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Sudden oak death (SOD), caused by Phytophthora ramorum, is an emerging forest disease associated with extensive tree mortality in coastal California forests (Rizzo et al. 2005). P. ramorum is a generalist pathogen that infects many hosts, but hosts differ in their ability to transmit the disease and in the impacts caused by the disease. In coast redwood forests, tanoak (Notholithocarpus densiflorus) is the main host dying from SOD and the main source of pathogen inoculum. SOD leads to compositional changes in these habitats through selective mortality of tanoak. The effect of SOD on forest...

1. Few pathogens are the sole or primary cause of species extinctions, but forest disease has caused spectacular declines in North American overstorey trees and restructured forest ecosystems at large spatial scales over the past 100 years. These events threaten biodiversity associated with impacted host trees and other resources valued by human societies even when they do not directly cause host extinction. 2. Invasion of Phytophthora ramorum and emergence of the forest disease sudden oak death has caused a large-scale decline of tanoak (Notholithocarpus densiflorus) in Californian...

Whole and partial genome sequences are becoming available at an ever-increasing pace. For many plant pathogen systems, we are moving into the era of genome resequencing. The first Phytophthora genomes, P. ramorum and P. sojae, became available in 2004, followed shortly by P. infestans in 2006. Availability of whole genome sequences has provided rapid and immediate advances in several areas also resulting in many practical applications and critical new insights. Availability of comparative genome data facilitated discovery of new classes of effectors, such as the RxLR-dEER and crinkler...

The recently emerged plant pathogen Phytophthora ramorum is responsible for causing the sudden oak death epidemic. This review documents the emergence of P. ramorum based on evolutionary and population genetic analyses. Currently infection by P. ramorum occurs only in Europe and North America and three clonal lineages are distinguished: EU1, NA1 and NA2. Ancient divergence of these lineages supports a scenario in which P. ramorum originated from reproductively isolated populations and underwent at least four global migration events. This recent work sheds new light on mechanisms of...

Phytophthora ramorum, an oomycete plant pathogen, is the causal agent of sudden oak death, a serious disease of Fagaceous trees in California and Oregon over the last decade. Tanoak (Notholithocarpus densiflorus) is one of the most susceptible host species, but the cause of host mortality is poorly understood. Previous research has implicated disruption in stem water transport, phloem girdling, and activity of a class of secreted proteins known as elicitins as possible mechanisms of pathogenesis. In this study I investigated certain physiological impacts of P. ramorum infection on tanoak...

Limited open-grown urban tree species biomass equations have necessitated use of forest-derived equations with diverse conclusions on the accuracy of these equations to estimate urban biomass and carbon storage. Our goal was to determine and explain variability among estimates of CO2 storage from four sets of allometric equations for the same ground sample of 640 trees. We also compared the variability found in CO2 stored and sequestered per hectare among estimation apporaches for Sacramento's urban forest with the variation found among six other cities. We found substantial variability...

The oomycete pathogen Phytophthora ramorum is responsible for sudden oak death (SOD) in California coastal forests. P. ramorum is a generalist pathogen with over 100 known host species. Three or four closely related genotypes of P. ramorum (from a single lineage) were originally introduced in California forests and the pathogen reproduces clonally. Because of this the genetic diversity of P. ramorum is extremely low in Californian forests. However, P. ramorum shows diverse phenotypic variation in colony morphology, colony senescence, and virulence. In this study, we show that phenotypic...

There has been widespread interest in applying new forest practices based on concepts presented in U.S. Forest Service General Technical Report PSW-GTR-220, "An Ecosystem Management Strategy for Sierran Mixed-Conifer Forests." This collection of papers (PSW-GTR-237) summarizes the state of the science in some topics relevant to this forest management approach, presents case studies of collaborative planning efforts and field implementation of these new practices, and clarifies some of the concepts presented in GTR 220. It also describes a method for assessing forest heterogeneity at the...

The temporal-spatial planning of activities for a territorial fire management program requires knowing the value of forest ecosystems. In this paper we extend to and apply the economic valuation principle to the concept of economic vulnerability and present a methodology for the economic valuation of the forest production ecosystems. The forest vulnerability is analyzed from criteria intrinsically associated to the forest characterization, and to the potential behavior of surface fires. Integrating a mapping process of fire potential and analytical valuation algorithms facilitates the...

To address the impacts of climate change, land managers need techniques for incorporating adaptation into ongoing or impending projects. We present a new tool, the Climate Project Screening Tool (CPST), for integrating climate change considerations into project planning as well as for developing concrete adaptation options for land managers. We designed CPST as part of the Westwide Climate Initiative project, which seeks to develop adaptation options for addressing climate change through science/management partnerships. The CPST lists projected climate trends for the target region and...