Introduction

Wetlands are a critical feature of the global landscape because of their unique role in regulating global biogeochemical cycles. The value and function of wetlands are well recognized, as evidenced by national and international policies to preserve wetland ecosystems. Wetlands are some of the most biologically productive ecosystems on earth; their productivity can exceed that of terrestrial and aquatic systems. Wetlands not only serve to promote and sustain biota in many forms, but also serve as living lters that process pollutants from terrestrial runoff and atmospheric deposition. Biodegradation of organic compounds, elemental cycling, atmospheric exchange, processing capacity, and plant response are controlled by the unique conditions found in the wetland environment (Figure 1.1).