This paper examines the invasion of exotic wilding conifers on the native tussock grasslands of Aotearoa New Zealand. The investigation includes two studies and aims to better understand the structure of Pinus contorta seeds across tree crown positions and the viability rates of P. contorta seeds produced during a trees...
Land management agencies are faced with decreasing budgets and staff, even as acres in need of restoration treatment are increasing. Rural communities in the West are still suffering from sharp declines in timber harvests since the 1990s and are now contending with wildfires that are increasing in size and severity....
Black stain root disease (BSRD) is a vascular wilt disease of conifers caused by three varieties of the native, insect-vectored fungal pathogen, Leptographium wageneri (L. wageneri var. wageneri, L. wageneri var. ponderosum, and L. wageneri var. pseudotsugae). Although morphological, physiological, and ecological characteristics differ among the three varieties of L....
Douglas-fir needle midge (Contarinia pseudotsugae, Diptera: Cecidomyiidae) is a native invasive species in Pacific Northwest Christmas tree farms, seed orchards, and nurseries where Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) is present. Douglas-fir needle midge (DFNM) causes discoloration and galls on the needles, thereby it affects the market value of the Christmas...
Hemlock dwarf mistletoe (Arceuthobium tsugense subsp. tsugense) is an arboreal, hemiparasitic plant that principally parasitizes western hemlock (Tsuga heterophylla). Hemlock dwarf mistletoe exerts a profound influence on infected trees that can drastically change the structure of the tree crown due to reduced growth, top dieback, branch deformation and death, resulting...
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David C. Shaw
Hemlock dwarf mistletoe (Arceuthobium tsugense subsp. tsugense) is an
Swiss needle cast (SNC) is a foliage disease of Douglas-fir caused by Nothophaeocryptopus gaeumannii, an Ascomycete fungus (Mycosphaerellaceae) that causes growth reductions in Douglas-fir plantations across the Pacific Northwest. Epidemiology of the fungus is generally well known in plantation trees, but the relationship between disease expression and foliage nutrition and...
This study explored the relationship of mature ponderosa pine (Pinus ponderosa Dougl. ex Laws) tree vigor and competitive zone density following thinning and fuel reduction treatments. Competitive zone density (CZD) was defined as the total tree basal area (m²/ha) surrounding a given ponderosa pine tree within a 10m fixed radius...
Douglas-fir (Pseudotsuga menziesii) is a commercially and ecologically important tree species native to western North America. The foliar pathogens Phaeocryptopus gaeumannii, the causal agent of Swiss Needle Cast, and Rhabdocline species, the causal agents of Rhabdocline needle cast, are two important pathogens specific to Douglas-fir. These pathogens are highly influenced...
As species of ash trees become increasingly threatened worldwide by exotic pests and pathogens, it is important to develop descriptions of their ecologies that help guide the conservation and restoration of forests in which they are a major component. Oregon ash (Fraxinus latifolia) is a dominant tree species in wetland...
In the last 200 years there have been significant declines in the amount and structural complexity of oak-dominated forests and savannahs in the Pacific Northwest. Restoring oak systems often involves selectively thinning stands of oaks in order to reduce competition for sunlight. In choosing which trees to cut, land managers...