The effect of mean and variance in resource supply on survival of annuals from Mediterranean and desert environments
The effect of mean and variance in resource supply on survival of annuals from Mediterranean and desert environments
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DOI：
10.1007/s00442-003-1435-9
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发表时间：
2004-10
期刊：
影响因子：
2.7
通讯作者：
A. Sher;D. Goldberg;A. Novoplansky
中科院分区：
文献类型：
--
作者：
A. Sher;D. Goldberg;A. Novoplansky
资源可用性通常用年平均数量来表征，而忽略了栖息地内的空间变化和一年内的时间变化。然而，时间和空间变化对于识别低生产力环境（例如沙漠）中的压力源可能尤其重要，在沙漠中，资源经常受到脉冲影响，并且资源更新事件被长期的低资源可用性所分隔开。因此，压力程度将部分取决于充电事件之间的时间长度。在这里，我们研究了施水时间和总量对两个同属对的影响，每个对都有来自低生产力（沙漠）和高生产力（地中海）栖息地的种群。正如预期的那样，在低或中等补给间隔时发现了最高的存活率和最大的生长，并且地中海物种对季节性总量增加的反应幅度大于沙漠物种。在总水量较高的情况下，存活率较高的物种根据间隔长度在等级中进行切换。这些结果表明，资源可用性的时间变化与植物性能的年度总量一样重要，并且对时间动态的响应可能因物种而异。这对社区级流程具有影响，因为竞争层次结构可能会根据资源动态而不仅仅是总可用性进行切换。
Resource availability is often characterized by mean annual amounts, while ignoring the spatial variation within habitats and the temporal variation within a year. Yet, temporal and spatial variation may be especially important for identifying the source of stress in low productivity environments such as deserts where resources are often pulsed and resource renewal events are separated by long periods of low resource availability. Therefore, the degree of stress will be determined in part by the length of time between recharge events. Here, we investigated the effect of timing and total amount of water application on two congeneric pairs, each with a population from a low (desert) and a high (Mediterranean) productivity habitat. As expected, highest survival and greatest growth were found at low or intermediate recharge intervals, and the magnitude of response to increases in total seasonal amounts was greater for Mediterranean species than desert species. The species that had greater survival switched in the hierarchy under high total water depending on interval length. These results demonstrate that temporal variation in resource availability can be as important as annual total amounts for plant performance and that response to temporal dynamics can vary between species. This has implications for community-level processes, as competitive hierarchies may switch based on resource dynamics rather than only total availability.