78 research outputs found

    Ecological interactions of the cadmium- and zinc-hyperaccumulating plant, Thlaspi caerulescens, and their implications for phytoremediation

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    The success of invasive species can be attributed to a combination of abiotic factors, such as abundant resources and favorable climate, and biotic factors, such as low levels of competition and predation or herbivory, at the introduced location. While studies have demonstrated the effects of these factors on known invasive species, the degree to which these factors affect a non-native species can be used to predict its likelihood of becoming invasive. The metal-hyperaccumulating plant Thlaspi caerulescens (Brassicaceae) is potentially useful for remediating soils that are moderately contaminated with Cd and Zn, and has been experimentally introduced to contaminated sites outside of its native range for phytoremediation. To assess the ecological risks involved in introducing metal-hyperaccumulating plants for phytoremediation, including their potential invasiveness, I have performed three studies to examine the abiotic and biotic factors that could influence the establishment of T. caerulescens at three contaminated sites near the Rocky Mountain Biological Laboratory in Gothic, Colorado. In the first two studies, I test the effects of soil metal concentrations and interspecific competition on plant performance, and in the third study I examine the strength of herbivore pressure on this plant. Results from these studies show that the growth rate of T. caerulescens in field conditions is generally low, but higher where there are high concentrations of soil Zn and low concentrations of soil Cu. Interspecific competition between T. caerulescens and a native congener is weak overall, and herbivory pressure from a native Lepidopteran herbivore is also low. Therefore, abiotic conditions are more limiting to T. caerulescens than biotic interactions, and would likely prevent T. caerulescens from becoming invasive or spreading outside of contaminated soils at these sites. In the fourth chapter, I use a long-term dataset to describe the demography of Frasera speciosa (Gentianaceae), a long-lived monocarpic plant. Results show that the population is stable, and despite the low elasticity values for the reproductive stages, masting events must be observed to describe accurately the population dynamics of this species

    THE ATTACK DYNAMICS AND ECOSYSTEM CONSEQUENCES OF STEM BORER HERBIVORY ON SITKA WILLOW AT MOUNT ST. HELENS

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    Variation in plant quality across space and time is considered a driving force behind the heterogeneous distribution of herbivorous insects on their host plants. At the same time, herbivory itself can mediate ecosystem processes that can cause feedbacks directly affecting plant quality. Here I examine both of these processes in a primary successional system to ask how insect herbivory can shape successional outcomes. I performed a three year observational study to determine which host plant factors - stress, vigor, and sex - were associated with insect herbivory by the poplar willow weevil (Cryptorynchus lapathi) on Sitka willow (Salix sitchensis), a dioecious pioneer shrub recolonizing Mount St. Helens after the 1980 eruption. I found that weevils prefer or perform best on vigorously growing willows that are seasonally water stressed. This result highlights the need to integrate hypotheses regarding insect response to stress and vigor into a single phenologically based framework focusing on nutrient mobilization to early insect herbivore life stages. I performed a field experiment involving leaf litter from stems attacked and not by weevils to determine whether weevils mediate nutrient cycling by altering willow leaf litter quality or resources available in its root environment. I found that although weevils do not consume leaves directly, stem herbivory is associated with a large reduction in leaf phosphorus, which in turn decelerates phosphorus cycling on Mount St. Helens. Lastly, I performed observational and experimental studies to show that the large female bias seen in willow on Mount St. Helens is not caused by weevil herbivory or other late acting ecological factors, but likely result from biased seed sex ratios. Taken together, these results suggest that weevil herbivory is retarding willow colonization in upland areas on Mount St. Helens, possibly allowing for alternative successional trajectories

    The Blind Spot in the Green Revolution: Temples, Terraces, and Rice Farmers of Bali

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    This is a teaching case study based on the anthropological research of Dr. Steven Lansing, and part of the SESYNC collection of socio-environmental case studies (www.sesync.org)This case explores the complex interactions in a socio-environmental system, the Balinese wet rice cultivation system. Using a combination of the interrupted case and directed case methods, students are presented with an issue that arose during the implementation of Green Revolution agricultural policies in Bali: rice farmers were required to plant new high yield rice varieties continuously rather than following the coordinated cropping schedules set up by water temple priests. Students examine qualitative and quantitative data from classic anthropological research by Dr. Steven Lansing to learn about the important role that water temples play in achieving sustainable rice cultivation in Bali. Using a model that synthesizes ecological, hydrological, and ethnographic data, Lansing and his colleague, Dr. James Kremer, were able to demonstrate that temple priests determine the cropping schedules for farmers in a way that reduces pest growth and helps to manage limited water resources, maximizing rice yields. This four-part case can be used for a wide range of courses in a few class periods (total class time approximately 4.5-5 hrs.)This work was supported by the University of Maryland and NSF Award # DBI-1052875 to the National Socio-Environmental Synthesis Center (SESYNC

    Save the Turtles! And the Grizzlies? Or the Woodpeckers? Prioritizing Endangered Species Conservation

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    This is a teaching resource developed to teach about socio-environmental synthesis. Specifically, it is a case study teaching activity focused on endangered species conservation.This case study explores the complexities involved in endangered species management and provides an opportunity for students to perform an exercise in socio-environmental synthesis. Developed for introductory undergraduate courses in environmental studies or conservation biology, it contains suggested modifications for upper-level undergraduate and graduate courses. Students take the position of wildlife managers who must decide how best to allocate limited resources for conserving multiple threatened and endangered species. Students are provided with data on the ecological characteristics and socio-economic circumstances for a set of five species, and then work in small groups to develop conservation priority rankings based on those data. Students summarize their decisions in writing and in small-group presentations, and the case concludes with an instructor-led discussion of how actual conservation priorities are determined.NSF Award # DBI-1052875 to the National Socio-Environmental Synthesis Cente

    Pan-Antarctic analysis aggregating spatial estimates of Adélie penguin abundance reveals robust dynamics despite stochastic noise

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    © The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Nature Communications 8 (2017): 832, doi:10.1038/s41467-017-00890-0.Colonially-breeding seabirds have long served as indicator species for the health of the oceans on which they depend. Abundance and breeding data are repeatedly collected at fixed study sites in the hopes that changes in abundance and productivity may be useful for adaptive management of marine resources, but their suitability for this purpose is often unknown. To address this, we fit a Bayesian population dynamics model that includes process and observation error to all known AdĂ©lie penguin abundance data (1982–2015) in the Antarctic, covering >95% of their population globally. We find that process error exceeds observation error in this system, and that continent-wide “year effects” strongly influence population growth rates. Our findings have important implications for the use of AdĂ©lie penguins in Southern Ocean feedback management, and suggest that aggregating abundance across space provides the fastest reliable signal of true population change for species whose dynamics are driven by stochastic processes.H.J.L., C.C.-C., G.H., C.Y., and K.T.S. gratefully acknowledge funding provided by US National Aeronautics and Space Administration Award No. NNX14AC32G and U.S. National Science Foundation Office of Polar Programs Award No. NSF/OPP-1255058. S.J., L.L., M.M.H., Y.L., and R.J. gratefully acknowledge funding provided by US National Aeronautics and Space Administration Award No. NNX14AH74G. H.J.L., C.Y., S.J., Y.L., and R.J. gratefully acknowledge funding provided by U.S. National Science Foundation Office of Polar Programs Award No. NSF/PLR-1341548. S.J. gratefully acknowledges support from the Dalio Explore Fund

    Assessing the umbrella value of a range-wide conservation network for Jaguars (Panthera onca)

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    Umbrella species are employed as conservation short-cuts for the design of reserves or reserve networks. However, empirical data on the effectiveness of umbrellas is equivocal, which has prevented more widespread application of this conservation strategy. We perform a novel, large-scale evaluation of umbrella species by assessing the potential umbrella value of a jaguar (Panthera onca) conservation network (consisting of viable populations and corridors) that extends from Mexico to Argentina. Using species richness, habitat quality, and fragmentation indices of similar to 1500 co-occurring mammal species, we show that jaguar populations and corridors overlap a substantial amount and percentage of high-quality habitat for co-occurring mammals and that the jaguar network performs better than random networks in protecting high-quality, interior habitat. Significantly, the effectiveness of the jaguar network as an umbrella would not have been noticeable had we focused on species richness as our sole metric of umbrella utility. Substantial inter-order variability existed, indicating the need for complementary conservation strategies for certain groups of mammals. We offer several reasons for the positive result we document, including the large spatial scale of our analysis and our focus on multiple metrics of umbrella effectiveness. Taken together, our results demonstrate that a regional, single-species conservation strategy can serve as an effective umbrella for the larger community and should help conserve viable populations and connectivity for a suite of co-occurring mammals. Current and future range-wide planning exercises for other large predators may therefore have important umbrella benefits

    Species recovery in the united states: Increasing the effectiveness of the endangered species act

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    The Endangered Species Act (ESA) has succeeded in shielding hundreds of species from extinction and improving species recovery over time. However, recovery for most species officially protected by the ESA - i.e., listed species-has been harder to achieve than initially envisioned. Threats to species are persistent and pervasive, funding has been insufficient, the distribution of money among listed species is highly uneven, and at least 10 times more species than are actually listed probably qualify for listing. Moreover, many listed species will require ongoing management for the foreseeable future to protect them from persistent threats. Climate change will exacerbate this problem and increase both species risk and management uncertainty, requiring more intensive and controversial management strategies to prevent species from going extinct

    Global analysis reveals complex demographic responses of mammals to climate change

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    Approximately 25 % of mammals are threatened globally with extinction, a risk that is amplified under climate change1. Persistence under climate change is determined by the combined effects of climatic factors on multiple demographic rates (survival, development, reproduction), and hence, on population dynamics2. Thus, to quantify which species and places on Earth are most vulnerable to climate-driven extinction, a global understanding of how demographic rates respond to climate is needed3. We synthesise information on such responses in terrestrial mammals, where extensive demographic data are available4. Given the importance of assessing the full spectrum of responses, we focus on studies that quantitatively link climate to multiple demographic rates. We identify 106 such studies, corresponding to 86 mammal species. We reveal a strong mismatch between the locations of demographic studies and the regions and taxa currently recognised as most vulnerable to climate change5,6. Moreover, we show that the effects of climate change on mammals will operate via complex demographic mechanisms: a vast majority of mammal populations display projected increases in some demographic rates but declines in others. Assessments of population viability under climate change therefore need to account for multiple demographic responses. We advocate to prioritise coordinated actions to assess mammal demography holistically for effective conservation worldwide

    The call of the emperor penguin: Legal responses to species threatened by climate change

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    Species extinction risk is accelerating due to anthropogenic climate change, making it urgent to protect vulnerable species through legal frameworks in order to facilitate conservation actions that help mitigate risk. Here, we discuss fundamental concepts for assessing climate change risks to species using the example of the emperor penguin (Aptenodytes forsteri), currently being considered for protection under the US Endangered Species Act (ESA). This species forms colonies on Antarctic sea ice, which is projected to significantly decline due to ongoing greenhouse gas (GHG) emissions. We project the dynamics of all known emperor penguin colonies under different GHG emission scenarios using a climate-dependent meta-population model including the effects of extreme climate events based on the observational satellite record of colonies. Assessments for listing species under the ESA require information about how species resiliency, redundancy and representation (3Rs) will be affected by threats within the foreseeable future. Our results show that if sea ice declines at the rate projected by climate models under current energy system trends and policies, the 3Rs would be dramatically reduced and almost all colonies would become quasi-extinct by 2100. We conclude that the species should be listed as threatened under the ESA

    COMADRE: A global data base of animal demography

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    This is the final version. Available on open access from Wiley via the DOI in this recordData accessibility: The data associated with this manuscript can be accessed at www.comadre-db.orgThe open-data scientific philosophy is being widely adopted and proving to promote considerable progress in ecology and evolution. Open-data global data bases now exist on animal migration, species distribution, conservation status, etc. However, a gap exists for data on population dynamics spanning the rich diversity of the animal kingdom world-wide. This information is fundamental to our understanding of the conditions that have shaped variation in animal life histories and their relationships with the environment, as well as the determinants of invasion and extinction. Matrix population models (MPMs) are among the most widely used demographic tools by animal ecologists. MPMs project population dynamics based on the reproduction, survival and development of individuals in a population over their life cycle. The outputs from MPMs have direct biological interpretations, facilitating comparisons among animal species as different as Caenorhabditis elegans, Loxodonta africana and Homo sapiens. Thousands of animal demographic records exist in the form of MPMs, but they are dispersed throughout the literature, rendering comparative analyses difficult. Here, we introduce the COMADRE Animal Matrix Database, an open-data online repository, which in its version 1.0.0 contains data on 345 species world-wide, from 402 studies with a total of 1625 population projection matrices. COMADRE also contains ancillary information (e.g. ecoregion, taxonomy, biogeography, etc.) that facilitates interpretation of the numerous demographic metrics that can be derived from its MPMs. We provide R code to some of these examples. Synthesis: We introduce the COMADRE Animal Matrix Database, a resource for animal demography. Its open-data nature, together with its ancillary information, will facilitate comparative analysis, as will the growing availability of databases focusing on other aspects of the rich animal diversity, and tools to query and combine them. Through future frequent updates of COMADRE, and its integration with other online resources, we encourage animal ecologists to tackle global ecological and evolutionary questions with unprecedented sample size.Australian Research Council (ARC)Evolutionary Demography Laboratory at the Max Planck Institute for Demographic Research (MPIDR)Natural Environment Research Council (NERC
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