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Phytolith evidence for the extent and nature of prehistoric Californian grasslands

机译：植石证据表明史前加利福尼亚草原的范围和性质

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Californian grasslands have been radically transformed by cultivation and exotic species invasions that began with European settlement in 1769. Because native species contribute only a small percentage of total vegetation cover at most grassland sites in California today, there has been a long-standing controversy regarding the extent and composition of prehistoric grasslands. We used phytolith analysis of soil samples from 153 spatially diverse grassland sites currently cultivated or dominated by exotic annual grasses to provide the first direct evidence that, except for areas near the coast, grass was generally a minor component of the vegetation. Most of the arid, non-wetland Central Valley and surrounding foothills probably had very low grass cover. Combining our data with historical accounts of vegetation encountered by early explorers in California and relict analysis of native species in existing grassland patches, it appears that while the extent of prehistoric grassland was probably similar to the current extent of exotic annual grassland, most areas were likely dominated by a highly diverse assemblage of herbaceous species, composed largely of annual forbs adapted to exploit local environmental heterogeneity. Phytolith analysis should be routinely performed in California to guide grassland restoration efforts. The technique can also be used to reconstruct prehistoric vegetation of highly altered grassland ecosystems worldwide.
机译：自1769年欧洲人定居开始，加利福尼亚州的草原就因耕种和外来物种入侵而发生了根本性的转变。由于当今加利福尼亚州大多数草原地区的原生物种只占植被总覆盖率的很小一部分，因此关于该物种的争议一直存在史前草原的范围和组成。我们对目前由异国一年生草栽培或控制的153个空间不同的草原站点的土壤样品进行了植物残留分析，以提供第一个直接证据，表明除沿海地区以外，草通常仅占植被的一小部分。大部分干旱，非湿地的中央谷地和周围的山麓地带的草皮可能很低。将我们的数据与加利福尼亚早期探险家遇到的植被的历史记录以及现有草地斑块的原生物种的遗迹分析结合起来，看来，尽管史前草原的范围可能与目前的异国一年生草原的范围相似，但大多数地区可能由高度多样化的草本物种组成，主要由适于利用当地环境异质性的一年生小穗组成。应当在加利福尼亚定期进行植硅石分析，以指导草原恢复工作。该技术还可以用于重建全世界高度变化的草原生态系统的史前植被。

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