The Temporal And Spatial Dynamics Of Main Forest Health Factors In Pure Pinus Tabuliformis Plantations And Mixed Plantations Of P.tabuliformis And Quercus Acutissima In Taishan Scenic Area

With the continuous advancement of urbanization,economic development has also brought about increasingly severe life pressure and environmental pollution,and more and more people are in a sub-healthy state of mind and body.Because of its high-quality landscape conditions and clean oxygen-rich air environment,forests have become an important place for people to relieve stress and maintain physical and mental health.The current researches on forest health and maintenance mostly compare the differences in health and maintenance effects of different communities and types of green spaces,and lack effective answers to the question of which density and mixing ratio are better for forest health and maintenance.Therefore,this study selected widely distributed P.tabuliformis forests with different densities and different mixed ratios of P.tabuliformis and Q.acutissima forests in the Taishan West Road area.Dynamic monitoring of health-related factors such as microclimate and human comfort,air particulate matter concentration,air anion concentration,air microbial concentration,noise level,comprehensively explore the spatio-temporal change characteristics and influence mechanisms of health-care factors under different forest stand structure conditions,and work for health forest management Provide reference and basis.The main results are as follows:1.Seasonal dynamics of various health factorsThe seasonal variation of temperature is summer>autumn>spring>winter.The seasonal variation and performance of relative humidity are summer>spring,autumn>winter.The wind speed value in spring and autumn is significantly higher than that in summer and winter.The seasonal variation law of human comfort is winter>spring>summer>autumn,and all seasons except winter are less than 6.95,reaching the standard of"comfort"or above.The average value of air anion concentration in all seasons except winter is more than 1000/cm³,and the seasonal variation pattern is summer>autumn>spring>winter.The seasonal dynamics of the air particulate matter concentration of four sizes of TSP,PM₁₀,PM_2.5and PM₁are basically the same,which are all expressed as autumn>winter>spring>summer.The seasonal difference of air microbial concentration is autumn>summer>spring>winter;the seasonal difference of noise value is autumn>summer>spring>winter.2.Daily dynamics of various health factorsThe temperature showed an obvious single peak diurnal variation trend,and the maximum value appeared in the range of 12:00-14:00.On the contrary,relative humidity and temperature showed a single valley diurnal variation trend,and the lowest value appeared in the range of 12:00-14:00.There is no obvious diurnal variation of wind speed.Human comfort showed a single valley trend in spring and winter,decreased with the increase of temperature,and showed a single peak trend in summer and autumn.The diurnal variation of air negative ion concentration is single peak in spring,autumn and winter,with peak value in12:00-14:00 and valley value in summer 12:00-14:00.The diurnal variation of air microbial concentration is similar to that of air particulate matter.On the whole,it is a single valley trend with high concentration in the morning and afternoon and low concentration in the noon.The lowest value appears around 12:00-14:00 noon,and the peak appears when the tourists have frequent activities in the morning and afternoon.The peak value of noise appeared at10:00 p.m.and 16:00-18:00 p.m.,and the low value appeared at 12:00-14:00 p.m.3.Differences in health factors among different mixing ratios of P.tabuliformis and Q.acutissimaThe mixing ratio has an impact on the main health factors in the forest stand.In spring,among the stands of different mixed ratios,the stands with a large proportion of Pinus tabuliformis（100%P.tabuliformis,70%P.tabuliformis and 30%Q.acutissima）have higher cooling and humidification ranges,human comfort index and air anion concentration than stands with a large proportion of Q.acutissima（100%Q.acutissima,30%,P.tabuliformis and 70%Q.acutissima）.In summer,in the two forests with a large proportion of Q.acutissim,the cooling and humidification range and the air anion concentration are higher than those of the forest with a large proportion of P.tabuliformis.In summer,the concentration of negative air ions in the 30%,P.tabuliformis and 70%Q.acutissima stands was 1672 ion/cm³,which was the annual maximum.In the autumn and winter seasons,the forest stands with a large proportion of Q.acutissima had lower temperature and humidity increase and air anion concentration than the stands with a large proportion of P.tabuliformis;In terms of human comfort level,the forests with a large proportion of Q.acutissima are higher than those with a large proportion of P.tabuliformis in autumn.The body comfort index of 70%P.tabuliformis and 30%Q.acutissima is the lowest value of 1.85 in the whole year,reaching the"very comfortable"standard.In winter,the human body comfort of the forests with a large proportion of Q.acutissima was lower than that of the forests with a large proportion of P.tabuliformis.In terms of noise,the forests with a large proportion of Q.acutissima were lower than those with a large proportion of P.tabuliformis in both autumn and winter.Among the different mixing ratios of P.tabuliformis and Q.acutissima forests,the air particle concentration and air microbial concentration of the two forests with a higher proportion of P.tabuliformis were lower than those of the two forests with a higher proportion of Q.acutissima.In the three seasons of spring,summer and autumn,the temperature and air particle concentration of mixed forest are lower than those of pure forest.The spatial distribution of various health factors in the forest stand is mainly affected by the tree species,crown width,and degree of aggregation in the area.In spring,summer,and autumn areas with high levels of mixing in the forest,air particulate matter and noise are lower than other areas,and the concentration of air anions is higher.In winter,the health factors reach a better level in the areas where P.tabuliformis is concentrated.4.Differences in health factors between different densities of P.tabuliformisDensity has an impact on the main health factors in the P.tabuliformis stand.In terms of cooling,increasing humidity,and adjusting the microclimate,the differences between different densities of P.tabuliformis forests are more consistent in each season.As the density of P.tabuliformis increases,the ability of the stands to reduce temperature,increase humidity,and adjust the microclimate increases.The comfort degree increases with increasing density in summer and autumn,and decreases with increasing density in spring and winter.In autumn,the comfort index of 1000 plant/hm²of P.tabuliformis forest is 2.02,which is the lowest value in the whole year,reaching the"very comfortable"standard.In the four seasons of spring,summer,autumn,and winter,the difference in air anion concentration among P.tabuliformis forests of different densities is low density<medium density<high density.The air anion concentration increases with the increase of the density of P.tabuliformis,and the annual maximum appears in the summer of 1000 plant/hm²（1539 ion/cm³）.At the level of air particulate matter concentration,the differences between different densities of P.tabuliformis forests,except for the PM_2.5particle size in summer and the TSP and PM₁₀particle size in autumn,which decrease with the increase in density.In other seasons,the concentration of air particles of each particle size decreases first,and then increases as the density increases.The difference in air microbial concentration levels in the three seasons of spring,autumn,and winter all showed that the concentration first decreased and then increased with the increase of the density of P.tabuliformis,and decreased with the increase of the density in summer.In terms of noise,among P.tabuliformis forests of different densities,the overall trend of noise value decreases as the density of P.tabuliformis increases in each season.The spatial distribution of various health factors in the forest stand is mainly related to the degree of tree aggregation and crown width.Areas with high density of P.tabuliformis have lower air particles,air microorganisms,and noise,and higher air negative ion concentration.5.Spatial distribution characteristics of health factorsRDA analysis results show that density,aggregation index R,degree of mixing,and crown width are the main factors affecting spatial distribution.The aggregation index R is positively correlated with air microorganisms,air particles of different sizes,and noise values,and negatively correlated with negative ions.Density,mixing degree,crown width are positively correlated with comfort and negative ions,and negatively correlated with human comfort,air microorganisms,air particles of different sizes,and noise values.Pearson correlation analysis shows that density has a significant positive correlation with negative air ions（p<0.05）,and a significant negative correlation with TSP,PM₁₀,and noise（p<0.05）.The aggregation index R is significantly positively correlated with TSP,PM₁₀,and noise values（p<0.05）.The degree of mixing,crown width and PM_2.5,PM₁were significantly negatively correlated（p<0.05）.6.Comprehensive scores of forest health factors and suggestions for recreationCombining the principal component analysis,the comprehensive scores of the health factors in each plot are ranked:100%Q.acutissima<30%P.tabuliformis 70%Q.acutissima<100%P.tabuliformis<70%P.tabuliformis 30%Q.acutissima;P.tabuliformis forest（255 plants/hm²）<P.tabuliformis forest（1000 plants/hm²）<P.tabuliformis forest（632 plants/hm²）.In the process of tending and thinning,the density of pure P.tabuliformis forest should be controlled to be about 632 plants/hm²,and the proportion of tree species in the mixed forest of P.tabuliformis and Q.acutissima should be controlled to be about 70%P.tabuliformis and 30%Q.acutissima,so as to achieve better health effect.The comprehensive scores of health factors showed a seasonal variation pattern of summer>spring>autumn>winter in general.In the spring,all the plots reached the standard of suitable recreation,and the period of 12:00-14:00 was the period with the highest comprehensive score of the whole day’s health factor.In summer,all places except 12:00-14:00 are the best time for recreation.In autumn,avoid activities in the 100%Q.acutissima,30%P.tabuliformis and 70%Q.acutissima from 8:00-10:00,and activities in the low-density P.tabuliformis forest from 8:00-10:00 and 16:00-18:00.In winter,try to avoid activities during the hours of 8:00-10:00 in the morning and 16:00-18:00 in the afternoon to reduce the impact of the severe cold weather and high particle concentration on the recreational experience in winter.Comprehensive analysis showed that the change of P.tabuliformis forest density and the change of mixed proportion of P.tabuliformis and Q.acutissima forest would affect the forest health effect of the stand.In order to improve the forest health quality of scenic forest in Taishan Scenic Area,the density of pure P.tabuliformis forest（632 plants/hm²,）should be controlled,and the proportion of tree species in the mixed forest of P.tabuliformis and Q.acutissima should be adjusted to 70%P.tabuliformis and 30%Q.acutissima,so as to achieve better rehabilitation effect.