs. Abiotic effects • A matter of spatial scales Regional scale

Favorable soil and climate ➡ Higher interspecific competition

Productivity Local scale

Environmental heterogeneity ➡ Niche complementarity

Species richness

Unfavourable soil and climate ➡ Strong environmental filtering

Adapted from Loreau, M., et al. (2001). Biodiversity and ecosystem functioning: current knowledge and future challenges. Science, 294(5543), 804-808. Gravel D., Gounand I. et Mouquet N. (2010). Le role de la diversite dans le fonctionnement des Ecosystemes. Ciencia Ambiente 39.

BEF relationship: a pervasive form…

P: Productivity (m3 ha-1 yr-1)

• Global study with > 700,000 forest plots worldwide

Redundancy

Complementarity S: Tree species richness (%) Liang, J., et al. (2016). Positive biodiversity-productivity relationship predominant in global forests. Science, 354(6309), aaf8957.

… for multiple ecosystem functions • Does BEF relationship holds for soil C, N, and P storage and cycling in drylands?

242 plots distributed worldwide

Maestre, et al. (2012). Plant species richness and ecosystem multifunctionality in global drylands. Science, 335(6065), 214-218.

… for multiple ecosystem functions • BEF relationship for soil C, N, and P storage in drylands

Plant species richness (sqrt-transformed)

But sill, high amounts of unexplained variance…. Maestre, et al. (2012). Plant species richness and ecosystem multifunctionality in global drylands. Science, 335(6065), 214-218.

The species identity effect • Context dependency: effect of functional composition and diversity rather than species richness per se E = early-season annuals

P = perennial bunchgrasses

N = nitrogen fixers L = late-season annuals

Review in Tilman et al. (2014) Biodiversity and Ecosystem Functioning. Annu. Rev. Ecol. Evol. Syst. 45:471–93

The limits of taxonomic diversity • Species richness is not always a good surrogate of the number of functional groups present Aggregated occupation of niche space (common) Random or uniform occupation of niche space (uncommon)

Intra-specific functional variability

Dıa ́ z, S., & Cabido, M. (2001). Vive la difference: plant functional diversity matters to ecosystem processes. Trends in ecology & evolution, 16(11), 646-655.

The limits of taxonomic diversity

Functional diversity

Functional diversity

Functional diversity

• The relationship between functional and species diversity should influence the BEF relationship

Cadotte, M. W., et al. (2011). Beyond species: functional diversity and the maintenance of ecological processes and services. Journal of Applied Ecology, 48(5), 1079-1087.

Functional BEF? BIODEPTH

• Functional diversity > species richness effects on plant productivity

Cedar Creek

• Soil nutrient accumulation rates is mainly due to functional diversity Monocultures

C3+F C3+F+ All C4+L

Review in Tilman et al. (2014) Biodiversity and Ecosystem Functioning. Annu. Rev. Ecol. Evol. Syst. 45:471–93

A functional approach to biodiversity • Functional ecology is species blind Traits

Functions

Seed mass

Fecundity Dispersal Establishment

Canopy height

Light interception Competitive ability

Specific leaf area Leaf dry matter content Leaf N concentration

Resorption of nutrients Litter decomposability

Density, diameter Specific root length

Absorption (e.g. nutrients) Carbon fluxes (e.g. exsudation) Lavorel, S., & Garnier, E. (2002). Predicting changes in community composition and ecosystem functioning from plant traits: revisiting the Holy Grail. Functional ecology, 16(5), 545-556.

A functional approach to biodiversity • Cuts across levels of organisation

Violle, C., et al. (2007). Let the concept of trait be functional!. Oikos, 116(5), 882-892.

A functional approach to biodiversity • Cuts across levels of organisation • An example with the specific leaf area (SLA) Net photosynthetic rate (nmol CO2 g-1 s-1)

Relative growth rate (g g-1 d-1) Specific above-ground net primary productivity (g kg-1 d-1)

SLA (m2 kg-1)

Individual SLA (m2 kg-1)

Population SLA (m2 kg-1)

Community Violle, C., et al. (2007). Let the concept of trait be functional!. Oikos, 116(5), 882-892.

Functional traits relevant to BEF

25% variance explained

Global spectrum of plant form and function

45% variance explained

Díaz, S., et al. (2016). The global spectrum of plant form and function. Nature, 529(7585), 167-171

From functions to functional diversity? • Various measures of functional diversity… FAD Sum of distances Functional groups Trait Trait … 1 2 Sp A Sp B

Trait k

A

Traits values

Sp C Sp D

B

D

FGR No. groups

FDvar Trait variance CWM Trait weighted by species abundances

C

FD Total branch length

Adapted from Petchey, O. L., & Gaston, K. J. (2006). Functional diversity: back to basics and looking forward. Ecology letters, 9(6), 741-758.

From functions to functional diversity? • … with still some uncertainties FAD Sum of distances Trait Trait … 1 2 Sp A Sp B

Trait k

What hypothesis?

Traits values

FDvar Trait variance

Functional groups

A

Sp C Sp D

What metric?

What trait?

CWM Trait weighted by species abundances

What clustering method?

C B

D

FGR No. groups

FD Total branch length

Adapted from Petchey, O. L., & Gaston, K. J. (2006). Functional diversity: back to basics and looking forward. Ecology letters, 9(6), 741-758.

The biomass ratio hypothesis • Ecosystem properties are driven by the characteristics of dominant species. Species abundance

➡Niche complementarity

➡Biomass ratio Species rank

Garnier, et al. (2004). Plant functional markers capture ecosystem properties during secondary succession. Ecology, 85(9), 2630-2637.

Functional approach to BEF in natura • In semi-arid ecosystems Biomass ratio effects Total ecosystem C (Mg ha-1)

Total ecosystem C (Mg ha-1)

Complementarity effects

FDvar of wood-specific gravity ~ FD from multiple traits

Community weighted mean of height

➡ Dominance of biomass ratio effects Conti, G., & Díaz, S. (2013). Plant functional diversity and carbon storage–an empirical test in semi-arid forest ecosystems. Journal of Ecology, 101(1), 18-28.

Importance of rare species? Tropical forest

Functional vulnerability

Alpine tundra

Regional occupancy

• Rare species (locally and regionally) sustain unique fonctions ➡ Increase the breadth of functions provided by ecosystems, but have greater extinction risks Mouillot, D., et al. (2013). Rare species support vulnerable functions in high-diversity ecosystems. PLoS Biol, 11(5), e1001569.

A phylogenetic alternative • Rely on the idea that functional characteristics are inherited from ancestors and thus conserved. ➡ more synthetic view of ecological differences among species that drive patterns of resource use?

Garnier, E., & Navas, M. L. (2012). A trait-based approach to comparative functional plant ecology: concepts, methods and applications for agroecology. A review. Agronomy for Sustainable Development, 32(2), 365-399.

A phylogenetic alternative

Cadotte, M. W., et al. (2008). Evolutionary history and the effect of biodiversity on plant productivity. PNAS, 105(44), 17012-17017.

A phylogenetic alternative • Phylogenetic diversity is not always a good proxy of functional diversity

A first synthesis on local scale BEF

Experimental sampling or environmental filtering

Adapted from Loreau, M., et al. (2001). Biodiversity and ecosystem functioning: current knowledge and future challenges. Science, 294(5543), 804-808.

What dynamic? Environmental change? • Pulse Experimental disturbance sampling or environmental filtering => punctual • Press disturbance => long term

Species loss?

Ecosystem processes Adapted from Loreau, M., et al. (2001). Biodiversity and ecosystem functioning: current knowledge and future challenges. Science, 294(5543), 804-808.

What dynamic? Environmental change? • Pulse Experimental disturbance sampling or environmental filtering => punctual • Press disturbance => long term

Species loss?

Ecosystem processes Adapted from Loreau, M., et al. (2001). Biodiversity and ecosystem functioning: current knowledge and future challenges. Science, 294(5543), 804-808.

Biodiversity-Stability debate • Elton (1958): communities experience more violent fluctuations in population density when they are less diverse. • MacArthur (1955): Species-poor islands and artificial agricultural ecosystems are more prone to invasions by new species and pests than their continental and natural counterparts

vs. • May (1972): Communities with higher diversity tended to be less, not more, stable because higher diversity tend to undermine individual species

May’s point of view

Population size

• Models of species interactions with randomly assigned interaction strengths

Time

• Stability defined as a return to the initial state, i.e. resilience • Unrealistic interactions Review in Tilman et al. (2014) Biodiversity and Ecosystem Functioning. Annu. Rev. Ecol. Evol. Syst. 45:471–93

Biodiversity - Stability Synchrone species

Asynchrone species

• At the community level ➡ Portfolio effect: asynchrony to environmental change

1 species

➡ ~ Insurance hypothesis 2 species

8 species

Loreau, M. (2010). Linking biodiversity and ecosystems: towards a unifying ecological theory. Proc R Soc B, 365(1537), 49-60.

Biodiversity - Stability • Testing the insurance hypothesis in Cedar Creek Biomass (summed productivities)

Drought resistance

Review in Tilman et al. (2014) Biodiversity and Ecosystem Functioning. Annu. Rev. Ecol. Evol. Syst. 45:471–93

Biodiversity - Stability

• ec

Functional diversity (abundance weighted)

• Short- versus long-term experiments in Cedar Creek

➡ Interspecific complementarity accumulate over time ➡ Biodiversity loss with greater impacts than previously thoughts Reich, P. B., et al (2012). Impacts of biodiversity loss escalate through time as redundancy fades. Science, 336(6081), 589-592.

Biodiversity - Stability in space

𝛼 = No. species present locally β = difference between localities 𝛾 = No. species at the regional scale = 𝛼•β

Wang, S., & Loreau, M. (2014). Ecosystem stability in space: α, β and γ variability. Ecology letters, 17(8), 891-901.

No. Tree species

Biodiversity - Stability in space

Area (m2)

➡

Biodiversity is important not only locally but also through spatial heterogeneity

Condit, R., et al. (1996). Species-area and species-individual relationships for tropical trees: a comparison of three 50-ha plots. Journal of Ecology, 549-562. Wang, S., & Loreau, M. (2014). Ecosystem stability in space: α, β and γ variability. Ecology letters, 17(8), 891-901.

Non-random extinctions? • Simulation of extinction scenarios for aboveground C stocks • S1: extinction risk: population density / growth rate, endemicity • S2: harvesting strategies: largest populations, selection of hardwoods / largest trees species • S3: environmental change: responses to precipitation, disturbance, elevated CO2 • S4: random extinction Bunker, D. E., et al. (2005). Species loss and aboveground carbon storage in a tropical forest. Science, 310(5750), 1029-1031.

Non-random extinctions? • Selective logging recruit fast growing species => reduced C storage Simulation start

• Conversion to plantations with high wood density species would increase carbone storage capacity ➡ Ecosystem processes are determined by the mode and manner in which species are lost

Bunker, D. E., et al. (2005). Species loss and aboveground carbon storage in a tropical forest. Science, 310(5750), 1029-1031.

States of ecosystems • Alternative states and critical transition Stability landscape of a given community

High resilience : high recovery rate

Tipping point

Slowing down: signal of critical transition

Shade, A., et al. (2012). Fundamentals of microbial community resistance and resilience. Front. Microbio. 3:417 Dakos, V., et al. (2015). Resilience indicators: prospects and limitations for early warnings of regime shifts. Proc R Soc B, 370(1659), 20130263.

Toward early warning systems of critical transitions? in progress… • • • •

So far tested on models of biodiversity False positive/negative rates Need high-frequency measurements Critical slowing down indicators are not forecasting tools per se

Dakos, V., et al. (2015). Resilience indicators: prospects and limitations for early warnings of regime shifts. Proc R Soc B, 370(1659), 20130263. http://www.early-warning-signals.org/

What about other trophic levels?

Duffy, J. E., et al. (2007). The functional role of biodiversity in ecosystems: incorporating trophic complexity. Ecology letters, 10(6), 522-538.

The BEF relationship is pervasive horizontally • A meta-analysis of experiments including plants, herbivores, predators and detritivores Y = yS / ym̅ = Ymax S / (K + S) Net process Asymptotic process Halving richness

Y=Stock abundance

Y=Resources consumed

Aquatic Terrestrial

➡ Niche complementarity similar across trophic level

Cardinale, B. J., et al. (2006). Effects of biodiversity on the functioning of trophic groups and ecosystems. Nature, 443(7114), 989-992.

Vertical diversity and ecosystem functioning • BEF + food web ecology: adding interactions of species across trophic levels. • Food web ecology relies on graph theory

➡ Network topology features

Multi-trophic BEF early hypotheses • Horizontal diversity effects on other trophic levels: • Top-down control: effects of diversity stronger at higher trophic levels: higher extinction risks

Cardinale, B. J., et al. (2009). Towards a food web perspective on biodiversity and ecosystem functioning. Biodiversity and human impacts, 105-120.

Multi-trophic BEF early hypotheses • Horizontal diversity effects on other trophic levels: • Bottom up control: Increasing • Top-down control: effects of diversity of resources reduces the diversity stronger at higher trophic strength of top-down control by levels: higher extinction risks consumers (edibility, dilution, ennemies, balanced diet)

Cardinale, B. J., et al. (2009). Towards a food web perspective on biodiversity and ecosystem functioning. Biodiversity and human impacts, 105-120.

Multi-trophic BEF early hypotheses • Diversity effects across trophic levels • Top-down effects of consumer diversity oppose the bottom-up effects of resource diversity • Diversity effects by any focal trophic level
 are reduced in the presence of higher trophic levels

• Trophic cascades are weaker in diverse communities

Cardinale, B. J., et al. (2009). Towards a food web perspective on biodiversity and ecosystem functioning. Biodiversity and human impacts, 105-120.

Food-web constraints on BEF? • Nutrient-limited and heterogeneous environment with plants, herbivores that are specialists or generalists Specialists FWC1

H1

… Hn-1

Hn

H1 … Hn-1

Hn

P1

… Pn-1

Pn

P1 … Pn-1

Pn

Generalists FW3

➡ Depends on dietary generalism, trade-offs between competition and resistance to predation, intraguild predation, and migration Thebault, E., & Loreau, M. (2003). Food-web constraints on biodiversity–ecosystem functioning relationships. PNAS, 100(25), 14949-14954.

Food-web constraints on BEF? z-scores Level manipulated Plants Herbivores Mycorhiza Decomposers Multitrophic

• Biodiversity always enhances ecosystem functions • Producer diversity positively influences higher trophic levels • Greater stability for certain pressures only Balvanera, P., et al. (2006). Quantifying the evidence for biodiversity effects on ecosystem functioning and services. Ecology letters, 9(10), 1146-1156.

Overhunting effects in tropical forests

Large-bodied dispersers non-endangered

Endangered

Carbon deficit (Mg/ha) after defaunation simulation

Bello, C., et al (2015). Defaunation affects carbon storage in tropical forests. Science advances, 1(11), e1501105.

What about the belowground?

Direct interactions Mutualistic (e.g. Mycorrhizae) Pathogene infection Root feeding Competition for ressources

Aboveground biota

CO2, N2

Green web => producer-based

Organic Matter Input

Plant uptake

C Immobilization

Belowground “black box”

Fragmentation/ mineralization

Nutrient pool C/N Mobilisation

Brown web Indirect interactions

=> detritus-based

C leaching

Bardgett, R. D., & van der Putten, W. H. (2014). Belowground biodiversity and ecosystem functioning. Nature, 515(7528), 505-511.

What about the belowground?

Bardgett, R. D., & van der Putten, W. H. (2014). Belowground biodiversity and ecosystem functioning. Nature, 515(7528), 505-511.

What about the belowground? Temperate grassland

1 m2

Meso/Maiofauna: Nematodes: 1,000’s individuals 10,000 individuals 100’s of species 100’s of species

Fungi: 50 km of hyphae 100’s of species Plants: 100g of roots 10’s of species Protozoa: 100,000 cells 100’s of species

*you are here

Archaea: 10 millions cells 100’s of “species”

10,000’s of “species”, mostly microscopic, largely unknown (>95%)

Bacteria: 100 billions cells 10,000’s of “species”

➡ Functional redundancy?

Bardgett, R. D., & van der Putten, W. H. (2014). Belowground biodiversity and ecosystem functioning. Nature, 515(7528), 505-511.

Toward an integrated view of above and belowground food webs

Scherber, C., et al. (2010). Bottom-up effects of plant diversity on multitrophic interactions in a biodiversity experiment. Nature, 468(7323), 553-556.

Extinction risks of the soil biota? • Global warming: •

Change of body size distribution

•

Top-down effects: lower levels, more omnivory

•

Variety of responses in terms of stability

Brose, U., et al. (2012). Climate change in size-structured ecosystems. Phil. Trans. R. Soc. B, 367: 2903–2912

One more layer? Environmental change? • Pulse disturbance => punctual • Press disturbance => long term

Species loss?

host performance? Ecosystem processes?

To sum up • Biodiversity loss reduces the efficiency by which ecological communities capture resources, produce biomass, decompose and recycle biologically essential nutrients. • Biodiversity increases the stability of ecosystem functions through time. • BEF relationship is nonlinear and saturating, such that change accelerates as biodiversity loss increases. • Diverse communities are more productive because they contain key species with large influence on productivity, and differences in functional traits among organisms increase total resource capture. • Loss of diversity across trophic levels has the potential to influence ecosystem functions more strongly than diversity loss within trophic levels. • Functional traits of organisms have large impacts on the magnitude of ecosystem functions => wide range of plausible impacts of extinction on ecosystem function. Cardinale, B. J., et al. (2012). Biodiversity loss and its impact on humanity. Nature, 486(7401), 59-67.

What’s next?

Cardinale, B. J., et al. (2012). Biodiversity loss and its impact on humanity. Nature, 486(7401), 59-67.

What’s next?

Cardinale, B. J., et al. (2012). Biodiversity loss and its impact on humanity. Nature, 486(7401), 59-67.

Thx