Browsing by Subject "Riparian forests"

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    Channel, Riparian and Catchment Features as Predictors of Wood Abundance in Low Gradient, Agricultural Streams
    (University of Minnesota Duluth, 2002) Johnson, Lucinda B; Host, George E; Richards, Carl
    Wood is an important component of small to medium streams in forested regions, but has been little studied in agricultural areas. Although wood habitat has been shown to be an important factor controlling macroinvertebrate biodiversity in agricultural regions of the Midwestern U.S., there is little information on how much wood is available and what factors control its abundance and distribution. The goals of this study were to: 1) characterize the abundance, size, and distribution of wood in low gradient streams in a predominantly agricultural region, and 2) quantify the relative influence of reach- and catchment-scale factors on the abundance and distribution of wood in these streams. Standing stocks of wood were quantified in 49 stream reaches in the Saginaw Basin of central Michigan, USA. An array of stream channel, riparian zone, and catchment features were quantified. Multiple regressions were conducted to predict standing stocks from explanatory variables at three spatial scales. Features at the local scale (e.g., bank-full width, % open canopy) had a large influence on the density and size of accumulations, and a moderate influence on wood abundance. In contrast, riparian and catchment features including riparian vegetation type, link number, % urban land use in the catchment, and topographic heterogeneity exerted greater control over wood abundance and the mean size of wood accumulations. The differences in the factors predicting wood standing stocks versus accumulation density are probably related to the presence of structures that entrain wood into accumulations. In contrast, wood standing stocks reflect current and past land use practices, as well as underlying processes (e.g., hydrologic regime) controlled by landforms. Patterns in wood standing stock and distribution differ from those observed in high gradient regions, and low gradient streams in forested regions. This has important implications for ecosystem processes and management of headwater streams in agricultural regions.
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    Wildlife species: responses to forest harvesting and management in riparian stands and landscapes
    (University of Minnesota Duluth, 2001) Hanowski, JoAnn M; Danz, Nicholas P; Lind, Jim; Niemi, Gerald J; Wolter, Peter T.
    Breeding birds were surveyed in five watersheds in northern Minnesota for four years. In three watersheds (Knife, Pokegama, Cloquet) 12, 6 to I 0 acre plots were established. In two watersheds (Knife, Gooseberry) one large(> 40 acre) plot was established. Plots were established to assess breeding bird response to harvest type and J:iarvest method in riparian forests. Treatments in the Pokegama watershed included removal of basal area to 25-35 ft within 100 ft of either side of the stream with two different harvest methods (grapple skidding and cut-to-length systems). Uplands adjacent to riparian buffers were clearcut and three total (no harvest) plots were maintained in the watershed as well as three uncut riparian control plots. Before harvest data were collected in 1997, harvest was completed in the fall of 1997, and after harvest data collected in 1998, 1999 and 2000. Treatments in the Knife watershed ranged from clearcut in the riparian area to 25-35 ft residual basal area within 100 feet on one side of the stream. Uplands adjacent to riparian buffers were clearcut and three total (no harvest) plots were maintained in the watershed as well as three uncut riparian control plots. Harvests were not completed on all sites because of poor winter harvest conditions in 1997, 1998 and 1999. Breeding bird data have been collected in all years and will be collected in 200 I if all sites are harvested within this time frame. Treatments on sites in the Cloquet watershed were designed to examine bird response to harvest in the riparian area by leaving residual basal area ( 40 ft2) in either a scattered or clumped pattern. Uplands adjacent to riparian buffers were clearcut and three total (no harvest) plots were maintained in the watershed as well as three uncut riparian control plots. Harvests were not completed on all sites because of poor winter harvest conditions in 1997, 1998 and 1999. Breeding bird data have been collected in all years and will be collected in 2001 if all sites are harvested within this time frame. Bird surveys were also completed on two large sites in Lake County. One site, the Gooseberry was harvested, but the Knife River site was not. No statistical analyses were completed on these data and no additional studies are planned. In addition to breeding bird surveys, two additional tasks were completed and results were presented in the previous biennial report (Louisiana Waterthrush and riparian landscape statistics for the forested regions of Minnesota. No new information is presented in this report on those tasks.