5. Discussions
5.1. Ecological restoration goals
The obstacles to determining success are closely tied to the problems in setting goals [42]. Reference information can be used to guide ecological restoration [20-22]. Success itself is an imprecise term that means different things in different situation and to different people [42]. We can gain the reference information from the historical states of the study ecosystem or the other existing similar ecosystem that is unaltered [22, 43]. Even two ecosystems look like
the same one, part of the characteristics of them are different. The restoration goals must be realistic and compatible with constraints of the present and projected use of the project site and the surrounding area [42]. The goal of the restoration should be to improve the current condition, rather than match it. In the paper, the restoration goals were set based on the cluster analysis of the historical data, which was more objective and reasonable. The states of
excellent and fine were selected as the high and low restoration goals, respectively. The different restoration levels provide more flexible selections of remedial measures and benefit the decision-making. Schneiders et al. reported a viewpoint that the ecological restoration goals for different groups were linked to different quality requirement [21]. Sometimes, the quality requirements may partly reflect the local desire, partly reflect the manager’s intents, and partly reflect the actual requirements of the lake itself. Other previous studies also indicate the view [6]. The method to select restoration goals in the paper not only reduce the subjectivity but also considered the ecosystem sustainability and integrity.