Abstract: Karst rocky desertification is the third severe land degradation in China, following desertification in the north and soil and water loss in the Loess Plateau. This paper reviewed the progress and problems in the studies of Karst rocky desertification, and proposed a new method, which is temporal trajectory analysis based on high-resolution remote sensing data. At present, we have achieved great progress in the fields such as karst geology and geomorphology, restoration and reconstruction of Karst ecosystem, spatial pattern and dynamic changes of rocky desertification, evolution mechanism of karst rocky desertification as well as monitoring methods based on remote sensing. However, there are still a number of problemsin the studies of evolutional process of karst rocky desertification: (1) Current studies are mainly focusing on the spatial pattern of the rocky desertification based on remote sensing data and have successfully described the degree of severity of land degradation, but few of them are concerning the evolutional process of karst rocky desertification; (2) Most of the studies on the evolutional mechanism of Karst rocky desertification are qualitative descriptions and few of them are quantitative analyses; (3) The remote sensing monitoring methods normally are the double temporal variation detection method based on the "two time cycle" scales; only the information of "change/no change" or "what changes from what" can be acquired. Therefore, a new method, temporal trajectory analysis based on middle/high resolution remote sensing data, is introduced in this paper. This methodfocuses on "continuous" variations in a long time scale, and it is concerning not only what has changed between two time points, but also "where" and "how" the changes happened. By the temporal trajectory analysis method, the rocky desertification process in a long time series can be investigated, and the development of rocky desertification can be quantitatively and spatiallytracked, so that we can know where, how and why the rocky desertification has happened. Temporal trajectory analysis method has advantages in discovering the evolutional process of rocky desertification. Moreover, quantitative analysis ofthe pattern, process and evolutional mechanism of Karst rocky desertification will be the trend in the future.

Key words: dynamic change, Karst, remote sensing, rocky desertification, Southwest China, temporal trajectory analysis