Browsing by Subject "beetles"

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    A brown-world cascade in the dung decomposer food web of an alpine meadow: effects of predator interactions and warming
    (2011) Wu, Xinwei; Duffy, J. Emmett; Reich, Peter B; Sun, Shucun
    Top-down control has been extensively documented in food webs based on living plants, where predator limitation of herbivores can cascade to facilitate plant growth (the green-world hypothesis), particularly in grasslands and aquatic systems. Yet the ecosystem role of predators in detrital food webs is less explored, as is the potential effect of climate warming on detritus-based communities. We here show that predators have a “brown-world” role in decomposer communities via a cascading top-down control on plant growth, based on the results of an experiment that factorially manipulated presence and size of two predator species as well as temperature (warmed vs. unwarmed). The inclusion of predatory beetles significantly decreased abundance of coprophagous beetles and thus the rate of dung decomposition and productivity of plants growing surrounding the dung. Moreover, the magnitude of these decreases differed between predator species and, for dung loss, was temperature dependent. At ambient temperature, the larger predators tended to more strongly influence the dung loss rate than did the smaller predators; when both predators were present, the dung loss rate was higher relative to the treatments with the smaller predators but comparable to those with the larger ones, suggesting an antagonistic effect of predator interaction. However, warming substantially reduced dung decomposition rates and eliminated the effects of predation on dung decomposition. Although warming substantially decreased dung loss rates, warming only modestly reduced primary productivity. Consistent with these results, a second experiment exploring the influence of the two predator species and warming on dung loss over time revealed that predatory beetles significantly decreased the abundance of coprophagous beetles, which was positively correlated with dung loss rates. Moreover, experimental warming decreased the water content of dung and hence the survival of coprophagous beetles. These results confirm that the “brown-world” effect of predator beetles was due to cascading top-down control through coprophagous beetles to nutrient cycling and primary productivity. Our results also highlight potentially counterintuitive effects of climate warming. For example, global warming might significantly decrease animal-mediated decomposition of organic matter and recycling of nutrients in a future warmed world.
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    Light, earthworms, and soil resources as predictors of diversity of 10 soil invertebrate groups across monocultures of 14 tree species
    (Elsevier, 2016) Mueller, Kevin E; Eisenhauer, Nico; Reich, Peter B; Hobbie, Sarah E; Chadwick, Oliver A; Chorover, Jon; Dobies, Tomasz; Hale, Cynthia M; Jagodziński, Andrzej M; Kałucka, Izabela; Kasprowicz, Marek; Kieliszewska-Rokicka, Barbara; Modrzyński, Jerzy; Rożen, Anna; Skorupski, Maciej; Sobczyk, Łukasz; Stasińska, Małgorzata; Trocha, Lidia K.; Weiner, January; Wierzbicka, Anna; Oleksyn, Jacek
    Management of biodiversity and ecosystem services requires a better understanding of the factors that influence soil biodiversity. We characterized the species (or genera) richness of 10 taxonomic groups of invertebrate soil animals in replicated monocultures of 14 temperate tree species. The focal invertebrate groups ranged from microfauna to macrofauna: Lumbricidae, Nematoda, Oribatida, Gamasida, Opilionida, Araneida, Collembola, Formicidae, Carabidae, and Staphylinidae. Measurement of invertebrate richness and ancillary variables occurred ∼34 years after the monocultures were planted. The richness within each taxonomic group was largely independent of richness of other groups; therefore a broad understanding of soil invertebrate diversity requires analyses that are integrated across many taxa. Using a regression-based approach and ∼125 factors related to the abundance and diversity of resources, we identified a subset of predictors that were correlated with the richness of each invertebrate group and richness integrated across 9 of the groups (excluding earthworms). At least 50% of the variability in integrated richness and richness of each invertebrate group was explained by six or fewer predictors. The key predictors of soil invertebrate richness were light availability in the understory, the abundance of an epigeic earthworm species, the amount of phosphorus, nitrogen, and calcium in soil, soil acidity, and the diversity or mass of fungi, plant litter, and roots. The results are consistent with the hypothesis that resource abundance and diversity strongly regulate soil biodiversity, with increases in resources (up to a point) likely to increase the total diversity of soil invertebrates. However, the relationships between various resources and soil invertebrate diversity were taxon-specific. Similarly, diversity of all 10 invertebrate taxa was not high beneath any of the 14 tree species. Thus, changes to tree species composition and resource availability in temperate forests will likely increase the richness of some soil invertebrates while decreasing the richness of others.