Soil Ecology

by

Franciska T. De Vries, Richard D. Bardgett

• LAST REVIEWED: 23 May 2012
• LAST MODIFIED: 23 May 2012
• DOI: 10.1093/obo/9780199830060-0067

Introduction

The study of soil ecology has a long tradition. Most of this interest, until relatively recently, has been from an agricultural perspective, but now it is widely accepted that soil ecology is central to the study of terrestrial ecology. Early research in soil ecology was largely descriptive, detailing the abundance of diversity of organisms in soils of different habitats. However, interest in functional soil ecology started in the 1980s with studies of trophic interactions in soil and their importance for nutrient cycles and decomposition. Now, the topic has blossomed, with the help of new technologies that allow the study of soil organisms and their activities in situ, and there is currently widespread recognition that soil ecology is fundamental to our understanding of the functioning of terrestrial ecosystems and their response to global change. Today, the field of soil ecology is dominated by discussions on the use of new molecular tools that enable ecologists to understand what regulates patterns of diversity in soil, the functional role of soil biodiversity and plant-soil interactions, especially those that occur at the root-soil interface, and the role of soil biological communities in regulating ecosystem responses to global change, including the global carbon cycle under climate change. Many challenges still remain in soil ecology, and perhaps the most significant is the need for a stronger theoretical basis for the subject; almost all studies in this area have been carried out from an empirical perspective, and modeling approaches are still in their infancy. As a consequence, our ability to make predictions about the role of soil biological interactions and feedbacks in regulating terrestrial ecosystem processes and their response to global change remains limited.

General Overviews

It has long been known that soil organisms and their activities are central to the maintenance of soil fertility. As a result, there is a rich historical literature on the topic of soil biology in agriculture, including pioneering studies on the soil microbial biomass concept—the living component of the soil organic matter—which revolutionized the field (Jenkinson and Powlson 1976). Despite this, it is only in relatively recent years that community and ecosystem ecologists have turned their attention to the ecology of soil and its role in regulating ecosystem processes, such as decomposition, nutrient and carbon cycling, and plant community dynamics. Initial work in this area focused initially on topics such as controls on decomposition processes, including the highly influential synthesis of Swift, et al. 1979, and the role of trophic interactions in soil for processes of decomposition and nutrient cycling (Anderson, et al. 1983; Clarholm 1985), and plant nutrient acquisition and growth (Ingham, et al. 1985; Setälä and Huhta 1991). These studies laid the foundation for much subsequent work that has shown how multitrophic interactions in soil can serve as drivers of decomposition, plant nutrient acquisition and growth, and vegetation dynamics. Another key development in this area has been the growing recognition that terrestrial ecosystems consist of both aboveground and belowground subsystems, and that feedbacks between these subsystems play a crucial role in regulating community structure and ecosystem functioning (Wardle, et al. 2004). As a result, it is now widely accepted that biotic interactions between aboveground and belowground communities play a major role in regulating the response of terrestrial ecosystems to human-induced global change (Bardgett and Wardle 2010).

• Anderson, Jonathan M., Philip Ineson, and S. A. Huish. 1983. Nitrogen and cation mobilization by soil fauna feeding on leaf litter and soil organic matter from deciduous woodlands. Soil Biology and Biochemistry 15:463–467.

  DOI: 10.1016/0038-0717(83)90012-3

  This study was among the first to show how the activities of various groups of macrofauna can cause a marked increase in soil nutrient availability in forest organic matter.

• Bardgett, Richard D., and David A. Wardle. 2010. Aboveground–belowground linkages: Biotic interactions, ecosystem processes, and global change. Oxford: Oxford University Press.

  This book provides a comprehensive synthesis of recent advances in our understanding of the roles that interactions between aboveground and belowground communities play in regulating the structure and function of terrestrial ecosystems, and their responses to global change.

• Clarholm, Marianne. 1985. Interactions of bacteria, protozoa and plants leading to mineralization of soil nitrogen. Soil Biology and Biochemistry 17:181–187.

  DOI: 10.1016/0038-0717(85)90113-0

  This study established the concept of the microbial loop in soil, whereby grazing of bacteria by protozoa is necessary to make nitrogen contained in the microbial biomass available for plant uptake.

• Ingham, Russell E., J. A. Trofymow, Elaine R. Ingham, and David C. Coleman. 1985. Interactions of bacteria, fungi, and their nematode grazers: Effects on nutrient cycling and plant-growth. Ecological Monographs 55.1: 119–140.

  DOI: 10.2307/1942528

  This paper was one of the first studies to show experimentally that the feeding activities of soil animals on microbes enhance rates of nitrogen mineralization and plant nitrogen uptake.

• Jenkinson, David S., and David S. Powlson. 1976. Effects of biocidal treatments on metabolism in soil: 5. Method for measuring soil biomass. Soil Biology and Biochemistry 8:209–213.

  This paper describes a new method for measuring microbial biomass in soil: soil is fumigated with chloroform, then the chloroform is removed, the soil incubated, and carbon dioxide evolution measured.

• Setälä, Heikki, and Veikko Huhta. 1991. Soil fauna increase Betula pendula growth: Laboratory experiments with coniferous forest floor. Ecology 72.2: 665–671.

  DOI: 10.2307/2937206

  This paper describes a mesocosm experiment with sterilized and refaunated treatments, the results of which indicate that soil fauna, via enhanced nutrient mobilization and favorable changes in the structural soil properties, exert a positive influence on plant growth.

• Swift, Michael J., O. William Heal, and Jonathan M. Anderson. 1979. Decomposition in terrestrial ecosystems. Oxford: Blackwell.

  This classic book provides a comprehensive synthesis of decomposition processes and their role in ecosystems.

• Wardle, David A., Richard D. Bardgett, John N. Klironomos, Heikki Setälä, Wim H. van der Putten, and Diana H. Wall. 2004. Ecological linkages between aboveground and belowground biota. Science 304:1629–1633.

  DOI: 10.1126/science.1094875

  This paper proposes a framework for understanding how aboveground and belowground communities interact, and identifies the direct root-associated and the indirect decomposer pathways through which they operate.