Wetlands are areas of land that are covered with fresh water or saltwater and feature species adapted to life in a saturated environment. The shallow water allows the growth of rooted or anchored plants such as water lilies but also free floating plants like duckweed.
Wetlands represent the meeting of two habitats (land and water) and are therefore some of the most biodiverse areas in the world (some say more than rainforests) with many land and water species, and some that are unique only to the wetlands.
Wetlands begin with the saturation of a land habitat. Many were formed at the end of the last ice age when glaciers retreated and the shallow depressions left over filled with water. Over time, sediment and organic debris collected in the depressions and the water became shallower until the accumulated sediment and debris filled in the water and left behind shallow wetland ponds surrounded by dry land.
Wetlands can also form when a river overflows its banks or when changes in sea level make once dry areas saturated. Additionally, climate can impact wetland formation, for example high rainfall in normally dry areas with poor drainage causes the ground to become saturated.
Once wetlands form, they are constantly changing. Just as growing sediment and debris levels cause the wetlands to form, roots and dead plant matter can cause the wetland to become more shallow, eventually to the point where the upper layers rise above the water table and dry out. When this happens, terrestrial plant and animal species can colonize the area.
Many wetlands are along rivers and streams (these are sometimes called riparian wetlands), in isolated depressions, along the edges of lakes and ponds, or in other low-lying areas where the groundwater meets the soil's surface or when runoff is significant enough to allow formation. Precipitation can also sometimes saturate the soil and create bogs or temporary wetlands called vernal pools.
In addition to being unique ecosystems supporting a broad range of inhabitants, wetlands also act as a filter for pollution and excess sediment. This is important because rainwater runoff can be laden with dangerous pesticides and other pollutants, especially in an urban area such as this. Wetlands also aid in flood protection as they act as sponges that absorb rain and floodwater.
To log this cache, email the cache owner with the following:
- What signs do you see of the fluctuation in water levels in this wetland?
- Given your observations, what is your estimate of the current water level compared to the highest previous level you determine?