Leaf chlorophyll content is the crucial factor for the temporal and spatial variation of global plants leaf maximum...

Photosynthesis plays an important role in the terrestrial carbon and water cycles which are often studied using terrestrial biosphere models (TBMs). The maximum carboxylation rate at 25 °C (V_cmax25) is a key parameter in the photosynthesis module of TBMs, yet the spatiotemporal distribution of V_cmax25 and the driving mechanism are not fully understood. In this study, Enzyme Kinetics response model, leaf chlorophyll content response model and partial correlation analysis were used to analyze the temporal and spatial changes patterns of atmospheric environment, enzyme dynamic and soil nutrition on V_cmax25 and the driving mechanism, and has made a few useful conclusions: (1) V_cmax25 varies significantly with latitude and between- and within-plant function types (PFTs), which mainly dependent on leaf chlorophyll content (LCC). Under the influence of temperature, the contribution of LCC to the seasonal variation of V_cmax25 is very different among the eight main biomes, with an average contribution of 21 %. (2) The relationship between meteorological variables and V_cmax25 was significant, due to the fact that meteorological variables drive the Rubisco enzyme content that have a significant relationship with V_cmax25, rather than directly acting on V_cmax25. (3) Soil nutrient elements had significant influence on the spatiotemporal variation of V_cmax25 and LCC. The results showed that soil total carbon, soil nitrogen and organic carbon not only affect the temporal and spatial pattern of V_cmax25, but also are the key factors of LCC temporal-spatial variation. These findings provide useful information for better parameterization of V_cmax25 in TBMs.