Treesearch

Wildland fires burn millions of forested hectares annually around the world, affecting biodiversity, carbon storage, hydrologic processes, and ecosystem services largely through fire-induced tree mortality (Bond-Lamberty et al. 2007; Dantas et al. 2016). In spite of this widespread importance, the underlying mechanisms of fire-caused tree mortality remain poorly understood, (Hood et al. 2018). Post-fire tree mortality has been traditionally modeled as an empirical function of tree defenses (bark thickness) and fire injury (crown scorch, stem char) (Ryan and Amman 1996; Woolley et al....

This work deals with a fire spreading upslope under either no-wind conditions or weak wind velocities. The surface fire propagation model developed at the University of Corsica is used; this model takes into account convective and radiative effects. The model is based on the coupling of the properties of the spreading fire with other conditions (wind, topography) and consists of a feedback effect caused by the flow induced by the fire in the presence of a positive slope. The expression of this induced wind, coupled to the propagation model gives an algebraic relationship for the rate of...

This work deals with the construction of a fire behavior model that can be easily used by people involved in firefighting or in environmental planning. The model has to provide the main physical characteristics of the fire front (rate of spread, flame tilt angle, flame height, flame length, flame temperature etc.). As this model has to be a universal one, it can be applied to any surface fire configuration without any change in the model. Keywords: physical model, radiation, convection, rate of spread.

This project involved collapsing the existing vegetation type (EVT) classes created by the LANDFIRE Program into a smaller set of structure metrics based on four key forest attributes: (1) aboveground biomass, (2) net volume of trees, (3) count of trees per acre, and (4) basal area. Our goal was to create categories that were internally homogenous with respect to these four variables and heterogeneous between categories so that the resulting categories could be effectively used in estimation, mapping, and analysis applications for forest inventory. We used k-means clustering as the main...

FIESTA (Forest Inventory ESTimation and Analysis) is an open-source, R estimation package designed for analysts who work with sample-based vegetation inventory data from the USDA Forest Service, Forest Inventory and Analysis (FIA) Program. With today’s complex questions and fast-evolving technologies, an adaptive tool is needed to efficiently process and translate multi-scale resource data into information. FIESTA was developed to augment currently available FIA tools by providing a flexible platform to accommodate unique research questions, including on-the-fly estimations from user-define...

The National Forest Inventory and Analysis (FIA) Program of the Forest Service, U.S. Department of Agriculture, estimates many important forest attributes. Post-stratification with auxiliary data is used in the estimation process to improve precision. Current procedures used by the FIA unit in the U.S. Interior West involve stratifying by predicted forest and nonforest areas. This research aims to increase the efficiency of these post-stratified estimates by exploring alternative stratification schemes. We propose five candidate schemes based on auxiliary data from different sources and...

The central dogma of molecular biology states that deoxyribonucleic acid (DNA) is transcribed to a form of ribonucleic acid known as messenger RNA (mRNA). These mRNA molecules are then translated to a string of amino acids known as a protein. These processes form the foundation of our understanding of the relationships between genotype (the sequence of nucleotides at a given locus) and phenotype (the observable characteristics resulting from the expression of a genotype in a given environment). A DNA molecule consists of four chemical residues (adenine, thymine, cytosine, and guanine)...

Tree canopies exert stronger controls than understory vegetation on hydrologic processes. Forest type, density, and dynamics (i.e., disturbance) affect the relative magnitudes of hydrologic fluxes such as interception, transpiration, evaporation, infiltration, and runoff. Although many distributed, physically based hydrologic models are capable of distinguishing overstory vs. understory influences on water resources, most assessments lack stratified canopy data and thus rely on remote sensing-based estimates of total leaf area index (LAI) (Goeking and Tarboton 2020).

Long-range planning of the water supply provided by the Colorado River requires realistic assessments of the impact of a continuation of the current drought that began in 2000, the impact of potentially extreme future droughts, and the long-term and progressive decline in watershed runoff that is caused by a warming climate. Water-supply managers want to know the maximum plausible stresses to water users so that plans for conservation, reservoir operations, and/or construction of new infrastructure can be properly developed. River managers want to know the implications of various water-supp...

Black stain root disease (BSRD) is a vascular wilt that causes mortality in several conifer species (Wagener & Mielke 1961, Harrington & Cobb 1987). It is caused by the fungus Leptographium wageneri, which can spread via root contact and is also vectored by insects (Witcosky & Hansen 1985, Witcosky et al. 1986). Douglas-fir (Pseudotsuga menziesii) is host to a specific variety of the fungus, L. wageneri var. pseudotsugae (Harrington & Cobb 1987). The fungus is vectored by two species of weevil (Pissodes fasciatus, Steremnius carinatus) and the Douglas-fir root beetle (Hylastes nigrinus)...