Objective To study the site type and quality evaluation of Eucalyptus urophylla × E. tereticornis plantation in Hainan Island and Leizhou peninsula coastal area, so as to provide reference for site selection and production potential promotion of E. urophylla × E. tereticornis plantation in Hainan Island and Leizhou peninsula region.

Method 112 plots were set up in 1- to 18-years-old E. urophylla × E. tereticornis plantations in Leizhou and Hainan. The growth indexes of E. urophylla × E. tereticornis were investigated, the site factors were recorded, and soil samples were collected to determine the soil physical and chemical properties. The quantitative theory I was used to establish the relationship model between site factors and the dominant high annual mean growth of E. urophylla × E. tereticornis, the site classification and quality evaluation of E. urophylla × E. tereticornis plantation were carried out by k-means cluster analysis and correlation analysis.

Result The multiple correlation coefficient between site factors (altitude, slope, soil depth, parent rock, pH value, soil texture, and soil density) and the height growth of the dominant tree was 0.712, which was highly significant (P < 0.01). Soil texture, parent rock and soil density were the main site factors affecting height growth of dominant trees of E. urophylla × E. tereticornis. According to these factors, E. urophylla × E. tereticornis plantation in Hainan island and Leizhou peninsula region could be divided into 12 site types. According to the suitability and productivity, the site quality was evaluated and divided into four grades: high yield group, middle yield group, low yield group and poor yield group. The total proportion of the most suitable, more suitable and suitable grades was 91.89%, which indicated that the distribution of E. urophylla × E. tereticornis plantation area in Hainan island and Leizhou peninsula region was basically reasonable. The soil factors such as pH, organic matter, total phosphorus, total potassium and available potassium had significant effects on the growth of E. urophylla × E. tereticornis plantation.

Conclusion Most of the site conditions in Hainan island and Leizhou peninsula region are suitable for the growth of E. urophylla × E. tereticornis. When planting E. urophylla × E. tereticornis plantation, it is suggested to choose the high yield group sites with acid loam soil and medium and low density. In afforestation and tending management, it is necessary to supplement phosphorus and potassium fertilizer in time to give full play to the production potential of forest land, timely replant the unsuitable site to improve the scientificity and rationality of afforestation.