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Abstract Predators can alter the movement of nutrients through ecosystems by depositing waste products following predation. Whilst the benefits of predator waste for large predators (e.g. bears) or dense accumulations of predators (e.g. seabirds on islands) seem clear, less is known about whether smaller, solitary predators can have measurable effects on local ecosystem processes.In separate experiments with web‐building and wandering spiders, we tested if the presence of predators affected soil nutrient content, soil respiration, soil microbial communities, and plant growth.In the first experiment with black widow spiders, total nitrogen and nitrate were not affected by spider presence, but ammonia and phosphorus were higher from soil under the edge of the spider web than soil away from the spider. Soil respiration and plant growth were both higher in soil collected from under the spider retreat compared with soil collected away from the spider web.In a second experiment with wolf spiders, we tested for interactions between spiders and soil microbial communities. There were positive effects of wolf spider presence on all soil nutrients and there were interactions between spiders and soil type (i.e. field‐collected versus autoclaved) for total carbon, total nitrogen, nitrate, and pH. Spider presence and soil type also affected soil respiration and spider presence had a large effect on the composition of the microbial community of the soil. There were also positive effects of wolf spider presence on plant biomass and plant height, with a significant interaction between spiders and soil type for plant height.Overall, our results show that two spiders with different life histories (i.e. web‐building and wandering) both have significant positive effects on plant growth through the deposition of their waste products. These effects may occur through the direct deposition of nutrients and changes in soil microbial communities. Although, further work is needed to resolve these interactions. Read the freePlain Language Summaryfor this article on the Journal blog.
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Soil microbial legacies influence freeze–thaw responses of soil
Abstract Warmer winters with less snowfall are increasing the frequency of soil freeze–thaw cycles across temperate regions. Soil microbial responses to freeze–thaw cycles vary and some of this variation may be explained by microbial conditioning to prior winter conditions, yet such linkages remain largely unexplored. We investigated how differences in temperature history influenced microbial community composition and activity in response to freeze–thaw cycles.We collected soil microbial communities that developed under colder (high elevation) and warmer (low elevation) temperature regimes in spruce‐fir forests, then added each of these soil microbial communities to a sterile bulk‐soil in a laboratory microcosm experiment. The inoculated high‐elevation cold and low‐elevation warm microcosms were subjected to diurnal freeze–thaw cycles or constant above‐freezing temperature for 9 days. Then, all microcosms were subjected to a 7‐day above‐freezing recovery period.Overall, we found that the high‐elevation cold community had, relative to the low‐elevation warm community, a smaller reduction in microbial respiration (CO2flux) during freeze–thaw cycles. Further, the high‐elevation cold community, on average, experienced lower freeze–thaw‐induced bacterial mortality than the warm community and may have partly acclimated to freeze–thaw cycles via increased lipid membrane fluidity. Respiration of both microbial communities quickly recovered following the end of the freeze–thaw treatment period and there were no changes in soil extractable carbon or nitrogen.Our results provide evidence that past soil temperature conditions may influence the responses of soil microbial communities to freeze–thaw cycles. The microbial community that developed under a colder temperature regime was more tolerant of freeze–thaw cycles than the community that developed under a warmer temperature regime, although both communities displayed some level of resilience. Taken together, our data suggest that microbial communities conditioned to less extreme winter soil temperatures may be most vulnerable to rapid changes in freeze–thaw regimes as winters warm, but they also may be able to quickly recover if mortality is low. Read the freePlain Language Summaryfor this article on the Journal blog.
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- Award ID(s):
- 1920908
- PAR ID:
- 10542322
- Publisher / Repository:
- Open Access
- Date Published:
- Journal Name:
- Functional Ecology
- Volume:
- 37
- Issue:
- 4
- ISSN:
- 0269-8463
- Page Range / eLocation ID:
- 1055 to 1066
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1111/1365-2435.14273
