Landscape dynamics of Paspalum quadrifarium grasslands analyzed by Morphological Spatial Pattern Analysis (MSPA)

Background. Despite its wide distribution worldwide, only 4.6% of temperate grasslands are included within systems of protected areas. In Argentina, this situation is even more alarming: only 1.05% is protected. The study area (central area of the southern Salado River basin) has a large extent of grasslands of Paspalum quadrifarium (Pq) which has been target since the last century of a variety of agricultural management practices including fire burning for cattle grazing. Methods. Binary images of presence-absence data of Pq from a 42-year (1974-2016) land cover change study were used as base data. MSPA (Morphological Spatial Pattern Analysis) and Network Analysis were performed to the data using Guidos Toolbox for the estimation of habitat and connectivity dynamics of the Pq patches (fragments). Results. A loss of the coverage area and habitat nuclei of this grassland was observed between the beginning and the end of the study period. A drastic reduction in connectivity was also evident in resulting maps. The number of large Pq grassland fragments (> 50 ha) decreased during the study period, and fragmentation measured as number of components (patches) was higher at the end of study period. The Pq pajonal nuclei had their minimum representativeness in 2000, and recovered slightly in 2011, but with a significant percentage increase of the small patches (=islets) and linear elements as bridges and branches. Large corridors (mainly edge of roads) could be observed at the end of study period, while the total connectivity of the landscape pattern drops abruptly. Discussion. The habitat reduction could have an impact on the ecosystem functioning and the mobility of some species of native fauna. The connecting elements of the landscape were maintained and/or recovered in percentage in 2011 and 2016. This fact, although favoring the dispersion of the present diversity in the habitat nuclei could cause degradation by an edge effect. On the methodological side, the use of a proved tool as Guidos Toolbox for evaluating forest fragmentation could also be useful for monitoring dynamics of a grassland-habitat fragmentation.