Riparian input and hydrologic transport of organic seston along a prairie river.

摘要

In stream communities, inputs from riparian forests serve as a source of energy for the aquatic consumers. I examined variability of riparian cover in the Little Washita River, OK. (Chapter 1), as well as in-stream availability of particulate organic matter along the length of this prairie river at baseflow and following short-term flood events (Chapter 2). I also evaluated the resilience of aquatic macroinvertebrates communities, specifically those which use the suspended organic particles (Chapter 3).; Using two spatial scales of observation, I examined the relationship between forest cover and availability of coarse particulate organic matter within the river. The percentages of whole leaves in transport at six sites during summer and fall were best explained by the percent of riparian forest in 500 m and 1000 m reaches upstream of the sites, as viewed by remote sensing imagery. Field observations of overhead cover did not significantly correlate with the amount of whole leaves in transport at the sites. I conclude that longer reach lengths than those generally considered are serving as possible source areas of detrital inputs.; I quantified the availability of suspended and benthic organic matter along the length of river at baseflow and after floods. The organic content of benthic materials declined with distance downstream and following floods differed from baseflow amounts only in the headwaters. Fines (0.01-0.36 mm) comprised the largest amount of biomass of organic materials, and after floods, increased amounts were suspended downstream. Availability of suspended coarse organic particles ({dollar}>{dollar}1.0 mm) generally decreased with distance downstream, although following floods, amounts were reduced in headwaters and increased downstream.; Macroinvertebrate densities and community composition were examined at three spatial scales; among reaches separated by 2 km, within reaches and within quadrats. Initially, there were no significant differences in community composition or total densities among reaches along the gradient. After substrata disturbance, recolonized areas were found to have similar macroinvertebrate densities at large scales but at the finer scale, within the disturbed quadrats, there were significant differences. This suggests that the scale of observation can influence evaluation of the resilience of the community.