| As the main vegetation and constructive species in Taiyi Mountain area of the northern China,Quercus acutissima plays an important role in regulating the microclimate of inside and outside forest,controlling water and soil loss in the area,and restoring ecological vegetation.In order to investigate the changes of meteorological elements and their effects on the annual growth of the tree-ring growth in Quercus acutissima in Taiyi Mountain area,Quercus acutissima was used as the research object and this paper studied the changes of the meteorological elements inside and outside the forests and we researched the canopy interception process and redistribution characteristics of Quercus acutissima with Gash model.Moreover,we studied the influence of meteorological elements on annual tree-ring growth of Quercus acutissima by the correlation analysis method and response function analysis method.The main findings are as follows:(1)The annual average rainfall reached 850.9mm in the study area,and the rainfall was mainly concentrated on July to September.The difference in rainfall between inside and outside forest was mainly concentrated on the June to September when the trees does not grow new leaves.The total amount of effective rainfall in the observed period was 1119 mm,of which the total amount of through rainfall was 800.31 mm,accounting for 71.52% of total rainfall;the trunk flow was 25.63 mm,accounting for 2.29%;canopy interception was 293.07 mm,accounting for 26.20%.There was a non-linear relationship between the amount of litter intercepted and the through rainfall,and showed the rend of the litter intercepted gradually increased with the through rainfall increasing.The through rainfall in Quercus acutissima forests is the main form of rainfall distribution,while trunk flow is the least.The amount of through rainfall,trunk flow,and forest canopy interception showed an increasing trend with the increase of total rainfall.However,with the increase of rainfall,the rainfall that could be retained by the forest canopy becomed gradually saturated,so the rate of canopy interception increased quickly when it started raining and then gradually tended to flatten.In this study,we researched the canopy interception process and redistribution characteristics in the Yaoxiang watershed of Quercus acutissima with Gash model,and a good simulation result was obtained through the determination of parameters.However,because of some assumptions about the applicability of the model,the simulated value were generally higher than the measured interception.The simulated forest canopy interception was 307.43 mm,which was higher than the observed value by 14.36 mm and the relative error was 4.90%.The simulated value of trunk runoff and throughfall were 23.71 mm and 821.92 mm,respectively.The measured values were 25.63 mm and 800.31 mm,and the relative errors were 7.5% and 2.7% respectively.The errors of the simulation are all within the acceptable range,indicating that the model is suitable for the simulation of the rainfall interception process of the Quercus acutissima in the Taiyi Mountain.The average annual temperature in the Yaoxiang watershed was 12.9°C.The average temperature,minimum temperature,and maximum temperature of the inside forest were both lower from June to August than the outside,and the average temperature,minimum temperature,and maximum temperature of inside forest were both higher from January to March than the outside.The average temperature in July reached the maxmum and reached the minimum in December.The air humidity inside and outside the forest were higher during the rainy season from July to September.The air humidity inside and outside the forest had the largest difference in July,and the average humidity in the forest was higher than the humidity outside the forest,but the overall humidity between inside and outside the forest was not significantly differently.The evaporation inside and outside the forest reached 1770 mm and 2150 mm respectively,and showed the trend of a large evaporation in summer and a relatively small evaporation in winter.(2)The statistical analysis of the characteristics of the Quercus acutissima forest chronologies showed that both the STD and RES chronologies exhibited good correlation among their respective sequences,which was the result of similar environmental factors.The mean sensitivity(MS)exceeded the acceptable level(0.1)and indicated that the Quercus acutissima forest was sensitive to the climate factors in the study area.In addition,the common interval analysis of 1971-2015 showed that the overall sample representativenesses exceeded the acceptable level of 0.85.Thus,it can be concluded that although the response of the tree-ring growth of Quercus acutissima to climate factors was not as good as that observed in arid areas.The RES chronology contained richer environmental climate information and better represented the overall change in the study area.Therefore,the RES chronology can be used as a substitute for the response analysis of Quercus acutissima to climate factors.The tree-ring growth had a general positive correlation with the average monthly temperature,a significantly positive correlation(P<0.05)with the April temperature and a highly significantly positive correlation(P<0.01)with the May temperature of the current year.The tree-ring growth had a positive correlation with precipitation from March to June in the current year,especially a significantly positive(P<0.05)correlation with May and June precipitation,and a positive correlation with precipitation from September of the previous year to February of the current year;however,the correlation coefficients with precipitation were lower than the coefficients with temperature basically.The response function analysis showed that the temperature and humidity index were the main climate factors that influenced the tree-ring growth of Quercus acutissima,followed by the factor of precipitation.This research can provide a scientific basis for vegetation structure regulation and management,as well as an evaluation of the ecological service function of pine and oak forests in the rocky mountain area of northern China. |
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