Response Regimes Of Radial Growth For Main Tree Species To The Abnormal Climate Change In Northeast China

Since the 20th century,the global climate has witnessed an increasingly extreme change symbolized by the global warming,but the trend often fluctuates moderately or suddenly,rather than increase at a steady pace.Meanwhile,the seasonal difference and regional difference also exist in the temperature change.The influence of the climate change may vary from region to region,but always causes more damage to the eco-crisis zone than benefits.Moreover,the warming climate can exacerbate the intensity and frequency of extreme weather events,which is a bitter blow towards the social economy.The northeastern area is located in the middle and high latitude zones in China,which belong to the sensitive and vulnerable climate areas featuring irregular radical climate changes.Climate change in Northeastern China can be affected by the global warming,while it also possesses typical regional characteristics.The northeastern forest area is the largest forest system in China,whose dominant components are temperate coniferous broad-leaved mixed forests and boreal coniferous forests.Both of the areas are typical ecological fragile area,and even a tiny alteration can lead to an apparent effect.Under such circumstances,this paper utilizes the tree-ring data of Pinus koraiensis,Quercus mongolica,Fraxinus mandshurica,Pinus sylvestris var.mongolica,and Larix gmelinii in northeastern area(Changbai Mountain,Xiaoxing'an Mountain,Daxing'an Mountains)to analyze the difference and consistency of the same tree species in diverse areas,diverse tree species in the same area,and the diverse tree species in the diverse areas response to three typical climate events.Some interesting research findings are discussed in the following below.(1)In Changbai Mountain,within the same area,the difference of the climate-growth relationships of the three tree species are significant.In comparison with the radical growth of P.koraiensis demonstrates a considerable dependence on the temperature changes;the radical growth of Q.mongolica which are mainly affected by moisture and temperature,and the influence of moisture condition is stronger than temperature;the radical growth of F.mandshurica is affected by the temperature and moisture,and the influence of temperature is stronger than moisture condition.This suggests that climate-growth relationships are affected by species-specific characteristics.Moreover,even under the same climatic conditions,the trees of homogenous species in different areas also present difference.With the descended latitudes(in three sampling sites,namely Laobai Moutain,Lushuihe,Hongshi),the correlation between the radical growth of P.koraiensis and soil moisture conditions of growing season(from June to September)varies from significantly positive correlation,negative correlation to positive correlation,while the positive correlation with temperature is reduced gradually.Meanwhile,the correlation between the radical growth of F.mandshurica and soil moisture conditions of growing season varies from significantly negative correlation,negative correlation to positive correlation,while the positive correlation with temperature is reduced gradually.In the two sampling sites(Hongshi,Lushuihe),the correlation between the radical growth of Q.mongolica and soil moisture conditions in growing season varies from significantly positive correlation to negative correlation,and varies from negative correlation to positive correlation with temperature.In Xiaoxing' an Mountain,within the same area,the difference of the climate-growth relationships of the three tree species are significant.The radical growth of P.koraiensis is affected by the temperature,especially the minimum temperature;the radical growth of Q.mongolica is limited by the moisture;the radical growth of F.mandshurica is affected by both temperature and moisture,and the influence of temperature is stronger than moisture condition.This finding also indicates that species properties to some extent influence the relation between plant growth and climate factors.Moreover,even under the same climatic conditions,the trees of homogenous species in different areas also present difference.With the descended latitudes(in three sampling sites,namely Hebei,Liangzihe,Yongxing),the correlation between the radical growth of P.koraiensis and soil moisture conditions of growing season(from June to September)varies from negative correlation,weak correlation to positive correlation,while the positive correlation with temperature is reduced gradually.Meanwhile,Q.mongolica in the three sampling sites prove to have significant positive correlation with moisture conditions of growing season and the negative correlation with temperature decreases.The positive correlation between F.mandshurica in the two sampling sites(Hebei and Yongxing)and the temperature in growing season was enhanced gradually.There was no significant correlation between the radical growth of F.mandshurica and moisture conditions in growing season,but that correlation in early growth season enhanced gradually.In Daxing'an Mountains,Pinus sylvestris var.mongolica and Larix gmelinii are mainly constricted by both temperature and moisture.The influential degree differs owing to the diverse climate conditions in sampling points.With the descended latitudes(in four sampling sites,namely Tuqiang,Moerdaoga,Jinhe,Along Mountain),the positive correlation between the radical growth of P.sylvestris var.mongolica with temperature of growing season(from June to September)is reduced gradually.Meanwhile,Larix gmelinii in the three sampling sites(Along Mountain,Jinhe,Moerdaoga),the correlation between the radical growth of L.gmelinii and soil moisture conditions of growing season(from June to September)varies from positive correlation,negative correlation to positive correlation,while the negative correlation with temperature is enhanced gradually.(2)After 1980,the performance of anomaly warming's influence on the radial growth of P.koraiensis is distinct in each sampling site.Differentiation phenomenon,which means growth declines with the rising temperature,did not appear in the P.koraiensis growth in North Jilin Province of Laobai Mountain but in Midwest Heilongjiang Province of Liangzihe area.Meanwhile,the P.koraiensis growth in Mideast and South Jilin Province of Hongshi and Lushuihe showed the tendency of a slowing-down growth rate.The influence on P.koraiensis growth in East Heilongjiang Province of Yongxing is not so apparent.Besides,the tree-ring is widened as the increase of the temperature in Hebei Forestry Bureau.The Q.mongolica in Yongxing Forest Farm,which showed a rising tendency as the warming temperatures,other four sampling sites(Hongshi,Lushuihe,Hebei and Liangzihe)did not present significant changes.As for F.mandshurica in five sampling sites(Hongshi,Lushuhe,Laobai Moutain,Hebei and Yongxing),they all changed with the fluctuation of the temperature.The differentiation phenomenon of P.sylvestris var.mongolica appeared in Northwest Daxing'an Mountains but not remarkable,in contrast,the P.sylvestris var.mongolica increased with the rising temperatures in Heilongjiang Province of Yongxing.The radial growth of L.gmelinii in three sampling sites(Along Moutain,Jinhe and Moerdaoga)did not change with the rising temperatures.With the rising temperatures and changing precipitation pattern,the comfort zone for P.koraiensis might move northward.This phenomenon was not found in Q.mongolica and F.mandshurica.Conversely,the degradation phenomenon of P.sylvestris var.mongolica in Daxing'an Mountains might be exacerbated,and L.gmelinii in certain areas also would experience the same responses.(3)The relationship between the characteristics of tree growth in Northeast China before and after PDO phase transition in 1976/1977 and PDO also experienced different changes.Before 1977,the relationship between the tree-ring of F.mandshurica and PDO system was not significant;after 1977,the tree-ring of F.mandshurica in five sampling sites as well as the PDO index experienced a significantly enhanced trend;but PDO system had little effect on the radial growth of Q.mongolica in five sampling sites.After PDO phase transition,P.koraiensis in different sampling sites reacted differently.After 1977,the PDO index was positively correlated with the tree-ring of P.koraiensis in North site,but in other sites,the tree-ring of P.koraiensis was separated from PDO index,which denotes that the change of climate that resulted from the change of PDO system would have a negative impact on the radical growth of P.koraiensis in some sites,causing a recessionary phenomenon.It is worth noticing that the similar research results have also existed in the research of P.sylvestris var.mongolica in Daxing'an Mountains and in the research of L.gmelinii.(4)ENSO events affect the local climate in Northeast China,which affects the radial growth of some trees.There is a significant correlation between the temperature and the ENSO index in the low frequency in Northeast China,which indicates that ENSO has long-term effect on the local climate.Meanwhile,the superposed epoch analysis is found that ENSO events negatively affected on the radial growth of P.koraiensis in Hebei and Liangzihe,but positively affected on that of P.koraiensis in Hongshi,Lushuihe,Laobai Mountain and Yongxing.ENSO events negatively affected on the radial growth of F.mandshurica in Hebei and Liangzihe,but positively affected on that of F.mandshurica in Laobai Mountain and Yongxing.ENSO events negatively affected on the radial growth of Q.mongolica in Hebei and Yongxing,but positively affected on that of Q.mongolica in Hongshi and Lushuihe.ENSO events negatively affected on the radial growth of P.sylvestris var.mongolica in Along Mountian and Moerdaoga,but positively affected on of P.sylvestris var.mongolica in Jinhe.In addition,ENSO event not only affected the growth of trees in Northeast China in that particular year,but also has a significant impact on the growth of tree in the first year,the next one year and the next two years.