Grassland ecosystems are essential for biomass production but are prone to degradation if management practices are inappropriate. Thus, it is necessary to optimize grazing management since the grazing practices and grassland status are interconnected. Herbage mass production and forage quality of the plant species are among the most important factors for grazing livestock performance, grassland carrying capacity, and their sustainable management. We employed optimized methods for the analysis of two historical vegetation datasets (from 1970 and 2008), along with the statistical data on livestock numbers and types from three administrative units within the Vlădeasa Mountains area, in the Romanian Carpathians. We looked for trends in grassland quality and productivity and explored their connections to grazing management descriptors and practices. We identified a small but statistically significant decreasing trend between the two periods in both pastoral value (from 63.80 to 61.43) and productivity (from 10.80 t ha-1 to 9.18 t ha-1). The decline in grassland quality and productivity may be associated with the sharp decrease in livestock numbers (from 9,688 LU to 5,085 LU) and the replacement of cattle by sheep as the dominant livestock type. The abandonment of grasslands and traditional practices also increased the deviation from the optimum of the actual stocking rate. This approach can be used as a model for other areas where time-series vegetation data are available from phytosociological literature and/or databases. These insights can be used to design adaptive grazing management plans to optimize grazing management according to the carrying capacity of the grassland ecosystems.