Defining the limit to resistance in a drought-tolerant grassland: long-term severe drought significantly reduces the dominant species and increases ruderals
Defining the limit to resistance in a drought-tolerant grassland: long-term severe drought significantly reduces the dominant species and increases ruderals
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DOI：
10.1111/j.1365-2745.2011.01864.x
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发表时间：
2011-11-01
影响因子：
5.5
通讯作者：
Burke, Ingrid C.
中科院分区：
文献类型：
--
作者：
Evans, Sarah E.;Byrne, Kerry M.;Burke, Ingrid C.
1.模型预测，在未来的气候状况下，干旱的持续时间和强度将增加。虽然半干旱草原适应水分限制，但半干旱草原植被对未来可能出现的极端和持续干旱期的敏感性尚未得到验证.在这项研究中，我们分析了植被覆盖数据，从11年的干旱操纵在半干旱短草草原在科罗拉多，美国。我们研究了在生长季节期间，在接收25%和50%环境降水的样地中，总植被覆盖、优势植物（Bouteloua gracilis）覆盖和杂草覆盖的变化。我们发现，11年的干旱导致总覆盖和覆盖的优势种的大幅减少，但显着的差异并没有出现，直到第4和第7年的干旱。干旱严重程度显着影响的程度，在干旱后期杂草覆盖增加，但减少B。不同干旱强度下，干旱下的薄股肌盖度差异不显著。细叶草的减少与杂草覆盖和物种丰富度的增加有很强的对应关系，表明优势种在维持短草草原群落结构中起着重要作用.合成.我们的研究结果表明，短草草原，尤其是优势种B。在未来几十年里，长期干旱可能会更加普遍，从而严重影响到淡水、淡水和淡水。通过量化耐旱系统的抗性极限，我们的研究结果可以为新气候条件下草地系统的稳定性和管理决策提供理论依据，并为以前和未来的操纵研究提供新的时间背景。
1. Models predict that the duration and intensity of drought will increase under future climate regimes. Although semi-arid grasslands are adapted to moisture limitation, the sensitivity of semi-arid grassland vegetation to extreme and sustained dry periods that may occur in the future has not been tested.2. In this study, we analysed vegetation cover data from an 11-year drought manipulation in the semi-arid shortgrass steppe in Colorado, USA. We examined changes in total vegetation cover, dominant plant (Bouteloua gracilis) cover and ruderal cover in plots receiving 25% and 50% of ambient precipitation during the growing season.3. We found that 11 years of drought resulted in large reductions in total cover and cover of the dominant species, but significant differences did not emerge until the 4th and 7th year of drought. Drought severity significantly influenced the degree to which ruderal cover increased in the later period of the drought, but reductions in B. gracilis cover under drought were not significantly different under different drought severities. Bouteloua gracilis reduction did correspond strongly with increases in ruderal cover and species richness, suggesting that the dominant species plays a strong role in maintaining the structure of communities in the shortgrass steppe.4. Synthesis. Our results suggest that the shortgrass steppe, and most notably the dominant species B. gracilis, can be significantly perturbed by long-term droughts that may be more common in future decades. By quantifying the resistance-limit of a drought-tolerant system, our results can inform theories of stability and management decisions for grassland systems under new climate regimes and provide a new temporal context for previous and future manipulation studies.