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首页> 外文期刊>Journal of Vegetation Science >Spatio-temporal variation in the effect of herbaceous layer on woody seedling survival in a Chilean mediterranean ecosystem
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Spatio-temporal variation in the effect of herbaceous layer on woody seedling survival in a Chilean mediterranean ecosystem

机译：智利地中海生态系统中草本层对木本幼苗存活的影响的时空变化

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Questionsc What is the effect of herbaceous layer on seedling establishment of three woody pioneer species in open areas of central Chile under a semi-arid mediterranean climate? How do inter-annual and habitat conditions (slope aspect) modulate this effect? Under high stress conditions such as the drier year and habitat (north-facing slope) do herbs reach low abundance and have neutral effects on woody seedlings? Under medium stress conditions for these woody species, such as the wetter year and south-facing slope, does the herbaceous layer reach greater abundance and have positive effects on woody seedlings due to increasing soil water content?Location: A watershed on the outskirts of Santiago, Chile, subjected to clearing of woody vegetation through firewood extraction and human-set fires.Methods: In spring 2007, we set up 20 plots (3 m x 2 m). Half of each plot had herbs removed manually and by application of herbicide. In both halves of each plot, one seedling (8 months old) of each of the three native woody species (Colliguaya odorifera, Schinus polygamus and Quillaja saponaria) was planted and survival monitored subsequently. The experiment was repeated in two consecutive growing seasons (2007-2008 and 2008-2009) that differed significantly in total precipitation (152 and 256.5 mm, respectively), and replicated in two sites that differed in aspect and abiotic conditions: a moister south-and a drier north-facing slope.Results: In the first and drier year, the herbaceous layer had low cover and no significant effect on seedling survival of woody species. During the second year, herbs had greater cover and a significant positive effect on spring survival of C. odorifera in the north-facing slope, which was lost after summer. During this wetter year on the south-facing slope, herb cover had a positive effect on survival of S. polygamus (mainly during summer).Conclusions: The role of mostly ruderal herbs on woody seedling establishment depended on the species, rainfall of the current year and slope aspect, and may be explained by soil moisture patterns. This suggests that the effect of ruderal herbs on woody seedlings shifts from neutral under high stress conditions produced by drought to positive under moderate stress conditions. Our results contribute to understand interactions between ruderal herbs and woody species under contrasting abiotic conditions. Therefore, control of the herbaceous layer may not be needed in restoration programmes for this region. Moreover, herbs may benefit restoration of woody cover in mesic habitats.
机译：Questionsc在半干旱的地中海气候下，草本层对智利中部开放地区三种木本先驱物种的幼苗生长有何影响？年际和栖息地条件（坡度）如何调节这种影响？在诸如干旱年份和栖息地（朝北的斜坡）等高胁迫条件下，草本植物的丰度是否低，并且对木本植物幼苗有中性影响？在这些木本物种处于中等胁迫条件下，例如较湿的年份和朝南的坡度，由于土壤含水量增加，草本层是否会达到更高的丰度并对木本幼苗产生积极影响？智利的木本植物通过采伐柴火和人工篝火清除。方法：2007年春季，我们建立了20个地块（3 mx 2 m）。每个地块的一半都通过人工除草剂去除了草药。在每个样地的两半中，分别种植三种天然木本物种（Colliguaya odorifera，Schinus polygamus和Quillaja saponaria）的一株幼苗（8个月大），并随后监测其存活。在连续两个生长季节（2007-2008年和2008-2009年）重复进行该实验，这两个季节的总降水量显着不同（分别为152和256.5 mm），并在纵横比和非生物条件不同的两个地点重复进行：结果：在第一年和较干燥的一年，草本层的覆盖率较低，对木本植物的幼苗存活没有显着影响。在第二年中，药草具有更大的覆盖度，并且对北坡的香椿春季生存产生了显着的积极影响，该物种在夏季后消失了。在这个潮湿的一年中，朝南的斜坡上，草皮覆盖对杂草S. polygamus的存活有积极的影响（主要在夏季）。结论：多数草在木本植物育苗中的作用取决于物种，当前的降雨年和坡度方面，并且可以用土壤湿度模式来解释。这表明，药对木本幼苗的影响从干旱引起的高胁迫条件下的中性转变为中等胁迫条件下的正性。我们的研究结果有助于理解在非生物条件下草与木本物种之间的相互作用。因此，在该区域的恢复程序中可能不需要控制草层。此外，草药可能有益于恢复中性生境中的木质覆盖物。

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