Treesearch

The tropical dry forest (TDF) biome has undergone a diversity of severe disturbances, with resulting transformations and continued pressures making this biome type one of the Earth’s most threatened. Supporting large numbers of native, often endemic species, fragments of TDF serve as important but precarious refugia. There are global efforts to restore this once extensive forest type, but the impact of TDF restoration on biodiversity and ecosystem function is poorly understood. Here, we present results from an analysis of 187 unique studies, published between January 1990 and February...

The emerald ash borer [Agrilus planipennis Fairmaire (Coleoptera:Buprestidae)] was first discovered in the United States in 2002 near Detroit, Michigan, and has spread quickly throughout the eastern United States and Canada, with isolated populations as far west as Oregon and British Columbia. Because ash trees in North America lack natural resistance to the beetle, emerald ash borer populations grew very quickly and have killed more than 100 million native ash trees. Since 2003, researchers with the U.S. Department of Agriculture, Forest Service, Northern Research Station have studied...

Different sizes and shapes of field plots relative to raster grid cells were found to negatively affect lidar augmented forest inventory. This issue is called the “change of spatial support problem (COSP)” and caused biases and reduction in estimation efficiency (precision per number of plots). For a ∼14 000 km2 study area in Oregon State, USA, we examined three different plot shapes, both fixed-radius and cluster plots, alongside grid cell sizes ranging from 5 to 70 m. Effect size varied with the magnitude of spatial mismatch between plots and raster grid cells. There was up to 15% bias...

National forest inventory (NFI) programs provide vital information on forest parameters' status, trend, and change. Most NFI designs and estimation methods are tailored to estimate status over large areas but are not well suited to estimate trend and change, especially over small spatial areas and/or over short time periods (e.g. annual estimates). Fine-scale space-time indexed estimates are critical to a variety of environmental, ecological, and economic monitoring efforts. In the United States, for example, NFI data are used to estimate forest carbon status, trend, and change to support...

Forest canopy complexity (i.e., the three-dimensional structure of the canopy) is often associated with increased species diversity as well as high primary productivity across natural forests. However, canopy complexity, tree diversity, and productivity are often confounded in natural forests, and the mechanisms of these relationships remain unclear. Here, we used two large tree diversity experiments in North America to assess three hypotheses: (1) increasing tree diversity leads to increased canopy complexity, (2) canopy complexity is positively related to tree productivity, and (3) the...

Until it was discovered in Boulder, Colorado in 2013, the invaded range of the emerald ash borer, Agrilus planipennis, in the Western Hemisphere was entirely limited to natural and urban forests of eastern North America. Subsequently, this species has expanded its range through much of the Colorado Front Range region, utilizing non-native ash, Fraxinus spp. These host trees are widely planted there in urban settings but natural forests containing ash are lacking in the region. Here we use survey data to quantify emerald ash borer regional spread across the Colorado Front Range as well as...

Propagule pressure is one of the key drivers of establishment success of non-native species, including insects. However, border interception data, which have the potential to act as a proxy for true arrival rates (i.e., propagule pressure) of insects into a country, are seldom used to predict invasions. This can be due to the limited amount of interception data in some countries, difficulties accessing such data, and when these data are available, difficulties in addressing biases caused by variation in interception probability for different taxa due to policy changes, and operational...

A new subgenus and four new species of Adelges (Hemiptera: Adelgidae) are described from Bhutan. To support their taxonomic placement, we provide a phylogeny of Adelgidae reconstructed using mitochondrial and nuclear DNA sequence data. Cassiadelges subgen. nov is distinguished by the combination of feeding on Larix secondary hosts, having tergites of the head and pronotum fused into a cephaloprothoracic shield, and having only acuminate setae on the terminal abdominal segments. Adelges (Cassiadelges) coccipus sp. nov. feeds on Larix griffithii. This remarkable species is the only known...

Society’s most vulnerable communities bear the burdens of a multitude of environmental shocks and stressors, which are increasingly likely to occur simultaneously or in quick succession. However, our understanding of where environmental risks accumulate across the United States and how determinants of multi-hazard risk vary within the country remains incomplete. This study offers a more comprehensive understanding of the national scope and underlying drivers of compounding environmental risks from five hazards (water shortage, air pollution, wildfire, flooding, and impaired water quality)...

Temperature regulates the location, frequency, and extent of irruptive forest insect herbivore outbreak cycles. Across the Pacific coastal temperate rainforest, recent outbreaks by a native defoliator, western blackheaded budworm, have impacted the greatest land area recorded since the advent of aerial detection programs and led to widespread losses of canopy leaf area and forest growth. Evidence suggests that the geographic distribution of budworm outbreaks has tracked a poleward shift in suitable temperature across the ecoregion. In this manuscript, we compile aerial observer estimates...