National Socio Environmental Synthesis Center
National Socio Environmental Synthesis Center
Marchand P.,National Socio Environmental Synthesis Center |
Boenke M.,McGill University |
Green D.M.,McGill University
Ecological Modelling | Year: 2017
Although amphibians typically exhibit high site fidelity and low dispersal, they do undertake rare, long-distance movements. The factors influencing these events remain poorly understood, partly because amphibian spring movements tend to radiate from breeding sites and the animals are often difficult to locate at other times of the year. In this study, we investigate whether these movement patterns can be reproduced by a parsimonious model where foraging steps follow a heavy-tailed, Lévy alpha-stable distribution and individuals may either return to a previous refuge site or establish a new one. We consider three versions of the return behaviour: (1) a distance-independent probability of return to any previous refuge; (2) constant probability of return to the nearest refuge; or (3) a distance-dependent probability of return to each refuge. Using approximate Bayesian computation, we fit each version of the model to radiotracking data from a population of Fowler's Toads, which inhabits a linear sand dune habitat on the north shore of Lake Erie in Ontario, Canada. Only the model with distance-independent, random returns provides a good fit of the inter-refuge distance distribution and the number of refuges visited per toad. Our results suggest that while toads occasionally forage over long distances, the establishment of new refuges is not driven by the minimization of energy expenditure. © 2017 Elsevier B.V.
Zambrano J.,National Socio Environmental Synthesis Center |
Marchand P.,National Socio Environmental Synthesis Center |
Swenson N.G.,University of Maryland University College
Proceedings of the Royal Society B: Biological Sciences | Year: 2017
Tree neighbourhood modelling has significantly contributed to our understanding of the mechanisms structuring communities. Investigations into the impact of neighbouring crowding on tree performance have generally been conducted at local scales, missing important regional-scale context such as the suitability of the climate for each species. Favourable climates may enhance tree performance, but this may come at the cost of increased neighbourhood crowding and competition negatively impacting survival and growth. Through the synthesis of continental-scale forest inventory and trait datasets from the northeast USA and Puerto Rico we present an analytical approach that elucidates the important interactions between local competitive and regional climatic contexts. Our results show strong asymmetries in competitive interactions and significant niche differences that are dependent on habitat suitability. The strong interaction between local neighbourhood and regional climate highlights the need for models that consider the interaction between these two processes that have been previously ignored. © 2017 The Author(s) Published by the Royal Society. All rights reserved.
Magliocca N.R.,University of Maryland Baltimore County |
Magliocca N.R.,National Socio Environmental Synthesis Center |
Brown D.G.,University of Michigan |
Ellis E.C.,University of Maryland Baltimore County
PLoS ONE | Year: 2014
Local changes in land use result from the decisions and actions of land-users within land systems, which are structured by local and global environmental, economic, political, and cultural contexts. Such cross-scale causation presents a major challenge for developing a general understanding of how local decision-making shapes land-use changes at the global scale. This paper implements a generalized agent-based model (ABM) as a virtual laboratory to explore how global and local processes influence the land-use and livelihood decisions of local land-users, operationalized as settlement-level agents, across the landscapes of six real-world test sites. Test sites were chosen in USA, Laos, and China to capture globally-significant variation in population density, market influence, and environmental conditions, with land systems ranging from swidden to commercial agriculture. Publicly available global data were integrated into the ABM to model cross-scale effects of economic globalization on local land-use decisions. A suite of statistics was developed to assess the accuracy of model-predicted land-use outcomes relative to observed and random (i.e. null model) landscapes. At four of six sites, where environmental and demographic forces were important constraints on land-use choices, modeled land-use outcomes were more similar to those observed across sites than the null model. At the two sites in which market forces significantly influenced land-use and livelihood decisions, the model was a poorer predictor of land-use outcomes than the null model. Model successes and failures in simulating real-world land-use patterns enabled the testing of hypotheses on land-use decision-making and yielded insights on the importance of missing mechanisms. The virtual laboratory approach provides a practical framework for systematic improvement of both theory and predictive skill in land change science based on a continual process of experimentation and model enhancement. © 2014 Magliocca et al.
Motesharrei S.,University of Maryland College Park |
Motesharrei S.,National Socio Environmental Synthesis Center |
Rivas J.,University of Minnesota |
Rivas J.,Institute of Global Environment and Society IGES |
Kalnay E.,University of Maryland College Park
Ecological Economics | Year: 2014
There are widespread concerns that current trends in resource-use are unsustainable, but possibilities of overshoot/collapse remain controversial. Collapses have occurred frequently in history, often followed by centuries of economic, intellectual, and population decline. Many different natural and social phenomena have been invoked to explain specific collapses, but a general explanation remains elusive.In this paper, we build a human population dynamics model by adding accumulated wealth and economic inequality to a predator-prey model of humans and nature. The model structure, and simulated scenarios that offer significant implications, are explained. Four equations describe the evolution of Elites, Commoners, Nature, and Wealth. The model shows Economic Stratification or Ecological Strain can independently lead to collapse, in agreement with the historical record.The measure "Carrying Capacity" is developed and its estimation is shown to be a practical means for early detection of a collapse. Mechanisms leading to two types of collapses are discussed. The new dynamics of this model can also reproduce the irreversible collapses found in history. Collapse can be avoided, and population can reach a steady state at maximum carrying capacity if the rate of depletion of nature is reduced to a sustainable level and if resources are distributed equitably. © 2014.
Acuna V.,Catalan Institute for Water Research |
Datry T.,IRSTEA |
Marshall J.,Information Technology |
Marshall J.,Griffith University |
And 11 more authors.
Science | Year: 2014
Intermittently flowing streams and rivers should be recognized, afforded protection, and better managed.
Randell H.,National Socio Environmental Synthesis Center |
Gray C.,University of North Carolina at Chapel Hill
Global Environmental Change | Year: 2016
This paper examines the effects of climate variability on schooling outcomes in rural Ethiopia. Investments in education serve as an important pathway out of poverty, yet reduced agricultural productivity due to droughts or temperature shocks may affect educational attainment if children receive poorer nutrition during early childhood, are required to participate in household income generation during schooling ages, or if households can no longer pay for school-related expenses. We link longitudinal socioeconomic, demographic, and schooling data from the Ethiopian Rural Household Survey to high-resolution gridded climate data to measure exposure to temperature and precipitation relative to historical norms. We then estimate a set of multivariate regression models to understand how climate variability impacts grade attainment and school enrollment. Results indicate that early life climatic conditions – namely milder temperatures during all seasons and greater rainfall during the summer agricultural season – are associated with an increased likelihood of a child having completed any education. In addition, greater summer rainfall during both early life and school ages is associated with having completed any schooling as well as with attending school at the time of the survey. These findings suggest that future climate change may reduce children's school participation in rural Sub-Saharan Africa, slowing progress toward human development goals and poverty alleviation. © 2016 Elsevier Ltd
Zeigler S.L.,University of Maryland University College |
Che-Castaldo J.P.,National Socio Environmental Synthesis Center |
Che-Castaldo J.P.,University of Maryland University College |
Neel M.C.,University of Maryland University College
Conservation Biology | Year: 2013
Use of population viability analyses (PVAs) in endangered species recovery planning has been met with both support and criticism. Previous reviews promote use of PVA for setting scientifically based, measurable, and objective recovery criteria and recommend improvements to increase the framework's utility. However, others have questioned the value of PVA models for setting recovery criteria and assert that PVAs are more appropriate for understanding relative trade-offs between alternative management actions. We reviewed 258 final recovery plans for 642 plants listed under the U.S. Endangered Species Act to determine the number of plans that used or recommended PVA in recovery planning. We also reviewed 223 publications that describe plant PVAs to assess how these models were designed and whether those designs reflected previous recommendations for improvement of PVAs. Twenty-four percent of listed species had recovery plans that used or recommended PVA. In publications, the typical model was a matrix population model parameterized with ≤5 years of demographic data that did not consider stochasticity, genetics, density dependence, seed banks, vegetative reproduction, dormancy, threats, or management strategies. Population growth rates for different populations of the same species or for the same population at different points in time were often statistically different or varied by >10%. Therefore, PVAs parameterized with underlying vital rates that vary to this degree may not accurately predict recovery objectives across a species' entire distribution or over longer time scales. We assert that PVA, although an important tool as part of an adaptive-management program, can help to determine quantitative recovery criteria only if more long-term data sets that capture spatiotemporal variability in vital rates become available. Lacking this, there is a strong need for viable and comprehensive methods for determining quantitative, science-based recovery criteria for endangered species with minimal data availability. © 2013 Society for Conservation Biology.
Zipkin E.F.,U.S. Geological Survey |
Zipkin E.F.,University of Maryland University College |
Ries L.,University of Maryland University College |
Ries L.,National Socio environmental Synthesis Center |
And 3 more authors.
Global Change Biology | Year: 2012
Understanding the impacts of climate on migratory species is complicated by the fact that these species travel through several climates that may be changing in diverse ways throughout their complete migratory cycle. Most studies are not designed to tease out the direct and indirect effects of climate at various stages along the migration route. We assess the impacts of spring and summer climate conditions on breeding monarch butterflies, a species that completes its annual migration cycle over several generations. No single, broad-scale climate metric can explain summer breeding phenology or the substantial year-to-year fluctuations observed in population abundances. As such, we built a Poisson regression model to help explain annual arrival times and abundances in the Midwestern United States. We incorporated the climate conditions experienced both during a spring migration/breeding phase in Texas as well as during subsequent arrival and breeding during the main recruitment period in Ohio. Using data from a state-wide butterfly monitoring network in Ohio, our results suggest that climate acts in conflicting ways during the spring and summer seasons. High spring precipitation in Texas is associated with the largest annual population growth in Ohio and the earliest arrival to the summer breeding ground, as are intermediate spring temperatures in Texas. On the other hand, the timing of monarch arrivals to the summer breeding grounds is not affected by climate conditions within Ohio. Once in Ohio for summer breeding, precipitation has minimal impacts on overall abundances, whereas warmer summer temperatures are generally associated with the highest expected abundances, yet this effect is mitigated by the average seasonal temperature of each location in that the warmest sites receive no benefit of above average summer temperatures. Our results highlight the complex relationship between climate and performance for a migrating species and suggest that attempts to understand how monarchs will be affected by future climate conditions will be challenging. © 2012.
Palmer M.A.,University of Maryland University College |
Palmer M.A.,National Socio Environmental Synthesis Center |
Palmer M.A.,University of Maryland Center for Environmental Science |
Filoso S.,University of Maryland Center for Environmental Science |
And 2 more authors.
Ecological Engineering | Year: 2014
Ecosystem restoration was originally founded upon recovering ecosystems using wildlands as a reference state. More recently there has been interest in shifting to the restoration of ecosystem services - the benefits that natural systems can provide to humans. This shift is resulting in new restoration goals as well as new methodological approaches. The pace at which restoration goals and methods are changing is particularly fast for running-water ecosystems, which calls for a rigorous assessment of the environmental and economic costs and benefits associated with such changes.In this paper, we explore the environmental costs and benefits of an emerging form of urban stream restoration, in which ecosystems are vastly transformed in order to enhance specific ecosystem functions and support desirable services. These projects are usually implemented in highly incised low-order perennial, intermittent, or ephemeral stream reaches. In either case, the stream channel is transformed into a stormwater management structure designed to reduce peak flows and enhance hydraulic retention of stream flow with the goals of reducing bank erosion and promoting retention of nutrients and suspended sediments. Results to date indicate that this novel ecological design approach does modify the hydrologic responses of streams during some storm events, but there is no consistent pattern of nitrogen retention or removal that would lead to net annual benefits. While additional data are needed, results suggest there is the potential for sediment retention, at least during some flows. Ongoing work which includes monitoring both pre- and post-project implementation will help resolve this uncertainty.If sediment retention does occur, it is likely to decrease over time making the lifespan of these highly engineered projects is finite. Furthermore, environmental impacts associated with these projects can include loss or damage of riparian forests and export of sediment pulses during construction which may offset project benefits depending on their lifespan. Therefore, the use of approaches where entire existing ecosystems are modified to enhance a few specific biophysical processes should be limited to the most degraded systems where less invasive techniques, such as upland reforestation, reduced lawn fertilization, or better stormwater management at the source of runoff generation have first been exhausted. © 2013 Elsevier B.V.
Jasny L.,National Socio Environmental Synthesis Center |
Jasny L.,University of Exeter |
Waggle J.,University of Maryland University College |
Fisher D.R.,University of Maryland University College
Nature Climate Change | Year: 2015
Diverse methods have been applied to understand why science continues to be debated within the climate policy domain. A number of studies have presented the notion of the ' echo chamber' to model and explain information flows across an array of social settings, finding disproportionate connections among ideologically similar political communicators. This paper builds on these findings to provide a more formal operationalization of the components of echo chambers. We then empirically test their utility using survey data collected from the community of political elites engaged in the contentious issue of climate politics in the United States. Our survey period coincides with the most active and contentious period in the history of US climate policy, when legislation regulating carbon dioxide emissions had passed through the House of Representatives and was being considered in the Senate. We use exponential random graph (ERG) modelling to demonstrate that both the homogeneity of information (the echo) and multi-path information transmission (the chamber) play significant roles in policy communication. We demonstrate that the intersection of these components creates echo chambers in the climate policy network. These results lead to some important conclusions about climate politics, as well as the relationship between science communication and policymaking at the elite level more generally. © 2015 Macmillan Publishers Limited.