Treesearch

This paper illustrates how wilderness, biodiversity, and human health are intertwined. Proceeding from the assumption that humankind is part of, rather than apart from, nature, health is re-imagined as a dynamic relationship that can best be conceived in broad ecological terms. Health, from an ecological perspective, is a measure of the wellness of the individual and the ecosystem considered together. Health, at its core, is symbiotic in nature. To make the case, seven organisms are discussed that have great potential medicinal value for humankind if only their habitats are protected and...

Numerous statistical models are employed when processing forest inventory data. These models primarily provide predicted values for attributes that are difficult and/or time-consuming to measure. In some applications, models are applied across a large geographic area, which assumes the relationship between the response variable and predictors is constant within the area. The extent to which this assumption holds for a tree height prediction modelwas evaluated at regional, ecoprovince and ecosection scales in the northeastern US. Two nonlinear regression modelswere tested, a spatially...

As part of the development of the 2011 National Land Cover Database (NLCD) tree canopy cover layer, a pilot project was launched to test the use of high-resolution photography coupled with extensive ancillary data to map the distribution of tree canopy cover over four study regions in the conterminous US. Two stochastic modeling techniques, random forests (RF) and stochastic gradient boosting (SGB), are compared. The objectives of this study were first to explore the sensitivity of RF and SGB to choices in tuning parameters and, second, to compare the performance of the two final models by...

Short rotation woody crops belonging to the genera Populus L., Salix L., Pinus L., and Eucalyptus LHer. have provided broad economic and ecological benefits throughout the world, including afforestation and reforestation along urban to rural gradients. Within the genus Populus, cottonwoods, poplars, aspens, and their hybrids (hereafter referred to as poplars) have been shown to exhibit favorable genotype × environment interactions, especially in the face of changing climates. Similar growth responses have been reported for Pinus, especially with white pine (Pinus strobus L.) in the North...

Salt tolerance of agricultural crops has been studied since the 1940, but knowledge regarding salt tolerance of woody crops is still in its initial phase. Salt tolerance of agricultural crops has been expressed as the yield decrease due to a certain salt concentration within the root zone as compared to a non-saline control. The most well-known plant response curve to salinity has been a piece-wise linear regression relating crop yield to root zone salinity. This method used the hypothesis that crops tolerate salt up to a threshold after which their yield decreases approximately linearly....

Recent warming at high latitudes has accelerated permafrost thaw, which can modify soil carbon dynamics and watershed hydrology. The flux and composition of dissolved organic matter (DOM) from soils to rivers are sensitive to permafrost configuration and its impact on subsurface hydrology and groundwater discharge. Here, we evaluate the utility of DOM composition and age as a tool for detecting permafrost thaw in three rivers (Beaver, Birch, and Hess Creeks) within the discontinuous permafrost zone of interior Alaska. We observed strong temporal controls on Δ14C content of hydrophobic acid...

Background: Refined estimation of carbon (C) stocks within forest ecosystems is a critical component of efforts to reduce greenhouse gas emissions and mitigate the effects of projected climate change through forest C management. Specifically, belowground C stocks are currently estimated in the United States' national greenhouse gas inventory (US NGHGI) using nationally consistent species- and diameter-specific equations applied to individual trees. Recent scientific evidence has pointed to the importance of climate as a driver of belowground C stocks. This study estimates belowground C...

The production of pyrogenic carbon (PyC; a continuum of organic carbon (C) ranging from partially charred biomass and charcoal to soot) is a widely acknowledged C sink, with the latest estimates indicating that ~50% of the PyC produced by vegetation fires potentially sequesters C over centuries. Nevertheless, the quantitative importance of PyC in the global C balance remains contentious, and therefore, PyC is rarely considered in global C cycle and climate studies. Here we examine the robustness of existing evidence and identify the main research gaps in the production, fluxes and fate of...

Among the various animal taxa that are have established outside their native ranges, invasions by insect species are the most numerous worldwide. In order to better understand the characteristics of insect species that make them more invasion prone, the characteristics of habitats that make them more susceptible to invasions and to understand the pathways that facilitate invasions, we compared the compositions of the native and non-native insect communities among five Pacific regions: North America, the Hawaiian Islands, mainland Japan, Ogasawara and Okinawa Islands. These regions comprise...

We used measurements from airborne imaging spectroscopy and LiDAR to quantify the biophysical structure and composition of vegetation on a dryland substrate age gradient in Hawaii. Both vertical stature and species composition changed during primary succession, and reveal a progressive increase in vertical stature on younger substrates followed by a collapse on Pleistocene-aged flows. Tall-stature Metrosideros polymorpha woodlands dominated on the youngest substrates (hundreds of years), and were replaced by the tall-stature endemic tree species Myoporum sandwicense and Sophora chrysophylla...