中国北方森林植被主要表土花粉类型对植被的指示性

INDICATION OF SOME MAJOR POLLEN TAXA IN SURFACE SAMPLES TO THEIR PARENT PLANTS OF FOREST IN NORTHERN CHINA

中国北方森林植被68个表土花粉样品中,主要花粉类型联合指数(A)、超代表性指数(O)、低代表性指数(U)、R值、植被不存在时花粉百分比最大值(Xa)和平均值(Ma)、植被存在时花粉百分比最大值(Xp)和平均值(Mp)的计算表明:胡桃、青檀、禾本科、菊科、莎草科、皂荚等A值较高,O值及U值均较低,对植被指示明显,为适中代表性类型;云杉、冷杉、栎、鼠李、沙枣、落叶松、榆、杨、黄栌、花椒、木犀科、绣线菊、毛茛科、榛等,尽管A值和O值大于0.5,但Xa远低于Mp,R值小于1,对植被指示意义较明显,属低代表性类型;桦、松、蒿、藜科等,A值适中,O值和R值较高,U值较低,但Xa,Xp和Ma值较高,属超代表性类型,对植被有一定的指示意义;其他花粉类型对植被指示性不明显或需进一步研究。花粉百分比与植物盖度关系研究表明,多数在森林中建群或为优势成分的乔木花粉与母体植物呈显著线性相关关系,森林植被中的伴生乔木、灌木和多数草本花粉与植物盖度无明显的线性相关关系。松花粉30%以上,可能有松林存在;云、冷杉林中云杉、冷杉花粉高于20%,无云杉植物存在时云、冷杉花粉低于5%;落叶松林中落叶松花粉低于20%,落叶松在植被中不占优势时花粉百分比低于5%,周围植被无落叶松存在时花粉百分比多低于1%;桦木林中桦树花粉高于40%,无桦属植物存在时桦属花粉多低于5%;栎树林中栎属花粉百分比高于10%,无栎属植物存在时栎属花粉多低于1%;鹅耳枥林中鹅耳枥林花粉低于15%,无鹅耳枥植物存在时鹅耳枥花粉多低于1%;杨树纯林中杨树花粉百分比约0～5%,杨属与其他阔叶树混交时杨花粉不易被记录到;胡桃楸纯林中胡桃花粉所占百分比约为25%～35%,无胡桃属植物存在时胡桃花粉低于1%;青檀林中青檀花粉低于15%,无青檀属植物存在时青檀花粉也不出现;榆树林中榆树花粉约8%～20%,榆树与其他阔叶树混交时榆树花粉低于1%。

The associated index （A）, over-represented index （O）, under-represented index （U）, R-values, pollen percentage maximum （Xa） and mean values （Ma） where the parent plants absent, pollen percentage maximum （Xp） and mean values （Mp） where the parent plants present are calculated for some major pollen types based on 68 forest surface samples in northern China. The results show that some pollen taxa such as Juglans, Pterocehis, Gramineae, Compositae, Cyperaceae and Gleditsia can indicate their parent plants very well, owing to high Avalues and low U-values and O-values; Some pollen taxa such as Picea, Abies, Quercus, Rhamnaceae, Elaeagnus, Larix, Ulmus, Populus, Cotinus, Zanthoxylum, Oleaceae, Spiraea, Ranunculaceae and Corylus are underrepresented pollen types, and have important indication to their parent plants, because the R-values are less than 1 and the Xa values are much less than the Mp values in these pollen types, though A-values are less than 0.5 and the O-values are more than 0.5. Betula, Pinus, Artemisia and Chenopodiaceae have high O and R-values, very low U-values, and high Xp, Xa and Ma-values. Thus, they are over-presented pollen types, and have some indication to their paerent plants. The indications of other pollen types are not obvious or need further work to clarify. The relationship between pollen percentage and vegetation covers indicates that pollen percentages and parent plant cover are correlated significantly for most of dominated or abundant arboreal pollen types, and are not obviously correlated with most shrubby and herbaceous or companion arboreal pollen types. Pinus pollen percentages are more than 30% in Pinus forest. Picea and Abies pollen percentages are more than 20% in Picea or Abies forest and less than 5% where Picea or Abies trees absent. Larix pollen percentages are less than 20% in Larix forest, but less than 5% where Larix is not dominant in the forest, and less than 1% where Larix trees absent. Betula pollen percentages are more than 40% in the Betula forest, and less than 5% where Betula trees absent. Quercus pollen percentages are more than 10% in Quercus forest and are less than 1% where Quercus trees absent. Juglans pollen percentages are more than 25% in Juglans forest and less than 1% where Juglans trees absent. Populus pollen percentages only are 0 -5% in the Populus forest and can not be easily recorded where Populus are not dominated in forest. Pteroceltis pollen percentages are less than 15% in the Pteroceltis forest, and Pteroceltis pollen does not appear when Pteroceltis trees absent. Ulmus are more than 10% in Ulmus forest, but are less than 1% where Ulmus are not dominated in the forest.