Treesearch

Sudden oak death (SOD), caused by Phytophthora ramorum, is lethal to tanoak (Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S.H. Oh), and threatens this species throughout its range in Oregon. The disease was first discovered in coastal southwest Oregon forests in July 2001. Since then an interagency team has been attempting to eradicate the pathogen through a program of early detection surveys followed by destruction of infected and nearby host plants. Eradication treatments eliminated disease from many infested sites, but the disease continued to spread slowly, predominantly...

This study looked at the factors that facilitated the spread of Phytophthora ramorum and P. kernoviae at two locations in the west of Scotland. Spore traps, river baiting, bait plants, and soil sampling were used to both confirm the presence of, and measure the amount of, inoculum in the environment in order to quantify the relationship between inoculum levels and disease development. Phytophthora ramorum was detected in spore traps at high levels under a sporulating host, but also at sites where hosts were not present, leading to the conclusion that inocula in low-level spore traps were...

Woodland (Plethodontid) salamanders occur in huge numbers in healthy forests in North America where the abundances of many species vary along successional gradients. Their high numbers and trophic role as predators on shredder and decomposer arthropods influence nutrient and carbon pathways at the leaf litter/soil interface. Their extreme niche conservatism and low vagility offer further advantages to the use of these salamanders as metrics of forest ecosystem condition. Mill Creek is a 103 km2 commercially logged redwood forest watershed acquired as parkland where original primary forest...

The Proceedings of the Sudden Oak Death Fifth Science Symposium provides an update on research to address sudden oak death, caused by the exotic, quarantine pathogen, Phytophthora ramorum. Over 60 submissions present national and international investigations covering pathogen biology, biosecurity, genetics, monitoring, fire ecology, and diagnostics. Several papers on disease status and progress toward nursery and wildland management are also included.

Numerous 'exotic' tree pathogens are arriving in Europe, North America, and elsewhere due to flaws in current international plant health sanitary and phytosanitary (SPS) protocols. These include lack of protection against the many organisms unknown to science, an emphasis on promoting trade rather than promoting environmental biosecurity, a steadily increasing globalization of the trade in rooted plants, and the failure of regulatory authorities to take meaningful and effective action (Brasier 2005, 2008; Liebhold et al. 2012,Webber 2010). The United Kingdom, for example, has experienced...

In managed forests dominated by true fir (Abies) species, stands are often restocked using understory trees retained during timber harvest, making the effects of dwarf mistletoe (Arceuthobium spp.) infestation on small true fir a concern. This study examined the response of small red (A. magnifica) and white (A. concolor) fir and their dwarf mistletoes (A. abietinum f.sp. magnificae and A. abietinum f.sp. concoloris, respectively) to precommercial thinning treatments in fir-dominated stands in the Sierra Nevada Mountains of California. Tree diameters and dwarf mistletoe ratings were...

In interior Alaska, increased use of mechanical fuel reduction treatments, increased interests in the use of wood energy systems as alternatives to fossil fuels, and elevated populations of northern spruce engraver, Ips perturbatus (Eichhoff), have raised concerns regarding the impact of this bark beetle to forest resources. We conducted a large-scale field study in 20092011 (Study 1) to determine the effects of slash scoring (mechanical by chainsaw versus none), slash distribution (scattered versus decked), and cutting date (spring versus fall) on I. perturbatus colonization of and...

The economic relevance of wildland fire management and protection programs is ever growing, particularly considering mounting wildfire costs and losses globally, and the justifications required for budget allocations to management and protection of forest ecosystems. However, there are major difficulties in grappling with the problem of rapidly increasing wildland fire management costs. For example, in the U.S., the U.S. Department of Agriculture Forest Service from 1997-2008 has spent more than $US11.5 billion on fire suppression alone, on wildfires affecting more than 26 million ha of...

Investigators generally pool observations of males and females in studies of the foraging behavior of sexually monochromatic songbirds. However, such pooling can obscure possible intersexual differences. We compared the foraging behavior of male and female Western Wood-Pewees (Contopus sordidulus), a sexually monochromatic species, in the Sierra Nevada Mountains of California during the breeding seasons of 2007 and 2008. We recorded 143 foraging observations (male N = 74, female N = 69). Overall, mean foraging rates of females (2.8 attacks/min) were higher (P <0.001) than those of males...

Recognition that predators have indirect effects on prey populations that may exceed their direct consumptive effects highlights the need for a better understanding of spatiotemporal variation in predator–prey interactions. We used photographic monitoring of tethered Rainbow Trout Oncorhynchus mykiss and Cutthroat Trout O. clarkii to quantify predator encounter rates for fish in four streams of northwestern California during winter–spring and summer. To estimate maximum encounter rates, provide the clearest contrast among streams and seasons, and provide an empirical estimate of a key...