tailieunhanh - WETLAND PLANTS: BIOLOGY AND ECOLOGY - CHAPTER 3

Môi trường vật lý thực vật đất ngập nước I. Giới thiệu về môi trường đất ngập nước Nước là một trong những yếu tố chính mà tổ chức cảnh quan, làm như vậy thông qua các quá trình như vận chuyển, xói mòn, giải pháp, lọc, và thoát hơi nước (Brown 1985). Các chế độ thủy văn của vùng đất ngập nước là một trong các biến số chính để xác định thành phần, phân phối, và sự đa dạng của thực vật đất ngập nước. Điều kiện thủy văn ảnh hưởng đến thành phần loài, các xu hướng successional, năng. | 3 The Physical Environment of Wetland Plants I. An Introduction to the Wetland Environment Water is one of the primary factors that organizes the landscape doing so through processes such as transport erosion leaching solution and evapotranspiration Brown 1985 . The hydrologic regime of a wetland is one of the key variables that determine the composition distribution and diversity of wetland plants. Hydrologic conditions affect species composition successional trends primary productivity and organic matter accumulation Gosselink and Turner 1978 Brinson et al. 1981 Howard-Williams 1985 van der Valk 1987 . Factors related to the hydrologic regime that affect wetland plant communities include water depth Spence 1982 Grace and Wetzel 1982 1998 water chemistry Ewel 1984 Pip 1984 Rey Benayas et al. 1990 Rey Benayas and Scheiner 1993 and flow rates Westlake 1967 Lugo et al. 1988 Nilsson 1987 Carr et al. 1997 . Hydrology also influences the plant community composition and primary productivity by influencing the availability of nutrients Neill 1990 soil characteristics Barko and Smart 1978 1983 and the deposition of sediments Barko and Smart 1979 . The hydrologic regime can be thought of as a master variable with respect to all these factors since it not only determines the hydroperiod but it is also instrumental in carrying nutrients and sediment and so modifying soil type into a wetland. In this chapter we focus on the ways in which hydrology controls plant community structure. We describe the hydrologic budget with an emphasis on transpiration and its measurement. We also discuss how hydrologic forces affect species distribution community composition and primary productivity. Following the section on hydrology we discuss the characteristics of saturated soils that render them inhospitable to plants. Low oxygen levels stress plant roots which require oxygen to maintain cellular respiration. High concentrations of toxic forms of metals accumulate and nutrients may become .