Treesearch

Wild pigs (Sus scrofa) have been widely distributed by humans and significant populations now occur in oak-dominated ecosystems in California. Because they are omnivorous and forage by rooting, wild pigs have the potential to impact a wide variety of plants and animals directly by consumption and indirectly through disturbance. In 1998, we initiated a long-term study of the ecological effects of wild pigs on oak woodland ecosystems in California using multiple exclosures with paired control plots targeting four oak communities in the north and central coast region of California that vary...

Fire damage and tree characteristics of mixed deciduous oak woodlands were recorded after a prescription burn in the summer of 1999 on Mt. Hamilton Range, Santa Clara County, California. Trees were tagged and monitored to determine the effects of fire intensity on damage, recovery and survivorship. Fire-caused mortality was low; 2-year post-burn survey indicates that only three oaks have died from the low intensity ground fire. Using ANOVA, there was an overall significant difference for percent tree crown scorched and bole char height between plots, but not between tree-size classes....

Tree roots are often damaged during construction projects, particularly during trenching operations for pipeline installation. Although mechanical soil excavation using heavy equipment, such as an excavator or backhoe is considered the fastest the most economical method, it damages and destroys tree roots and can lead to unintentional tree loss, poor public relations, fines, and litigation. In sensitive areas around tree roots, soil excavation can be completed by hand although this is very slow and expensive. Alternate soil excavation methodologies are available, including a special...

Treeshelters are individual seedling protectors that can accelerate height growth of native California oaks. There is concern, however, that this growth may occur at the expense of the roots, resulting in poor long-term field performance. This study could detect no differences between protected and unprotected seedlings in shoot weight, root weight or shoot/root ratios after 4½ years, suggesting that shelters do not adversely affect balances between seedling shoots and roots. Shelters did, however, stimulate height growth and reduce initial stem diameter growth, resulting in tall narrow...

Oaks are renowned for posing problems in defining species boundaries. One example is the case of the interior live oak complex that is usually taken to include two varieties of Quercus wislizeni from the Coast Ranges of California and the Sierra Nevada, and Q. parvula var. shreveii from the central coast of California. The latter taxon was separated from Q. wislizeni, and was recognized in The Jepson Manual, but still is not fully accepted, since its morphological separation is ambiguous. In an attempt to test differentiation of these two taxa, molecular genetic analysis was carried out...

We modeled future development in rapidly urbanizing El Dorado County, California, to assess ecological impacts of expanding urbanization and effectiveness of standard policy mitigation efforts. Using raster land cover data and county parcel data, we constructed a footprint of current development and simulated future development using a modified stochastic flood-fill algorithm. We modeled combinations of constraints from the 1996 County General Plan and parcel data—slope, stream buffers, oak canopy retention, existing development, public ownership, regional clustering, and acquisition...

This conference on "Oaks in California's Changing Landscape" is a most timely and important conference at a critical time in California. Having been born and raised in California, I have never known a time when this landscape was not changing. And, usually not for the better if you care about our natural environment, as I do. But, today it is changing at an ever-increasing rate and scale, and the forces of restoration and conservation of that natural landscape seem even more outpaced by those of development and degradation.

Twenty species of oak (Quercus) are known from California. The white oak group is the most diverse, and includes a complex of scrub oak species that are often encountered in chaparral, mixed forest and desert margin habitats. The Protobalanus group (e.g., Quercus chrysolepis) is a unique and distinctive clade of western North American species that appears to be most closely related to the white oak group. Within the white oaks and red oaks (black oaks), the majority of California species do not have obvious, close relationships to species outside of the region. In addition, these species...

The status and prospects of oaks—those native to California and the many elsewhere—are insufficiently known, despite historical volumes of work done in the past and more ongoing today. That globally there is a blistering diversity of oaks in different environments, and put to distinct uses, is beyond dispute. Less agreed upon, though, is their complex history and the variation in the nature of the oak woodland. Because oak landscapes are so varied, and yet so ubiquitous, perhaps their one single shared feature worldwide is a multiplicity of uses. If individual oaks are cherished, and...

Fire-return intervals were studied on six 1.4-ha plots in a 2,070-ha study area in the Dinkey Creek watershed. Stumps in mixed-conifer forest were examined for fire scars created from 1771 to 1994, with 1873 chosen as the end of the pre-Euro-American settlement period because the rate of fire events decreased on most plots after about that year. Mean intervals from 1771 to 1873 ranged from 3.19 to 5.44 years, maximum intervals ranged from 6 to 12 years, and minimum intervals ranged from 1 to 2 years. Differences between plot means were not significant during that period, and the data...