Fujian Outstanding Youth Rolling Grant Project (2014J07005)
为探究马尾松和杉木人工林细根碳(C)、氮(N)、磷(P)浓度及其化学计量比随土层深度变化的特征,于2011年4月在福建省三明市金丝湾森林公园陈大林业采育场内测定马尾松和杉木人工林五个土层深度(0-10 cm、10-20 cm、20-40 cm、40-60 cm、60-80 cm)细根的C、N、P浓度、比根长(SRL)及其土壤养分浓度,结果表明:林分类型显著影响细根C浓度,但对细根N、P浓度无显著影响,马尾松人工林细根C浓度显著大于杉木人工林。土层深度显著影响马尾松和杉木人工林细根N、P浓度,对C浓度无影响,细根N、P浓度随土壤深度的增加呈指数下降。马尾松和杉木人工林细根N、P浓度与土壤全氮(TN)、全磷(TP)浓度以及SRL均呈正相关。拟合直线表明马尾松人工林和杉木人工林细根N养分获取能力的不同,马尾松对N养分的获取能力更强,而杉木通过SRL获取养分的能力比马尾松更强,可能体现了两种人工林细根N获取策略的差异。马尾松和杉木人工林在不同土层细根N ∶ P比值(33.5±2.81、30.18±2.10)均大于16,表明两者均受P限制,但细根N ∶ P不受土壤N ∶ P和SRL的影响。马尾松和杉木人工林细根N和P浓度受土层深度的影响,与土壤养分和细根形态特征变化有关。
In order to examine the characteristics of fine root carbon (C), nitrogen (N), and phosphorus (P) concentrations and their stoichiometric ratios changing with soil depth in Masson pine (Pinus massoniana) and Chinese fir (Cunninghamia lanceolata) plantations, the experiments were conducted in April 2011, in Jinsiwan Forest Park, Sanming City, Fujian Province. The samples of fine roots in five soil depths (0-10 cm, 10-20 cm, 20-40 cm, 40-60 cm, 60-80 cm) of Masson pine and Chinese fir plantations were collected in the big forestry breeding farm to determine C, N and P concentration as well as specific root length (SRL). Soil nutrient contents were also measured. The results showed that forest type significantly influenced fine root C concentration, but not fine root N and P concentration, and that fine root C concentration was significantly greater in the plantation of Masson pine than in the plantation of Chinese fir. Soil depth significantly influenced fine root N and P concentrations, but not C concentrations, and fine root N and P concentrations decreased exponentially with increasing soil depth in both pinus sylvestris and fir plantations. Fine root N and P concentrations were positively correlated with soil Total nitrogen (TN) and Total phosphorus (TP) concentrations as well as SRL in both Horsetail Pine and Fir plantations. The fitted straight lines indicated the difference in the fine root N nutrient acquisition capacity between horsetail pine and fir plantations, with horsetail pine having a greater ability to acquire N nutrients and fir having a greater ability to acquire nutrients through SRL than horsetail pine, possibly reflecting the difference in fine root N acquisition strategies between the two plantations. The fine root N ∶ P ratios (33.5±2.81 and 30.18±2.10) of both horsetail pine and fir plantations were greater than 16 in different soil layers, indicating that both were P-limited, but fine root N ∶ P was not influenced by soil N ∶ P and SRL. Fine root N and P concentrations in plantations of horsetail pine and fir were influenced by soil depth and were related to changes in soil nutrients and fine root morphological characteristics.