Treesearch

Although California black oak, tanoak, and Pacific madrone are the principal hardwood species in the forest zone of California and Oregon and are key components of many plant communities, their seed production, regeneration, and early growth requirements have received little study. Information is presented on seed production, storage, and germination, and on the density, survival, and growth of three types of hardwood reproduction: seedlings, seedling-sprouts, and root-crown sprouts. Many trials showed that establishing planted seedlings in conventional sunlit plantations is difficult....

Increased use of heavy equipment and more frequent entry into forest stands has increased the potential for soil compaction and decreased productivity. We examined compaction and tree growth relationships on three California soils of contrasting textures (clayey, loamy, and sandy loam) on plots from which the organic soil horizon had been removed. Compacted and noncompacted treatments were compared. Changes in bulk density (Db), soil strength, and total porosity, measured during the growing season, were greatest in the 15- to 30-cm depth at all sites. Bulk density increases were greatest...

Abstract - Stemflow is the portion of rainfall which, having been intercepted by the forest canopy, reaches the ground by running down the stems of trees. Stemflow volumes from coast redwood, Douglas-fir, and tanoak were collected from January 2000 to April 2001 in the Caspar Creek Watershed in Mendocino County, California. Average funneling ratios reveal a greater contribution to stemflow from the crowns of tanoak and Douglas-fir trees than from those of redwood trees. An in situ bark texture experiment designed to isolate the stem from the crown was conducted on one tree of each species....

Significant channel aggradation events have occurred in numerous coastal northern California watersheds over the past 50 years, leaving lasting impacts on stream channel morphology and habitats. Our study focuses on sediment movement and channel morphology following large aggradation events and specifically focuses on the relationship between volume of stored sediment and bed material transport rates

Systemic endophytic fungi in agronomic and turf grasses are well known for conferring increased resistance to herbivores and to abiotic stresses, such as drought, and increasing competitive abilities. Many native grasses also harbor high frequencies of the asexual and vertically-transmitted endophyte, Neotyphodium. In Festuca arizonica (Arizona fescue), frequency of Neotyphodium-infected plants is often high, but variable, within and among populations. However, Neotyphodium infections in native Arizona fescue, unlike infected agronomic grasses, do not increase resistance to herbivores, do...

Knowledge of biomass components and fuel characteristics of southern California chaparral plant communities is important for planning prescribed fires, suppressing wildfires, managing the fire regime, and understanding the ecological interactions between fire and chaparral community development and succession. To improve our understanding of the relationship between fuels and fire behavior in chaparral, biomass and fuels were sampled on sites spanning a broad geographic range, as well as a range in age, species composition, and productivity. Total aboveground biomass of chaparral stands...

Postfire grass seeding as an attempt at erosion control on chaparral slopes has been a common practice for decades. Annual ryegrass (Lolium multiflorum) has been most frequently used. Critics point out that ryegrass can suppress native species and may reduce shrub seedling survival. In 1986, we began investigating the impacts of seeded ryegrass on chaparral regeneration. We gathered prefire vegetation data on sites scheduled to be burned in wildfire-intensity prescribed fires. After four prescribed fires and a wildfire, half of the vegetation plots at each site were seeded with annual...

Catastrophic wildfires can set the stage for massive postfire erosion and sedimentation in southern California chaparral ecosystems with the onset of heavy winter rainstorms. As a mitigation measure, land managers have typically used grass seeding as a standard emergency rehabilitation technique. However, the effectiveness of grass seeding as a watershed protection practice remains uncertain. To address this problem, we conducted field experiments on southern California chaparral-covered hillsides involving burning and seeding to quantify the magnitude of postfire hillslope erosion and the...