Treesearch

Both aggregative and disaggregative strategies were used to develop additive nonlinear biomass equations for slash pine (Pinus elliottii Engelm. var. elliottii) trees in the southeastern United States. In the aggregative approach, the total tree biomass equation was specified by aggregating the expectations of component biomass models, and their parameters were estimated by jointly fitting all component and total biomass equations using weighted nonlinear seemingly unrelated regression (NSUR) (SUR1) or by jointly fitting component biomass equations using weighted NSUR (SUR2). In an...

Family forest owners in the United States have underscored the need for forest insect pest (FIP) information, and numerous Extension programs have been developed to meet pest information needs. We developed the Pest Awareness Index to illustrate the heterogeneity of familiarity, knowledge, and experience regarding three FIPs (hemlock woolly adelgid, emerald ash borer, Asian long-horned beetle) in four New England states. Using mail survey data of family forest owners, we calculated an index from three components and provided comparisons based on region and actual insect presence. The...

Models are pivotal for assessing future forest dynamics under the impacts of changing climate and management practices, incorporating representations of tree growth, mortality, and regeneration. Quantitative studies on the importance of mortality submodels are scarce. We evaluated 15 dynamic vegetation models (DVMs) regarding their sensitivity to different formulations of tree mortality under different degrees of climate change. The set of models comprised eight DVMs at the stand scale, three at the landscape scale, and four typically applied at the continental to global scale. Some...

Although a rich history of scholarship exists on the attitudes, past behaviors, and behavioral intentions of family forest owners, little is known about how these social factors change over time. Furthermore, linking behavioral intentions with actual behaviors of family forest owners will require a longitudinal design that re-measures behaviors of the same respondents over time to match with earlier surveys of intention to behavior. Previous attempts to measure behavioral and attitudinal change over time have been largely opportunistic and have not followed a true longitudinal study...

Bioenergy cropping systems have the potential to supply plant biomass as lignocellulosic feedstock for biofuels and bioproducts that will reduce reliance on fossil energy. Identifying the effects of alternative bioenergy cropping systems on soil carbon (C) is necessary to assess the sustainability of renewable fuels. We measured the response of soil organic carbon (SOC) pools to four bioenergy cropping systems using soils collected at the establishment of the field trials and after five years in two soils of contrasting texture: a fine-textured silt loam (Mollisol) in south central...

Forest ecosystems contribute substantially to carbon (C) storage. The dynamics of litter decomposition, translocation and stabilization into soil layers are essential processes in the functioning of forest ecosystems, as these processes control the cycling of soil organic matter and the accumulation and release of C to the atmosphere. Therefore, the spatial distribution of litter and soil C stocks are important in greenhouse gas estimation and reporting and inform land management decisions, policy, and climate change mitigation strategies. Here we explored the effects of spatial aggregation...

We examined the effects of foliar supplementation of different nitrogen sources (urea, Nitamin, NH4NO3, and arginine) to study their efficacy as fertilizers for growth of two clonally propagated shrub willow cultivars; namely, 'Fish Creek' (Salix purpurea L.) and 'Preble' (Salix viminalis L. × (Salix sachalinensis F. Schmidt × Salix miyabeana Seemen)). Our objectives were to determine (i) if foliar nitrogen application is an effective method of fertilization for the two shrub willows and (ii) if different nitrogen sources are metabolized similarly by the plants. The analyses involved...

In the northwestern Himalayan mountains of India, the hypogeous sequestrate fungus Trappeindia himalayensis is harvested from forests dominated by the ectomycorrhizal tree Cedrus deodara (Himalayan cedar). This truffle has basidiospores that are ornamented with raised reticulation. The original description of Trappeindia himalayensis suggested that the gleba of this species is similar to young specimens of Scleroderma (Boletales), whereas its basidiospores are ornamented with raised reticulation, suggesting a morphological affinity to Leucogaster (Russulales) or Strobilomyces (Boletales)....

The collective impacts of fire exclusion polices, mountain pine beetle (Dendroctonus ponderosae Hopkins) outbreaks, and white pine blister rust (Cronartium ribicola J.C. Fisch) infections have resulted in a rapid decline of whitebark pine (Pinus albicaulis Engelm.) forests in western North America over the last several decades (Arno 1986, Kendall and Keane 2001, Goeking and Izlar 2018). Especially distressing are the projected declines in these iconic forests because of future changes in climate (Warwell et al. 2007, Chang et al. 2014). Future warmer and drier climates could result in...

The populations of the Caucasian pit viper are declining and face genetic threats because of habitat fragmentation. Landscape genetics facilitates effective connectivity conservation actions by providing methods to predict factors affecting gene flow. Objectives We described the genetic diversity and structure of Caucasian pit viper populations in Iran. We also adopted an individual-based landscape genetics approach to determine the effects of landscape features on gene flow across the species’ range. Methods We evaluated the degree of genetic structuring using spatial and non-spatial...