Abstract
In semiarid ecosystems, decomposers are active during numerous short periods following rainfall events, and most inactive in the intervening dry periods. Many studies concern season-long dynamics of decomposer populations, but less is known of the short-term dynamics during wet periods. These short-term dynamics may provide the key to understanding interactions between microbes and fauna.
The dynamics of populations in the detrital food web were followed after wetting large intact soil cores that had been removed from native shortgrass steppe, winter wheat, and fallow plots. The cores were sampled over a ten day period for bacteria, fungi, protozoa, and various functional groups of microarthropods and nematodes. The native sod had appreciably greater biomass of fungi, nematodes and microarthropods than did the cultivated plots, but there was no difference in bacteria or protozoans. The observed dynamics after wetting were different in two experiments which differed in temperature, soil water level, and the initial sizes of the populations. These results were interpreted in relation to a model of the structure of the detrital food web, and estimates were made of the rates of trophic transfers in the web. Consumption by protozoa was great enough for them to account for bacterial turnover, but consumption by fungivorous nematodes and microarthropods appeared to be too small to account for fungal turnover.
Progress in understanding the dynamics of detrital food webs requires a better definition of the functional groups of soil organisms, their resources, predators and population parameters, and the effects of soil structure and water content on trophic relationships.
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Hunt, H.W., Elliott, E.T. & Walter, D.E. Inferring trophic transfers from pulse-dynamics in detrital food webs. Plant Soil 115, 247–259 (1989). https://doi.org/10.1007/BF02202593
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DOI: https://doi.org/10.1007/BF02202593