Treesearch

We used field surveys and Geographic Information System data to identify landscape-scale habitat associations of American martens (Martes americana) and to develop a model to predict their occurrence in northeastern California. Systematic surveys using primarily enclosed track plates, with 10-km spacing, were conducted across a 27,700 km2 area of largely forested, mountain terrain. Martens were detected at 20/184 (10.8%) of the sample units, aggregated in three distinct regions. We investigated habitat selection at multiple scales using circular assessment areas of 3, 20, and 80 km2. The...

In natural areas, families and friends can come together to have fun, celebrate important occasions or just relax and take time out. This immense social value is part of the 'glue' of a healthy society (Landy 2008). Several researchers have identified values from natural area visits to include social cohesion, improved mental health, improved physical health, stress relief, and psychological wellbeing (Gobster 2005, Manning & More 2002, Williams 2006).

Youth Day, held in Griffith Park in Los Angeles, California, was an exploratory study to determine whether technology attracts kids to outdoor activities. Four activities were offered—two were dependent on technology and two were not. The two technology-dependent activities were a camera safari and geocaching for treasure. The activities not dependent on technology were paper etching or rubbings of natural surfaces and a nature scavenger hunt. Thirty-eight young people (ages 6 to 17) participated in the activities. The children voted on how much they liked each activity. The technology-depe...

In a statewide survey in Oregon, parents indicated how much time their child spent outdoors relative to their own outdoor childhood experiences. The results indicated children spent as much time as their parents did as children in structured outdoor activities (such as organized sports), but they spent much less time than their parents did as children in outdoor chores and outdoor play (Lindberg 2007). The same study found that outdoor skills have changed over the generations, with younger generations having fewer nature-based outdoor skills (such as pitching a tent or cooking outdoors) in...

In a statewide survey in Oregon, parents indicated how much time their child spent relative to their own outdoor childhood experiences. The results indicated children spent as much time as their parents at that age in structured outdoor activities, such as organized sports, but they spent much less time than their parents did at that age in outdoor chores and unstructured outdoor play (Lindberg 2007). The same study found that outdoor skills have changed over the generations, with younger generations having fewer nature-based outdoor skills, such as pitching a tent or cooking outdoors in...

A recent survey revealed that the newly invasive banded elm bark beetle, Scolytus schevyrewi, was much more abundant than the long-established European elm bark beetle, S. multistriatus, in areas of Colorado and Wyoming, USA. This study was initiated to determine whether competitive displacement of S. multistriatus by S. schevyrewi might be mediated by a sequence of behavioral interactions between the species on and below the bark surface. At the first step in the sequence, host acceptance behavior (i.e., time to tunnel into the host) was monitored among female S. schevyrewi and S....

The western pine beetle, Dendroctonus brevicomis LeConte (Coleoptera: Curculionidae: Scolytinae), is a major cause of ponderosa pine, Pinus ponderosa Dougl. ex Laws., mortality in much of western North America. Currently, techniques for managing D. brevicomis infestations are limited. Verbenone (4,6,6-trimethylbicyclo [3.1.1] hept-3-en-2-one) is an antiaggregation pheromone of several Dendroctonus spp., including D. brevicomis, and it has been registered as a biopesticide for control of mountain pine beetle, Dendroctonus ponderosae Hopkins, and southern pine beetle, Dendroctonus frontalis...

Nitric acid vapor is produced by the same photochemical processes that produce ozone. In the laboratory, concentrated nitric acid is a strong acid and a powerful oxidant. In the environment, where the concentrations are much lower, it is an innocuous source of plant nitrogen. As an air pollutant, which mode of action does dry deposition of nitric acid follow? We investigated the effects of dry deposition of nitric acid on the foliage of four tree species native to the western United States. A novel controlled environment, fumigation system enabled a four-week exposure at concentrations...

Dry deposition of nitric acid vapor (HNO(3)) is a major contributor to eutrophication of natural ecosystems. Although soil fertilization by nitrogen deposition is considered to be the primary pathway for changes in plant nutrient status and shifts in ecological structure, the aerial portion of plants offer many times the surface area in which to collect atmospheric HNO(3). As much as 60% of deposited nitrogen may be retained in the canopy and not land on the soil surface below. Although uptake and assimilation appears to contribute to retention, only a small percentage of dry deposition is...

The western Mojave Desert is downwind of nitrogen emissions from coastal and inland urban sources, especially automobiles. The objectives of this research were to measure reactive nitrogen (N) in the atmosphere and soils along a N-deposition gradient at Joshua Tree National Park and to examine its effects on invasive and native plant species. Atmospheric nitric acid (HNO3) and ozone (O3) were elevated in western Joshua Tree National Park, and there were some high levels of atmospheric ammonia (NH3) in the east that may be related to local sources. The central areas of Joshua Tree National...