PROSPECTS AND LIMITS OF A PHYTOLITH KEY FOR GRASSES IN THE CENTRAL UNITED-STATES
PROSPECTS AND LIMITS OF A PHYTOLITH KEY FOR GRASSES IN THE CENTRAL UNITED-STATES
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DOI：
10.1016/0305-4403(84)90016-5
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发表时间：
1984-01-01
影响因子：
2.8
通讯作者：
BROWN, DA
中科院分区：
文献类型：
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作者：
BROWN, DA
以北美中部常见的112种草为基础的蛋白石植硅体鉴定检索表，为草原古植物地理学的解释提供了许多可能性。关键发展的方法，以及以表格支持的提纲形式的关键总结。该检索表将所有植硅体划分为8个主要形状类别，而这些类别又按次要形状特征进行细分。植株各主要部位的形状差异较大。所考察的大多数物种的种内差异主要是大小的差异，似乎与植物的活力有关。这一规则的一个显著例外是细根植硅体，它的根部植硅体的形状表现出极大的变异性。主要植硅体纲的族内和亚科内变异不大。然而，不同的部落和亚科在三个形状类别的重要性上有很大的不同：双叶、鞍形和梯形。某些梯形形状与鞍形或双叶型的比率可以提供具有C4和C3途径的草的相对优势信息。在层状沉积物中发现的这些比率的波动可能反映了仲夏气温随时间的变化，但有几个误差来源必须分开检查。属于Twiss等人的类的植硅体。(1969)(现在的Pooicoideae)已经在Aristideae，Eragrosteae和andpogoneae部落中被发现。芦荟属植物中也普遍存在白藜芦亚科和绿藻亚科的马鞍形，丹参亚科植物中也存在双叶类(哑铃)。北美中部草原中最重要的分类群之间有足够的差异，如果有分层和可测年的沉积物，就可以确定全新世分类群到达的时间。植硅体分析可以更好地了解主要物种的迁徙速率和来源。
A key for identification of opal phytoliths, based on 112 grass species common to central North America, presents a number of possibilities for interpretation of paleophytogeography of the grasslands. The methods of key development, together with a summary of the key, in the form of an outline supported by tables. The key divides all phytoliths into 8 major shape categories, which in turn are subdivided by minor shape characteristics. The variability of shapes among the major plant parts is large. Within-species variations for most of the species examined are primarily size variations that seem to be related to plant vigor. A striking exception to this rule is Bouteloua gracilis where root phytoliths exhibit extreme variability of shape. Within-tribe and within-subfamily variations in major phytolith classes are not great. Different tribes and subfamilies, however, differ considerably in the importance of 3 of the shape classes: bilobates, saddles and trapezoids. Ratios of certain trapezoid shapes to saddles or bilobates can provide information on the relative dominance of grasses possessing C4 and C3 pathways. Fluctuations in these ratios found in stratified deposits may reflect shifts in midsummer temperature through time, but there are several sources of error that must be examined separately. Phytoliths that fit in the festucoid class of Twiss et al. (1969) (now Pooicoideae) have been seen in the tribes Aristideae, Eragrosteae and Andropogoneae. Saddle shapes of Eragrosteae and Chlorideae are also common in Phragmites australis and bilobates (dumbbells) of the Panicoideae subfamily occur in species of Danthonia. There are sufficient differences among the most important taxonomic groups in the central North American grasslands to allow identification of the time of taxa arrival during the Holocene, if stratified and datable deposits are available. It is possible for phytolith analysis to provide a better understanding of migration rates and sources of major species.