Without periodic fire, historically open-canopied, oak-dominated upland woodlands of the central and eastern United States are shifting to closed-canopied forests with increased abundance shade-tolerant typically fire-sensitive species. Once established, these encroaching species (i.e., mesophytes) hypothesized initiate a positive feedback termed mesophication where mesophytes perpetuate condit...

In historically open-canopied and fire-dependent upland oak (Quercus spp.) forests of the central eastern United States, fire exclusion is contributing to an increase in competing non-oak tree species that are often shade-tolerant fire-sensitive. As these encroach abundance declines, becoming denser will likely become cooler, moister, less flammable through a hypothesized feedback loop termed m...

The California Oak Disease and Arthropod (CODA) host index database is a compilation of information on agents that colonize or feed on oaks in California. Agents in the database include plant-feeding insects and mites, nematodes, microorganisms, viruses, and abiotic disease agents. CODA contains summarized information on hosts, agents, information sources, and the details of the host-agent inte...

Potential insect vectors for transmission of oak leaf scorch caused by Xylella fastidiosa Wells et al., in pin and red oaks in New Jersey were surveyed by placing yellow sticky card traps in tree canopies and fogging with pyrethrin insecticide during 2002-2006. Thirty-seven Cicadomorpha species were collected from 20 genera in Membracidae, Cicadellidae, Aphrophoridae, and Clastopteridae. Of th...

Wooded pastures with ancient trees were formerly abundant throughout Europe, but during the last century, grazing has largely been abandoned often resulting in dense forests. Ancient trees constitute habitat for many declining and threatened species, but the effects of secondary woodland on the biodiversity associated with these trees are largely unknown. We tested for difference in species ric...

Oaks (Quercus, Fagaceae) are the dominant tree genus of North America in species number and biomass, and Mexico is a global center of oak diversity. Understanding the origins of oak diversity is key to understanding biodiversity of northern temperate forests. A phylogenetic study of biogeography, niche evolution and diversification patterns in Quercus was performed using 300 samples, 146 specie...

Cyclic outbreaks of defoliating insects devastate forests, but their causes are poorly understood. Outbreak cycles are often assumed to be driven by density-dependent mortality due to natural enemies, because pathogens and predators cause high mortality and because natural-enemy models reproduce fluctuations in defoliation data. The role of induced defenses is in contrast often dismissed, becau...

Oak decline and related mortality have periodically plagued upland oak-hickory forests, particularly oak species in the red oak group, across the Ozark Highlands of Missouri, Arkansas and Oklahoma since the late 1970s. Advanced tree age and periodic drought, as well as Armillaria root fungi and oak borer attack are believed to contribute to oak decline and mortality. Declining trees first show ...