ena-STUDY-Tartu university-03-10-2019-07:55:47:658-269
Woody encroachment in grassland elicits complex changes in the functional structure of above- and belowground biota
Woody encroachment affects dry grasslands globally. To predict changes in biodiversity and ecosystem processes, it is important to understand how this process affects the functional composition of grassland organism groups. In this context, seminatural wooded meadows represent a form of experimental manipulation – where open grassland and woody patches co-occur in homogeneous abiotic conditions due to human management decisions – which provides an opportunity to address the effect of woody plant encroachment on vegetation and soil biota. We used DNA metabarcoding to address variation in plant, soil fungal and soil animal communities in parallel. We also addressed functional groups of fungi – pathotrophs, saprotrophs, arbuscular mycorrhizal (AM), ectomycorrhizal (EcM), endophytic (mostly orchid mycorrhizal), and other symbiotrophic fungi – and of soil animals – fungivores, bacterivores, litter feeders, root feeders, macro plant feeders, algal/lichen feeders, predators and parasites. There was co-variation between communities detected from aboveground vegetation plots and metabarcoding of soil DNA, in terms of estimated richness and compositional patterns. Differences between open and wooded patches were most pronounced among plants and symbiotic fungi, whereas soil animals exhibited less marked differences. For most organisms, mean sample richness, as well as total richness per habitat type, were higher in open than wooded patches, but ectomycorrhizal (EcM) fungi exhibited the opposite pattern. The functional structure of the soil biotic community, as characterized by the proportion of DNA sequences attributed to different functional groups, differed significantly between open and wooded grassland patches, with symbiotic fungi (AM, EcM and other symbiotrophic (mostly orchid mycorrhizal) fungi) contributing most to the difference. This study supports the notion that a soil DNA based metabarcoding approach can provide insights into the diversity and composition of multiple taxonomic groups in natural ecosystems. It also provides a first demonstration of the complex changes to the functional structure of the biotic community that accompany woody encroachment in grasslands.
Woody encroachment affects dry grasslands globally. To predict changes in biodiversity and ecosystem processes, it is important to understand how this process affects the functional composition of grassland organism groups. In this context, seminatural wooded meadows represent a form of experimental manipulation – where open grassland and woody patches co-occur in homogeneous abiotic conditions due to human management decisions – which provides an opportunity to address the effect of woody plant encroachment on vegetation and soil biota. We used DNA metabarcoding to address variation in plant, soil fungal and soil animal communities in parallel. We also addressed functional groups of fungi – pathotrophs, saprotrophs, arbuscular mycorrhizal (AM), ectomycorrhizal (EcM), endophytic (mostly orchid mycorrhizal), and other symbiotrophic fungi – and of soil animals – fungivores, bacterivores, litter feeders, root feeders, macro plant feeders, algal/lichen feeders, predators and parasites. There was co-variation between communities detected from aboveground vegetation plots and metabarcoding of soil DNA, in terms of estimated richness and compositional patterns. Differences between open and wooded patches were most pronounced among plants and symbiotic fungi, whereas soil animals exhibited less marked differences. For most organisms, mean sample richness, as well as total richness per habitat type, were higher in open than wooded patches, but ectomycorrhizal (EcM) fungi exhibited the opposite pattern. The functional structure of the soil biotic community, as characterized by the proportion of DNA sequences attributed to different functional groups, differed significantly between open and wooded grassland patches, with symbiotic fungi (AM, EcM and other symbiotrophic (mostly orchid mycorrhizal) fungi) contributing most to the difference. This study supports the notion that a soil DNA based metabarcoding approach can provide insights into the diversity and composition of multiple taxonomic groups in natural ecosystems. It also provides a first demonstration of the complex changes to the functional structure of the biotic community that accompany woody encroachment in grasslands.