Understanding responses of ecosystem processes to climate and land use change is a key challenge in ecology under both theoretical and applied aspects. So far it is not fully understood, however, how climate and land-use jointly affect ecosystem processes and services such as biomass production. The few available multi-site comparisons use species and functional trait diversity as predictors of ecosystem processes, but focus either on climate or land-use gradients. Here we propose to quantify the joint effect of land-use and climate on ecosystem processes and services. We chose the rangelands of Mongolia as study system, where precipitation gradients cover a wide range of environmental conditions. Work will be conducted at 15 localities from deserts to forest steppes, with local grazing gradients running perpendicular. We will analyse more than twenty selected focal plant species representing dominant and characteristic taxa, and measure their response to climate and land-use. The focus will be on a range of performance traits relevant for biomass productivity as the key ecosystem service in the region. This will be supplemented by a community level approach, where diversity, plant community composition and diversity of selected key traits is studied to capture responses of entire communities. We will use environmental variables and proxies for grazing as predictors for responses of both individual traits to be analysed in a Bayesian framework, as well as community responses such as species and functional diversity to be analysed with multivariate statistics. Both approaches will be combined in a synthetic modelling approach. This leads to an improved understanding of ecosystem responses with on-going global change, and represents a basis for management recommendations with respect to land-use intensity under different climate conditions in semi-arid to arid landscapes.