Comparisons of sulfur contents in leaves of 24 landscape afforestation trees in Xinxiang City

In order to explore the differences of sulfur accumulation amount in leaves of landscape green trees in Xinxiang city, 24 ornamental and afforestation trees were chosen among f ive function areas in Spring and Autumn in 2011, and the leaves sulfur contents of different trees were compared and classifi ed by K-means Cluster. The results indicate that the sulfur contents of tree leaves increased according to seasonal variation of Spring and Autumn, the season variation for some trees was signif icant, except for Ligustrum lucidum Ait. In comparison with cleaning areas, the sulfur contents of all but afforestation trees were relative higher in polluted areas. The tree species were classif ied on the basis of mean leaves sulfur contents, Populus canadensis was classif ied to the f irst category and its sulfur content was relative higher. The second category includes Buxus megistophylla, Populus alba, Ulmus pumila, Salix babylonica, Fraxinus chinensis, Acer elegantulum Fanget, Eriobotrya japonica, Buxus sinica and Ailanthus altissima, theirs sulfur contents were at medium levels. The third category included Ficus carica, Paper mulberry, Platanus hispanica, Photinia davidsoniae, Sophora japonica Linn., Ligustrum quihoui, Albizia julibrissin Durazz, Prunus cerasifera, Koelreuteria paniculata, Ligustrum lucidum Ait, Cercis chinensis, Photinia serrulata, Yucca gloriosa, Pittosporum tobira and theirs sulfur contents were at relative lower levels. The foliage sulfur contents of different tree types were different, the order ranked as following: deciduous broad-leaved arbor broad-leaved shrub evergreen broad-leaved arbor.