兴安落叶松不同径级根碳氮磷钾化学计量特征的种源差异

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

为了深入认识树木根化学计量特征的径级差异和种源差异,对生长在同质园内6个种源39年生兴安落叶松不同径级根(根直径为0~1、1~2和2~5 mm)的碳(C)、氮(N)、磷(P)、钾(K)含量及其计量比进行了研究。结果表明:兴安落叶松根C、N、P、K含量及其计量比均存在显著的径级差异,0~1 mm径级根具有最小的C含量、C∶N、C∶P、C∶K,以及最大的N、P、K含量和N∶P、N∶K,且与1~2和2~5 mm 2个径级根具有不同的季节动态,这种差异与0~1 mm径级根是吸收根而其他径级根为运输根有关。各径级根C含量种源差异不显著,N和K含量及C∶N和C∶K均在0~1 mm径级根中存在显著的种源差异,P含量及C∶P、N∶P、N∶K在0~1和1~2 mm 2个径级根中均存在显著的种源差异。0~1 mm径级根N、K含量及C∶P、N∶P、N∶K均与种源原地干燥度呈显著正相关,P含量、C∶N和C∶K均与种源原地干燥度呈显著负相关。根化学计量特征因径级(功能)的不同而产生差异,其中仅0~1(吸收根)和1~2 mm径级根的部分化学计量特征存在种源差异,这可能是对当地种源原地环境长期适应的结果。

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,C:N,C:P,C:K were the lowest,and N,P,K contents,N:P,and N:K 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,C:N,and C:K in 0-1 mm diameter class roots,and great provenance differences for in P content,C:P,N:P,and N:K in 0-1 and 1-2 mm diameter class roots.N content,K content,C:P,N:P,and N:K in 0-1 mm diameter class roots had positive correlation with the aridity index of seed⁃source sites,while the P content,C:N and C:K 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.