Treesearch

The monitoring studies carried out in the southern Romanian Carpathians (Retezat and Bucegi - Piatra Craiului Mts) provide a scientific support for long term ecosystem research (LTER). Their general objective is to characterize the air pollution and its potential effects upon forest ecosystems' status and biodiversity in close connection with climatic changes. Two monitoring networks were placed in selected forest ecosystems for each LTER site (11 plots in Retezat and 22 plots in Bucegi - Piatra Craiului, respectively). Both in Retezat and Bucegi - Piatra Craiului Mts, the distribution of...

Climate change and air pollution are two of the anthropogenic stressors that require international collaboration. Influence mechanisms and combating strategies towards them have similarities to some extent. Impacts of air pollution and climate change have long been studied under IUFRO Research Group 7.01 and state of the art findings are presented at biannual meetings. Monitoring, modelling, assessment of multiple stressors, ecophysiology, and nutrient cycles have been thoroughly studied aspects of climate change and air pollution research for a long time under the umbrella of IUFRO RG...

Surface ozone concentrations are presented for four high-elevation sites along a northesouth transect along the spine of the White Mountains and a fifth site located at lower elevation approximately 15 km to the west on the floor of the Owens Valley. The ozone data, which were collected from mid-June through mid-October of 2009, include results from two sites, White Mountain Summit (4342 m elevation) and Barcroft Station (3783 m), that are believed to be higher in elevation than any previously investigated sampling locations in North America. Average daily ozone values from the five...

Escape from natural enemies is a widely held generalization for the success of exotic plants. We conducted a large-scale experiment in Hawaii (USA) to quantify impacts of ungulate removal on plant growth and performance, and to test whether elimination of an exotic generalist herbivore facilitated exotic success. Assessment of impacted and control sites before and after ungulate exclusion using airborne imaging spectroscopy and LiDAR, time series satellite observations, and ground-based field studies over nine years indicated that removal of generalist herbivores facilitated exotic...

Individual cuttings from five shrub species were burned over a flat-flame burner under wind conditions of 0.75–2.80 m s–1. Both live and dead cuttings were used. These included single leaves from broadleaf species as well as 3 to 5 cm-long branches from coniferous and small broadleaf species. Flame angles and flame lengths were determined by semi-automated measurements of video images. Additional data, such as times and temperatures corresponding to ignition, maximum flame height and burnout were determined using video and infrared images. Flame angles correlated linearly with wind...

Ecosystem management requires an understanding of how landscapes vary in space and time, how this variation can be affected by management decisions or stochastic events, and the potential consequences for species. Landscape trajectory analysis, coupled with a basic knowledge of species habitat selection, offers a straightforward approach to ecological risk analysis and can be used to project the effects of management decisions on species of concern. The fisher (Martes pennanti) occurs primarily in late-successional forests which, in the Sierra Nevada mountains, are susceptible to high-inten...

Interest in location-specific climate projections is growing. To facilitate the communication of these data, we provide here an example for how to present climate information relevant at the scale of a national forest. We summarize some of the latest data on climate change projections and impacts relevant to eastern California, from the global scale to the state level, then focus on the Sierra Nevada, and finally the Inyo National Forest. Most climate models project increased temperatures and reduced snow cover across most of the Sierra Nevada, potentially causing water shortages and...

Phytophthora ramorum was detected on grand fir in 2003 and 2005 in a Christmas tree plantation near Los Gatos, CA, in association with infected California bay laurel. Isolates derived from stem lesions were used to inoculate grand fir seedlings in two tests. Isolations from lesions on inoculated plants were positive for P. ramorum in both tests. This work provides the completion of Koch’s postulates to establish grand fir as a host of P. ramorum. The potential for grand fir to be infected within its native range is unknown.

In 2005 and 2006, white fir and Douglas-fir growing in a Christmas tree plantation near Los Gatos, CA, under a black walnut tree infected with mistletoe tested positive for Phytophthora ramorum, the cause of Sudden Oak Death. Isolation from a symptomatic mistletoe inflorescence stalk was positive for P. ramorum. In 2007, fresh mistletoe leaves, stems, inflorescence stalks, and berries were inoculated with a zoospore suspension of the mistletoe isolate. All of the plant parts developed symptoms, and P. ramorum was isolated from each of them. This is the first report of an infection of a...

Although tanoak (Notholithocarpus densiflorus syn. Lithocarpus densiflorus) is the species most affected by the introduced pathogen Phytophthora ramorum, with demonstrable risk of extirpation, little is known about the origin, range or structuring of the tree's susceptibility. We examined variation in resistance to P. ramorum using a wound inoculation assay of detached leaves from trees at five geographically separated sites, and a non-wound inoculation assay on twigs from trees at two sites. The structure of variation in resistance was compared to the structure at nine nuclear microsatelli...