Abstract

Restoration biology is a relatively new branch of biology and many restoration practices, while transferable, require some degree of tweaking. This is because the same plant ecosystem might be at different levels of ecological ruin and heavily influenced by everything from soil quality, to mountain aspect and sunshine levels, to fog-interception rates. Additionally, different plants of the same ecosystem might respond differently to varying treatments. The plants of this study are located on Santa Rosa Island, off the coast of Santa Barbara in Southern California. For the restoration at Soledad Ridge, the treatments include three combinations of drip-irrigation lines, erosion-control wattles, and fog-catching fences. For this study Coyote brush (Baccharis pilularis) and Purple-needle grass (Stipa pulchra) were assessed for growth. This was done by collecting applicable plant measurements (stem diameter, height, and canopy length and width) in 2017 and by both (1) comparing the numbers to measurements taken in 2016 and (2) comparing the differences among experimental treatments. The results show that B. pilularis does best in the fog fence treatment for all measurements, even after excluding casualties. Meanwhile, S. pulchra survivors do just as well in the wattle treatment as compared to the fog fence treatment after casualties are taken into account, but overall survivorship is better in the control treatment. This suggests that restoration of B. pilularis should include fog fences, but restoration of S. pulchra does not require additional measures beyond the control treatment of irrigation only.

Abstract

Restoration biology, the practice of healing a damaged landscape to that of a functioning ecosysytem, is as variable a science as they come. Restoration treatments may take into account precipitation, symbiotic relationships, microclimate, degree of plant succession, and soil conditions. The most effective restoration is based on experimental research. Such is the goal for the Cloud Forest Restoration Project on Santa Rosa Island, within Channel Islands National Park off the coast of Southern California. Here, plants receive the majority of their moisture from fog, including perennial Coyote brush (Baccharis pilularis) and Purple-needle grass (Stipa pulchra) in experimental plots. The experimental plots are located on Soledad Ridge, which is particularly damaged due to extreme levels of soil erosion. The effort to establish B. pilularis and S. pulchra include treatments aimed at increasing captured fog through fog-harvesting fences and reducing erosion with wattles. The treatments were assessed by comparing growth of B. pilularis and S. pulchra for two consecutive years. This was done by collecting applicable plant measurements (stem diameter, height, and canopy length and width) in 2017 and 2018 and by both (1) comparing the numbers to initial measurements taken in 2016 and (2) comparing the differences among experimental treatments. The results show that survivorship and growth gains are greatest for B. pilularis in the combination fog and wattle treatment, but less pronounced for S. pulchra.