Treesearch

This Resource Update provides an overview of forest resources in Georgia based on an inventory conducted by the U.S. Forest Service, Forest Inventory and Analysis (FIA) program at the Southern Research Station (SRS) in cooperation with the Georgia Forestry Commission. Estimates are based on field data collected using the FIA annualized sample design and are updated yearly. The estimates presented in this update are for the measurement year 2017 with comparisons made to data reported in 2016 and prior years.

Interspecific synchrony, that is, synchrony in population dynamics among sympatric populations of different species can arise via several possible mechanisms, including common environmental effects, direct interactions between species, and shared trophic interactions, so that distinguishing the relative importance of these causes can be challenging. In this study, to overcome this difficulty, we combine traditional correlation analysis with a novel framework of nonlinear time series analysis, empirical dynamic modeling (EDM). The EDM is an analytical framework to identify causal relationshi...

Background: Recent increases in forest tree mortality should increase the abundance coarse woody detritus (CWD) and ultimately lead to increased atmospheric carbon dioxide. However, the time course of carbon release from CWD is not well understood. We compiled CWD decomposition rate-constants (i.e., k) to examine how tree species, piece diameter, position (i.e., standing versus downed), canopy openness, and macroclimate influenced k. To illustrate their implications we modeled the effect of species and position on estimates of decomposition-related carbon flux. We examined a subset of...

Gypsy moth (Lymantria dispar L.) is one of the world's worst hardwood defoliating invasive alien species. It is currently spreading across North America, damaging forest ecosystems and posing a significant economic threat. Two subspecies L. d. asiatica and L. d. japonica, collectively referred to as Asian gypsy moth (AGM) are of special concern as they have traits that make them better invaders than their European counterpart (e.g. flight capability of females). We assessed the potential distribution of AGM in Canada using two presence-only species distribution models, Maximum Entropy...

While generality is often desirable in ecology, customized models for individual species are thought to be more predictive by accounting for context specificity. However, fully customized models require more information for focal species. We focus on pest spread and ask: How much does predictive power differ between generalized and customized models? Further, we examine whether an intermediate "semi-generalized" model, combining elements of a general model with species-specific modifications, could yield predictive advantages. We compared predictive power of a generalized model applied to...

River water quality and habitats are degraded by thermal pollution from urban areas caused by warm surface runoff, lack of riparian forests, and impervious channels that transfer heat and block cool subsurface flows. This study updates the i-Tree Cool River model to simulate restoration of these processes to reverse the urban river syndrome, while using the HEC-RAS model water surface profiles needed for flood hazard analysis in restoration planning. The new model was tested in a mountain river within the New York City drinking water supply area (Sawmill, SM, Creek), and then used for base...

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...

The Demonstration of Ecosystem Management Options (DEMO) Study is an operational-scale experiment in variable-retention harvests with six installations in western Washington and Oregon. Initiated in 1994, the experiment was designed to test key assumptions underlying standards and guidelines in the Northwest Forest Plan for regeneration harvests on matrix lands. The orthogonal portion of the six-treatment design (15 and 40 percent retention in both aggregated and dispersed patterns) is unique among large-scale variable-retention experiments, allowing for independent tests of responses to...

Invasive species remain one of the greatest threats to the productivity and sustainability of agriculture, forests, prairies and wetlands (Lovett et al., 2016; Paini et al., 2016). By definition these species are alien (i.e. non-native) to some ecosystems in which they now occur. In their adventive geographic range, they lack co-evolutionary history with the native flora and fauna. As a result, hosts are bereft of specific resistance mechanisms, and no specialized co-evolved natural enemies occur to regulate pest population growth. Alien species become invasive when they cause, or are...

Urban vacancy is a persistent problem in many cities across the U.S. and globally. Vacant land greening helps improve neighborhood conditions and initiatives that transfer vacant lots to neighborhood residents can return benefits to where they are most needed. We examined one such initiative, the Chicago Large Lot Program, which allows property owners in high-vacancy areas to purchase 1–2 city-owned vacant lots on their block for $1 each. We developed a fine-scale landscape change analysis based on a visual assessment of aerial and street-level imagery. Our assessment, which included 20...