Research on applying new materials for Pinus tabuliformis plantations in barren sites of plain in Beijing

To seek the implementation solutions of using new materials for the seedling survival, growth and health of large size coniferous forest such as Pinus tabuliformis under barren site condition in the Beijing Plain Afforestation Project, three new materials (i.e., antitranspirant, Suillus grevillei and GGR 6 plant growth regulator) were used to form eight different treatments. The survival rate, new shoot number, new shoot length, new shoot diameter, the content of chlorophyll and leaf nutrient elements were investigated. Results were as follows: 1) the survival rates of P. tabuliformis seedlings treated with new materials were all higher than control (78%), especially with HSK (Suillus grevillei+GGR 6 plant growth regulator+antitranspirant) treatment it was the highest (89%); 2) under the HSK treatment, the new shoots of P. tabuliformis grew best from may to July in 2013, the average increasing rate of new shoots number was greatest, and the average increasing number of individual tree was 6.48, which was 2 times of control. The average increase of new shoot diameter was 2.36 mm, which increased by 117% compared with control. The increasing amount of new shoot length increased by 251% compared with that of control; 3) the average of total chlorophyll content with HSK in 2013 was the highest of 6.96 mg/L, and the lowest of 5.76 mg/L with control. There were obvious mutual promoted effects among three new materials; 4) regarding the contents of leaf nutrient elements, under HSK treatment the average total content of element P was 0.81 g/kg, N 10.01 mg/kg and K 5.41 g/kg in 2013, which was better than the other treatments. HSK treatment could keep the contents of 3 elements stable and in high levels; 5) because dead seedlings should be replanted in order to keep the forest stand structure stable, the increase of survival rate compared with control could save the cost from replanting, then compensate the cost by applying new materials in afforestation. HSK treatment (100 plants in 0.17 hm2)can save the maximum replanting cost (810 RMB Yuan), that is 4 764 RMB Yuan/hm2. Therefore, considering all the indicators, HSK treatment can both ensure the higher survival rate and promote the growth and development of seedlings.