Relationship between phenology of vegetation canopy and phenology of tree cambium in Helan Mountains, China.

Based on 98 Chinese pine () tree-ring width data, normalized diffe-rence vegetation index (NDVI) data and land cover data in the Helan Mountains, we used VS-oscilloscope model to simulate the radial growth process of Chinese pine and to examine the relationship between vegetation canopy phenology and tree cambium phenology. Results showed that the end of season (EOS) of the vegetation canopy was significantly correlated with the EOS of the Chinese pine cambium. Such correlation was stronger than that between grassland and cambium. The start of season (SOS) and EOS of Chinese pine were related to the averaged minimum temperature in May-June and August-September, respectively. When the average minimum temperature in May-June increased by 1 ℃, SOS would be advanced by 4.3 days. The averaged minimum temperature in August-September increased by 1 ℃, EOS would be delayed by 2.6 days. The correlation between the phenology of vegetation canopy and the phenology of the cambium in Chinese pine differed among vegetation types. Simulating tree growth dynamics only through a tree-ring physiology model might lead to biased results. Using remote sensing monitoring data to combine canopy development and cambium growth would help to more accurately understand tree growth dynamics.