We established 24 experimental plots in Kráľova hoľa research site in the Low Tatra Mts. The plots were instrumented by air temperature, soil temperature and soil moisture sensors with data loggers. A complex vegetation analysis was performed including the assessment of species composition abundance, and estimation of aboveground phytomass. We installed 12 open-top chambers (OTC) in order to elevate temperature on experimental plots at the beginning of vegetation season. Continual monitoring of microclimate has preliminarily proved suitability of OTC for increasing of soil and air temperature up to 1–3 °C on average. During the whole season we regularly monitored reaction of alpine grassland ecosystem on changed microclimate and increased nitrogen inputs through the analyses of spectral vegetation indices and littr decomposition rates. The preliminary results indicate that due to high spatial and temporal variability of the simulated effcts on measured indicators, the effcts have not proven to be statistically signifiant and longer-term measurements are still necessary to reveal signifiant trends.