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Dendrochronological Assessment of Whitebark Pine Response to Past Climate Change: Implications for a Threatened Species in Grand Teton National Park
No full textOne of the keystone tree species in subalpine forests of the western United States â whitebark pine (Pinus albicaulis, hereafter whitebark pine) â is experiencing a significant mortality event (Millar et al. 2012). Whitebark pine occupies a relatively restricted range in the high-elevation ecosystems in the northern Rockies and its future is uncertain. The current decline of whitebark pine populations has been attributed to pine beetle infestations, blister rust infections, anthropogenic fire suppression, and climate change (Millar et al. 2012). Despite the knowledge that whitebark pine is severely threatened by multiple stressors, little is known about the historic capacity of this species to handle these stressors. More specifically, it is unknown how whitebark pine has dealt with past climatic variability, particularly variation in the type of precipitation (rain vs. snow) available for soil moisture, and how differences in quantity of precipitation have influenced the establishment and growth of modern stands. We propose to study the past responses of whitebark pine to paleoclimatic conditions, which would be useful to park ecologists in developing new conservation and regeneration plans to prevent the extinction of this already severely threatened high-elevation resource. The purpose of this study is to determine in great temporal and spatial detail the demographics of the current stand of whitebark pine trees in the watershed surrounding an unnamed, high-altitude pond (known informally as Whitebark Pine Moraine Pond) located approximately 3.06 miles NW of Jenny Lake in Grand Teton National Park (GTNP). The main objectives of this study were: 1.) To obtain the precise GPS locations of the current stand of whitebark pine trees in the watershed to generate a GIS map detailing their locations. 2.) To obtain increment cores of a subset of the trees in the watershed to estimate age and date of establishment for the current stand of whitebark pines, with particular attention to fire history. 3.) To analyze ring widths from core samples to identify climatic indicators that may influence the regeneration and survival of whitebark pine
Evaluating the Effects of Projected Climate Change on Forest Fuel Moisture Content
No full textUnderstanding how live and dead forest fuel moisture content (FMC) varies with seasonal weather and stand structure will improve researchersâ and forest managersâ ability to predict the cumulative effects of weather on fuel drying during the fire season and help identify acute conditions that foster wildfire ignition and high rates of fire spread. No studies have investigated the efficacy of predicting FMC using mechanistic water budget models at daily time scales through the fire season nor have they investigated how FMC may vary across space. This study addresses these gaps by (1) validating a novel mechanistic live FMC model and (2) applying this model with an existing dead FMC model at three forest sites using five climate change scenarios to characterize how FMC changes through time and across space. Sites include post-fire 24-year old forest, mature forest with high canopy cover, and mature forest affected by the mountain pine beetle with moderate canopy cover. Climate scenarios include central tendency, warm/dry, warm/wet, hot/dry, and hot/wet
Strong power and subexponential laws for an ordered list of trajectories of a Markov chain
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Exact relaxation for the semidefinite matrix rank minimization problem with extended Lyapunov equation constraint
No full textThe combinatorial inverse eigenvalue problem II: all cases for small graphs
No full textLet G be a simple undirected graph on n vertices and let S(G) be the class of real symmetric n by n matrices whose nonzero off-diagonal entries correspond to the edges of G. Given 2n - 1 real numbers \lambda_1\geq \mu_1 \geq \lambda_2 \geq \mu_2 \geq \cdots \geq \lambda_{n-1} \geq \mu_{n-1} \geq \lambda_{n-1}, and a vertex v of G, the question is addressed of whether or not there exists A in S(G) with eigenvalues \lambda_1, \ldots, \lambda_ n such that A(v) has eigenvalues \mu_1, \ldots, \mu_{n-1}, where A(v) denotes the matrix with vth row and column deleted. A complete solution can be given for the path on n vertices with v a pendant vertex and also for the star on n vertices with v the dominating vertex. The main result is a complete solution to this "\lambda, \mu" problem for all connected graphs on 4 vertices
Minimum Rank of Graphs with Loops
No full textA loop graph \mf G is a finite undirected graph that allows loops but does not allow multiple edges. The set \sym(\lG) of real symmetric matrices associated with a loop graph \lG of order is the set of symmetric matrices A=[a_{ij}]\in\Rnn such that if and only if ij\in E(\lG). The minimum (maximum) rank of a loop graph is the minimum (maximum) of the ranks of the matrices in \sym(\lG). We characterize loop graphs having minimum rank at most two (by forbidden induced subgraphs and graph complements) and loop graphs having minimum rank equal to the order of the graph. A Schur complement reduction technique is used to determine the minimum ranks of cycles with various loop configurations; we also determine the minimum ranks of complete graphs and paths with various configurations of loops. Unlike simple graphs, loop graphs can have maximum rank less than the order of the graph. We present some results on maximum rank and which ranks between minimum and maximum can be realized. Interesting open questions remain
Image-kernel (P,Q)-inverses in rings
No full textElements with equal idempotents related to their image-kernel (p,q)-inverses are characterized, and applications to perturbations, reverse order law ans communtativeity are given.