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Livestock Environmental Assessment and Performance (LEAP) Partnership
A review of indicators and methods to assess biodiversity – application to livestock production at global scale
the ecosystem level and landscape structure (Section 2.2.1) could be a state indicator at the landscape
level.
2.3.2.2 Structural dimension
The structural dimensions are often linked at the ecosystem level. Structure can relate to vegetation
structure, which is an indicator of ecosystem health in both grassland and forest ecosystems. In forest
ecosystems, a variety of species depend on the architecture of certain species of trees, called foundation
species (Ellison & Bank, 2005). The decline of such key foundation species due to various pressures
(e.g., outbreaks of invasive species and pathogens) threatens the whole ecosystem structure and several
processes involved in its functioning. Conversely, CO2 and climate change have an effect on the
ecosystem function (net energy productivity) which translates into a change in the vegetation structure
(Cramer et al., 2001). In all terrestrial ecosystems, the soil structure also plays a very important role. Soil
structural properties respond to abiotic (e.g., of the parent material, erosion, physical and chemical
processes) and biotic (e.g., organic carbon, soil community of mycorrhizal fungi, micro and macro
arthropods) factors (Bronick & Lal, 2005). Soil structure is often expressed as the degree of stability of
aggregates. Both over-compaction and porosity represent alteration of the soil structure. The soil
structure is closely related to its function (carbon sequestration in particular, Silver et al. 2000) but also
to the above ground biomass and functioning of the whole ecosystem (Wardle et al., 2004). In aquatic
ecosystems, the food web and size structure are key properties for the stability of pelagic ecosystems
(Verity & Smetacek, 1996).
2.3.2.3 Functional dimension
Function is a crucial dimension of ecosystems. By definition, ecosystems are networks and involve many
processes, e.g., fluxes of energy and nutrients, biomass production and decomposition. From a human
perspective, these processes are ecosystem services, i.e. or indirect benefits of ecosystems for human
(Millennium Ecosystem Assessment, 2005). For example, biomass production in a grassland ecosystem
represents forage production for cattle. Livestock are part of agroecosystems and they are both providers
(e.g. production, encroachment control) and user (e.g. fertility, water cycling) of ecosystem services
(Swinton et al., 2007).
The functioning of ecosystems is associated with their health and resilience, and with high
biodiversity levels (species diversity in particular, Hooper et al. 2005). Human pressures on biodiversity
have led to ecosystem degradation (Vitousek et al., 1997). There are many evidences that stressed and
degraded ecosystems have become incapable of supplying services to the same level than in the past
(Noble & Dirzo, 1997; Rapport et al., 1998). The pressures that livestock have put on ecosystem have
resulted in ecosystem degradation and diminution of the services provided by the ecosystems (Harrison
et al., 2010). Conversely, well managed grassland production systems can maintain healthy ecosystems
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