NE1438: Hydropedology of Vernal Pool Systems
(Multistate Research Project)
Status: Inactive/Terminating
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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 northeast 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. One of the conclusions from our studies was that although vernal pools occur throughout the northeast, at a regional level we have a very limited understanding of these wetlands. In this project we will study a range of vernal pools throughout the northeast region.
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 pools 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 analysis 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. Such analysis will allow us to model the effects of climate change on seasonal pond wetlands in the northeast.
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.
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 pools 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 analysis 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. Such analysis will allow us to model the effects of climate change on seasonal pond wetlands in the northeast.
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.