Treesearch

Several studies have shown that large wood has a prominent role in habitat quality, however there is little research on the role of wood on pool characteristics and other habitat components in low gradient streams (channel slopes less than one percent). Longitudinal profiles are used to analyze general residual pool characteristics of three approximately 1000-meter stream reaches with similar stream and watershed characteristics and vastly different large wood loadings (759 vs. 329 vs. 39 m3/ha). This study devises a new classification methodology to subdivide long pools, due to different...

Coast redwood (Sequoia sempervirens) is one of the rare conifers to reproduce successfully through clonal spread. The importance of this mode of reproduction in stand development is largely unknown. Understanding the importance of clonal spread and the spatial structure of clones is crucial for stand management strategies that would aim to maximize genetic diversity. We have developed genetic markers to identify the clonal structure of nine second-growth redwood stands in Jackson Demonstration State Forest, California. Clonal spread was found to be important in the development of these...

Tree pathogens can affect community composition and structure over wide areas. Phytophthora ramorum, cause of sudden oak death (SOD), occurs in the wild in California from Humboldt County to southernmost Monterey County. P. ramorum has killed many trees at some sites and may spread to affect near and distant forests. The pathogen has not yet been detected in San Luis Obispo County outside of nurseries, but threatens coast live oak (Quercus agrifolia) woodlands there. SOD-induced changes in vegetation structure and tree community composition may cascade to affect vertebrate communities....

Pre Euro-American settlement forest structure and fire regimes for Jeffrey pine-white fir, red fir-western white pine, and lodgepole pine forests were quantified using stumps from trees cut in the 19th century to establish a baseline reference for ecosystem management in the Lake Tahoe Basin. Contemporary forests varied in different ways compared to the presettlement reference. Contemporary Jeffrey pine-white fir forests have more and smaller trees, more basal area, less structural variability, and trees with a more clumped spatial distribution than presettlement forests. The mean presettle...

A detailed study of canopy fuel characteristics in five different forest types provided a unique dataset for simulating the effects of various stand manipulation treatments on canopy fuels. Low thinning, low thinning with commercial dbh limit, and crown thinning had similar effects on canopy bulk density (CBD) and canopy fuel load (CFL), but only the strict low thinning significantly affected canopy base height (CBH). In four of five sampled stands, CBD and CFL responded linearly to increasing treatment intensity in those three thinning treatments. The ponderosa-pine/Douglas-fir stand,...

Climate determines where and how forests grow. Particularly in the West, precipitation patterns regulate forest growth rates. Wet years promote "boom" vegetative conditions, while drought years promote "bust." Are managers safe in assuming that tomorrow’s climate will mimic that of the last several decades? For the last ~100 to ~150 years, climate has been warming at what appears to be an unusually rapid rate and is projected to continue into the foreseeable future. Increased temperatures are projected to lead to broad-scale alteration of storm tracks changing precipitation patterns in...

Across the drier forests of the western United States, historical fire was a natural silvicultural process--thinning stands from below, cleaning surface fuels, and maintaining fire-resilient conditions. The 20th century fire exclusion policy, although initiated with the best of intentions, has been a disaster in dry forests, converting them to high-severity fire regimes. Restoring fire-safe forests will require the use of fire or silvicultural options that mimic fire to reduce surface fuels, reduce ladder fuels, and reduce crown density, while in the process retaining the largest, most...

We studied the role of fire exclusion in the formation of striped maple (Acer pensylvanicum) understories in mixed oak (Quercus spp.) forests of Pennsylvania and the response of this species to the reintroduction of fire. Prescribed fires were applied to parts of three mixed oak stands and data from the burned and unburned portions were compared. Increment cores and basal cross sections were collected from the unburned portions to document the dates when the different species had regenerated. In all three stands, the striped maple understories originated in the 1950s and 1960s when fire...

Prescribed fire use may be effective for increasing fire resilience in young coniferous forests by reducing surface fuels, modifying overstory stand structure, and promoting development of large trees of fire resistant species. Questions remain, however, about when and how to reintroduce fire in regenerated forests, and to what end. We studied the effects of spring prescribed fires on stand structure and canopy fuel properties in 25- to 34-year old ponderosa pine forest that was planted following the Entiat wildfire in 1970. Six adjacent units were ignited over the course of four days...

The effects of different combinations of multiple, variable-intensity silvicultural treatments on fire and habitat management objectives were evaluated for a ±6,000 ha forest reserve using simulation models and optimization techniques. Our methods help identify areas within the reserve where opportunities exist to minimize conflict between the dual landscape objectives. Results suggest that most of the trees removed by silvicultural treatments designed to support fire and habitat objectives, while generating enough revenue to break-even, would be medium-sized (17-40 cm), shade-tolerant...