The Global Challenge for Soil Carbon - Soil Carbon: Science, Management and Policy for Multiple Benefits - page 4

distribution that allows both water storage in
small throats and pores and free drainage of
water and ingress of atmospheric O 2 , to sup-
port root and microbial respiration, through
connected networks of larger pores.
Soil organic matter and soil carbon are
thus central to all of the underpinning phys-
ical, chemical and biological processes of
soil functions. At the landscape scale, the re-
sulting transformations and flows of material,
energy and genetic information are delivered
as ecosystem services that provide enormous
benefits for humans ( Fig. 1.1 ). This view of
the environment is embodied in the concept
of soil as natural capital that provides a
means of production for the ongoing supply
of beneficial goods and services (Robinson
et al ., 2013). Indeed, Robinson et al . (2013)
noted soil carbon, along with soil organisms,
embodied biogeochemical energy and the
structural organization of soil as the key
components of this natural capital. This
view is broadly held through the following
chapters of this volume and inherently intro-
duces an anthropocentric view of natural

processes that describes these in terms of
economic services with an instrumental value
for human well-being. The latter is not ana-
lysed explicitly, but this departs from a
broader biocentric perspective of the intrin-
sic value of Earth's environment and the on-
going processes that it supports.
Drawing on the concepts of ecosystem
services within the Millennium Ecosystem
Assessment defines the following services
arising from soil functions (MEA, 2005; Black
et al ., 2008; Robinson et al ., 2013).

1. Supporting services are the cycling of
nutrients, the retention and release of water,
the formation of soil, provision of habitat
for biodiversity, the exchange of gases with
the atmosphere and the degradation of plant
and other complex materials.
2. Regulating services for climate, stream
and groundwater flow, water and air qual-
ity and environmental hazards are: the se-
questration of carbon from the atmosphere,
emission of greenhouse gases, the filtration
and purification of water, attenuation of

Water filtration
Contaminant attenuation
Carbon storage
Nutrient
transformation
Aerosol transport
Gas exchange

Land surface

Soil parent
material

Soil layer
Mobile
regolith

Food, fibre and fuel
Genetic stock

Mobile
regolith

Water
table
Bedrock

Soil

Geological
storage of waste

Bedrock -
mineral
nutrient source

Gene pool
Biological habitat

Lakes and
streams

Soil

Baseflow

Physical scaffold for landscapes

Water storage and transmission
Contaminant attenuation

Aquifer

Scaffold and transmission
of heat

Saprolite

Bedrock - mineral nutrient source

Fig. 1.1. Soil functions and ecosystem services are at the heart of Earth's critical zone; the thin outer layer
of the planet that supports almost all human activity. Within this hill slope diagram, the arrows illustrate
important flows of material, energy and genetic information that support ecosystem services and provide
essential benefits. These flows create a chain of impact that propagates changes in the aboveground
environment (e.g. changing climate, land use), via the soil layer, throughout the critical zone. Thus, consider-
ing decisions that affect soil requires understanding consequences along the entire chain of impact; and
the full consideration of all costs and benefits whether intended or not. (From Banwart et al ., 2012.)