| Every year in early October,deciduous trees in the subalpine region of western Sichuan show divers colors of red and yellow under the influence of climate,forming a unique ecological landscape.Colorful leaf forest landscape plays an important role in local tourism and regional economic development.Therefore,it is of great practical significance to explore the influencing factors and maintenance mechanism of colorful leaf forest beauty degree.It has been proved that soil elements have an effect on the perception of colored-leaf forest through colored-leaf species status and community species composition,and the perception of colored-leaf forest has a significant impact on landscape aesthetic function.Therefore,soil elements may influence the beauty of colorful leaf forest by influencing its perception.This study took the subalpine colorful leaf forest in Lixian county,Sichuan Province as the research object.Samples were obtained through plot survey,UAV photography,leaf and soil collection and questionnaire survey,and four categories of data including soil elements,landscape characteristic color,colorful leaf group color and beauty value were extracted.The influence of color leaf group color and landscape color characteristics on beauty value,the influence of soil elements on beauty value and the mediating effect of soil elements on beauty value through color leaf group color and landscape characteristic color were analyzed,so as to build a model of soil elements’ influence on beauty value.The main results are as follows:(1)The average hue and average lightness of the autumn colorful leaf group of the subalpine forest in western Sichuan have the most suitable value to the beauty degree,and the beauty degree is the highest when the average hue of the colorful leaf group is in the range of 18°～21° and the lightness is close to 0.56.When the average saturation of colored leaf cluster is in the range of 0.36～0.57,there is no optimum value for the beauty degree of the average saturation,and the beauty degree shows a monotonically increasing trend with the saturation of colored leaf cluster.The heterogeneity of light source due to environmental and spatial relationships overcomes the effect of color heterogeneity of chromophores,and the relationship between color heterogeneity and beauty is not significant.Both the average brightness and average saturation of color leaf group can improve the effectiveness of average hue to the beauty value,and the comprehensive effect of color leaf group can significantly affect the beauty value and has strong explanatory power.(2)In the overall landscape color,the color-leaf forest with high proportion of red,moderate proportion of orange,low proportion of green,low proportion of very low saturated color,moderate proportion of medium saturated color and high saturated color had higher beauty value.The improvement of the overall brightness of the plot is beneficial to the improvement of the beauty degree.Increasing the community characteristic color rather than changing the landscape as a whole was the main way that the color of colorful leaf group affected the beauty value.(3)The beauty value was significantly affected by some soil elements,and increased significantly with the increase of soil total carbon and total nitrogen,but decreased with the increase of calcium heterogeneity and the ratio of most mineral source gas to source element.C/N ratio has the most suitable value for the beauty value,p/Zn ratio has the least suitable value for the beauty value.The soil mean represented by total carbon and total nitrogen had a significant positive effect on the beauty value.The mineral gas ratio represented by iron carbon ratio and iron nitrogen ratio has significant negative effect on the beauty value.The soil elements as a whole,consisting of the mean value of positive superposition elements,the availability of C/N ratio,ore/ore ratio,element heterogeneity of negative superposition elements and ore/gas ratio,had a significant positive effect on the beauty degree.(4)The effect of soil C/N ratio on the beauty value was realized by affecting the color of colorful leaf group,and about half of the effect of soil element mean,soil element heterogeneity,soil mineral source element ratio and soil mineral gas source element ratio on the beauty value was realized by affecting the color of colorful leaf group.The characteristic color of landscape is the way that soil elements affect the beauty degree,and the color of colorful leaf group is an important part of landscape color.The results showed that soil elements could influence the beauty degree to a certain extent,and community characteristic colors played a major bridging role in the process of soil elements influencing beauty degree.Color leaf group color is the key factor of community characteristic color in the process of soil elements influencing the beauty degree.The contribution of soil elements to the beauty degree indicated that the following measures should be taken to increase soil carbon and nitrogen,adjust soil carbon and nitrogen ratio,reduce the antagonism between phosphorus and zinc,and reduce the stress of key points.The results of this study can be used as the basis for adjusting soil elements to improve the quality of colorful leaf forest in autumn in western Sichuan,and provide important scientific guidance for the maintenance of colorful leaf forest in autumn. |
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