Aquatic invertebrate-habitat relationships and stream channel cross section area change in response to streamside management zones in North Central Mississippi

Graduation date: 2005Presentation date: 2004-07-30The southern states lead the country in timber production and are subject to\ud Best Management Practices (BMPs) designed to mediate the effects of forest\ud harvesting on water quality. Small headwater streams on timberland in North\ud Central Mississippi have received little attention with respect to effectiveness\ud of the BMPs designed to protect them. With stand rotations of 25-30 years\ud and with some counties held in nearly 30% private industrial forestry\ud ownership, impacts of intensive forest management on water resources have\ud the potential to be large. In North Central Mississippi, I evaluated the\ud effectiveness of Streamside Management Zones (SMZs), corridors of the\ud riparian zone along the stream left unharvested, as a component of BMPs.\ud The streams sampled were low-order perennial headwaters either within a\ud clearcut with no SMZ, a clearcut with an SMZ, or a site that had not been\ud harvested. Aquatic invertebrate community composition, habitat and\ud substrate composition, and stream channel cross-section areas were evaluated\ud in 2002 and again in 2003. My objectives were 1) to describe the\ud invertebrates and habitat conditions at each site, 2) to determine if there are\ud relationships between invertebrates and water quality, cover metrics, or\ud relative amounts of substrate size fractions, and 3) to determine whether or\ud not there were detectable treatment effects on either substrate composition or\ud stream channel cross-section areas. Water quality, cover, and substrate size\ud classes were highly variable within each harvest treatment. No significant\ud differences were found downstream of harvest treatments for relative\ud distribution of substrate within each harvest treatment group. Even though\ud the habitat and substrate were highly variable, the invertebrate composition at\ud many sites was dominated by a single family, Chironomidae. Ordinations of\ud the presence of invertebrate taxa using non-metric multidimensional scaling showed a separation of the Reference and No-SMZ treatment groups for 2003,\ud indicating that treatment effects may only be expressed in the biota and not in\ud physical stream habitat characteristics measured by this study three to five\ud years after harvesting. Changes in stream channel cross-section area\ud occurred for all treatments, with Reference treatments degrading and SMZ\ud and No-SMZ treatments aggrading between 24 and 29 months after\ud harvesting treatments were established. Overall, No-SMZ treatments did not\ud have significant changes in stream channel cross-section between sampling\ud intervals, while Reference and SMZ treated streams changed significantly\ud throughout the study. High natural variability of the streams made it difficult\ud to discern differences in stream habitat parameters for each harvest treatment.\ud Differences between Reference and No-SMZ sites in the 2003 ordinations and\ud between No-SMZ and the other treatments for stream channel cross-sections\ud indicated that SMZs are functioning in these low-order streams