Trophic relationships in the soil microfood‐web: predicting the responses to a changing global environment

Abstract

In this article, we evaluate how global environmental change may affect microfood‐webs and trophic interactions in the soil, and the implications of this at the ecosystem level. First we outline how bottom‐up (resource control) and top‐down (predation‐control) forces regulate food‐web components. Food‐web components can respond either positively or negatively to shifts in NPP resulting from global change, thus creating difficulties in developing general principles about the response of soil biota to global change phenomena. We also demonstrate that top‐down effects can be important in soil food‐webs, creating negative feed‐backs which may partially counter bottom‐up effects. Secondly, we determine how soil food‐webs and the processes they regulate respond to various global change phenomena. Enhanced atmospheric CO2 levels can have two main effects on plants which are relevant for the soil food‐web, i.e. enhanced NPP (often positive) and diminished organic matter quality (with negative effects, at least in the short term). Climate change effects resulting from elevated CO2 levels may be mainly secondary through alteration of vegetation, as shown by examples. Intensification of land management is usually associated with greater disturbance, which alters soil food‐web composition and key processes; this is particularly apparent in comparisons of conventionally tilled and nontilled agroecosystems. Global change involves shifts in plant species composition and diversity, possibly affecting soil food‐webs; we interpret this in terms of theories relating biodiversity to ecosystem function. We conclude that a more detailed understanding of interactions between NPP, soil organic matter and components of the soil food‐web, as well as their regulation of biogeochemical processes and ultimately ecosystem‐level properties, is essential in better understanding long‐term aspects of global change phenomena.

Effects of experimental irrigation and drought on the composition and diversity of soil fauna in a coniferous stand

“…1997;IPCC 2001) and have major consequences for the earth's biodiversity (Hoffman & Parsons 1997;Swift et al . 1998;Wardle, Verhoef & Clarholm 1998). As soil communities are among the most species-rich components of terrestrial ecosystems, their importance to global biodiversity is substantial (Giller 1996;Adams & Wall 2000).…”

Influence of depth and sampling time on bacterial community structure in an upland grassland soil

“…In light of recent concerns regarding the impact of agriculture and climate change on biodiversity and ecosystem functioning [1,2], it is imperative to gain a more detailed understanding of the bacterial community ecology in our remaining native grasslands. However, this task is arduous due to the enormous diversity of soil bacteria, together with the complexity of factors regulating their growth and survival.…”

Bridging the gap between micro - and macro-scale perspectives on the role of microbial communities in global change ecology

“…Tillage, forest clearcutting, or urban development all physically disrupt the soil, and have been shown to alter the relative abundance of major microbial functional types (Beare 1997;Pennanen et al 1999;Wardle et al 1999;Fraterrigo et al 2006). In addition, environmental conditions altered by changing land use may impact microbial communities or alter soil trophic interactions, thus indirectly effecting changes in microbial communities (Schimel and Gulledge 1998;Wardle et al 1998;Wolters et al 2000).…”