Biodiversity as an Ecosystem Service

    Biodiversity and Ecosystem Services (BES) was a termed coined in the 1990s to describe the essential benefits that ecosystems provide to humanity (e.g. Daily, 1997). This mainly looks at changes to patterns relevant to economic or cultural evaluation, and is important as it can describe the losses humans might face with decreasing biodiversity (Cardinale et al., 2012). Humanity prospers from many ecosystem services, including; diverse and numerous food sources (plants and animals), pharmaceutical products, waste decomposition and recycling, and cultural inspiration. In many cases biodiversity has been considered so important to human culture, and having such a large impact, that it has been itself called an ecosystem service (Mace, Norris and Fitter, 2012).

    This means that biodiversity is often viewed as an underlying factor driving ecosystem services; usually in this case the presence/absence of entire habitats or organism groups. A good example of this is that high biodiversity is required for the maintenance of mangrove forests, and these are important for local human settlements as flood protection (Cardinale et al., 2012).

A diagram produced by Cardinale et al., 2012, summarising several
 hundred studies. This shows the great effect biodiversity
has on increasing ecosystem services.

    Cardinale et al., 2012, reviews past papers on biodiversity loss and the effects this has on ecosystems - they find several consensus points on these effects, from a high number of studies. These include:

1. Analyses published since 2005 have shown that, as a general rule, reductions in the diversity of genes, species and groups of organisms reduces the efficiency by which whole communities capture essential resources (nutrients, light, water or prey; e.g. Cardinale et al., 2011; Worm et al., 2006). This actually seems very consistent across different groups, trophic levels and ecosystems (Cardinale et al., 2012). 
2. There is mounting evidence that high biodiversity increases the stability of ecosystem functions through time; for example total resource capture and biomass production are more stable in a diverse community (e.g. in Hector et al., 2010). However it is not known that biodiversity enhances all form of community stability, and has not yet been looked at in a more encompassing light (Ives and Carpenter, 2007).
3. Diverse communities (high biodiversity) are more productive as they contain key species with a large influence and differences in functional traits. This higher productivity is extremely important for human resource utilisation. However the actual extent to which some of these influences broadly contribute to ecosystem function has yet to be confirmed.
4. Functional traits of organisms have large impacts on the magnitude of ecosystem functions - this means that different traits are lost in extinctions, and this causes fluctuations in ecosystem functions. I.e. if a highly productive species, important to the ecosystem (and to humans as a resource), is lost then reductions in ecological process may follow (which can have negative impacts on human civilisations). However there is considerable variation in the impacts loss of particular traits can have on an ecosystem, and so we must know great detail about the species at risk of extinction and the possible effects of this to predict any consequences accurately (Suding et al., 2008).

    Several other consensus points on the effects of biodiversity on ecosystems and their services are also explored in Cardinale et al., 2012, demonstrating the large impact species loss can have. As ecosystem services can be extremely important to human culture and civilisation, and biodiversity underlies many of these services, maintenance of species number is of clear significance to humanity.