What is is ecological stability and how many ways may it promote sustainibility?
Tuscan landscape, looking east from Sienna, Italy toward Etruria. JVS, 2004
Dialectical approach to understanding how to work with nature.
|Niches to fill.
Dr. Paul Colinvaux
Every species has its niche
ecological, analytical, reductionist, abstract
Dr. G. Tyler Miller
Community Structure: Appearance & Species diversity, (2005)
biological, descriptive, integrative, visual
|Diversity to nourish.
|NICHE: a recessed space
|New tree: a nurse log is space
An ecologists view of lifes complexity
based on how a species
I Introduction explains "earning ones keep"
II. Limitations inherent
in Carrying Capacity
Niche is a means to understand
Ecologists describe the structure of a community in terms of its physical appearance, species diversity, species abundance, and niche structure.
Differences at boundaries between two ecosystems result in edge effects.
Species diversity on continents declines with distance from the equator (latitude). In marine communities, species diversity varies with depth and pollution levels. In terrestrial communities, species diversity increases with increasing solar radiation, increasing precipitation, decreased elevation, and pronounced seasonal variations.
MacArthur and Wilson's species equilibrium model predicts that species diversity will increase with island size and with proximity to a mainland. Field experiments have supported the model.
Birds are excellent indicator species and can serve as an early warning of damage to a community.
The decline of a keystone species can cause a ripple effect through an ecosystem.
7-3 Species Interactions: Competition and Predation
Disturbances or changes in environmental conditions disrupt an ecosystem or community and affect its species diversity and stage of succession.
According to the intermediate-disturbance hypothesis, communities that experience fairly frequent but moderate disturbances have the greatest species diversity.
Miller, Chapter 7, pp. 140-157
The chapter's importance lies in the fact that it suggests signals we need to read if we are to understand the fitness of the ecological system to sustain, both human and non-human needs.
The chapter establishes two kinds of capacity:
Paradox of ecosystem stability as it emerges out of competitive behavior, partitioning and symbiotic arrangements to accustom creatures to adapt to losses of or changes in keystone species.
Adaptive responses are needed to both changes in habitat and changes in species mixture.
7-6 Ecological conditions promote both:
Stability and Sustainability
Rachel Carson's, Edge of the Sea
The stability of communities is maintained by constant dynamic change in response to changing environmental conditions. Three aspects of sustainability in living systems are inertia, constancy, and resilience. The exact relationship between species diversity and these aspects of ecosystem stability is still under investigation. However, the precautionary principle suggests that we should prevent damage to the environment, even if some cause-and-effect relationships are not fully understood.