关键词: 氮磷添加, 林分类型, 化学计量特征, 养分重吸收, 刨花楠

Abstract: Clarifying the ecological stoichiometry of “leaf-litter-soil” continuum of Machulus pauhoi under the influence of nitrogen (N) and phosphorus (P) addition can provide scientific basis for revealing the nutrient limitations and adaptation strategies of M. pauhoi plantations. A four-year experiment was conducted with control (CT), N addition (+N), P addition (+P), and co-addition of N and P (+NP) to investigate the effects of N and P addition on C, N, and P concentrations and their stoichiometric characteristics of leaf, leaf litter, and soil of M. pauhoi in a pure plantation of M. pauhoi and a mixed plantation of M. pauhoi and Cunninghamia lanceolata. The results showed that: (1) +N significantly affected leaf litter P concentration and C∶P in pure stand, and soil P concentration and its C∶P of mixed stand. +P significantly affected leaf litter N and P concentration of pure stand, and leaf N concentration and C∶N of mixed stand. +NP significantly affected leaf litter N and P concentration, C∶N, and C∶P of pure stand, as well as leaf litter C and N concentration and soil P concentration and its N∶P and C∶P of mixed stand (P<0.05). (2) Compared with the pure stand, +N significantly affected leaf N concentration and C∶N of M. pauhoi, and soil N concentration, C∶N, and N∶P. +P significantly affected leaf litter P concentration and its C∶P, and soil N concentration and C∶N. +NP significantly affected leaf N concentration, leaf litter N concentration, C∶N and N∶P, and soil N concentration, C∶N, and N∶P in the mixed stand (P<0.05). (3) +P and +NP increased N resorption efficiency in pure stand and decreased that in mixed stand, while +N improved P resorption efficiency in pure stand. This result indicated that mixed stand may be more effective in N use, while the N-limitation in pure stand was stronger than that of mixed stand. Young forest of M. pauhoi was jointly limited by N and P in the study area. (4) The relationships between leaf-litter-soil nutrients and stoichiometric ratios were significantly affected by stand type. Specifically, the correlation between fresh leaf and leaf litter was stronger in pure stand, but the correlation between leaf litter and soil was relatively weak in mixed forest. Collectively, this study revealed the effects of N and P addition on the ecological stoichiometry characteristics of the “leaf-litter-soil” continuum in different stand types of M. pauhoi, providing an important theoretical basis for the efficient management of M. pauhoi plantations, as well as the nutrient management.

Key words: nitrogen and phosphorus addition, stand type, stoichiometric characteristics, nutrient resorption, Machilus pauhoi