Treesearch

Growing awareness of air pollution effects on forests has, from the early 1980s on, led to intensive forest damage research and monitoring. This has fostered air pollution control, especially in Europe and North America, and to a smaller extent also in other parts of the world. At several forest sites in these regions, there are first indications of a recovery of forest soil and tree conditions that may be attributed to improved air quality. This caused a decrease in the attention paid by politicians and the public to air pollution effects on forests. But air pollution continues to affect...

Atmospheric nitrogen (N) deposition is a recognized threat to plant diversity in temperate and northern parts of Europe and North America. This paper assesses evidence from field experiments for N deposition effects and thresholds for terrestrial plant diversity protection across a latitudinal range of main categories of ecosystems, from arctic and boreal systems to tropical forests. Current thinking on the mechanisms of N deposition effects on plant diversity, the global distribution of G200 ecoregions, and current and future (2030) estimates of atmospheric N-deposition rates are then...

The purpose of this investigation was to examine the influence of residents’ attachment to their homes and community on their willingness to adopt Firewise recommendations. Our sample was drawn from a population residing in the wildland–urban interface where the threat of wildfire is acute. The Firewise recommendations concerned 13 activities affecting home design, construction and maintenance, landscaping, and community engagement. Consistent with the tenets offered by the elaboration likelihood model of persuasion and empirical evidence stemming from the place and community attachment...

This first nationwide study of US Forest Service (USFS) law enforcement officers (LEOs) examined respondents’ roles in the USFS, what they perceived as their highest work priority, and what their relationship with the rest of the USFS should be. Results show that LEOs believe they have a high priority for protecting forest users and they believe that National Forest System line officers have higher priorities for protecting resources, employees, and public property. LEOs are evenly divided about whether their authority and jurisdiction are adequate for what they feel is expected or...

Three groups of wood-boring beetles—powderpost, deathwatch, and false powderpost (Table 1)—invade and damage wood furniture as well as structural and decorative wood inside of buildings. The beetle larvae feed in and do most of the damage to wood, and when they reach the adult stage, they emerge through round exit holes, which they create by chewing through the wood surface. Adults of some species also bore exit holes through plaster, plastic, and even soft metals that might cover the underlying wood.

Gas exchange responses to static and variable light were tested in three species: snap bean (Phaseolus vulgaris, two cultivars), California black oak (Quercus kelloggii), and blue oak (Q. douglasii). The effects of 1-month (snap beans) and 2-month (oaks) O3 (ozone) exposure (70 ppb over 8 h per day in open-top chambers) were investigated. A delay in stomatal responses (i.e., ‘sluggish’ responses) to variable light was found to be both an effect of O3 exposure and a reason for increased O3 sensitivity in snap bean cultivars, as it implied higher O3 uptake during times of disequilibrium....

Population variation in ecophysiological traits of four co-occurring montane conifers was measured on a large latitudinal gradient to quantitatively assess their potential for response to environmental change. White fir (Abies concolor) had the highest variability, gross photosynthetic rate (Pg), and foliar carbon (C) and nitrogen (N) content. Despite low water use efficiency (WUE), stomatal conductance (gs) of fir was the most responsive to unfavorable environmental conditions. Pinus lambertiana exhibited the least variability in Pg and WUE, and is likely to be the most vulnerable to...

We have been testing the practicality and efficacy of aerial application of Agri-Fos® for control of sudden oak death (SOD) in the Oregon tanoak (Lithocarpus densiflorus) forest. Helicopter application to forest stands has been compared with bole injection and groundbased spray application to seedlings and stump sprouts. We bio-assayed for Agri-Fos® uptake using twig and seedling inoculation with zoospores and bole wound inoculation. Experiments are continuing. Preliminary results indicate small but significant reductions in growth of Phytophthora ramorum in Agri-Fos® sprayed trees,...

It is assumed that large numbers of dead and down tanoak in forests infested by Phytophthora ramorum contribute to increased fire hazard risk and fuel loading. We studied the impact of P. ramorum infestation on surface fuel loading, potential fire hazard, and potential fire behavior in Douglas-fir- (Pseudotsuga menziesii) dominated forest stands with a significant tanoak (Lithocarpus densiflorus) component in Sonoma, Mendocino, Humboldt, and Del Norte Counties in northern coastal California. We also tested the feasibility of using stands in which tanoaks were treated with herbicides as a...

Although there is no known cure or preventative on a landscape scale for sudden oak death (SOD), the plant disease caused by Phytophthora ramorum, a variety of management options has been tested with the goal of developing an integrated program of treatment for the pathogen. This paper presents a first attempt to gather together individual management trials into an overall decision-making tool for landowners contemplating treatments for the disease. It conceptualizes these treatments as a matrix that matches available strategies—some of which are still substantially untested—to management...