Trajectories, drivers, and probabilities of land cover change in a disturbed forested watershed in eastern Taiwan

Understanding the trajectories, drivers, and probabilities of land cover change can provide essential information for forested watershed planning and sustainable management. This paper demonstrates that the Taimali watershed in eastern Taiwan underwent a dramatic decrease in forest cover under the influences of frequent earthquakes and typhoons during 2005–2011. To grasp the dynamics of land cover change, this study applied a combined land-change analysis approach using trajectory analysis and logistic regression. The results of trajectory analysis indicate that three change trajectories, covering 75.65 % of the total changed area, were considered the major trends of alterations, including the trajectories of Forest-Landslide, Forest-Channel, and vegetation recovery. Based on the causes of land conversion, most land transformation resulted from natural causes. Therefore, natural forces play a pivotal role in land cover change in the Taimali watershed. The results of logistic regression analysis show that lithology is the most important spatial determinant for occurrence probability of three change trajectories, followed by aspect and slope. Three maps of occurrence probability of the change trajectories were produced using regression coefficients. With the validation of the relative change intensity index, the results reveal that the observed change trajectories considerably coincided with the zones that had higher probabilities of change and covered a small area. Thus, three spatial statistical models are helpful tools for projecting the occurrence probabilities of the change trajectories.