Plant community response to Artemisia rothrockii (sagebrush) encroachment and removal along an arid elevational gradient

Abstract

Questions Shrub expansion into alpine ecosystems worldwide raises important questions regarding the influence of shrub encroachment on alpine species diversity. The stress gradient hypothesis (SGH) predicts interactions will be competitive when resources are plentiful and the environment is benign, but that facilitative interactions will dominate when conditions are stressful. We asked how Artemisia rothrockii (sagebrush) encroachment in an arid mountain range is affecting alpine plant species there and how the plant community responds to the experimental removal of sagebrush at three sites along an elevational gradient. Location The White Mountains, California, USA (37°30′N, 118°10′W). Methods A shrub removal experiment was established at three elevations (2,900, 3,100 and 3,750 m) to evaluate how sagebrush interacts with alpine and sub‐alpine plant communities. Results The study sites experienced a strong drought over the 4 yrs of the experiment and plant cover declined overall. However, in the sagebrush removal treatment, cover of co‐occurring species increased at both the high‐elevation and low‐elevation sites, with no differences observed at the mid‐elevation site. Conclusions We observed the greatest inhibitory effects of sagebrush at high and low elevations, where plants experience the largest temperature and moisture stress, respectively, and no evidence of facilitation anywhere along the elevational gradient. These results demonstrate that while sagebrush has important influences on herbaceous species composition in the White Mountains, they are inconsistent with the classic predictions of the SGH.

Investigating Microtopographic and Soil Controls on a Mountainous Meadow Plant Community Using High‐Resolution Remote Sensing and Surface Geophysical Data

“…Finally, the proposed framework can potentially be useful for long‐term monitoring of meadow ecosystems. Understanding that functional groups can vary their response to plant encroachments, and that the nature of these interactions varies across environmental gradients (Kopp & Cleland, ), we can use accurate vegetation maps at high resolution to assess the local diversity and track the effect of plant encroachments—such as shifts and/or changes in community distribution due to disturbances such as early snowmelt and drought or associated with other perturbations (e.g., fire, logging). We also envision that this framework would serve as a bridge from plot‐scale experiments to watershed‐scale characterization without losing the natural spatial resolution at which interactions are observed.…”

Legacy effects post removal of a range-expanding shrub influence soil fungal communities and create negative plant-soil feedbacks for conspecific seedlings

“…Vol. : (0123456789) removal experiments to avoid significant disturbance to soil communities (Berlow et al 2003;Yin et al 2017;Kopp and Cleland 2018), however decaying roots likely influenced soil legacies.…”

Plant-Soil Feedbacks and Facilitation Influence the Demography of Herbaceous Alpine Species in Response to Woody Plant Range Expansion

“…interact with mycorrhizal fungi and free-living soil microbes (Weaver and Klarich, 1977;Nilsson et al, 1993;Wardle et al, 1998). Aboveground sagebrush removal led to the re-establishment of herbaceous cover (including K. macrantha and E. ovalifolium) after 4 years in the White Mountains suggesting potentially high levels of interspecific competition (Kopp and Cleland, 2018). However, indirect soil effects of sagebrush on alpine plant growth, a form of apparent competition, may be as strong or stronger than the direct effects of competition with sagebrush (Allen et al, 2018).…”