| Forest wellness mechanism research is the necessary support for the vigorous development of forest health industry.At present,the understanding and activities of forest health wellness are mainly based on perceptual understanding,and lack of solid theoretical support.Many"forest health care bases"in China are unable to put forward services and products with substantial significance based on the mechanism of forest health preservation.Taking the Yuping mountain scenic spot in Hongya County of Sichuan Province as the research area,through the method of transect and typical sampling,the Cryptomeria fortunei stands with the age of 15-20 year-old、25-40 year-old and 45-60year-old were selected along the three trails（5.8 km in total）,and 500 m transect and30m×30 m transect were set respectively in the,three plots were used to determine the biogenic organic volatiles and environmental factors.The environmental factors of one secondary Sassafras tzumu stand were the control stand（CK）,The basic characteristics and mechanism of health preservation of Cryptomeria fortunei forest were studied by single factor analysis of variance and correlation analysis.The main results are as follows.（1）There was no significant difference in air temperature,relative humidity,light intensity,wind temperature and human comfort among the Cryptomeria fortunei forest of 3stand ages（P>0.05）,and there was no significant difference compared with CK（except for light intensity,the difference was significant compared with CK light intensity,P<0.05）;The wind speed of Cryptomeria fortunei was significantly different among three age groups（P<0.05）,and the difference between 25-40 year-old Cryptomeria fortunei forest was significant（P<0.05）,There was no significant difference between CK and in 15-20year-old and 45-60 year-old Cryptomeria fortunei forest.The diurnal variation of air temperature,light intensity and wind temperature showed a single peak trend,and the peak appeared at 13:30-15:00;The relative humidity showed a"V"trend,and the valley value appeared at 12:00-15:00;The climate comfort of human body shows a fluctuating trend,which is basically"grade I（s≤4.55）";The wind speed did not show obvious regularity.（2）The mean value of PM10in Cryptomeria fortunei forest of 3 stand ages was significantly different（P<0.05）.There was a significant difference between 15-20 years old Cryptomeria fortunei forest and CK,but there was no significant difference between 25-40years old and 45-60 years old Cryptomeria fortunei forest;It was 7.06μg/m3in 15-20year-old>5.19μg/m3in 45-60 year-old>CK was 4.52μg/m3>It was 3.06μg/m3in 25-40year-old Cryptomeria fortunei forestμg;The daily variation showed a"V"trend,and the trough appeared from 12:00 to 15:00.There was a significant negative correlation between PM10and negative air ions and light intensity in Cryptomeria fortunei forest from 15-20year-old;There was a significant negative correlation between PM10and air anion concentration in Cryptomeria fortunei forest from 25 to 40 years.PM10in Cryptomeria fortunei forest from 45-60 year-old was positively correlated with humidity,and negatively correlated with wind speed and light intensity.There was a significant negative correlation between PM10and air humidity.（3）There was a significant difference in the mean negative air ions among Cryptomeria fortunei forest of 3 stand ages（P<0.05）,which was significantly higher than that of CK（P<0.05）;CK was 8706.67 PCs./m3>45-60 year-old Cryptomeria fortunei forest was 2203.37 PCs./m3>25-40 year-old Cryptomeria fortunei forest was 1410.57 PCs./m3>15-20 year-old Cryptomeria fortunei forest was 998.06 PCs./m3。The highest value of Cryptomeria fortunei forest in 15-20 year-old was 1166.5PCs./m3.It appeared at10:30-12:00,and the highest value of Cryptomeria fortunei forest in 25-40 year-old was1512.83 PCs./m3.It appears at 12:00-13:30,The highest value of Cryptomeria fortunei forest in 45-60 year-old was 3155.5/m3.It appeared at 13:30-15:00;The lowest values were906.83 PCs./m3、1246.0 PCs./m3、1677.03 PCs./m3.They all appeared at 16:30-18:00;The highest value of CK was 11880.3 PCs./m3,It appeared at 15:00-16:30 and the lowest value was 6604.67 PCs./m3.At 7:00-9:00.The results showed that there was a significant positive correlation between the negative air ion concentration and the light intensity except 25-40year-old Cryptomeria fortunei forest;There was also a significant negative correlation between PM10and Cryptomeria fortunei forest in 15-20 year-old and 25-40 year-old;In25-40 year-old Cryptomeria fortunei forest,there was a significant positive correlation with wind speed and air humidity;In the secondary forest,there was a significant positive correlation between wind speed and secondary forest.（4）There were significant differences in the mean characteristics of acoustic environment quality among three age groups（P<0.05）,and the difference was significant compared with CK;The CK was 69.33d B>49.82d B in 45-60 year-old Cryptomeria fortunei forest>47.04d B in 25-40 year-old Cryptomeria fortunei forest>35.19d B in15-20-year-old Cryptomeria fortunei forest.The daily variation level is relatively stable,and the fluctuation is not more than 7d B based on the average value.（5）121 kinds of biogenic volatile organic compounds were identified from the branches and leaves of Cryptomeria fortunei,including 53 terpenes,20 alcohols,19alkanes,5 ketones,7 aldehydes,5 esters and 7 aromatic hydrocarbons.A total of 222 kinds of organic volatiles were identified in Cryptomeria fortunei forest,including 86 alkanes,37 alkenes,13 alcohols,5 ketones,9 aldehydes,30 esters,11 aromatic hydrocarbons and31 other volatile compounds.（6）The number of beneficial biogenic volatile organic compounds in fresh branches and leaves of Cryptomeria fortunei of 3 stand ages were as follows:46 species in 15-20years old,35 species in 25-40 year-old,and 55 species in 45-60 year-old;The number of trees is:35 species in 15-25 year-old,33 species in 45-60 year-old and 26 species in 25-40year-old.Naphthalene,2,4-di-tert-butylphenol,oxalic acid and so on were detected in the volatiles of all plots. |
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