INTRA-ANNUAL XYLEM FORMATION DYNAMICS OF PINUS MASSONIANA IN SOUTHERN GUANGXI AND ITS RESPONSE TO CLIMATE
In order to explore the intra-annual xylem growth dynamics of Pinus massoniana in plantation forest and its response to climate in Pingxiang City,Guangxi Zhuang Autonomous Region,we selected nine 63-year old P.massoniana at the tropical forestry experiment center(22°02′N,106°51′E),sampled a total of 414 micro-cores biweekly during 2022 and 2023,and obtained the daily climatic date including temperature(maximum,average,and minimum),precipitation,relative humidity,photosyntetically active radiation,and sunshine duration of the study site.The Gompertz model was used to fit the intra-annual xylem formation dynamics of P.massoniana and mixed linear model was employed to elucidate the relationship between xylem growth rate and climatic factors.The results showed that:(1)The xylem cells of P.massoniana in southern Guangxi began to grow around the beginning of March,and reached the peak at the end of May to the beginning of June.After that,the cell growth rate gradually decreased,and maintained a slow growth in December.(2)The growth rate of xylem was significantly positively correlated with the maximum,minimum,and average temperature on 7,10 and 15 days prior to the sampling date and the sunshine duration on the sampling date(p＜0.001).Also,it was significantly positively correlated with the photosyntetically active radiation on 7,10 and 15 days prior to the sampling date(p＜0.05),and was not significantly correlated with the relative humidity and precipitation on 7,10 and 15 days prior to the sampling date(p＞0.05).These results revealed that temperature,photosyntetically active radiation,and sunshine duration could promote the intra-annual xylem formation dynamics P.massoniana and provided a theoretical basis for the management of P.massoniana under the background of future climate change.
south subtropicalPinus massonianacambiumxylemclimatic factors
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