Forest Service, Climate Change and Aquatics

Symposium

Organizers: Dixie Porter, Brian Logan, Anne Marsh, Patty Klein, Tracy Grazia, Brice Hanberry, and Mary Rowland

Supported by: USDA Forest Service,

In 2011, the U.S. Forest Service (USFS) implemented the first “Climate Change Performance Scorecard” (Scorecard) for all national forests and grasslands across the nation encompassing 193 million acres and the Scorecard was expanded in 2020. Climate change, including increased temperatures, variable precipitation, and extreme events, is expected to disrupt the composition of plant and animal communities and destabilize existing ecosystems. Climate change will affect resources, such as water, food, cover, and breeding habitat, resulting in reduced survival, growth, and reproduction of wildlife. Over longer time periods, vegetation shifts may disorder current assemblages as species respond uniquely in distribution and abundance. Species may respond to habitat changes by adapting within their current range, shifting to new distributions, or by decreasing population sizes in isolated and increasingly contracting refugia. Wildlife will face climate-related challenges through habitat loss or degradation, fragmentation and connectivity issues, phenological changes, extreme weather and related disturbance events, physiological stress and increased vulnerability to disease, and disordered interspecific relationships. Interactions will likely result in a cascade of stressors because poorly nourished animals are less resistant to drought, temperature fluctuations, fire, land use pressure, insecticides, and disease. Climate change may favor generalist and non-native species, possibly resulting in lower biodiversity. Consideration of the myriad of climate change effects on wildlife, resources, and ecosystems when developing wildlife management plans will benefit wildlife and the ecosystems that support wildlife. These four sessions will highlight national and regional approaches using the Climate Scorecard and collaborations with the USDA Climate Hubs and provide examples of work the Forest Service is doing to identify climate change vulnerabilities, develop adaptive management strategies, and address challenges in aquatic systems. We will provide information on how the Forest Service is tracking progress on climate change using its Scorecard and supporting land managers through the USDA Climate Hubs.

 
Climate Services in Support of Forest Planning and Wildlife Management in the US Forest Service
Charles Luce, Erik Johnson, Nathan Walker, Daniel Isaak
As climate changes, the US Forest Service is taking how the climate is expected to change into consideration when developing Forest Plans and Project Plans.  Consideration of Climate Change is a requirement of the 2012 planning rule, and there is a need for authoritative, easily accessed, and easily applied data and maps of expected changes for National Forest planners, watershed, fish and wildlife specialists, and interested stakeholders.  Broadly, increased carbon dioxide is warming air temperatures, leading to expectations for warmer streams, reduced snowpacks, increased wildfire risk, and altered streamflow characteristics.  Each of these, in turn is expected to have an effect on species distributions, biotic interactions, migration, and population viability.  Although some fish and wildlife species are more susceptible to the kinds of changes expected from climate change, most every species would be expected to have some response.  Indeed, some may well have a positive response in some locales.  In order to reasonably consider the impacts of climate change on fish and wildlife species, the USFS Office of Sustainability and Climate and researchers at the USFS Rocky Mountain Research Station have collaborated to provide mapped data of expected changes in temperature, precipitation characteristics, snowpack storage metrics, stream temperature measures, and a suite of streamflow metrics.  All calculations are based on well-vetted downscaling methods and snowpack, hydrology, and temperature models backed by substantial peer reviewed research.  The maps are updated as time and supporting data allow.  Climate and snowpack metrics are provided on 4-km grids while streamflow and temperature data are provided on National Hydrography Dataset stream segments.  The map resolution is intended to provide specialists and managers with enough information to understand general expectations of differences and variations in climate and water changes across important gradients in a National Forest System unit.  Ease of use is a key consideration.
 
Weather, Hydroregime, and Breeding Effort Influence Juvenile Recruitment of Anurans: Implications for Climate Change
Cathryn Greenberg, James Austin, Stanley Zarnoch
Amphibians that primarily breed in ephemeral wetlands are especially vulnerable to climate change because they rely on rainfall or temperature to initiate breeding and create suitable hydroregimes – duration and depth of water in wetlands – for reproductive success. Hydroregime effects on recruitment are likely to differ among species according to the length and timing of breeding periods, rates of larval development, and timing of metamorphosis (reproductive strategies). We used 22 consecutive years of continuous amphibian trapping data at eight ephemeral wetlands to test hypotheses regarding environmental and biological factors affecting juvenile recruitment (JR). Our subjects included six species representing four reproductive strategies. The best model for all species except Scaphiopus holbrookii indicated that >1 hydroregime variable or total precipitation, or both were important drivers of reproductive success; average air temperature was not. Continuous hydroperiod through peak juvenile emigration was an important JR predictor for species with prolonged breeding periods, slow larval development, and a “fixed” start date for juvenile emigration (Lithobates capito; L. sphenocephalus), but not for species with rapid larval development and continual emigration as cohorts complete metamorphosis (Anaxyrus terrestris, A. quercicus, S. holbrookii, Gastrophryne carolinensis). Total rainfall was positively associated with recruitment for most species; depth characteristics affected species differently. Annual JR was positively correlated among species with similar reproductive strategies. Our results indicate that weather and hydroregime characteristics interact with reproductive strategies that differ among amphibian species and influence reproductive plasticity, opportunity, and success. Effects of altered weather patterns associated with climate change on amphibian reproductive success may correspond more closely among species having similar reproductive strategies, with critical implications for population trends and assemblages.
 
Climate-Niche Space Associations of Global Detections of the Amphibian Chytrid Fungus Batrachochytrium Dendrobatidis Support Conservation Urgency
Dede Olson, Kathryn Ronnenberg, Kelly Christiansen, Caroline Glidden, Andrew Blaustein
With burgeoning knowledge of amphibian disease threats over the last three decades, a challenge emerged to keep abreast of current information. Development of globally accessible online pathogen databases has been a boon to both science and management. In 2007, we compiled Batrachochytrium dendrobatidis (Bd) data for the Global Bd Mappting Project, which then became the founding database of Bd-maps.net, the first amphibian pathogen web portal. Bd-maps data has now merged into AmphibiaWeb’s Amphibian Disease Portal: https://amphibiandisease.org. These portals have provided novel opportunities for pattern assessment such as understanding pathogen climate-niche space. We recently compiled new informaiton on world Bd detections, assessing taxonomic and geographic patterns, and examining environmental association of Bd occurrences including its climate associations. Bd has been detected in 1375 of 2525 (55%) amphibian species, in 93 of 134 (69%) countries. Using both detection and no-detection data and detection-only data in species-distribution models at global scales, climate metrics were highly associated with Bd occurrence. In global models with detection-only data, mean annual daily temperature accounted for the highest fraction of total variation in probability of Bd occurrence (0.71), and annual precipitation accounted for the next highest fraction (0.21). In global models with both detection and no-detection data, mean temperature was the key predictor of Bd occurrence (0.97). In downscaled analyses conducted at continental scales, these two climate parameters retained importance but different models resulted including a broader array of predictors such as maximum elevation (Africa) and temperature range (Australia). Downscaled models at finer spatial resolutions are warranted to guide local climate-smart management actions to forestall potential Bd-disease threats to local fauna, especially for endemic and rare species and in areas serving as strongholds for unique amphibian communities. As 40% of world amphibians are vulnerable to extinction, management of main threat factors including disease-causing pathogens has conservation urgency.
 
Potential Implications of Sea Level Rise for Persistence of a Recently Described, Burrowing Crayfish Species Narrowly Distributed Near the Gulf of Mexico.
Susan Adams, Mael Glon
Lacunicambarus freudensteini, the Banded Mudbug, is a recently described, primary burrowing crayfish that occupies a narrow band in two coastal counties in Alabama and Mississippi. Its distribution appears to be restricted by a congener, L. mobilensis, the Lonesome Gravedigger, to the north, the Pascagoula River to the west, Mobile Bay to the east, and the Gulf of Mexico to the south. The species is known from 8 sites, some of which yielded a single specimen, and it was not found at 7 other sites within its range, although other burrowers were plentiful. Some of the species’ localities are at low elevations within several km of the Gulf of Mexico. A sea level rise of 2 m—predicted by some models—would inundate some of the localities. However, given its burrowing habits, sea level rise and soil salinization may affect the species’ distribution even before any of its localities are fully inundated. We will present spatial modeling results of the risks of various degrees of sea level rise to the species, outline some of the major modeling and ecological uncertainties, and offer suggested approaches to addressing the ecological uncertainties.
 
Going with the Flow: Beaver-Related Stream Restoration on Western Rangelands
Holly Prendeville, Caroline Nash, Grant Gordon, Susan Charnley, Jason Dunham, Hannah Gosnell, Mark Hausner, David Pilliod, Jimmy Taylor
Beaver-related restoration is a process-based strategy increasingly being used to restore degraded stream systems and associated riparian areas by facilitating dam building. Beaver-related restoration has broad appeal as a climate change adaptation option that may lead to a host of desired outcomes ranging from creating mesic habitats in arid landscapes to increased carbon storage, yet its effectiveness is not well documented. We present a process-expectation framework that identifies commonly expected outcomes from three types of beaver-related restoration, and then lists the set of natural processes (e.g., dam building, water and sediment impoundment, groundwater level rise) that must occur to achieve these outcomes. Analysis of relevant literature and several implemented beaver-related restoration projects suggests that project outcomes are often dependent on complex process pathways over which humans have limited control. To evaluate effectiveness of future beaver-related and other process-based restoration projects, we suggest that practitioners identify relevant processes that need to occur for success in advance, and document how projects do or do not proceed along expected process pathways. Both quantitative and qualitative data derived using formal monitoring protocols and from the observations of project participants are valuable in this regard. Land managers and practitioners can use this process-expectation framework to inform adaptive management as they plan, implement, and monitor beaver-related restoration. Practitioners can apply the framework to further their climate change adaptation goals and National Forest managers can use it to advance their Sustainability Scorecard achievements. 
 
Shrinking Headwaters with Climate Change Affect Salamander Habitat in Western Oregon
Dede Olson, Julia Burton
Integrating climate-smart principles into riparian-and-upland forest management can facilitate efficient land use and conservation planning. Emerging values of forested headwater streams can help forge these links, yet climate effects on headwaters are little studied. We assessed associations of headwater discontinuous streams with climate metrics, watershed size, and forest-harvest treatments. We hypothesized that summer streamflow would decrease in warm-dry years, with possible harvest interactions. We field-collected streamflow patterns from 65 discontinuous stream reaches at 13 managed forest sites in western Oregon, USA over a 16-year period. We analyzed spatial and temporal variability in field-collected stream habitat metrics using non-metric multidimensional scaling ordination. Relationships between streamflow, climate metrics, basin size, and harvest treatments were analyzed with simple linear models and mixed models with repeated measures. Using past effects of climate variation on streamflow, we projected effects to 2085 under three future scenarios, then quantified implications on headwater networks for a case-study landscape. Ordination identified percent dry length of stream reaches as a top predictor of spatial and temporal variation in discontinuous stream-habitat types. In our final multivariate model, percent dry length was associated with heat:moisture index, mean minimum summer temperature, and basin area. Across future climate scenarios in years 2055-2085, a 4.5-11.5% loss in headwater surface streamflow was projected; this resulted in 597-2058 km of additional dry channel lengths of headwater streams in our case study area, the range of the endemic headwater-associated Cascade torrent salamander (Rhyacotriton cascadae) in the Oregon Cascade Range, a species proposed for listing under the US ESA. Implications of our study for proactive climate-smart forest-management designs in headwaters include restoration to retain surface flows and managing over-ridge wildlife dispersal habitat from areas with perennial surface water flow, as stream reaches with discontinuous stream flow currently were projected to have reduced flows in the future with climate change.
 
Impacts of Sea Level Rise on the Habitat Value of Pacific Island Mangrove Forests
Richard Mackenzie, Maybeleen Apwong, Kevin Buffington, Karen Thorne, Ken Krauss
Mangrove forests provide habitat for wildlife and fish, as well as critical ecosystem services that support local communities. The biggest future threat to mangrove forests in the western Pacific is increased rates of sea-level rise (SLR), yet it is unclear how mangroves in this region will respond and how mangrove response will impact its habitat value and the wildlife that relies on it. We developed a generalizable modeling framework that accounts for both tree species interactions and the belowground processes that influence elevations in mangroves on the island of Pohnpei, Federated States of Micronesia. The model was calibrated with field datasets; soil cores, forest plots, water loggers, and elevation surveys. The responses of elevation and the mangrove community composition were analyzed under four global SLR scenarios (37, 52, 67, and 117 cm) by 2100 for seven regions of the island. Results showed that mangroves can build their elevations relative to moderate rates of SLR to prevent submergence, with limited changes on mangrove community composition through 2060. Under higher SLR, forest elevation decreased substantially with more drastic changes in the tree community composition and loss of mangroves by 2100. Variation in accretion rates, water levels, and initial forest elevation led to different vulnerability around the island, with mangroves on the leeward side generally the most at-risk to higher rates of SLR. The potential impacts of these forest structure changes on habitat and wildlife will be further explored in this presentation.
 
Impacts of Changing Rainfall Regimes on the Ecological Function of Pacific Island Streams
Richard Mackenzie, Ayron Strauch, Ralph Tingley, Therese Frauendorf, Michael Riney, Patra Foulk, Christian Giardina, Gregory Bruland, Dana Infante
Stream flow is a critical component that provides the habitat needed by unique assemblages of amphidromous shrimp, fish, and snails that are characteristic of tropical Pacific Island streams. Intact streams and stream flow also allow these organisms to complete their amphidromous lifecycle by migrating to and from the ocean. Changes in stream flow from dams and diversions, increased spread of high water use invasive species, and decreased rainfall anticipated to occur under future climate threaten the stream habitat of these organisms, their overall existence, and thus the ecological function of tropical island streams. We used a model system consisting of 12 streams located across a naturally occurring 3500 mm rainfall gradient while all other factors were held constant (e.g., air temperature, substrate, vegetation) on Hawaii Island as a model system to examine how decreasing rainfall would impact the ecological, hydrological, and biogeochemical function tropical streams. Decreasing rainfall reduced stream flow, flashiness, and water quality and increased flow variability. This reduced food quality and quantity, shifting organic matter food resources from high quality vascular plant and benthic algal matter to low quality leaf litter. This impacted the food web structure of native atyid shrimp across the gradient, which are a keystone species of tropical Pacific islands streams and that relies heavily on benthic algae scraped from rocks as a food resource. This shift in food resources resulted in reduced shrimp egg output and as well as body condition. Information will increase our ability to more effectively restore and conserve streams in Hawaii and elsewhere in the Pacific.

Symposium
Location: Virtual Date: November 5, 2021 Time: 3:00 pm - 4:00 pm