WLFW Outcomes: Funded Research
Poster Presentation: Seeing Past the Green: Quantifying the Characteristics of High-graded Forests
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Seeing past the green: Structure, composition, and biomass differences in high graded and silviculture-managed forests of similar stand density
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.
Decision Support Tools to Inform the Rehabilitation and Management of High Graded Forests
Abstract Numerous forests in the eastern United States have been degraded due to past exploitative timber harvesting known as high grading. High graded forest stands may not improve without active re- habilitation and may require targeted silvicultural treatments. This study focuses on high graded mixed-oak (mixed-Quercus spp.) stands and aims to develop a model that can identify past high grading and to determine modifications that may improve forest management recommendations provided by the prominent decision support tool, SILVAH. We present a model that uses standard forest inventory measurements and does not require knowledge of preharvest stand conditions to predict with moderate to high accuracy whether a stand was high graded, which could be par- ticularly useful for nonindustrial private forests. Results indicate that modifications to SILVAH may be necessary to improve its utility for prescribing silvicultural treatments in high graded stands. Study Implications: High graded forest stands are often not readily apparent and likely require specific forest management practices. We present a tool that uses standard forest inventory meas- urements to predict past high grading, which can be used to inform and prioritize forest manage- ment decisions. We also present suggested modifications to the prominent decision support tool, SILVAH, that may improve its ability to prescribe optimal silvicultural treatments for high graded stands. Results from this study provide forestry professionals/landowners working in the mixed- oak forests of the northeastern United States with tools to inform forest management decisions that aim to return degraded stands to healthier and more productive states.
Do Review Papers on Bird–Vegetation Relationships Provide Actionable Information to Forest Managers in the Eastern United States?
Abstract Forest management planning requires the specification of measurable objectives as desired future conditions at spatial extents ranging from stands to landscapes and temporal extents ranging from a single growing season to several centuries. Effective implementation of forest management requires understanding current conditions and constraints well enough to apply the appropriate silvicultural strategies to produce desired future conditions, often for multiple objectives, at varying spatial and temporal extents. We administered an online survey to forest managers in the eastern US to better understand how wildlife scientists could best provide information to help meet wildlife-related habitat objectives. We then examined more than 1000 review papers on bird–vegetation relationships in the eastern US compiled during a systematic review of the primary literature to see how well this evidence-base meets the information needs of forest managers. We identified two main areas where wildlife scientists could increase the relevance and applicability of their research. First, forest managers want descriptions of wildlife species–vegetation relationships using the operational metrics of forest management (forest type, tree species composition, basal area, tree density, stocking rates, etc.) summarized at the operational spatial units of forest management (stands, compartments, and forests). Second, forest managers want information about how to provide wildlife habitats for many different species with varied habitat needs across temporal extents related to the ecological processes of succession after harvest or natural disturbance (1–2 decades) or even longer periods of stand development. We provide examples of review papers that meet these information needs of forest managers and topic-specific bibliographies of additional review papers that may contain actionable information for foresters who wish to meet wildlife management objectives. We suggest that wildlife scientists become more familiar with the extensive grey literature on forest bird–vegetation relationships and forest management that is available in natural resource management agency reports. We also suggest that wildlife scientists could reconsider everything from the questions they ask, the metrics they report on, and the way they allocate samples in time and space, to provide more relevant and actionable information to forest managers. View Full-Text Keywords: forestry; silviculture; forest wildlife–habitat relationships; evidence-based practice; implementation gap; research relevance; synthesis; knowledge exchange; science–practice
Regional abundance and local breeding productivity explain occupancy of restored habitats in a migratory songbird
Ecological restoration is a key tool in offsetting habitat loss that threatens biodiversity worldwide, but few projects are rigorously evaluated to determine if conservation objectives are achieved. We tested whether restoration outcomes for an imperiled bird, the Golden-winged Warbler (Vermivora chrysoptera; GWWA) met the assumptions of the ‘Field of Dreams’ hypothesis or whether local and regional population dynamics impacted restoration success. From 2015 to 18, we surveyed 514 points located in recently restored successional habitats. We used new- and published data on the survival of 341 nests and 258 fledglings to estimate GWWA breeding productivity. Occupancy and colonization of restored habitats were significantly higher in our Western Study Region (Minnesota and Wisconsin) than our Eastern Study Region (Maryland, Pennsylvania, and New Jersey), a pattern that mirrored broader regional population trends. At local scales, productivity was high in Eastern Pennsylvania (> 3 independent juveniles/pair/year) but low in Central Pennsylvania (1 juvenile/pair/year) while both Western and Central Minnesota hosted intermediate productivity (between 1 and 2 juveniles/pair/ year). Productivity and occupancy covaried locally in the Eastern Study Region, while occupancy was high in the Western Study Region, despite intermediate productivity. These differences have profound implications for restoration outcomes, as GWWA possessed robust capacity to respond to habitat restoration in both regions, but this capacity was conditional upon local productivity where the species is rare. Our findings suggest that, even when restoration efforts are focused on a single species and use comparable prescriptions, interactions among processes governing habitat selection, settlement, and productivity can yield variable restoration outcomes.
Multiscale drivers of restoration outcomes for an imperiled songbird
Habitat restoration is a cornerstone of conservation, particularly for habitat-limited species. However, restoration efforts are seldom rigorously monitored at meaningful spatial scales. Poor understanding of how species respond to habitat restoration programs limits conservation efficacy for habitat-restricted species like the Golden-winged Warbler (Vermivora chrysoptera, GWWA). We provide one of the first concerted assessments of a national conservation program aimed at restoring songbird habitat across its breeding range. We studied GWWA response to forest habitat restoration across two broad regions with opposing population trajectories and assessed factors driving species use of restored habitats across multiple spatial scales. From 2015 to 2017, we conducted 1,145 (n = 457 locations) and 519 point counts (n = 215 locations) across the Appalachian Mountains and Great Lakes (respectively) within restored habitats. Warbler abundance within restored habitats across the Great Lakes varied with latitude, longitude, elevation, forest type, and number of growing seasons. In the Appalachian Mountains, occupancy ( ^ ψ) varied with longitude, elevation, forest type, and number of growing seasons. Detections were restricted to areas within close proximity to population centers (usually <24 km) in the Appalachian Mountains, where GWWAs are rare ( ^ ψ= 0.22, 95% confidence interval [CI]: 0.20–0.25), but not in the Great Lakes, whereGWWAs remain common ( ^ ψ= 0.87, 95% CI: 0.84–0.90). Our study suggests that, even when best management practices are carefully implemented, restoration outcomes vary within/across regions and with multiscale habitat attributes. Although assessments of concerted habitat restoration efforts remain uncommon, our study demonstrates the value of monitoring data in the adaptive management process for imperiled species.
