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以现有11年生马尾松(Pinus massoniana)人工林为基础,通过均匀间伐、抚育修枝,结合冠层分析仪(CI-110)测定郁闭度,形成林冠郁闭度约为0.9、0.8、0.7、0.6、0.5的5个梯度系列样地,研究马尾松叶片碳(C)、氮(N)、磷(P)养分含量、养分再吸收率及化学计量特征.结果显示:1)随林冠郁闭度减小,叶片N含量、C:N、N:P皆存在显著差异,叶片C含量、P含量、C:P都没有显著差异;C含量、N含量、C:N、N:P皆呈抛物线趋势;C含量在0.6郁闭度时最大,N含量、N:P在0.7郁闭度时最大,C:N在0.7郁闭度时最小.N:P在11.15-16.38之间,说明该研究区的马尾松生长同时受N、P限制.2)随林冠郁闭度减小,N养分再吸收率、N与P养分再吸收率之比都存在显著差异,P养分再吸收率没有显著差异;N、P养分再吸收率皆呈抛物线趋势,且都在0.7郁闭度时最大.3)不同林冠郁闭度马尾松叶片C:N:P化学计量比与N养分再吸收率、P养分再吸收率、N与P养分再吸收率之比都存在极强的相关性关系.4)随林冠郁闭度处理时间的延长,土壤p H值都有所升高,土壤含水量和土壤全N累积量有所下降,土壤有机碳累积量在3个中等林冠郁闭度下有所降低,土壤全P累积量在低林冠郁闭度时有所升高,而在0.7中等林冠郁闭度下有所降低.5)不同年份间马尾松叶片C:N:P及其N与P养分再吸收率之比皆在林冠郁闭度0.7时较为稳定.本研究表明林冠郁闭度为0.7的马尾松人工林林内微环境为马尾松的快速生长、良好发育提供了最为适宜的环境,具有较高的化学计量比内稳性.
Based on the current 11-year-old Pinus massoniana plantation, canopy density was determined by uniform thinning, tending and pruning, and canopy analysis (CI-110) (C), nitrogen (N) and phosphorus (P), nutrient reabsorption rate and stoichiometry were studied in five gradient series with 0.7, 0.6, 0.5.The results showed that: 1) C content, N content, C: N, N: P, there were significant differences in leaf C content, P content, C: P content, All showed a parabola trend; the content of C was the largest at 0.6 canopy closure, the N content was the largest at 0.7 canopy closure and the smallest was C: N at 0.7 canopy closure. The N: P was between 11.15-16.38, The results showed that the growth of Pinus massoniana in the study area was limited by N and P. 2) With the decrease of canopy density, N nutrient re-absorption rate and N and P nutrient re-absorption ratio were significantly different, P nutrient re-absorption rate There was no significant difference in N and P nutrient reabsorption rates with parabolic trend, both of which were the largest at 0.7 canopy degree.3) C: N: P stoichiometry and N nutrient reabsorption rate of Pinus massoniana leaves with different crown canopy degrees P nutrient absorption Yield, N and P nutrient re-absorption ratio of the relationship there is a strong correlation.4) With canopy crown treatment time extension, soil p H values have increased, soil moisture and soil N The cumulative amount of soil organic carbon decreased at three canopy canopy closures, and soil total P accumulation increased at low crown canopy closures, while at 0.7 canopy crown closures Decreased.5) The ratio of C: N: P and its N and P nutrient reabsorption rate of Pinus massoniana in different years were more stable at the canopy closure degree of 0.7.The present study shows that the canopy density of the crown canopy is 0.7 The microenvironment of Pinus tabulaeformis plantation provides the most suitable environment for the rapid growth and good development of Pinus massoniana and has high stoichiometry internal stability.