Seedling ecology and restoration of blackbrush (Coleogyne ramosissima) in the Mojave Desert, United States

Restoration Ecology
By: , and 

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Abstract

Increases in fire frequency are disrupting many ecological communities not historically subjected to fire. In the southwestern United States, the blackbrush (Coleogyne ramosissima) community is among the most threatened, often replaced by invasive annual grasses after fire. This long-lived shrub is vulnerable because it recruits sporadically, partially due to mast seeding and the absence of a seed bank. The goal of this study was to evaluate if shrub restoration can be enhanced by identifying and ameliorating recruitment limitations. Specifically, we tested the effect of encapsulating seeds in predation-deterring “seed balls.” We also tested the effects of nurse plants and mammalian exclusion cages on seedling emergence, growth, and survivorship. These experiments were conducted in a full-factorial design across three sites differing in elevation. Over 2 years, 13% of all planted seeds emerged and the effect of seed balls was overwhelmingly negative because of low emergence. Nurse plants had overall positive effects at Low Elevation, but negative effects at Mid- and High Elevation. Emergence and survival were highest in caged plots everywhere, and effect sizes increased with elevation. Interactions between the cage and the nurse plant treatments indicated that nurse plants tended to attract mammalian predators, lowering emergence and seedling survivorship, particularly at higher elevations. Findings conform to the stress-gradient hypothesis in that interactions among seedlings and mature plants shifted from facilitation to competition as environmental stress decreased with increasing elevation, suggesting that they are transferable to ecologically similar communities elsewhere. Knowledge of site-specific recruitment limitations can help minimize ineffective restoration efforts.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Seedling ecology and restoration of blackbrush (Coleogyne ramosissima) in the Mojave Desert, United States
Series title Restoration Ecology
DOI 10.1111/rec.12128
Volume 22
Issue 5
Year Published 2014
Language English
Publisher Society for Ecological Restoration
Contributing office(s) Western Ecological Research Center
Description 9 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Restoration Ecology
First page 692
Last page 700
Country United States
State California;Nevada
Other Geospatial Mojave Desert