Establishing seed islands for native forb species on rangelands using N-Sulate ground cover fabric

Abstract

Native forbs are an integral component of native rangelands in Western North America. Reseeding forbs in degraded rangelands can be difficult and costly with varying success. One method for reseeding rangeland vegetation is the creation of “islands.” Using this technique, seedings are concentrated in areas with the highest probability for success, creating self-sustaining populations of reproducing individuals. The purpose of our study was to establish islands of native forbs in big sagebrush (Artemisia tridentata Nutt. [Asteraceae]) communities in central Utah. We used a lightweight ground cover fabric (N-Sulate) to increase soil moisture and temperature for enhancing seedbed conditions. Fourteen species of native forbs and 1 native grass were planted on 4 sites using a randomized block design with covered (N-Sulate ground cover fabric) and non-covered variations, replicated over 2 y. We collected species density and ground cover data 1 y, 2 y, and 5 y following implementation. Eight species exhibited increased first year seedling density with ground cover fabric; 5 species emerged equally well in both covered and non-covered plots. Overall, ground cover fabric did aid in emergence of some species but did not produce any long-term effects on native forb populations. This fabric increased cheatgrass (Bromus tectorum L. [Poaceae]) and annual weeds, especially on drier sites. Regardless of site, species, or ground cover fabric treatment, native forb islands did not establish long-term. Establishment success may be improved with herbicide application to control cheatgrass and annual weeds, and with a more careful species selection that matches ecological conditions of planting sites.