The taxonomy of oaks (Quercus) is always a challenge because many species exhibit variable phenotypes that overlap with other species. The scrub White Oaks of California are no exception. In California, Quercus section Quercus (i.e., White Oaks) includes six species of scrub oaks plus four tree oak species. Field identification utilizes leaf traits and acorns, when available, as well as geograp...

Oaks will be most scarce on good sites (Sand~r 1977; Smith, Rosier, and Hammack 1976; Trimble 1973; Trimble and Hart 1961). The reasons are simple but basic--not enough oaks are becoming established, and those that do are not developing adequately. Oaks on poorer sites are usually good stump sprouters. Sprouts grow fast and are thus competitive, especially since on poor sites there are usually ...

into the history of our landscape, flora, and vegetation. Oaks have been among the dominant trees of eastern North American forests and woodlands for approximately 10,000 years (Abrams 1992). Between 8,000 and 3,000 years ago, oaks spread to distributions close to those we observe today (Webb 1981). The landscape between the prairies of the Great Plains and the eastern deciduous forest had by t...

We investigated within-tree population density of a new invasive species in southern California, the goldspotted oak borer, Agrilus auroguttatus Schaeffer (Coleoptera: Buprestidae), with respect to host species and the community of other borers present. We measured emergence hole densities of A. auroguttatus and other borers on the lower stem (bole) of naïve oaks at 18 sites in southern Califor...

We investigated the hydraulic properties in relation to soil moisture, leaf habit, and phylogenetic lineage of 17 species of oaks ( Quercus ) that occur sympatrically in northern central Florida (USA). Leaf area per shoot increased and Huber values (ratio of sapwood area to leaf area) decreased with increasing soil moisture of species’ habitats. As a result, maximum hydraulic conductance and ma...

Oak trees play a vital role in the ecosystem of the Wasatch Mountains of Utah, providing both food and shelter for numerous organisms. Most of the Wasatch Oaks are Quercus gambelii (deciduous scrub oaks), shedding their leaves during the harsh high elevation winters. There are several unexpected evergreen oaks which appear to be hybrids of the Wasatch scrub oaks and the evergreen oak, Quercus t...

One of the largest threats to biodiversity is land use change and habitat loss. Hollow oaks (Quercus spp. L.) are well-defined patches that are hotspots for biodiversity and red-listed species, but they are often rare and fragmented in the landscape. We investigated the effect of patch size, habitat quality, and isolation on functional groups and red-listed saproxylic beetles in hollow oaks (n ...

Background The defoliation of oaks is an urgent problem for forestry in Central Europe. During the last outbreak of the green oak leaf roller(Tortrix viridana) in 2003-2005, we observed fundamental differences in the defoliation level of individual Quercus robur trees in Germany. Some of the trees seem to be somehow “tolerant” (T oaks) against the insects grub while some seem to be conspicuousl...

Oral Kaposi's sarcoma (OKS) from Tanzanian patients (78) at Muhimbili National Hospital/Muhimbili University College of Health Sciences corresponding to approximately 10% of KS registered during 1990-2005, were diagnosed (ELISA) as HIV-infected (OAKS) (74/78) and endemic KS (4/78). Females were 69.2% (54/78) with median age 31 and males 30.8% (24/78) with median age 38. More males (50%) had sys...