Treesearch

In interior Alaska’s 115 million acres of boreal forest, white and black spruce are the dominant tree species. Climate models suggest that the region is becoming warmer and drier, resulting in declining growth of black and white spruce, according to some researchers. These drier conditions also may lead to greater risk of stand-replacing wildfires, resulting in forests dominated by birch and aspen, which are early-successional tree species. To compare long-term growth trends of the dominant coniferous and deciduous tree species, a team of researchers with the USDA Forest Service Pacific...

In recent years, many forest managers have become interested in managing forests for a wider range of objectives than previously. As an initial or intermediate treatment, variable-density thinning (VDT) can help meet objectives such as improving wildlife and plant habitats, increasing structural and compositional diversity, and enhancing aesthetic values in stands that are currently lacking spatial variability. The “skips and gaps” method of VDT is flexible, allowing for the preservation of existing desirable features. Areas that are not thinned (“skips”) will protect existing features...

Obtaining accurate tree cover maps within cities is a first step toward managing for equitable access to their ecosystem services. For example, by removing air pollutants trees contribute to fewer health impacts, and tree cover expansion could extend these benefits by targeting the most polluted areas and vulnerable populations. To support strategic tree expansion, this research created urban tree cover maps using the 2017 NASA MOD44B satellite 250m pixel product for 35 megacities, areas with large levels of pollution and vulnerable populations. Estimates of tree cover from photo-interpreta...

Since the Industrial Revolution, human activity has greatly altered the Earth's reactive nitrogen (N) cycle, leading to widespread N pollution that can have adverse effects on human health, ecological functions, and biodiversity. Quantifying the net anthropogenic nitrogen input (NANI) has proven to be a powerful method of evaluating the extent of human alteration of the N cycle on watershed and regional scales. In this study, NANI was estimated in 98% of the land area, covering 99% of the population of countries and regions around the world during the years of 1961, 1980, 1990, 2000 and...

The Lower Mississippi Alluvial Valley (LMAV) was home to about ten million hectare bottomland hardwood (BLH) forests in the Southern U.S. It experienced over 80 % area loss of the BLH forests in the past centuries and large-scale afforestation in recent decades. Due to the lack of a high-resolution cropland dataset, impacts of land use change (LUC) on the LMAV ecosystem services have not been fully understood. In this study, we developed a novel framework by integrating the machine learning algorithm, county-level agricultural census, and satellitebased cropland products to reconstruct the...

Phytoremediation has been employed as a cost-effective technique to remove the cadmium (Cd) from soil andwater in several ecosystems. However, little is known about whether intercropping the remediating plants withrice (Oryza sativa) crop could reduce Cd accumulation in rice grains. We conducted greenhouse pot and concretepond trials to explore the effects of intercropping alligator flag (Thalia dealbata, Marantaceae) on soil Cd remediation,paddy soil and microbial properties, and rice production. Our results suggest that intercropping withalligator flag significantly decreased Cd absorptio...

The invasive and widespread golden apple snail (GAS, Pomacea canaliculata) is a harmful crop pest in many parts ofAsia. The heavy use of molluscicides to control GAS could result in soil and water pollution as well as in loss ofbiodiversity. A sustainable and pollution-free control method is urgently needed to counteract this invasion. In this study,we proposed using dried and powdered GAS residue to neutralize and fertilize soils. We compared the effects of addingGAS residue (i.e., ground GAS shell and meat residue) to the effects of adding lime upon soil properties and microbes ina...

Data describing the composition of smoke are inherently multivariate and always non-negative parts of a whole. The data are relative and the information is contained in the ratios between parts of the composition. A prior analysis of smoke emissions produced from the burning of manzanita wood mixed with low-density polyethylene plastic applied traditional statistical methods to the compositional data and found no effect. The current paper applies compositional data techniques to these smoke emissions to determine if the prior analysis was accurate. Analysis of variance of the isometric...

By conservation of mass, the mass of wildland fuel that is pyrolyzed and combusted must equal the mass of smoke emissions, residual char, and ash. For a given set of conditions, these amounts are fixed. This places a constraint on smoke emissions data that violates key assumptions for many of the statistical methods ordinarily used to analyze these data such as linear regression, analysis of variance, and ttests. These data are inherently multivariate, relative, and nonnegative parts of a whole and are then characterized as so‐called compositional data. This paper introduces the field of...

During wildland fires, which include both planned (prescribed fire) and unplanned (wildfire) fires, live and dead plants may be subject to both radiative and convective heat transfer mechanisms. In this study, the pyrolysis of 14 live plant species native to the forests of the southern United States was investigated using a flat-flame burner (FFB) apparatus under three heating modes in order to mimic pyrolysis of plants during wildland fires. The heating modes were: (1) radiation-only, where the plants were pyrolyzed under a moderate heating rate of 4 °C s−1(radiative flux of 50 kW m−2);...