Treesearch

Ecosystems are changing in complex and unpredictable ways, and analysis of these changes is facilitated by coordinated, long-term research. Meeting diverse societal needs requires an understanding of what populations and communities will be dominant in 20, 50, and 100 yr. This paper is a product of a synthesis effort of the U.S. National Science Foundation funded Long-Term Ecological Research (LTER) network addressing the LTER core research area of populations and communities. This analysis revealed that each LTER site had at least one compelling story about what their site would look like...

Road networks form the basic transportation system for most of the world's inhabitants, stimulating local and regional economies. Scientific advances in recent years have revealed that this vast, growing, planetary construction boom has been occurring mostly in non-urban environments, and most aggressively in developing frontiers of tropical regions. However, even in highly urbanized countries, road networks consist mostly of roads outside of urban areas. To produce a reliable, comprehensive picture of the global road network, scientists have taken advantage of improvements in mapping...

Place-based and fieldwork learning play a key role in higher education in environmental sciences and other geospatial disciplines. We report on a study in which we evaluated a web-based virtual tour application for teaching natural resource management in fire-prone western forests in two undergraduate classes. The virtual tour uses 360°-image-based virtual scenes and pre-recorded audio commentary by a domain expert to lead participants through the Stanislaus-Tuolumne Experimental Forest where forest treatments were implemented to reduce fire hazard. We present results from assessing...

A serious concern for nurseries is the potential for Phytophthora ramorumand other Phytophthoraspecies to colonize roots without inducing aboveground symptoms in plants that then serve as cryptic reservoirs of inoculum. Episodic abiotic stresses that reduce plant water potential can compromise the host resistance to trigger disease development from root and crown infections during many Phytophthora–plant interactions. We conducted a series of experiments with root-inoculated Rhododendronplants in a potting soil mix to assess the influence of excess salt or water deficit on ramorum blight...

This study investigates whether Phytophthoraspecies may have been repeatedly introduced in natural habitats through restoration projects. Six plant species across five research locations in three counties within the San Francisco Bay Area were tested for pathogen infection of stems, roots and for rhizosphere infestation at failing restoration sites. Where possible, the same hosts were evaluated in one neighboring un-restored site disturbed by the presence of culverts, drainages or trails that also intersected the restoration site, and in a naturally regenerated and undisturbed control...

The Rough Fire started on 31 July 2015 from a lightning strike, spread to over 61,000 ha and burned parts of the Sierra and Sequoia National Forests and the Sequoia & Kings Canyon National Parks, in California. Health advisories for smoke were issued in rural areas around the fire and in urban areas of the Central Valley. PM2.5 concentrations in rural and urban areas were used to assess the air quality impacts from the fire. Before the Rough Fire, 24-h PM2.5 concentrations for all sites ranged from 1 µg m−3o 50 µgm−3. During the wildfire, the 24-h PM2.5 concentrations ranged from 2 µgm−3to...

Climate change is shifting forest tree species distributions across elevational and latitudinal gradients, and these changes are often pronounced at ecotones where species meet their climatic bounds and are replaced by other species. Using an extensive ecotone composed of lower-montane white fir (Abies concolorvar. lowiana) and upper-montane red fir (Abies magnificavar. magnifica) in the central Sierra Nevada range of California, USA, we (1) examined how the demographics of the ecotone have responded to recent climate using a field observational study and a historical dataset, (2) quantifie...

As the most remote archipelago in the world, the Hawaiian Islands are home to a highly endemic and disharmonic biota that has fascinated biologists for centuries. Forests are the dominant terrestrial biome in Hawai‘i, spanning complex, heterogeneous climates across substrates that vary tremendously in age, soil structure, and nutrient availability. Species richness is low in Hawaiian forests compared to other tropical forests, as a consequence of dispersal limitation from continents and adaptive radiations in only some lineages, and forests are dominated by the widespread Metrosiderosspecie...

Wildfire has become a larger threat to human life and property with the proliferation of homes into the wildland urban interface and warming climate. In this study we explored Alaskan homeowner preferences for wildfire risk mitigation in the wildland urban interface using discrete choice experiments to better understand the drivers of their risk mitigation actions. Estimates of willingness-to-pay for private mitigation actions are increased with wildfire risk reduction for all respondents. Willingness-to-pay for private mitigation is also positively associated with the presence of thinned...

1. Wildfire can both promote and erode resilience to future disturbances in fire-adapted ecosystems. Through a combination of past fire exclusion and climate change, fire patterns and successional trajectories are shifting with potentially negative consequences for forest resilience. In particular, high-severity short-interval reburns can lead to permanent transitions from forested to persistent non-forested ecosystems. 2. To test conditions under which wildfires promote resilience or initiate vegetation transitions we leveraged high-resolution LiDAR data, field data and a natural experimen...