生态输水前后台特玛湖植物多样性变化特征

Change of Plant Diversity in the Taitema Lake Area before and after Implementing the Ecological Water Conveyance

通过综合分析台特玛湖2000-2017年连续的植被数据资料,对每个监测断面的漫溢样地和无漫溢样地(即对照样地)的植被变化开展野外调查和数据采集工作。研究发现:①随着生态输水的进行,台特玛湖植被的生态效益逐渐显现,生物多样性明显增加。在漫溢区,单位面积物种数、植被盖度和植被密度的平均值分别为6.8种·(100m^2)^-1、30%和1 350个·(100m^2)^-1,较地下水抬升区分别增加了3倍、3.29倍和49倍;并且输水前(2000年)湖区植物有2科3属7种,输水后增至10科21属26种,增加了8科18属19种。②近十几年生态输水过程中,台特玛湖植被向以芦苇(Phragmites australis)为主的盐渍化低地草甸方向发展,趋于简单化。演变特征主要为:输水初期(2000-2005年)地表植被以新萌发的一年生草本占主要优势(重要值0.50),其次是多年生草本(重要值0.20),最后是灌木(重要值0.10);随输水的进行,2009年一年生草本植物减少,进而被灌木与多年生草本替代:灌木为盐穗木(Halostachys caspica)、盐节木(Halocnemum strobilaceum)等原生盐生植物,且出现新萌发的幼苗,多年生草本为芦苇;2012-2016年,在输水之后充沛的水资源环境下,优势种组成趋于简单,植被向以芦苇为主的盐渍化低地草甸方向发展。

It is of great significance for regenerating the ecological environment in the lower reaches of the Tarim River to study the change of plant diversity in the Taitema Lake area before and after implementing the ecological water conveyance.Through the comprehensive research on the continuous data of vegetation in the Taitema Lake area during the preiod of 2000-2017,in this study the field investigation and data collection were carried,and the difference in vegetation variation between the overflow plots and the non-flood plots(i.e.the controlled plots)was compared.The results were as follows:①With implementing the ecological water conveyance,the ecological benefits of the vegetation in the Taitema Lake area have gradually emerged,and the biodiversity has been increased significantly.In the flooded area,the average number of plant species per unit area,vegetation coverage and vegetation density were 6.8 number·(100 m^2)^-1,30%and 1 350 number·(100 m^2)^-1,and they were increased by 3,3.29 and 49 times of those in the regions where the groundwater level was risen only.Before implementing the ecological water conveyance,there were 7 plant species in 3 genera and 2 families in the lake area.After that they were increased to 26 species in 21 genera and 10 families;②After implementing the ecological water conveyance for 10 years,the vegetation in the Taitema Lake area was developed towards the salinized lowland meadow dominated by reeds and tended to be simplified.The vegetation evolution was characterized by that the newly germinating vegetation was dominated by annual herbs with an important value of 0.50 at the early stage of the ecological water conveyance(2000-2006),followed by perennial herbs with an important value of 0.20 and by shrubs with an important value of 0.10.With the continuous ecological water conveyance,the annual herbs decreased in 2009 and was gradually replaced by shrubs and perennial herbs.The shrubs were the native halophytes including Halostachys caspica and Halocnemum strobilaceum,and some newly germinated seedlings appeared.Under the environment with abundant water resources during the period from 2012 to 2016,the dominant species composition tended to be simple,and the vegetation developed towards the salinized lowland meadow dominated by reeds.