拉鲁湿地生态环境及动植物物种资源变化特征研究

2001～2002年对拉鲁湿地近50年(1951～2000年)生态环境和动植物资源变化特征的研究结果表明:受近50年拉萨城市发展、资源开采等人类活动的影响,拉鲁湿地的面积、水环境、植物种类、植物群落和动物物种均较20世纪50年代初期(早期)发生了较为显著的变化。其主要变化特征为:①湿地面积由早期的12km²锐减为6.2km²;②湿地由终年积水演变成季节性积水,水位梯度也由早期的0.3～0.8m增大为0～1.5m;③湿地植物物种在数量上较早期增加了13科31属32种,但原生的湿生植物物种却有所下降;④湿地植物群落已由早期芦苇和苔草群落占绝对优势的状况演变为多种植物群落共生的格局;⑤湿地鸟类和鱼类的种类及数量变化显著,目前湿地中鸟类常见物种仅剩5种,鱼类仅剩鲫鱼和鲤鱼2种,且均为人工放养的外来鱼种。

Research on the Variation Characteristics of Eco-environment and Propagation Resources in Lalu Wetland

During the period of 2001-2002,the variation characteristics of eco-environment and propagation resources in the last fifty years in Lalu wetland were investigated.The results showedthat influenced by human activities such as urban development,resources exploitation,agricultural production and stockbreeding,the area,water environment,plant species and communities,animal species of Lalu wetland had changed remarkably with time,differing from those in the early 1950s.The major characteristics are as follows:1) the area of wetland had been reduced from 12km² to 6.2km²; 2) in the early times the wetland was inundated by water all the year round,but now only partial area was inundated by water with gradient of water level increased from 0.3～0.8m to 0～1.5m;3)compared with the number of plant species in the early times,32 species belonging to 31 genera and 13 families were increased in wetland,but some species of helophyte plant were reduced;4)in the early times,phragmites australis and carex communities were in domination,however,the horizontal structure of the communities in wetland today showed multiple communities intergrowth;and 5) compared with the early times,the bird number and fish species changed remarkably.Today,the bird species which can be seen frequently in wetland only totals five,the Carassius and Cyprinus carpio which didn't exist in the early times have become the only fish species in the wetland.