Trophic position of microbivorous and predatory soil nematodes in a boreal forest as indicated by stable isotope analysis

Kudrin, Alexey A.; Tsurikov, Sergey M.; Tiunov, Alexei V.

doi:10.1016/j.soilbio.2015.03.017

Cited by 51 publications

(35 citation statements)

References 79 publications

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“…Our estimations of nematode mass, in general and in particular for some distinctive taxa (e.g., the extremely large Longidorus sp. ), are similar to previously reported data (Verschoor et al., ; Vonk, Breure, & Mulder, ; Zhao et al., ), but lower than those of a database widely used to estimate nematode size in lieu of direct measurements (http://nemaplex.ucdavis.edu/Ecology/nematode_weights.htm, for example Guan et al., ; Kudrin, Tsurikov, & Tiunov, ). Besides potential biases of different extraction methods, the likely explanation is that, while the database represents only full‐grown adults, our study and those referred above also measured juveniles.…”

Section: Discussionsupporting

confidence: 90%

Grazing and resource availability control soil nematode body size and abundance–mass relationship in semi‐arid grassland

Andriuzzi

Wall

2018

Journal of Animal Ecology

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Body size is a central functional trait in ecological communities. Despite recognition of the importance of above ground-below ground interactions, effects of above-ground herbivores on size and abundance-size relationships in soil fauna are almost uncharted. Depending on climate and soil properties, herbivores may increase basal resources of soil food webs, or reduce pore space, mechanisms expected to have contrasting effects on soil animal body size. We investigated how body size and shape of soil nematodes responded to mammalian grazers in three semi-arid grassland sites, along a gradient of soil texture and organic matter (OM) in a long-term herbivore removal study. We analysed nematode mass, length, diameter, body size distribution and biomass distribution. We formulated two mechanistic hypotheses to assess whether resource availability or pore space was the dominant abiotic control and modulated the effects of grazing. In ungrazed soils, average and maximum nematode size, as well as abundance and biomass of large nematodes, were greater in the high-OM than in the low-OM soil, and intermediate in the medium-OM soil. Grazing promoted larger sizes in the low-OM soil, where it had been shown to increase OM and microbial biomass, and led to more homogeneous average size and body size distribution across sites. The results support the hypothesis that nematode size was controlled by basal resource availability rather than by pore space. However, body shape might have been constrained by small pores in the fine-texture, high-OM soil, where nematodes were more elongated. Grazing may facilitate larger sizes in soil nematode communities by boosting basal resources where these are limiting, with important implications for estimations of nematode biomass and contribution to carbon and nutrient cycling. These findings contribute to the insofar-limited mechanistic understanding of how herbivores can shape functional traits of soil fauna and demonstrate that animals at one trophic level may control patterns in body size and abundance-size relationships in other trophic levels without a direct predator prey or competitive linkage between them.

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Section: Discussionsupporting

confidence: 90%

Grazing and resource availability control soil nematode body size and abundance–mass relationship in semi‐arid grassland

Andriuzzi

Wall

2018

Journal of Animal Ecology

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“…To partly overcome the lack of experimental data, organisms with well‐known trophic ecology could be used as ‘reference trophic species’. For instance, certain species of earthworms or termites can be sampled and their stable isotope compositions used for assessing the trophic position of other species in the community (Kudrin, Tsurikov & Tiunov, ; Tiunov et al ., ). Further, Potapov & Tiunov () estimated fungivory of Collembola by comparing their δ 13 C and δ 15 N values with those of mycoheterotrophic plants known to be trophically linked to mycorrhizal or saprotrophic fungi.…”

Section: Reconstructing Trophic Linksmentioning

confidence: 97%

“…To partly overcome the lack of experimental data, organisms with well-known trophic ecology could be used as 'reference trophic species'. For instance, certain species of earthworms or termites can be sampled and their stable isotope compositions used for assessing the trophic position of other species in the community (Kudrin, Tsurikov & Tiunov, 2015;Tiunov et al, 2015). Further, Fig.…”

Section: Reconstructing Trophic Linksmentioning

confidence: 99%

Uncovering trophic positions and food resources of soil animals using bulk natural stable isotope composition

2018

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Despite the major importance of soil biota in nutrient and energy fluxes, interactions in soil food webs are poorly understood. Here we provide an overview of recent advances in uncovering the trophic structure of soil food webs using natural variations in stable isotope ratios. We discuss approaches of application, normalization and interpretation of stable isotope ratios along with methodological pitfalls. Analysis of published data from temperate forest ecosystems is used to outline emerging concepts and perspectives in soil food web research. In contrast to aboveground and aquatic food webs, trophic fractionation at the basal level of detrital food webs is large for carbon and small for nitrogen stable isotopes. Virtually all soil animals are enriched in C as compared to plant litter. This 'detrital shift' likely reflects preferential uptake of C-enriched microbial biomass and underlines the importance of microorganisms, in contrast to dead plant material, as a major food resource for the soil animal community. Soil organic matter is enriched in N and C relative to leaf litter. Decomposers inhabiting mineral soil layers therefore might be enriched in N resulting in overlap in isotope ratios between soil-dwelling detritivores and litter-dwelling predators. By contrast, C content varies little between detritivores in upper litter and in mineral soil, suggesting that they rely on similar basal resources, i.e. little decomposed organic matter. Comparing vertical isotope gradients in animals and in basal resources can be a valuable tool to assess trophic interactions and dynamics of organic matter in soil. As indicated by stable isotope composition, direct feeding on living plant material as well as on mycorrhizal fungi is likely rare among soil invertebrates. Plant carbon is taken up predominantly by saprotrophic microorganisms and channelled to higher trophic levels of the soil food web. However, feeding on photoautotrophic microorganisms and non-vascular plants may play an important role in fuelling soil food webs. The trophic niche of most high-rank animal taxa spans at least two trophic levels, implying the use of a wide range of resources. Therefore, to identify trophic species and links in food webs, low-rank taxonomic identification is required. Despite overlap in feeding strategies, stable isotope composition of the high-rank taxonomic groups reflects differences in trophic level and in the use of basal resources. Different taxonomic groups of predators and decomposers are likely linked to different pools of organic matter in soil, suggesting different functional roles and indicating that trophic niches in soil animal communities are phylogenetically structured. During last two decades studies using stable isotope analysis have elucidated the trophic structure of soil communities, clarified basal food resources of the soil food web and revealed links between above- and belowground ecosystem compartments. Extending the use of stable isotope analysis to a wider range of soil-dwelling organisms, including mi...

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“…This technique has been used to study plant-C utilization by microbial communities in soils by examining 13 C incorporation into microbial phospholipid fatty acids (PLFAs; e.g., Denef et al, 2009;Rubino et al, 2010;Kohl et al, 2015;Soong et al, 2016). Also, natural abundances of 13 C and 15 N have been useful for studying structures of soil faunal communities (e.g., collembolans, earthworms, enchytraeids, arthropods, gastropods, and nematodes; Chahartaghi et al, 2005;Albers et al, 2006;Goncharov et al, 2014;Crotty et al, 2014;Kudrin et al, 2015). Furthermore, C flow though soil faunal trophic groups can be traced and quantified using 13 C in labeling experiments (Albers et al, 2006;Pollierer et al, 2007;Elfstrand et al, 2008;Ostle et al, 2007;D'Annibale et al, 2015;Gilbert et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Fire affects root decomposition, soil food web structure, and carbon flow in tallgrass prairie

Shaw

Denef

Tomasel

et al. 2016

SOIL

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Abstract. Root litter decomposition is a major component of carbon (C) cycling in grasslands, where it provides energy and nutrients for soil microbes and fauna. This is especially important in grasslands where fire is common and removes aboveground litter accumulation. In this study, we investigated whether fire affects root decomposition and C flow through the belowground food web. In a greenhouse experiment, we applied 13 C-enriched big bluestem (Andropogon gerardii) root litter to intact tallgrass prairie soil cores collected from annually burned (AB) and infrequently burned (IB) treatments at the Konza Prairie Long Term Ecological Research (LTER) site. Incorporation of 13 C into microbial phospholipid fatty acids and nematode trophic groups was measured on six occasions during a 180-day decomposition study to determine how C was translocated through the soil food web. Results showed significantly different soil communities between treatments and higher microbial abundance for IB. Root decomposition occurred rapidly and was significantly greater for AB. Microbes and their nematode consumers immediately assimilated root litter C in both treatments. Root litter C was preferentially incorporated in a few groups of microbes and nematodes, but depended on burn treatment: fungi, Gram-negative bacteria, Gram-positive bacteria, and fungivore nematodes for AB and only omnivore nematodes for IB. The overall microbial pool of root-litter-derived C significantly increased over time but was not significantly different between burn treatments. The nematode pool of root-litter-derived C also significantly increased over time, and was significantly higher for the AB treatment at 35 and 90 days after litter addition. In conclusion, the C flow from root litter to microbes to nematodes is not only measurable but also significant, indicating that higher nematode trophic levels are critical components of C flow during root decomposition, which, in turn, is significantly affected by fire. Not only does fire affect the soil community and root decomposition, but the lower microbial abundance, greater root turnover, and the increased incorporation of root litter C by microbes and nematodes for AB suggests that annual burning increases root-litter-derived C flow through the soil food web of the tallgrass prairie.

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Trophic position of microbivorous and predatory soil nematodes in a boreal forest as indicated by stable isotope analysis

Cited by 51 publications

References 79 publications

Grazing and resource availability control soil nematode body size and abundance–mass relationship in semi‐arid grassland

Grazing and resource availability control soil nematode body size and abundance–mass relationship in semi‐arid grassland

Uncovering trophic positions and food resources of soil animals using bulk natural stable isotope composition

Fire affects root decomposition, soil food web structure, and carbon flow in tallgrass prairie

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