Intensity analysis to unify measurements of size and stationarity of land changes by interval, category, and transition

This article presents a quantitative method to analyze maps of land categories from several points in time for a single site by considering cross-tabulation matrices, where one matrix summarizes the change in each time interval. There are three levels of analysis, starting from general to more detailed levels, where each level exposes different types of information given the previous level of analysis. First, the interval level examines how the size and speed of change vary across time intervals. Second, the category level examines how the size and intensity of gross losses and gross gains in each category vary across categories for each time interval. Third, the transition level examines how the size and intensity of a category's transitions vary across the other categories that are available for that transition. At each level, the method tests for stationarity of patterns across time intervals. The unique contribution of this article is that it combines all three levels of analysis into one unified framework that we call intensity analysis, where the more detailed levels are conditional on the less detailed levels. The illustrative case study is for seven categories at the Plum Island Ecosystems site in northeastern Massachusetts, USA, where the largest transition is from Forest to Built during 1985, 1991, and 1999. We compare our approach to other established methods such as the Markov approach in order to show how our proposed intensity analysis gives more information concerning five possible reasons to explain why the transitions vary across time and space.

► Our unified approach develops insights concerning patterns of land change.
► The method relates size, intensity and stationarity of land change at three levels.
► The analysis answers questions concerning five possible explanations of land change.
► Our approach gives more information than other methods such as the Markov approach.
► A computer program to perform the analysis is available from the https://sites.google.com/site/intensityanalysis.