Introduction:
Vernal pools are a seasonal wetland ecosystem that provide habitat for numerous different types of organisms. They can be found in areas with Mediterranean climates, particularly in California, and in cooler areas in the Northeastern and Midwestern United States (1). These pools are able to hold water, because they contain bedrock or a hardpan (an impermeable clay layer) underneath them, which keeps the water from draining. Water is collected during the winter and spring when it rains, and gradually evaporates in the summer, often leaving the ecosystem completely barren for a period of time. Flowers begin to blossom in the spring and, as the water recedes, they continue to grow in colorful rings surrounding the remaining collection of water. Due to the constant changing levels of water, animals must be able to adapt to the aquatic and terrestrial ecosystem (2). Vernal pools are very fragile and sensitive to change, and we must implement new strategies to save what we can of these beautiful wetlands.
Benefits:
Vernal pools are very important, because they contain high levels of biodiversity. They provide habitats for numerous organisms, which include a lot of endemic species that cannot be found elsewhere (6). These unique species may be significant in scientific research, and future medical advancements and thus are important to protect. Vernal pools are also very aesthetically pleasing due to the plethora of beautiful flowers that blossom each year, and thus are great areas for recreational activities as well. Like other wetlands, they also play a role in the control of flooding and erosion, by gathering runoff and catching water and sediments (7). They are additionally able to help purify water by removing nitrates and other contaminants from agricultural runoff (7). Lastly, vernal pools assistant in reducing the amounts of carbon dioxide contained in the air, since the various flora that the ecosystem contains intake the harmful gas.
Historical State:
Vernal pools have been around for hundreds of thousands of years, and look very similar to how they did in the past, despite there being less of them today (8). Vernal pools typically range from about 10 square feet to 2.5 acres, although there are some that span up to 90 acres (6). Due to their varying sizes, some individuals make a distinction between them by referring to smaller pools as vernal swells, while larger ones as vernal lakes. Although their sizes differ drastically, they all have relatively shallow waters, usually no more than a few feet deep. Vernal pools generally occur in areas that are relatively flat but have small changes in elevation. In Southern California, vernal pools generally occur near each other because of the typography they require (1). The locations of vernal pools are greatly varied; they may occur in low areas of forests, vegetated wetlands, or open fields (9). Much of the essential, surrounding woodland areas have been destroyed over the years, greatly impacting many of these pools (5).
Vernal Pools: Spring
Vernal pools are seasonal, thus they are only blossoming with flowers during a few months of the year, typically spring, and are otherwise quite barren. Additionally, the plants are annuals, and therefore sprout and die each year. Unfortunately, many of the species of plants and animals associated with vernal pools are endangered or threatened.
Vernal Pools: Summer (Dry Phase)
Vernal Pools: Disturbed Soil
Human Impacts: “Ugly State” of Vernal Pools
Most vernal pool ecosystems have been lost due to human activities, particularly in California, where it is estimated that more than 90% of the vernal pool habitat has already been destroyed (3). This was largely due to Spanish colonizers devastating much of the historical habitat through agricultural growth, particularly in the Central Valley (3). This continues to be a problem today, as farmers expand onto these lands. Additionally, these areas are getting polluted due to the substances that are used in these agricultural processes. Runoff containing herbicides, pesticides, and fertilizers flow into these areas disturbing wildlife, and worsening the quality of water (4). Many plants are often unable to grow because of the toxic chemicals, and animals that rely on the water for biological processes are harmed. Vernal pools also come into contact with toxic substances, as many people leave trash and unwanted appliances in these areas (6). In many instances, the water levels of these pools are changing due to human activities, completely altering the ecosystem. High water demands by neighboring communities cause the water levels to lessen, and logging in nearby areas allows the ecosystem to hold less water (4).
Endangered Species: California Tiger Salamander
We continue to destroy these ecosystems through development and urbanization. As we build houses, resorts, and other structures we demolish the habitats of many organisms, making it harder for them to get the resources they need, and causing some populations to get completely wiped out. The building of roads also has very significant impacts, even in areas that are relatively free of development, as they can cause habitat fragmentation (4). Habitat fragmentation, the isolation of different areas of the same ecosystem, similarly makes it harder for organisms to get the nutrients they need to survive. This circumstance can reduce genetic diversity if members of the same population can no longer make contact with one another, making it more difficult for these organisms to adapt to environmental changes. Certain recreational activities are also very damaging to the environment, particularly driving off-road vehicles in these regions. This activity often results in soil being displaced, which makes the land more susceptible to erosion, and pushes plant seeds further into the ground making it more difficult for them to grow (6).
Table: Sensitive Plant and Animal Species by Vernal Pool Region
Likely Future Prospects:
Although we have lost a substantial amount of our vernal pool acreage, there are current regulations and efforts to prevent continuous loss and degradation. There are a few federal laws and policies that aid in minimizing the damage done to vernal pools. The “no net loss” of wetlands policy in the U.S. strives to maintain the current acreage of wetlands, which is achieved under certain regulations, consequently benefiting vernal pools. For example, under the Clean Water Act, some vernal pools that are connected to streams or waterways are regulated, keeping their waters cleaner (11). Many vernal pools are considered critical habitats under the Endangered Species Act, yet this does not provide any sort of protection for these areas. However, because of this designation, the U.S. Fish and Wildlife Service is working on implementing a recovery plan for many vernal pool ecosystems in California (3).
Table: Vernal Pool Conservation Sites
In 1995, the U.S. Environmental Protection Agency gave the California Department of Fish and Game funds to map vernal pools in different regions in order to begin the process of conservation (10). This has been beneficial in helping non-federal agencies locate lands in order to conserve. The Jepson Prairie Reserve of Solano County, which is regulated by the Solano Land Trust, spans 2,500 acres and contains some of the best remaining vernal pools in the state (12). However, a major problem is that most vernal pools are located on lands that are privately owned (6). These areas are therefore subject to continuous development and destruction that cannot be stopped. The future of these areas is not looking good, unless actions are taken soon.
Vernal Pool: Destruction due to Construction
Improvements:
Measures must be implemented to prevent developers from further encroaching on surrounding areas, and destroying the habitats of many organisms. This can be achieved by requiring developers working near vernal pools to have very detailed plans, and restricting the use of heavy machinery to certain zones in the area to minimize damage (3). It is also necessary to prevent the dumping of trash and harmful materials in these areas, as well as forbidding the use of off-road vehicles and bikes. This would be very beneficial to the sprouting of many vernal pools, and can be achieved by having individuals patrol the public areas, and even closing off some of these areas for a period of time. Additionally, the government should prohibit the use of chemical pesticides and herbicides in agricultural areas located within a certain radius of vernal pools.
An important step toward helping maintain, or even improving the current status of vernal pools, is through education of the ecosystem. As people become more aware of the importance of such habitats and the critical states of many of these areas, they will be less inclined to further damage them. Additionally, more people may be willing to help in preservation and restoration efforts as they realize the need to take immediate action. Although spreading awareness is significant, more direct action must be taken to help ameliorate the quality of these ecosystems. Through continued research and monitoring of the species within the ecosystem, we can learn more about what is needed to ensure the survival of particularly threatened organisms as well (3). The government can also try to purchase privately owned areas that contain vernal pools, to ensure that they are properly taken care of.
Sources:
- "Vernal Pools." United States Environmental Protection Agency, n.d. Web. 23 Nov. 2015. <http://water.epa.gov/type/wetlands/vernal.cfm>.
- "Vernal Pool Animals." Vernal Pools. Pennsylvania Natural Heritage Program, n.d. Web. 23 Nov. 2015. <http://www.naturalheritage.state.pa.us/VernalPool_Animal.aspx>.
- "California's Vernal Pools." California Department of Fish and Wildlife, n.d. Web. 23 Nov. 2015. <https://www.wildlife.ca.gov/Conservation/Plants/Vernal-Pools>.
- "Vernal Pool Threats." Vernal Pools. Pennsylvania Natural Heritage Program, n.d. Web. 23 Nov. 2015. <http://www.naturalheritage.state.pa.us/VernalPool_Threats.aspx>.
- Wenning, Bruce. "Strategies to Protect Vernal Pools in the Built Environment: Raising Awareness." Ecological Landscape Alliance, n.d. Web. 23 Nov. 2015. <http://www.ecolandscaping.org/03/conservation/landscaping-strategies-to-protect-vernal-pools-in-the-built-environment-raising-awareness/>.
- "Introduction." Vernal Pool Recovery Plan. U.S. Fish & Wildlife Service, n.d. Web. 23 Nov. 2015. <http://www.fws.gov/sacramento/es/Recovery-Planning/Vernal-Pool/Documents/VP%20Introduction.pdf>.
- "Vernal Pool Conservation and Management." Vernal Pools. Pennsylvania Natural Heritage Program, n.d. Web. 23 Nov. 2015. <http://www.naturalheritage.state.pa.us/VernalPool_Management.aspx>.
- "Introduction to Vernal Pools." Sacramento Splash, n.d. Web. 23 Nov. 2015. <http://www.sacsplash.org/post/introduction-vernal-pools>.
- "Vernal Pool Sizes and Types." What Could a Vernal Pool Look Like? The Vernal Pool Association, n.d. Web. 23 Nov. 2015. <http://www.vernalpool.org/vpinfo_2.htm>.
- Vendlinski, Tim. "California's Vernal Pools: Accomplishments and Conservation Strategies." California Native Plant Society, n.d. Web. 23 Nov. 2015. <http://www.cnps.org/cnps/publications/fremontia/january_2000/3vendlinski.pdf>.
- "Federal and State for Protecting Vernal Pools in Pennsylvania." Vernal Pools. Pennsylvania Natural Heritage Program, n.d. Web. 23 Nov. 2015. <http://www.naturalheritage.state.pa.us/VernalPool_Regulation.aspx>.
- "Jepson Prairie Preserve." Solano Land Trust. Solano Land Trust, n.d. Web. 23 Nov. 2015. <http://www.solanolandtrust.org/JepsonPrairie.aspx>.
