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Seeing past the green: Structure, composition, and biomass differences in high graded and silviculture-managed forests of similar stand density
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Forests of the eastern United States (US) mostly comprise a mix of stands managed following silvicultural
principles and stands managed with exploitative timber harvesting practices. These stands can have similar stand
densities (e.g., basal area per hectare) but vary vastly in structure, composition, and biomass and carbon storage.
High grading, a prevalent exploitative timber harvesting practice in the eastern US, is of particular concern
because it can negatively affect future forest health and productivity. This study quantifies differences in forest
structure, composition, and biomass and carbon storage between high graded stands and stands that received a
seed/establishment cut of a uniform shelterwood regeneration sequence treatment, which is a comparable and
well-established silvicultural method used to regenerate mixed-oak forests. It focuses on mixed-oak forests
(mixed-Quercus), where the effects of high grading have been understudied, and uses a sample with broader
spatial coverage than previous studies. The sample comprised nine stands that were known to have been high
graded 8–15 years ago and nine stands that received the seed/establishment cut of a uniform shelterwood
regeneration sequence. Stand were systematically sampled using fixed-area plots. Field measurements were
collected and used to calculate metrics describing forest structure and function. The structure of high graded
stands was characterized by a higher proportion of trees with poor health and/or form compared to shelterwood
stands, with 18.3 % less acceptable growing stock and trees with lower crown compaction. Diameter distributions
of high graded stands were characterized by numerous small trees and few large-diameter trees. Spatial
variability of overstory trees was contingent on the tree size range evaluated, with a larger variability of
sawtimber-sized trees (trees ≥ 29.2 cm in diameter at breast height) in high graded stands. High graded stands
also had 2.2 times fewer oak trees (Quercus spp.) in the overstory canopy, 17,897 fewer seedlings per hectare
(ha), and 45 Mg/ha less biomass than shelterwood stands. These results indicate that high grading generally
degrades mixed-oak forests and impairs their long-term capacity to supply vital ecosystem services such as
habitat for specific wildlife species, carbon storage, and high-quality wood products.
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WLFW Outcomes: Funded Research
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Best Management Practices for Golden-winged Warbler Habitat in Deciduous Forests of the Appalachians
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This is a supplemental document that provides information on managing deciduous forests in the Appalachians to develop and restore habitat for Golden-winged Warblers. This guide should be used in conjunction with the Best Management Practices for Golden-winged Warbler Habitats in the Appalachian Region, which includes general information that applies to all habitat types in the Appalachian region.
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Golden-Winged Warbler Appalachians Fact Sheets
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Best Management Practices for Golden-winged Warbler Habitats in the Appalachian Region: A Guide for Land Managers and Landowners
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This guide is intended to provide land managers and landowners with regional, habitat-specific strategies and techniques to begin developing and restoring habitat for Golden-winged Warblers. This document includes general information that applies to all habitat types in the Appalachian region and should be used along with supplemental documents dedicated to the management of specific regional habitat types (deciduous forests, minelands, abandoned farmlands, grazed forestland/montane pastures, utility rights-of-way, forest and shrub wetlands) most important to Golden-winged Warblers.
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Golden-Winged Warbler Appalachians Fact Sheets
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Bhuta, Arvind
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Predicting a change in the order of spring phenology in temperate forests
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The rise in spring temperatures over the past half-century has led to advances in the phenology of many nontropical plants and animals. As species and populations differ in their phenological responses to temperature, an increase in temperatures has the potential to alter timing-dependent species interactions. One species-interaction that may be affected is the competition for light in deciduous forests, where early vernal species have a narrow window of opportunity for growth before late spring species cast shade. Here we consider the Marsham phenology time series of first leafing dates of thirteen tree species and flowering dates of one ground flora species, which spans two centuries. The exceptional length of this time series permits a rare comparison of the statistical support for parameter-rich regression and mechanistic thermal sensitivity phenology models. While mechanistic models perform best in the majority of cases, both they and the regression models provide remarkably consistent insights into the relative sensitivity of each species to forcing and chilling effects. All species are sensitive to spring forcing, but we also find that vernal and
northern European species are responsive to cold temperatures in the previous autumn. Whether this sensitivity reflects a chilling requirement or a delaying of dormancy remains to be tested. We then apply the models to projected future temperature data under a fossil fuel intensive emissions scenario and predict that while some species will advance substantially others will advance by less and may even be delayed due to a rise in autumn and winter temperatures. Considering the projected responses of all fourteen species, we anticipate a change in the order of spring events, which may lead to changes in competitive advantage for light with potential implications for the composition of temperate forests.
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Changes in the Asian monsoon climate during 1700 –1850 induced by preindustrial cultivation
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Preindustrial changes in the Asian summer monsoon climate from the 1700s to the 1850s were estimated with an atmospheric general circulation model (AGCM) using historical global land cover/use change data reconstructed for the last 300 years. Extended cultivation resulted in a decrease in monsoon rainfall over the Indian subcontinent and southeastern China and an associated weakening of the Asian summer monsoon circulation. The precipitation decrease in India was marked and was consistent with the observational changes derived from examining the Himalayan ice cores for the concurrent period. Between the 1700s and the 1850s, the anthropogenic increases in greenhouse gases and aerosols were still minor; also, no long-term trends in natural climate variations, such as those caused by the ocean, solar activity, or volcanoes, were reported. Thus, we propose that the land cover/ use change was the major source of disturbances to the climate during that period. This report will set forward quantitative ex-amination of the actual impacts of land cover/use changes on Asian monsoons, relative to the impact of greenhouse gases and aerosols, viewed in the context of global warming on the interannual, decadal, and centennial time scales.
atmospheric water balance climate change historical land-cover change monsoon rainfall
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Clone history shapes Populus drought responses
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Just as animal monozygotic twins can experience different environmental conditions by being reared apart, individual genetically identical trees of the genus Populus can also be exposed to contrasting environmental conditions by being grown in different locations. As such, clonally propagated Populus trees provide an opportunity to interrogate the impact of individual environmental history on current response to environmental stimuli. To test the hypothesis that current responses to an environmental stimulus, drought, are contingent on environmental history, the transcriptome- level drought responses of three economically important hybrid genotypes—DN34 (Populus deltoides × Populus nigra), Walker [P. deltoides var. occidentalis × (Populus laurifolia × P. nigra)], and Okanese [Walker × (P. laurifolia × P. nigra)]—derived from two different locations were compared. Strikingly, differences in transcript abundance patterns in response to drought were based on differences in geographic origin of clones for two of the three genotypes. This observation was most pronounced for the genotypes with the longest time since establishment and last common propagation. Differences in genome-wide DNA methylation paralleled the transcriptome level trends, whereby the clones with the most divergent transcriptomes and clone history had the most marked differences in the extent of total DNA methylation, suggesting an epigenomic basis for the clone history-dependent transcriptome divergence. The data provide insights into the interplay between genotype and environment in the ecologically and economically important Populus genus, with implications for the industrial application of Populus trees and the evolution and persistence of these important tree species and their associated hybrids.
epigenetics | forest trees | poplar
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