Treesearch

Coastal redwood (Sequoia sempervirens), the world’s tallest tree species, rehydrates leaves via foliar water uptake during fog/rain events. Here we examine if bark also permits water uptake in redwood branches, exploring potential flow mechanisms and biological significance. Using isotopic labelling and microCT imaging, we observed that water entered the xylem via bark and reduced tracheid embolization. Moreover, prolonged bark wetting (16 h) partially restored xylem hydraulic conductivity in isolated branch segments and whole branches. Partial hydraulic recovery coincided with an increase...

Primary tropical rain forests are being rapidly perforated with new edges via roads, logging, and pastures, and vast areas of secondary forest accumulate following abandonment of agricultural lands. To determine how insectivorous Amazonian understory birds respond to edges between primary rain forest and three age classes of secondary forest, we radio-tracked two woodcreepers (Glyphorynchus spirurus, N = 17; Xiphorhynchus pardalotus, N = 18) and a terrestrial antthrush (Formicarius colma, N = 19). We modeled species-specific response to distance to forest edge (a continuous variable) based...

Avian diversity in fragmented Amazonian landscapes depends on a balance between extinction and colonization in cleared and disturbed areas. Regenerating forest facilitates bird dispersal within degraded Amazonian landscapes and may tip the balance in favor of persistence in habitat patches. Determining the response of Amazonian birds to fragmentation may be hindered because many species use adjacent second growth matrices thereby limiting the applicability of island biogeography to predict species loss; alternatively, a countryside biogeographic framework to evaluate the value of regenerati...

Urban forest strategies of gradually replacing high emitters of biogenic volatile organic compounds (BVOC) with low-emitting species are being considered as voluntary or emerging control measures for maintenance of the 8-h ozone standard in the Sacramento Federal Non-Attainment Area (SFNA). We describe a regulatory modeling study demonstrating the air-quality impacts of such measures as well as of strategies that increase net canopy cover. The results indicate that changing the mix of urban trees can improve air quality. The daily reductions in ozone resulting from species replacement...

Surface ozone (O3) concentrations were measured in and around the Lake Tahoe Basin using both active monitors (2010) and passive samplers (2002, 2010). The 2010 data from active monitors indicate average summertime diurnal maxima of approximately 50–55 ppb. Some site-to-site variability is observed within the Basin during the well-mixed hours of 10:00 to 17:00 PST, but large differences between different sites are observed in the late evening and pre-dawn hours. The observed trends correlate most strongly with elevation, topography, and surface vegetation. High elevation sites with steeply...

Phytophthora tentaculata Kröber & Marwitz was described in 1993 in Germany on greenhouse-grown nursery ornamentals. It has since been found in Italy, Spain, China and the U.S. (California) causing a root and stem rot of many different plant species including nursery-grown native species used for habitat restoration. P. tentaculata is homothallic and is classified in Stamps group I which is characterized by the production of mostly paragynous antheridia, papillate sporangia and the production of both hyphal swellings and chlamydospores in culture. P. tentaculata is placed in phylogenetic...

Aim Forest regeneration data provide an early signal of the persistence and migration of tree species, so we investigated whether species shifts due to climate change exhibit a common signal of response or whether changes vary by species. Location California Floristic Province, United States; mediterranean biome. Methods We related Forest Inventory and Analysis (FIA) data from 2000−07 for 13 tree species to high-resolution climate and geographical data. Using methods from invasion ecology, we derived indices of species-specific regeneration overlap and central tendency change (range-wide...

Fire in high-elevation forest ecosystems can have severe impacts on forest structure, function and biodiversity. Using a 105-year data set, we found increasing elevation extent of fires in the Sierra Nevada, and pose five hypotheses to explain this pattern. Beyond the recognized pattern of increasing fire frequency in the Sierra Nevada since the late 20th century, we find that the upper elevation extent of those fires has also been increasing. Factors such as fire season climate and fuel build up are recognized potential drivers of changes in fire regimes. Patterns of warming climate and...

Forests are a significant part of the global carbon cycle and are increasingly viewed as tools for mitigating climate change. Natural disturbances, such as fire, can reduce carbon storage. However, many forests and dependent species evolved with frequent fire as an integral ecosystem process. We used a landscape forest simulation model to evaluate the effects of endangered species habitat management on carbon sequestration. We compared unmanaged forests (control) to forests managed with prescribed burning and prescribed burning combined with thinning. Management treatments followed...

The East Bay Regional Park District maintains the largest urban park system in the United States, comprising over 45 000 ha, and more than 1900 km of trails, with extensive forests bordering residential areas. Sudden oak death (SOD), caused by the introduced oomycete Phytophthora ramorum, was first detected in a district park in 2001. Both increased fire risk and structural failure of large trees located near sites with heavy public usage are concerns for managers. Management requires reliable data about the location and severity of the disease. To produce disease incidence and risk maps,...