Conservative changes in ecosystem C:N:P stoichiometry are mediated by plant diversity and tree size along a forest succession chronosequence

Ecosystem C:N:P stoichiometry has implications for biogeochemical cycles and ecosystem functioning. However, variations in ecosystem stoichiometry along a forest succession chronosequence and the underlying mechanisms remain unclear. We quantified the C:N:P stoichiometry of different plant organs (leaves, branches, stems and roots), and different ecosystem components (plant community, litter and soil) at four successional stages of a mixed broadleaved–Korean pine ( Pinus koraiensis ) forest in northeast China. The C:N:P stoichiometry of plant organs and the plant community varied significantly along the succession chronosequence, with variation mainly driven by changes in tree size and plant diversity. The C:N:P stoichiometry in litter and soil did not change with succession. Furthermore, most allometric exponents of C-N-P scaling relationships did not differ among plant organs and ecosystem components and were equal to 1, indicating strong conservatism of the C-N-P stoichiometry scaling relationship in this ecosystem. Our findings highlight the conservative isometric allocation strategies of elements among different organs and ecosystem components during forest succession. Further, they help improve our understanding of the underlying mechanisms for variations in C:N:P stoichiometry from the plant organ level to the ecosystem level.