User:Tivinjd/sandbox

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Contents

 * 1Soil[edit]
 * 2Hydrology[edit]
 * 2.1Precipitation
 * 2.2Evapotranspiration
 * 3Differences Between Marshes and Swamps
 * 4Human Impacts

Soil
Soils contain organic matter, air, water and mineral matter. The soil has very slow decomposition rates and is often black or brown. The soils in wetlands are often hydric in nature, which means they are completely saturated and have no oxygen. The soils of marshes and wetlands play an important role as carbon sinks. Carbon sinks are formed in these marshes through the slow decomposition of organic matter that arises from anaerobic conditions due to flooding. The lack of oxygen in the soil prevents bacteria and fungi from breaking down organic matter, leading to large deposits of Carbon.

Hydrology
Freshwater marshes are dynamic ecosystems. Aspects of the water like depth, velocity, oxygen concentration, and temperature change frequently. Marshes can be classified based on their hydrology. Marshes can be flooded permanently, intermittently, temporarily, seasonally, and semi-permanently. Groundwater reserves, surface runoff, and precipitation are the three main sources of water in marshes. Marshes are commonly found in areas of topography that have depressions. The depressions in the land aid in the ability for marshes to be able to collect and hold water. Geographic locations of marshes coincide with depressions formed by glacial movement, water movement and tectonic activities. The hydrologic processes of marshes vary based on location due to changes in precipitation, evapotranspiration, groundwater inflow and runoff.

Precipitation
Water reaches marshes directly through precipitation or indirectly by watershed runoff. Both of these ways that water reaches the marches influences surface water or ground water flow and plays a role in wetland hydrology. There is a positive correlation between high annual precipitation in the form of rain, snow, or mist and wetland/marsh presence. Snow has the ability to melt and recharge groundwater in temperate marshes where four seasons occur annually.

Evapotranspiration
The combination of atmospheric evaporation and plant transpiration is defined as Evapotranspiration. This is the total amount of water that leaves the surface of a landscape and is put back into the atmosphere as water vapor. Seasonal evapotranspiration can be highly variable due to changes in solar radiation, humidity, and moisture in the soil, and plant type/density. The position of the water table can play a role in how much moisture is evaporated. Water tables that are closer to the surface of the marsh have a higher chance of losing more water than marshes with lower water tables.

Differences Between Marshes and Swamps
Marshes and swamps are two types of vegetated wetlands that are primarily found near bodies of water and are comprised of mineral rich, hydric soil. One main difference between marshes and swamps are their respective types of vegetation. Swamps are characterized by the presence of woody plants, such as Tupelo and Cypress trees, and saturated soils with standing water throughout some of the year. Marsh vegetation is primarily soft-stem vegetation and herbaceous plants and experience frequent or continual flooding from near bodies of water.

Human Impacts
Freshwater wetlands are subjected to a myriad of human impacts that affect the ecosystem services. The change in flow regime of a marsh's primary water source can deplete the size of the marsh, therefore limiting habitat for organisms. The most destructive process for wetlands is that humans redirect water sources and drain marshes to provide land for development and agriculture. According to the USGS, approximately 20 states have a 50% decrease of their original marshes and wetlands, while another 7 states have decreased over 80% of marsh/wetland territory. Excess runoff from city sewage or agriculture can overload marshes with nutrients causing harmful phytoplankton blooms. An increase in phytoplankton and other organic matter can lead to the deoxygenation of marshes which results in lower water qualities and a loss of biodiversity. Despite the negative impacts humans have inflicted on wetland habitat, many government and nongovernment organizations are working to reestablish wetlands across the United States. The enhancement of destroyed wetlands aids in promoting water quality, flood attenuation and recreational opportunities.