Tolerance of an expanding subarctic shrub, Betula glandulosa, to simulated caribou browsing.
Tolerance of an expanding subarctic shrub, Betula glandulosa, to simulated caribou browsing.
复制标题
DOI：
10.1371/journal.pone.0051940
复制
发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Côté SD
中科院分区：
文献类型：
--
作者：
Champagne E;Tremblay JP;Côté SD
据报道，在许多亚北极地区，灌木层的密度增加，这对大型食草动物及其资源的影响提出了疑问。灌木可以容忍浏览和他们的容忍程度可能会受到浏览和土壤生产力，最终修改资源的驯鹿。我们的目的是评估亚北极灌木，腺桦的补偿生长潜力，与驯鹿的啃食和植物的养分供应有关。我们使用模拟浏览（0，25和75%的可用枝条）和氮肥（0和10 g m−2）实验来测试两个主要的假设，将耐受性与资源可用性联系起来，补偿连续假说和生长速率假说以及限制资源模型的预测。我们试图明确整合相对浏览压力在我们的预测，因为组织的数量删除可能会影响长寿植物的补偿能力。桦树充分补偿中度浏览与整体叶生物量类似的未浏览桦树，但在沉重的浏览压力下补偿不足。解释补偿的主要机制似乎是短枝转化为长枝。叶面积增加沉重的浏览压力下，但只导致补偿不足。施肥连续两年没有影响白桦的反应，因此，我们的结论是，我们的研究结果支持LRM假设的高，低氮供应量下的耐受性相同。我们的研究结果强调，在矮桦补偿性增长的潜力是超越独立的施肥制度下沉重的浏览压力。在全世界驯鹿群减少的背景下，浏览压力的减少可以与全球气候变化协同作用，促进目前在亚北极地区报告的灌木扩张。
Densification of the shrub layer has been reported in many subarctic regions, raising questions about the implication for large herbivores and their resources. Shrubs can tolerate browsing and their level of tolerance could be affected by browsing and soils productivity, eventually modifying resource availability for the caribou. Our objective was to assess the compensatory growth potential of a subarctic shrub, Betula glandulosa Michx., in relation with caribou browsing and nutriment availability for the plants. We used a simulated browsing (0, 25 and 75% of available shoots) and nitrogen-fertilisation (0 and 10 g m−2) experiment to test two main hypotheses linking tolerance to resource availability, the Compensatory Continuum Hypothesis and the Growth Rate Hypothesis as well as the predictions from the Limiting Resource Model. We seek to explicitly integrate the relative browsing pressure in our predictions since the amount of tissues removed could affect the capacity of long-lived plants to compensate. Birches fully compensated for moderate browsing with an overall leaf biomass similar to unbrowsed birches but undercompensated under heavy browsing pressure. The main mechanism explaining compensation appears to be the conversion of short shoots into long shoots. The leaf area increased under heavy browsing pressure but only led to undercompensation. Fertilisation for two consecutive years did not influence the response of birch, thus we conclude that our results support the LRM hypothesis of equal tolerance under both high and low nitrogen availability. Our results highlight that the potential for compensatory growth in dwarf birch is surpassed under heavy browsing pressure independently of the fertilisation regime. In the context of the worldwide decline in caribou herds, the reduction in browsing pressure could act synergistically with global climate change to promote the current shrub expansion reported in subarctic regions.
登录
查看更多内容
影响因子：
3.4
作者：
Gough, Laura;Ramsey, Elizabeth A.;Johnson, David R.
通讯作者：
Johnson, David R.
DOI：
10.1078/1617-1381-00020
发表时间：
2003-01-01
期刊：
Journal for Nature Conservation (Jena)
影响因子：
--
作者：
Bergstrom, Roger;Edenius, Lars
通讯作者：
Edenius, Lars
影响因子：
3.4
作者：
DANELL, K;BERGSTROM, R
通讯作者：
BERGSTROM, R
影响因子：
3.4
作者：
Guillet, C;Bergström, R
通讯作者：
Bergström, R
影响因子：
5.2
作者：
Aerts, Rien;Callaghan, Terry V.;Cornelissen, Johannes H. C.
通讯作者：
Cornelissen, Johannes H. C.