Increasing intraspecific facilitation in exposed environments: consistent results from mountain birch populations in two subarctic stress gradients
Increasing intraspecific facilitation in exposed environments: consistent results from mountain birch populations in two subarctic stress gradients
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DOI：
10.1111/j.2008.0030-1299.16772.x
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发表时间：
2008-10-01
期刊：
影响因子：
3.4
通讯作者：
Kozlov, Mikhail V.
中科院分区：
文献类型：
--
作者：
Eranen, Janne K.;Kozlov, Mikhail V.
压力梯度假说预测，促进相对于竞争的重要性应该随着压力的增加而增加。这一假设得到了几个环境的支持，但对这一假设的普遍性进行的多梯度研究非常罕见。以山地白桦Betula pubescens subsp. czerepanovii进行测试的两个亚北极应力梯度（海拔和海滨）在科拉半岛，俄罗斯西北部的极端的假设。高应力地点的特点是强风，极端温度和潜在的干旱。从表现性状上验证了非生物胁迫对研究苗木的负面影响。研究了成虫寄主和幼苗-幼苗相互作用的影响。积极的主机幼苗相互作用占主导地位，在每个研究地点，和四个性能变量中的三个表示更强的正净效应在高应力网站。在海滨梯度也幼苗存活给出了类似的解释。此外，一个时间转移到主机幼苗竞争检测到在一个低应力的网站后，两个研究年。在幼苗-幼苗相互作用中，竞争占主导地位，但影响很弱，可能是由于遗传和环境因素引起的“噪音”。我们的研究结果支持应力梯度假设及其在亚北极环境中的普遍性，因为应力梯度和几个健身相关变量的解释是相似的。寄主-幼苗相互作用的时间变化以及寄主-幼苗和幼苗-幼苗效应之间的差异暗示了植物相互作用的大小依赖性：当捐助者比受益者大得多时，促进作用可能占主导地位，而当植物具有相似的大小和发育状态时，竞争可能更强。
The stress-gradient hypothesis predicts that the importance of facilitation relative to competition should increase with increasing stress. The hypothesis has received support from several environments, but multi-gradient studies on the generality of the hypothesis are exceptionally rare. A within-species experiment with mountain birch Betula pubescens subsp. czerepanovii was conducted to test the hypothesis in the extreme ends of two subarctic stress gradients (elevation and seashore) in the Kola Peninsula, northwestern Russia. The high stress sites were characterized by strong winds, temperature extremes and potentially drought. The negative effects of abiotic stress on the study seedlings were verified from performance characteristics. Effects of adult hosts as well as seedling-seedlings interactions were studied. Positive host-seedling interactions dominated in each study site, and three out of four performance variables indicated stronger positive net effects in the high stress sites. In the seashore gradient also seedling survival gave similar interpretations. Also a temporal shift towards host-seedling competition was detected in a low stress site after two study years. In seedling-seedling interactions competition dominated, but the effects were weak, likely due to the 'noise' caused by genetic and environmental factors. Our results support the stress-gradient hypothesis and its generality in subarctic environments, as the interpretations were similar for both stress gradients and several fitness-related variables. The temporal variation in host-seedling interactions and the difference between host-seedling and seedling-seedling effects hint on size-dependency of plant interactions: facilitation might dominate when the benefactor is substantially larger than the beneficiary, while competition may be stronger when the plants are of similar size and developmental status.