The Impact Of Environmental Changes On The Radial Growth Of Dominant Tree Species In Northeast China

In this study,the dominant conifer species(Larix gmelinii,Pinus koraiensis,Larix olgensis)and typical broad-leaved species(Betula platyphylla and Quercus mongolica)in Northeast China were selected,and the tree ring methodology was used to study the response rules of tree radial growth to the environment change.By comparing the laws of tree-environment relationships at different latitudes and different regions,it is of great significance to study the stability of various types of forests in the northeastern region,and to predict the future changes in forest vegetation in the region under the background of climate change and to establish climate change mitigation in the future.The impact on the forest has important scientific value.The article choose the climate factors and nitrogen deposition which are factors of environmental change.The correlations between the radial growth of tree rings and monthly average temperature(tmp),monthly maximum temperature(tmx),minimum monthly temperature(tmn),precipitation(pre),and self-corrected PDSI(sc-PDSI)were analyzed.Correlation analysis and spectral analysis explored the differences and synchronization of responses of different tree species to climate change.Bayesian A/B test was used to reveal the effects of nitrogen deposition on dominant tree species in Northeast China.The main results of the study are as follows:(1)Pinus koraiensis in Changbai mountain is more sensitive to climate factors(tmp,tmn,tmx)than precipitation,which is significantly positive correlation with the monthly average temperature in December,March and April of last year and the precipitation in June of that year.Larix olgensis in Changbai mountain is mainly sensitive to low temperature,which is significantly and positively correlated with scpdsi in may last year and the lowest temperature in April that year.Pinus koraiensis in Lesser Khingan Mountains is more sensitive to precipitation than temperature,which is significantly and positively correlated with the precipitation in June of that year,may and September of last year.Larix gmelinii in Greater Khingan Mountains is mainly sensitive to high temperature and precipitation,and has a significant negative correlation with the highest monthly air temperature in may last year,February of the current year and June of the current year,a significant negative correlation with the average monthly air temperature in February and June of the current year,a positive correlation with the precipitation in March and June of the current year,and a significant positive correlation with sc-pdsi in June of the current year.The combined effect of altitude,temperature and precipitation is an important factor affecting the radial growth of Betula platyphylla which is more sensitive to temperature than precipitation factors,and Quercus mongolica is more sensitive to both precipitation and temperature.(2)The cycle of Larix gmelinii in Greater Khingan Mountains is 2.6 years,3.7 years and 10 to 15 years.The cycle of Larix olgensis in Changbai Mountains is 2.3 years,4.5 years and 11±0.5 years.The cycle of Pinus koraiensis is 3.7 years and 90±2 years.It can be seen that the longest growth cycle of Pinus koraiensis.Larix olgensis in Changbai Mountain and Pinus koraiensis in Changbai Mountain have strong synchronicity,reaching a significant level of 0.1 at the cycle of 2 years and 4.2 years,and reaching a significant level of 0.05 at the cycle of 14±0.5 years.Larix olgensis in the Changbai Mountains and Larix gmelinii in Greater Khingan Mountains had a significant difference of 0.1 in the period of 4.5±0.2 years.However,the synchronization of Larix olgensis in Changbai Mountain and Larix gmelinii in Greater Khingan Mountains existed,but the response did not reach significant.(3)In Greater Khingan Mountains,low nitrogen had no significant effect on the growth of Larix gmelinii.Applying moderate nitrogen fertilizer significantly promoted the radial growth of Larix gmelinii in Greater Khingan Mountains.Although high nitrogen had no significant effect on the growth of Larix gmelinii and, it showed certain promoting effect.Nitrogen addition inhibited the radial growth of Pinus koraiensis in Changbai mountain area.Because the nitrogen addition has different effects on the growth of tree species in different regions,at the same time,the nitrogen supply of plants is closely coupled with photosynthesis,when the stimulus of photosynthesis is coupled with the increase of n on leaves,it may help to improve the water use efficiency of fertilization trees.After applying nitrogen fertilizer,the lag time of larch to temperature and precipitation may be increased,and the correlation with the early stage of the growing season of temperature and precipitation in the current year decreased,while the temperature in August and September in the current year is more beneficial to the growth of late wood.