This work aimed to analyze the landscape evolution of the Paraíba do Sul River Valley (states of RJ, MG and SP) from the 19th century s coffee plantations to the present pasture scenario, identifying the socioecological consequences of this transformation. Field data (semi-structured interviews and direct observation), agricultural and demographic census data, and historical documents were combined. Fieldwork was carried out in the municipality of São José do Barreiro - SP. The objective was to gather the individual and collective memories of cattle ranchers and ex-herdsmen on the distribution of two grasses, the greasy grass (Melinis minutiflora P. Beauv.) and the brachiaria (Urochloa spp.), over time. Due to the low volume of documentation found on the formation of livestock activity in the region, the reports collected during the interviews facilitated the understanding of the landscape transition, notably the distribution of the grasses in them. The explanations for the decrease in coffee-growing activity and the growth of livestock in the region could not be explained only by socioeconomic facts. It should be emphasized the role that the physical-ecological factors, especially the eco-physiological characteristics of the two species of grasses, played in the shape of the Paraíba do Sul River Valley current landscape.