Relationship between leaf area index and climate factors in a Quercus variabilis plantation at the southern foot of Taihang Mountain from 2001 to 2019

Quercus variabilis is one of the most widely distributed natural tree species in China. The southern foot of Taihang Mountain is one of the key areas of forestry engineering in China, which is sensitive to climate change. The study on the relationship between leaf area index（LAI） of Quercus variabilis plantation and climate factors in this area is of great significance to the construction of forestry ecological engineering and the evaluation of temperate forest carbon sink function in China. In this study, a 40-year-old mixed plantation（Quercus variabilis, Robinia pseudoacacia and Platycladus orientalis） in the southern foot of Taihang Mountain was taken as the research object. Firstly, we corrected the MODIS LAI product from 2001 to 2019 by using measured LAI data. Secondly, we analyzed the climate change trend in the research area in recent 19 years. Finally, we analyzed the variation characteristics of LAI and discussed the relationship of LAI and climate factors. The results showed that the climate in the experimental area was warming and humid from 2001 to 2019. The rising rate of temperature is 0.70℃·per ten years. The temperature increase in the growing season was higher than that in the non-growing season. The precipitation in growing season and-non growing season increased and decreased, respectively. In recent 10 years, the trend of climate warming and humidification has accelerated, and the frequency and intensity of high-temperature weather have increased. The LAI showed an increasing trend, the average value in recent 19 years was 2.09, and the growth rate was 0.21/10a. The growth rate of LAI in near-mature forest period was lower than that in middle-aged forest period. Temperature was the dominant climatic factor affecting the seasonal and inter-annual variation of LAI, and precipitation mainly affected the seasonal variation of LAI. The LAI in the years with high temperature days higher than 35 days was lower than that in the previous year in the near-mature forest period.