摘要
以江苏省泗洪县陈圩林场5年生的具有不同混交比例的南林95杨(Populus×euramericana‘Nanlin-95’)和江南桤木(Alnus trabeculosa)混交林为对象,对混交5年后所产生的林地局部土壤养分异质性以及碳、氮、磷生态化学计量特征进行研究,从养分供应和平衡角度探讨引入固氮树种进行混交后在短期内所产生的混交效应,为杨树人工林养分管理及杨树混交林营造提供理论依据。研究结果表明,杨-桤混交5年整体上提高了林地土壤p H值,但其提高程度随桤木比例的增加而下降。杨-桤2∶1混交林分中由杨树与桤木围成的行间0~10 cm土层的土壤pH值为6.98,显著低于由2行杨树所围成的区域(7.29),表现出明显的异质性。土壤有机碳和全氮含量在各种混交比例林分的不同区域变化不大,而全磷含量则表现为混交林分略高于杨树纯林。4种混交比例林分土壤中硝态氮占无机氮总量的98%以上,同一混交林分中靠近桤木行区域的0~10cm土层土壤的铵态氮含量整体上高于靠近杨树行的区域,其中杨-桤1∶2混交林分中由2行桤木所围成的区域的0~10 cm土层土壤铵态氮含量(0.60 mg·kg^(-1))是杨树纯林的2.14倍。杨-桤2∶1混交林分中由杨树与桤木围成的区域0~10 cm土层土壤C∶N比(9.48)和C∶P比(29.13)均显著低于杨树纯林(分别为12.46和39.64),反映了混交引起的林地养分提高效应以及生态化学计量学特征的改变。整体而言,固氮树种桤木的引入在混交5年后即导致混交林地土壤出现一定程度的养分异质性,提高了林地局部区域的土壤养分含量、供应能力,并改变了其生态化学计量学特征。
Serious site degradation appears in poplar plantations due to continuous rotations with single poplar tree species.Establishment of mixed plantation with N-fixing tree species is considered to be an effect way to resolve this problem,while its short-term effects were not clear after the establishment.In order to reveal the effects of mixed poplar plantation with N-fixing tree species on soil nutrients properties after short-term establishment,four 5-year-old plantations with different mixing ratios of poplar(Populus×euramericana‘Nanlin-95’)and alder(Alnus trabeculosa)in Chenwei forest farm,Sihong,Jiangsu Province,were used to investigate the heterogeneity of soil nutrient contents and C∶N∶P ecological stoichiometry.The results indicated that soil pH increased in all mixed poplar-alder plantations after 5 years when compared with the pure poplar plantation,while the increasing extent reduced with the increased mixing ratio of alder.In the plantation with a mixing ratio of poplar and alder as 2∶1,obvious heterogeneity was detected for the pH of 0~10 cm soil layer,which was significantly lower in the area surrounded by the tree lines of poplar and alder,with mean value as 6.98,than in that surrounded by two lines of poplar,with mean value as 7.29.No significant differences were found for the contents of soil organic C and total N in either different plantations or in different areas of each plantation.The content of soil total P was slightly higher in the mixed plantations than in the pure poplar plantation.Nitrate-N occupied more than 98%of soil inorganic N.Ammonium-N showed less dominance in the 0~10 cm soil layer,while it was generally higher in the area near the alder line than the area near the poplar line in the same mixed plantation.Especially in the plantation with a mixing ratio of poplar and alder as 1∶2,the content of NH4+-N was 2.14-time higher in the area surrounded by two lines of alder than in pure poplar plantation.The C∶N ratio and C∶P ratio of the 0~10 cm soil layer were significantly lower in the area surrounded by the tree lines of poplar and alder in the plantation with a mixing ratio of poplar and alder as 2∶1 than in pure poplar plantation,which showed obvious changes of soil C∶N∶P ecological stoichiometry after short-term mixing with alder,and indicated the beneficial effect on soil nutrient supply.Based on the results above,obvious heterogeneity of soil nutrients was proved after 5 years of the introducing of N-fixing tree species into the poplar plantation,which might have potential improvement for the growth of poplar.
作者
张贾宇
徐叶宁
陶慧颖
鄂晓伟
田野
唐罗忠
ZHANG Jiayu;XU Yening;TAO Huiying;E Xiaowei;TIAN Ye;TANG Luozhong(College of Forestry,Co-Innovation Center for Sustainable Forestry in Southern China,Nanjing Forestry University,Nanjing 210037,China)
出处
《生态环境学报》
CSCD
北大核心
2018年第2期216-223,共8页
Ecology and Environmental Sciences
基金
国家科技支撑计划课题(2015BAD09B02)；国家自然科学基金项目(31370618)；国家重点研发计划课题(2016YFD0600402)
关键词
杨树人工林
混交
养分异质性
生态化学计量
短期效应
poplar plantation
tree mixing
nutrient heterogeneity
ecological stoichiometry
short-term effect
