Treesearch

The original crown-rise model estimates the average height of a crown-base in an even-aged mono-species stand of trees. We have elaborated this model to reduce bias and prediction error, and to also provide crown-base estimates for individual trees. Results for the latter agree with a theory of branch death based on resource availability and allocation.We use the improved model to estimate the growth and stem-profile development of a mean-tree in an even-aged stand of loblolly pine. Predictions show good agreement with data from a loblolly pine spacing trial.

Two mycorrhizal taxa are described: Lactarius rubidus from the west coast and Leccinellum quercophilum from eastern North America. Lactarius rubidus is a new combination for Lactarius fragilis var. rubidus, here validated after a previous invalid publication. Leccinellum quercophilum is a new species. Detailed macro- and microscopic descriptions, ITS and LSU sequences, illustrations of microscopic features, and plates are presented for each species; a type study of Lactarius fragilis var. rubidus is also provided.

Mean sensitivity (ζ) continues to be used in dendrochronology despite a literature that shows it to be of questionable value in describing the properties of a time series. We simulate first-order autoregressive models with known parameters and show that ζ is a function of variance and autocorrelation of a time series. We then use 500 random tree-ring data sets with unknown parameters and show that ζ is at best equivalent to the standard deviation of a time series in cases without high autocorrelation and is an inefficient estimator of the coefficient of variation. It is hard to justify the...

Researchers and natural resource managers need predictions of how multiple global changes (e.g., climate change, rising levels of air pollutants, exotic invasions) will affect landscape composition and ecosystem function. Ecological predictive models used for this purpose are constructed using either a mechanistic (process-based) or a phenomenological (empirical) approach, or combination. Given the accelerating pace of global changes, it is becoming increasingly difficult to trust future projections made by phenomenological models estimated under past conditions. Using forest landscape...

Some extensively used wood adhesives, such as pMDI (polymeric methylene diphenyl diisocyanate) and PF (phenol formaldehyde) have shown excellent adhesion properties with wood. However, distinguishing whether the strength is due to physical bonds (i.e., van der Waals, London, or hydrogen bond forces) or covalent bonds between the adherend and the adhesive is not fully understood. Previous studies, where pMDI model compounds were reacted with wood, showed that carbamate (urethane) formation with wood polymers is only possible when: 1. the number of moles of isocyanate is significantly higher...

American Beech (Fagus grandifolia Ehrh.) root sprouts often form dense understories that interfere with tree reproduction throughout much of the eastern hardwood region. The cut-stump treatment, whereby herbicide is applied to the stump within a few hours after a larger beech is felled, has been shown to mitigate the interference problem by eliminating beech stems attached to the parent tree's root system. Forest managers are often reluctant to prescribe this treatment because the short time interval between felling the tree and applying herbicide requires the applicator to work in...

Implementation of urban sustainability policies often requires collaborations between organizations across sectors. Indeed, it is commonly agreed that governance by environmental networks is preferred to individual organizations acting alone. Yet research shows that network structures vary widely, and that these variations can impact network effectiveness. However, large scale studies of environmental net-work structure and outcomes are rare. Little research exists that evaluates whether local environmental conditions impact network structure, and whether the structure, or even the...

There is growing scientific interest, practical need, and substantial support for understanding urban and urbanising areas in terms of their long-term social and ecological trajectories: past, present, and future. Long-term social-ecological research (LTSER) platforms and programmes in urban areas are needed to meet these interests and needs. We describe our experiences as a point of reference for other ecologists and social scientists embarking on or consolidating LTSER research in hopes of sharing what we have learned and stimulating comparisons and collaborations in urban, agricultural,...

Urban Tree Canopy (UTC) Prioritizations can be both a set of geographic analysis tools and a planning process for collaborative decision-making. In this paper, we describe how UTC Prioritizations can be used as a planning process to provide decision support to multiple government agencies, civic groups and private businesses to aid in reaching a canopy target. Linkages to broader City-scale sustainability plans are explored. This article represents an extension and update to the UTC Canopy Goal Setting Guide by Raciti et al (2006). We conclude with recommendations for a market-like...

Global climate change is among the greatest threats confronting both human and natural systems (IPCC, 2007). A substantial component of greenhouse gas (GHG) emissions is from energy production, generated via the burning of fossil fuels, especially coal, natural gas and refined petroleum. Given that reduction in global energy consumption is unlikely over the next century or so, renewable energy generation has been proposed as a low-carbon alternative to limit GHG emissions. Consequently, many national and regional governments have set targets for renewable energy manufacture and use (e.g....