Biotic interactions and trait-based ecosystem functioning in arable fields vs. field margins Valentina Sechi

Points of my talk: 1.Background 2.Objectives 3.Hypotheses 4.Experimental Design 5.Main Results 6.Preliminary Conclusions 2

Background 3 Ecosystem services are a key to value ecosystems and to promote sustainable use of natural resource Soil attributes and biotic interactions play important roles in ecological processes, ecosystem functioning and, hence, in the delivery of ecosystem services Therefore we need to understand how different organisms actually contribute to the ecosystem services QESAP project: (Quantification of Ecosystem Service for environmental Assessment and Planning)

General Objectives The main objectives of the QESAP-project are: Understanding the mechanisms underlying Ecosystem Functioning Developing a tool to quantify Ecosystem Services In particular my PhD aims to: I.Explore the main processes (biotic and abiotic) which are underpinning soil ecosystem services and assess the traits that influence ecosystem functioning II.Identify and quantify the relationship between ecological processes and ecosystem functioning 4

Objectives of the current study Investigating the belowground value of margins along arable fields with a trait-based approach Characterizing how components of the soil community respond to different management (pressures) and therefore Providing links between taxonomy, trait-based ecology, and ecosystem functioning 5

In this study we looked at the following functional traits: Ecophysiological traits: Microbial Respiration Community response traits: Abundance, Biomass, Shannon, Jaccard Functional diversity: Faunal feeding-group distribution Functional response traits: Maturity Index, Enrichment, Structure Functional effect traits: Allometric scaling Functional traits… … capture different characteristics of an organism that link to the organism’s function: determine individual responses to pressures determine the effects on ecosystem processes (effect trait). 6

Hypotheses 7 Figure from Mulder et al Adv. Ecol. Res. 46:1–88 Traits composition of soil communities in grass margins differs from that in arable fields: i)Margins are dominated by larger-sized species with lower numerical abundance ii)Change in the trophic groups composition iii)Higher biodiversity in the margins

Experimental Design: 8 Arable Field Field Margin Site: Hoekschse Waard Sampling Time: late September Design: 4 Farms x 2 Treatments (margins vs. arable) x 4 Pseudo-Replicates Criteria for the selection of the area : Conventional farms Homogeneous croplands: wheat Field margins older then 3-4 years Sampling: Fungi, Bacteria, Nematodes, Enchytraeids Collembolans, Mites, Earthworms Arable field Field margin m 20 m

Soil Parameters: 9

Soil community response traits: Ecophysiological traits: 10

11 Log B Log N Soil community response traits: Abundance and Biomass The biomass and the abundance of Nematoda and Enchytraeidae were higher in the margin Biomass of Micro-arthropoda is higher in the margin The biomass and the abundance of Lumbricidae are not significantly different between treatments

Nematodes present lower biodiversity in the margins Mites biodiversity is higher in the margins Enchytraeids biodiversity of is higher in the margins of Farm 1 and Farm 3 Earthworms and Collembola biodiversity does not differ between treatments Soil community response traits : Shannon Index 12

Shannon index and Jaccard Similarity Sites Ordinate by Shannon Index (H’) No faunal similarities across farms and treatments Enchytraeidae Nematoda AcarinaCollembola Sites Clustered by Jaccard similarity Biodiversity is not clearly enhanced in the margins but… 13

Log N Enchytraeidae Nematoda AcarinaCollembola Log M Plant feeders are more abundant (but smaller) in the margin (more evident for Collembola and Enchytraeids ). Plant feeders Predators Predatory Nematodes are bigger in the margins and predatory Mites are less abundant in the margins Functional Diversity: Faunal feeding-group distribution 14 Bacterial feeder Plant Feeder Fungal FeederSubstrate FeederPredatorOmnivoreParasite

Functional response traits: Maturity Index Margins Arable Margins Arable Margin has less disturbed and more structured community Enrichment Structure Index 15 Arable Margin

Functional effect traits: Allometric scaling… 16 Mulder et al. 2011, Oikos, 120:529–536  Allometry, in its broadest sense, describes how the characteristics of living creatures change with body size  In my study it is the scaling between traits (e.g., between body mass and numerical abundance).  The study of allometry concerns the functional mechanisms that generate scaling relationships and how the resulting scaling responds to environmental changes Intensity of treat One step back….What is allometry? 16

Slightly significant difference in the allometric scaling between margin and arable field (slope is less steep in the margin) If we look to stoichiometry, the allometric scaling is directly correlated with C, N and P (the more the nutrient(s), the less steep the slope) Arable: Slope ±0.02 Intercept 4.56±0.04 Margin: Slope ±0.02 Intercept 4.48±0.04 Functional effect traits: Allometric Scaling 17 Entire soil food-web

Allometric Scaling: micro- and meso- fauna Intercept is lower in the fields margin Slope is less steep in the field margins However… Slope Interc Slope Interc Slope Interc Slope Interc Slope Interc Slope Interc Slope Interc Slope Interc The coefficient of variation of slope-changes in the margins is almost twice as high as in the arable fields (CV = 19% vs. 10%, respectively).

Main Results: i)Traits composition of soil biota in margins differed from arable fields. In general: – ranked organisms (as classes or taxocenes) are more abundant and have higher biomass in the margins. ii)There is a shift in the feeding group composition between treatments. – Plant feeders (and in some cases fungal feeders) are more abundant in the margins. iii)Despite changes in allometric scaling across farms, there is a significant difference between treatments. iv)Belowground biodiversity responds slowly to the changes in land management or soil nutrient composition. 19

Preliminary conclusion and perspective 20 Functional traits reflect environmental pressure and therefore are the suitable tool to quantify habitat–ecosystem and community responses Further study is needed to i)improve the understanding of the dynamics occurring in the ecosystem under different environmental pressure ii)find a direct link between functional traits and ecosystem functioning

Thank you for your attention! Valentina Sechi 21

Supplementary slide: STATISTICS 22