Cropping Mulberry (Morus alba) in the Drawdown Zone of the Three Gorges Reservoir Yun Liu 1* , J.H. Martin Willison 2 1 Key Laboratory of the Three Gorges Reservoir Region’s Eco-Environment (Southwest University), Ministry of Education, College of Resources and Environment, Southwest University, Chongqing 400716, China 2 School for Resource and Environmental Studies, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4R2 Email: utrecht@swu.edu.cn Abstract. The drawdown zone of China's Three Gorges Reservoir is available for crops during summer, but few perennial crops tolerate the winter flooding stress. We examined white mulberry (Morus alba L.) at a site in Muhe Village, Chongqing, where a 15-yearold mulberry plantation has survived seven cycles of winter immersion since 2009. The plantation lies on riverside terraces and is maintained by silk farmers who have adapted their crop management regime for the changed conditions. Despite benefits to farmers, their use of the resource conflicts with the management regime for the reservoir, which had not anticipated mulberry survival. It is concluded that mulberry trees have potential roles in a strategy for managing the drawdown zone so as to provide environmental protection, ecosystem services and use of the land resource. It is recommended that the reservoir management system become more adaptive and participatory, and that land-use regulations encourage mulberry use. Keywords: Sericulture, Morus alba, Three Gorges Reservoir, flooding stress, ecosystem services 1 Introduction Perennial vegetation provides many environmental benefits on the banks surrounding reservoirs, such as reduced input of sediments, sequestration of soluble nutrients, and shade [1]. In densely-populated developing countries there is also strong demand that environmental benefits be matched with agricultural benefits [2]. While it is relatively easy to obtain both environmental and agricultural benefits above the high water line on the banks of a reservoir, it is difficult in the zone subjected to periodic flooding. Here we describe a white mulberry (Morus alba L.) plantation that grows in the drawdown zone of the Three Gorges Reservoir (TGR) in China and provides valuable harvests for some small-scale farmers who live beside the reservoir. This unusual case is unfolding instructively in a situation that is ecologically and socially complex. China's Three Gorges Dam on the Changjiang (Yangtze River) provides the benefits of flood control, electrical power generation, and ease of river transportation, but with environmental, social and economic costs [3], [4], [5]. Much attention has been paid to the environmental risks and associated mitigations related to the TGR [3], [4], [6], and recently there has been growing interest in restoring ecosystem functions and services to its riparian zone [7], [8], [9], [10], [11]. The Changjiang basin is subjected to heavy summer monsoon rains which have historically produced severe floods in the lower reaches of the river [4], [6]. To overcome this problem, the water level in the TGR is lowered during summer to 30 m below its optimal level for electrical power generation in preparation for flood control (Fig. 1). When a flood pulse arrives, it is attenuated by short-term storage of water in the reservoir and the stored water is subsequently released at a controlled rate calculated to avoid catastrophic damage downstream. Lowering the water in this way during summer creates a reservoir drawdown zone of about 350 km 2 around the edge of the reservoir [6], [12]. The reservoir itself lies within a mountainous region and is confined to the steep-sided valleys of the main river and its many tributaries, and so the drawdown zone consists of a ribbon of sloping land which averages about 70 m in breadth and 4900 km in total ribbon length [8]. Based on surveys and experiments, Yang et al. [10] recently recommended 6 tree species as suitable for restoration of riparian woodland in the upper 170-175m component of the TGR drawdown zone, of Environmental Pollution and Protection, Vol. 1, No. 2, December 2016 https://dx.doi.org/10.22606/epp.2016.12003 81 Copyright © 2016 Isaac Scientific Publishing EPP