Treesearch

A mass timber lateral force resisting system (LFRS) is proposed using a mass timber buckling restrained brace (TBRB) to improve the seismic resilience of mass timber buildings. To develop a resilient braced frame, it is essential to understand and quantify the behavior of the connections, including the possible failure modes and moment-rotation capacities. Cyclic and monotonic tests were conducted on six mass timber beam-column connections to study the response of a mass timber joint connected with slotted-in steel plates and mild steel dowels. The primary goal of the subassembly tests was...

Several material properties of wood are directionally dependent. Mechanical properties such as tension, compression, and bending strength vary greatly for the same piece of wood when tested parallel to the grain (longitudinally), perpendicular to the grain and parallel to the annual rings (tangentially), or perpendicular to both the grain and rings (radially). For this reason, wood is often considered to be a cylindrically orthotropic anisotropic material. The orthotropy extends to dielectric properties of wood. However, in the presence of internal decay, the directional dependency of the...

The hemlock woolly adelgid (HWA, Adelges tsugae, Hemiptera: Adelgidae) is an invasive insect that threatens the ability to maintain eastern hemlock (Tsuga canadensis) and Carolina hemlock (Tsuga caroliniana) as ecologically functional components of eastern North American forests. Since the early 1990s, a classical biological control program for HWA has been pursued using insect predators from regions of Asia and western North America where the adelgid is native. Early efforts to establish ladybird beetles (Coleoptera: Coccinellidae) resulted in the establishment of Sasajiscymnus tsugae...

The Tahoe-Central Sierra Initiative (TCSI) Blueprint for Resilience (hereafter TCSI Blueprint) is a set of strategy maps that identify opportunities for forest protection and adaptation across a 978 381-ha (2.4 million-ac) region of the central Sierra Nevada. The TCSI partners, along with scientists and forest managers versed in the concept of resilience, defined resilience based on 10 ecological and social pillars. The TCSI Blueprint includes evaluations of 30 unique metrics, such as large tree density and probability of high-severity fire, that describe conditions across five of the...

Background In California’s mixed-conifer forests, fuel reduction treatments can successfully reduce fire severity, bolster forest resilience, and make lasting changes in forest structure. However, current understanding of the duration of treatment effectiveness is lacking robust empirical evidence. We leveraged data collected from 20-year-old forest monitoring plots within fuel treatments that captured a range of wildfire occurrence (i.e., not burned, burned once, or burned twice) following initial plot establishment and overstory thinning and prescribed fire treatments. Results Initial...

Armillaria root disease is among the largest causes of mortality and lost productivity of widely ranging horticultural, urban, and forest trees and shrubs in diverse boreal, temperate, and tropical regions around the world (Kim et al. 2022). Damage from Armillaria root disease will likely increase in response to changing climate and extreme weather because environmental stress can predispose host trees to Armillaria root disease (Kim et al. 2021; Murray and Leslie 2021).

Background: Native pinyon (Pinus spp.) and juniper (Juniperus spp.) trees are expanding into shrubland communities across the Western United States. These trees often outcompete with native sagebrush (Artemisia spp.) associated species, resulting in increased canopy fuels and reduced surface fuels. Woodland expansion often results in longer fire return intervals with potential for high severity crown fire. Fuel treatments are commonly used to prevent continued tree infilling and growth and reduce fire risk, increase ecological resilience, improve forage quality and quantity, and/or improve...

Understanding how human infrastructure and other landscape attributes affect genetic differentiation in animals is an important step for identifying and maintaining dispersal corridors for these species. We built upon recent advances in the field of landscape genetics by using an individual-based and multiscale approach to predict landscape-level genetic connectivity for grizzly bears (Ursus arctos) across ~100,000 km2 in Canada's southern Rocky Mountains. We used a genetic dataset with 1156 unique individuals genotyped at nine microsatellite loci to identify landscape characteristics that...

Effects of dry-season rains in the tropics may vary among arthropod taxa with potential consequences for arthropod consumers. To study rainfall effects on availability of different arthropod prey for Setophaga kirtlandii (Kirtland’s Warbler) and other surfacegleaning avian insectivores, we sampled late dry-season (March–April) arthropods over 9 years in an early succession dry forest on Eleuthera, The Bahamas. We sampled arthropods on foliage (with branch clips) and on the ground surface (with 5-min scans) to document variation in biomass and occurrence with prior rainfall for different...

The North Bay area of California is a populous and ecologically diverse area that has experienced significant changes in the past century, as well as a series of recent wildfires, after over a century of fire suppression practices. While much research has been conducted quantifying drivers and patterns of vegetation change in conifer-dominated ecosystems, and how such changes have influenced current trends in fire behavior, studies of similar focus and scale are rarer in non-conifer ecosystems, including mixed-hardwood forests or shrub-dominated ecosystems in central and coastal Northern...