Grassland ecosystems are among the most threatened by degradation and habitat loss, and by encroachment of woody vegetation. Our research in subtropical alluvial grasslands in Northeastern India (and through collaborations in in alpine meadows in Tibet/China) has shed light on the importance of habitat factors, competition, facilitation, fire, climate, dispersal, plant invasions, and stochasticity for the diversity and structure of grassland ecosystems. In the Terai ecosystems, we have documented decadal scale changes in the extend of woodland and grasslands and have examined the potential drivers of changes in savanna and grassland vegetation in many sites. We propose several measures needed for the management of these ecosystems to conserve plant diversity and wildlife habitats. Prominent results published in Agricultural and Forest Meteorology, Plant Ecology, PloS One, Ecography, Oecologia, and Forest Ecology and Management.