Treesearch

Seedfall of coast Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco var. menziesii) has been studied at the forest edge-clearcut interface and in small canopy gaps, but it has not been evaluated in gap sizes that would be typical of a group-selection method of regeneration. In a mature Douglas-fir forest in the Puget Sound lowlands of western Washington, seedfall was measured by month in artificially created circular gaps 0.1, 0.2, 0.3, and 0.4 ha (0.25, 0.5, 0.75, and 1.0 ac, respectively) in size and in the forest matrix. Seedfall was assessed 1 year before and 2 years after gap creation,...

Although repeated fires are generally thought to reduce competition, direct tests of this hypothesis are rare. Furthermore, recent theory predicts that fires can increase competitive effects of fireresistant species on fire-sensitive species and thus create stable assemblages dominated by the former. In this study, I quantified competition between saplings of fire-resistant oaks and their fire-sensitive non-oak neighbors in adjacent, repeatedly-burned and unburned 1-ha plots following damage by a tornado that reduced canopy cover to 60%. Using field experiments with established in situ...

This article focuses on the collaborative and voluntary Wilderness Best Management Practices (WBMP) for managing recreation in Tracy Arm-Fords Terror Wilderness in Alaska. Stakeholder definitions of wilderness, opinions about the WBMP, and whether these opinions are reflective of their perceptions of wilderness are examined. Interviews with tour operators, agency personnel, cruise industry representatives, and local residents showed that most expressed some degree of purism in their definitions of wilderness (e.g. solitude and minimal impact), although cruise representatives had less...

Novel forests (NFs)—forests that contain a combination of introduced and native species—are a consequence of intense anthropogenic disturbances and the natural resilience of disturbed ecosystems. The extent to which NFs have similar forest function as comparable native secondary forests is a matter of debate in the scientific community. Little is known about the performance of individual species in those forests. This study focuses on the functional attributes of Castilla elastica NFs in Puerto Rico and on the differences between introduced and native species growing side by side in these...

Verbenone (4,6,6-trimethylbicyclo[3.1.1]hept-3-en-2-one) is an antiaggregant of the mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae), a notable forest insect capable of causing extensive levels of tree mortality in western North America. Several formulations of verbenone are registered for tree protection, but failures in efficacy are not uncommon, particularly when applied during large infestations. A formulation of (–)-verbenone was developed (SPLAT® Verb, ISCA Technologies Inc., Riverside, CA) and evaluated for protecting individual lodgepole pine, Pinus...

Many tropical islands have limited water resources with historically increasing demand, all potentially affected by a changing climate. The effects of climate change on island hydrology are difficult to model due to steep local precipitation gradients and sparse data. Thiswork uses 10 statistically downscaled general circulationmodels (GCMs) under two greenhouse gas emission scenarios to evaluate the uncertainty propagated from GCMs in projecting the effects of climate change on water resources in a tropical island system. The assessment is conducted using a previously configured hydrologic...

Several species of bark beetles (Coleoptera: Curculionidae, Scolytinae) are capable of causing significant amounts of tree mortality in conifer forests throughout much of the world. In most cases, these events are part of the ecology of conifer forests and positively influence many ecological processes, but the economic and social implications can be significant. Several tactics are available to manage bark beetle infestations and to reduce associated levels of tree mortality. Direct control involves short-term tactics designed to address current infestations by manipulating beetle...

GPS telemetry collars and their ability to acquire accurate and consistently frequent locations have increased the use of step selection functions (SSFs) and path selection functions (PathSFs) for studying animal movement and estimating resistance. However, previously published SSFs and PathSFs often do not accommodate multiple scales or multiscale modeling.

Most current methods to assess connectivity begin with landscape resistance maps. The prevailing resistance models are commonly based on expert opinion and, more recently, on a direct transformation of habitat suitability. However, habitat associations are not necessarily accurate indicators of dispersal, and thus may fail as a surrogate of resistance to movement. Genetic data can provide valuable insights in this respect.

Habitat fragmentation and habitat loss diminish population connectivity, reducing genetic diversity and increasing extinction risk over time. Improving connectivity is widely recommended to preserve the long-term viability of populations, but this requires accurate knowledge of how landscapes influence connectivity. Detectability of landscape effects on gene flow is highly dependent on landscape context, and drawing conclusions from single landscape studies may lead to ineffective management strategies. We present a novel approach to elucidate regional variation in the relative importance...