@article {JRN54655, title = {A new landscape classification system for monitoring and assessment of pastures}, journal = {Journal of Soil and Water Conservation}, volume = {69:17A-21A}, year = {2014}, abstract = {

Pasturelands in the United States span a broad range of climate, soils, physical sites, and management. Rather than treat each site as a unique entity, this diversity must be classified into basic units for research and management purposes. A similar system based on ecological principles is needed for temperate semiarid to subhumid to humid areas. Forage suitability groups (FSG; a system based on soil types) offer one approach for doing so, but are heavily based on expert opinion and management regime. A quantitative scientifically-based system like the ecological site description scheme (ESD) used in rangelands would provide a uniform approach to assessing all grazing lands, allow the identification of reference states for monitoring and assessment, and facilitate the creation of state and transition models suitable for pasture systems. We propose a new system based on a probabilistic hierarchical classification of ecologically-relevant climatic, topographic and edaphic variables, which will provide continuity in assessing ecological services across a broad spectrum of grazing lands.

}, doi = {10.2489/jswc.691.17A}, author = {Sarah Goslee and Matt A Sanderson and K. Spaeth and Jeffrey E. Herrick and Ogles, Kevin} } @article {50445, title = {Spatial prediction of invasion success across heterogeneous landscapes using an individual-based model}, journal = {Biological Invasions}, volume = {8}, year = {2006}, note = {This record is duplicated by $\#$161851 which should not be used for reporting or appraisal purposes.}, month = {March 2006}, pages = {193-200}, abstract = {

We used an individual-based simulation model (ECOTONE) in conjunction with climate and soil texture data in a GIS to identify grassland sites in Colorado where the invasive perennial forb, Acroptilon repens (Russian knapweed), is likely to be successful. We also created a threat map indicating the most vulnerable regions for future invasion within the state. This species is a serious problem throughout western rangelands of the U.S. and Canada. Our results show that A. repens has the potential to become most abundant in dry areas with fine-textured soils. Validation of model results with existing infested sites shows that additional areas are at risk from invasion. This information can be used to direct management efforts towards the areas at greatest risk, allowing the most effective use of limited resources.

}, keywords = {acroptilon repens, climate, Colorado, geographic information systems, grassland, grassland sites, individual-based simulation model, invasion, Russian knapweed, soil texture, spatial prediction}, doi = {10.1007/s10530-004-2954-y}, url = {/files/bibliography/06-020.pdf}, author = {Sarah Goslee and Debra C. Peters and Beck, K.G.} } @article {50771, title = {Distribution of Russian knapweed in Colorado: Climate and environmental factors}, journal = {Journal of Range Management}, volume = {56}, number = {6}, year = {2003}, note = {ProCite field[29]: July 29, 2002ProCite field[36]: 2007ProCite field[39]: 03-007}, month = {May 1, 2003}, pages = {206-212}, abstract = {Russian knapweed (Acroptilon repens (L.) DC.) was introduced to the western United States during the early 1900s. This invasive perennial was a contaminant of alfalfa seed and was distributed widely across Colorado. Thus, current distributions reflect the climate and soils tolerances of Russian knapweed and management history rather than dispersal processes. We surveyed extension and weed agents across Colorado and were able to locate 528 current or recently eliminated Russian knapweed stands. These patches were superimposed on climate and soils maps to identify 1-km grid cells that were known to contain Russian knapweed. The status of Russian knapweed within a cell was used as the dependent variable in a logistic regression model to define the environmental envelope for this species. At the scale of our analysis, Russian knapweed was most prevalent on fine-textured soils (clay and clay loam) and in warmer, drier regions of Colorado (precipitation 18-73 cm/yr, mean annual temperature 1-12 C). June precipitation was the most important single factor, although nearly all environmental, annual and monthly climatic factors were significantly related to Russian knapweed occurrence. The multivariate logistic regression model we developed was used to predict the probability of Russian knapweed occurrence for the entire state of Colorado. Our predictions matched the areas of highest abundance of Russian knapweed from a new field survey and also indicated areas of high risk that were not identified by the field survey.}, url = {http://jrm.library.arizona.edu/jrm/GetFileServlet?file=file:///data1/pdf/TheJournalOfRangeManagement/Volume56/Number3/azu_jrm_v56_n3_206_212_m.pdf\&type=application/pdf}, author = {Sarah Goslee and Beck, K.G. and Debra C. Peters} } @article {50772, title = {High-resolution images reveal rate and pattern of shrub encroachment over six decades in New Mexico, USA}, journal = {Journal of Arid Environments}, volume = {54}, number = {4}, year = {2003}, month = {August 1, 2003}, pages = {755-767}, abstract = {

Encroachment of the shrub Prosopis glandulosa (honey mesquite) into semiarid grasslands is a serious concern in the southwestern United States, yet little is known about the long-term dynamics of the invasion process. We used 10 high-resolution aerial and satellite images taken from 1936 to 1996 to track population dynamics and spatial pattern of all P. glandulosa greater than 2m in diameter on a 75-ha area in southern New Mexico. Shrub cover and patch numbers increased from 1936 to the 1970s, then stabilized at 43\% cover and 83 patches/ha. Individual patches were extremely persistent: 95\% of the area occupied by shrub patches in 1936 was still occupied in 1996. Recruitment into the 2m size class was more variable: 0.6 to 5.2\%/yr (mean 0.8\% yr). Patch shape complexity increased from 1936 to 1983 as adjacent shrubs merged and then declined as those clusters filled in and became rounder. Spatial pattern of shrubs showed a distinct trend over time: strongly clustered in 1936 at lag distances up to 250m, then random arrangement at all scales; and, by 1983 the pattern was regular at lag distances greater than 100m. There was no clear relationship with precipitation. The use of remote sensing imagery allowed us to examine one site over time and revealed patterns in population dynamics and spatial pattern that would not have been visible otherwise. Comparison of field estimates collected in 2001 with 1996 image data suggest the canopy cover estimates were accurate, but shrub densities were seriously underestimated in the satellite photographs which do not show shrubs smaller than 2m diameter. As long as limitations of the imagery are understood, these methods can be applied over a larger and more heterogeneous area to examine environmental correlates of invasion success.

}, url = {/files/bibliography/03-017.pdf}, author = {Sarah Goslee and Kris Havstad and Debra C. Peters and A. Rango and W. H. Schlesinger} } @conference {50871, title = {The landscape as probability layers, or why is this plant here and not there?}, booktitle = {17th Annual Symposium, US-International Association for Landscape Ecology}, year = {2002}, month = {April 23-26, 200}, pages = {64}, address = {Lincoln, NE}, abstract = {Plant spatial pattern is determined by complex interactions between a number of factors. Seed dispersal and plant interactions (competition and facilitation) are explicitly spatial. Species-specific environmental heterogeneity adds additional complexity. The landscape can be visualized as a series of superimposed layers describing the probability of establishment, growth and mortality for a particular species at any point in the landscape based on the interaction between environmental heterogeneity and the locations of already established plants. An individual-based model realizing this concept was developed with the objective of untangling the contribution of different spatial plant processes to particular configurations of individuals on the landscape. The model was designed to be extremely flexible so that a wide variety of seed dispersal patterns, plant interactions, and environmental responses could be included. A secondary goal was to create realistic artificial landscapes based on known processes that can be used to test ecological analysis methods. This probability-based spatial approach can be applied to a variety of ecosystems and theoretical questions and has produced novel insights into the effect of various processes on plant spatial pattern.}, author = {Sarah Goslee} } @article {50995, title = {Modeling invasive weeds in grasslands: The role of allelopathy in Acroptilon repens invasion}, journal = {Ecological Modelling}, volume = {139}, number = {1}, year = {2001}, month = {February 1, 2001}, pages = {31-45}, abstract = {We used an individual plant-based simulation model (ECOTONE) to evaluate the importance of allelopathy and soil texture to the invasion of semiarid grasslands by Acroptilon repens. We also assessed the sensitivity of model results to the negative effects of allelochemicals on recruitment and growth of perennial grasses. The ECOTONE model was parameterized for a shortgrass community in eastern Colorado. Experimental simulations used plots with four soil textures and a range of levels of plant sensitivity to allelochemicals. Simulation results showed that A. repens did not dominate the aboveground biomass unless native species were negatively affected by allelochemicals. At moderate levels of plant sensitivity, A. repens became dominant faster and reached a larger proportion of total biomass on fine- compared to coarse-textured soils. Community composition and rate of A. repens dominance were more affected by the sensitivity of plant growth to allelochemicals than sensitivity of recruitment. Allelopathic interactions were an important component of the invasion dynamics of this perennial invasive weed, and further field investigation is warranted.}, url = {/files/bibliography/01-026.pdf}, author = {Sarah Goslee and Debra C. Peters and Beck, K.G.} } @conference {51073, title = {Reconnaissance satellite photos show the recent history of shrub recruitment and survival in desert grasslands}, booktitle = {85th Annual Meeting, Ecological Society of America}, year = {2000}, month = {August 6-10, 200}, pages = {280}, address = {Snowbird, UT}, abstract = {Certain shrub species, particularly Prosopis glandulosa and Larrea tridentata, have increased dramatically in the southwestern US during the past few decades, replacing the original grassland vegetation. We obtained a temporal series of high-resolution military satellite images beginning in the early 1960s, with the goal of monitoring shrub invasion over a large area to determine the topographic and climatic controls on shrub seedling establishment and the rate of expansion of shrub cover. Although the total area of shrub cover increased over time, both the number of shrubs and their size distributions were highly variable. Mortality in small shrubs was high, but once shrubs reached a threshold size, they were likely to persist for long periods. Shrub establishment and survival were related to both climatic factors and topographic features, particularly precipitation and drainage. Our results provide valuable information for those interested din the management and restoration of the desert grasslands of the southwestern US.}, keywords = {desert grasslands, history, Larrea tridentata, prosopis glandulosa, reconnaissance, satellite, shrub recruitment}, author = {Sarah Goslee and Debra C. Peters and Kris Havstad and W. H. Schlesinger} } @conference {51148, title = {Invasion of grasslands by exotic perennial weeds: Allelopathy and soil texture effects}, booktitle = {84th Annual Meeting of the Ecological Society of America}, volume = {80}, year = {1999}, month = {1999}, pages = {94}, address = {Spokane, WA}, abstract = {Invasion of native ecosystems by exotic perennial weeds is an increasingly important ecological problem, yet the key processes involved remain poorly understand for many species. Our objective was to evaluate the importance of allelopathy to the invasion by Acroptilon repens (Russian knapweed) into native semiarid grasslands. Based upon the inverse texture hypothesis, we expected the strength of the allelopathic affect to be related to soil texture and its effects on soil water availability. We used an individual plant-based simulation model (ECOTONE) to evaluate the importance of allelopathy to invasion by Russian knapweed into shortgrass communities in eastern Colorado over a range of soil textures. We found that allelopathy was more important for fine-textured soils where allelochemicals became concentrated in the rooting zone of grasses compared to soils with high sand contents where leaching of allelochemicals occurred. Rates of invasion nwere faster and more complete dominance by Russian knapweed occurred on fine- compared to coarse-textured soils. Our results have important implications for the management and sustainability of these grasslands under the threat of invasion by perennial weeds.}, keywords = {Allelopathy, grasslands, invasion, perennial weeds, soil texture}, author = {Sarah Goslee and Debra C. Peters and Beck, K.G.} } @conference {51149, title = {Modeling the long-term dynamics of an invasive perennial weed in Colorado, USA}, booktitle = {5th World Congress, US-International Association for Landscape Ecology}, volume = {I (A-K)}, year = {1999}, month = {July 29-August 3}, pages = {55}, address = {Snowmass Village, CO}, abstract = {Invasion of native ecosystems by exotic perennial weeds is an increasingly important ecological problem. In most cases, little is known about the potential long-term impact of a species which has been introduced to a new area. Without this knowledge it is difficult to predict the eventual impact of that species on native ecosystems. Our objective was to evaluate the dynamics of the weed Acroptilon repens (Russian knapweed) within the State of Colorado. We used an individual plant-based simulation model (ECOTONE) to examine the long-term dynamics of Russian knapweed in sites across the range of soil textures and climates found in Colorado. Simulation results suggested that Russian knapweed will be most successful over the long term in areas with particular combinations of soil texture and climate. We used the model results to identify the regions of Colorado in which Russian knapweed establishment is likely to lead to continued dominance, as well as sthose regions where knapweed will probably be outcompeted by native grasses. These results can be used to target management programs to the areas where they are most crucial. This approach can also be used to develop appropriate management programs for other perennial weeds.}, keywords = {Colorado, modeling, modelling, perennial weeds, Russian knapweed}, author = {Sarah Goslee and Debra C. Peters and Beck, K.G.} }