Hamman S.T.,University of Texas at Austin |
Hamman S.T.,Center for Natural Lands Management |
Hawkes C.V.,University of Texas at Austin
Restoration Ecology | Year: 2013
The restoration of disturbed ecosystems is challenging and often unsuccessful, particularly when non-native plants are abundant. Ecosystem restoration may be hindered by the effects of non-native plants on soil biogeochemical characteristics and microbial communities that persist even after plants are removed. To examine the importance of soil legacy effects, we used experimental restorations of Florida shrubland habitat that had been degraded by the introduction of non-native grasses coupled with either mechanical disturbance or pasture conversion. We removed non-native grasses and inoculated soils with native microbial communities at each degraded site, then examined how habitat structure, soil nitrogen, soil microbial abundances, and native seed germination responded over two years compared to undisturbed native sites. Grass removal treatments effectively restored some aspects of native habitat structure, including decreased exotic grass cover, increased bare ground, and reduced litter cover. Soil fungal abundance was also somewhat restored by grass removals, but soil algal abundance was unaffected. In addition, grass removal and microbial inoculation improved seed germination rates in degraded sites, but these remained quite low compared to native sites. High soil nitrogen persisted throughout the experiment regardless of treatment. Many treatment effects were site-specific, however, with legacies in the more degraded vegetation type tending to be more difficult to overcome. These results support the need for context-dependent restoration approaches and suggest that the degree of soil legacy effects may be a good indicator of restoration potential. © 2012 Society for Ecological Restoration International.
Meek M.H.,University of California at Davis |
Wells C.,University of California at Davis |
Tomalty K.M.,University of California at Davis |
Ashander J.,University of California at Davis |
And 14 more authors.
Biological Conservation | Year: 2015
The potential for extirpation of extremely small populations (ESPs) is high due to their vulnerability to demographic and environmental stochasticity and negative impacts of human activity. We argue that conservation actions that could aid ESPs are sometimes delayed because of a fear of failure. In human psychology, the fear of failure is composed of several distinct cognitive elements, including "uncertainty about the future" and "upsetting important others." Uncertainty about the future is often driven by information obstacles in conservation: information is either not easily shared among practitioners or information is lacking. Whereas, fear of upsetting important others can be due to apprehension about angering constituents, peers, funders, and other stakeholders. We present several ways to address these fears in hopes of improving the conservation process. We describe methods for increased information sharing and improved decision-making in the face of uncertainty, and recommend a shift in focus to cooperative actions and improving methods for evaluating success. Our hope is that by tackling stumbling blocks due to the apprehension of failure, conservation and management organizations can take steps to move from fear to action. © 2015 Elsevier Ltd.
Kronland W.J.,St. Cloud State University |
Kronland W.J.,Center for Natural Lands Management |
Restani M.,St. Cloud State University
Canadian Field-Naturalist | Year: 2011
We investigated how post-fire salvage logging of Ponderosa Pine (Pinus ponderosa) affected populations of cavity-nesting birds and small mammals in southeastern Montana in 2004 and 2005. We examined two salvage and two control plots with three point-count stations and one small mammal trap site randomly distributed across each plot. We used point counts and distance sampling methods to estimate density of cavity-nesting birds on each treatment. We also searched each plot for nests and used program MARK to construct a set of candidate models to investigate variations in nest survival related to treatment, year, and time. We used live traps arranged in webs centered on trapping sites and distance sampling methods to estimate small mammal density. Habitat characteristics were also quantified on each plot. Density of all cavity-nesting birds combined and of Hairy Woodpeckers (Picoides villosus) in particular were higher on the control than the salvage treatment. Density of large trees and abundance of active cavities were higher on the control treatment. Nest cavities on the salvage treatment were most often located in non-logged watersheds. Nest survival estimates were uniformly high, with only marginal variations attributed to treatment and year. Density of Deer Mice (Peromyscus maniculatus) was higher on the salvage than the control treatment, reflecting the amount of downed woody debris created during harvest.
Warrick G.D.,Center for Natural Lands Management
Southwestern Entomologist | Year: 2012
Annual pitfall trapping during a 10-year period indicated that outbreaks of false chinch bugs, Nysius raphanus Howard, occurred in 2005, 2009, and 2010 in the southern San Joaquin Valley of California. During these outbreaks, feeding by false chinch bugs appeared to cause widespread damage to rangeland shrubs. In 2009, a study was initiated to compare survival between shrubs infested by false chinch bugs and shrubs not infested. Fifty-one spiny saltbush, Atriplex spinifera J.F. Macbr. shrubs (<0.5 m in height) were selected, of which 26 had been infested and 25 had not been infested by false chinch bugs. Fifteen months later, survival of the false chinch bug-infested shrubs (22%) was significantly less (P < 0.001) than non-infested shrubs (96%). Results indicated that false chinch bugs (during outbreak years) can significantly depress survival of young saltbush shrubs.
Hasselquist E.M.,Center for Natural Lands Management |
Hasselquist E.M.,Umea University |
Hasselquist N.J.,University of California at Riverside |
Hasselquist N.J.,Swedish University of Agricultural Sciences |
And 2 more authors.
Restoration Ecology | Year: 2013
Invasive non-native plants pose a ubiquitous threat to native plant communities and have been blamed for the decline of many endangered species. Endangered species legislation provides legal instruments for protection, but identifying a general method for protecting endangered species by managing non-natives is confounded by multiple factors. We compared non-native management methods aimed at increasing populations of an endangered forb, Ambrosia pumila, and associated native plants. We compared the effects of a grass-specific herbicide (Fusilade II), hand-pulling, and mowing in two degraded coastal sage scrub sites in southern California, U.S.A. At both sites, hand-pulling had the greatest effect on non-native cover, and correspondingly resulted in the greatest increase in A. pumila stems. Fusilade II application also led to an increase in A. pumila, but was not as effective in controlling non-native plants as hand-pulling and its effect varied with the dominant non-native species. Mowing was not effective at promoting A. pumila, and its effect on non-native cover seemed to be related to rainfall patterns. Although some methods increased A. pumila, none of our treatments simultaneously increased cover of other native plants. Hand-pulling, the most effective treatment, is labor intensive and thus only feasible at small spatial scales. At larger scales, managers should take an experimental approach to identifying the most appropriate method because this can vary depending on the specific management objective (endangered species or whole native community), the dominant non-natives, yearly variation in weather, and the timing of treatment application. © 2012 Society for Ecological Restoration.