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Coefficient C is a synthetic index from the third correlative equation, which represents the state of moisture in a region and may be used for assigning vegetation zonality. The third correlative equation is a new equation concerning heat and water balance from knowledge of evaporation on land. In this article, coefficient C and accumulated temperature over 5 degrees C (AT5) are combined to predict the distribution of vegetation zones in China. Predictions of vegetation distribution are made using observational climate data interpolated into a 25 x 25 km grid.

The overall impression from examining the resulting vegetation map is that the location and distribution of vegetation zones in China are predicted fairly well. Comparison between the predicted vegetation map and the vegetation regionalization map are based on Kappa statistics and indicate very good agreement for the cold-temperate coniferous forest zone, the subtropical evergreen broadleaved forest zone, and the temperate mixed coniferous-broadleaved forest zone. Agreement is good for the warm-temperate deciduous broadleaved forest zone, the temperate steppe zone, the temperate desert zone, and the Tibetan high-cold plateau zone. Agreement between the regionalization map and the produced map is fair for the tropical rainforest and monsoon forest zone.

Compared with those produced by the Holdridge, Thornthwaite, Penman, and the Kira models, as well as the Budyko method, the Kappa statistics in this article are all better except for the cold-temperate (boreal) coniferous forest zone and the temperate desert zone. The results are particularly superior for the Tibetan high-cold plateau zone. Coefficient C provides important information for predicting the distribution of vegetation zones in China, and this article attempts to study vegetation-climate classification on a large scale using coefficient C and AT5. Copyright (C) 2007 Royal Meteorological Society.