Treesearch

Many tribes in California and Oregon value California black oak (Quercus kelloggii) as a traditional source of food and other values. Over centuries or millennia, Native Americans learned that they could enhance production of desired resources by regularly igniting low-intensity surface fires in stands of black oak. Although black oak is likely to remain widespread in the future, a warming climate, increasingly dense forests, and altered fire regimes threaten the large, full-crowned mature trees that produce crops of high-quality acorns and provide cavities for many wildlife species. To...

This work focuses broadly on individual, live shrubs and, more specifically, it examines bulk density in chaparral and its combined effects with wind and ignition location on the resulting fire behaviour. Empirical functions to predict bulk density as a function of height for 4-year-old chaparral were developed for two typical species of shrub fuels in southern California, USA, namely chamise (Adenostoma fasciculatum Hook & Arn.) and manzanita (Arctostaphylos spp. Adans.). Fuel beds of chamise foliage and small-diameter branches were burned in an open-topped wind tunnel. Three levels of...

Multi-temporal satellite imagery can provide valuable information on the patterns of vegetation growth over large spatial extents and long time periods, but corresponding ground-referenced biomass information is often difficult to acquire, especially at an annual scale. In this study, we test the relationship between annual biomass estimated using shrub growth rings and metrics of seasonal growth derived from Moderate Resolution Imaging Spectroradiometer (MODIS) spectral vegetation indices (SVIs) for a small area of southern California chaparral to evaluate the potential for mapping...

In 2013, while surveying for five-needle white pine cone crops in northeastern Nevada, we observed white pine blister rust, caused by the rust pathogen Cronartium ribicola Fisch., infecting branches and stems of limber pines (Pinus flexilis James) on Pine Mountain (41.76975°N, 115.61622°W), Humboldt National Forest, Elko County, Nevada. Nearby whitebark pines (P. albicaulis Engelm.) were also infected. Pine Mountain rises to 2,636 m, is sparsely forested, and is located 11.25 km west of the Jarbidge Mountains, where infection by blister rust on whitebark pine was first reported at Coon...

Patterns of local adaptation at fine spatial scales are central to understanding how evolution proceeds, and are essential to the effective management of economically and ecologically important forest tree species. Here, we employ single and multilocus analyses of genetic data (n = 116 231 SNPs) to describe signatures of fine-scale adaptation within eight whitebark pine (Pinus albicaulis Engelm.) populations across the local extent of the environmentally heterogeneous Lake Tahoe Basin, USA. We show that despite highly shared genetic variation (FST = 0.0069), there is strong evidence for...

Forest managers are challenged with meeting numerous demands that often include wildlife habitat and carbon (C) sequestration. We used a probabilistic framework of wildfire occurrence to (1) estimate the potential for fuel treatments to reduce fire risk and hazard across the landscape and within protected California spotted owl (Strix occidentalis occidentalis) habitat and (2) evaluate the consequences of treatments with respect to terrestrial C stocks and burning emissions. Silvicultural and prescribed fire treatments were simulated on 20% of a northern Sierra Nevada landscape in three...

Climate change is expected to affect air temperature and watershed hydrology, but the degree to which these concurrent changes affect stream temperature is not well documented in the tropics. How stream temperature varies over time under changing hydrologic conditions is difficult to isolate from seasonal changes in air temperature. Groundwater and bank storage contributions to stream flow (i.e., base flow) buffer water temperatures against seasonal and daily fluctuations in solar radiation and air temperature while rainfall-driven runoff produces flooding events which also influence...

Conservation and restoration of ecosystems impacted by nonnative ungulates increasingly involves their removal and exclusion. While the influence of nonnative ungulate removal on plant communities is commonly monitored, impacts on underlying ecological processes are seldom quantified. Here we examined how nonnative feral pig (Sus scrofa) removal from Hawaiian tropical montane wet forests affects soil physical and chemical properties. Unique to this study, measurements were taken in paired sites inside and outside of five feral pig removal units representing a ~20 year, highly constrained...

Fire suppression in many dry forest types has left a legacy of dense, homogeneous forests. Such landscapes have high water demands and fuel loads, and when burned can result in catastrophically large fires. These characteristics are undesirable in the face of projected warming and drying in the western US. Alternative forest and fire treatments based on managed wildfire—a regime in which fires are allowed to burn naturally and only suppressed under defined management conditions—offer a potential strategy to ameliorate the effects of fire suppression. Understanding the long-term effects of...

People in industrialized countries may be losing their connection with nature. The Get to Know Program (Get to Know) is a multi-faceted program aimed at encouraging direct connection with nature through a variety of activities (observations of wildlife, hiking, creative arts, and special events), specifically among youth. Three studies assessed the effects of three Get to Know program activities on youth's implicit connectedness with nature (measured using a computer based game). Participants were youth recruited from southern California schools or youth organizations. Participation in the...