Treesearch

The past decade has given rise to exciting new developments in the field of community ecology that have profound implications for biological control. The recognition that biological invasions offer unprecedented opportunities to investigate the nature of community assembly has swept invasive species studies to the forefront of popular ecology. Meanwhile, progress in research on facilitation, competition, predation, parasitism, behavior, complexity and diversity has lead to greater understandings of the roles these forces play in determining the strength and nature of direct and indirect...

Geospatial species sample data (e.g., records with location information from natural history museums or annual surveys) are rarely collected optimally, yet are increasingly used for decisions concerning our biological heritage. Using computer simulations, we examined factors that could affect the performance of autologistic regression (ALR) models that predict species occurrence based on environmental variables and spatially correlated presence/absence data. We used a factorial experiment design to examine the effects of survey design, spatial contiguity, and species detection probability...

It has been long established that the richness of vascular plant species and many animal taxa decreases with increasing latitude, a pattern that very generally follows declines in actual and potential evapotranspiration, solar radiation, temperature, and thus, total productivity. Using county-level data on vascular plants from the United States (3000 counties in the conterminous 48 states), we used the Akaike Information Criterion (AIC) to evaluate competing models predicting native and nonnative plant species density (number of species per square kilometer in a county) from various...

We simulated the effects of missing information on statistical distributions of animal response that covaried with measured predictors of habitat to evaluate the utility and performance of quantile regression for providing more useful intervals of uncertainty in habitat relationships. These procedures were evaulated for conditions in which heterogeneity and hidden bias were induced by confounding with missing variables associated with other improtant processes, a problem common in statistical modeling of ecological phenomena. Simulations for a large (N = 10 000) finite population representi...

In the last ten years, the fire management community has made significant advances in firefighter safety and leadership development. Yet, there is no discernible downward trend in entrapment fatalities. While the complexity of the job and exposure of an increasing number of firefighters to increasingly severe situations has surely increased over that time frame, the best we can say is that the trend is not increasing. This paper explores the question, how can we make significant advances toward reducing the likelihood of future firefighter fatalities? Signal detection theory provides a...

Habitat alteration can affect pollinating-insect community structure, decreasing the efficiency of pollinators on which many agricultural and natural ecosystems rely. Within the Tenderfoot Creek Experimental Forest (TCEF), located in the Little Belt Mountains of Central Montana, two different types of silvicultural techniques, even and group shelterwood, were applied to alter the natural habitats within the lodgepole pine (Pinus contorta) forests. Following logging, surveys of the flower-visiting insects and their floral resources were conducted within four treatments, even and group...

Environmental losses, each described along with its cause, were judged for seriousness. Four types of cause were studied: illegal behavior, carelessness, economic and population growth, and natural events. Identical environmental losses (e.g., of a herd of elk or a large stand of trees) were considered most serious when caused by illegal behavior or carelessness, and only slightly less serious when caused by growth. Losses due to these three types of human causes were considered much more serious than when the same losses were caused by natural events. Naturally caused environmental losses...

In response to the profound threat of exotic species to natural systems, much attention has been focused on the biotic resistance hypothesis, which predicts that diverse communities should better resist invasions. While studies of natural communities generally refute this hypothesis, reporting positive relationships between native species diversity and invasibility, some local-scale studies have instead obtained negative relationships. Most treatments of the topic have failed to recognize that all exotic invaders do not behave alike: while "weak" invaders become minor components of...

For the seven year period from 1998 to 2004, an average of almost 79,000 fires per year on U.S. Federal and State land burned a yearly average of over 22,000 km2. An average of 1 billion US dollars was spent on suppression each year by the Federal agencies alone. Variation in climate, vegetation, and population across the U.S. leads to significant differences in the timing of the fire season and in predominate fire cause. Fire danger rating and fire behavior prediction systems are used to support fire management decision-making in fire prevention, fire suppression, and fire use. The U.S....

During most of the past century, forest pathologists were limited to the study of pathogen phenotypes, vegetative compatibility, and mating reactions. These studies provided important insights in fungal taxonomy and phylogenetics, reproductive biology, and population genetics. However, these aspects are insufficiently variable or technically unfeasible for making inferences about intraspecific evolutionary processes (i.e., microevolution). Molecular techniques (Kim et. al., Chapter 2, this volume) and their application to population genetic analyses have given plant pathologists new tools...