Mid-Holocene bottleneck for central European dry grasslands: Did steppe survive the forest optimum in northern Bohemia, Czech Republic?
Mid-Holocene bottleneck for central European dry grasslands: Did steppe survive the forest optimum in northern Bohemia, Czech Republic?
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中欧干旱草原的全新世中期瓶颈：捷克共和国波西米亚北部的草原是否在森林最适宜条件下幸存下来？
DOI：
10.1177/0959683614566218
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
V. Ložek
中科院分区：
文献类型：
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作者：
P. Pokorný;M. Chytrý;L. Juřičková;J. Sádlo;J. Novák;V. Ložek
重温经典的Gradmann的“草原理论”中欧，我们研究早期全新世草原栖息地是否幸存的关键时期最大的全新世造林：中全新世瓶颈。尽管在这一时期，植树造林是一个主要的生态因素，这是无可争议的事实，我们的花粉和软体动物的平行分析发现在干燥的低地地区的北方波希米亚，捷克共和国（Zahájí和Sucheli的波托克网站，下奥赫里德地区）的沉积序列提供了强有力的证据，不间断的地方发生的草原在整个全新世。在新石器时代农业开始时，这一地区被森林草原覆盖。类似于现在的东欧和西伯利亚西南部的森林草原景观，北方波希米亚的干旱地区主要是开放式树冠的松桦林，使许多需要光照的植物物种从冰川晚期和全新世早期到新石器时代持续生存。后来，人为的砍伐森林和牲畜放牧创造了一个半自然的草原。我们的数据表明，这次生草原可以被看作是一个直接延续的晚更新世和全新世早期的自然草原，而不是一个纯粹的文化草原开发后，才不断砍伐森林的全新世中期景观由人类。与此同时，我们提供的证据支持Gradmann的“草原理论”，假设在中欧，新石器时代的农业开始在这些地区，没有完全的森林，但包含残留的天然草原。这一发现对解释中欧目前的生物多样性模式具有重要意义。
Revisiting the classical Gradmann’s ‘steppe theory’ for central Europe, we examine whether the early Holocene steppe habitats survived the critical period of maximum Holocene afforestation: the mid-Holocene bottleneck. Despite the undisputable fact that afforestation was a dominant ecological factor in this period, our parallel analyses of pollen and molluscs from sedimentary sequences discovered in the dry lowland area of northern Bohemia, Czech Republic (Zahájí and Suchý potok sites, lower Ohře area) provide strong evidence for uninterrupted local occurrence of steppe grasslands throughout the Holocene. At the onset of the Neolithic agriculture, this area was covered by forest-steppe. Analogously to the present forest-steppe landscapes of eastern Europe and south-western Siberia, dry areas of northern Bohemia were dominated by open-canopy pine–birch forests that enabled continuous survival of many light-demanding plant species from the late Glacial and early Holocene to the Neolithic. Later on, anthropogenic deforestation and livestock grazing created a semi-natural steppe. Our data suggest that this secondary steppe can be viewed as a direct continuation of the late Pleistocene and early Holocene natural steppe rather than a purely cultural steppe developed only after deforestation of a continuously forested mid-Holocene landscape by humans. At the same time, we provide evidence supporting Gradmann’s ‘steppe theory’, assuming that in central Europe, Neolithic farming started in those areas that were not completely forested but contained remnants of natural steppes. This finding has important implications for the interpretation of present biodiversity patterns in central Europe.