Papers by Bruce D. Maxwell
Predicting Land Use Change in and Around a Rural Community
The Montana Climate Assessment (MCA) is an effort to synthesize, evaluate, and share credible and... more The Montana Climate Assessment (MCA) is an effort to synthesize, evaluate, and share credible and relevant scientific information about climate change in Montana with the citizens of the State. The motivation for the MCA arose from citizens and organizations in Montana who have expressed interest in receiving timely and pertinent information about climate change, including information about historical variability, past trends, and projections of future impacts as they relate to topics of economic concern. This first assessment reports on climate trends and their consequences for three of Montana's vital sectors: water, forests, and agriculture. We consider the MCA to be a sustained effort. We plan to regularly incorporate new scientific information, cover other topics important to the people of Montana, and address the needs of the state. xLII | ACKNOWLEDGMENTS Bridger Range fall sunset. Photograph courtesy of Scott Bischke. The following individuals and/or groups assisted in the creation of this document by providing strategic guidance, contributing to the literature review process, offering insight on stakeholder needs, or helping out administratively. Many of these people were a part of the writing teams' listening sessions that occurred early in the process-a focused effort to get out into the state and ask Montanans, "What do you know about climate change in the state, what do you need that you don't already have, and how would you like information delivered?"
Weed Research, Jun 19, 2018
(2018). You cannot fight fire with fire: a demographic model suggests alternative approaches to m... more (2018). You cannot fight fire with fire: a demographic model suggests alternative approaches to manage multiple herbicide-resistant Avena fatua. Weed Research 58, 357-368.
BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access t... more BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.
Diversity
Pinus contorta is considered one of the most invasive tree species worldwide, generating signific... more Pinus contorta is considered one of the most invasive tree species worldwide, generating significant impacts on biodiversity and ecosystems. In several Patagonian ecosystems in southern Chile, it has escaped from plantations established mainly in the 1970s, and is now invading both forests and treeless environments. In this study, we evaluated the impact of the invasion of P. contorta on microenvironmental conditions in Araucaria araucana forest and Patagonian steppe ecosystems, and assessed how these changes related to the richness and abundance of native and non-native plant species. In each ecosystem, 24 plots of 100 m2 were established along a gradient of P. contorta biomass, where 18 environmental variables and the composition of native and non-native vegetation were measured at a local scale. Our results indicated that increased pine biomass was associated with differences in microclimatic conditions (soil and air temperature, photosynthetically active radiation (PAR), and soi...
Frontiers in Ecology and Evolution, 2022
Future climate projections of warming, drying, and increased weather variability indicate that co... more Future climate projections of warming, drying, and increased weather variability indicate that conventional agricultural and production practices within the Northern Great Plains (NGP) will become less sustainable, both ecologically and economically. As a result, the livelihoods of people that rely on these lands will be adversely impacted. This is especially true for Native American communities, who were relegated to reservations where the land is often vast but marginal and non-tribal operators have an outsized role in food production. In addition, NGP lands are expected to warm and dry disproportionately relative to the rest of the United States. It is therefore critical to identify models of sustainable land management that can improve ecological function and socio-economic outcomes for NGP communities, all while increasing resilience to a rapidly changing climate. Efforts led by Native American Nations to restore North American Plains bison (Bison bison bison) to tribal lands c...
The purpose of this assessment is to a) present understandable, science-based, Montana-specific i... more The purpose of this assessment is to a) present understandable, science-based, Montana-specific information about the impacts of climate change on the health of Montanans; and b) describe how our healthcare providers, state leaders, communities, and individuals can best prepare for and reduce those impacts in the coming decades. This assessment draws from, and is an extension to, the 2017 Montana Climate Assessment (MCA1) (Whitlock et al. 2017), which provides the first detailed analysis of expected impacts to Montana’s water, forests, and agriculture from climate change. MCA explains historical, current, and prospective climate trends for the state based on the best-available science. The 2017 Montana Climate Assessment did not address the impact of climate change on the health of Montanans. This special report of the MCA fills that important knowledge gap; it represents a collaboration between climate scientists and Montana’s healthcare community and is intended to help Montanans ...
Effect of rimsulfuron dose and infestation density on Sorghum halepense populations in maize
Ecology and Society, 2021
Regional Environmental Change, 2020
Invasive plant species are a significant global problem, with the potential to alter structure an... more Invasive plant species are a significant global problem, with the potential to alter structure and function of ecosystems and cause economic damage to managed landscapes. An effective course of action to reduce the spread of invasive plant species is to identify potential habitat incorporating changing climate scenarios. In this study, we used a suite of species distribution models (SDMs) to project habitat suitability of the eleven most abundant invasive weed species across road networks of Montana, USA, under current (2005) conditions and future (2040) projected climates. We found high agreement between different model predictions for most species. Among the environmental predictors, February minimum temperature, monthly precipitation, solar radiation, and December vapor pressure deficit accounted for the most variation in projecting habitat suitability for most of the invasive weed species. The model projected that habitat suitability along roadsides would expand for seven specie...
Applied Vegetation Science, 2018
QuestionHow does type of disturbance alter plant community composition when an invasive species w... more QuestionHow does type of disturbance alter plant community composition when an invasive species with high intrinsic population growth rate is present? The sagebrush steppe is a cold semi‐arid steppe dominated by the native shrub Artemisia tridentata Nutt., native bunchgrasses, and has been invaded by the non‐native winter annual Bromus tectorum L.LocationSagebrush steppe, Montana, USA.MethodsWe assessed the effect of fire and soil disturbance, due to bulldozing to create a firebreak, on the resilience of plant communities and their resistance to invasion by B. tectorum. Plant species richness and species composition were monitored for 3 years at two sites post‐fire and firebreak construction.ResultsBurned plant communities were resilient and had similar native grass cover and native species richness compared with the unburned sites after 3 years. Soil disturbance from firebreak construction resulted in species composition that was distinct and had lower native grass cover. Type of d...
Simulation of Spring-Seeded Smother Plants for Weed Control in Corn (Zea mays)
Weed Science, 1994
Field experiments were conducted to determine the effect of a short-term spring-seeded smother pl... more Field experiments were conducted to determine the effect of a short-term spring-seeded smother plant on corn development and weed control. Yellow mustard was managed to provide interference durations of 2,4,6, or 8 wk, and maximum height of 10 or 20 cm. Three yellow mustard planting patterns and eight seeding rates were evaluated during 1989 and 1990 at St. Paul and Rosemount, MN. Yellow mustard seeded at 2120 seeds m−2with an interference duration of 4 wk and a maximum height of 10 cm decreased corn yield 17% and reduced weed dry weight 4 wk after yellow mustard emergence an average of 66%. Yellow mustard with a 2-wk interference duration did not reduce weed dry weight. Yellow mustard seeded at 2120 seeds m−2with a 6- or 8-wk life cycle and 10-cm height reduced weed dry weight at the end of the interference period an average of 82% but delayed corn silk emergence an average of 5.3 d and reduced average grain yield 19%. Increasing yellow mustard height from 10 to 20 cm delayed corn ...
Biological Invasions, 2019
To best understand plant invasions and predict unexpected outcomes it is necessary to integrate i... more To best understand plant invasions and predict unexpected outcomes it is necessary to integrate information on disturbance, the local environment, and demography. Disturbance by fire has been shown to promote invasions worldwide, but precise interactions between fire, native and invading species remain unclear. Indeed, trade-offs exist between fire-induced mortality of seed sources and increased establishment, driving invasion outcomes. A positive feedback between lodgepole pine (Pinus contorta) invasions and fire has been identified but only above a certain pine density. Above this threshold, fire resulted in increased pine dominance at the plot level, however below this threshold establishment rates did not change. We used a spatially explicit invasion simulation model modified to include fire to explore the implications of these complex interactions between pine invasions and fire. We asked if fire promoted P. contorta invasion across a Patagonian steppe site and if this depended on the age of the invasion when it burned. Our simulations indicated that, although fire was not necessary to initiate invasion, fire in communities where pine invasions were at least 10 years old resulted in increased spatial extent and maximum invasion density compared to unburned simulations. Fire through younger invasions did not alter the progression of the invasion compared to unburned simulations. Pine invasions should be managed before they reach an advanced stage where positive feedbacks between fire and pine invasion could lead to dramatic increases in invasion rate.
Weed Technology, 1988
Weed population models can serve as a framework to organize weed biology information and to devel... more Weed population models can serve as a framework to organize weed biology information and to develop weed control strategies. Models help to identify information gaps, to set research priorities, to develop hypotheses pertinent to weed population regulation, and to suggest control strategies. A population simulation model of leafy spurge (Euphorbia esulaL. # EPHES) was used to demonstrate the applicability of population models to weed science. Sensitivity analysis of an existing leafy spurge model indicated that transition from basal buds to vegetative shoots, survival of vegetative shoots, and survival of basal buds over winter were important transition parameters influencing population growth of this weed species. Possible mechanisms (intraspecific competition and environmental factors) that influence the transition from basal buds to vegetative shoots were shown. Intraspecific density effects on basal bud transition and production were included to show model refinement and second-...
Weed Technology, 1996
Sustainable rangeland management will require successional strategies to deal with the expanding ... more Sustainable rangeland management will require successional strategies to deal with the expanding weed problem. These strategies must be consistent with the view that plant communities are dynamic and technology is used to enhance the natural processes and mechanisms that direct vegetation change. The goal is to shift the dynamics toward a desired plant community. A unified conceptual model is necessary to direct the development and application of successional weed management systems. We propose using a resource management model as a conceptual basis for successional weed management. This model is based on the primary causes of succession: site availability, differential species availability, and differential species performance. This model provides the mechanistic framework necessary for developing successional weed management systems and it is meant to enhance communication among rangeland weed managers and scientists.
Remote Sensing, 2018
Accurate crop yield assessments using satellite remote sensing-based methods are of interest for ... more Accurate crop yield assessments using satellite remote sensing-based methods are of interest for regional monitoring and the design of policies that promote agricultural resiliency and food security. However, the application of current vegetation productivity algorithms derived from global satellite observations is generally too coarse to capture cropland heterogeneity. The fusion of data from different sensors can provide enhanced information and overcome many of the limitations of individual sensors. In thitables study, we estimate annual crop yields for seven important crop types across Montana in the continental USA from 2008-2015, including alfalfa, barley, maize, peas, durum wheat, spring wheat and winter wheat. We used a satellite data-driven light use efficiency (LUE) model to estimate gross primary productivity (GPP) over croplands at 30-m spatial resolution and eight-day time steps using a fused NDVI dataset constructed by blending Landsat (5 or 7) and Terra MODIS reflectance data. The fused 30-m NDVI record showed good consistency with the original Landsat and MODIS data, but provides better spatiotemporal delineations of cropland vegetation growth. Crop yields were estimated at 30-m resolution as the product of estimated GPP accumulated over the growing season and a crop-specific harvest index (HI GPP). The resulting GPP estimates capture characteristic cropland productivity patterns and seasonal variations, while the estimated annual crop production results correspond favorably with reported county-level crop production data (r = 0.96, relative RMSE = 37.0%, p < 0.05) from the U.S. Department of Agriculture (USDA). The performance of estimated crop yields at a finer (field) scale was generally lower, but still meaningful (r = 0.42, relative RMSE = 50.8%, p < 0.05). Our methods and results are suitable for operational applications of crop yield monitoring at regional scales, suggesting the potential of using global satellite observations to improve agricultural management, policy decisions and regional/global food security.
Sustainability, 2016
Modern weed science is at a crossroads. Born out of advances in chemistry, it has focused on mini... more Modern weed science is at a crossroads. Born out of advances in chemistry, it has focused on minimizing weed competition with genetically uniform crops and heavy reliance on herbicides. Paradoxically, the success obtained with such an approach and the reluctance to conduct integrated and multidisciplinary research has resulted in unintended, but predictable, consequences, including the selection of herbicide resistant biotypes. Advances in eco-evolutionary biology, a relatively recent discipline that seeks to understand how local population dynamics arise from phenotypic variation resulting from natural selection, habitat distribution, and propagule dispersal across the landscape are transforming our understanding of the processes that regulate agroecosystems. Within this framework, complementary tactics to develop alternative weed management programs include the following: (1) weed scientists must recognize that evolution occurs within crop fields at ecologically-relevant time scales and is rooted in the inherent variation that exists in all populations; (2) weed management should recognize that the probability of a resistant mutant is directly related to the population size; (3) farmers need to acknowledge that herbicide resistance transcends any one farm and should coordinate local practices with regional actions; (4) incentives should be developed and implemented to help the adoption of eco-evolutionary management programs; and (5) risk analysis can help incorporate an eco-evolutionary perspective into integrated weed management programs.
Ecosystems, 2016
Bromus tectorum can transform ecosystems causing negative impacts on the ecological and economic ... more Bromus tectorum can transform ecosystems causing negative impacts on the ecological and economic values of sagebrush steppe of the western USA. Although our knowledge of the drivers of the regional distribution of B. tectorum has improved, we have yet to determine the relative importance of climate and local factors causing B. tectorum abundance and impact. To address this, we sampled 555 sites distributed geographically and ecologically throughout the sagebrush steppe. We recorded the canopy cover of B. tectorum, as well as local substrate and vegetation characteristics. Boosted regression tree modeling revealed that climate strongly limits the transformative ability of B. tectorum to a portion of the sagebrush steppe with dry summers (that is, July precipitation <10 mm and the driest annual quarter associated with a mean temperature >15°C) and low native grass canopy cover. This portion includes the Bonneville, Columbia, Lahontan, and lower Snake River basins. These areas are likely to require extreme efforts to reverse B. tectorum transformation. Our predictions, using future climate conditions, suggest that the transformative ability of B. tectorum may not expand geographically and could remain within the same climatically suitable basins. We found B. tectorum in locally disturbed areas within or adjacent to all of our sample sites, but not necessarily within sagebrush steppe vegetation. Conversion of the sagebrush steppe by B. tectorum, therefore, is more likely to occur outside the confines of its current climatically optimal region because of site-specific disturbances, including invasive species control efforts and sagebrush steppe mismanagement, rather than climate change.
Ecology, 2017
Invasive plant species that have the potential to alter fire regimes have significant impacts on ... more Invasive plant species that have the potential to alter fire regimes have significant impacts on native ecosystems. Concern that pine invasions in the Southern Hemisphere will increase fire activity and severity and subsequently promote further pine invasion prompted us to examine the potential for feedbacks between Pinus contorta invasions and fire in Patagonia and New Zealand. We determined how fuel loads and fire effects were altered by P. contorta invasion. We also examined post‐fire plant communities across invasion gradients at a subset of sites to assess how invasion alters the post‐fire vegetation trajectory. We found that fuel loads and soil heating during simulated fire increase with increasing P. contorta invasion age or density at all sites. However, P. contorta density did not always increase post‐fire. In the largest fire, P. contorta density only increased significantly post‐fire where the pre‐fire P. contorta density was above an invasion threshold. Below this thresh...
Diversity and Distributions, 2016
Aim To determine whether one of the most invasive pine species introduced to the Southern Hemisph... more Aim To determine whether one of the most invasive pine species introduced to the Southern Hemisphere, Pinus contorta, has changed plant species richness, composition, diversity, and litter depth where it has invaded into native open forest, shrub steppe and grassland communities and to assess whether changes were similar in its native and introduced ranges.
Uploads
Papers by Bruce D. Maxwell