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间伐对马尾松人工林土壤活性氮组分的影响
马婷瑶1,2, 翟凯燕1,2, 金雪梅,等1,2
1.南方现代林业协同创新中心;2.南京林业大学 生物与环境学院
摘要:
【目的】研究实施不同强度间伐后的马尾松(Pinus massoniana Lamb.)人工林土壤活性氮组分在各季节的变化规律,以明晰间伐对土壤活性氮的影响程度,为确定适宜的间伐强度及森林土壤氮素管理提供科学依据。【方法】以南京市溧水区林场2006年实施不同强度(弱度25%,中度45%,强度65%)间伐的29年生马尾松人工林为研究对象,以未间伐为对照,于2015年4,7,10,12月采集不同处理0~10和10~20 cm土层土样,测定不同土层4种活性氮组分(可溶性有机氮(DON)、微生物生物量氮(MBN)、铵态氮(NH+4-N)、硝态氮(NO-3-N))的含量,分析不同间伐强度对土壤活性氮组分的影响。【结果】各活性氮组分含量存在一定的季节差异性,DON、MBN和NO-3-N含量在夏季均较低,NH+4-N含量在夏季和秋季时较高。活性氮组分对间伐的响应存在一定的季节差异。与对照样地相比,各间伐强度显著(P<0.05)降低了春季和冬季土壤的DON含量,提高了夏季和秋季土壤的DON含量。弱度和中度间伐显著(P<0.05)提高了各季节土壤MBN含量;强度间伐显著(P<0.05)提高了春季和冬季土壤MBN含量,降低了夏季和秋季土壤MBN含量。各间伐强度显著(P<0.05)提高了春季和夏季土壤的NH+4-N含量,降低了秋季土壤的NH+4-N含量;对冬季土壤NH+4-N含量的影响不一致,弱度间伐显著(P<0.05)升高,中度间伐显著(P<0.05)降低,强度间伐影响不显著。与对照样地相比,弱度和中度间伐显著(P<0.05)增加了春季土壤NO-3-N含量,降低了秋冬季土壤NO-3-N含量,弱度间伐对夏季土壤的NO-3-N含量无显著影响,中度间伐显著(P<0.05)提高夏季土壤NO-3-NN含量;强度间伐显著(P<0.05)提高春季土壤NO-3-N含量,降低夏季和冬季土壤的NO-3-N含量,对秋季土壤NO-3-N含量无显著影响。【结论】各间伐强度对土壤活性氮组分的含量均有一定影响,中度间伐可促进土壤活性氮组分的有效利用,为提高土壤氮素有效性,以实施中度间伐为宜。
关键词:  间伐  马尾松人工林  活性氮组分  季节变化
DOI:
分类号:
基金项目:国家重点基础研究发展计划(“973”计划)子专题(2012CB416904)
Effects of thinning on soil active nitrogen in Masson pine plantation
MA Tingyao,ZHAI Kaiyan,JIN Xuemei,et al
Abstract:
【Objective】To clarify the effects of thinning on soil activity nitrogen,and provide scientific basis for thinning and soil nitrogen managements in forests,this paper studied the seasonal variations of soil active nitrogen contents under different thinning intensities in a Masson pine (Pinus massoniana Lamb.) plantation.【Method】The study was conducted in a 29 a Masson pine plantation thinned by three intensities (light thinning:25% tree removal,moderate thinning:45%,and high thinning:65%) in 2006 in the Lishui Forest Farm of Nanjing.The soil samples were collected at layers of 0-10 and 10-20 cm in April,July,October,and December in 2015,and the contents of four soil active nitrogen components (dissolved organic nitrogen DON,microbial biomass nitrogen-MBN,ammonium nitrogen NH+4-N,and nitrate nitrogen NO-3-N) were determined.The effects of thinning intensities on soil active nitrogen were analyzed using un thinned stand as control. 【Result】 Active nitrogen contents showed seasonal variations.Soil DON,MBN and NO-3-N contents were low in summer while NH+4-N was high in summer and autumn.The responses of active nitrogen components to thinning intensity also changed with seasons.As compared to the control,thinning significantly (P<0.05) reduced soil DON content in spring and winter,while increased it in summer and autumn.Light and moderate thinning significantly (P<0.05) enhanced soil MBN content.High thinning significantly (P<0.05) increased soil MBN content in spring and winter, but reduced it in summer and autumn.Thinning significantly raised soil NH+4-N content in spring and summer,reduced it in autumn,but showed divergent effects in winter (light thinning had positive effect,moderate thinning had negative effect,while high thinning appeared to be neutral).As compared to the control, light and moderate thinning significantly increased soil NO-3-N content in spring and reduced it in autumn.Light thinning had no effect while moderate thinning had significantly positive effects on NO-3-N content in summer.High thinning significantly increased NO-3-N content in spring,reduced it in summer and winter,but had no effect in autumn.【Conclusion】 All thinning intensities had effects on soil active nitrogen contents,and moderate thinning improved the soil active nitrogen use efficiency.Therefore,it would be appropriate to employ moderate thinning to improve soil nitrogen status.
Key words:  thinning  Masson pine plantation  active nitrogen  seasonal changes