Abstract:

Aims Pinus massoniana and Schima superba are important coniferous and broad-leaved species, respectively, in timber plantations in the subtropical mountain area of China. Our aim was to elucidate the effects of competition on foraging behavior of these two species in a heterogeneous nutrient environment to provide scientifically based guidelines for mixed afforestation establishment in South China.
Methods We designed a pot experiment consisting of three treatments to evaluate effects of competion on seedling growth and foraging behavior of P. massoniana and S. superba. The treatments were single-, pure- and mixed-plantings under heterogeneous and homogeneous environments.
Important findings Compared with the homogeneous nutrient envionment, seedlings in the heterogeneous nutrient environment were taller, had greater dry matter accumulation and had more effective nutrient absorption with increased root proliferation in the nutrient-rich patches. In the heterogeneous environment, S. superba had better growth in mixed- than in single- and pure-plantings, and exhibited enhancement of root morphological and physiological plasticity in foraging patchy nutrients. Pinus massoniana in the mixed-planting also was taller, not only because of little change of root scale, sensitivity and precision but also increased nutrient absorption efficiency. However, intraspecific competition reduced root scale, sensitivity and root N, and P content and resulted in significantly decreased seedling height and dry matter accumulation. Schima superba was affected more markedly by intraspecific competition than P. massoniana in the heterogeneous environment. It is suggested that mixed-plantings can improve the growth of P. massoniana and S. superba and appropriate decrease of initial density or timely control of stand density can increase the productivity of pure plantations of the two species.

Key words: Pinus massoniana, Schima superba, heterogeneous nutrient environment, competition, foraging behavior