Non-native and native organisms moving into high elevation and high latitude ecosystems in an era of climate change: new challenges for ecology and conservation
Authors: Albihn A, Alexander J, Burgess T, Daehler C, Englund G, Essl F, Evengård B, Greenwood G, Haider S, Lenoir J, McDougall K, Muths E, Nuñez M, Olofsson J, Pellissier L, Rabitsch W, Rew L, Robertson M, Sanders N, Kueffer C, Milbau A, Pauchard A | Date: 2016 | Outlet: Biological Invasions | Format: .PDF
Cold environments at high elevation and high latitude are often viewed as resistant to biological invasions. However, climate warming, land use change and associated increased connectivity all increase the risk of biological invasions in these environments. Here we present a summary of the key discussions of the workshop ‘Biosecurity in Mountains and Northern Ecosystems: Current Status and Future Challenges’ (Flen, Sweden, 1-3 June 2015). The aims of the workshop were to (i) increase awareness about the growing importance of species expansion – both non-native and native – at high elevation and high latitude with climate change, (ii) review existing knowledge about invasion risks in these areas, and (iii) encourage more research on how species will move and interact in cold environments, and the consequences for animal and human health and wellbeing. The diversity of potential and actual invaders reported at the workshop and the likely interactions between them create major challenges for managers of cold environments. However, since these cold environments have experienced fewer invasions when compared with many warmer, more populated environments, prevention has a real chance of success, especially if it is coupled with prioritisation schemes for targeting invaders likely to have greatest impact. Communication and co-operation between cold environment regions will facilitate rapid response and maximise use of limited research and management resources.
Restored agricultural wetlands in central Iowa: habitat quality and amphibian response
Authors: Reeves RA, Pierce CL, Smalling KL, Klaver RW, Vandever MW, Battaglin WA, Muths E | Date: 2016-02 | Outlet: Wetlands | Format: .PDF
Amphibians are declining throughout the United States and worldwide due, partly, to habitat loss. The Iowa Conservation Reserve Enhancement Program (CREP) strategically restores wetlands to denitrify tile drainage effluent and restore ecosystem services. Understanding how eutrophication , hydroperiod, predation, and disease affect amphibians in restored wetlands is central to maintaining healthy amphibian populations in the region. We examined the quality of amphibian habitat in restored CREP wetlands relative to reference wetlands by comparing species richness, developmental stress, and adult leopard frog (Lithobates pipiens) survival probabilities to a suite of environmental metrics. Although measured habitat variables differed between restored and reference wetlands, differences appeared to have sub-lethal rather than lethal effects on resident populations . There were few differences in amphibian species richness and no difference in estimated survival probabilities between wetland types. Restored wetlands had more nitrate and alkaline pH, longer hydroperiods, and were deeper, whereas reference wetlands had more amphibian chytrid fungus zoospores and resident amphibians exhibited increased developmental stress. Restored and reference wetlands are both important components of the landscape in central Iowa and maintaining a complex of fish-free wetlands with a variety of hydroperiods will likely contribute to the persistence of amphibians in this landscape.
An alternative framework for responding to the amphibian crisis
Authors: Muths E, Fisher RN | Outlet: Oryx | Format: .PDF
We suggest that a radically different approach, something akin to human emergency response management (i.e., the Incident Command System) is one alternative to addressing the lack of cohesion and inertia in responding to amphibian issues. While we acknowledge existing efforts and the prodigious amount of useful research, we suggest that a change is warranted and that the identification of a new amphibian chytrid provides the impetus for such a change.
How spatio-temporal habitat connectivity affects amphibian genetic structure
Authors: Watts AG, Schlichting P, Billerman SM, Jesmer B, Micheletti S, Fortin M, Funk WC, Hapeman P, Muths E, Murphy MA | Date: 2015 | Outlet: Frontiers in Genetics | Format: .PDF
Heterogeneous landscapes and fluctuating environmental conditions can affect species’ dispersal, population genetics, and genetic structure, yet understanding how biotic and abiotic factors affect population dynamics in a fluctuating environment is critical for species management. We evaluated how spatio-temporal habitat connectivity influences dispersal and genetic structure in a population of boreal chorus frogs (Pseudacris maculata) using a landscape genetics approach. We developed gravity models to assess the contribution of various factors to the observed genetic distance as a measure of functional connectivity. We selected (a) wetland (within-site) and (b) landscape matrix (between-site) characteristics; and (c) wetland connectivity metrics using a unique methodology. Specifically, we developed three networks that quantify wetland connectivity based on: (i) P. maculata dispersal ability, (ii) temporal variation in wetland quality, and (iii) contribution of wetland stepping-stones to frog dispersal. We examined 18 wetlands in Colorado, and quantified 12 microsatellite loci from 322 individual frogs. We found that genetic connectivity was related to topographic complexity, within- and between-wetland differences in moisture, and wetland functional connectivity as contributed by stepping-stone wetlands. Our results highlight the role that dynamic environmental factors have on dispersal-limited species and illustrate how complex asynchronous interactions contribute to the structure of spatially-explicit metapopulations.
ARMI 2014 Annual Update
Authors: Muths E, Grant EHC, Chestnut T, Sadinski W, Waddle H, Adams M | Date: 2015 | Format: .PDF
ARMI is uniquely qualified to provide information that is scalable from local to national levels and is useful to resource managers. Here we provide highlights and significant milestones of this innovative program. ARMI has now produced over 500 publications. We feature several in this fact sheet, but please visit our website (http://armi.usgs. gov) for additional information on ARMI products, to find summaries of research topics, or to search for ARMI activities in your area.
Spatial occupancy models for predicting metapopulation dynamics and viability following reintroduction
Authors: Chandler RB, Muths E, Sigafus BH, Schwalbe CR, Jarchow CJ, Hossack BH | Date: 2015 | Outlet: Journal of Applied Ecology | Format: .PDF
This project provides an example of how spatio-temporal statistical models based on ecological theory can be applied to forecast the outcomes of conservation actions such as reintroduction. illustrates how spatial occupancy models overcome many of the obstacles hindering the application of metapopulation theory for informing reintroduction efforts.Our spatial occupancy model should be particularly useful when management agencies lack the funds to collect intensive individual-level data.
Integrating Multiple Distribution Models to Guide Conservation Efforts of an Endangered Toad
Authors: Treglia M, Fisher R, Fitzgerald L | Date: 2015-06-30 | Outlet: PloS ONE | Format: .PDF
Species distribution models are used for numerous purposes such as predicting changes in species’ ranges and identifying biodiversity hotspots. Although implications of distribution models for conservation are often implicit, few studies use these tools explicitly to inform conservation efforts. Herein, we illustrate how multiple distribution models developed using distinct sets of environmental variables can be integrated to aid in identification sites for use in conservation. We focus on the endangered arroyo toad (Anaxyrus californicus), which relies on open, sandy streams and surrounding floodplains in southern California, USA, and northern Baja California, Mexico. Declines of the species are largely attributed to habitat degradation associated with vegetation encroachment, invasive predators, and altered hydrologic regimes. We had three main goals: 1) develop a model of potential habitat for arroyo toads, based on long-term environmental variables and all available locality data; 2) develop a model of the species’ current habitat by incorporating recent remotely-sensed variables and only using recent locality data; and 3) integrate results of both models to identify sites that may be employed in conservation efforts. We used Random Forests to develop the models, focused on riparian zones in southern California. We identified 14.37% and 10.50% of our study area as potential and current habitat for the arroyo toad, respectively. Generally, inclusion of remotely-sensed variables reduced modeled suitability of sites, thus many areas modeled as potential habitat were not modeled as current habitat. We propose such sites could be made suitable for arroyo toads through active management, increasing current habitat by up to 67.02%. Our general approach can be employed to guide conservation efforts of virtually any species with sufficient data necessary to develop appropriate distribution models.
Trends in Rocky Mountain Amphibians and the Role of Beaver as a Keystone Species
Authors: Hossack BR, Gould WR, Patla DA, Muths E, Daley R, Legg K, Corn PS | Date: 2015 | Outlet: Biological Conservation | Format: .PDF
Despite prevalent awareness of global amphibian declines, there is still little information on trends for many widespread species. To inform land managers of trends on protected landscapes and identify potential conservation strategies, we collected occurrence data for five wetland-breeding amphibian species in four national parks in the U.S. Rocky Mountains during 2002–2011. We used explicit dynamics models to estimate variation in annual occupancy, extinction, and colonization of wetlands according to summer drought and several biophysical characteristics (e.g., wetland size, elevation), including the influence of North American beaver (Castor canadensis). We found more declines in occupancy than increases, especially in Yellowstone and Grand Teton national parks (NP), where three of four species declined since 2002. However, most species in Rocky Mountain NP were too rare to include in our analysis, which likely reflects significant historical declines. Although beaver were uncommon, their creation or modification of wetlands was associated with higher colonization rates for 4 of 5 amphibian species, producing a 34% increase in occupancy in beaver-influenced wetlands compared to wetlands without beaver influence. Also, colonization rates and occupancy of boreal toads (Anxyrus boreas) and Columbia spotted frogs (Rana luteiventris) were ≥2 times higher in beaver-influenced wetlands. These strong relationships suggest management for beaver that fosters amphibian recovery could counter declines in some areas. Our data reinforce reports of widespread declines of formerly and currently common species, even in areas assumed to be protected from most forms of human disturbance, and demonstrate the close ecological association between beaver and wetland-dependent species.
Modeling habitat connectivity to inform reintroductions: a case study with the Chiricahua leopard frog
Authors: Jarchow CJ, Hossack BR, Sigafus BH, Schwalbe CR, Muths EL | Date: 2015 | Outlet: Journal of Herpetology | Format: .PDF
Managing a species with intensive tools like reintroduction may focus on single sites or entire landscapes. For vagile species, long-term persistence will require colonization and establishment in neighboring habitats. Thus, both suitable colonization sites and suitable dispersal corridors between sites are required. Assessment of landscapes for both requirements can contribute to ranking and selection of reintroduction areas, thereby improving management success. Following eradication of invasive American bullfrogs (Lithobates catesbeianus) from most of Buenos Aires National Wildlife Refuge (BANWR; Arizona, USA), larval Chiricahua leopard frogs (L. chiricahuensis) from a private pond were reintroduced into three stock ponds. Populations became established at all three reintroduction sites, followed by colonization of neighboring ponds in subsequent years. Our aim was to better understand colonization patterns by the federally-threatened L. chiricahuensis, which could help inform other reintroduction efforts in the region. We assessed the influence of five landscape features on colonization. Using surveys from 2007 and information about the landscape, we developed a habitat connectivity model based on electrical circuit theory that identified potential dispersal corridors, after explicitly accounting for imperfect detection of frogs. Landscape features provided little insight into why some sites were colonized and others were not, results that are likely due to the uniformity of the landscape at BANWR. While corridor modeling may be effective in more complex landscapes, an approach more focused on local habitat is required at BANWR. We also illustrate that existing data, even when limited in spatial or temporal resolution, can provide information useful in formulating management actions.
Geographically Isolated Wetlands:
Authors: Mushet DM, Calhoun AJK, Alexander LC, Cohen MJ, DeKeyser ES, Fowler L, Lane CR, Lang MW, Rains MC, Walls SC
We explore the category geographically isolated
wetlands(GIWs; i.e., wetlands completely surrounded by
uplands at the local scale) as used in the wetland sciences.
As currently used, the GIW category (1) hampers scientific
efforts by obscuring important hydrological and ecological
differences among multiple wetland functional types, (2)
aggregates wetlands in a manner not reflective of regulatory
and management information needs, (3) implies wetlands so
described are in some way isolated, an often incorrect
implication, (4) is inconsistent with more broadly used and
accepted concepts of geographic isolation, and (5) has
injected unnecessary confusion into scientific investigations
and discussions. Instead, we suggest other wetland classification
systems offer more informative alternatives. For
example, hydrogeomorphic (HGM) classes based on wellestablished
scientific definitions account for wetland functional
diversity thereby facilitating explorations into
questions of connectivity without an a priori designation of
isolation. Additionally, an HGM-type approach could be
used in combination with terms reflective of current regulatory
or policymaking needs. For those rare cases in which
the condition of being surrounded by uplands is the relevant
distinguishing characteristic, use of terminology that does
not unnecessarily imply isolation (e.g., upland embedded
wetlands) would help alleviate much confusion caused by
the geographically isolated wetlands misonomer.