贵州马岭河瀑布钙华藻类群落特征及生物岩溶作用

Characteristics of tufa algae community and bio-karstification at the Malinghe waterfall in Guizhou

为探讨水流干扰和钙华藻类群落在瀑布钙华形成过程中的作用,于2007年8月对贵州马岭河峡谷天星画廊景区内3条瀑布钙华流水区、浸润区和潮湿区进行了采样,分析其种类组成、群落类型和形态、分布特征等。结果显示:(1)天星画廊景区的瀑布钙华藻类群落类型包括胶质颗粒状、胶质团块状、垫状、绒毡状和粉末状5种类型,钙华藻类以蓝藻占优势,在受水流中等程度干扰的生境中(浸润区)钙华藻类物种多样性和群落多样性较高;(2)钙华藻类群落对瀑布钙华的形成同时存在沉积和溶蚀作用,藻类群落可影响瀑布钙华沉积和溶蚀的方向性;(3)在中等程度水流干扰作用下,钙华藻类群落在瀑布钙华形成过程中以沉积作用为主,在强或弱水流干扰作用下,则以溶蚀作用为主。因此认为:水流干扰程度和藻类群落类型共同作用是控制瀑布钙华形态构造多样化的主要因素之一;水流的中度干扰有利于瀑布钙华的形成。

Carbonates of the Triassic system,widely distributing in the Malinghe gorge,mainly form gorge,peak cluster,peak forest,stone forest landscapes.Among the geomorphologic landscape,there is a 2 km long gorge called the Tianxing gallery locating at 104°56＇E and 25°08＇N.The gallery has typical waterfall tufa that presents the appearance as vertical curtain,lobes and scaly.In order to investigate the role of flow interference and algae community during the development of the tufa at waterfall,the algae samples are collected at the fluid,inundation and moist regions from 3 waterfalls at the Tianxing gallery in August,2007.The morphological characteristics of tufa algal communities are recorded at field.The samples are divided into subsamples of algae and matrix which treated with 5 ％ C2H4O2 and 1 ％ HC1 respectively.Then,the treated subsamples are analyzed qualitatively and quantitively after being mixed to each other.The micromorphology samples of tufa are observed under the stereo microscope.The micro-deposit is separated from the sample and then added with a little 1％ HC1 to observe the nucleus of micro-deposit.The results show that there are 5 algae coenotypes in the waterfall involving granular,lumps,mat,felty and pulverous.The dominant assemblage in the tufa algae is cyanophyta.In the moderate disturbed habitats by water flow,the species and community diversity are higher in the inundation region than other regions.Deposition and dissolution also take place in the tufa algae communities during the development of waterfall tufa,which may affect the direction of deposition and dissolution.The main role of tufa algae community is deposition under the condition of moderate disturbance by flow during the development of waterfall tufa,while under the conditions of stronger or weak disturbance of flow,the main role is dissolution.Therefore,it is considered that the synergism of flow disturbance degree and coenotype is one of the main factors that controlling the diversification in shape and structure of the waterfall tufa.And the moderate disturbance of flow is favorable for deposition of waterfall tufa.