Measuring cumulative effects in a fragmented landscape

Scientists recognize the importance of studying cumulative environmental effects as stressors, as there are countless stressors in human and technological development. However, existing studies acknowledge methodological limitations of measuring effects that combine and accumulate over time, making it difficult to interpret the processes leading to a given current landscape. Therefore, the objective of this study was to develop a method that would make it possible to define the sequence of human actions and to measure relationships between type, intensity and distribution of cumulative effects by analyzing the past and present composition of the landscape. The method is based on the identification of the cumulative value of effects in landscape units of 900 m(2). The chronosequence of human activities triggering accumulated effects was obtained from superimposed maps and the magnitude of effects was evaluated using area graphs. The method proposed was applied in a study area, resulting in a map that clearly showed the distribution and synergy of cumulative effects in the study area. (C) 2012 Elsevier B.V. All rights reserved.