Plant responses to fertilization and exclusion of grazers on an arctic tundra heath
Plant responses to fertilization and exclusion of grazers on an arctic tundra heath
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DOI：
10.1034/j.1600-0706.2002.980202.x
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发表时间：
2002-08-01
期刊：
影响因子：
3.4
通讯作者：
Grellmann, D
中科院分区：
文献类型：
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作者：
Grellmann, D
本研究调查了施肥和放牧挪威旅鼠（Lemmus lemmus），灰边田鼠（Clethrionomys rufocanus），驯鹿（Rangifer tarandus）对不同的苔原植物群落为主的落叶灌木的影响。八个研究区域中的四个，每个区域面积为2500 m2，施用氮磷钾肥料，四个区域作为未施肥的对照。在每个研究区内使用了两种围栏，一种是只排除驯鹿，另一种是既排除啮齿动物又排除驯鹿。开放的放牧地块作为对照。在施肥事件后的5年期间，使用点频率方法监测围栏内外植被的变化。采用现场诱捕法和越冬个体巢数法调查了施肥区和未施肥区的鼠密度。驯鹿在生长季节不在研究地区吃草，但在秋季和春季迁徙通过该地区。施肥增加了丰富的维管植物，而放牧驯鹿和啮齿动物减少了丰富的维管植物显着施肥和未施肥的地区。啮齿动物喜欢在冬季施肥区，减少丰富的欧洲越橘和越橘vitis-idaea，而很少放牧发生在夏季。禾本科植物表现出最强的积极响应施肥和占主导地位的植物群落上未放牧的地块，而冬季放牧驯鹿和啮齿动物显着降低了禾本科植物的丰度。落叶灌木（矮桦，越橘）略有增加，但显着，由于施肥和万年青矮灌木施肥没有反应。然而，使用功能的生长形式来预测养分富集和放牧的反应必须受到质疑，施肥的反应以及草食动物的偏好被证明是物种特异性的，而不是统一的功能组内基于植物生长形式。
This study investigated the impacts of fertilization and grazing by Norwegian lemmings (Lemmus lemmus), grey-sided voles (Clethrionomys rufocanus), and reindeer (Rangifer tarandus) on a diverse tundra plant community dominated by deciduous shrubs. Four out of eight study areas, having a size of 2500 m(2) each, were fertilized with a N-P-K fertilizer and four areas served as unfertilized controls. Two types of exclosures were used within each study area, one to exclude solely reindeer, and one to exclude both rodents and reindeer.,Open, grazed plots served as controls. During 5 years following the fertilization event the changes in vegetation inside and outside the exclosures were monitored using a point frequency method. The densities of rodents on the fertilized and unfertilized areas were investigated by live trapping and by counting nests of overwintering individuals. Reindeer do not graze on the study area during the growing season but migrate through this area in autumn and spring. Fertilization increased the abundance of vascular plants while grazing by reindeer and rodents decreased the abundance of vascular plants significantly on both fertilized and unfertilized areas. Rodents preferred clearly the fertilized areas during winter, decreasing the abundance of Vaccinium myrtillus and Vaccinium vitis-idaea, while very little grazing occurred during summer. Graminoids showed the strongest positive response to fertilization and dominated the plant community on ungrazed plots, while winter grazing by both reindeer and rodents significantly decreased the abundance of graminoids. Deciduous shrubs (Betula nana, Vaccinitan myrtillus) increased slightly but significantly due to fertilization and evergreen dwarf shrubs showed no response to fertilization. However, the use of functional growth forms for predicting the responses of nutrient enrichment and grazing must be questioned, as responses to fertilization as well as preferences by herbivores were shown to be species-specific rather than uniform within functional groups based on plant growth forms.