Treesearch

Aims: Species distributions are hypothesized to be underlain by a complex association of processes that span multiple spatial scales including biotic interactions, dispersal limitation, fine‐scale resource gradients and climate. Species disequilibrium with climate may reflect the effects of non‐climatic processes on species distributions, yet distribution models have rarely directly considered non‐climatic processes. Here, we use a Joint Species Distribution Model (JSDM) to investigate the influence of non‐climatic factors on species co‐occurrence patterns and to directly quantify the...

Premise of the Study: Changing climates are expected to affect the abundance and distribution of global vegetation, especially plants and lichens with an epiphytic lifestyle and direct exposure to atmospheric variation. The study of epiphytes could improve understanding of biological responses to climatic changes, but only if the conditions that elicit physiological performance changes are clearly defined. Methods: We evaluated individual growth performance of the epiphytic lichen Evernia mesomorpha, an iconic boreal forest indicator species, in the first year of a decade-long experiment...

In the past decade, urban tree canopy cover goals and tree-planting initiatives have proliferated among local governments and nonprofit organizations across the globe. While research has documented many benefits new trees will provide, less has considered whether active participation of city residents in urban forestry activities might also benefit urban neighborhoods. This paper examines nonprofit tree-planting programs in four cities in the Midwestern and Eastern United States to determine whether and to what extent neighborhood participation in a nonprofit tree-planting project might...

The effects of ecosystem degradation are pervasive worldwide and increasingly concerning under the present context of global changes in climate and land use. Theoretical studies and empirical evidence increasingly suggest that drylands are particularly prone to develop nonlinear functional changes in response to climate variations and human disturbance. Precipitation-use efficiency (PUE) represents the ratio of vegetation production to precipitation and provides a tool for evaluating human and climate impacts on landscape functionality. Holm oak (Quercus ilex) woodlands are one of the most...

To understand mechanisms of long-term hydrological and biogeochemical recovery after forest disturbance, it is important to evaluate recovery times (i.e., time scales associated with the return to baseline or predisturbance conditions) of stream runoff and nitrate concentration. Previous studies have focused on either the response of runoff or nitrate concentration, and some have specifically addressed recovery times following disturbance. However, controlling factors have not yet been elucidated. Knowing these relationships will advance our understanding of each recovery process. The...

Most fields of study have introductory textbooks with the word "principles" in the title: "Principles of Economics," "Principles of Ecology," and many others. The principles explained in these textbooks are the core unifying and ordering concepts for their respective fields. They provide a frame of reference for students who are new to the field and taking the first steps toward mastering it. The abundance of "principles" textbooks and long history of the use of core principles in education suggest that a clear set of unifying principles may be a useful way to teach students how to...

Accurate measurements of natural resources are a prerequisite for resource assessment. Demetrios Gatziolis, a scientist with the USDA Forest Service Pacific Northwest Research Station, and his colleagues with Washington State University developed and tested protocols for using structure-from-motion photogrammetry to obtain data that can be used to construct 3-dimensional (3-D) representations of trees, other vegetation, and down wood. This type of photogrammetry is a remote-sensing technique based on a sequence of digital images or video footage. Gatziolis and his colleagues focused on...

Notable in this current resource bulletin is relative stability of forest land and timberland acreage and increasing maturity of the trees and stands that comprise it. Virginia’s total land area is 27.4 million acres, 16.1 million (58.7 percent) of which are forested according to the results of the latest forest inventory completed in 2016. This current estimate confirms that Virginia’s forest land area has remained stable for at least the past two decades. The previous three, 5-year cycles of FIA data collection under the annualized forest inventory have estimates of forest land acreage...

The US National Greenhouse Gas Inventory uses the component ratio method (CRM), a volume conversion approach that incorporates models for tree biomass components, for forest carbon assessments. However, the performance of the CRM relative to other methods, as well as influences on its accuracy and precision, must be evaluated. We constructed a data-driven CRM (n-CRM), used it to predict total tree and component biomass for six US tree species, and compared this approach to a reference allometric model. We also assessed the influence of size, crown dynamics, and stem growth on the performanc...

Estimating the current status and future trends of carbon (C) stocks and stock changes in forests of the northeastern United States is desired by policy makers and managers as these forests can mitigate climate change through sequestration of atmospheric carbon dioxide (CO2). We developed C flux matrix models using tree and stand variables by tree diameter class and stand age class to compare size-structured models with age-structured models in their capacity to predict forest C dynamics that are central to policy decisions. The primary control variables for the C flux matrix models...