Biocentric patterns

Biocentric patterns

·         What influences the periods of existence and decline within the biocentric? 

·         What factors are at play within biocentric obsolescence?

Diversity provides insurance against change in functioning under extreme or novel conditions.

Species diversity not only stabilizes ecosystem processes in the face of annual variation in environment but also provides insurance against drastic change in ecosystem structure or processes in response to extreme events (Walker 1992, chapin et al. 1997). Any change in climate or climatic extremes that is severe enough to cause extinction of one species is unlikely to eliminate all members from a functional type (Walker 1995). The more species there are in a functional type, the less likely it is that any extinction event or series of events will have serious ecosystem consequences (Holling 1986).

Differences in environmental response among functionally different species may accentuate ecosystem change.

In contrast to the buffering provided by ecologically similar species, species that differ in their response to the environment and in their effects on ecosystem processes can make ecosystems vulnerable to change. Rising concentrations of atmospheric co2 for (eowensby et al. 1996). This in turn, can shift the competitive balance from grasses to shrubs, promoting shrub encroachment into grasslands and savannas and causing replacement of one biome by another. Global environmental change is causing many ecosystems to experience novel conditions of nitrogen deposition and atmospheric co2 concentrations. If the principles discussed here apply broadly, we can expect that the diversity of natural ecosystems will be crucial in determining the biotic properties of ecosystems (i.e the diversity of functional types) and the vulnerability to change ( the buffering provided by diversity within functional types).

Summary

The species diversity of earth is changing rapidly due to frequent species extinctions (both locally and globally), introductions, and changes in abundance. We are, however, only beginning to understand the ecosystem consequences of these changes. Many species have traits that strongly affect ecosystem processes through their affects on the supply or turnover of limiting resources, microclimate, and disturbance regime. The impact of these species traits on ecosystem processes depends on the abundance of a species, its functional similarities to other species in the community, and species interactions that influence the expression of important traits at the ecosystem scale. Diversity per se may be ecologically important if it leads to complementary use of resources by different species or increases the probability of including species with particular ecological effects. Because species belong to the same functional type generally differ in their response to environment, diversity within a functional type may stabilize ecosystem processes in the face of temporal variation or directional changes in environment, introduction of functionally different species to an ecosystem, in contrast, may accelerate the rate of ecosystem change. The effects of species traits on ecosystems processes are generally so strong that changes in the species composition or diversity of ecosystems are likely to alter their functioning, although the exact nature of these changes is frequently difficult to predict.