Soil as a Support of Biodiversity and Functions - Soil Carbon: Science, Management and Policy for Multiple Benefits - page 141

11 Soil as a Support of Biodiversity
and Functions

Pierre-Alain Maron* and Philippe Lemanceau

Abstract
The soil is a major reservoir of biological diversity on our planet. It also shelters numerous biological
and ecological processes and therefore contributes to the production of a considerable number of eco-
system services. Among the ecological, social and economic services identified, the role of soil as a
reservoir of diversity has now been well established, along with its role in nutrient cycling, supporting
primary productivity, pollution removal and storing carbon.
Since the development of industrialization, urbanization and agriculture, soils have been sub-
jected to numerous variations in environmental conditions, which have resulted in modifications of
the diversity of the indigenous microbial communities. As a consequence, the functional significance
of these modifications of biodiversity, in terms of the capacity of ecosystems to maintain the functions
and services on which humanity depends, is now of pivotal importance. The concerns emanating from
the scientific community have been reiterated in the Millennium Ecosystem Assessment (MEA, 2005)
published by the policy makers. This strategic document underlines the need to consider biodiversity
as an essential component of ecosystems, not only because of its involvement in providing services
essential to the well-being of human societies but also because of its intrinsic value in terms of a nat-
ural patrimony that needs to be preserved. This objective cannot be raised without the improvement
of our ability to predict the effects of environmental changes on soil biodiversity, ecosystem function-
ing and the associated services; this requires a better quantification of soil biodiversity at different
temporal and spatial scales, and its translation into biological functioning. Major advances in molecu-
lar biology since the mid-1990s have allowed the development of techniques to investigate and resolve
the diversity of soil microbial communities (Maron et al ., 2007).
This chapter describes present and ongoing conceptual and methodological strategies employed to
assess and understand better the distribution and evolution of soil microbial diversity at different spatial and
temporal scales. It also presents actual knowledge about the link between soil microbial diversity and soil
processes, with emphasis on C and N cycling, which are determinant for many of the ecosystem services.

Introduction

estimated amount of 2000-3500 Gt of soil or-
ganic matter (SOM) (twice more than in the
atmosphere). Thus, C is a major soil compo-
nent, controlling its ability to deliver many

Soil represents one of the most important
stocks of carbon (C) of the biosphere, with an