The roots of nearly all land plants form mycorrhizal symbioses with specialized soil fungi. The mycorrhizal fungi serve as extensions of plant roots, taking up nutrients and water and transferring them to the roots. In return, the mycorrhizal fungi receive their primary energy source in the form of simple sugars from plant photosynthates translocated to the roots. Sequoiadendron giganteum forms...

LIKE MUCH OF THE WESTERN UNITED STATES, California’s forest has been severely altered by a century of fire suppression. The Sierra Nevada’s largest forest type, mixed conifer, which is primary habitat for more vertebrate species than any other Californian forest community, historically burned every 12–17 years. In 1894, John Muir wrote “The inviting openness of the Sierra woods is one of their ...

Progress on two main studies on fungal ectomycorrhizal communities in the Sierra National Forest is discussed. One study examined the short-term effects of ground fire on the ectomycorrhizal community and the other examined the ectomycorrhizal associates of snow plant (Sarcodes sanguinea). In the ground-fire study we found that a large initial reduction in ectomycorrhizal biomass is caused prim...

In southern pine seedbeds, weed control relies on the use of diphenylether herbicides (oxyfluorfen, lactofen) and selective grass herbicides (sethoxydim and fluzifop-p-butyl). A number of nurseries use a polymer to stabilize the soil after sowing. This helps keep the herbicide barrier intact and extends the preemergence activity. Weekly postemergence applications of low rates are common and hav...

Mortality was recorded annually over a 15-year period after thinning in each of three evenaged stands (one ponderosa pine and two ponderosa pine/Douglas-fir/western larch), and after individual tree selection cutting in two uneven-aged ponderosa pine stands. Highest mortality occurred in the controls in both the evenand uneven-aged stands, primarily due to suppression, while weather was the lea...

Plant growth depends upon the activity of numerous types of organisms within the environment. The recycling of nutrients in the forest floor involves the interaction of a vast diversity of bacteria, fungi, protozoa, and invertebrates. Arthropods are integral to the initial shredding of the litter, which exposes nutrients to microbial digestion. Hundreds of California species either feed directl...

Biogeographic origins of plant lineages are often reflected in species functional traits, with consequences for community assembly, diversity, and ecosystem function. The climatic and environmental conditions in which species evolved have lasting influence (legacy effects) through phylogenetic conservatism of traits that underlie community assembly and drive ecosystem processes. Legacy effects ...