48 research outputs found
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Habitat relationships of birds and young-growth Douglas-fir in northwestern California
Ninety-one species of birds were surveyed in grass/forb, early and late shrub/sapling, pole, and medium sawtimber stages of young-growth Douglas-fir in northwestern California; patterns of bird distribution and abundance were related to habitat conditions and even-age silvicultural treatments. Seven species (band-tailed pigeon, western wood pewee, dusky flycatcher, western bluebird, fox sparrow, purple finch, and evening grosbeak) have probably increased in population size or distribution since extensive clearcutting in the study area began in the early 1950's. Six species (Hammond's flycatcher, chestnut-backed chickadee, red-breasted nuthatch, brown creeper, golden-crowned kinglet, and hermit warbler) are restricted to forest stages and probably have decreased in population size or distribution. Abundances of various species were associated with presence of a forest overstory, hardwood stem density, deciduous foliage volume, height and patchiness of shrub cover, number plant species, and snag density. Slope angle and distance to permanent water or to the next nearest similar habitat type explained some variation in abundance of a few species. The grass/forb stage had the lowest number of bird species and lowest total density, while the late shrub/sapling stage had the highest; species composition varied markedly across the young-growth stages. Cluster analysis defined Shrub stage specialists and forest stage Specialists. Seasonal patterns of permanent resident species suggested that the shrub stage specialists are most limited in distribution during winter, and that their winter distributions may reflect optimal ("source") habitat. In contrast, forest stage specialists showed no seasonal changes of distribution, or were more restricted in distribution during the breeding season. All phases of the clearcutting system, including site preparation, stocking control, intermediate treatments, and final harvest, greatly affect stand conditions. No one stand condition, young-growth stage, or silvicultural treatment provided best habitat for all bird species. Simplification of forest stand structure by reduction or elimination of hardwoods, snags, and large diameter softwoods, could lead to low within-stand but high between-stand diversity of vegetation and bird assemblages. Even-age silvicultural systems, however, can integrate management objectives for timber production and bird habitat
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Activity-specific ecological niche models for planning reintroductions of California condors (Gymnogyps californianus)
Ecological niche models can be a useful tool to identify candidate reintroduction sites for endangered species but have been infrequently used for this purpose. In this paper, we (1) develop activity-specific ecological niche models (nesting, roosting, and feeding) for the critically endangered California condor (Gymnogyps californianus) to aid in reintroduction planning in California, Oregon, and Washington, USA, (2) test the accuracy of these models using empirical data withheld from model development, and (3) integrate model results with information on condor movement ecology and biology to produce predictive maps of reintroduction site suitability. Our approach, which disentangles niche models into activity-specific components, has applications for other species where it is routinely assumed (often incorrectly) that individuals fulfill all requirements for life within a single environmental space. Ecological niche models conformed to our understanding of California condor ecology, had good predictive performance when tested with data withheld from model development, and aided in the identification of several candidate reintroduction areas outside of the current distribution of the species. Our results suggest there are large unoccupied regions of the California condor’s historical range that have retained ecological features similar to currently occupied habitats, and thus could be considered for future reintroduction efforts. Combining our activity-specific ENMs with ground reconnaissance and information on other threat factors that could not be directly incorporated into empirical ENMs will ultimately improve our ability to select successful reintroduction sites for the California condor.Keywords: Reintroduction, California condor, Endangered species, Habitat, MAXENT, Ecological niche model, Activity-specific nich
Projected changes in diverse ecosystems from climate warming and biophysical drivers in northwest Alaska
EcoQBNs: First Application of Ecological Modeling with Quantum Bayesian Networks
A recent advancement in modeling was the development of quantum Bayesian networks (QBNs). QBNs generally differ from BNs by substituting traditional Bayes calculus in probability tables with the quantum amplification wave functions. QBNs can solve a variety of problems which are unsolvable by, or are too complex for, traditional BNs. These include problems with feedback loops and temporal expansions; problems with non-commutative dependencies in which the order of the specification of priors affects the posterior outcomes; problems with intransitive dependencies constituting the circular dominance of the outcomes; problems in which the input variables can affect each other, even if they are not causally linked (entanglement); problems in which there may be >1 dominant probability outcome dependent on small variations in inputs (superpositioning); and problems in which the outcomes are nonintuitive and defy traditional probability calculus (Parrondo’s paradox and the violation of the Sure Thing Principle). I present simple examples of these situations illustrating problems in prediction and diagnosis, and I demonstrate how BN solutions are infeasible, or at best require overly-complex latent variable structures. I then argue that many problems in ecology and evolution can be better depicted with ecological QBN (EcoQBN) modeling. The situations that fit these kinds of problems include noncommutative and intransitive ecosystems responding to suites of disturbance regimes with no specific or single climax condition, or that respond differently depending on the specific sequence of the disturbances (priors). Case examples are presented on the evaluation of habitat conditions for a bat species, representing state-transition models of a boreal forest under disturbance, and the entrainment of auditory signals among organisms. I argue that many current ecological analysis structures—such as state-and-transition models, predator–prey dynamics, the evolution of symbiotic relationships, ecological disturbance models, and much more—could greatly benefit from a QBN approach. I conclude by presenting EcoQBNs as a nascent field needing the further development of the quantum mathematical structures and, eventually, adjuncts to existing BN modeling shells or entirely new software programs to facilitate model development and application
Metrics for evaluating performance and uncertainty of Bayesian network models. Ecological Modelling 230
a b s t r a c t This paper presents a selected set of existing and new metrics for gauging Bayesian network model performance and uncertainty. Selected existing and new metrics are discussed for conducting model sensitivity analysis (variance reduction, entropy reduction, case file simulation); evaluating scenarios (influence analysis); depicting model complexity (numbers of model variables, links, node states, conditional probabilities, and node cliques); assessing prediction performance (confusion tables, covariateand conditional probability-weighted confusion error rates, area under receiver operating characteristic curves, k-fold cross-validation, spherical payoff, Schwarz' Bayesian information criterion, true skill statistic, Cohen's kappa); and evaluating uncertainty of model posterior probability distributions (Bayesian credible interval, posterior probability certainty index, certainty envelope, Gini coefficient). Examples are presented of applying the metrics to 3 real-world models of wildlife population analysis and management. Using such metrics can vitally bolster model credibility, acceptance, and appropriate application, particularly when informing management decisions. Published by Elsevier B.V
Limnology, Vegetation, and Classification of Coast Range Slump-formed Ponds
Northwest Science, Vol. 64. No. 1, 199
Characterizing Species at Risk I: Modeling Rare Species Under the Northwest Forest Plan
The Northwest Forest Plan in the Pacific Northwest, United States includes directives for survey and site protection of hundreds of rare species across many taxonomic classes. To help direct survey activities, prioritize sites, and stand conditions for conservation of these species, I developed Bayesian belief network (BBN) models of habitat relationships and multiple stressors predicting presence of 12 rare species, and I present an example of predicting presence and absence of a rare fungus. The BBN models are developed along a rigorous process of expert judgment, peer review, reconciliation, accuracy testing, and incremental updating with known site data and validation data. Management implications of prediction errors are discussed
A Journal of Attempts to Induce and Work with Lucid Dreams: Can You Kill Yourself while Lucid?
Following is a narrative of my attempts to create lucid dreams and my experiments with the lucid dream state.I cite my journal notes I had kept during that time period
The Quandaries and Promise of Risk Management: A Scientist’s Perspective on Integration of Science and Management
Traditional risk analysis, such as through the use of decision trees, entails depicting (1) a set of alternative decisions or decision pathways based on a specified risk attitude of the decision-maker, (2) the response of the system of interest and associated probabilities, and (3) values (or utilities) of each outcome and expected values of each possible decision. Best decisions are then identified as those with the lowest expected cost or highest expected benefit values. For two decades, I have worked in risk analysis on both sides of the management/ research fence in a federal land-management agency in areas of wildlife and ecosystem conservation (e.g., Marcot et al. 2006). I can attest that this classical risk-management framework, as applied to public land and natural resource management, just doesn’t work as portrayed in the textbooks
Unique Songs of African Wood-Owls (Strix woodfordii) in the Democratic Republic of Congo
Statistical analysis of African Wood-Owl Strix woodfordii song spectrograms suggest a significantly different song type in Democratic Republic of Congo (DRC), central Africa, than elsewhere in eastern or southern Africa. Songs of DRC owls tend to be consistently shorter in duration and more monotone in overall frequency range. The first note is either absent or is very soft and slightly lower in frequency than the second note in DRC owls, compared with the first note being prominent, loud, and much higher in frequency than the second note in owls found elsewhere. Also, male owls in DRC sing at a higher frequency than do male owls elsewhere. Results from this study should be considered tentative working hypotheses, given the small sample size of song recordings available. Further study is needed to determine consistency of these findings, and the biogeographic scope and behavioral and taxonomic context of any such differences