This bad reputation and the realization that wetlands, when drained, often converted to very productive and valuable farm land were the root causes of wetland acreage losses which began in earnest in the mid-1800s. Wetlands share some of the characteristics of both uplands and open water. Because wetlands are often located in an intermediate position between uplands and open water, many people call them transitional areas. Despite the early belief that wetlands were more valuable if converted to another use, time has proven that wetlands serve many functions which make them valuable in their natural state. The hydrology of a wetland also drives the formation of hydric soils.
Anaerobic conditions develop when water displaces oxygen present within the pore spaces of a soil.
Hydric soils are often gray in color and may smell like rotten eggs. Orange-colored deposits often occur around roots growing within hydric soils. Plants that are able to grow and reproduce in wetlands do so because of special adaptations which allow them to survive in a waterlogged environment. Many wetland plants have very spongy roots. These roots have air spaces, which are believed to allow the movement of oxygen from the leaves to the roots, thereby allowing the plant to thrive despite the anaerobic conditions present in the soil.