Journal Article Research Support, Non-U.S. Gov't 27YLU75U4W Africa N762921K75 Nitrogen Phosphorus Soil atmospheric deposition carbon cycle carbon sink climate change growing degree day land surface modelling leaf onset date microbial physiology nutrient limitation phenology model phosphorus plant phenology soil biogeochemical model soil carbon classification soil carbon stabilization soil organic carbon soil physicochemical property terrestrial biosphere model tropical forest winter chilling