Treesearch

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...

Background: Longleaf pine (Pinus palustris Mill.) seedlings have a morphological "grass stage" that is considered to be an adaptation to frequent surface fire regimes. However, fire can kill longleaf pine seedlings and thus may play an important role in longleaf pine regeneration dynamics. We used a prescribed burn simulation tool designed to treat individual grass stage longleaf pine seedlings with controlled delivery of fire treatments and then measured survival and growth responses through two growing seasons. Naturally regenerated grass stage longleaf pine seedlings were randomly...

In this study, we estimated the respective contributions of precipitation and reference evapotranspiration (ET0) to annual SPEI-3 (3-month Standardized Precipitation- Evapotranspiration Index) anomalies over southwest China (SWC) using numerical experiments. Results show that the dominant factor (i.e., precipitation or ET0) for the dryness/wetness anomalies during 1961–2012 existed due to inter-annual and interdecadal changes over SWC, which indicates the underlying mechanisms of dry/wet conditions have changed. On the other hand, we calculate the dryness/wetness sensitivity to precipitatio...

Aim: Much is known about the elevational diversity patterns of native species and about the mechanisms that drive these patterns. A similar level of understanding is needed for non-native species. Using published data, we examine elevational diversity patterns of non-native plants and compare the resulting patterns with those observed for native plants. Location: Global. Methods: We compiled data from 65 case studies on elevational diversity patterns of non-native plants around the world (including 32 cases in which both non-native and native plants were sampled). We compared the elevationa...

Weather is an important factor that determines smoke development, which is essential information for planning smoke field measurements. This study identifies the synoptic systems that would favor to produce the desired smoke plumes for the Fire and Smoke Model Evaluation Experiment (FASMEE). Daysmoke and PB-Piedmont (PB-P) models are used to simulate smoke plume evolution during the day time and smoke drainage and fog formation during the nighttime for hypothetical prescribed burns on February 5-8, 2011 at the Stewart Army Base in the southeastern United States. Daysmoke simulation is...

Improved understanding of the physiological mechanisms of tree mortality following fires is important with the predicted increase in wildfires under climate change, as well as continued use of prescribed fire for forest management. Disruption of water transport in the xylem from exposure to the heat plume of a fire has been hypothesized as a mechanism of delayed tree mortality. This heat plume rapidly increases vapor pressure deficit in the canopy, increasing transpiration and tension on the xylem causing cavitation, thus reducing water transport and leading to eventual tree death. We...