Environmental Engineering Reference
In-Depth Information
How the stability of an ecosystem can be measured
According to Grimm and Wissel (1997), the stability concept is a collective
notion or term, which is defi ned via three fundamental properties: constancy
(a system staying essentially unchanged), resilience (the ability of a system
to return to the reference or dynamic state after a temporary disturbance),
and persistence (the ability of a system to persist through time).
Several attempts have been undertaken to investigate the relationship
between biodiversity and the stability properties of an ecosystem, using
different proxies, habitats or types and levels of disturbance (e.g., Loreau
et al. 2001, Balvanera et al. 2006, Isbell et al. 2009, Campbell et al. 2011,
Godbold et al. 2011). One of the hypotheses tested states that “higher
biodiversity promotes higher stability” (e.g., MacArthur 1955, Odum 1959,
Margalef 1969). Several decades after its formulation, there is still a lack of
comprehension regarding the relation between biodiversity and stability
(e.g., Worm et al. 2006, Ives and Carpenter 2007, Baraloto et al. 2010). One
of the major diffi culties relies on the selection and use of tools and measures
able to correctly “quantify” the system stability properties.
A few studies (e.g., Srivastava and Vellend 2005, Tilman et al. 2006, Bodin
and Wiman 2007) have tried to assess the connection between ecosystem
stability and services provision. In addition the results from several authors
(e.g. Hooper et al. 2005) have suggested that ecosystem functions are more
stable through time at relatively high levels of biodiversity.
Some authors (e.g., Winfree and Kremen 2009, Haines-Young and
Potschin 2010) have suggested that both the level and stability of ecosystems
tend to improve with increasing biodiversity through space and time,
importantly, although most of these studies were conducted in terrestrial
ecosystems (e.g., Kremen et al. 2002, Tilman et al. 2005), and there are
very few cases where this relationship has arisen for aquatic ecosystems
(e.g., Valdivia and Molis 2009). Transitional habitats, like estuaries, are
particularly challenging for many reasons all over the world (Pinto et al.
2013). Most important are: (1) biological communities under naturally
stressful conditions (Elliott and McLusky 2002); (2) biota under multiple
anthropogenic pressures (Wilkinson et al. 2007); (3) estuarine communities
characterized by low number of species and high species abundance (Elliott
and Quintino 2007), although their number is increasing due to invaders
(Nehring 2006).
In this sense, Tilman (1999), Lehman and Tilman (2000) and Tilman et
al. (2006) proposed the use of “temporal stability” (TS), defi ned as the ratio
of mean abundance to its standard deviation, to test the diversity-stability
hypothesis. Within this framework Pinto et al. (2013) suggest that the
diversity-stability relationships are neither linear nor monotonic in estuaries
due to their complexity. The observed stability results appeared to be more
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