PLANT-RESPONSES TO FERTILIZATION AND SPECIES REMOVAL IN TUNDRA RELATED TO COMMUNITY STRUCTURE AND CLONALITY
PLANT-RESPONSES TO FERTILIZATION AND SPECIES REMOVAL IN TUNDRA RELATED TO COMMUNITY STRUCTURE AND CLONALITY
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DOI：
10.2307/3544968
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发表时间：
1992-04-01
期刊：
影响因子：
3.4
通讯作者：
JONASSON, S
中科院分区：
文献类型：
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作者：
JONASSON, S
1984 年，通过以下方法对一系列苔原植物群落进行了干扰实验：1）在三个稳定的和两个冻胀地点施用氮磷钾肥料；2）从三个稳定的苔原地点去除主要的落叶灌木。 1985年、1986年和1988年，通过点截距测量了扰动地块和未扰动对照地块的垂直投影植物面积（PPA）的影响。1984-1988年间，对照地块和去除地块上的维管束植物和苔藓植物的PPA没有显着变化，地衣也几乎没有变化。施肥显着增加了维管植物的PPA，降低了地衣的PPA，增加或减少了苔藓植物的PPA。只有两种维管束物种的 PPA 下降，而 21 个物种的 PPA 上升。在控制或去除地点，物种多样性并未发生一致变化。然而，在稳定苔原受精后，维管植物中的该值显着增加，而在受精的冻胀苔原上则下降。在隐花植物（苔藓植物和地衣）中，受精后物种多样性总是下降。在去除灌木后稳定苔原上剩余维管束物种缺乏变化表明来自它们的竞争并不是共生物种生长的主要限制因素。稳定的苔原受精后，维管束植物的多样性增加而不是减少，并且在生长高峰期对几乎所有物种的丰度没有负面影响，这表明一旦养分限制被释放，竞争排斥性较低：确实发现了一些积极的植物相互作用。受精地的隐花植物和受精冻胀苔原上的维管植物多样性的下降表明，与稳定苔原上的维管植物相比，它们对竞争排斥的敏感性更高。建议这种差异与群落结构和群落维管成分之间克隆性的差异有关。
A range of tundra plant communities were experimentally perturbed in 1984 by 1) application of N P K-fertilizer to three stable and two frost-heaved sites and 2) by removal of the dominant deciduous shrubs from the three stable tundra sites. Effects on vertically projected plant area (PPA) on perturbed plots and on unperturbed controls were measured by point intercepts in 1985, 1986 and 1988.There were no significant changes of the PPA of vascular plants and bryophytes on the control and removal plots during 1984-1988, and few changes among lichens. Fertilization increased the PPA of vascular plants strongly, reduced the PPA of lichens and increased or reduced the PPA of bryophytes. The PPA of only two vascular species declined, whereas that of 21 species increased.Species diversity did not change consistently on control or removal sites. It increased considerably, however, among vascular plants after fertilization of stable tundra and declined on fertilized frost-heaved tundra. Among cryptogams (bryophytes plus lichens), species diversity always declined after fertilization.The lack of changes in remaining vascular species on stable tundra after removal of the shrubs suggests that competition from them was not a major limiting factor to the growth of co-occurring species. The increased rather than decreased diversity of vascular plants after fertilization of stable tundra, and the lack of negative effects on abundance of almost all species during the growth flush, demonstrate low competitive exclusion once nutrient limitation is released: indeed some positive plant interactions were identified. The decline of diversity among cryptogams on fertilized sites and among vascular plants on fertilized frost-heaved tundra indicate a higher sensitivity to competitive exclusion than among the vascular plants of stable tundra. It is suggested that the differences relate to community structure and differences in the clonality among the vascular components of the communities.