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W. Wallace Covington
Northern Arizona University
EcologyThinningAgroforestryRestoration ecologyBiology
118Publications
46H-index
7,626Citations
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Publications 116
Newest
#1Jason P. Kaye (PSU: Pennsylvania State University)H-Index: 33
#2Margot W. Kaye (PSU: Pennsylvania State University)H-Index: 18
Last. Peter Z. Fulé (NAU: Northern Arizona University)H-Index: 49
view all 5 authors...
Increasing tree density that followed fire exclusion after the 1880s in the southwestern United States (US) may have also altered nutrient cycles and led to a carbon (C) sink that constitutes a significant component of the US C budget. Yet, empirical data quantifying century-scale changes in C or nutrients due to fire exclusion are rare. We used tree-ring reconstructions of stand structure from five ponderosa pine–dominated sites from across northern Arizona to compare live tree C, nitrogen (N),...
1 CitationsSource
#1Scott R. AbellaH-Index: 23
#2Joseph E. Crouse (NAU: Northern Arizona University)H-Index: 13
Last. Judith D. Springer (NAU: Northern Arizona University)H-Index: 13
view all 4 authors...
A major challenge to advancing the science and practice of ecological restoration is working across large landscapes containing diverse sites that may respond differently to restoration. We conducted a 5-year restoration experiment, replicated across 9 sites spanning 3 soil parent material types within a 9,000-ha Pinus ponderosa forest landscape. We evaluated plant community response to restoration Pinus thinning, grazing, and aqueous smoke application. We measured vegetation before (2003) and 3...
6 CitationsSource
#1John Paul Roccaforte (NAU: Northern Arizona University)H-Index: 7
#2David W. Huffman (NAU: Northern Arizona University)H-Index: 17
Last. Joseph E. Crouse (NAU: Northern Arizona University)H-Index: 13
view all 7 authors...
Southwestern ponderosa pine forest ecosystems have become uncharacteristically dense as a result of intensive livestock grazing, logging, and fire exclusion, which have contributed to a buildup of fuels and increased vulnerability to high-severity, landscape-scale crown fires. In 2002, we implemented a replicated ecological restoration experiment to (1) quantify site-specific reference conditions, (2) analyze effects of elevation on forest structure, surface fuels, and canopy fuels, (3) test res...
24 CitationsSource
#1Christopher M. McGlone (NAU: Northern Arizona University)H-Index: 6
#2Michael T. Stoddard (NAU: Northern Arizona University)H-Index: 11
Last. W. Wallace Covington (NAU: Northern Arizona University)H-Index: 46
view all 6 authors...
Abstract Changes in the vegetative structure and diversity of ponderosa pine forests have generated interest in conducting ecological restoration projects to improve the overall forest health of these ecosystems. Ecological restoration prescriptions often consist of thinning trees to emulate pre-1870s forest structure followed by prescribed burning. Disturbances associated with ecological restoration can, however, promote invasion by nonnative species. We compared two northern Arizona ponderosa ...
5 CitationsSource
#1Elizabeth L. Kalies (NAU: Northern Arizona University)H-Index: 10
#2W. Wallace Covington (NAU: Northern Arizona University)H-Index: 46
Ecosystem stability has been of increasing interest in the past several decades as it helps predict the consequences of anthropogenic disturbances on ecosystems. Species may exhibit stability through compensation, with greatly fluctuating populations year to year but a consistent density response over time. Stability is increased when species with similar functional roles compensate for one another by responding differently to environmental change. In restoration projects, the objective is to re...
1 CitationsSource
#1Scott R. Abella (UNLV: University of Nevada, Las Vegas)H-Index: 23
#2E. Cayenne Engel (UNLV: University of Nevada, Las Vegas)H-Index: 8
Last. W. Wallace Covington (NAU: Northern Arizona University)H-Index: 46
view all 4 authors...
Abstract Invasions by exotic plant species can threaten forest ecosystems in numerous ways. Theories on relationships of exotic species invasions with native vegetation, resource availability, and disturbance could assist in managing exotic plants by identifying parts of the landscape and ecological conditions most susceptible to invasion. However, generality of these theories is complicated by considerable variation among landscapes and ecology of individual species. We assessed hypotheses on r...
9 CitationsSource
#1Elizabeth L. Kalies (NAU: Northern Arizona University)H-Index: 10
#2Brett G. Dickson (NAU: Northern Arizona University)H-Index: 19
Last. W. Wallace Covington (NAU: Northern Arizona University)H-Index: 46
view all 4 authors...
In western North American conifer forests, wildfires are increasing in frequency and severity due to heavy fuel loads that have accumulated after a century of fire suppression. Forest restoration treatments (e.g., thinning and/or burning) are being designed and implemented at large spatial and temporal scales in an effort to reduce fire risk and restore forest structure and function. In ponderosa pine (Pinus ponderosa) forests, predominantly open forest structure and a frequent, low-severity fir...
22 CitationsSource
#1Scott R. Abella (UNR: University of Nevada, Reno)H-Index: 23
#2Charles W. Denton (NAU: Northern Arizona University)H-Index: 3
Last. W. Wallace CovingtonH-Index: 46
view all 6 authors...
Maps of historical tree densities for project areas and land- scapes may be useful for a variety of management purposes such as determining site capabilities and planning forest thinning treatments. We used the U.S. Forest Service Region 3 terrestrial ecosystem sur- vey in a novel way to determine if the ecosystem classification is a useful a guide for estimating historical (1880) ponderosa pine (Pinus ponderosa) tree densities on a northern Arizona landscape. Based on sampling 53 sites spanning...
4 CitationsSource
#1Scott R. AbellaH-Index: 23
#2Charles W. DentonH-Index: 3
Last. Ross J. GuidaH-Index: 4
view all 8 authors...
Isolated forested mountains in deserts have numerous ecological and societal values, but land management practices (e.g., fire-regime alteration) and climate change can affect forest composition. We analyzed tree overstory-understory relationships on 123 sites in the Spring Mountains within the Mojave Desert near Las Vegas, Nevada, USA to assess three hypotheses. We hypothesized that: the tree species comprising understories are less tolerant of fire than species in overstories, reflecting land ...
#1Corinne A. Diggins (NAU: Northern Arizona University)H-Index: 6
#2Peter Z. Fulé (NAU: Northern Arizona University)H-Index: 49
Last. W. Wallace Covington (NAU: Northern Arizona University)H-Index: 46
view all 4 authors...
Forests adapted to frequent-fire regimes are being treated to reduce fuel hazards and restore ecosystem processes. The maintenance of treatment effects underfuture climatesis a critical issue. Wemodelled forest changeunder differentclimatescenariosfor100yearsonponderosapinelandscapesinthesouth-westernUSA,comparingmanagement regimes that included prescribed burning, tree cutting, and no-management. We applied the Forest Vegetation Simulator (1)initsstandardform,and(2)withmodificationsofreducedtre...
27 CitationsSource
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