RESPONSES OF ARCTIC TUNDRA TO EXPERIMENTAL AND OBSERVED CHANGES IN CLIMATE
RESPONSES OF ARCTIC TUNDRA TO EXPERIMENTAL AND OBSERVED CHANGES IN CLIMATE
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DOI：
10.2307/1939337
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发表时间：
1995-04-01
期刊：
影响因子：
4.8
通讯作者：
LAUNDRE, JA
中科院分区：
文献类型：
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作者：
CHAPIN, FS;SHAVER, GR;LAUNDRE, JA
我们操纵光，温度和营养物质在潮湿的草丛苔原附近的图里克湖，阿拉斯加，以确定如何在这些参数的全球变化可能会影响社区和生态系统过程。其中一些操作改变了养分的可用性，生长形式的组成，净初级生产力和物种丰富度在不到十年的时间，表明在这个网站的北极植被是敏感的气候变化。在一般情况下，短期（3年）的反应是长期（9年）的社区组成的变化预测较差。长期的响应表现出更密切的对应关系，植被分布格局沿着环境梯度。氮和磷的可用性往往增加响应温度升高，反映矿化增加，并在响应光衰减，反映植被养分吸收减少。养分的添加增加了生物量和生产的落叶灌木，但减少了万年青灌木和非维管植物的生长。光衰减降低了所有生长形式的生物量。温度升高提高灌木生产，但减少非维管植物的生产。不同生长形式对温度升高和养分添加的这些对比反应在生态系统水平上“抵消”，缓冲了生态系统特征（如生物量、生产和养分吸收）的变化。温度升高的主要影响是加快植物对土壤资源变化的反应，从长远来看（9年），通过氮矿化的变化来增加养分的有效性。在一个生长形式的物种是彼此相似的资源（光或养分）的变化，但没有一致的反应，温度升高。物种丰富度减少30-50%的温度和营养物质的处理，由于损失的不太丰富的物种。多样性的下降发生在不成比例的杂类草，这是重要的动物营养，并在苔藓，保持土壤热制度。有没有增加丰富的最初罕见的物种在任何treatment.During我们的9年的研究（在该地区有记录以来最热的十年），生物量的一个占主导地位的苔原物种出乎意料地改变了控制地块的方向，我们的实验和全新世花粉记录预测。这表明，区域气候变暖可能已经改变了阿拉斯加北极苔原的物种组成。
We manipulated light, temperature, and nutrients in moist tussock tundra near Toolik Lake, Alaska to determine how global changes in these parameters might affect community and ecosystem processes. Some of these manipulations altered nutrient availability, growth-form composition, net primary production, and species richness in less than a decade, indicating that arctic vegetation at this site is sensitive to climatic change. In general, short-term (3-yr) responses were poor predictors of longer term (9-yr) changes in community composition. The longer term responses showed closer correspondence to patterns of vegetation distribution along environmental gradients. Nitrogen and phosphorus availability tended to increase in response to elevated temperature, reflecting increased mineralization, and in response to light attenuation, reflecting reduced nutrient uptake by vegetation. Nutrient addition increased biomass and production of deciduous shrubs but reduced growth of evergreen shrubs and nonvascular plants. Light attenuation reduced biomass of all growth forms. Elevated temperature enhanced shrub production but reduced production of nonvascular plants. These contrasting responses to temperature increase and to nutrient addition by different growth forms ''canceled out'' at the ecosystem level, buffering changes in ecosystem characteristics such as biomass, production, and nutrient uptake. The major effect of elevated temperature was to speed plant response to changes in soil resources and, in the long term (9 yr), to increase nutrient availability through changes in N mineralization. Species within a growth form were similar to one another in their responses to changes in resources (light or nutrients) but showed no consistent response to elevated temperature. Species richness was reduced 30-50% by temperature and nutrient treatments, due to loss of less abundant species. Declines in diversity occurred disproportionately in forbs, which are important for animal nutrition, and in mosses, which maintain soil thermal regime. There was no increased abundance of initially rare species in response to any treatment.During our 9-yr study (the warmest decade on record in the region), biomass of one dominant tundra species unexpectedly changed in control plots in the direction predicted by our experiments and by Holocene pollen records. This suggests that regional climatic warming may already be altering the species composition of Alaskan arctic tundra.