"If this is a wetland, where is the water?"
This is a common comment made when people look at this area of the Willie Mott Park and Wetlands. However, wetlands and ponds are different, and this wetland area does not always have a pond.
A wetland is different from a pond in that a wetland usually holds only shallow water and may not have water all the time. Wetlands store rainwater and slowly filter it into the ground instead of having the rainwater drain into streams and urban runoff. Water in the wetlands is cleaned by filtering through the soil and being taken up by wetlands plants. The marshy area provides habitat for a variety of birds, mammals, and amphibians. Wetlands areas also helps store carbon dioxide in the plants and soil instead of releasing it into the atmosphere.
The Bluegrass Downs Wetlands Project is a mitigated wetlands developed through a partnership with the City of Central Point and Oregon State Lands. It was developed as a result of the growth of housing subdivisions in this area.
Wetlands
A wetland is a land area that is saturated with water, either permanently or seasonally, such that it takes on the characteristics of a distinct ecosystem. Primarily, the factor that distinguishes wetlands from other land forms or water bodies is the characteristic vegetation that is adapted to its unique soil conditions: Wetlands consist primarily of hydric soil, which supports aquatic plants. The water found in wetlands can be saltwater, freshwater, or brackish.
Main wetland types include swamps, marshes, bogs and fens.
1. A swamp is a wetland that is forested. Many swamps occur along large rivers where they are critically dependent upon natural water level fluctuations.
2. A marsh is a wetland that is dominated by herbaceous rather than woody plant species. Marshes can often be found at the edges of lakes and streams, where they form a transition between the aquatic and terrestrial ecosystems.
3. A bog is characterized by spongy peat deposits and a floor covered by sphagnum mosses.
4. Fens are usually fed by mineral-rich surface water or groundwater, and not from precipitation.
Sub-types include mangrove, carr, pocosin, and varzea. Wetlands play a number of roles in the environment, principally water purification, flood control, and shoreline stability. Wetlands are also considered the most biologically diverse of all ecosystems, serving as home to a wide range of plant and animal life.
Wetlands occur naturally on every continent except Antarctica. They can also be constructed artificially as a water management tool, which may play a role in the developing field of water-sensitive urban design. The largest wetlands in the world include the Amazon River basin and the West Siberian Plain.
A patch of land that develops pools of water after a rain storm would not be considered a "wetland," even though the land is wet. Wetlands have unique characteristics: they are generally distinguished from other water bodies or landforms based on their water level and on the types of plants that thrive within them. Specifically, wetlands are characterized as having a water table that stands at or near the land surface for a long enough period each year to support aquatic plants. A more concise definition is a community composed of hydric soil and hydrophytes. Wetlands have also been described as ecotones, providing a transition between dry land and water bodies
Ecology/Characteristics
The most important factor producing wetlands is flooding. The duration of flooding determines whether the resulting wetland has aquatic, marsh or swamp vegetation. Other important factors include fertility, natural disturbance, competition, herbivory, burial and salinity. When peat accumulates, bogs and swamps arise.
Wetlands vary widely due to local and regional differences in topography, hydrology, vegetation, and other factors, including human involvement. Wetlands can be divided into two main classes: tidal and non-tidal areas.
Wetland hydrology is associated with the spatial and temporal dispersion, flow, and physiochemical attributes of surface and ground water in its reservoirs. Based on hydrology, wetlands can be categorized as riverine (associated with streams), lacustrine (associated with lakes and reservoirs), and palustrine (isolated). Sources of hydrological flows into wetlands are predominately precipitation, surface water, and ground water. Water flows out of wetlands by evapotranspiration, surface runoff, and sub-surface water outflow. Hydrodynamics (the movement of water through and from a wetland) affects hydroperiods (temporal fluctuations in water levels) by controlling the water balance and water storage within a wetland. Landscape characteristics control wetland hydrology and hydrochemistry. The O2 and CO2 concentrations of water depend on temperature and atmospheric pressure. Hydrochemistry within wetlands is determined by the pH, salinity, nutrients, conductivity, soil composition, hardness, and the sources of water. Water chemistry of wetlands varies across landscapes and climatic regions. Wetlands are generally minerotrophic with the exception of bogs. Bogs receive their water from the atmosphere and therefore their water has low mineral ionic composition because ground water has a higher concentration of dissolved nutrients and minerals in comparison to precipitation.
What about wetlands soil? Carbon is the major nutrient cycled within wetlands. Most nutrients, such as sulfur, phosphorus, carbon, and nitrogen are found within the soil of wetlands. Anaerobic and aerobic respiration in the soil influences the nutrient cycling of carbon, hydrogen, oxygen, and nitrogen, and the solubility of phosphorus thus contributing to the chemical variations in its water. Wetlands with low pH and saline conductivity may reflect the presence of acid sulfates and wetlands with average salinity levels can be heavily influenced by calcium or magnesium. Biogeochemical processes in wetlands are determined by soils with low redox potential.
Major wetland types for flood control: floodplain Storage Reservoirs and Flood Protection. The wetland system of floodplains is formed from major rivers downstream from their headwaters. The floodplains of major rivers act as natural storage reservoirs, enabling excess water to spread out over a wide area, which reduces its depth and speed. Wetlands close to the headwaters of streams and rivers can slow down rainwater runoff and spring snowmelt so that it doesn’t run straight off the land into water courses. This can help prevent sudden, damaging floods downstream. Groundwater replenishment Major wetland type: marsh, swamp, & subterranean karst and cave hydrological systems. The surface water which is the water visibly seen in wetland systems only represents a portion of the overall water cycle which also includes atmospheric water and groundwater.
Wetland systems are directly linked to groundwater and a crucial regulator of both the quantity and quality of water found below the ground. Wetland systems that are made of permeable sediments like limestone or occur in areas with highly variable and fluctuating water tables especially have a role in groundwater replenishment or water recharge. Sediments that are porous allow water to filter down through the soil and overlying rock into aquifers which are the source of 95% of the world’s drinking water.
Water purification is also an important job of wetlands. Many wetland systems possess biofilters, hydrophytes, and organisms that in addition to nutrient up-take abilities have the capacity to remove toxic substances that have come from pesticides, industrial discharges, and mining activities. The up-take occurs through most parts of the plant including the stems, roots, and leaves . Floating plants can absorb and filter heavy metals. Eichhornia crassipes (water hyacinth), Lemna (duckweed) and Azolla (water fern) store iron and copper commonly found in wastewater. Many fast-growing plants rooted in the soils of wetlands such as Typha (cattail) and Phragmites (reed) also aid in the role of heavy metal up-take. Animals such as the oyster can filter more than 200 liters (53 gallons) of water per day while grazing for food, removing nutrients, suspended sediments, and chemical contaminants in the process.
Capacity: The ability of wetland systems to store nutrients and trap sediment is highly efficient and effective but each system has a threshold. An overabundance of nutrient input from fertilizer run-off, sewage effluent, or non-point pollution will cause eutrophication. Upstream erosion from deforestation can overwhelm wetlands making them shrink in size and see dramatic biodiversity loss through excessive sedimentation load. The capacity of wetland vegetation to store heavy metals is affected by waterflow, number of hectares (acres), climate, and type of plant.
Constructed wetlands
The function of most natural wetland systems is not to manage wastewater, however, their high potential for the filtering and the treatment of pollutants has been recognized by environmental engineers that specialize in the area of wastewater treatment. These constructed artificial wetland systems are highly controlled environments that intend to mimic the occurrences of soil, flora, and microorganisms in natural wetlands to aid in treating wastewater effluent. Artificial wetlands provide the ability to experiment with flow regimes, micro-biotic composition, and flora in order to produce the most efficient treatment process. Other advantages are the control of retention times and hydraulic channels.The most important factors of constructed wetlands are the water flow processes combined with plant growth. Constructed wetland systems can be surface flow systems with only free-floating macrophytes, floating-leaved macrophytes, or submerged macrophytes; however, typical free water surface systems are usually constructed with emergent macrophytes. Constructed wetlands can be adapted to treat raw sewage, secondary domestic sludge, enhance water quality of oxidation ponds’ discharge, storm waters, mining waste, and industrial and agricultural waste effluents.
Conservation
Wetlands have historically been the victim of large draining efforts for real estate development, or flooding for use as recreational lakes. Since the 1970s, more focus has been put on preserving wetlands for their natural function yet by 1993 half the world's wetlands had been drained. Wetlands provide a valuable flood control function. Wetlands are very effective at filtering and cleaning water pollution, (often from agricultural runoff from the farms that replaced the wetlands in the first place). To replace these wetland ecosystem services, enormous amounts of money had to be spent on water purification plants, along with the remediation measures for controlling floods: dam and levee construction.
Acre for acre, wetlands are the most productive non-tropical ecosystem. Although small, this wetland in Bluegrass Downs will provide habitat for plants and animals not common to this area as well as provide many other geological jobs to its location.
To qualify for this EarthCache, please send us an email or message via our Geocaching profile with the answers to the following questions. Please include the name of the cache along with your answers. Photos are encouraged!
DO NOT POST THE ANSWERS IN YOUR LOG.
- Based on hydrology, what type of wetland can this be categorized?
- Based on the information on the cache page and your observations, What type of Wetland is this location? (Swamp, Marsh, Bog, or Fen)
- Is this wetland a naturally occuring one, or constructed by man?
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