Treesearch

Outbreaks of conifer bark beetles in Europe and North America have increased in scale and severity in recent decades. In this study, we identify existing fossil records containing bark beetle remains from the end of the Last Glacial Maximum (~14,000 cal. yr BP) to present day using the online databases Neotoma and BugsCEP and literature searches, and compare these data with modern distribution data of selected tree-killing species. Modern-day observational data from the Global Biodiversity Information Facility (GBIF) database was used to map recorded distributions from AD 1750 to present...

As climate changes, locally adapted tree populations may become maladapted to the sites in which they presently occur. When natural adaptive processes are insufficient for populations to keep pace with changing climate, human‐assisted relocation of genotypes (assisted gene flow) may be a useful tool for maintaining forest resilience. While existing empirical evidence provides insight into the potential outcomes and consequences of assisted gene flow, its applicability to large‐scale plantings needs to be evaluated. We conducted a test of assisted gene flow in the context of operational...

This study uses individual survey data to investigate the impact of information about hiking destinations on estimated wilderness values in a spatial context. The data is derived from a revealed preference survey of backcountry visitors who responded to questions about their recreation behavior in the San Jacinto Wilderness of southern California. Two GIS data layers are developed showing spatial representations of non-market values derived from a Kuhn- Tucker demand model, with and without destination information. Each pixel in each data layer contains an estimate of the recreation value...

Forest monocultures are generally considered to alter the microbial community, reduce soil fertility, and presumably reduce forest productivity compared to mixed species in plantations or mixed species in natural stands. As the mechanisms of alteration of soils by monocultures have not been elucidated very well, we compared indicators of stand productivity and soils in three forest types all growing on the same soils that developed under the natural forests of the Maoershan Forest Farm in northeastern China. The three forest types were a planted monoculture of Larix plantation but where...

In ecosystems invaded by non-native plants invasion effects are often spatially variable, and this variability is difficult to capture via plot-scale sampling. We used airborne high-resolution LiDAR (Light Detection and Ranging) to generate spatially explicit and contiguous information on hydrological effects of invasive trees (Prosopis pallida (Humb. & Bonpl. ex Willd.) Kunth). We developed regression relationships between LiDAR metrics (i.e., ground elevation and tree canopy height) and plot-scale measurements of vegetation stem water δ18O, to assess groundwater use, and transpiration...

1. In response to contemporary changes in climate, many tree species are shifting upslope to find favorable habitat. In the case of obligate ectomycorrhizal species, seedling growth above upper treeline depends on fungal spore availability. In the mountain ranges of the Great Basin, a recent shift in tree species stratification has been recorded, with limber pine (LP, Pinus flexilis) leapfrogging above the ancient bristlecone pine (BCP, Pinus longaeva) forest and establishing above current treeline. 2. We compared the ability of LP and BCP to interact with soil spore banks collected at...

Conservation across human‐dominated landscapes requires an understanding of the social and ecological factors driving outcomes. Studies that link conservation outcomes to social and ecological factors have examined temporally static patterns. However, there may be different social and ecological processes driving increases and decreases in conservation outcomes that can only be revealed through temporal analyses. Through a case study of the invasion of Falcataria moluccana in Hawaii, we examined the association of social factors with increases and decreases in invader distributions over...

Heat and mass transfer are important processes associated with wildland fire. Both radiant and convective heat transfer are important processes with convection often being the dominant mechanism. Unlike radiation, there is no direct method of measuring convection. Since convective heat transfer is governed by the fluid flow, understanding the fluid flow provides good understanding on the convective heat transfer. In fluid mechanics, flow visualization is a common methodology used to understand flow characteristics. Schlieren imagery is a common flow visualization technique which captures...

Summary Brassinosteroids have been implicated in the differentiation of vascular cell types in herbaceous plants, but their roles during secondary growth and wood formation are not well defined. Here we pharmacologically and genetically manipulated brassinosteroid levels in poplar trees and assayed the effects on secondary growth and wood formation, and on gene expression within stems. Elevated brassinosteroid levels resulted in increases in secondary growth and tension wood formation, while inhibition of brassinosteroid synthesis resulted in decreased growth and secondary vascular...

Thirteen-year growth response of ponderosa pine to various manipulations of understory vegetation was studied to determine if a threshold of understory cover can be established for plantation productivity and whether nitrogen-fixing Ceanothus species benefit plantation growth compared to non N-fixing Arctostaphylos species, given their ability to improve site fertility. Results showed that completely controlling competing vegetation increased plantation growth, as was universally expected, but the effects of partial shrub control on plantation performance was inconsistent. We did not find...