Effects Of Chinese Fir Plantation On Air Temperature And Humidity At Different Growth Stages

In this paper,the author used the observation data of the long-term localization of air temperature and humidity in Chinese fir forest by the National Field Science observation and Research Station of Chinese fir forest ecosystem,the temporal variation of air temperature and humidity difference between inside and outside of the Chinese fir plantation at different growth stages was studied,the effects of Chinese fir forest on temperature and humidity at different growth stages were revealed.The main conclusions are as follows:(1)At different growth stages,the average diurnal variation of air temperature difference between inside and outside of the Chinese fir forest is single peak.The effect of cooling is the strongest in the afternoon and the effect of cooling is the weakest at night,the cooling effect is stronger in summer than in winter,and it is larger on sunny days than that on cloudy day.In some months of autumn and winter at night near mature stage and at the mature stage,Chinese fir forest showed warming effect.Between outside and inside of the Chinese fir forest,the mean annual variation of mean monthly temperature difference,mean maximum monthly temperature difference and mean daily mean monthly temperature difference was single peak,and it was larger in summer and spring than that in autumn and winter.The maximum annual average value of the monthly average temperature difference appears in the mature stage,which can reduce the temperature in the forest by 1.99℃.The maximum annual average of the maximum monthly temperature difference and the monthly average daily difference appeared in the near mature stage,which were 2.97℃ and 2.92℃ Crespectively.The annual mean monthly minimum temperature was higher outside the forest than that in the forest at the young stage and the rapid growth stage,but in some months of autumn and winter in the near mature stage and mature stage,the Chinese fir forest showed a certain warming effect.The maximum temperature in the forest is 0.57℃ Chigher than that outside the forest.With the increase of forest age,the regulating effect of Chinese fir forest on temperature increased on sunny days in spring,summer and autumn,and the maximum appeared in the mature stage,which could reduce the monthly average temperature in the forest by 2.15℃.The regulating effect of Chinese fir forest on temperature is larger on sunny days than that on cloudy days,especially in summer.In winter,at the near mature stage and mature stage,Chinese fir forest showed certain warming effect,and the warming effect on sunny days is greater than that on cloudy days,and the maximum monthly average temperature in the forest is 0.25℃ Chigher than that outside of the Chinese fir forest.(2)At different growth stages,the average diurnal variation of relative humidity difference between inside and outside of the Chinese fir forest is single peak.The maximum appears in the early morning and the minimum appears in the afternoon.The humidification of afternoon of the Chinese fir forest is greater in summer than in winter,sunny day is bigger than cloudy day and increases with the increase of forest age,the maximum appears at the maturity stage at 14:00 in July,the Chinese fir forest is 16.47%higher than outside of the Chinese fir forest.At the young stage and at the fast-growing stage,the annual average of the relative humidity difference inside and outside of the Chinese fir forest in summer is slightly smaller than in winter,the summer is significantly smaller than the winter at the near-mature stage and at the mature stage.The monthly average relative humidity difference and the monthly average minimum relative humidity difference inside and outside of the Chinese fir forest are increasing with the increase of the Chinese fir forest age,the maximum differences are 8.84%、-16.85%at the maturity stage,the difference of monthly average maximum relative humidity decreases with the increase of the Chinese fir forest age,the minimum is 4.90%at the maturity stage,and the difference of the monthly average relative humidity is increasing,the maximum is 12.5%at the maturity stage.(3)At different growth stages,the maximum value of the average annual diurnal variation of the water vapor pressure difference between inside and outside of the Chinese fir forest appears in the early morning,and the minimum value appears in the afternoon,the humidification effect of Chinese fir forest at 14:00 of sunny days is bigger than cloudy days,summer is stronger than winter and increases with the increase of the Chinese fir forest age.The maximum appears in the mature stage at 14:00 in July,the water vapor pressure in the Chinese fir forest is higher than the 4.59hPa outside of the Chinese fir forest.The maximum difference of monthly average water vapor pressure between inside and outside of the Chinese fir forest at different growth stages appears from July to October,and the minimum appears in November or January to March.With the increase of the Chinese fir forest age,the monthly average water vapor pressure difference and monthly average minimum water vapor pressure difference are increasing between inside and outside of the Chinese fir forest,the maximum are 1.28hPa、-2.75hPa and they appear at the mature stage in July.The monthly average maximum water vapor pressure difference is decreasing and the minimal is 0.74hPa at the maturity stage.But the range of monthly average water vapor pressure difference is increasing and the maximum is 2.57hPa at the maturity stage.