Data in Guanacaste was collected for the years 1960, 1979, 1986, 2000, 2005, 2010. Among them, data for the years 1979, 1986, 2000, 2005, 2010 were derived from remote sensing images, and the data frame is raster. Data of 1979 came from Landsat 3, MSS image, and data of 1986, 2000, 2005, and 2010 was from Landsat 5, MSS images. The data from Landsat, MSS image has a uniform attribute, that refers to the spatial resolution is 28.5m. As remote sensing image was not available in 1960, Calvo et al. [6] compiled the land use map by digitalizing. Then this map was resampled with the uniform standard resolution (28.5m). These data were all taken at the end of wet season (around March), because at that time forests still had the almost entire leaf cover and the skies were relatively clear (no clouds). All the data which come from Landsat series satellite define World Geodetic System (WGS) 84 as reference frame and lambert conformal conic projection was used as the spatial reference according to the latitude of Guanacaste. The period of Landsat 3 is 18 days, as this parameter is 16 days for Landsat 5.
Then, the next step of processing was classification. For the data in 1960, the classes of forest areas and non-forest areas were separated when they were digitalized. For the data in the other years, Arroyo-Mora et al. [10] used a new technique to classify the forest and non-forest areas which overcame the problem with respect to the extent of tropical forests existing in previous images [11]. So forest cover maps for 6 years were acquired.
According to the Holdridge Life Zone Classification System, Guanacaste could be separated into 4 forest ecosystems. This system integrally took the annual temperature, annual participation and soil type in Guanacaste into account (see figure 3). And the forest ecosystems were tropical rain forests, tropical wet forests, tropical humid forests, and tropical dry forests. Thus, for each year data, 4 subsets data were produced, and the organization of data frame as table 1.
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