| As the global economy has boomed in recent years and due to an increasing number of people having sub-optimal health status,forest convalescence has emerged as a comprehensive healthcare industry.Due to lack of a theoretical basis support,the industry of forest convalescence is hindered.To solve this problem,in this study,Mount Lu is taken as the main research area and typical forest types(evergreen broad-leaved forest,coniferous forest and bamboo forest)are chosen and major factors related to forest convalescence including airborne particulate matter,negative air ions,oxygen,biogenic volatile organic compounds(BVOCs)and human comfort are identified and systematically studied to determine how these key factors change and their governing laws with respect to multiple dimensions such as time and space.This study also explores the relationship between these factors to reveal the underlying change mechanisms,and the key impact factors are clarified.Moreover,the forest convalescence activities suitability index(FCASI)was constructed,an evidence-based medical system evaluation method was applied and an empirical test study of the factors affecting forest convalescence was conducted.(1)Time dynamics of forest convalescence.The concentration of airborne particulate matter changes dynamically according to the following laws: with respect to diurnal variation,the concentration is low in the morning but high at noon and afternoon;with respect to seasonal variation,the concentration is high in winter but low in spring,summer and autumn.The concentration of negative air ions changes dynamically according to the following laws: with respect to diurnal variation,the concentration is high in the morning and evening but low at noon and afternoon in spring,autumn and winter and during summer,the concentration is high in the morning and early morning but low at noon and afternoon;with respect to seasonal variation,the concentration of negative air ions in summer is higher than the concentration occurring in spring,autumn and winter.The oxygen content changes dynamically according to the following laws: with respect to diurnal variation,the content is low in the morning and early morning but high at noon and afternoon;with respect to seasonal variation,the oxygen content exhibits the following relative order: summer > spring > autumn > winter.The levels of human comfort change dynamically according to the following laws:with respect to diurnal variation,in spring and autumn,the comfort level is high at noon and afternoon but low in the morning and evening.The comfort level varies slightly during a day in summer and winter;with respect to seasonal variation,the comfort level exhibits the following relative order: summer > spring > autumn > winter.(2)Spatial variation characteristics of forest convalescence.In the 150–930 m altitude range of this study.The concentration of airborne particulate matter was found to decrease inversely with increases in altitude.The concentration of negative air ions was not found to change with the vertical location on the mountain.The oxygen content was found to decrease inversely with increases in altitude.The human comfort level was found to increases with increases in altitude.(3)Differences in health care potential of different tree species.Among the three selected tree species,a ranking of their annual average number of beneficial BVOCs is as follows: 42 species of Cinnamomum camphora > 34 species of Cryptomeria japonica > 13 species of Phyllostachys edulis;the ranking of the annual average concentration of beneficial BVOCs: Cryptomeria japonica(80.08%)>Cinnamomum camphora(43.01%)> Phyllostachys edulis(7.66%).Cryptomeria japonica ranked first in its therapeutic effect of BVOCs,Cinnamomum camphora ranked second and Phyllostachys edulis ranked at the bottom.(4)The key factors and interaction mechanism of elements in forest convalescence.The key factors affecting the concentration of airborne particulate matter are the concentration of negative air ions,wind speed and air pressure,in that order.An increase in the negative air ions concentration reduces the concentration of airborne particulate matter >the increase of wind speed reduces the airborne particulate matter > the reduction of air pressure reduces the airborne particulate matter.The key factors affecting the concentration of negative air ions are the concentration of airborne particulate matter and the air temperature,in that order.A decrease in the airborne particulate matter concentration increases the negative air ions concentration > an increase of air temperature increases the negative air ions concentration.The key factors affecting oxygen content are air temperature and air pressure,in that order.A decrease in air temperature reduces the oxygen content > a decrease in air pressure reduces the oxygen content.The key factor affecting beneficial BVOCs is air temperature.The number of beneficial BVOCs change with the periodic rhythm of a plant’s physiology.An increase in air temperature increases the number of BVOC.On the whole,a change in the concentration of beneficial BVOCs is mainly affected by the air temperature.As the air temperature rises,the concentration of alkanes decreases,whereas that of olefins increase.As olefins are critical components of beneficial BVOCs,an increase in the olefins concentration also increases the number of beneficial BVOCs.(5)Evaluation of suitability of forest convalescence activities on Mount Lu.By constructing a FCASI based on temporal and spatial laws and the characteristics of forest convalescence elements,the most suitable times for forest convalescence activities at Mount Lu were found to be morning and early morning.The most suitable seasons for forest convalescence activities were found to be spring and summer,followed by autumn.The most suitable forests for forest convalescence activities were identified as the Cryptomeria japonica forest and Phyllostachys edulis forest,followed by evergreen broad-leaved forest.The suitability of providing forest convalescence activities in the high-altitude areas of Mount Lu is greater than that in low-altitude areas,and in winter,no forests are suitable for forest convalescence activities.(6)Empirical research results on forest convalescence.From the medical perspective,improving the quality of the research methodology will increase the evidence level of the empirical results.Exposure to the forest environment has been found to significantly reduce the blood pressure,pulse rate and ln LF/ln HF of heart rate variability(HRV)in humans,while significantly increasing the ln HF of HRV,thereby enhancing the parasympathetic nerve activity and reducing the sympathetic nervous activity,especially for females in whom the parasympathetic activity enhancement effect is more significant.After exposure to the forest environment,the human body experiences a significant reduction in its negative emotional state and a marked increase in positive emotions,especially for males whose improvement in emotional state is more significant.In summary,the elements associated with forest convalescence have spatiotemporal variability and the interaction among them and other environmental factors is the cause of this variability.To manage the changes associated with the elements of forest convalescence,forest land types with higher potential for BVOCs care should be selected and FCASI should be used to guide forest convalescence activity.The application of this model overcomes the current subjective and qualitative evaluations of the health potentials of forests.This objective and quantitative evaluation method can be provide quantitative forest environmental conditions for empirical research and to improve the evidence level of the research results from the forestry perspective. |
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