Smithsonian Environmental Research Center, Smithsonian Institution, Edgewater, Maryland, 21037, USA.
Tyson Research Center, Department of Biology, Washington University in St. Louis, Saint Louis, Missouri, 63130, USA.
Ecology. 2017 Oct;98(10):2513-2520. doi: 10.1002/ecy.1979.
Recent climate warming has led to asynchronous species migrations, with major consequences for ecosystems worldwide. In woody communities, localized microclimates have the potential to create feedback mechanisms that can alter the rate of species range shifts attributed to macroclimate drivers alone. Mangrove encroachment into saltmarsh in many areas is driven by a reduction in freeze events, and this encroachment can further modify local climate, but the subsequent impacts on mangrove seedling dynamics are unknown. We monitored microclimate conditions beneath mangrove canopies and adjacent open saltmarsh at a freeze-sensitive mangrove-saltmarsh ecotone and assessed survival of experimentally transplanted mangrove seedlings. Mangrove canopies buffered night time cooling during the winter, leading to interspecific differences in freeze damage on mangrove seedlings. However, mangrove canopies also altered biotic interactions. Herbivore damage was higher under canopies, leading to greater mangrove seedling mortality beneath canopies relative to saltmarsh. While warming-induced expansion of mangroves can lead to positive microclimate feedbacks, simultaneous fluctuations in biotic drivers can also alter seedling dynamics. Thus, climate change can drive divergent feedback mechanisms through both abiotic and biotic channels, highlighting the importance of vegetation-microclimate interactions as important moderators of climate driven range shifts.
最近的气候变暖导致了物种迁徙的不同步，这对全球的生态系统产生了重大影响。在木本植物群落中，局部小气候有可能产生反馈机制，从而改变仅由大气候驱动因素引起的物种分布范围变化的速度。在许多地区，红树林向盐沼的侵入是由冰冻事件减少驱动的，这种侵入可以进一步改变当地的气候，但随后对红树林幼苗动态的影响尚不清楚。我们在一个对冰冻敏感的红树林-盐沼生态交错带监测了红树林树冠下和相邻开阔盐沼的小气候条件，并评估了实验移植的红树林幼苗的存活率。红树林树冠在冬季缓冲了夜间降温，导致红树林幼苗的冰冻损伤存在种间差异。然而，红树林树冠也改变了生物相互作用。树冠下的食草动物的损害更高，导致树冠下的红树林幼苗死亡率高于盐沼。虽然由于气候变暖导致红树林的扩张会产生积极的小气候反馈，但生物驱动因素的同时波动也会改变幼苗动态。因此，气候变化可以通过非生物和生物途径驱动不同的反馈机制，凸显了植被-小气候相互作用作为气候驱动的分布范围变化的重要调节因素的重要性。
