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At least 37 records · Page 2Linked to original sources
USGS2017

Payments for carbon sequestration to alleviate development pressure in a rapidly urbanizing region

The purpose of this study was to determine individuals' willingness to enroll in voluntary payments for carbon sequestration programs through the use of a discrete choice experiment delivered to forest owners living in the rapidly urbanizing region surrounding Charlotte, North Carolina. We examined forest owners' willingness to enroll in payments for carbon sequestration policies under different levels of financial incentives (annual revenue), different contract lengths, and different program administrators (e.g., private companies versus a state or federal agency). We also examined the influence forest owners' sense of place had on their willingness to enroll in hypothetical programs. Our results showed a high level of ambivalence toward participating in payments for carbon sequestration programs. However, both financial incentives and contract lengths significantly influenced forest owners' intent to enroll. Neither program administration nor forest owners' sense of place influenced intent to enroll. Although our analyses indicated that payments from carbon sequestration programs are not currently competitive with the monetary returns expected from timber harvest or property sales, certain forest owners might see payments for carbon sequestration programs as a viable option for offsetting increasing tax costs as development encroaches and property values rise.

Georgia, North Carolina, Tennessee, Virginia, Sout↗
USGS2018

“Naturalness” in designated Wilderness: Long-term changes in non-native plant dynamics on campsites, Boundary Waters, Minnesota

Wilderness areas in the United States are preserved for their untrammeled naturalness and opportunities for unconfined recreation. The Boundary Waters Canoe Area Wilderness has these qualities, but long-term recreation visitation pressures on campsites can cause significant ecological changes. This article explores changes on campsites, specifically examining non-native plant ecology over 3 decades. The research replicates a 1982 study analyzing vegetation composition and cover on campsites and environmentally paired controls. Camping activities have removed substantial tree cover on campsites, altering their ecological conditions and perceived wilderness character. Over the span of 32 years, the number of non-native plant species found on campsites has not risen, although their mean relative cover has increased significantly and they have spread to more sites. Of the 23 non-native herbs and grasses found on the campsites, only Cirsium arvense is considered a noxious weed by the state of Minnesota. Other noninvasive, non-native plants fall into a gray area in the context of "naturalness" for an area protected as Wilderness because they provide some positive ecological services even as they degrade wilderness character. Thus, wilderness managers face a difficult challenge in coping with the long-term impacts of visitor use on wilderness conditions and character.

Minnesota↗
USGS1995

Competitive relations between Douglas-fir and Pacific madrone on shallow soils in a Mediterranean climate

A large area of Pacific Coast forests is characterized by shallow soil, with negligible rainfall in the growing season. This study explores water-seeking strategy on such a site. We studied availability of bedrock water and its effects on growth and ecophysiology of 11-yr-old planted Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) and sprouting Pacific madrone (Arbutus menziesii Pursh). The study was carried out at three regulated densities of madrone sprouts on shallow (<50 cm) residual soils in southwest Oregon. Total bedrock water depleted from March to September, as observed in drill holes by neutron probe, did not differ significantly (P > 0.05) among three densities of madrone. However, cover in plots with the highest density of madrone (1322 sprout clumps/ha) depleted 50 mm of water from the 1.5 m layer by June, whereas vegetation on lower density treatments withdrew 15-28 mm by June, with later withdrawal distributed more uniformly through the growing season. Madrone density significantly affected basal diameter (P a?? 0.0001) and height growth (P a?? 0.002) of Douglas-fir. Madrone was consistently taller than Douglas-fir in all plots. The height of 11-yr-old madrone sprout clumps (424-465 cm) did not differ significantly among densities. Madrone leaf area index and biomass were higher at the high density of madrone than at medium density (P a?? 0.045, LAI; P a?? 0.001, biomass). Physiological advantages and rooting habits of madrone give it a competitive advantage over Douglas-fir in this area that it might not have if bedrock did not provide the principal water reservoir for summer growth.

Forest Science↗
USGS1998

Reconstructing the spatial pattern of trees from routine stand examination measurements

Reconstruction of the spatial pattern of trees is important for the accurate visual display of unmapped stands. The proposed process for generating the spatial pattern is a nonsimple sequential inhibition process, with the inhibition zone proportionate to the scaled maximum crown width of an open-grown tree of the same species and same diameter at breast height as the subject tree. The results of this coordinate generation procedure are compared with mapped stem data from nine natural stands of Douglas-fir at two ages by the use of a transformed Ripley's K(d) function. The results of this comparison indicate that the proposed method, based on complete tree lists, successfully replicated the spatial patterns of the trees in all nine stands at both ages and over the range of distances examined. On the basis of these findings and the procedure's ability to model effects through time, the nonsimple sequential inhibition process has been chosen to generate tree coordinates in the VIZ4ST computer program for displaying forest stand structure in naturally regenerated young Douglas-fir stands. For. Sci.

Forest Science↗
USGS1984

Effects of the herbicide glyphosate on avian community structure in the Oregon coast range

A study was conducted on vegetative changes induced by the herbicide glyphosate, and the resultant habitat use of birds nesting on two clearcuts in western Oregon. About 23 percent of total plant cover was initially damaged by aerial application of glyphosate. Most measures of vegetation on the treated site decreased relative to the untreated site 1 year after glyphosate application. By 2 years post-spray, vegetation on the treated site had recovered to near pre-spray status. No difference in density of the bird community was evident between treated and untreated sites during all years of study although individual species densities were modified. Several bird species decreased their use of shrub cover, and increased their use of deciduous trees 1 year after treatment. By 2 years post-spray, many species had returned to pre-spray use of most measured habitat components. Results indicated that application of glyphosate can modify the density and habitat use of birds.

Forest Science↗
USGS2006

Optimal regeneration planning for old-growth forest: addressing scientific uncertainty in endangered species recovery through adaptive management

Stochastic and structural uncertainties about forest dynamics present challenges in the management of ephemeral habitat conditions for endangered forest species. Maintaining critical foraging and breeding habitat for the endangered red-cockaded woodpecker (Picoides borealis) requires an uninterrupted supply of old-growth forest. We constructed and optimized a dynamic forest growth model for the Piedmont National Wildlife Refuge (Georgia, USA) with the objective of perpetuating a maximum stream of old-growth forest habitat. Our model accommodates stochastic disturbances and hardwood succession rates, and uncertainty about model structure. We produced a regeneration policy that was indexed by current forest state and by current weight of evidence among alternative model forms. We used adaptive stochastic dynamic programming, which anticipates that model probabilities, as well as forest states, may change through time, with consequent evolution of the optimal decision for any given forest state. In light of considerable uncertainty about forest dynamics, we analyzed a set of competing models incorporating extreme, but plausible, parameter values. Under any of these models, forest silviculture practices currently recommended for the creation of woodpecker habitat are suboptimal. We endorse fully adaptive approaches to the management of endangered species habitats in which predictive modeling, monitoring, and assessment are tightly linked.

Forest Science↗
USGS2011

Estimating riparian understory vegetation cover with beta regression and copula models

Understory vegetation communities are critical components of forest ecosystems. As a result, the importance of modeling understory vegetation characteristics in forested landscapes has become more apparent. Abundance measures such as shrub cover are bounded between 0 and 1, exhibit heteroscedastic error variance, and are often subject to spatial dependence. These distributional features tend to be ignored when shrub cover data are analyzed. The beta distribution has been used successfully to describe the frequency distribution of vegetation cover. Beta regression models ignoring spatial dependence (BR) and accounting for spatial dependence (BRdep) were used to estimate percent shrub cover as a function of topographic conditions and overstory vegetation structure in riparian zones in western Oregon. The BR models showed poor explanatory power (pseudo-R 2 &le; 0.34) but outperformed ordinary least-squares (OLS) and generalized least-squares (GLS) regression models with logit-transformed response in terms of mean square prediction error and absolute bias. We introduce a copula (COP) model that is based on the beta distribution and accounts for spatial dependence. A simulation study was designed to illustrate the effects of incorrectly assuming normality, equal variance, and spatial independence. It showed that BR, BRdep, and COP models provide unbiased parameter estimates, whereas OLS and GLS models result in slightly biased estimates for two of the three parameters. On the basis of the simulation study, 93&ndash;97% of the GLS, BRdep, and COP confidence intervals covered the true parameters, whereas OLS and BR only resulted in 84&ndash;88% coverage, which demonstrated the superiority of GLS, BRdep, and COP over OLS and BR models in providing standard errors for the parameter estimates in the presence of spatial dependence.

Forest Science↗
USGS1998

Impact of alternative regeneration methods on genetic diversity in coastal Douglas-fir

Genetic implications of natural and artificial regeneration following three regeneration methods (group selection, shelterwood, and clearcut) were investigated in coastal Douglas-fir ( Pseudotsuga menziesii var. menziesii [Mirb.] Franco) using genetic markers (17 allozyme loci). In general, harvesting followed by either natural or artificial regeneration resulted in offspring populations little altered from those in the previous generation. Cutting the smallest trees to form shelterwoods, however, resulted in the removal of rare, presumably deleterious, alleles, such that slightly fewer alleles per locus were observed among residual trees (2.76) and natural regeneration (2.75) than found in uncut (control) stands (2.86). Thus, although the shelterwood regime appears quite compatible with gene conservation, it would be best to leave parent trees of a range of sizes in shelterwoods designated as gene conservation reserves, in order to maximize the number of alleles (regardless of current adaptive value) in naturally regenerated offspring. Seedling stocks used for artificial regeneration in clearcut, shelterwood, and group selection stands (7 total) had significantly greater levels of genetic diversity, on average, than found in natural regeneration. This is probably because the seeds used in artificial seedling stocks came from many wild stands and thus, sampled more diversity than found in single populations. For. Sci. 44(3): 390-396.

Forest Science↗
USGS1998

Mixed conifer forest mortality and establishment before and after prescribed fire in Sequoia National Park, California

Pre-and post-burn tree mortality rates, size structure, basal area, and ingrowth were determined for four 1.0 ha mixed conifer forest stands in the Log Creek and Tharp's Creek watersheds of Sequoia National Park. Mean annual mortality between 1986 and 1990 was 0.8% for both watersheds. In the fall of 1990, the Tharp's Creek watershed was treated with a prescribed burn. Between 1991 and 1995, mean annual mortality was 1.4% in the unburned Log Creek watershed and 17.2% in the burned Tharp's Creek watershed. A drought from 1987 to 1992 likely contributed to the mortality increase in the Log Creek watershed. The high mortality in the Tharp's Creek watershed was primarily related to crown scorch from the 1990 fire and was modeled with logistic regression for white fir (Abies concolor [Gord. and Glend.]) and sugar pine (Pinus lambertiana [Dougl.]). From 1989 to 1994, basal area declined an average of 5% per year in the burned Tharp's Creek watershed, compared to average annual increases of less than 1% per year in the unburned Log Creek watershed and in the Tharp's watershed prior to burning. Post-burn size structure was dramatically changed in the Tharp's Creek stands: 75% of trees ???50 cm and 25% of trees >50 cm were killed by the fire.

Forest Science↗
USGS2003

Global forest cover mapping for the United Nations Food and Agriculture Organization forest resources assessment 2000 program

Many countries periodically produce national reports on the status and changes of forest resources, using statistical surveys and spatial mapping of remotely sensed data. At the global level, the Food and Agriculture Organization (FAO) of the United Nations has conducted a Forest Resources Assessment (FRA) program every 10 yr since 1980, producing statistics and analysis that give a global synopsis of forest resources in the world. For the year 2000 of the FRA program (FRA2000), a global forest cover map was produced to provide spatial context to the extensive survey. The forest cover map, produced at the U.S. Geological Survey (USGS) EROS Data Center (EDC), has five classes: closed forest, open or fragmented forest, other wooded land, other land cover, and water. The first two forested classes at the global scale were delineated using combinations of temporal compositing, modified mixture analysis, geographic stratification, and other classification techniques. The remaining three FAO classes were derived primarily from the USGS global land cover characteristics database (Loveland et al. 1999). Validated on the basis of existing reference data sets, the map is estimated to be 77% accurate for the first four classes (no reference data were available for water), and 86% accurate for the forest and nonforest classification. The final map will be published as an insert to the FAO FRA2000 report.

Forest Science↗
USGS2005

Mismatch between herbivore behavior and demographics contributes to scale-dependence of host susceptibility in two pine species

The impacts on forests of tree-killing bark beetles can depend on the species composition of potential host trees. Host susceptibility might be an intrinsic property of tree species, or it might depend on spatial patterning of alternative host species. We compared the susceptibility of loblolly pine (Pinus taeda) and Virginia pine (P. virginiana) to southern pine beetle (Dendroctonus frontalis) at two hierarchical levels of geographic scale: within beetle infestations in heterospecific stands (extent ranging from 0.28 to 0.65 ha), and across a forest landscape (extent 72,500 ha) that was dominated by monospecific stands. In the former, beetles preferentially attacked Virginia pine (tree mortality = 65-100% in Virginia pine versus 0-66% in loblolly pine), but in the latter, loblolly stands were more susceptible than Virginia stands. This hierarchical transition in host susceptibility was predicted from knowledge of (1) a behavioral preference of beetles for attacking loblolly versus Virginia pine, (2) a negative correlation between preference and performance, and (3) a mismatch in the domain of scale between demographics and host selection by individuals. There is value for forest management in understanding the processes that can produce hierarchical transitions in ecological patterns. Copyright ?? 2005 by the Society of American Foresters.

Forest Science↗
USGS2006

Status of soil acidification in North America

Forest soil acidification and depletion of nutrient cations have been reported for several forested regions in North America, predominantly in the eastern United States, including the northeast and in the central Appalachians, but also in parts of southeastern Canada and the southern U.S. Continuing regional inputs of nitrogen and sulfur are of concern because of leaching of base cations, increased availability of soil Al, and the accumulation and ultimate transmission of acidity from forest soils to streams. Losses of calcium from forest soils and forested watersheds have now been documented as a sensitive early indicator and a functionally significant response to acid deposition for a wide range of forest soils in North America. For red spruce, a clear link has been established between acidic deposition, alterations in calcium and aluminum supplies and increased sensitivity to winter injury. Cation depletion appears to contribute to sugar maple decline on some soils, specifically the high mortality rates observed in northern Pennsylvania over the last decade. While responses to liming have not been systematically examined in North America, in a study in Pennsylvania, restoring basic cations through liming increased basal area growth of sugar maple and levels of calcium and magnesium in soil and foliage. In the San Bernardino Mountains in southern California near the west coast, the pH of the A horizon has declined by at least 2 pH units (to pH 4.0-4.3) over the past 30 years, with no detrimental effects on bole growth; presumably, because of the Mediterranean climate, base cation pools are still high and not limiting for plant growth.

Journal of Forest Science↗
USGS2008

Stand-level forest structure and avian habitat: Scale dependencies in predicting occurrence in a heterogeneous forest

We explored the role of stand-level forest structure and spatial extent of forest sampling in models of avian occurrence in northern hardwood-conifer forests for two species: black-throated blue warbler (Dendroica caerulescens) and ovenbird (Seiurus aurocapillus). We estimated site occupancy from point counts at 20 sites and characterized the forest structure at these sites at three spatial extents (0.2, 3.0, and 12.0 ha). Weight of evidence was greatest for habitat models using forest stand structure at the 12.0-ha extent and diminished only slightly at the 3.0-ha extent, a scale that was slightly larger than the average territory size of both species. Habitat models characterized at the 0.2-ha extent had low support, yet are the closest in design to those used in many of the habitat studies we reviewed. These results suggest that the role of stand-level vegetation may have been underestimated in the past, which will be of interest to land managers who use habitat models to assess the suitability of habitat for species of concern. Copyright ?? 2008 by the Society of American Foresters.

Forest Science↗
USGS2008

δ 15 N patterns of Douglas-fir and red alder riparian forests in the Oregon Coast Range

We used naturally occurring stable isotopes of N to compare N dynamics in near-stream and upslope environments along riparian catenas in N-fixing red alder (Alnus rubra) and Douglas-fir (Pseudotsuga menziesii) forests in the Coast Range of western Oregon. Based on the existing literature, we expected soil δ 15 N to be enriched closer to streams owing to inputs of isotopically heavy, marine-derived N by spawning salmon, higher rates of denitrification near the stream, or both. However, it has been unclear what effect red alder might have on soil δ 15 N patterns near streams. We found a consistent −1‰ δ 15 N signature in red alder foliage, and δ 15 N of total N in soils under red alder averaged 2.2‰ along sampling transects extending 20 m upslope from the stream. Surprisingly, δ 15 N of total N in soil under Douglas-fir was progressively depleted nearer to streams, opposite from the pattern expected from N losses by denitrification or N inputs from anadromous salmon. Instead, δ 15 N of total N in soil under Douglas-fir converged toward soil δ 15 N values typical of red alder sites. We consider that the historic presence of red alder may have contributed a legacy of lower soil δ 15 N nearer to streams on sites that are currently dominated by young Douglas-fir forest.

Oregon↗
USGS1989

Disturbance-mediated accelerated succession in two Michigan forest types

In northern lower Michigan, logging accelerated sugar maple ( Acer saccharum ) dominance in a northern white cedar ( Thuja occidentals ) community, and clear-cutting and burning quickly converted certain sites dominated by mature jack pine ( Pinus banksiana ) to early-succesional hardwoods, including Prunus, Populus , and Quercus . In both forest types the succeeding hardwoods should continue to increase in the future at the expense of the pioneer conifer species. In the cedar example, sugar maple was also increasing a an undisturbed, old-growth stand, but at a much reduced rate than in the logged stand. Traditionally, disturbance was through to set back succession to some earlier stage. However, out study sites and at least several other North American forest communities exhibited accelerated succession following a wide range of disturbances, including logging fire, ice storms, wind-throw, disease, insect attack, and herbicide spraying.

Michigan↗
USGS2019

Corrigendum to “A comprehensive analysis of interseasonal and interannual energy and water balance dynamics in semiarid shrubland and forest ecosystems” [Sci. Total Environ. 651 (2019) 381–398]

The authors regret the omission of an author, funding sources, and key support staff. The omitted author and their affiliation is: Matthew J Germino US Geological Survey, Forest and Rangeland Ecosystem Science Center, Boise ID 83706. The correct citation should be: Valayamkunnath, P., Sridhar, V., Zhao, W. Allen, R.G., and Germino, M.J., 2019. A comprehensive analysis of interseasonal and interannual energy and water balance dynamics in semiarid shrubland and forest ecosystems. Science of The Total Environment, 651, 381–398. Additions to the Acknowledgements include: Funding was provided by the U.S. Bureau of Land Management and US Department of Agriculture National Research Initiative. Jeremy Greth, Clarence Robinson, Ricardo Trezza, Jeppe Kjaersgaard, and many other field technicians from Idaho State University and Boise State University assisted in setting up the experiment. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Science of the Total Environment↗
USGS2013

Oak woodlands and forests fire consortium: A regional view of fire science sharing

The Joint Fire Science Program established 14 regional fire science knowledge exchange consortia to improve the delivery of fire science information and communication among fire managers and researchers. Consortia were developed regionally to ensure that fire science information is tailored to meet regional needs. In this paper, emphasis was placed on the Oak Woodlands and Forests Fire Consortium to provide an inside view of how one regional consortium is organized and its experiences in sharing fire science through various social media, conference, and workshop-based fire science events.

Conference Paper↗