修枝与施肥对云南松生长、针叶性状和养分的影响

Effects of pruning and fertilization on growth,needle traits and nutrients of Pinus yunnanensis

【目的】分析修枝和施肥的不同水平对云南松生长与针叶性状及其N、P和K含量的影响,为云南松用材林高效培育提供修枝和施肥的实践依据和技术支撑。【方法】采用L_(9)(3^(4))正交设计开展修枝强度、肥料种类及其施肥量的试验,于第一次(修枝和施肥)和第二次(仅施肥)试验开展1 a后测定林木生长、针叶性状及其氮(N)、磷(P)和钾(K)含量,分析两次试验对测定指标的影响。【结果】第二次施肥后1 a时,处理组合目标树的胸径、树高和材积增长率较第一次试验后分别达10.2%~15.6%、9.9%~22.5%和33.0%~45.9%。除胸径外,均极显著地高于对照的10.2%、8.4%和28.5%(P<0.01)。针叶长及百束松针生物量较第一次分别提高8.8%~16.3%和10.4%~18.0%,亦极显著地高于对照的5.6%和8.0%(P<0.01)。针叶N、P和K分别较第一次试验1 a后提高36.8%~118.4%、58.1%~187.9%和63.1%~159.4%(对照的13.6%、17.9%和59.8%)。两次测定m(N)∶m(P)为9.3∶1~12.4∶1和7.4∶1~9.8∶1,分别低于对照的10.4∶1和10.0∶1。影响胸径、树高和材积生长的主导因子均为修枝强度和肥料种类的交互作用,影响针叶长与生物量及N的主导因子为肥料种类,P和K的则为修枝强度。试验实施2 a后,云南松针叶的m(N)∶m(P)<14,研究区林木主要受N养分限制,目标树生长速率随N和P化学元素计量比的变化而加快,并实现新的动态平衡。【结论】综合目标树生长和针叶特征变化,云南松人工林适宜的修枝和施肥措施为保留5轮枝条,每5 cm胸径施复合肥[m(N)∶m(P)∶m(K)=12∶10∶24,总养分>46%)]0.4 kg。

【Objective】The research is to understand the effects of different levels and their treatment combinations(TCs)of pruning and fertilization on the forest growth rate involved in needle traits and leaf N,P and K contents of objective trees(OT)in a middle-aged Pinus yunnanensis plantation in order to provide practical basis and technical support of combined pruning and fertilization for efficient cultivation of P.yunnanensis timber forest.【Method】The L_(9)(3^(4)) orthogonal design was employed to implement the trial of pruning intensity,fertilizer types and fertilizer amount.One year after the first(pruning and fertilizing)and the second(fertilizing only)trial,the growth indicators,needle traits and contents of nitrogen(N),phosphorus(P)and potassium(K)were measured to analyze the effects of the two trials test indicators.【Result】One year after the second fertilization,the growth rates of diameters at breast height(DBHs),tree heights(THs)and timber volumes(TVs)for the TCs of the OTs were 10.2%-15.6%,9.9%-22.5%and 33.0%-45.9%,respectively,compared to those of the first trial.Except for the DBHs,the above parameters were significantly higher than 10.2%,8.4%and 28.5%of the control(P<0.01).Needle length and biomass of 100-bunch needle increased by 8.8%-16.3%and 10.4%-18.0%,respectively,compared to that of the first trial,which were also significantly higher than those of the control(5.6%and 8.0%;P<0.01).The N,P and K contents of needles increased by 36.8%-118.4%,58.1%-187.9%and 63.1%-159.4%(13.6%,17.9%and 59.8%of the control),respectively,compared to those of the first trial.The N∶P of the needle for the two measurements were 9.3∶1-12.4∶1 and 7.4∶1-9.8∶1,which were lower than 10.4∶1 and 10.0∶1 of the control,respectively.The dominant factors affecting the DBHs,THs and TVs were the interaction of pruning and fertilizer amount,while needle length,biomass and the content of N were primarily influenced by fertilizer type,and the contents of P and K were mainly affected by pruning intensity.Two years after the trial was implemented,the m(N)∶m(P)of P.yunnanensis needle was lower than 14.The N nutrient was the factor limiting tree growth in the study area,and the OT growth rate of P.yunnanensis was accelerated with the change of stoichiometric ratio of N and P chemical elements,then a new dynamic equilibrium was achieved.【Conclusion】Considering the changes of OT growth and needle characteristics,the appropriate combination of pruning and fertilization measures was retaining 5 rounds of branches and applying compound fertilizer m(N)∶m(P)∶m(K)=12∶10∶24,total nutrient>46%)0.4 kg for per 5 cm DBH.