Evaluation of ecological restoration through vegetation patterns in the lower Tarim River, China with MODIS NDVI data Zhandong Sun a , Ni-Bin Chang b, ⁎, Christian Opp c , Thomas Hennig c a State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Science, Nanjing, China b Department of Civil, Environmental, and Construction Engineering, University of Central Florida, Orlando, Florida, USA c Faculty of Geography, University of Marburg, Marburg, Germany abstract article info Article history: Received 7 March 2010 Received in revised form 3 October 2010 Accepted 5 October 2010 Available online 20 October 2010 Keywords: Tarim River Ecosystem restoration Water diversion MODIS Seasonally integrated NDVI Coefficient of Variation (CoV) The lower Tarim River had dried up nearly 30 years before an ecological water diversion project (EWDP) for ecological restoration was implemented in 2000. Since then, eight intermittent water deliveries have been carried out for restoring this seriously degraded riparian ecosystem. To evaluate the efficacy and effectiveness of these operations, the Normalized Difference Vegetation Index (NDVI) data set derived from bands 1 and 2 of the MODerate-resolution Imaging Spectroradiometer (MODIS) on board NASA's Terra satellite was applied to identify the spatial and temporal variations of vegetation cover along the river corridor with about 320 km in length. The goal of this study is thus to generate seasonally integrated NDVI (SINDVI) in growing seasons between April and October so as to investigate a general vegetation patterns as well as examine the inter- annual SINDVI for discerning the status of ecosystem restoration. The spatiotemporal variations of vegetation cover were further characterized based on those inter-annual SINDVI data with the aid of Coefficient of Variation (CoV). Research findings indicate that ecosystem integrity was strengthened after a series of water diversion efforts and groundwater table control in the past few years. As the degree of ecosystem restoration is in progress, continuous operation of water diversion is still necessary in response to the needs for restoration of dense vegetation in the riparian buffer within this arid or semi-arid region. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Vegetation cover is a critical component of terrestrial ecosystems especially in arid and semi-arid regions, which must be sustained by sufficient water (Hadley and Szarek, 1981; Lehouerou, 1984). The vegetation dynamics with respect to space and time is therefore largely dominated by the availability of water (Elmore et al., 2006; Li et al., 2001). The variations of water availability affect the stability of primary productivity, thereby controlling the associated ecological changes and landscape dynamics (Shafroth et al., 2002). When upstream river flows are regulated for multipurpose water resource management, detrimental hydrological and ecological consequences often impact the ecosystem integrity downstream. This has become an increasingly urgent issue in some lower reaches of inland rivers in northwestern provinces of China (Li et al., 2009; Ma et al., 2005; Qi and Luo, 2005). Due to the intensified anthropogenic activities during the most recent 50 years, the lower Tarim River with about 320 km in length had dried up in 1972, which, consequently, led to a serious decline of vegetation cover and drastic changes in plant community structures along the river corridor (Hao et al., 2009). In order to restore the degraded riparian ecosystem, the Chinese Government invested 10.7 billion RMB to launch the contingent plan via an ecological water diversion project (EWDP) in 2000. In this thrust, fresh water was transported from the Bosten Lake to the lower Tarim River for ecosystem restoration. Ground-water level that also affects plant species diversity along the lower Tarim River was monitored too. The primary goal of the EWDP is to restore the riparian vegetation in the lower Tarim River. Since 2000, the efficacy and effectiveness of the EWDP have been widely concerned. Several studies were carried out to investigate the ecohydrological processes with respect to ground-water flows, mineralization, and plant diversity through in- situ monitoring and measurements (Chen et al., 2006; Hou et al., 2007; Tao et al., 2008; Xu et al., 2007). Nevertheless, the holistic information of vegetation dynamics with respect to both space and time across the whole lower Tarim River is still missing. Because natural vegetation cover plays a critical role as the major producer of organic matter, the status of ecosystem recovery can largely affect the ultimate environmental conditions in this region. Satellite remote sensing is a useful tool to analyze the vegetation dynamics over space and time (Ringrose and Matheson, 1991). Vegetation indices have been developed to qualitatively and quantitively assess vegetation covers using spectral measurements (Bannari et al., 1995). The first earth resources satellite, a.k.a. Landsat- Ecological Informatics 6 (2011) 156–163 ⁎ Corresponding author. Tel.: + 1 407 8231375. E-mail addresses: sun@niglas.ac.cn (Z. Sun), nchang@mail.ucf.edu (N.-B. Chang), opp@staff.uni-marburg.de (C. Opp). 1574-9541/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.ecoinf.2010.10.002 Contents lists available at ScienceDirect Ecological Informatics journal homepage: www.elsevier.com/locate/ecolinf