Detritus is a central feature in marine, freshwater, and terrestrial ecosystems. Despite the ubiquity of detritus, ecologists have largely ignored its role in influencing food web structure. We used a meta‐analytic approach to ask three questions about how detritus affects food web structure in a wide variety of ecosystems. First, what is the effect strength of detritus on primary producers, detritivores, herbivores, and predators? Second, what functional role does detritus serve for consumers (energetic, habitat, or both)? Third, how does the effect of detritus on consumers vary between aquatic and terrestrial ecosystems? We found that detritus has strong positive effects on primary producers and consumers in a wide range of ecosystems types. Detritus has a positive direct effect on detritivores by providing both an energetic resource and habitat (refuge from predators). Detritus has equally strong positive effects on herbivores and predators, driven by a positive direct effect of habitat. Detritus has positive effects on consumers in both aquatic and terrestrial ecosystems with 1.7 times stronger effects in terrestrial ecosystems. These results suggest that detritus has strong effects on food‐web structure in a variety of ecosystem types. Even the portion of the food web that is linked most strongly to living plant tissue as its primary energy source is strongly positively affected.

No abstract

Selenium (Se) hyperaccumulation, when plant species accumulate upwards of 1,000 mg Se kg −1 dry weight (DW), protects plants from a variety of herbivores and pathogens. The objective of this study was to determine the effect of plant Se concentration on the rate of litter decomposition by invertebrates and microbes in a seleniferous habitat. Decomposition, Se loss, the decomposer community and soil Se concentration beneath leaf litter were compared between litter from two populations of the Se hyperaccumulator Astragalus bisulcatus (one population with 350 and the other with 550 mg Se kg −1 DW) and from the related non-accumulator species Astragalus drummondii and Medicago sativa containing 1-2 mg Se kg −1 DW using a litterbag method. High-Se litter decomposed faster than lowSe litter and supported more microbes and arthropods than low-Se leaf litter after 8 and 12 months, respectively. Soil collected from under high-Se litter had higher Se concentration than soil from beneath low-Se litter after 8 months. The higher decomposition rate and abundance of decomposers in highSe litter indicates the presence of Se-tolerant decomposers in this seleniferous habitat that may have contributed to increased decomposition rates of high-Se litter.

No abstract