Okano Kyoko, Bret-Harte M Syndonia
Institute of Arctic Biology, University of Alaska, Fairbanks, Fairbanks, AK, USA.
Springerplus. 2015 Feb 13;4:79. doi: 10.1186/s40064-015-0833-x. eCollection 2015.
Climate change is expected to be pronounced towards higher latitudes and altitudes. Warming triggers treeline and vegetation shifts, which may aggravate interspecific competition and affect biodiversity. This research tested the effects of a warming climate, habitat type, and neighboring plant competition on the establishment and growth of white spruce (Picea glauca (Moench) Voss) seedlings in a subarctic mountain region. P. glauca seedlings were planted in June 2010 under 4 different treatments (high/control temperatures, with/without competition) in 3 habitats (alpine ridge above treeline/tundra near treeline /forest below treeline habitats). After two growing seasons in 2011, growth, photosynthesis and foliar C and N data were obtained from a total of 156, one-and-a-half year old seedlings that had survived. Elevated temperatures increased growth and photosynthetic rates above and near treeline, but decreased them below treeline. Competition was increased by elevated temperatures in all habitat types. Our results suggest that increasing temperatures will have positive effects on the growth of P. glauca seedlings at the locations where P. glauca is expected to expand its habitat, but increasing temperatures may have negative effects on seedlings growing in mature forests. Due to interspecific competition, possibly belowground competition, the upslope expansion of treelines may not be as fast in the future as it was the last fifty years.
预计气候变化在高纬度和高海拔地区会更加显著。气候变暖引发树线和植被变化，这可能会加剧种间竞争并影响生物多样性。本研究测试了气候变暖、栖息地类型以及邻近植物竞争对亚北极山区白云杉（Picea glauca (Moench) Voss）幼苗的定植和生长的影响。2010年6月，在3种栖息地（树线以上的高山脊/树线附近的苔原/树线以下的森林栖息地）的4种不同处理（高温/对照温度，有/无竞争）下种植了白云杉幼苗。在2011年经过两个生长季节后，从总共156株存活的一岁半幼苗中获取了生长、光合作用以及叶片碳和氮的数据。温度升高提高了树线以上和附近的白云杉幼苗的生长和光合速率，但降低了树线以下的生长和光合速率。在所有栖息地类型中，温度升高都会增加竞争。我们的研究结果表明，温度升高将对白云杉预计会扩大其栖息地的地区的幼苗生长产生积极影响，但温度升高可能会对在成熟森林中生长的幼苗产生负面影响。由于种间竞争，可能是地下竞争，未来树线的上坡扩展可能不会像过去五十年那样快。
