River Ecology and Restoration - River Dynamics and Integrated River Management - page 646

(a)
(b)
Fig. 10.20 (a) High sediment concentration in a stream in Taiwan, southeastern China, which results in low
transparency, low dissolved oxygen, and sediment coating the substrate; (b) Turbid seawater with high concentration
of sediment impacts on fish and invertebrate communities (See color figure at the end of this topic)
The Pennsylvania Department of Environmental Quality found that “dams of this nature are inherently
hazardous and cannot be permitted”. The Department therefore orders “to restore the stream to a
free-flow condition by removing all wood and brush forming the dams from the stream channel”. The
beaver dam and the life of beavers on fish in their “reservoir” is a part of the ecology, which increases the
diversity of habitats. The landlord Mr. R. Devries pronounced on behalf of the beavers that “the Spring
Pond Beavers have a right to build their unauthorized dams as long as the sky is blue, the grass is green
and water flows downstream. They have more dam rights than humans do to live and enjoy Spring Pond.
If the Department of Natural Resources and Environmental Protection lives up to its name, it should
protect the natural resources (Beavers) and the environment (Beavers' Dams).
Riparian vegetation, in general, tends to be resilient. Despite the fact that a flood may destroy a mature
cottonwood forest, the conditions it leaves behind are usually those of a nursery, so a new forest can be
established, and, thus, the riparian ecosystem is increased (Brady et al., 1985). Having developed
characteristics such as high biomass and deep established root systems, the riparian forest systems have
adapted to many types of natural stresses. Due to this adaptation, small and frequent droughts, floods,
and other natural disruptions are of little consequence to the systems. When an unexpected serious stress
occurs like fire, then the effect is only local and does not affect the community on a larger scale.