夏延縣 的英文怎麼說

The structures and dynamic changes of the artifical sand - fixing vegetation were studied based on the follow views : components of vegetation community, plant diversity, life - forms of vegetation, trends of plant growth, characteristics of the vertical and horizontal structure of vegetation, relationship between the vegetation community and environment ( including soil moisture temperature etc. ), relationship between the vegetation community and characteristics of plant physiological activities. some results were showed as follow : 1. components, diversity and life style of artificial vegetation in shapotou region the marked changes of artificial vegetation have taken place during more than 40 years, since the establishment of sand - fixing vegetation

本文以騰格里沙漠東南緣寧夏中衛縣沙坡頭地區人工固沙植被作為研究對象，採用傳統生態學的野外調查方法，從植被群落的組成、多樣性、生活型、群落生長動態、垂直結構特徵、水平結構特徵、群落結構與周圍環境（土壤含水量、溫度）相互關系及其與植物自身生理生態適應特徵關系等多個角度研究了人工植被群落的結構及其動態變化，取得了如下研究結果： 1 、植被群落組成、多樣性及生活型：沙坡頭地區人工植被經過近50年的演變，從流動沙丘到固定沙地，沙地植被的動態變化經歷了從人工植被到人工?自然植被的轉變，從人工植被建立初期的少數幾種引種植物到現有30多種植物，隨著固定沙地時間的延長，植物種類日趨豐富，並且人工植被在15 25年、 40 50年兩個階段，物種的周轉速率最大，即群落結構變化最大。