tailieunhanh - WETLAND PLANTS: BIOLOGY AND ECOLOGY - CHAPTER 6

Năng suất Tiểu học thực vật đất ngập nước I. Giới thiệu Sản xuất chính của vùng đất ngập nước nhiều là khá cao, đặc biệt là khi so sánh với các cộng đồng tự nhiên khác hoặc thậm chí để quản lý đất canh tác nông nghiệp cao (Bảng ). Một giá trị cao cho năng suất trên mặt đất chính của vùng đầm lầy và đầm lầy trong vùng ôn đới là khoảng 3500 gam trọng lượng khô trên một mét vuông mỗi năm (g m-2 năm-1). Trong các vùng đất ngập nước lạnh và than bùn đầm lầy một. | Part III Wetland Plant Communities Function Dynamics Disturbance 2001 by CRC Press LLC 6 The Primary Productivity of Wetland Plants I. Introduction The primary productivity of many wetlands is quite high especially when compared to other natural communities or even to highly managed agricultural croplands Table . A high value for the aboveground primary productivity of swamps and marshes in temperate zones is about 3500 grams dry weight per square meter per year g m-2 yr-1 . In cold wetlands and peat bogs an upper limit of about 1000 g m-2 yr-1 is typical Bradbury and Grace 1993 . Wetlands with emergent herbaceous vegetation are often more productive than other wetland types although high values are found in some mangrove swamps as well Table . Wetland primary productivity depends upon the type of wetland and the vegetation found there as well as on hydrology climate and environmental variables such as soil type and nutrient availability. Wetlands that receive nutrient subsidies either naturally from flooding or from farm runoff tend to be more productive than those that receive nutrients only from rainwater such as scrub cypress swamps or ombrotrophic bogs Brown 1981 . In a highly productive freshwater marsh in Wisconsin from 2800 to 3800 g m-2 yr-1 the soil nutrients were found in higher concentrations than in upland soils and in excess of what is needed for agricultural crops Klopatek and Stearns 1978 . Still water wetlands such as bogs or scrub cypress swamps have low primary productivity 100 to 300 g m-2 yr-1 but they may perform essential ecological functions by supporting wildlife or rare plant species or they may be sites of important storages of water or peat Brown 1981 . The salt marshes of the arctic and subarctic are among the least productive of coastal wetlands. Nonetheless they are valuable as vital staging areas for large populations of migrating waterfowl Roberts and Robertson 1986 . A. Definition of Terms The terms used to report primary .