煤的显微组分定义与分类(ICCP system 1994)解析Ⅲ:腐植体

国际煤地质学杂志(International Journal of Coal Geology)在2005年发表了褐煤腐植体显微组分的分类方案。由于我国没有低阶煤中腐植体的显微组分分类方案,因此“ICCP System 1994”中关于腐植体的显微组分的定义和分类方案对我国学者更具有特殊的意义。该显微组分分类方案(ICCP system 1994)在原分类方案的基础上,对腐植体显微组分的分类进行了修订,以便能够使其与其他显微组分,特别是镜质体分类中的相关术语更相匹配。该分类方案将腐植体显微组分为3个亚组,分别是结构腐植体亚组、碎屑腐植体亚组、凝胶腐植体亚组;每个显微组分亚组又分为2个显微组分,显微组分可以进一步分为显微亚组分以至显微组分种。虽然本分类方案主要针对的褐煤(指腐植体平均随机反射率低于0.4%的低阶煤,或称之木质褐煤),但适合于褐煤和亚烟煤,主要是因为镜质体和腐植体,以及次级的显微组分亚组之间具有对应的关系,因此,“ICCP system 1994”分类方案的腐植体和镜质体2种分类体系可以并行使用。目前,在显微组分以及细化的分类方面,研究者可根据低阶煤的性质和分析目的,选择腐植体和镜质体2个分类体系中的其中一种使用。这与新的ISO煤的分类方法一致。在ISO分类中,也涵盖了低阶煤,并且提出,对于低阶煤可联合使用腐植体和镜质体2种分类方法。

The role of soil-borne fungi in driving the coexistence of Pinus massoniana and Lithocarpus glaber in a subtropical forest via plant-soil feedback

Aims Plant–soil feedback(PSF)is a key mechanism that can facilitate tree species coexistence and diversity.Substantial evidence suggests that species-specific soil-borne pathogens around adult trees limit the performance of home(conspecific)seedlings relative to foreign(heterospecific)seedlings.However,the underlying mechanism remains largely elusive.Methods Here,we conducted a reciprocal transplant pot experiment using seedlings and from two tree species,Pinus massoniana and Lithocarpus glaber that are dominant and coexist in a subtropical,evergreen,broad-leaf forest in Gutianshan,Zhejiang Province of eastern China.We examined how seedlings from the two tree species responded to soils originating from underneath their own versus the other tree species,using a full-factorial design.Additionally,we added a fungicide(benomyl)to half of the pots to evaluate the role of soil-borne fungi on seedling growth.Important Findings We found that the seedlings from L.glaber grew better in soils that were collected from beneath the canopy of P.massoniana,while seedling growth of P.massioniana was not affected by soil origin.The addition of fungicide benomyl resulted in a shift towards more positive PSF effects for L.glaber,indicating that L.glaber seedlings performed better in their own soils than in soils from P.massoniana in the absence of fungi.Our findings highlight the importance of soil-borne pathogenic and ectomycorrhizal fungi in driving PSF,and indicate that PSF may promote the coexistence of two subtropical tree species by reducing the performance of L.glaber in own soils.