重庆缙云山马尾松和润楠径向生长的酸雨响应OACSTPCD

[Objective]Acid rain caused by sulfur dioxide and nitrogen oxide emissions harms the growth of trees in southern China,it is imperative to elucidate the long-term effects of acid rain in these southern acid rain areas on the radial expansion of various tree species.[Method]In this study,Pinus massoniana and Machilus nanmu,the dominant tree species in Jinyun Mountain,were investigated with tree ring climatology 40 and 35 cores of Pinus massoniana and Machilus nanmu were collected respectively.The chronology of tree whorl width was established.And calculate the basal area lncrement.The chronology of tree ring width was established,and the increase of DBH cross-sectional area was calculated.The changes of tree growth and the response relationship between tree growth and acid rain factors in recent 20 years were analyzed.[Result]1)The overall representativeness of Pinus massoniana and Machilus nanmu standard chronology samples are 0.942 and 0.869 respectively.The overall representativeness,average sensitivity,first-order autocorrelation and interpretation of the first principal component of Pinus massoniana standard chronology are larger than those of Machilus nanmu.2)Between 1961 and 2020,both Pinus massoniana and Machilus nanmu experienced growth inhibition,and the growth inhibition time of Pinus massoniana was longer than that of Machilus nanmu,but they all recovered after 2010.3)The type of acid rain in the Jinyun Mountain gradually changed from sulfuric acid type to mixed sulfuric acid-nitric acid rain.Average temperature and precipitation are not the main limiting factors of tree growth in Jinyun Mountain in the past 20 years.The radial growth of Pinus massoniana and Machilus nanmu was significantly positively correlated with rainfall pH(P<0.05),significantly negatively correlated with rainfall SO42-(P<0.05).Rainfall NO3-was significantly negatively correlated with the radial growth of Machilus nanmu(P<0.05),and rainfall NH4+ was significantly negatively correlated with the radial growth of Pinus massoniana(P<0.05).4)Multiple linear regression model shows that annual-scale rainfall SO42-concentration and NO3-concentration had highly significant negative effects(P<0.01)on radial growth of Sargasso pine and Runner's briar,respectively,explaining 65.5％and 29.5％of the growth variance,respectively.which is the main limiting factor of tree growth in Jinyun Mountain.[Conclusion]Acid rain SO42-and NO3-are the main limiting factors for tree growth in the Jinyun Mountain area.There is great potential to use tree rings to study the effects of acid rain on tree growth.