The response of fish communities and stream habitat to four riparian harvest treatments was studied in north-central Minnesota to determine if riparian harvest with two different harvest systems degrades stream systems. Treatments included control (no harvest), riparian control, cut-to-length riparian thin, and tree length riparian thin. Fish and habitat data were collected from 50 m reaches above, within, and downstream of each treatment 1 year preharvest (1997) and 3 years postharvest (1998–2000). Repeated measures analysis revealed few effects due to treatment; however, there was a 6%–10% significant reduction in canopy cover. Percent fine sediments increased significantly (15%) system-wide following forest harvest and persisted through 2000. This increase in fine sediments was correlated with a decrease in fish biotic integrity (r = –0.31). Habitat and fish variables were influenced more by year-to-year variation than by harvest treatment, suggesting that factors operating at a broader basin-wide scale may influence fish and habitat or mask any site-level harvest effects in this low-gradient stream system. Residual riparian basal areas ≥12.3m2/ha along reaches ≤200 m in length may be adequate to protect fish and habitat in these low-gradient streams, but basin-wide effects of harvest deserve more scrutiny.
Gulf Stream System Assimilation Experiments: A Sensitivity Study
