Application and analysis of two methodologies for spatialization of geodiversity indices in the Brazilian Amazon

Considering geodiversity as a complex of different abiotic elements in different taxonomic orders and geographic scales, it is important that studies look for a better scientific understanding of its quantitative distribution in space and how it can contribute or relate to other elements of nature, such as biodiversity or even the forms of appropriation by society. Taking into account the different ways in which current methodologies seek to calculate geodiversity and its distribution in each territorial portion, perhaps the greatest challenge is the standardization of scale and types of elements to be considered for infinite geographic realities. Based on these assumptions, this research aims to compare the spatial distribution of geodiversity indices using two methodologies already applied in other areas: the centroid and the one based on regular hexagonal sampling grids, applying the Shannon and Simpson diversity indices to the latter. Tests were also carried out considering different dimensions of regular hexagonal grid (10, 25, 50, 100, 250 and 500 km in the sum of the six equilateral triangles of each hexagon), being selected the one with 100 km, for presenting greater correlation with the map based on interpolation of polygon centroids. We justify the importance of this comparison because, despite having a more complex processing in relation to the centroid methodology (used as a reference), regular cells allow future correlations with point and linear bases, allowing elements of biodiversity and land use to be considered, regardless of the available spatial representation. The application in the Amazon territory was proposed aiming at the referred correlations in this area, which is one of the largest natural reserves on the planet. In a broader context, the approach adopted is justified, therefore, by the undeniable importance of this biome for humanity, which despite international recognition is intensely threatened, especially by the Brazilian environmental policy practiced in recent years. We selected as a reference map for the comparative analysis the one obtained through the interpolation of centroids with intervals established by the quartile technique, which was the one that presented the best distribution of the indexes, based on the proposed objectives. Preliminary results showed the 100km hexagonal grid as the one with the highest correlation with the subindices (lithology, soils and relief) and final maps of geodiversity indices based on centroids. Regarding the Shannon and Simpson indices, it was found that the first one presented more evident spatial correlations with the reference maps.