The difference in leaf color quality of Cotinus coggygria during the coloration peak period affected by soil and topographic heterogeneity

Abstract

Leaf color quality that measures the gorgeous degree of plant’s foliage with a specific color during a coloration period, has been related to the biological function of colored plants and the development of ecotourism. The difference in leaf color quality of Cotinus coggygria and its key environmental factors during the coloration peak period in a karst area were explored based on leaf color parameters (i.e., L*, a*, b*, and c*), pigment indices (i.e., chlorophylls, carotenoid, anthocyanin, myricetin, quercetin, and kaempferol), and environment variables (i.e., soil properties, topography, and vegetation community characteristic) by principle component analysis, random forest model, and hierarchical cluster analysis. The results indicated that the leaf color quality index based on the minimum data set including the total chlorophyll, anthocyanin, and quercetin could accurately reveal the difference in leaf color quality of Cotinus coggygria in our study area. The coefficient of variation in leaf color quality index was 25.47%, which suggested that the leaf color quality of Cotinus coggygria had spatial heterogeneity. This heterogeneity was closely related to soil properties (e.g., total phosphorus, total potassium, and available potassium) and topographic variables (e.g., slope height and elevation). Specifically, the leaf color quality of Cotinus coggygria was higher in the middle- and low-elevation areas with less soil nutrients (i.e., total phosphorus, total potassium, and available potassium) and higher slope height, but lower in the high-altitude areas with more soil nutrients and lower slope height. Moreover, the leaf color quality of Cotinus coggygria in shrubbery was higher than that in mixed forest, suggesting that the vegetation community characteristic is another important factor of the leaf color quality in the study area. These results can provide a theoretical basis to quantify the difference in leaf color quality of colored plants during the coloration peak period and improve the ornamental value of colored plants in rocky desertification areas.