Academic literature on the topic 'Deciduous forest'

Nontimber forest products (NTFPs) play an important role in the lives of people who rely on forests. An absence of data on the size of harvests, their location, and the economic value of NTFPs prevents effective management and full utilization by all stakeholder groups. We set out to measure one important NTFP sector -- the medicinal plant trade in the diverse deciduous forests of the eastern United States, by surveying licensed buyers of ginseng (Panax quinquefolius) in 15 states about purchasing of other untracked species. To combat potential coverage and non-response bias we created a place-based model that predicted the probability of purchasing non-ginseng medicinals based on buyer location and used this to build more robust estimates. This viable method for estimating NTFP output is a replicable system that can be applied in other regions and for other products. We reviewed the literature and hypothesized biophysical and socioeconomic factors that might contribute to the prevalence of non-ginseng purchasing, and tested them on the respondents using multinomial logistic regression. The significant variables were used in two-step cluster analysis to categorize respondents and non-respondents in high or low production areas. Volume was assigned to non-respondents based on respondent behavior within each cluster. Both were then summed to estimate total output. The results depict trade volume and prices paid to harvesters for 11 medicinal NTFP species. There was significant variation between products. Two species, black cohosh (Actaea racemosa) and goldenseal (Hydrastis canadensis), accounted for 72 percent of trade volume and 77 percent of the value paid to harvesters. The total first-order value for all species estimated was 4.3 million $USD. The discrepancy between point-of-sale and retail value implies room for increasing value for all stakeholders at the base of the supply chain. Harvests for most species were concentrated in the central Appalachian coalfields. We also sought to understand what motivated or deterred participation by conducting qualitative interviews with buyers and other stakeholders. Buyers were interested in knowing the size and value of the trade, but had concerns about losing access to the resource, which was rooted in past experience with land managers and policy-makers, and conflicting discourse between stakeholders about the state of the trade and of wild populations. Many institutional deliverables are not well matched with the realities or priorities of the traditional trade. We describe potential avenues for collaboration and reciprocity, including providing market research and certifying or providing technical support for sustainably wild harvested material in addition to ongoing support for cultivation.<br>PHD

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2002.<br>Abstract inserted. Appendix includes reprints of a published paper and three manuscripts, each co-authored with a different author. Includes bibliographical references. Also partially issued electronically via World Wide Web in PDF format; online version lacks appendix.

A persistent and reliable future terrestrial carbon (C) sink will depend on how stable forest production is under more variable climate conditions. We examined how age, forest structure, and disturbance history relate to the interannual variability of above-ground wood net primary production (NPPw). Our site in northern Michigan spans two experimental forest chronosequences and three late successional stands; the chronosequences have distinct disturbance histories, originating following either clear cut harvesting (“Cut Only”) or clear cut harvesting and fire (“Cut and Burn”), and range from 21 to 108 years old. Annual NPPw was estimated using dendrochronology and site specific allometric equations. We used a portable canopy LiDAR (PCL) system to derive canopy rugosity, a measure of the variability and heterogeneity of vertical and horizontal leaf arrangement, to quantify plot level canopy complexity. Counter to our hypothesis, we found that NPPw stability was greatest in the most frequently disturbed, Cut and Burn stands and lowest in less recently disturbed, late successional forest communities. Opposing trends in chronosequence interannual variation of NPPw indicated that stand age and canopy complexity are not consistently related to production stability. Furthermore, sub-canopy leaf trait properties and breadth were not, as hypothesized, correlated with canopy complexity or NPPw stability. Our mixed findings suggest that multiple factors, including stand age and disturbance history, interact to influence NPPw stability, but also highlight an unexpected dichotomy in which disturbance legacies at our site negatively impact the long-term trajectory of annual forest NPPw, but enhance its interannual stability.

This thesis investigates variations in solar irradiance incident upon sloping surfaces under deciduous forest in winter. A model is presented for prediction of solar irradiance at the surface which accounts for slope inclination and orientation, surrounding topography, isotropic absorption of solar radiation by the crown space, and shadows cast by the stem space.<br>Field data from two sites of different slope and aspect attest to the validity of the model; errors, based on 20-minute averages of instantaneous values, are 15.5% (RMSE) and $-$1.9% (MBE). Error is partially due to reliance upon global radiation measurements above canopy at a different site (partially cloudy conditions) and sampling error (sunny sky conditions). The variability of solar irradiance at the surface, and in the error of predicted values, is found to vary with sky condition, solar zenith and incidence angles, and slope orientation. However, integration to hourly and/or daily time periods improves model performance significantly.