Abstract: Heritage trees, important carriers of traditional culture, are important components of terrestrial biodiversity. Understanding species composition and distribution of heritage trees will provide valuable insights into heritage tree conservation. Here, we investigated the species composition and distribution of heritage trees in Wuchuan County, a minority autonomous county in Southwest China. A total of 5105 heritage trees were recorded, belonging to 79 species, 65 genera, and 38 families. The dominant families were Fagaceae, Lauraceae, Ulmaceae and Leguminosae. The dominant species were Cupressus funebris,Ginkgo biloba, Liquidambar formosana andPhoebe zhennan.Among those species, 10 were nationally protected species, including Ginkgo biloba, Liriodendron chinense, Taxus wallichianavar. chinensis, Liriodendron chinense and Nyssa sinensis.The majority of the heritage trees were concentrated in the DBH sizeclass of 50-100 cm, and the height-class of 18-26 m, and the crown sizeclass of 3-9 m. Heritage trees were mainly distributed at two types of topographic positions, with 50.49% in the valleys and 41.84% on the slopes. For habitats, 59.33% of the individuals were distributed in the villages, 13.82% were in the residential sides, and 12.14% were in the cemeteries. Heritage trees were generally well protected (more than 90% of the individuals are healthy ones). The most frequentlyoccurring damaged tree species were Cupressus funebris, Ginkgo biloba, and Cunninghamia lanceolata. Among the three species, C. lanceolata suffered the most severe damages.Overall, heritage trees in Wuchuan County with high conservation values were abundant and were relatively wellprotected.

Key words: soil structure, chlorophyll fluorescence parameter, rice yield, saline soil, polyacrylamide (PAM), biochar