Treesearch

Key Findings Warming air temperatures will likely increase regional drying regardless of changes in precipitation, and this drying will likely increase wildfire risk across southeastern USA forests. Longer growing seasons will likely increase the risk of insect outbreak and very likely will expand the northern range of some species such as the southern pine beetle. Continued increases in metropolitan populations coupled with increase water use by forests will likely cause more frequent and severe regional and local water shortages. Despite climate and demographic derived changes, forests...

Hemlock woolly adelgid (HWA) is an exotic insect pest causing severe decimation of native hemlock trees. Extensive research has been conducted on the ecological impacts of HWA, but the exact physiological mechanisms that cause mortality are not known. Water relations, anatomy and gas exchange measurements were assessed on healthy and infested eastern (Tsuga canadensis) and Carolina (Tsuga caroliniana) hemlock trees. These data were then used in a mechanistic model to test whether the physiological responses to HWA infestation were sufficiently significant to induce changes in whole-plant...

Forest structure is strongly influenced by disturbance, agents of which can include fire, weather, mammals, annelids, fungi, insects, and increasingly with the advent of the Anthropocene, climate. Currently, climate change represents one of the broadest threats to natural systems, including forests, with the potential to directly alter forest structure and function through mechanisms such as drought induced tree mortality (Allen et al., 2010), changes in tree species distribution (Allen and Breshears, 1998; Neilson and Marks, 1994), density (Allen et al., 2010), and composition (Allen and...

We investigated the use of principal components analysis (PCA) to visualize dominant patterns and identify anomalies in a multi-year land surface phenology data set (231 m × 231 m normalized difference vegetation index (NDVI) values derived from the Moderate Resolution Imaging Spectroradiometer (MODIS)) used for detecting threats to forest health in the conterminous United States (CONUS). Our goal is to find ways that PCA can be used with this massive data set to automate the process of detecting forest disturbance and attributing it to particular agents. We briefly describe the parallel...

All components of the soil-plant-atmosphere (s-p-a) continuum are known to control berry quality in grapevine (Vitis vinifera L.) via ecophysiological interactions between water uptake by roots and water loss by leaves. The scope of the present work was to explore how the main hydraulic components of grapevine influence fruit quality through changes in liquid and gas-phase hydraulic conductance.

While jotting down some notes for this forword, I’m also thinking about how the day was spent in the upper elevations of the Bartlett Experimental Forest planning out a monitoring scheme for an early upper-slope harvest in an oak stand. The previous several weeks were spent in relocating cruise lines for some 450-500 permanent plots established in 1931-32. And it’s time to resurvey several compartments under management since the mid-50's. My associates are conducting small mammal surveys, underway for 20 years or so, in a variety of managed and unmanaged compartments. Annual breeding bird...

Aspen (Populus tremuloides) is a temperate North American tree species with a geographical distribution more extensive than any other tree species on the continent. Because it is economically important for pulp and paper industries and ecologically important for its role as a foundation species in forest ecosystems, the decline of aspen in large portions of its range is of serious concern. The availability and annotation of the black cottonwood (Populus trichocarpa) genome enables a range of high throughput sequencing approaches that can be used to understand rangewide patterns of genetic...

This study evaluated the potential effectiveness of future carbon reserve scenarios, where U.S. forest landowners would hypothetically be paid to sequester carbon on their timberland and forego timber harvests for 100 years. Scenarios featured direct payments to landowners of $0 (baseline), $5, $10, or $15 per metric ton of additional forest carbon sequestered on the set aside lands, with maximum annual expenditures of $3 billion. Results indicated that from 1513 to 6837 Tg (Teragrams) of additional carbon (as carbondioxide equivalent, CO2e) would be sequestered on U.S. timber-lands...

Although climate change will alter both soil water availability and evaporative demand, our understanding of how future climate conditions will alter tree hydraulic architecture is limited. Here, we demonstrate that growth at elevated temperatures (ambient +5 °C) affects hydraulic traits in seedlings of the deciduous boreal tree species Populus tremuloides, with the strength of the effect varying with the plant organ studied. Temperature altered the partitioning of hydraulic resistance, with greater resistance attributed to stems and less to roots in warm-grown seedlings (P < 0.02), and a...

Spatial pattern in the distribution and abundance of organisms is an emergent property of collective rates of reproduction, survival and movement of individuals in a heterogeneous environment. The form, intensity and scale of spatial patterning can be used to test hypotheses regarding the relative importance of candidate processes to population dynamics. Using 84 plots across eastern North America, we studied populations of two associated plant parasites, the invasive felted beech scale Cryptococcus fagisuga Lind. and the native Neonectria fungi, which together cause beech bark disease...