Abstract:

Vegetation phenology reflects the direct response of vegetation to environmental change. Although Pinus sylvestris var. mongolica were widely introduced in the desertified northern China， the effects of climate conditions of introduction area on the phenology still remain unclear. Based on the MOD13Q1 products， and meteorological data （2001-2020）， the phenology information and the temporal and spatial dynamic of P. sylvestris were explored using the maximum slope and trend analysis method， respectively. Moreover， the relations between phenology and climate factors were identified using the partial least squares regression. The results showed that： （1） The growing season of P. sylvestris started at the 100-150， 120-140， 100-140 DOY （day of year） and ended in 300-340， 270-315， 260-315 DOY in the Hulunbuir， Horqin and Mu Us Sandy Land respectively. The growing season was 170-220， 140-180， 150-200 days， respectively. （2） The initial growing season was significant earlier in the Hulunbuir， Horqin and Mu Us Sandy Land （P<0.05） with the change rates of -15.7， -5.7， -13.9 days every decade， respectively. The end of growing season was significant earlier in the Horqin and Mu Us Sandy Land （P<0.05） with the change rates of -11.7 and -16.8 days every decade， respectively. The growing season increased significantly in the Hulunbuir Sandy Land （P<0.05） with the change rate of 9.8 days every decade. （3） In the Hulunbuir Sandy Land， the early beginning of growing season was affected by the temperature reduction in August last year and the precipitation decrease in March. The late end of growing season was affected by the precipitation decrease in January. In the Horqin Sandy Land， the early beginning and late end of growing season were affected by the precipitation reduction in July last year and precipitation increase in May， respectively. In the Mu Us Sandy Land， the early beginning of growing season was affected by the temperature rise in March and the precipitation decrease in December last year， and the early end of growing season was affected by the temperature rise in September and the precipitation decrease in December last year. This improved information not only provides a better understanding of the phenology of P. sylvestris， but also contributes to the forest management towards a changing world.

Key words: vegetation phenology, growing season, Pinus sylvestris var. mongolica, climate factor, partial least squares regression