Chapter published in Forest and Water on a Changing Planet: Vulnerability, Adaptation and Governa... more Chapter published in Forest and Water on a Changing Planet: Vulnerability, Adaptation and Governance Opportunities: A Global Assessment Report
This study compared the sizes, spacings and properties (soil moisture, pH, nitrogen, soil arthrop... more This study compared the sizes, spacings and properties (soil moisture, pH, nitrogen, soil arthropods and VAM) of soil resource islands and bare patches in sagebrush-grass communities invaded by western juniper versus those without juniper. We analyzed 1000 surface soil samples taken from nine 50-m radius circular plots sampled in December of 1991 and May of 1992 on ‘The Island’, one of the few undisturbed areas of sagebrush-grass shrubland in Oregon. Spatial structure was interpreted from correlograms (Moran's I) and standardized semivariograms. The presence of juniper was associated with increased bare area and smaller, more widely spaced grass and sagebrush plants. Soil arthropod numbers and biomass in plots with juniper were only roughly one-fifth of those in sagebrush-grass plots in December. The dominant soil pattern in both sagebrush-grass and juniper-sagebrush-grass plots was regularly-distributed patches spanning a range of sizes and spacings. Plots with juniper had grea...
Predicting biodiversity responses to climate change remains a difficult challenge, especially in ... more Predicting biodiversity responses to climate change remains a difficult challenge, especially in climatically complex regions where precipitation is a limiting factor. Though statistical climatic envelope models are frequently used to project future scenarios for species distributions under climate change, these models are rarely tested using empirical data. We used long‐term data on bird distributions and abundance covering five states in the western US and in the Canadian province of British Columbia to test the capacity of statistical models to predict temporal changes in bird populations over a 32‐year period. Using boosted regression trees, we built presence‐absence and abundance models that related the presence and abundance of 132 bird species to spatial variation in climatic conditions. Presence/absence models built using 1970–1974 data forecast the distributions of the majority of species in the later time period, 1998–2002 (mean AUC = 0.79 ± 0.01). Hindcast models performe...
A conceptual model of Douglas-fir bark beetle (Dendroctonus pseudotsugae) dynamics and associated... more A conceptual model of Douglas-fir bark beetle (Dendroctonus pseudotsugae) dynamics and associated host tree mortality across multiple spatial and temporal scales was developed, then used to guide a study of the association between the occurrence of beetle- killed trees and factors that might render trees more susceptible to attack. Long-term records of beetle kill showed that beetle epidemics were associated
Species distribution models play a key role in creating reserves for species conservation, predic... more Species distribution models play a key role in creating reserves for species conservation, predicting the effects of ecological change, and testing ecological theory. Although many methods have been developed for models of individual species, ...
Long‐term ecological data are crucial in helping ecologists understand ecosystem function and env... more Long‐term ecological data are crucial in helping ecologists understand ecosystem function and environmental change. Nevertheless, these kinds of data sets are difficult to analyze because they are usually large, multivariate, and spatiotemporal. Although existing analysis tools such as statistical methods and spreadsheet software permit rigorous tests of pre‐conceived hypotheses and static charts for simple data exploration, they have limited capacity to provide an overview of the data and to enable ecologists to explore data iteratively, and interactively, before committing to statistical analysis. These issues hinder how ecologists gain knowledge and generate hypotheses from long‐term data. We present Ecological Distributions and Trends Explorer (EcoDATE), a web‐based, visual‐analysis tool that facilitates exploratory analysis of long‐term ecological data (i.e., generating hypotheses as opposed to confirming hypotheses). The tool, which is publicly available online, was created an...
Canadian Journal of Fisheries and Aquatic Sciences, 2000
We improved our predictions of fall chinook salmon (Oncorhynchus tshawytscha) habitat use by anal... more We improved our predictions of fall chinook salmon (Oncorhynchus tshawytscha) habitat use by analyzing spawning habitat at the spatial scale of redd clusters. Spatial point pattern analyses indicated that redd clusters in the Hanford Reach, Columbia River, were consistent in their location from 1994 to 1995. Redd densities were 16.1 and 8.9 redds·ha-1 in 1994 and 1995, respectively, and individual redds within clusters were usually less than 30 m apart. Pattern analysis also showed strong evidence that redds were uniformly distributed within the clusters where interredd distances ranged from 2 to 5 m. Redd clusters were found to occur predominantly where water velocity was between 1.4 and 2 m·s-1, water depth was 2-4 m, and lateral slope of the riverbed was less than 4%. This habitat use represented a narrower range of use than previously reported for adult fall chinook salmon. Logistic regression analysis determined that water velocity and lateral slope were the most significant pr...
Chapter published in Forest and Water on a Changing Planet: Vulnerability, Adaptation and Governa... more Chapter published in Forest and Water on a Changing Planet: Vulnerability, Adaptation and Governance Opportunities: A Global Assessment Report
This study compared the sizes, spacings and properties (soil moisture, pH, nitrogen, soil arthrop... more This study compared the sizes, spacings and properties (soil moisture, pH, nitrogen, soil arthropods and VAM) of soil resource islands and bare patches in sagebrush-grass communities invaded by western juniper versus those without juniper. We analyzed 1000 surface soil samples taken from nine 50-m radius circular plots sampled in December of 1991 and May of 1992 on ‘The Island’, one of the few undisturbed areas of sagebrush-grass shrubland in Oregon. Spatial structure was interpreted from correlograms (Moran's I) and standardized semivariograms. The presence of juniper was associated with increased bare area and smaller, more widely spaced grass and sagebrush plants. Soil arthropod numbers and biomass in plots with juniper were only roughly one-fifth of those in sagebrush-grass plots in December. The dominant soil pattern in both sagebrush-grass and juniper-sagebrush-grass plots was regularly-distributed patches spanning a range of sizes and spacings. Plots with juniper had grea...
Predicting biodiversity responses to climate change remains a difficult challenge, especially in ... more Predicting biodiversity responses to climate change remains a difficult challenge, especially in climatically complex regions where precipitation is a limiting factor. Though statistical climatic envelope models are frequently used to project future scenarios for species distributions under climate change, these models are rarely tested using empirical data. We used long‐term data on bird distributions and abundance covering five states in the western US and in the Canadian province of British Columbia to test the capacity of statistical models to predict temporal changes in bird populations over a 32‐year period. Using boosted regression trees, we built presence‐absence and abundance models that related the presence and abundance of 132 bird species to spatial variation in climatic conditions. Presence/absence models built using 1970–1974 data forecast the distributions of the majority of species in the later time period, 1998–2002 (mean AUC = 0.79 ± 0.01). Hindcast models performe...
A conceptual model of Douglas-fir bark beetle (Dendroctonus pseudotsugae) dynamics and associated... more A conceptual model of Douglas-fir bark beetle (Dendroctonus pseudotsugae) dynamics and associated host tree mortality across multiple spatial and temporal scales was developed, then used to guide a study of the association between the occurrence of beetle- killed trees and factors that might render trees more susceptible to attack. Long-term records of beetle kill showed that beetle epidemics were associated
Species distribution models play a key role in creating reserves for species conservation, predic... more Species distribution models play a key role in creating reserves for species conservation, predicting the effects of ecological change, and testing ecological theory. Although many methods have been developed for models of individual species, ...
Long‐term ecological data are crucial in helping ecologists understand ecosystem function and env... more Long‐term ecological data are crucial in helping ecologists understand ecosystem function and environmental change. Nevertheless, these kinds of data sets are difficult to analyze because they are usually large, multivariate, and spatiotemporal. Although existing analysis tools such as statistical methods and spreadsheet software permit rigorous tests of pre‐conceived hypotheses and static charts for simple data exploration, they have limited capacity to provide an overview of the data and to enable ecologists to explore data iteratively, and interactively, before committing to statistical analysis. These issues hinder how ecologists gain knowledge and generate hypotheses from long‐term data. We present Ecological Distributions and Trends Explorer (EcoDATE), a web‐based, visual‐analysis tool that facilitates exploratory analysis of long‐term ecological data (i.e., generating hypotheses as opposed to confirming hypotheses). The tool, which is publicly available online, was created an...
Canadian Journal of Fisheries and Aquatic Sciences, 2000
We improved our predictions of fall chinook salmon (Oncorhynchus tshawytscha) habitat use by anal... more We improved our predictions of fall chinook salmon (Oncorhynchus tshawytscha) habitat use by analyzing spawning habitat at the spatial scale of redd clusters. Spatial point pattern analyses indicated that redd clusters in the Hanford Reach, Columbia River, were consistent in their location from 1994 to 1995. Redd densities were 16.1 and 8.9 redds·ha-1 in 1994 and 1995, respectively, and individual redds within clusters were usually less than 30 m apart. Pattern analysis also showed strong evidence that redds were uniformly distributed within the clusters where interredd distances ranged from 2 to 5 m. Redd clusters were found to occur predominantly where water velocity was between 1.4 and 2 m·s-1, water depth was 2-4 m, and lateral slope of the riverbed was less than 4%. This habitat use represented a narrower range of use than previously reported for adult fall chinook salmon. Logistic regression analysis determined that water velocity and lateral slope were the most significant pr...
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Papers by Julia A Jones