Treesearch

From 2000 through 2012, we collected annual observations on disease symptoms and stand conditions in 128 coast live oak plots in forests affected by sudden oak death (SOD), caused by the introduced pathogen Phytophthora ramorum. Elevated rainfall in one or both of the previous wet seasons was associated with pulses of new infections. However, persistent differences in infection rates between nearby locations and among plots within locations show that tree and site specific factors influence disease risk on the local scale. Because California bay is the primary source of P. ramorum spores...

In response to the wave of sudden oak death (SOD), caused by Phytophthora ramorum, sweeping the redwood forest ecosystems of California's North Coast, the role of foresters and other ecosystem managers is being tested. On Bear Flat Tree Farm, near Healdsburg, California, Forest, Soil & Water, Inc. (FSW) has conducted a multi-year, multi-treatment approach to take advantage of SOD. Because the seral stage of tanoak is a component of hardwood dominance intermediary between brush and conifers, FSW has used the oncoming wave of SOD to accelerate the ecosystem towards redwood (Sequoia sempervire...

The unmitigated risk potential of the introduction of exotic insects and pathogens to Hawai'i was evaluated for its impact on native plants, specifically Acacia koa, Cibotium spp., Dicranopteris linearis, Diospyros sandwicensis, Dodonaea viscosa, Erythrina sandwicensis, Leptecophylla tameiameiae, Metrosideros polymorpha, Myoporum sandwicense, Pandanus tectorius, Scaevola spp., Sophora chrysophylla, and Vaccinium spp. Assessments were made by estimating the likelihood and consequences of introduction of representative insects and pathogens of concern. Likely pathways of introduction were...

Numerous ordinances and laws recognize the value of oak trees and woodlands, and dictate serious and expensive consequences for removing or harming them. Unfortunately, the methods used to calculate these values are equally numerous and often inconsistent. More important, these ordinances typically lack economic incentives to avoid impacts to oak woodland values because they fail to clearly identify the economic consequences of oak woodland loss; specifically: non-use values (recreation, aesthetics, and so forth), use values (increased real estate value, Council of Tree and Landscape...

The California Oak Woodlands Conservation Act (AB 242 2001) established requirements for the preservation and protection of oak woodlands and trees, and allocated funding managed by the Wildlife Conservation Board. In order to qualify to use these funds, counties and cities need to adopt an oak conservation management plan. Between 2008 and 2011, a team of concerned arborists, biologists, county foresters, planners, and other stakeholders wrestled with questions such as how to define an oak woodland in southern California, how much oak woodlands are worth, and examined the costs associated...

East Side Potter Valley (ESPV) Road is a heavily used rural collector road running north/south through the unincorporated area of Mendocino County known as Potter Valley. The roadway is significantly deteriorated and in need of repair and upgrade. The Mendocino County Department of Transportation (MCDOT) road project encompasses approximately 6.4 km of roadway that will be rehabilitated, straightened, and widened to bring the road section up to federal highway safety standards. An estimated 144 utility poles and miles of ditches will require relocation to accommodate the widening. New pole...

Tejon Ranch, encompassing 109 000 ha, is the largest contiguous private property in California. In 2008, the Tejon Ranch Company and a coalition of five environmental organizations executed the Tejon Ranch Conservation and Land Use Agreement that placed 90 percent of the property into permanent conservation and created the Tejon Ranch Conservancy as its steward. Tejon Ranch supports extensive, diverse, and regionally significant oak woodlands. The Conservancy is characterizing the composition and structure of these woodlands to inform land management. Deciduous oak woodlands at Tejon Ranch...

California deciduous oak woodlands provide many ecological, cultural, and economic benefits, and often represent unique plant communities that harbor native rare and declining species. Oak woodlands have suffered substantial losses in area and ecological integrity in the post-settlement era due to land conversion and widespread fire exclusion. Remnant oak woodlands in many areas are undergoing further conversion to conifer forest as shade-tolerant, and often less fire-tolerant species invade and increase in abundance. This process, known as conifer encroachment, has been identified across...

The loss of oak woodlands to conifer encroachment is widely recognized as a major conservation concern. The increased occupancy of oak woodlands by Douglas-fir (Pseudotsuga menziesii) and other conifers has been reported throughout portions of California and the Pacific Northwest in multiple oak habitat types. In California, Oregon white oak (Quercus garryana) and California black oak (Quercus kelloggii) are particularly impacted by encroachment. Studies point to altered disturbance regimes, and the suppression of low-intensity fire in particular, as the primary cause of increased conifer...

Conifer encroachment into oak woodlands is becoming a pressing concern for oak conservation, particularly in California's north coast. We use Object-Based Image Analysis (OBIA) with historical aerial imagery from 1948 and recent high-spatial-resolution images from 2009 to explore the potential for mapping encroachment using remote sensing. We find that pre-processing historical aerial imagery is time-consuming and that OBIA requires training and experience but has promise for mapping the phenomenon of interest. We also find that identifying conifer and oak in the imagery without ground-base...