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首页> 外文期刊>Plant and Soil >Soil water availability effects on seed germination account for species segregation in semiarid roadslopes.
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Soil water availability effects on seed germination account for species segregation in semiarid roadslopes.

机译：土壤水分对种子萌发的影响是半干旱坡地物种隔离的原因。

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Previous studies report that the low colonization success on eroded roadslopes of semiarid environments is controlled by microsite limitations. We predicted that soil water availability, through its effect on seed germination, is a determinant factor in the colonization process of roadslopes in semiarid environments. Moreover, we predicted that the success of species establishment on the harshest roadslope conditions (i.e., south-facing roadcuts) is either due to the ability of seeds to germinate fast at low water potentials (colonizing species) or to the ability of plants to sprout (resistant species). Specifically we present evidence for: (1) soil drying occurs faster on roadcuts than on roadfills after a rainfall event; (2) germination is a filtering process that influences the success of species establishment on roadslopes; (3) species able to colonize successfully south-facing roadcuts have higher germination rates and a shorter time to germination under water-stress conditions than species able to colonize successfully but exclusively the most favourable roadslopes (i.e., roadfills); (4) species that live on south-facing roadcuts and have the ability to sprout do not necessarily germinate with germinating rates and speeds as high as species that colonize successfully these slopes but are unable to sprout. To test these hypotheses we compared water dynamics in the soil among roadslope types and aspects as well as the seed ability to germinate at low water potentials among species showing different regeneration strategies and establishment success on roadslopes. Soil water availability after rainfalls occurring during the germination period played a major role in the germination of seeds. The patterns of seed germination under water-stress conditions were consistent with the success of colonizing species on roadslopes and with the distribution of adult plants in the roadslopes 8 years after these latter were built. We discuss the usefulness of these results for the improvement of revegetation projects in semiarid areas by means of an appropriate selection of species adapted to the local environmental conditions. We suggest that the ability of species to germinate under water stress could be an indication of a species' potential for success under semiarid conditions..
机译：先前的研究报告说，半干旱环境在侵蚀的路边坡上的低定居成功率受到微地点限制的控制。我们预测，土壤水的可利用性，通过其对种子发芽的影响，是半干旱环境中路坡定植过程的决定性因素。此外，我们预测，在最恶劣的道路坡度条件下（例如，朝南的道路）成功建立物种的原因可能是种子具有在低水位条件下快速发芽的能力（定殖的物种）或植物发芽的能力（抗性物种）。具体而言，我们提供以下证据：（1）降雨过后，路基上的土壤干燥比道路填土上的干燥更快; （2）发芽是一个过滤过程，会影响在斜坡上建立物种的成功; （3）与能够成功定居但仅最有利的路坡（即填埋场）的物种相比，能够成功定居于南向道路的物种在水分胁迫条件下具有更高的发芽率和更短的发芽时间; （4）生活在朝南的道路上并具有发芽能力的物种不一定以与成功在这些斜坡上定植但无法发芽的物种一样高的发芽率和发芽速度发芽。为了检验这些假设，我们比较了不同坡向和不同坡向之间物种在不同坡向和坡向之间的土壤水分动态以及低水势下种子发芽的能力。发芽期间发生降雨后的土壤水分利用率在种子发芽中起主要作用。水分胁迫条件下的种子萌发模式与在坡道上定植物种的成功以及在这些坡道建成后8年在坡道上成年植物的分布是一致的。我们通过适当选择适合当地环境条件的物种，讨论了这些结果对改善半干旱地区的植被恢复项目的有用性。我们建议物种在水分胁迫下发芽的能力可能表明该物种在半干旱条件下成功的潜力。

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