| This research was designed to determine the impacts of a variety of forestry management alternatives on stream ecosystems in three sets of replicated watersheds of the Ouachita Province in the Interior Highlands of Arkansas, USA. Macroinvertebrate species assemblages in a variety of substrates (gravel, bryophytes, bare stones, leaf packs, and large woody debris (LWD)) were the principal biota used as indicators of environmental quality, but bryophytes were also used in this way. Retention of particulate organic matter was evaluated for bryophyte patches, bare stones, and added trees. Several related but independent experimental designs were used to address a series of questions concerning effects of silvicultural methods. One design compared benthic macroinvertebrates among five different silvicultural methods applied to very small ({dollar}<{dollar}5 ha) watersheds: (1) clearcutting, (2) seed tree, (3) pine shelterwood, (4) group selection, and (5) pine single tree selection. In each treatment 10 m buffer strips were left on each side of the streams and adjacent uncut watersheds were used as controls. In another design, four watersheds (660 ha each) with different histories of management were compared: (1) no cutting in nearly a century, (2) uneven age management, (3) mixed uneven age and pine plantation, and (4) loblolly pine plantation. Oak and pine logs also were placed in these streams at the 660 ha cross-sections to compare them regarding macroinvertebrate colonization. Finally, LWD was added to 100 m reaches of four similar streams to evaluate effects of this on retention of coarse particulate organic matter and on macroinvertebrates. Invertebrates were more abundant and diverse in streams draining watersheds with the highest intensities of forest management (clearcuts, pine plantations). Bryophyte patches and large woody debris (LWD) provided enhanced retention of fine and coarse particulate organic matter, respectively, and preferred habitats for invertebrates. Bryophyte patches were less abundant in streams of disturbed watersheds. Since bryophyte patches are important as providers of food and refuge for invertebrates, bryophytes may deserve protection by watershed managers. Macroinvertebrates were sensitive indicators of intensity of forest management in these small watersheds. Apparently they benefit from resources lost from the terrestrial component of the watersheds. |
