Treesearch

This paper describes the use of field surveys, biometric information for urban tree species and remote sensing to quantify and map carbon (C) storage, sequestration and avoided emissions from energy savings. Its primary contribution is methodological; the derivation and application of urban tree canopy (UTC) based transfer functions (t C ha-1 UTC). Findings for Los Angeles and Sacramento illustrate the complex role of regional and local determinants. Although average tree density and size were substantially greater in Los Angeles, the mean C storage density (8.15 t ha-1) was 53 percent of...

The Rothermel surface fire spread model includes a wind speed limit, above which predicted rate of spread is constant. Complete derivation of the wind limit as a function of reaction intensity is given, along with an alternate result based on a changed assumption. Evidence indicates that both the original and the revised wind limits are too restrictive. Wind limit is based in part on data collected on the 7 February 1967 Tasmanian grassland fires. A reanalysis of the data indicates that these fires might not have been spreading in fully cured continuous grasslands, as assumed. In addition,...

In this article we develop a simulation model to evaluate the economic efficiency of fuel treatments and apply it to two sagebrush ecosystems in the Great Basin of the western United States: the Wyoming Sagebrush Steppe and Mountain Big Sagebrush ecosystems. These ecosystems face the two most prominent concerns in sagebrush ecosystems relative to wildfire: annual grass invasion and native conifer expansion. Our model simulates long-run wildfire suppression costs with and without fuel treatments explicitly incorporating ecological dynamics, stochastic wildfire, uncertain fuel treatment...

A genecological approach was used to explore genetic variation in adaptive traits in Pseudoroegneria spicata, a key restoration grass, in the intermountain western United States. Common garden experiments were established at three contrasting sites with seedlings from two maternal parents from each of 114 populations along with five commercial releases commonly used in restoration. Traits associated with size, flowering phenology, and leaf width varied considerably among populations and were moderately correlated with the climates of the seed sources. Pseudoroegneria spicata populations...

We examined small, fishless headwater streams to determine whether transport of macroinvertebrates into the littoral zone of an oligotrophic lake augmented food availability for Cottus asper, an abundant predatory fish in our study system. We sampled fish and macroinvertebrates during the recruitment and growth season of 2 years, either monthly (2004) or bi-monthly (2005), to observe whether stream inputs increased prey availability and whether variation in total macroinvertebrate biomass was tracked by fish. Our results suggest that the effect of fishless headwater streams on downstream...

Factors influencing invasive taxa may change during the course of an invasion. For example, intraspecific competition is predicted to be more important in areas with older stands of dense monospecific invaders than at the margins of an invaded range. We evaluated evolution in response to predicted changes in competition by comparing the intraspecific competitive ability of North American populations of Japanese honeysuckle (Lonicera japonica) from areas established 100-150 yr ago, which make up the core of the invaded range, to populations from the northern range margin, established in the...

We develop projections of participation and use for 17 nature-based outdoor recreation activities through 2060 for the Northern United States. Similar to the 2010 Resources Planning Act (RPA) assessment, this report develops recreation projections under futures wherein population growth, socioeconomic conditions, land use changes, and climate are allowed to change over time. Findings indicate that outdoor recreation will likely remain a key part of the region's future social and economic fabric. The number of participants in 14 of the 17 recreation activities is projected to increase over...

The inventory and monitoring of coarse woody debris (CWD) carbon (C) stocks is an essential component of any comprehensive National Greenhouse Gas Inventory (NGHGI). Due to the expense and difficulty associated with conducting field inventories of CWD pools, CWD C stocks are often modeled as a function of more commonly measured stand attributes such as live tree C density. In order to assess potential benefits of adopting a field-based inventory of CWD C stocks in lieu of the current model-based approach, a national inventory of downed dead wood C across the U.S. was compared to estimates...

Individual-tree measurements have been collected periodically on sites established in Kentucky, New York, Ohio, and Pennsylvania to investigate the effects of thinning on the growth and yield of valuable hardwood species. These plots were installed between 1959 and 1985. The long-term characteristics of this data set of 47,853 trees allowed us to investigate potential climatic effects on the mortality of individual trees. Stand and tree measures of competition, monthly and annual temperatures, and precipitation were statistically assessed against mortality through proportional hazards...

Urban trees can store carbon through the growth process and reduce fossil fuel use by lowering cooling and heating energy consumption of buildings through the process of transpiration, shading, and the blocking of wind. However, the planting and maintenance of urban trees come at a cost. We estimate the discounted cost of net carbon reductions associated with planting and caring for street trees in New York City (NYC) over 50- and 100-year horizons. Depending on the species planted, the cost of reducing carbon, averaged across planting locations, ranges from $3133 to $8888 per tonne carbon...