Recipient Organization
UNIVERSITY OF WYOMING
1000 E UNIVERSITY AVE DEPARTMENT 3434
LARAMIE,WY 82071-2000
Performing Department
Ecosystem Science and Management
Non Technical Summary
Vernal pools are one of the most ecologically valued types of inland wetlands. These ecosystems provide habitat for numerous rare and endangered plants and animals and provide numerous ecosystem functions within upland landscapes. By definition, vernal pools (sometimes known as seasonal ponds) are depressional wetlands that typically contain surface water during the dormant season (late fall or winter through spring) and for part of the growing season before drying during summer or early fall. In the northeast there are a range of different types of vernal pools including kettle holes, sink holes, Delmarva Bays, and oxbows. Over the last decade pedologists have been working together under multistate projects NE-1021 and NE-1038 to develop expertise in the identification, characterization, classification, and land use interpretations of hydromorphic soils in different types of wetlands.These studies are necessary because of a wide-range of stakeholder driven issues and concerns. Wetland identification, protection, and restoration is a multi-million dollar industry in the United States. State, regional, and federal agencies are working to develop and enforce regulations to maintain, enhance, increase, and protect our nations wetlands. Non-profit organizations such as The Nature Conservancy, Sierra Club, World Wildlife Fund, and Ducks Unlimited have joined forces to support many of these efforts. In contrast, economic development can be stymied by over-regulation and thus developers argue for a balance between natural resource protection and development. In between these arguments are often the small isolated wetlands known as vernal pools that have already suffered serious loss (some regions report as much as a 90% loss of vernal pool wetlands, mostly due to draining for agriculture). Although many states protect vernal pools in their wetlands regulations, federal protection under the Clean Water Act is limited because these systems are often not connected at the surface to the larger wetlands. Thus, showing a connectedness to the regional hydrology could be an important issue regarding their protection.The value of vernal pool ecosystems is registered in a range of functions. These are isolated wetlands on the landscape. Thus, they often hold the last remaining combination of plants and animals that represent the original ecosystem. For example, amphibians such as wood frogs and spotted salamanders require seasonal ponds to breed and develop. These herps lay their eggs in the ponds during the spring where the young develop into adults. As adults, they move into the surrounding uplands. If the ponds are dry all year they cannot breed, but if the ponds stay inundated all year (a pond/lake) fish will survive and eat the frog and salamander eggs and larval stages. Development of the young requires a duration of surface inundation, known as a hydroperiod, which varies in time depending upon the pool size and seasonal precipitation. Because there is generally a high degree of temporal heterogeneity in length of time pools are inundated within a watershed, and the factors governing the timing of surface inundation are poorly understood, developing an understanding of vernal pool hydroperiod across the landscape and region is necessary. We propose to measure hydroperiods in these studies and develop and test not only hydric soil indicators for these soils and landscapes, but also assess if inundation indicators can be developed for vernal pool wetlands to predict hydroperiods.In addition to temporal heterogeneity in pool hydroperiod, there is considerable spatial variation in densities of vernal pools across a region. What factors control spatial distribution of vernal pools is unclear. This could be a function of the type of vernal pool. For example, Delmarva Bays generally occur in groups within a specific range in elevation, but beyond that range, the bays are absent from the landscape. In this project we will test spatial tools such as terrain or image analysis to map and quantify the size, shape, and density of vernal pools across landscapes of the region. This is important because at the scales of most soil surveys and NWI maps, vernal pool wetlands are often missed. These analyses will also be used to estimate the extent that vernal pools that have been altered (mostly drained) to identify the number of vernal pool wetlands that have been lost (or potentially able to be restored.Hydroperiod is clearly a function of climate and hydrology. Our studies will provide a 5 year record of the hydrology of a range of vernal pools across the region. These data can be used to set hydrologic goals for the restoration of vernal pools and assess the effects of future climate change on hydroperiod of these ecosystems. In addition, we will use analysis of long-term climate data to assess relationships between climate and hydrology. Our previous studies of carbon pools (stocks) has shown that kettle holes (glacially derived vernal pools) contain the largest carbon pools on the landscape (over 600 Mg/ha in the upper meter of the soil). There are no region-wide studies, however, that show these same trends in non-glaciated regions. Since vernal pool ecosystems include areas that are inundated adjacent to those that are only seasonally saturated to the surface we can test the effect of inundation on the accumulation of carbon. We will monitor redox conditions within the vernal pools to develop relationships between carbon pools, flux, and cumulative anaerobic conditions. We will examine spatial variability in carbon accumulation using ground penetrating radar and electromagnetic induction. We can use these data to establish models to predict the effects of climate change (increases or decreases in precipitation and temperature) on carbon storage and flux in the soils of vernal pools.
Animal Health Component
50%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
0%
Goals / Objectives
Improve our understanding at a regional scale of how vernal pool ecosystems differ in distribution, hydrology, hydroperiod, redox chemistry, and carbon storage and flux. Along with this we will develop a better understanding of the effects of hydrology and temperature on carbon pools and sequestration in wetlands along a temperature gradient.
Develop morphometric indices of the hydroperiod within vernal pools.
Project Methods
Spatial Distribution and AnalysisUsing GIS technology and available imagery, estimates will be made of the size, shape, and density of vernal pools across landscapes.Where possible, these data will also be used to evaluate the extent to which vernal pools may have been altered (drained or filled). These analyses may permit estimation of the number of vernal pool wetlands that have been lost or those that may potentially be restored.Plot Layout and Experimental DesignIn the wetland at each study site (one study site in Wyoming), 3 hydrological zones will be identified, corresponding to the predominant soil, plant, and water characteristics at each location (Figure 1). Zone 1 is seasonally ponded, and typically contains emergent, shrub or woody vegetation. Zone 1 usually becomes ponded in the Winter and early Spring and then dries out sometime before or during the Summer season. Zone 2 is a wetland transitional zone marked by saturation, but not significant ponding. Wetland vegetation and hydric soils are expected to be present in zone 2, as in zone 1. Zone 3 is the upland area beyond the wetland boundary. Hydric soils will not be present in zone 3, although in some cases hydrophytic vegetation can be observed adjacent to, and outside the boundary of, these wetlands.Within each site, nine research plots will be laid out along three transects. Each of the transects will extend radially outwards from the center of the vernal pool (zone 1) through zone 2 and into the upland. Along each transect, a single plot will be centrally located within each of the hydrological zones. Location of the transects will be randomized based upon compass orientation. Elevation will be determined along each transect using appropriate tools such as a level or total station. Microtopographic differences will be documented by recording elevations at 1 meter intervals along the transects.Hydrological MeasurementsThe depth of ponded water or the depth to the water table (below the surface) will be recorded at each site. Depth of ponded water will be measured using a staff gauge. Monitoring ports consisting of a well screen installed to a depth of 100 cm will be placed at each plot and water tables will be measured periodically. Along a single transect at each site, water table recording devices will be installed and programmed to record water table levels twice each day. The detailed (daily) data set from the recording devices will be extended to the other transects based on the periodic observations in the monitoring ports. Also along a single transect, nests of piezometers will be installed to help with interpretation of hydrological flow patterns.Soil Morphological DescriptionsIn the vicinity of each plot, a soil profile description will be made to a depth of 1 to 2 m according to standard protocols (Schoeneberger et al., 2012). Soil will be examined using a bucket augur. Horizons will be delineated and soil properties (texture, color, and presence of redoximorphic features) will be described in the field. Samples collected from each horizon will be stored for laboratory analysis. Morphological descriptions will be compared with approved field indicators of hydric soils to determine whether there is any need for additional hydric soil indicators for use in vernal pool ecosystems (USDA-Natural Resources Conservation Service, 2010).Vegetation AnalysisPlant communities in each of the three zones will be assessed by methods outlined in the 1987 USACOE Wetland Delineation Manual (U.S. Army Corps of Engineers Environmental Laboratory, 1987) and the appropriate regional supplement (USACE, 2010, USACE, 2012, USACE, 2012).Quantifying Carbon and Nitrogen StocksCarbon and nitrogen stocks will be determined at plots along each transect (Vasilas et al., 2013). Within each plot, a section of aluminum tubing (sharpened on the leading edge) (60 cm long and 5 cm diameter) will be driven 50 cm into the soil. The tube will then be excavated and capped. Upon return to the lab, cores will be frozen to assist in extrusion. The extruded cores will be divided into vertical sections based on observed soil horizons, and the thickness of each horizon will be carefully measured. All soil material from each horizon will then be homogenized and weighed. The bulk density of each horizon will be then be calculated as the weight of the horizon divided by the horizon volume (calculated from the thickness of horizon multiplied by the cross-sectional area of the tube). The soil organic C percentage will be determined using a homogenized subsample of each horizon. Total carbon will be determined in duplicate by dry combustion (Nelson and Sommers, 1996) using a high temperature CNH Analyzer with an IR detector. These data will be used in conjunction with measurements of horizon thickness and bulk density to calculate the total C stocks in the soil to a depth of 50 cm.Soil Redox AssessmentIRIS (indication of reduction in soil) tubes will be used to assess the reducing soil conditions within each plot (Rabenhorst, 2008; Rabenhorst and Burch, 2006; Rabenhorst et al., 2008; Vasilas et al., 2013). Five replicate IRIS tubes will be inserted at each plot to a depth of 50 cm. IRIS Tubes will be installed for a one month period in the Spring when water tables are expected to be high. The installation date at each site will be within one week of the beginning of the growing season as determined by US Army Corps of Engineers guidance (USACE, 2010; USACE, 2012; USACE, 2012). The extent of reduction on IRIS tubes will be determined by assessment using a mylar overlay (Rabenhorst, 2012).Organic Matter DecompositionThe relative rates of organic matter decomposition will be evaluated by inserting wooden sticks into the soil and then extracting them at fixed intervals and measuring mass loss over time. Other studies have shown that wooden sticks can be used to indicate organic matter decomposition rates in several different types of settings (Baker, Lockaby, et al., 2001, Gulis, Rosemond, et al., 2004, Ostertag, Marín-Spiotta, et al., 2008). We will use northern white birch (Betula papyrifera) garden stakes that are approximately 300 x 16 x 3 mm in size. The stakes will be pre-dried (60C for 3 days to achieve constant weight) and weighed before being inserted vertically into a pilot hole in the soil, and then extracted at pre-determined intervals. The rate of decomposition will be estimated from differences in the starting and ending weights. Five replicate sticks will constitute a set. Five sets of pre-weighed sticks will be installed at each plot during the late Fall (November - December). One set of sticks will be removed each quarter (3 months intervals). When removed, the sticks will be gently washed to remove any attached soil material and then re-dried before being weighed. Overall weight loss will be determined by comparison of initial and final weights.Data AnalysisData will be subjected to an analysis of variance (ANOVA) using either PROC ANOVA or PROC GLM of the SAS System, Version 9.1.3 (SAS Institute, Inc., 2004) as a complete data set and then by regional group as warranted. When indicated by the ANOVA F-Test, means will be separated by the use of Duncans New Multiple Range Test, or other appropriate mean separation procedure. An Analysis of Covariance may be employed to determine differences in time series date for each site and between sites as appropriate. Additionally multiple regression may be employed to create prediction models for various data, i.e. decomposition rate as influenced by climate variables and soil properties. Ordination analysis will be undertaken as necessary when needed to better interpret the data.