Difference between revisions of "ECOSYSTEM"

Native Species and Biotic Communities

An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment (things like air, water and mineral soil), interacting as a system. These biotic and abiotic components are regarded as linked together through nutrient cycles and energy flows. As ecosystems are defined by the network of interactions among organisms, and between organisms and their environment, they can be of any size but usually encompass specific, limited spaces (although some scientists say that the entire planet is an ecosystem).

Ecosystems are controlled both by external and internal factors. External factors such as climate, the parent material that forms the soil, and topography control the overall structure of an ecosystem and the way things work within it, but are not themselves influenced by the ecosystem. Other external factors include time and potential biota. Ecosystems are dynamic entities—invariably, they are subject to periodic disturbances and are in the process of recovering from some past disturbance. Ecosystems in similar environments that are located in different parts of the world can have very different characteristics simply because they contain different species. The introduction of non-native species can cause substantial shifts in ecosystem function. Internal factors not only control ecosystem processes but are also controlled by them and are often subject to feedback loops. While the resource inputs are generally controlled by external processes like climate and parent material, the availability of these resources within the ecosystem is controlled by internal factors like decomposition, root competition or shading. Other internal factors include disturbance, succession and the types of species present.

Biodiversity affects ecosystem function, as do the processes of disturbance and succession. Ecosystems provide a variety of goods and services upon which people depend; the principles of ecosystem management suggest that rather than managing individual species, natural resources should be managed at the level of the ecosystem itself. Classifying ecosystems into ecologically homogeneous units is an important step towards effective ecosystem management, but there is no single, agreed-upon way to do this.

Desired Future Condition for Native Species and Biotic Communities

Native Species:
Native fish species and their habitats (including critical habitats) sustainably maintained throughout in each species’ natural ranges in the CRE.
• A healthy, self-sustaining populations of other remaining native fish with appropriate distribution (flannelmouth sucker, bluehead sucker, speckled dace, so that listing under the ESA is not needed.

Nonfish Biotic Communities:
Native non-fish aquatic biota and their habitats are sustainably maintained with ecologically appropriate distributions.
• Populations of native non-fish species (invertebrates and vertebrates, including Northern Leopard Frog).
- AMP support, actions and funding are limited to incorporation of dam operations which are conducive to restoration of extirpated species.
• Minimize the abundance and distribution of non-native species in the CRE.
• Sustainable dam-influenced aquatic, wetland, and springs plant communities and associated biological processes, including those supporting threatened and endangered species and their habitats.

CRE Riparian Domain:
Native riparian systems, in various stages of maturity, are diverse, healthy, productive, self-sustaining, and ecologically appropriate.
• Native, self-sustaining riverine wetlands, and riparian vegetation and habitat, with appropriate mixture of age classes.
• Healthy, self-sustaining populations of native riparian fauna (both resident and migratory).
• Habitat for sensitive species within the CRE
• Encourage the resolution of the taxonomic status of the Kanab ambersnail (e.g., completely describe the taxa and subspecies).
• Habitat for neotropical migratory birds, waterfowl, and other appropriate native bird species.
• Ecological functions of tributary mouths and riverside springs, including habitat for native species.