Given those three key assumptions, we can calculate an Index of Species Disturbance<\/strong> (ISD) at the municipal level <\/strong>by overlapping a map of deforestation at very high resolution (1) with a map of Species Richness (2).<\/p>\n

The basic idea behind the ISD indicator is illustrated conceptually in Figure 1 below, which provides a couple of numerical examples to illustrate how the indicator is calculated. Although each municipality in the real calculations contains hundreds of thousands of pixels, in our simple numerical example we have included only 9 pixels. The number written in each pixel indicates the level of Species Richness, and it can vary between 0 and 2825. It indicates how many species can naturally live in the area out of a group of several thousand taxa indicator species (according to a 2005 study by FAN, referenced in footnote 2).<\/p>\n

Figure 1 contains two examples: (a) and (b). In both examples, 2 out of 9 pixels have been deforested (indicated in red), meaning that the deforestation rate in both examples is 22%. However, in panel (a) deforestation took place in areas with relatively low Species Richness, while in panel (b) it took place in areas with high Species Richness, leading to very different numbers for the Index of Species Disturbance (ISD): 13% in case (a) and 42% in case (b).<\/p>\n

Figure 1: Conceptualization of the Index of Species Disturbance (ISD)<\/em><\/p>\n