Treesearch

We conducted an experimental study of infection, transmission, and persistence of a nucleopolyhedrovirus (NPV) of Douglas-fir tussock moth (Orgyia pseudotsugata) to better understand mechanisms determining the efficacy of the virus when it is used as a microbial control agent. In a field experiment, we quantified infection rates of larvae exposed to either Tussock Moth Biocontrol-1, the strain currently used for control by the U.S. Forest Service, or a wild-type strain isolated from a natural population. We first allowed each pathogen to decay on experimental branches for 0, 1, or 3 days...

In recent decades, dam removal has emerged as a viable national and international strategy for river restoration. According to American Rivers, a river conservation organization, more than 1,100 dams have been removed in the United States in the past 40 years, and more than half of these were demolished in the past decade. This trend is likely to continue as dams age, no longer serve useful purposes, or limit ecological functions. Factors such as dam size, landscape and channel features, and reservoir sediment characteristics differ widely, so dam removal projects must be evaluated...

Fire is both a natural and anthropogenic disturbance influencing the distribution, structure, and functioning of terrestrial ecosystems around the world. Many plants and animals depend on fire for their continued existence. Others species, such as rainforest plants species, are extremely intolerant of burning and need protection from fire. The properties of a fire regime are changing as the natural world’s landscapes become fragmented and human influence becomes pervasive. A sound understanding of fire and its effects on ecosystems is an essential prerequisite for effectively managing this...

Disturbances are major drivers of ecological dynamics and it is the cumulative effects of disturbances across space and time that define a disturbance regime and dictate biodiversity by influencing the ranges of vegetation structures, compositions, and processes on landscapes. This range and variation of landscape characteristics under historical disturbance regimes can form an envelope of viable conditions that can serve as important benchmarks or references in land management. Historical range and variation (HRV) is the expression of the full range of landscape characteristics that...

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is native to Asia and has become a severe agricultural and nuisance pest in the U.S. Therefore, foreign exploration was conducted in Asia to identify potential classical biological control agents. Several Trissolcus spp. (Hymenoptera: Scelionidae) parasitize H. halys eggs in Asia and are being evaluated for potential release in the U.S. Since H. halys has invaded regions that experience sub-zero winter temperatures, cold tolerance is important for evaluation of Trissolcus spp. Our study compared the cold tolerance of populations of T....

Patterns of local adaptation at fine spatial scales are central to understanding how evolution proceeds, and are essential to the effective management of economically and ecologically important forest tree species. Here, we employ single and multilocus analyses of genetic data (n = 116 231 SNPs) to describe signatures of fine-scale adaptation within eight whitebark pine (Pinus albicaulis Engelm.) populations across the local extent of the environmentally heterogeneous Lake Tahoe Basin, USA. We show that despite highly shared genetic variation (FST = 0.0069), there is strong evidence for...

A literature analysis was conducted to synthesize typical response rates from forest-productsindustry- based survey studies published from 2000 to mid-2015. One hundred and ninety-five surveys published in several forest products and forestry journals and proceedings (mostly North American based) were analyzed. Overall, the typical response rate was found to be about 26.0% (median) to 31.6% (mean). The median survey size in terms of number surveyed was 543.0, and the median for responses received was 131.5. Several factors were found to influence response rates and numbers surveyed. The...

Predicting the impact of drought on forest ecosystem processes requires an understanding of trees' species-specific responses to drought, especially in the Eastern USA, where species composition is highly dynamic due to historical changes in land use and fire regime. Here, we adapted a framework that classifies trees' water-use strategy along the spectrum of isohydric to anisohydric behavior to determine the responses of three canopy-dominant species to drought. We used a collection of leaf-level gas exchange, tree-level sap flux and stand-level eddy covariance data collected in south-centr...

Temperature profoundly affects ecology, a fact ever more evident as the ability to measure thermal environments increases and global changes alter these environments. The spatial structure of thermalscapes is especially relevant to the distribution and abundance of ectothermic organisms but the ability to describe biothermal relationships at extents and grains relevant to conservation planning has been limited by small or sparse datasets. Here, we combine a large occurrence database of >23,000 aquatic species surveys with stream microclimate scenarios supported by an equally large temperatu...

Our understanding of how climate and fire have impacted quaking aspen (Populus tremuloides Michx.) communities prior to the 20th century is fairly limited. This study analysed the period between 4500 and 2000 cal. yr BP to assess the pre-historic role of climate and fire on an aspen community during an aspen-dominated period.