Treesearch

Non-native forest pathogens can cause dramatic and long-lasting changes to the composition of forests, and these changes may have cascading impacts on community interactions and ecosystem functioning. Phytophthora ramorum, the causal agent of the emergent forest disease sudden oak death (SOD), has a wide host range, but mortality is concentrated in a few dominant tree species of coastal forests in California and Oregon. We examined interactions between P. ramorum and its hosts in redwood and mixed evergreen forest types over an 80,000 ha area in the Big Sur ecoregion of central California,...

Phytopthora borealis and Phytophthora riparia were identified in recent Phytophthora surveys in forest streams in Oregon, California and Alaska are described as new species in Phytophthora ITS Clade 6. They are similar in growth form and morphology to P. gonapodyides and are predominately sterile. They present unique DNA sequences, however, and differ in temperature and growth relations and geographic distribution.

The US Forest Service initiated its catchment research program in 1909 with the first paired catchment study at Wagon Wheel Gap, Colorado, USA. It has since developed the Experimental Forests and Ranges Network, with over 80 long-term research study sites located across the contiguous USA, Alaska, Hawaii, and the Caribbean. This network provides a unique, powerful continental research platform for study of complex environmental and societal problems at the local, regional and landscape scale. The study of water and ecosystems through paired catchment studies has been an integral component...

In this contribution we compile existing records from available sources of reliably identified Phytophthora species from forests and forest trees in Oregon, USA. A searchable version of this information may be found in the Forest Phytophthoras of the World Disease Finder (select USA-Oregon). We have included isolations from soil and streams in forests that are often not associated with any specific disease symptoms. Our goal is to inventory forest Phytophthora species, not forest diseases. On the other hand, we have included records from forest trees growing outside the forest, as Christmas...

Experimental watershed studies can provide answers to new challenges facing land managers and society including the impacts of fires and climate change on upstream and regional hydrology. The Cascabel Watersheds long-term prescribed fire study provides a unique opportunity to monitor climate change because of its location in an oak savanna situated between deserts or grasslands and the higher elevation oak-pine woodlands of the southwestern United States and northwestern Mexico. Continuing studies on the Cascabel Watersheds in southwestern New Mexico are evaluating the effects of cool-seaso...

Coues white-tallied deer (Odocoileus virginianus couesi) and desert cottontail (Sylvilagus auduboni), also known as Audubon cottontail, are inhabits of oak savannas in the Southwestern Borderlands region. Food, cover, and scattered water for these two species are found in this comparatively open ecosystem. The results of a study on the presence (occurrence) of Coues white-tailed deer and desert cottontail in unburned the oak savannas of the Southwestern Borderlands Region are presented in this paper. Effects of cool-season and warm-season prescribed burning and a wildfire on the presence...

Resistance to disease is determined by the genetic capacity of a plant to recognize and respond to a pathogen, as modified to varying degrees by the environment in which the interaction occurs. Physical factors such as temperature and moisture can limit the ability of a pathogen to infect and cause disease, and may also influence the response of the host through effects on gene expression and/or by imposing constraints on physiological activities required to deliver an effective defense. Recent research has also drawn attention to the potential for the biotic environment to modulate...

Pitch canker, caused by Fusarium circinatum, is a serious disease affecting Pinus radiata D. Don (Monterey pine) in nurseries, landscapes, and native forests. A typical symptom of pitch canker is canopy dieback resulting from girdling lesions on terminal branches (Gordon et al. 2001). More extensive dieback can result from coalescing lesions on large branches or on the main stem of the tree. The severity of disease depends, in part, on susceptibility of the individual tree. Some will suffer no more than a few infected branch tips, whereas others sustain extensive damage and may ultimately...

Results from previous studies of resistance in Norway spruce (Picea abies (L.) Karst.) to the pathogens Heterobasidion spp. show significant genotypic variation in fungal growth and spore susceptibility among Norway spruce clones. The genetic variation and the heritability are large enough for practical breeding purposes and there is no adverse correlation between Heterobasidion infection and growth traits. There is an economic incentive to use plant materials which are more resistant than those used in reforestation today. Recent research on developing the methods for testing resistance...

Beginning in the 1950s, researchers of the United States Department of Agriculture Forest Service established a series of paired watershed studies throughout north-central and eastern Arizona. A total of nine experimental watershed areas were established in the pinyon-juniper and chaparral woodlands, as well as the ponderosa pine and mixed conifer forests. While most of the experiments were "mothballed" in the early 1980s, a few studies continued until the early 1990s. Several were recently reinstated while others were never closed. Drought conditions in the southwestern part of the USA,...