南方红豆杉人工林针叶C、N、P化学计量特征

【目的】 研究南方红豆杉人工林针叶C、N、P生态化学计量和养分重吸收特征,揭示南方红豆杉的养分限制格局和养分高效利用策略,为南方红豆杉人工林的高质量种植栽培提供理论依据。【方法】 以9年生南方红豆杉人工林为研究对象,通过测定其针叶碳(C)、氮(N)、磷(P)元素含量,分析针叶的生态化学计量、养分重吸收率及其相互关系。【结果】 南方红豆杉针叶C、N、P平均含量分别为479.67、22.52和2.21 g/kg,碳氮质量比(C:N)、碳磷质量比(C:P)、氮磷质量比(N:P)分别为21.74、226.25和10.55;N与P、C含量均呈极显著正相关,P与C含量呈显著正相关;生长季中,南方红豆杉针叶C含量最稳定,变异系数为3.90%,P含量的变异系数(22.43%)大于N(15.34%)。研究区南方红豆杉在生长季(6—11月)针叶C与N含量均表现为先平缓上升后显著下降趋势,8月达到高峰并持续到9月,C含量10月最低,N含量11月最低;P含量则表现为先显著上升后显著下降的趋势,在9月达到峰值,且显著大于其他各月份;针叶中C:N和N:P的变化比C:P更稳定,且P含量决定了C:P和N:P的动态变化。南方红豆杉针叶N重吸收率和P重吸收率分别为19.33%和22.16%,且P重吸收率与衰老叶P含量、C:P呈显著负相关,与N:P呈显著正相关。【结论】 研究区内,9年生南方红豆杉人工林针叶具备较好的C储存能力和养分资源竞争力,N、P重吸收率较低,养分在针叶中的驻留时间较长,生长未受到N、P限制。

Stoichiometric characteristics of C,N, P of Taxus chinensis var. mairei plantation needles

【Objective】 The nutrient ecological stoichiometry and nutrient reabsorption characteristics of Taxus chinensis var. mairei needles were studied to reveal its nutrient restriction pattern and nutrient efficient utilization strategy, thereby providing a theoretical basis for its high-quality afforestation and plantation cultivation 【Method】 The nutrient contents, ecological stoichiometric ratio, nutrient reabsorption efficiency and their relationships were analyzed by measuring the contents of carbon (C), nitrogen (N), and phosphorus (P) and their stoichiometric characteristics in needles of 9-year-old T. chinensis var. mairei plantations at different growth stages. 【Result】 The results showed that the average C, N and P contents of T. chinensis var. mairei plantation needles were 479.67, 22.52 and 2.21 g/kg, respectively. The C/N mass ratio (C:N), C/P mass ratio (C:P), and N/P mass ratio (N:P) were 21.74, 226.25 and 10.55, respectively. A significantly positive correlation between N, P and C existed. Similarly, P content was significantly positively correlated with C content. The C content, which was stable in the needles, had a lower coefficient of variation (3.09%), and P (22.43%) content had higher variability than that of N (15.34%). During the growing season (from June to November), the contents of C and P first rose slightly, and decreased dramatically,both peaked in August and kept until September. The C and N contents reached the lowest in October and November, respectively. The P content increased obviously first, then declined greatly,and peaked in September,much higher than those in other months. Changes in C:N and N:P were stabler than those in C:P that relied on P content. The nitrogen reabsorption efficiency (NRE) and phosphorus reabsorption efficiency (PRE) were 19.33% and 22.16%, respectively. The PRE was negatively correlated with P content and C:P in the senescent needles, but positively correlated with N:P. 【Conclusion】 In the study area, needles of 9-year-old T. chinensis var. mairei plantations had a good C storage capacity and nutrient resource competitiveness, and the nutrients were retained long time in needles because of the low efficiency of N and P reabsorption. Therefore, growth and development of T. chinensis var. mairei plantations was not hindered by N and P.