Recipient Organization
UNIVERSITY OF FLORIDA
G022 MCCARTY HALL
GAINESVILLE,FL 32611
Performing Department
Wildlife Ecology and Conservation
Non Technical Summary
Climate is the most basic denominator across the Earth in determining where species occur today. This is because species distributions are a product of the relationship between environmental exposure and species sensitivity. A species is adapted to its environment because it possesses traits (physiology, behaviour, resilience, etc.) that allow it to survive under constraints such as climate and/or habitat.Biodiversity in mountain systems are often layered in bands spanning from the warm lowlands to cool uplands. Tropical mountain systems contain many species that are adapted to a narrow range of atmospheric conditions across space such that there is little overlap between the thermal regimes faced by organisms living at different elevational zones. This is in direct contrast to species living in temperate zones that experience wide variation in temperature due to seasons. Importantly, due to severe geographic isolation, many high elevation communities are expected to be highly dependent on habitat features and traits to survive future climate change.Future climate warming will likely favor species with high ecological and behavioral plasticity and broad tolerances to thermal regimes. One such trait is tree living (arboreality). Arboreality is an important component for understanding current species distribution and past and future climate change impacts on biodiversity as it inherently incorporates ecophysiology, habitat use, behavior, and adaptive capacity to tolerate thermal stress (Scheffers et al. 2013 Proc. R. Soc. B). There is increasing evidence that species behavior (microhabitat preferences, in the case of our proposed study) and its interaction with thermoregulatory requirements and the surrounding microclimatic environment will help mediate the negative impacts of environmental instability across space and time.In this study, my goal is to comprehensively assess how climate change will affect species living on mountains in temperate forest ecosystems. I will achieve this by documenting species multidimensional distributions (i.e., elevational and vertical [i.e., within trees]) and relating them to fine-scale climate (i.e., environmental exposure) and species' physiology (i.e., sensitivity).
Animal Health Component
40%
Research Effort Categories
Basic
60%
Applied
40%
Developmental
(N/A)
Goals / Objectives
Goals, Objectives and HypothesesMy proposed research program will explore drivers of biological organization in space and time and the effects of human disturbance on these processes in temperate forests. This will encompass multiple taxonomic groups with emphasis on major research themes that include multidimensional species distributions in the canopy of forests, ecophysiology of ectotherms, microhabitat buffering in structurally complex environments and extreme climate events. This proposed research program converges under a single theme - assessing species and habitat vulnerability and resilience under global change (i.e., novel climates and disturbances).In this study, my goal is to comprehensively assess how climate change will affect species living on in the lowlands and upland mountain forest ecosystems. I will achieve this by documenting species multidimensional distributions (i.e., elevational and vertical [i.e., within trees]) and relating them to fine-scale climate (i.e., environmental exposure) and species' physiology (i.e., sensitivity) and evolutionary history.My program proposes four objectives that use field-based data collection (obj. 1-3) to assess species' vulnerability to climate change. The combined results of obj. 1-3 will inform a novel conservation planning scheme (obj. 4) for the temperate forest ecosystems of the southeastern USA.Objective 1.My Obj. 1 is to document the vertical distribution of species living within forests and across elevation to better understand broad scale multidimensional patterns of species richness and abundance. Across mountain sites, we will use standardized techniques to sample fossorial, ground, and arboreal frog, reptile and butterfly species.Hypoth. 1: Based on past research on microhabitat preference (Brown & Gonzalez 2007; Scheffers et al. 2013b), I hypothesize that arboreal species will be dominant at higher elevations and will exhibit increased levels of arboreality at higher elevations (due to cooler temperatures).If I confirm Hypoth. 1, through space-time substitutions (high elevation = current, low elevation = future), I predict that climate warming will likely 'flatten' the verticality of forest communities as species shift downwards towards the cooler ground.A plausible mechanistic link between microhabitat preference and in situ persistence under climate fluctuations can be derived from Janzen's (1967) hypothesis--that a temperate lowland organism is likely to move over a mountain pass because it has high chances of encountering temperatures it has been exposed to owing to seasonality.Objective 2.In Obj. 2, I propose to extend Janzen's hypothesis by establishing long-term climate monitoring stations to examine the overlap in thermal regimes in soil, ground and canopy microhabitats from lowlands to uplands in both temperate forests. My preliminary analysis suggests that arboreal species are likely exposed to similar temperatures in the lowlands as in the uplands (high overlap) whereas ground species are seldom exposed to similar temperatures in the lowlands as in the uplands (low overlap).Hypoth. 2: I hypothesize that canopy temperatures at low elevations will share greater overlap with canopy temperatures at high elevation whereas ground and soil temperatures will share little overlap among low and high elevation sites.Objective 3.Arboreal species should have broader physiological tolerances due to greater exposure to extreme temperatures across space. In obj. 3, I will measure the minimum and maximum tolerable temperatures of frogs and lizards from different microhabitats across elevation. Preliminary results from other studies suggests that canopy frog species have thermal maximums that are ~3 °C higher than congeneric ground specialists. This provides provisional support that canopy species might be selected for under warmer temperature conditions.Hypoth. 3: I hypothesize that arboreal communities at low and high elevations will share more similar tolerable minimum and maximum temperatures than ground and soil communities at the same elevations. In the case of frogs, I further hypothesize that canopy frogs will exhibit less dehydration during the dry season and greater dehydration during the wet season than ground-dwelling frogs due to physiological adaptations (Tracy et al. 2010) and may result in decreased vulnerability.Objective 4.Lastly, in Obj. 4, I will create planning schemes to prioritize landscape conservation based on species vulnerabilities (obj. 1-3) to climate change, working closely with stakeholders at my sites and reporting directly to the central/local government of the residing region or USA state. This approach will provide stakeholders with a spatially-explicit prioritization of forest ecosystems across each region of study.
Project Methods
I will survey forest systems in Appalachian Mountains of Georgia and North Carolina and lowland deciduous-pine forests of Florida, USA.Taxonomic surveys (obj. 1): I will use ground surveys, canopy surveys, and pitfall traps to monitor frog and lizard populations across habitat and elevational transects. Surveys will be conducted every 200 m across elevation, spanning lower-, mid-, and upper forest types during day and night. Surveys will be time-constrained with fixed numbers of participants to ensure equivalent sampling effort and will be assessed with species-accumulation curves. I will use canopy survey techniques that we developed (Scheffers et al. 2013b) to sample canopy frogs and lizards. Four 10-m drift fence / pitfall trap arrays will be installed at each site. I will check traps daily.I will also sample butterflies and moths at the same location as our frog, salamander, and reptile surveys. I will use hand nets and binoculars to survey active butterflies in crepuscular (7:00am-10:00am and 3:00-6:00pm) and midday hours (10:00am - 3:00pm) in each habitat type and moths during nighttime hours. I will survey along 0.5 km transects for 30 minute intervals and I will mark each captured butterfly to avoid double counting. For those individuals not easily identified during sampling, I will collect a specimen for identification in the lab. All butterfly surveys will occur on the ground.NOTE: IACUC approval has been obtained for this project under IACUC permit # 201709756.Climate (obj. 2): I will install climate-monitoring stations at each survey site. I will measure temperature, relative humidity and light using HOBO Pendant data loggers. Soil loggers will be placed at ~7 cm in total depth. Above this, I will install stations at 1.5 m above ground and in the canopy (~19-25 m). All data loggers will be shielded from direct solar radiation. Data loggers will be downloaded on each field trip (~ every 6 months). Thermal heterogeniety of the forest environment will be sampled with thermographic infrared cameras.I will apply thermographic technology to capture temperature-space heterogeneity across structurally complex forest ecosystems. I will use two FLIR thermal infrared cameras (Model: E6 and Model E40; www.flir.com) to measure temperature in forest ecosystems. My E6 model records 19,200 samples of temperature per photo (160 x 120 pixels) whereas the E40 model records 76,800 samples per photo (320 x 240 pixels). I will take photos under variable conditions and all thermal photos will be taken with a standardized angle fixed at approximately 30 degrees from the ground and at approximately 1 m in height (i.e., waist height). At each sampling point across our locations, I will take four photos at North, East, South, and West directions, amounting to 76,800 (E6) - 307,200 (E40) temperature measurements per 3.6 x 4.4 m area. Sampling will occur during daytime hours from 0600-1700 hrs. Photos will span habitats with variable complexity (deciduous, pine and rainforest) and under variable weather conditions. At the same time, we will measure wet-bulb ambient air conditions via a hygrometer at 1m in height--a standard technique for sampling ambient air temperature in ecological studies. Wet bulb temperatures will be taken once at each sampling point and represent the lowest temperature that can be reached under current ambient conditions by the evaporation of water only.Physiology (obj. 3): The critical thermal maximum (CTmax) and minimum (CTmin) of ectothermic invertebrates and vertebrates provides a useful index for the thermal constraints of animals (Hutchison 1961; Scheffers et al 2013a). I will obtain upper and lower critical thermal tolerances via Hutchinson dynamic methods, whereby each individual will be exposed to a constant temperature increase/decrease of 0.5°C/min (in an incubator) until the individual loses righting ability. To determine the hydration state of each frog, each individual will be weighed, soaked in water for 10 min and then reweighed. The difference in pre- and post-soak weight determines hydration state, with a larger difference indicating greater dehydration.NOTE: IACUC approval has been obtained for this project under IACUC permit # 201709756.AnalysisHabitat preference: I will use a newly developed model based on the beta probability distribution to capture the full range of response curve patterns that emerge when distributions are bounded at both ends (i.e., ground to canopy). The two beta model shape parameters together describe range preference (ground to canopy) and specialization (specialist to generalist). These metrics will be compiled using abundance data for each species.Climate: I will plot the range of thermal regimes for each stratum (soil, ground, canopy) at each elevation and determine daily overlap values between the upland and lowland regimes for each stratum using the overlap value calculation as described in Janzen (1967). I will use script code written in R to batch process all thermographic photos (R Core Team; https://www.r-project.org/)Physiology: Thermal safety margins will be determined for each species. I will compare thermal tolerance limits (CTmax, CTmin) to maximum temperatures recorded at each stratum (Te-habitat) at each site of collection, to determine whether individuals have positive thermal-safety margins (i.e., CTmax > Te-habitat(max) and CTmin < Te-habitat (min)) or lack sufficient thermal tolerance to cope with extreme temperatures (CTmax < Te-habitat(max) or CTmin > Te-habitat(min) (Sunday et al. 2014). Species with negative thermal-safety margins must rely on access to refugia to survive during extreme events.Conservation Prioritization: I will integrate species distribution models (SDMs) into a spatial prioritization algorithm (software: Zonation; Moilanen et al. 2005) and weigh the strength of our prioritization by ranked traits correlated with climate resilience (ecological niche, elevation breadth, thermal safety margin), and/or the ability to recover after an environmental disturbance.