Provenance variation of root C, N, P, and K stoichiometric characteristics under different diameter classes of Larix gmelinii.

ABSTRACT

For exploring the difference of root stoichiometric characteristics among diameter classes and provenances, we examined the contents and stoichiometric ratios of carbon (C), nitrogen (N), phosphorus (P), and potassium (K) in three diameter classes of roots (0-1, 1-2 and 2-5 mm, respectively) of 39-year-old Larix gmelinii grown in a common garden. The results showed that root element contents and their stoichiometric ratios had significant difference among three diameter classes of roots. C content, CN, CP, CK were the lowest, and N, P, K contents, NP, and NK were the highest in 0-1 mm diameter class roots. Compared with the 1-2 and 2-5 mm diameter class roots, 0-1 mm diameter class roots had different seasonal dynamics, which might be caused by the fact that 0-1 mm diameter class roots are absorptive roots and the other diameter class roots are transport roots. There was no provenance difference in C content among all diameter class roots, while significant provenance differences were found in N, K contents, CN, and CK in 0-1 mm diameter class roots, and great provenance differences for in P content, CP, NP, and NK in 0-1 and 1-2 mm diameter class roots. N content, K content, CP, NP, and NK in 0-1 mm diameter class roots had positive correlation with the aridity index of seed-source sites, while the P content, CN and CK had negative correlations. The stoichiometric characteristics were related with the diameter (or function) of roots, and had significant provenance differences in 0-1 mm (absorptive root) and 1-2 mm diameter class roots, which might be attributed to their genotypic adaptation to the environment of seed-source sites.