Abstract
The role of niche partitioning in structuring species‐rich soil animal communities has been debated for decades and generated the “enigma of soil animal diversity.” More recently, resource‐based niche partitioning has been hypothesized to play a very limited role in the assembly of soil animal communities. To test this hypothesis, we applied a novel combination of stable isotopes and null models of species co‐occurrence to quantify the extent of resource niche partitioning on a diverse oribatid mite community sampled from mature oak woodland.We asked whether species aggregate or segregate spatially and how these patterns correlated with the abundance of estimated trophic guilds. We also estimated the effects of environmental variables on community structure.All measured environmental variables accounted for 12% of variance in community structure, including 8% of pure spatial structure unrelated to measured environmental factors and 2% of pure environmental variance unrelated to spatial variation. Co‐occurrence analysis revealed 10 pairs of species that aggregated and six pairs of species that were spatially segregated. Values of δ15N indicated that five out of the 10 pairs of aggregated species occupied the same trophic guild, while values of δ13C indicated that species in these five pairs consumed resources of different quality, supporting a significant role of resource‐based niche partitioning. Also, one of the five pairs of segregated species occupied the same trophic guild but had overlapping δ13C values suggesting that these species do not co‐occur locally and thus minimize competition for shared resources.Partitioning of resources plays an underestimated role in soil microarthropod communities and different local communities consisted of the same trophic guilds with species identity changing from place to place. The sum of resource partitioning, multi‐trophic interactions, and microscale environmental variability in the environment is a viable solution to the enigma of soil animal diversity.
Highlights
Temperate forest soils support a vast diversity of soil fauna spanning many taxa
Resource‐based niche partitioning has been hypothesized to play a very limited role in the assembly of soil animal communities. To test this hypoth‐ esis, we applied a novel combination of stable isotopes and null models of species co‐occurrence to quantify the extent of resource niche partitioning on a diverse oribatid mite community sampled from mature oak woodland
Partitioning of resources plays an underestimated role in soil microarthropod communities and different local communities consisted of the same trophic guilds with species identity changing from place to place
Summary
Temperate forest soils support a vast diversity of soil fauna spanning many taxa. Together with microbes, this diversity of fauna forms complex food webs, which in turn underpin much of terrestrial ecosystem functioning. Based on the assumption of a δ15N enrich‐ ment of approximately 3.4‰ per trophic guild (Minagawa & Wada, 1984; Post, 2002), on a baseline value of −3.14‰ and based on the morphology of oribatid species feeding mouth parts (chelicera) as a guide (Wallwork, 1958; see: Table S2 for chelicera), the meas‐ ured δ15N values suggested four trophic guilds that were identifiable in the present study (Figure 3) and were defined as follows: (a) phy‐ tophagous species: from −8.39‰ (O. tectus) to −5.03‰ (Carabodes areolatus), (b) primary decomposers: from −4.18‰ (Platynothrus pelti‐ fer) to −0.94‰ (S. magnus), (c) secondary decomposers: from −0.35‰ (Liebstadia similis) to 1.24‰ (C. peritus), and (d) predatory: from 2.57‰ (Suctobelbella spp.) to 4.78‰ (Q. monstruosa). Co‐occurrence data for significant species pairs were combined with their respective isotopic
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