Treesearch

The influence of enhanced nitrogen (N) deposition on key ecosystem services provided by oak woodlands was experimentally investigated. Fertilizer was applied for 2 years to paired plots in the oak understory and adjacent open grassland. Treatments simulated four N deposition levels and effects on forage productivity, biodiversity, and soil N supply were measured. At each treatment level, understory plots received twice the N fertilizer of paired open plots to simulate a deposition hotspot effect of the oak canopy. Soils in the open had lower inorganic N concentrations than the understory...

The exhibit Puerto Rico: Gateway to Landscape proposes to explore various ways in which citizens approach the landscape, or construct it – inside and outside the city – and considers city planning, the creation of parks and natural reserves, and their interpretation. From a perspective of citizen involvement, this thematic scaffolding related to landscape and the various ways we connect to is important, not just because it is relevant in the context of today’s Puerto Rico but also because it represents an opportunity to make a conscious effort to evaluate – from an interdisciplinary...

Multispectral satellite imagery, that is, remotely sensed imagery with discrete bands ranging from visible to shortwave infrared (SWIR) wavelengths, is the timeliest and most accessible remotely sensed data for monitoring tropical forests. Given this relevance, we summarize here how multispectral imagery can help characterize tropical forest attributes of widespread interest, particularly attributes that are relevant to GHG emission inventories and other forest C accounting: forest type, age, structure, and disturbance type or intensity; the storage, degradation, and accumulation of C in...

Biological knowledge about bird focal species may be used to inform planning, habitat management, and restoration efforts, with the assumption that the implementation of these species-based recommendations will maintain and enhance healthy functioning habitats and the ecosystems services they provide. Point Blue Conservation Science in collaboration with the Natural Resources Conservation Service (NRCS) state office in California recently formed the Rangeland Watershed Initiative (RWI) to restore ecosystem function by working with ranchers on privately held hardwood rangelands in the...

Fire frequency on a blue oak (Quercus douglasii) dominated rangeland in California's southern Sierra Nevada foothills was approximately every 10 years until 1965, followed by a 30 year period of fire exclusion. This resulted in a dense tree overstory with small diameters, high crown cover, poor acorn and forage production, and limited complexity in vertical habitat structure. Tree thinning was evaluated as a treatment to restore pre-fire stand structure to these rangeland areas. Three thinning treatments were evaluated: (1) thin one-third of the standing tree basal area (resulting in a...

During 1990 to 2013, the area planted with wine grapes increased nearly 4.5 times in San Luis Obispo County. Much of this development occurred on open oak savanna with scattered oak (Quercus spp.) trees. Remnant trees are retained in some vineyards, but their value to biodiversity retention has not been quantified. During April to September 2014, at six vineyards in San Luis Obispo County, we compared echolocation activity of bats and the abundance of insects at remnant trees to locations without trees in the vineyards. The mean number of insects per night was over two times greater at...

Turkey vultures (Cathartes aura) are a ubiquitous component of California’s oak woodland faunal assemblage. Though obvious, they are one of the least studied vertebrates found in our hardwood forests. This study attempts to define the role of oak trees as nesting sites for this large avian species. Verified nest trees are evaluated to determine tree structure and morphology, tree size, cavity size and cavity volumes. Nest trees need to be large and old to develop the nest characteristics being utilized by turkey vultures. Nest trees tend to be erect with large trunk cavities that extend to...

Mature California black oak (Quercus kelloggii) trees are a keystone for many Native American cultures and support important ecological values. Black oaks depend on low-intensity, relatively frequent fires to reduce competition from conifers, yet they are also vulnerable to intense fires. Restoring mature, large canopy oaks that produce high quality acorns for tribal gatherers will depend upon reestablishing a more frequent fire regime. However, in many areas that have become overly dense, thinning treatments, out-of-season burns, and/or relatively severe fires may be needed to reopen the...

It is recognized that California Indians have stewarded the landscape for millennia. As such, the coupling of fire and culture are interrelated and interdependent in many California ecosystems including oak woodlands. Colonization and subsequent governmental fire policy mandates have disrupted the cultural use of fire, which in turn has disrupted ecological functions where those fires are absent. As society grapples with the devastating impacts of wildfires and the loss of biological diversity, many Indigenous people see traditional fire use as a key to mitigation of devastating losses...

Although medusahead (Taeniatherum caput-medusae) is one of the most dominant invasive rangeland grasses in the West, we know surprisingly little about the environmental factors that drive medusahead abundance. Understanding the conditions that influence spread dynamics is central for developing effective monitoring, prevention and control programs. We established grassland plant communities and added medusahead seed across a range of five densities (from 0 to 50,000 seeds per m2) in open grassland and oak savannah habitat. We followed plants throughout the season to understand how habitat...