Intra-annual stem radial growth characteristics of Pinus tabulaeformis and its response to climate on Changling Mountain
Global warming-related tree growth decline and mortality have been paid more attention around the world.To well understand the intra-annual stem radial growth characteristics of Pinus tabulaeformis and the respective roles of climatic variables on the tree intra-annual stem radial growth,the automatic dendrometer was used to continuously monitor the annual radial growth of Pinus tabulaeformis in Changling mountain of Gansu province for three consecutive years.The net radial growth data of Pinus tabulaeformis were extracted by method of mean value,and the radial growth curve was fitted by Gompertz function.Then the characteristics of intra-annual radial growth of Pinus tabulaeformis were analyzed.The response of the radial growth of Pinus tabulaeformis to temperature and precipitation was analyzed based on meteorological data and monitoring data.Finally,the relationships between the beginning time of radial growth and temperature and the mechanism of climate affecting the radial growth of Pinus tabulaeformis were discussed.The main conclusions are as follows.(1)The annual radial growth rate of Pinus tabulaeformis increased and then decreased,and the maximum radial growth rate occurred in late May and early June,and the main growth time was from May to August.The beginning time of radial growth of the two Pinus tabulaeformis was consistent,which appeared in early and middle April,but the end time was different.(2)The radial growth of Pinus tabulaeformis was negatively correlated with average temperature,maximum temperature and minimum temperature,and positively correlated with precipitation,but the strength of correlation was different between years.(3)The mean temperature threshold of the radial growth of Pinus tabulaeformis in Changling Mountain area was about 7℃.Temperature in the growing season might indirectly influence the radial growth of Pinus tabulaeformis by affecting water conditions.Abnormal precipitation might be the main reason for the excessive radial growth of the two Pinus tabulaeformis trees in June 2019.
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