Tall Shrubs Mediate Abiotic Conditions and Plant Communities at the Taiga–Tundra Ecotone
Tall Shrubs Mediate Abiotic Conditions and Plant Communities at the Taiga–Tundra Ecotone
复制标题
高大灌木调节针叶林-苔原生态交错带的非生物条件和植物群落
DOI：
10.1007/s10021-019-00435-0
复制
发表时间：
2019
期刊：
影响因子：
3.7
通讯作者：
J. Baltzer
中科院分区：
文献类型：
--
作者：
Cory A. Wallace;J. Baltzer
在过去的世纪里，灌木丛的扩张已经遍布了北极苔原的大部分地区。预计木本植被的日益占主导地位将对气候模式产生全球影响，并导致水文功能和养分循环的局部变化。改变与灌木相关的非生物条件可能会改变相邻植物的相对适合度，从而导致不同的群落组成。在这里，我们使用了一个广泛的一组配对的非生物和生物的数据，调查的能力Alnus alnobetula（绿色桤木）补丁修改当地植物群落的栖息地在针叶林苔原交错带的西北地区，加拿大。在10个桤木斑块和相邻的无桤木苔原的地形位置上建立了地块。栖息地对应的最强梯度的非生物措施和植物群落组成，表明桤木补丁的生长条件是不同于那些桤木免费苔原的植被变化。在确定环境条件时，坡位一般不重要。桤木斑块通过增加白桦最大高度改变了林下植被的垂直结构。高大的灌木也减少了冻土带专家的丰富度，这表明这些物种面临着来自其范围南部边缘灌木扩张的竞争压力。我们的研究结果表明，高大的灌木斑块可以大大改变他们的当地环境在针叶林-苔原交错带系统，改变现有的栖息地，并作为当地植物群落的生态位建设者。因此，这些栖息地将是重要的水文，营养循环和生物多样性的区域预测考虑灌木继续扩大整个北极。
Shrub expansion has occurred across much of the arctic tundra over the past century. Increasing dominance of woody vegetation is expected to have global influences on climate patterns and lead to local changes in hydrological function and nutrient cycling. Changing abiotic conditions associated with shrubs will likely alter the relative fitness of neighbouring plants resulting in distinct community composition. Here, we use an extensive set of paired abiotic and biotic data to investigate the capacity for Alnus alnobetula (green alder) patches to modify the habitat of the local plant community at the taiga–tundra ecotone of the Northwest Territories, Canada. Plots were established across topographic positions in ten alder patches and adjacent, alder-free tundra. Habitat corresponded to the strongest gradient of among-site variation in abiotic measures and plant community composition, indicating that alder patch growing conditions were distinct from those of alder-free tundra. Slope position was generally unimportant in determining environmental conditions. Alder patches changed the vertical structure of the understory by increasing the maximum height of birch. Tall shrubs also decreased the richness of tundra specialists, suggesting that these species face competitive pressures from shrub expansion at the southern edge of their ranges. Our findings demonstrate that tall shrub patches can substantially modify their local environment in taiga–tundra ecotone systems, altering available habitat and acting as niche constructors for the local plant community. These habitats will therefore be important to consider in regional predictions of hydrology, nutrient cycling, and biodiversity as shrubs continue to expand across the arctic.