tailieunhanh - LANDSCAPE ECOLOGY in AGROECOSYSTEMS MANAGEMENT - CHAPTER 4

Do các liên kết hydro mạnh bất thường giữa các phân tử nước, là một trong những chất tuyệt vời nhất trong tự nhiên. Nhiều người trong số thuộc tính của nó là chất lượng khác với các chất khác tham gia trong các quá trình quan trọng cho chức năng sinh quyển - ví dụ, nước có nhiệt độ cao bất thường nóng chảy và nhiệt độ sôi, một trong nhiệt cụ thể cao nhất và nhiệt ẩn của bốc hơi, hằng số điện môi cao nhất, và rất cao lực lưỡng cực. Bằng cách xác định các quá trình chuyển đổi năng lượng mặt. | CHAPTER 4 Water Balance in Agricultural Landscape and Options for Its Management by Change in Plant Cover Structure of Landscape Andrzej Kedziora and Janusz Olejnik CONTENTS Introduction General Water Balance Water Balance of Agricultural Landscape Structure of Water Balance Precipitation Evapotranspiration Runoff Factors Determining Water Balance General Weather and Climatic Conditions Soil Conditions Plant Cover and Land Use Water Management in the Landscape Water Deficit in the Landscape Improving Water Retention Controlling Water Balance by Plant Cover Structure Impact of Climate Change on Water Balance References 2002 by CRC Press LLC INTRODUCTION Owing to unusually strong hydrogen bonds between molecules water is one of the most amazing substances in nature. Many of its properties are qualitatively different from those of other substances participating in processes important for biosphere functioning for example water has anomalous high temperature at melting and boiling points one of the highest specific heat and latent heat of evaporation the highest dielectric constant and very high dipole momentum. By determining the process of solar energy transformation into organic matter and thereby the conditions of plant growth and development water determines the level of agricultural production. Thanks to its enormous thermal properties water controls the thermal status of plants and allows the plant body to store a large amount of thermal energy which buffers the plant against rapid changes in environmental temperature. Continuous sufficient flux of water flowing through the soil-plant-atmosphere system is indispensable for utilizing the potential for the ecosystem to achieve plant growth and high yields. Three scales of water cycle can be distinguished Figure Global hydrologic cycle Figure which consists of water exchanged between oceans and continents through atmospheric circulation and river water flow Local hydrologic cycle Figure marked by a .