Treesearch

This study examines the institutional factors that affect organizations' decisions to offer after-school nature programs. Data are from interviews of 31 staff and administrators of after-school programs in San Diego, CA. Results show support for the importance of nature education experiences in general, and that such activities are more likely to be offered if they directly support the agency's mission, if the on-site supervisor and/or a staff person has an interest or knowledge in that area, if delivery and cost issues are overcome, and if they have evidence that the children like the...

We analyzed historical timber inventory data collected systematically across a large mixed-conifer-dominated landscape to gain insight into the interaction between disturbances and vegetation structure and composition prior to 20th century land management practices. Using records from over 20 000 trees, we quantified historical vegetation structure and composition for nine distinct vegetation groups. Our findings highlight some key aspects of forest structure under an intact disturbance regime: (1) forests were low density, with mean live basal area and tree density ranging from 8-30 m2...

Many managers today are tasked with restoring forests to mitigate the potential for uncharacteristically severe fire. One challenge to this mandate is the lack of large-scale reference information on forest structure prior to impacts from Euro-American settlement. We used a robust 1911 historical dataset that covers a large geographic extent (>10,000 ha) and has unbiased sampling locations to compare past and current forest conditions for ponderosa pine and mixed conifer forests in the southern Sierra Nevada. The 1911 dataset contained records from 18,052 trees in 378 sampled transects,...

Several studies have addressed the importance of woodpeckers as ecological engineers in forests due to their excavation of cavities. Although research in green, unburned forests has identified the influence of different excavators on secondary use by cavity-dependent species, little is known about the relative importance of cavities created by woodpeckers in recently burned forests. By excavating cavities, woodpeckers create habitat for secondary cavity users that can facilitate post-fire regeneration through seed dispersal, seed germination and regulation of insect populations that affect...

Small mammals comprise an important component of forest vertebrate communities. Our understanding of how small mammals use forested habitat has relied heavily on studies in forest systems not naturally prone to frequent disturbances. Small mammal populations that evolved in frequent-fire forests, however, may be less restricted to specific habitat conditions due to the instability of these resources in time and space. We investigate how canopy cover and the volume of coarse woody debris (CWD), covariates that are considered important for small mammals, impact abundance and body mass of...

Management of smoke from prescribed fires requires knowledge of fuel quantity and the amount and composition of the smoke produced by the fire to minimize adverse impacts on human health. A five-year study produced new emissions information for more than 100 trace gases and particulate matter in smoke for fuel types found in the southern United States of America using state-of-the-art instrumentation in both laboratory and field experiments. Emission factors for flaming, smoldering, and residual smoldering were developed. Agreement between laboratory and field-derived emission factors was...

Although the arboriculture industry plants and maintains trees that remove CO2 from the atmosphere, it uses heavy-duty equipment and vehicles that release more CO2 per year than other similar-sized industries in the service sector. This study used lifecycle assessment to compare CO2 emissions associated with different decisions by arborists to the amount of CO2 sequestered over 50 years for California sycamore (Platanus racemosa) planted in Los Angeles, CA. Scenarios examined effects of equipment and vehicle choices, different operational efficiencies, amounts of irrigation water applied...

Over the period 1883–2013, recruitment of subalpine limber pine (Pinus flexilis E. James) and Great Basin bristlecone pine (Pinus longaeva D.K. Bailey) above the upper tree line, below the lower tree line, and across middle-elevation forest borders occurred at localized sites across four mountain ranges in the western Great Basin. A synchronous pulse at all ecotones occurred between 1963 and 2000 (limber pine) and between 1955 and 1978 (bristlecone pine) when pines expanded 225 m beyond forest borders. Little recruitment occurred before this interval or in the 21st century. No obvious...

Vegetation of the California Great Basin is summarized.

This study seeks to answer the question, 'Will the Million Trees LA (MTLA) programme be a CO2 sink or source?' Using surveys, interviews, field sampling and computer simulation of tree growth and survival over a 40-year period, we developed the first process-based life cycle inventory of CO2 for a large tree planting initiative (TPI). Carbon dioxide emissions and reductions were simulated for 91,786 trees planted between 2006 and 2010, of which only 33.6% were estimated to survive to 2045. Early monitoring results suggest that the MTLA programme is achieving success in terms of tree...