Geoscience Reference
In-Depth Information
different land types (e.g. woodland, pasture and arable land) to
store carbon differs, and it has been suggested that land use can
be managed to sequester a further 1 Pg of carbon per year in
soils (Houghton, 2007); this potential has received considerable
scientific attention (Lal, 2008). However, this may not be eas-
ily achievable on a global scale owing to the complex biological
mechanisms that control the incorporation of organic carbon into
soil, as well as the influence of changing abiotic factors, such as
moisture, temperature, land use and nitrogen enrichment, which
also affect soil carbon pools (Six et al., 2006; Smith et al., 2008).
Forest soils are considered to be especially effective at storing
carbon, in part because of a high abundance of fungi in the soil
relative to bacteria, which favours carbon sequestration (Bailey
et al., 2002; De Deyn et al., 2008; Busse, 2009; Castro et al.,
2010).
To manage the soil microbial communities to increase car-
bon sequestration, it will be important to understand their ecol-
ogy and function. This is a challenge in itself, because of our
inability to characterise the species diversity and function of
soil microbial communities and our lack of theoretical prin-
ciples in microbial ecology, such as the definition of a species
and the factors driving community formation and structure
(Castro et al., 2010). Nevertheless, there is some evidence that
bacteria can be categorised on the basis of their carbon miner-
alisation capacity and can be divided into copiotrophic (char-
acterised by high growth rates on labile carbon and dominant
in nutrient-rich environments) and oligotrophic (slow-growing
and dominant in nutrient-limited ecosystems) species (Fierer
et al., 2007). It has been suggested that the acidobacteria are
oligotrophic, whereas the proteobacteria and the actinobacteria
form copiotrophic communities.
One may disagree that manipulating land use (e.g. changing
from arable land to forestry) and land management practices
(e.g. using low-nitrogen-input agriculture) may promote the
growth of oligotrophic communities. However, the ecological
strategies of other dominant microbial taxa need to be under-
stood. It is true that not all taxa in a phylum will be either copi-
otrophic or oligotrophic (Allison and Treseder, 2008) and, thus,
phyla alone may not be a predictor of carbon loss from the soil
(Fierer et al., 2007). It is therefore essential that we use rapidly
developing technologies such as high-throughput sequencing
to better understand soil microbial diversity. Moreover, emerg-
ing technologies such as metagenomics, metatranscriptomics,
metaproteomics and stable-isotope probing (SIP) must be used
to examine the physiological abilities and roles of individual
