带状采伐毛竹林养分动态特征

Dynamic characteristics of nutrients in striped cutting Moso bamboo forests

【目的】研究带状采伐毛竹林中氮、磷、钾养分变化特征,为伐后竹林的养分管理策略提供科学依据。【方法】以8 m带宽采伐样地(SC)及其保留样地(RB)为研究对象,以传统经营毛竹林(CK)为对照,调查伐后5年内不同处理样地毛竹生物量、林下灌草生物量、凋落物产量及各组分相应的养分含量,量化养分流通量,计算不同处理样地的养分循环系数,比较不同处理样地的养分流动及循环特征的差异。【结果】(1)伐后第1年,不同处理样地内毛竹氮、磷、钾的留存量无显著差异;采伐样地中氮、磷的归还量减少;(2)伐后3年,保留样地中氮、磷、钾的留存量小于采伐样地和对照样地;采伐样地和保留样地中氮的归还量显著低于对照样地。(3)伐后5年,保留样地中氮的留存量小于采伐样地和对照样地;采伐样地中氮、磷、钾的归还量、养分贮量均与对照样地无显著差异;(4)带状采伐显著增加了氮、磷的利用系数(P<0.05),随着样地的恢复各养分的利用系数逐渐下降,与对照无差异;采伐对氮、磷、钾的循环系数无显著影响。【结论】伐后5年氮、磷、钾养分贮量达到伐前和现期对照样地水平,从养分循环的角度证明伐后5年带状采伐样地能够恢复到对照样地水平。保留样地养分利用系数和循环系数从伐后第二个大年开始逐渐降低,需要进行密度调控,从而提高养分利用效率。

[Objective]This paper aims to study the dynamics of nitrogen(N),phosphorus(P),and potassium(K)nutrients in Moso bamboo forest after strip cutting,so as to provide a scientific basis for nutrient management strategies in the amboo forest after logging.[Method]We selected the 8 m bandwidth strip cutting sample plots(SC)and its reserved sample plots(RB)as the research object,and the traditional management forest(CK)as control.The biomass of Moso bamboo,understory vegetation,litter yield,and corresponding nutrient contents of each component was investigated for five years after cutting.Therefore,nutrient flux was quantified,and the nutrient cycling coefficient of the Moso bamboo forest was calculated.The characteristics of nutrient flow and cycling were compared among different treatment sample plots.[Result](1)In the first year after cutting,there was no significant difference in the retention of N,P,and K among different treatment sample plots.The return of nitrogen in SC was decreased.(2)Three years after cutting,the retention of N,P,and K in the RB was less than that in SC and CK.The return of nitrogen in SC and RB was significantly lower than that in CK.(3)Five years after cutting,the retention of nitrogen in RB was less than that in SC and CK.There was no significant difference in the amount of N,P and K returned and nutrient storage between SC and CK.(4)Strip cutting significantly increased the utilization coefficients of N,P(P<0.05).With the restoration of sample plots,the utilization coefficient of each nutrient gradually decreased,and there was no difference with CK.Cutting had no significant effect on the cycling coefficients of N,P and K.[Conclusion]Five years after cutting,nitrogen,phosphorus,and potassium nutrient storage reaches the level of pre-cutting and CK.From the perspective of nutrient cycle,it is proved that SC could recover to the level of CK after 5 years.However,the nutrient use coefficient and recycling coefficient of RB gradually decrease from the second on-year after cutting,and density control management is needed to improve the nutrient use efficiency.