A Study on the Relationship between Tree Ring Width Index and NDVI of Larix gmelinii

To explore the relationship between radial growth and NDVI（Normalized Difference Vegetation Index） of Larix gmelinii, and to provide reference for understanding tree growth dynamics, based on Larix gmelinii at Tahe sampling point from 1973 to 2018, GIMMS（Global Inventory Modelling and Mapping Studies） NDVI data set from 1982 to 2018 and climate factors（precipitation, monthly mean temperature, monthly mean minimum temperature, monthly mean maximum temperature） was analyzed in this paper. Results showed that the tree ring width index was significantly negatively correlated with the mean temperature in June, July and June-July（P＜0.05）, and significantly negatively correlated with the mean maximum temperature in June, July and June-July（P＜0.05）. NDVI was significantly negatively correlated with the mean minimum temperature and monthly mean temperature in December last year（P＜0.05）, significantly positively correlated with the mean temperature in May, the mean maximum temperature in May and the mean temperature in July（P＜0.05）, extremely positively correlated with the mean maximum temperature in July, August and July-August（P＜0.01）. There was no significant correlation between tree ring width index and NDV in July of that year, but a significant positive correlation between tree ring width index and NDVI in July of last year. It can be concluded that the mean maximum temperature from June to July was the main controlling factor of tree radial growth, and the mean maximum temperature from July to August was the main controlling factor of tree canopy growth. The control factors of trunk growth and canopy growth were different, and the growth status of canopy was different from that of trunk.