Structural connectivity in the Lower Uruguay River Forest

ADRIANA ROJAS; MARIEL BAZZALO; NATALIA SOLEDAD MORANDEIRA

Zurich

Conferencia; useR! 2021 - The R Conference; 2021

The R Foundation

In recent decades, a process of agricultural expansion took place in the wetlands of the lower Uruguay River that leading to the fragmentation of the landscape. We aimed to estimate the structural connectivity of the hydrophilic forest and the open forest, in the basins of the main tributaries of the Lower Uruguay River for the years 1985, 2002 and 2017. Our inputs were landcover classifications previously generated by the authors with Landsat imagery. For each date, the study area (339.000 km2) was subdivided into 49800 cells of 1Km2. The connectivity is estimated by calculating 14 landscape metrics in each of the 49800 cells, for each of the dates. The spatial representation of the connectivity indices was processed using the sf, tidyverse and dplyr packages. Subsequently, we performed a PCA analysis to reduce the dimensionality of the connectivity analysis and propose a simpler connectivity index without redundant variables, the stats, FactoMineR and factoextra packages were used. The variables with the highest score in components 1 and 2 of the PCA (which explain the greater variability) are graphically represented for one of the cells. Our proposed index is based on four landscape metrics: class area, number of patches, landscape shape,and area-weighted mean patch area. Based on this index, we identified areas with low/high connectivity of the forests, and trends in connectivity changes during the study period.