Temporal-spatial Changes Of Water Resource And Ecological Safety Assessment In Artificial Forest Of Carbon Dioxide Capture

Xinjiang is an important arid zone in northwest of china where vegetation growth status is closely related to the distribution of water resources. So, it is important to study temporal-spatial changes of water resource in arid zone to its eco-system. Ecological safety is an important component of national safety. Karamay is an artificial oasis where natural ecological environment is altered by human activities such as diversion works, vegetation construction and so on. This kind of ecological environment is very fragile. Therefore, it is particularly important to research the safety of various eco-systems in this area.The data of soil, vegetation and groundwater in Artificial Forest of Carbon Dioxide Capture (AFCDC) in Karamay was obtained depending on investigation and sampling. The temporal-spatial changes of soil moisture and groundwater and its relations with vegetation growth were studied based on these data.Further, an index system was built to assess the ecological safety of AFCDC. The results can be concluded as follows.Firstly, soil moisture is a main limiting factor to vegetation in AFCDC. Under the influence of factors such as terrain, physiognomy, and type of vegetation, there were certain spatial changes of soil moisture in different geographical points, even in different depth of soil in the same point. The soil moisture content is comparatively higher in 0～40cm depth, lowest in 40～60cm depth, and media in 60～100 cm depth. Although the soil moisture in different soil depth showed different distributing charateristics, there was a similarity that it was lowest in the south of AFCDC near the desert area. The main factors affected were soil texture and vegetation type. There was obvious advantage in maintaining soil moisture for P. Russkii Jabi., comparing with other types of vegetation such as Fraxinus chinensis Roxb and Elaeagnus angustifolia L.. Secondly, ground water depth had reduced from 11.39m in 2005 to 3.64m in 2010. Meanwhile, from west towards east in AFCDC, ground water depth had a deeper trend. Moreover, from 2005 to 2009, groundwater mineralization has reduced from 18.925g/L to 14.239g/L. The temporal-spatial changes of water-soluble salt of groundwater were obvious.Thirdly, the average of assessment results of AFCDC ecological safety was 3.004. About 60% of the area was unsafe, and the rest was in a general level.So, the ecological safety in AFCDC was not good. The indexes of NDVI, growing status of vegetation, desertification, economic output and ecosystem services value among all the twelve indexes highly impacted the assessment results.