Drivers of forest change in the Greater Yellowstone Ecosystem
Drivers of forest change in the Greater Yellowstone Ecosystem
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大黄石生态系统森林变化的驱动因素
DOI：
10.1111/jvs.13141
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发表时间：
2022
影响因子：
2.8
通讯作者：
Li, Hang
中科院分区：
文献类型：
--
作者：
Blomdahl, Erika M.;Speer, James H.;Kaye, Margot;Zampieri, Nicole E.;Rochner, Maegen;Currey, Bryce;Alving, Denise;Cahalan, Gabriel D.;Hagedorn, Ben;Li, Hang
问题预计全球气候变化将导致森林分布和构成的广泛变化，特别是在气候对树木群落排列有强烈控制的山区环境中。人们观察到植被的上坡运动与气温升高有关，这在生态交错带（植被类型之间的过渡带）中尤其明显。我们探讨了干旱和树木死亡率对高海拔森林近期变化的作用。地点美国大黄石生态系统。方法我们沿着跨越主要高海拔植被类型的海拔梯度建立了 19 个森林人口统计样地。结果树木建立日期表明白尾松树线的上坡运动和交错带从 20 世纪 50 年代开始从草地到森林的转变。生长季节的延长可能导致林线向上扩张。上层和林下树木组成的比较表明，在低海拔地区，在没有火灾的情况下，持续演替，即用亚高山冷杉（Abies lasiocarpa）取代长叶松（Pinus contorta）。 contorta幼苗分布在比同一物种的上层树木更高的海拔处，这表明在变暖条件下有一定的上坡运动的潜力；P. 相反，白茎幼苗分布在样带的所有海拔高度。松属植物发生了严重的树木死亡。并且受到不成比例的影响。 albicaulis，由于区域性 Dendroctonus ponderosae（山松甲虫）爆发（2008-2012 年）。死亡事件与树木死亡前 2-3 年比平均条件更干燥密切相关。结论 20 世纪中叶，在已经茂密、老化的森林中，对干旱条件的敏感性不断上升，在最近的干旱期间，似乎增加了对甲虫引起的死亡的敏感性。研究区域的树种对全球变化压力源做出单独反应，全球变化压力源以复杂的方式作用于这些森林，导致生态交错带的变化和稳定。这项工作强调了演替、森林干扰和气候相关的生长反应之间的相互作用在驱动亚高山和林线环境中森林组成的变化。
QuestionsGlobal climate change is predicted to cause widespread shifts in the distribution and composition of forests, particularly in mountain environments where climate exerts strong controls on tree community arrangement. The upslope movement of vegetation has been observed in association with warming temperatures and is especially evident in ecotones—the transition zones between vegetation types. We explored the role of drought and tree mortality on recent changes in high‐elevation forests.LocationGreater Yellowstone Ecosystem, USA.MethodsWe established 19 forest demography plots along an elevational gradient spanning dominant high‐elevation vegetation types.ResultsTree establishment dates indicated the upslope movement ofPinus albicaulis(whitebark pine) treeline and ecotone shift from meadow to forest starting in the 1950s. An expansion of the growing season likely contributed to the upward expansion of the treeline. Comparisons between overstory and understory tree composition suggested ongoing succession in the absence of fire at lower elevations, namely the replacement ofPinus contorta(lodgepole pine) byAbies lasiocarpa(subalpine fir).P. contortaseedlings were distributed at higher elevations than overstory trees of the same species, suggesting some potential for upslope movement with warming conditions;P. albicaulisseedlings, conversely, were distributed throughout all elevations of the transect. Significant tree mortality occurred inPinusspp. and disproportionately affectedP. albicaulis, as a result of a regionalDendroctonus ponderosae(mountain pine beetle) outbreak (2008–2012). Mortality events were strongly associated with drier than average conditions 2–3 years prior to tree death.ConclusionRising sensitivity to arid conditions in the mid‐20th century amid already dense, aging forests appears to have increased susceptibility to beetle‐induced mortality during the most recent drought. Tree species in the study area responded individually to global change stressors, which acted on these forests in complex ways and led to both ecotone shifts and stability. This work highlights the interplay between succession, forest disturbances and climate‐related growth responses in driving forest compositional change in subalpine and treeline environments.