Influences of Logging History and Stream pH on Brook Trout Abundance in First-Order Streams in New Hampshire

Abstract

In New England streams, both logging and acidification may influence native populations of brook trout Salvelinus fontinalis. We assessed the relationship between these factors and brook trout abundance in 16 first-order streams that had been logged 6 to more than 30 years prior; we quantitatively sampled fishes and collected habitat and water chemistry data from these streams. Logging history (years since harvest) was negatively correlated with substrate embeddedness, suggesting that this aspect of physical habitat quality improves with forest recovery. Brook trout density and biomass, however, were negatively correlated to years since logging. In contrast, stream pH (ranged from <6 to >7 during low-flow conditions in August) was positively correlated with trout density and biomass. These results suggest that forest recovery alone may not result in across-the-board increases in brook trout abundance and that among-site variation in stream chemistry needs to be accounted for when assessing the effects of land-use on trout populations in the New England region.