刺槐与其他树种枯落叶混合分解对微量元素释放的影响

【目的】检测刺槐分别与其他10个树种枯落叶混合分解后是否对Cu、Zn、Ni和Cd等微量元素的释放产生促进作用，从微量元素的角度研究刺槐与拟混交树种的种间养分关系，为刺槐混交林的树种选择提供科学依据。【方法】在黄土高原，于秋末冬初采集刺槐及其他10个树种的当年枯落叶，并剪成1 cm大小的碎片或长1 cm的短针叶，同时采集无林荒草地腐殖质层（0～20 cm）土壤作为介质，在室内相同温度和湿度条件下，以尼龙网袋埋土法连续345 d进行枯落叶混合分解培养试验，并用原子吸收光谱分析法（AAS）测定枯落叶分解前后微量元素Cu、Zn、Ni、Cd的含量。【结果】枯落叶分解过程中，Cu、Zn、Ni和Cd的释放速率均以柠条、小叶杨、沙棘、侧柏、辽东栎较快，周转期略大于1年。刺槐分别与小叶杨、白榆、沙棘枯落叶混合分解，对4种微量元素的释放均呈现出促进作用；而分别与樟子松、侧柏、白桦、柠条枯落叶混合分解，对4种微量元素的释放均呈现出抑制作用；刺槐分别与油松、华北落叶松枯落叶混合分解，对Cu的释放有一定的促进作用，而对Zn、Ni、Cd的释放呈现出抑制作用；刺槐与辽东栎枯落叶混合分解，对Zn、Cd的释放有促进作用，而对Cu、Ni的释放有抑制作用。【结论】选择与刺槐枯落叶混合分解后能促进多数微量元素释放的树种进行混交，将有利于林地微量元素的循环利用。

Influences of mixed leaf litter decomposition of Robinia pseudoacacia with other trees on microelements release

【Objective】From the standpoint of microelements,the interspecific nutrient relationship of Robinia pseudoacacia with other trees were studied through detecting whether the mixed leaf litter decomposition of R.pseudoacacia with other trees would produce promoted or inhibitory actions on release of Cu,Zn,Ni and Cd,in order to provide a scientific basis for selection of tree species mixed with R.pseudoacacia.【Method】In the whole Loess Plateau,through collecting leaf litter of R.pseudoacacia and other 10 trees at the end of autumn,cutting the leaf to some fragments(φ=1 cm) or 1 cm needles,and gathering humus soil(0-20 cm) of no forested land as medium,the incubation of mixed leaf litter decomposition had been carried out for 345 d with the method of nylon mesh bag buried with soil in the same condition of temperature and moisture.Then,the microelements(Cu,Zn,Ni,Cd) contents before and after leaf litter decomposition were determinated with the Atomic Absorption Spectroscopy(AAS)method.【Result】The release rates of Cu,Zn,Ni and Cd during unique leaf litter decomposition of Populus simonii,Hippophae rhamnoides,Platycladus orientalis and Quercus liaotungensis are all the fastest and the turnover period is 1 year or a little more.Mixing litter decomposition of R.pseudoacacia with P.simonii,Ulmus pumila,H.rhamnoides separately would produce promoted actions on release of the microelements,whereas mixed litter decomposition of R.pseudoacacia with Pinus sylvestris var.mongolica,P.orientalis,Betula platyphylla and Caragana microphylla separately would produce inhibitory actions on release of the 4 microelements.Mixed litter decomposition of R.pseudoacacia with Pinus tabulaeformis and Larix principis-rupprechtii separately would promote release of Cu,but inhibit releases of Zn,Ni and Cd.Mixed litter decomposition of R.pseudoacacia with Q.liaotungensis would promote releases of Zn and Cd,but inhibit releases of Cu and Ni.【Conclusion】Mixed forestation of R.pseudoacacia with other trees which promote release of microelements after mixed litter decomposition would be helpful for the microelement cycling and utilization in forestland.