Restoration of Plant Cover on Campsites in Subalpine Forests: Sawtooth Wilderness, Idaho.

摘要

This study assessed the effectiveness of restoration treatments in enhancing the growth of Vaccinium scoparium transplants and plants established from seed on six closed campsites in subalpine forests in the Sawtooth Wilderness, Idaho. In the primary experiment, the soil on all plots was scarified and amended with organic matter; plots varied regarding the type and amount of organic matter in the amendments, whether or not they were fertilized, and whether or not they were covered with a mulch blanket. In the second experiment, plots varied regarding whether or not they were scarified, amended with organic matter, or received supplemental water. Compared to an earlier study in similar forests in the Eagle Cap Wilderness, Oregon, survival and growth of Vaccinium scoparium transplants was high, regardless of treatment, as long as campsites were closed and soils were scarified. In the primary experiment, 92 percent of transplants were still alive after five years and most transplants had increased in size. This greater success may reflect the larger size of transplants used in the Sawtooth study (mean of 315 cm2). The most pronounced main effect of treatments in the primary experiment was the beneficial effect of fertilization with Biosol on the establishment and growth of seedlings, particularly graminoids. Certain combinations of mulch and type and amount of organic matter were more beneficial than other combinations, but none of these treatments had either consistent or substantial positive effects. Supplemental watering increased restoration success, suggesting that recovery is limited by water. Our results suggest that native vegetation can be restored on highly disturbed campsites in these forests. They also reinforce the importance of avoiding impact in the first place given the lengthy recovery periods required in these ecosystems and the intensive restoration efforts needed to speed recovery.