Pettorelli Nathalie, Mysterud Atle, Yoccoz Nigel G, Langvatn Rolf, Stenseth Nils Chr
Department of Biology, University of Oslo, Centre for Ecological and Evolutionary Synthesis, (CEES) PO Box 1066, Blindern, N-0316 Oslo, Norway.
Proc Biol Sci. 2005 Nov 22;272(1579):2357-64. doi: 10.1098/rspb.2005.3218.
Understanding how climate influences ecosystems represents a challenge in ecology and natural resource management. Although we know that climate affects plant phenology and herbivore performances at any single site, no study has directly coupled the topography-climate interaction (i.e. the climatological downscaling process) with large-scale vegetation dynamics and animal performances. Here we show how climatic variability (measured by the North Atlantic oscillation 'NAO') interacts with local topography in determining the vegetative greenness (as measured by the normalized difference vegetation index 'NDVI') and the body masses and seasonal movements of red deer (Cervus elaphus) in Norway. Warm springs induced an earlier onset of vegetation, resulting in earlier migration and higher body masses. Increasing values of the winter-NAO corresponded to less snow at low altitude (warmer, more precipitation results in more rain), but more snow at high altitude (colder, more precipitation corresponds to more snow) relative to winters with low winter-NAO. An increasing NAO thus results in a spatially more variable phenology, offering migrating deer an extended period with access to high-quality forage leading to increased body mass. Our results emphasize the importance of incorporating spring as well as the interaction between winter climate and topography when aiming at understanding how plant and animal respond to climate change.
了解气候如何影响生态系统是生态学和自然资源管理领域面临的一项挑战。尽管我们知道气候会在任何单个地点影响植物物候和食草动物的表现，但尚无研究直接将地形与气候的相互作用（即气候降尺度过程）与大规模植被动态和动物表现联系起来。在此，我们展示了气候变率（以北大西洋涛动“NAO”衡量）如何与当地地形相互作用，从而决定挪威植被的绿度（以归一化植被指数“NDVI”衡量）以及马鹿（Cervus elaphus）的体重和季节性迁徙。温暖的春季会使植被更早开始生长，导致更早的迁徙和更高的体重。相对于冬季NAO值较低的冬季，冬季NAO值增加对应着低海拔地区积雪减少（温暖、降水增多导致降雨增多），但高海拔地区积雪增多（寒冷、降水增多对应着降雪增多）。NAO增强因此导致物候在空间上的变化更大，为迁徙的鹿提供了更长时间获取优质草料的机会，从而增加体重。我们的研究结果强调了在旨在理解动植物如何应对气候变化时，纳入春季以及冬季气候与地形之间相互作用的重要性。
