A Comparison of the Ecological Integrity of Headwater Streams Draining Harvested and Un-Harvested Watersheds in the Western Mountains of Maine, U.S.A.

Physical, chemical, and biological characteristics of four headwater streams draining forested watersheds were compared to determine the effectiveness of Riparian Management Zones (RMZs) in protecting aquatic ecological integrity from the effects of forest harvesting. Two of the watersheds were harvested with a 30% sheltenvood cut and a 75 foot buffer was left adjacent to the streams. The other two watersheds were un-harvested and were used as reference conditions for comparison with the harvested watersheds. General environmental conditions in these four headwater streams during the study period were characterized as follows. Each stream was located within a mixed- wood forest dominated by paper birch, balsam fir, and red spruce. Stream bankfull widths averaged 2.3 m to 4.2 m, mean dissolved oxygen (DO) concentrations were 9 to 10 mgL, mean pH values ranged from 7.0 to 7.2, mean nitrate (No33 concentrations were \u3c0.5 mg/L, mean turbidity concentrations were \u3c0.6 NTU, mean temperatures were 11 to 12 C, mean conductivity ranged from 24 to 32 pS/cm, and TSS values were generally below detection limits. Densities of brook trout ranged from 2 to 47 individuals per 200 m reach, macroinvertebrate densities ranged from 20 to 235 individuals per 0.1 m2, and pieces of Large Woody Debris (LWD) per 200 m reach ranged from 42 to 100. In general, few clear, strong differences were found when comparing the Reference and Harvest streams. The physical habitat data were within the range of normal variation. However, the high variability of LWD, macroinvertebrate, and fish data analyzed between streams made it difficult to differentiate treatment effects. Overall, more data are required in order to determine the effects of harvesting within headwater watersheds. Further research is recommended that will increase the duration, replication, and range of treatments found in this study, as well as include a focus on baseline data collection and storm-water monitoring