Jägerbrand Annika K, Alatalo Juha M, Chrimes Dillon, Molau Ulf
Department of Plant and Environmental Sciences, Göteborg University, P.O. Box 461, 40530 Göteborg, Sweden.
Oecologia. 2009 Sep;161(3):601-10. doi: 10.1007/s00442-009-1392-z. Epub 2009 Jun 25.
Climate change was simulated by increasing temperature and nutrient availability in an alpine landscape. We conducted a field experiment of BACI-design (before/after control/impact) running for five seasons in two alpine communities (heath and meadow) with the factors temperature (increase of ca. 1.5-3.0 degrees C) and nutrients (5 g N, 5 g P per m(2)) in a fully factorial design in northern Swedish Lapland. The response variables were abundances of plant species and functional types. Plant community responses to the experimental perturbations were investigated, and the responses of plant functional types were examined in comparison to responses at the species level. Nutrient addition, exclusively and in combination with enhanced temperature increase, exerted the most pronounced responses at the species-specific and community levels. The main responses to nutrient addition were increases in graminoids and forbs, whereas deciduous shrubs, evergreen shrubs, bryophytes, and lichens decreased. The two plant communities of heath or meadow showed different vegetation responses to the environmental treatments despite the fact that both communities were located on the same subarctic-alpine site. Furthermore, we showed that the abundance of forbs increased in response to the combined treatment of temperature and nutrient addition in the meadow plant community. Within a single-plant functional type, most species responded similarly to the enhanced treatments although there were exceptions, particularly in the moss and lichen functional types. Plant community structure showed BACI responses in that vegetation dominance relationships in the existing plant functional types changed to varying degrees in all plots, including control plots. Betula nana and lichens increased in the temperature-increased enhancements and in control plots in the heath plant community during the treatment period. The increases in control plots were probably a response to the observed warming during the treatment period in the region.
通过在高山景观中升高温度和增加养分有效性来模拟气候变化。我们在瑞典北部拉普兰进行了一项双因素对照后测设计（BACI）的田间试验，在两个高山群落（石南灌丛和草甸）中进行了五个季节的试验，试验因素包括温度（约升高1.5 - 3.0摄氏度）和养分（每平方米5克氮、5克磷），采用完全析因设计。响应变量为植物物种和功能类型的丰度。研究了植物群落对实验扰动的响应，并将植物功能类型的响应与物种水平的响应进行了比较。单独添加养分以及与温度升高相结合添加养分，在物种特异性和群落水平上产生了最显著的响应。添加养分的主要响应是禾本科植物和多年生草本植物增加，而落叶灌木、常绿灌木、苔藓和地衣减少。尽管两个群落都位于同一亚北极高山地区，但石南灌丛和草甸这两个植物群落对环境处理表现出不同的植被响应。此外，我们发现草甸植物群落中，多年生草本植物丰度因温度和养分添加的联合处理而增加。在单一植物功能类型内，大多数物种对强化处理的反应相似，尽管存在例外情况，特别是在苔藓和地衣功能类型中。植物群落结构呈现出BACI响应，即所有样地（包括对照样地）中现有植物功能类型的植被优势关系都发生了不同程度的变化。在处理期间，石南灌丛植物群落中，温度升高处理和对照样地中的矮桦和地衣增加。对照样地中的增加可能是对该地区处理期间观测到的变暖的响应。
