Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 30 of 54
Full-Text Articles in Entire DC Network
Spatial Hyperdynamism In A Post-Disturbance Simulated Forest, Qian Wang, George Malanson
Spatial Hyperdynamism In A Post-Disturbance Simulated Forest, Qian Wang, George Malanson
George P Malanson
Spatial hyperdynamism in a post-disturbance simulated forest is studied. When the cutting rate is high and if the cutting pattern is scattered or involving a larger area, the two landscape metrics have much greater variance after cutting. After cutting the potential interaction between different species is more dynamic than that before the cutting, which can be detected from the variation of the proximity measure. These dynamics are primarily driven by the appearance and disappearance of single cell patches as colonizers temporarily occupy cells vacated by the deaths of better competitors. Boundary cells are most likely to be dynamic because their …
Structural Equation Modeling Of Dynamics Of Nitrate Contamination In Groundwater, Zhi-Jun Liu, George R. Hallberg, George P. Malanson
Structural Equation Modeling Of Dynamics Of Nitrate Contamination In Groundwater, Zhi-Jun Liu, George R. Hallberg, George P. Malanson
George P Malanson
Most research on the temporal aspect of nitrate pollution in water resources has focused on surface water. Comprehensive studies on the dynamics of nitrate in ground water are lacking, especially on a drainage basin scale and for relatively long periods of time. In this study, structural equation modeling is applied in investigating the influences of climate, hydrology, and nitrogen management in agricultural production on nitrate concentration in the Big Spring Basin, Iowa, over a 10-year period. The study shows that for given hydrogeological settings, nitrogen management practices and climate are the two most important factors that affect nitrate dynamics. The …
Post-Fire Succession In Californian Coastal Sage Scrub: The Role Of Continual Basal Sprouting., George P. Malanson, W. E. Westman
Post-Fire Succession In Californian Coastal Sage Scrub: The Role Of Continual Basal Sprouting., George P. Malanson, W. E. Westman
George P Malanson
Dominant shrub species of coastal sage scrub in coastal southern Cali- fornia are able to produce shoots from their base on a continual basis in the absence of fire or other major defoliation. As a result, each shrub becomes a population of mixed-aged branches (ramets) and extends its duration in the canopy beyond the age of any of its above-ground phytomass, reduces the incidence of senescence, and per- mits an individual (genet) to survive during long fire-free intervals. A computer sim- ulation of succession in coastal sage scrub under differing fire intervals shows that continual basal sprouting may be significant …
Effects Of Terrain On Excessive Travel Distance By Snow Avalanches, George P. Malanson
Effects Of Terrain On Excessive Travel Distance By Snow Avalanches, George P. Malanson
George P Malanson
No abstract provided.
Canadian Landform Examples; 27, Beaver Landforms, David Butler, George Malanson
Canadian Landform Examples; 27, Beaver Landforms, David Butler, George Malanson
George P Malanson
No abstract provided.
Ecological Processes And Spatial Patterns Before, During And After Simulated Deforestation, George Malanson, Qian Wang, John Kupfer
Ecological Processes And Spatial Patterns Before, During And After Simulated Deforestation, George Malanson, Qian Wang, John Kupfer
George P Malanson
Ecological processes and spatial patterns, before, during and after simulated deforestation are examined. A competition-colonization simulation, in which the primary trade offs are represented in a spatially explicit model, is used to explore the consequences of additional aspects of landscape dynamics following deforestation for plant diversity and community structure. Deforestation changes the spatial pattern of the landscape, and species respond differently because of their different dispersal abilities. The basic lessons of competition-colonization models for deforestation stand, but the ensured extinction implied by the extinction debt concept is further ameliorated as more realistic pattern-process relations are theorized.
Geomorphological Limits To Self-Organization Of Alpine Forest-Tundra Ecotone Vegetation, Yu Zeng, George Malanson, David Butler
Geomorphological Limits To Self-Organization Of Alpine Forest-Tundra Ecotone Vegetation, Yu Zeng, George Malanson, David Butler
George P Malanson
Feedback in the establishment of vegetation has been shown to produce spatial patterns that differ from the geomorphological basis for resources. The dynamics of these spatial patterns have been characterized as self-organization because local processes produce them at landscape scales. Geomorphic patterns could, however, enhance or disrupt the processes that lead to patterns and the interpretation of self-organization. A simulation model that showed such indication of self-organization at alpine forest-tundra ecotones is modified to incorporate a geomorphic feature commonly seen in this environment - solifluction steps - as an exogenous condition in the model. Analyses linking spatial patterns and rates …
Effects Of Dispersal, Population Delays, And Forest Fragmentation On Tree Migration Rates, George Malanson, David Cairns
Effects Of Dispersal, Population Delays, And Forest Fragmentation On Tree Migration Rates, George Malanson, David Cairns
George P Malanson
Examining the relation between the dispersal of seeds across landscapes and the migration of species can inform studies of processes such as invasions and response to climatic change. In this research a spatially explicit model is used to analyze the effects of dispersal probability, limits on establishment, generation time, seed crop probability, and varying proportions and patterns of landscape fragmentation on migration rate. Comparisons are made with rates inferred for migrations based on isopols of species range changes in the Holocene (20–200 km/century). The effects of the parameters on migration rate in the model are additive. Dispersal probability, related to …
Turf-Banked Terrace Treads And Risers, Turf Exfoliation And Possible Relationships With Advancing Treeline, David Butler, George Malanson, Lynn Resler
Turf-Banked Terrace Treads And Risers, Turf Exfoliation And Possible Relationships With Advancing Treeline, David Butler, George Malanson, Lynn Resler
George P Malanson
Fine-scale geomorphic/pedogenic processes at alpine treeline may facilitate the initial stages of conifer invasion of alpine tundra. Turf-banked terraces and turf exfoliation associated with solifluction may provide both the topographic protection and the seedbed necessary for conifer establishment above treeline. The morphometry, stoniness and surface penetrability of turf-banked terraces were recorded. Whereas differences among sites exist due to topographic constraints, differences in soil penetrability depend on turf exfoliation. Exfoliated turf risers are significantly more penetrable than non-exfoliated solifluction risers and adjacent treads. These penetrable microsites provide favorable conditions for seed germination. The process of turf exfoliation may play a role …
Fire History And Patterns Of Venturan Subassociations Of Californian Coastal Sage Scrub, George Malanson
Fire History And Patterns Of Venturan Subassociations Of Californian Coastal Sage Scrub, George Malanson
George P Malanson
Californian coastal sage scrub has floristically distinct subassociations with sharp boundaries in the Santa Monica Mountains. This mesoscale biogeographic pattern has been variously attributed to the timing and pattern of fire and to differences in the moisture availability on sites. An examination of the actual fire history of sites reveals that recent fire events are unlikely to have caused the observed patterns. Sites with similar fire histories are not as similar in vegetation as sites with different fire histories but similar aspect. Single short fire intervals do not result in dissimilar communities; fires are unlikely to recur with the same …
Effects Of Feedbacks And Seed Rain On Ecotone Patterns, George Malanson
Effects Of Feedbacks And Seed Rain On Ecotone Patterns, George Malanson
George P Malanson
Ecotones can be abrupt changes in vegetation on gradual abiotic gradients, such as some treelines, and so have been considered as potential indicators of response to climatic change and regulators of fluxes across landscapes. Factors of positive feedback for growth and establishment and seed rain from source areas have been suggested as playing a role in such patterns and dynamics. The effects of variation in feedback strength and seed rain on the abrupt pattern have not, however, been assessed. A spatially explicit computer simulation is used to represent an ecotone as might occur at a mountain treeline. The steepness of …
Geomorphic And Biogeographic Setting Of The Rocky Mountains; Rocky Mountain Futures; An Ecological Perspective, David Cairns, David Butler, George Malanson
Geomorphic And Biogeographic Setting Of The Rocky Mountains; Rocky Mountain Futures; An Ecological Perspective, David Cairns, David Butler, George Malanson
George P Malanson
No abstract provided.
Linear Forest Patterns In Subalpine Environments, Matthew Bekker, George Malanson
Linear Forest Patterns In Subalpine Environments, Matthew Bekker, George Malanson
George P Malanson
Studies of feedback between ecological pattern and process can benefit from the analysis of visually striking patterns, as they may reveal underlying processes and clarify the relative role of exogenous versus endogenous factors in driving vegetation change. Roughly linear forest patches are common in subalpine environments, including `hedges', `ribbon forest', and `Shimagare' or `wave regenerated forests' (waves). The influence of wind is common among these patterns, but the role of positive feedback, the most important component of self-organization in biological systems, varies. Hedges are orientated parallel to prevailing winds in several mid-latitude mountain ranges worldwide. Desiccation and ice-particle abrasion kills …
Spatial Representations Of Habitat In Competition-Colonization Models, George Malanson
Spatial Representations Of Habitat In Competition-Colonization Models, George Malanson
George P Malanson
No abstract provided.
Transverse Pattern Of Vegetation On Avalanche Paths In The Northern Rocky Mountains, Montana., George P. Malanson, D. R. Butler
Transverse Pattern Of Vegetation On Avalanche Paths In The Northern Rocky Mountains, Montana., George P. Malanson, D. R. Butler
George P Malanson
No abstract provided.
Tree-Ring Analysis And Natural Hazard Chronologies; Minimum Sample Sizes And Index Values, David Butler, George Malanson, Jack Oelfke
Tree-Ring Analysis And Natural Hazard Chronologies; Minimum Sample Sizes And Index Values, David Butler, George Malanson, Jack Oelfke
George P Malanson
No abstract provided.
Mapping, Modeling, And Visualization Of The Influences Of Geomorphic Processes On The Alpine Treeline Ecotone, Glacier National Park, Mt, Usa, Stephen Walsh, David Butler, George Malanson, Kelley Crews-Meyer
Mapping, Modeling, And Visualization Of The Influences Of Geomorphic Processes On The Alpine Treeline Ecotone, Glacier National Park, Mt, Usa, Stephen Walsh, David Butler, George Malanson, Kelley Crews-Meyer
George P Malanson
Spatially explicit digital technologies are integrated within a geographic information science (GISc) context to map, model, and visualize selected direct and indirect geomorphic processes that influence the spatial organization of the alpine treeline ecotone (ATE) in Glacier National Park (GNP), MT. GISc is used to examine alpine treeline and its biotic and abiotic controls through the application of multi-resolution remote sensing systems, geospatial information and product derivatives, and simulations of treeline spatial organization. Three geomorphic features are examined: relict solifluction terraces, evidence of nonlinearity in the development of a catena, and the locations of isolated boulders. The significance of these …
Beaver, Treefall, And Cutbank Erosion In Midwestern Rivers, David Butler, George Malanson, John Kupfer, Philip Pryde
Beaver, Treefall, And Cutbank Erosion In Midwestern Rivers, David Butler, George Malanson, John Kupfer, Philip Pryde
George P Malanson
No abstract provided.
Spatially Explicit Historical Land Use Land Cover And Soil Organic Carbon Transformations In Southern Illinois, Vineet Yadav, George Malanson
Spatially Explicit Historical Land Use Land Cover And Soil Organic Carbon Transformations In Southern Illinois, Vineet Yadav, George Malanson
George P Malanson
No abstract provided.
Woody Debris, Sediment, And Riparian Vegetation Of A Subalpine River, Montana, U.S.A, George Malanson, David Butler
Woody Debris, Sediment, And Riparian Vegetation Of A Subalpine River, Montana, U.S.A, George Malanson, David Butler
George P Malanson
No abstract provided.
Site Locations And Characteristics Of Miniature Patterned Ground, Eastern Glacier National Park, Montana, U.S.A, David Butler, George Malanson
Site Locations And Characteristics Of Miniature Patterned Ground, Eastern Glacier National Park, Montana, U.S.A, David Butler, George Malanson
George P Malanson
We examined a total of 68 sites with miniature polygonal patterned ground above treeline, along and east of the Continental Divide in Glacier National Park, Montana, USA. Patterned ground develops at three geographic site-types: convex uplands; concave mountain passes and cols; and valleyside slopes. Data were collected at each site to characterize the patterned ground morphometry. Morphometry was similar regardless of site-type, and occurrence was dependent on the presence of fine-grained material on older solifluction terraces or sorted nets.
Feedback-Driven Response To Multidecadal Climatic Variability At An Alpine Treeline, Kathryn Alftine, George Malanson, Daniel Fagre
Feedback-Driven Response To Multidecadal Climatic Variability At An Alpine Treeline, Kathryn Alftine, George Malanson, Daniel Fagre
George P Malanson
The Pacific Decadal Oscillation (PDO) has significant climatological and ecological effects in northwestern North America. Its possible effects and their modification by feedbacks are examined in the forest-tundra ecotone in Glacier National Park, Montana, USA. Tree ring samples were collected to estimate establishment dates in 10 quadrats. Age-diameter regressions were used to estimate the ages of uncored trees. The temporal pattern of establishment and survival was compared to the pattern of the PDO. A wave of establishment began in the mid-1940s, rose to a peak rate in the mid-1970s, and dropped precipitously beginning ca. 1980 to near zero for the …
An Overview Of Scale, Pattern, Process Relationships In Geomorphology; A Remote Sensing And Gis Perspective, Stephen Walsh, David Butler, George Malanson
An Overview Of Scale, Pattern, Process Relationships In Geomorphology; A Remote Sensing And Gis Perspective, Stephen Walsh, David Butler, George Malanson
George P Malanson
Satellite remote sensing and geographic information systems are emerging technologies in geomorphology. They offer the opportunity to gain fresh insights into biophysical systems through the spatial, temporal, spectral, and radiometric resolutions of remote sensing systems and through the analytical and data integration capability of GIS. The two technologies can be linked together into a synergistic system that is particularly well suited to the examination of landscape conditions through the interrelationships of scale, pattern, and process, a paradigm that has gained prominence in the fields of biogeography and landscape ecology. In this study, we apply optical and microwave remote sensing systems …
Uncovering Spatial Feedbacks At Alpine Treeline Using Spatial Metrics In Evolutionary Simulations, George Malanson, Yu Zeng
Uncovering Spatial Feedbacks At Alpine Treeline Using Spatial Metrics In Evolutionary Simulations, George Malanson, Yu Zeng
George P Malanson
No abstract provided.
Flood Frequency And The Assemblage Of Dispersal Types In Hanging Gardens Of The Narrows, Zion National Park, Utah, George P. Malanson, J. Kay
Flood Frequency And The Assemblage Of Dispersal Types In Hanging Gardens Of The Narrows, Zion National Park, Utah, George P. Malanson, J. Kay
George P Malanson
No abstract provided.
Improving Environmental Simulation Models To Assess Climate Change Impacts, George P. Malanson, Marc P. Armstrong
Improving Environmental Simulation Models To Assess Climate Change Impacts, George P. Malanson, Marc P. Armstrong
George P Malanson
Increased levels of atmospheric carbon dioxide and other by-products of human civilization are expected to disrupt the global energy budget and induce climatic change, which will aIter the distribution of plant species and the composition of plant communities. In spite of the importance of these projected effects, our understanding of the processes leading to such changes needs to be strengthened. This paper addresses the need to improve models that are used to assess spatial aspects of the response of vegetation to anthropogenic climate change. Several modifications are suggested, each of which relates to changes in forest community composition that occur …
Complexity Theory, Spatial Simulation Models, And Land Use Dynamics In The Northern Ecuadorian Amazon, Stephen Walsh, Joseph Messina, Carlos Mena, George Malanson
Complexity Theory, Spatial Simulation Models, And Land Use Dynamics In The Northern Ecuadorian Amazon, Stephen Walsh, Joseph Messina, Carlos Mena, George Malanson
George P Malanson
No abstract provided.
Directional Positive Feedback And Pattern At An Alpine Tree Line, Kathryn Alftine, George Malanson
Directional Positive Feedback And Pattern At An Alpine Tree Line, Kathryn Alftine, George Malanson
George P Malanson
No abstract provided.
Endogenous Fractal Dynamics At Alpine Treeline Ecotones, Yu Zeng, George Malanson
Endogenous Fractal Dynamics At Alpine Treeline Ecotones, Yu Zeng, George Malanson
George P Malanson
Many of the hypotheses proposed to explain ecotones are based on an individualistic paradigm and are essentially static. While they include local feedbacks, they ignore the interactions between pattern and process across scales. These feedbacks in ecotones are nonlinear in nature and complicate the relations of pattern and process in vegetation, which, combined with observed fractal patterns, suggests a complexity science approach to investigate ecotone dynamics. A cellular automaton of alpine treeline, including nonlinear, local, positive, and negative feedbacks in tree establishment and mortality, as reported in field studies, is used as a model system. Fourier analysis of simulated alpine …
Potential Catastrophic Flooding From Landslide-Dammed Lakes, Glacier National Park, Montana, Usa, David Butler, George Malanson, Jack Oelfke
Potential Catastrophic Flooding From Landslide-Dammed Lakes, Glacier National Park, Montana, Usa, David Butler, George Malanson, Jack Oelfke
George P Malanson
The Rocky Mountains have a high hazard potential from rapid slope failures, subsequent damming of drainage systems, and catastrophic rapid drainage of the landslide-dammed lake. Most landslide dams eventually fail by overtopping. This paper examines the history of, and the potential for catastrophic failure and high discharges from, a pair of landslide-dammed lakes in Glacier National Park, Montana, USA. Tree-ring and lichen data from the surface and margins of the rockfall-avalanche dams indicate contemporaneous deposition occurred in 1910, with additional deposition in 1946. The rockfall-avalanche dams overlie Cretaceous shale capped with late Pleistocene glacial till. The deposits are therefore inherently …