Treesearch

A summary of the literature on relationships between climate and various types of tree diseases, and the potential effects of climate change on pathogens in western North American forests is provided. Climate change generally will lead to reductions in tree health and will improve conditions for some highly damaging pathogens. Sections on abiotic diseases, declines, canker diseases, root diseases, Phytophthoras, foliar diseases, stem rusts of pine, mistletoes, and wood decays present some examples of potential disease effects with predicted climate change. The effects of climate change on...

Natural landscapes are increasingly subjected to impacts associated with urbanization, resulting in loss and degradation of native ecosystems and biodiversity. Traditional classification approaches to the characterization of urbanization may prove inadequate in some human-modified landscapes where complex and unique combinations of conditions can make classification and delineation of patches difficult. We describe a model that depicts existing human development as a fine-grained continuous variable using parcel-based land use data and transportation networks. We derived percent development...

Research that connects the effects of urbanization on biodiversity and ecosystem services is lacking. Ants perform multifarious ecological functions that stabilize ecosystems and contribute to a number of ecosystem services. We studied responses of ant communities to urbanization in the Lake Tahoe basin by sampling sites along a gradient of urban land development. We sampled ant communities, measured vegetation characteristics, quantified human activities, and evaluated ant-community responses by grouping ants into service-providing units (SPUs), defined as a group of organisms and their...

How climate change may affect parasite–host assemblages and emerging infectious diseases is an important question in amphibian decline research. We present data supporting a link between periods of unusually warm summer water temperatures during 2006 and 2008 in a northern California river, outbreaks of the parasitic copepod Lernaea cyprinacea, and malformations in tadpoles and young of the year Foothill Yellow-legged Frogs (Rana boylii). Relative to baseline data gathered since 1989, both 2006 and 2008 had significantly longer periods when daily mean water temperatures exceeded 20°C...

We investigated the subspecific identity of a rediscovered population of American martens within the range of a presumed extinct subspecies (Martes americana humboldtensis) by comparing mitochondrial DNA sequence diversity from contemporary individuals within the described ranges of M. a. humboldtensis, nearby ranges of M. a. caurina and M. a. sierrae, and a museum specimen of M. a. humboldtensis. Martens from the rediscovered population shared a haplotype (#2) with the museum specimen. This haplotype was found only in the coastal regions of Oregon and California, suggesting that the...

American martens use resting habitat between periods of activity to provide both thermal refugia and protection from predators. Maintenance or restoration of key elements of marten resting habitat, such as resting structures, requires that managers recognize their characteristics to protect them, or manage for their creation. We measured resting habitat at 4 scales: (1) the resting location—where the marten actually rested; (2) the resting structure—the habitat element that contained the resting location; (3) the resting site—characteristics in the immediate vicinity of each resting...

Annual molts and the subsequent plumages they produce are a ubiquitous element of avian life history. Research pertaining to the utility of molt and plumage has produced a robust framework of age-categorization for the vast majority of temperate avifauna. In comparison to temperate bird species, however, we know very little about resident topical bird molt and plumage. Published data pertaining to molt and plumage sequences are limited in scope, covering few species, and, to our knowledge, are not currently synthesized. Here we combine new information gathered from field and museum...

From February 13 to 28, 2009 I had the good fortune of visiting Australia, and touring urban forests in Sydney, Canberra, Brisbane, and Melbourne. My visits were only a day or two in each city, so in no case did I get an in-depth view of the urban forest resource or its management. The following observations are based on rather superficial field assessments and brief discussions with city arborists, researchers, and consultants.

Climatic changes induced by the El Niño–Southern Oscillation (ENSO) commonly influence biological systems; however, climatic variability and multitrophic interactions within tropical latitudes remain poorly understood. We examined relationships between migrant condition and ENSO during spring migration in Costa Rica. Our study is based on correlating an ENSO index with body-condition metrics of six Nearctic–Neotropic migrant bird species during stopover in Costa Rica over a 10-year period. This study is the first to report correlations between El Niño and changes in condition of multiple...

One goal of the ISA’s Science and Research Committee is to increase appreciation and investment in research. This article will explain why your commitment to science and research is vital to your professional growth and the future of arboriculture and urban forestry.