Ibáñez Inés, Katz Daniel S W, Lee Benjamin R
School of Natural Resources and Environment, University of Michigan, Ann Arbor, MI, 48109, USA.
Oecologia. 2017 Jul;184(3):701-713. doi: 10.1007/s00442-017-3889-1. Epub 2017 Jun 1.
Predictions of plant responses to climate change are frequently based on organisms' presence in warmer locations, which are then assumed to reflect future performance in cooler areas. However, as plant life stages may be affected differently by environmental changes, there is little empirical evidence that this approach provides reliable estimates of short-term responses to global warming. Under this premise, we analyzed 8 years of early recruitment data, seed production and seedling establishment and survival, collected for two tree species at two latitudes. We quantified recruitment to a wide range of environmental conditions, temperature, soil moisture and light, and simulated recruitment under two forecasted climatic scenarios. Annual demographic transitions were affected by the particular conditions taking place during their onset, but the effects of similar environmental shifts differed among the recruitment stages; seed production was higher in warmer years, while seedling establishment and survival peaked during cold years. Within a species, these effects also varied between latitudes; increasing temperatures at the southern location will have stronger detrimental effects on recruitment than similar changes at the northern locations. Our simulations illustrate that warmer temperatures may increase seed production, but they will have a negative effect on establishment and survival. When the three early recruitment processes were simultaneously considered, simulations showed little change in recruitment dynamics at the northern site and a slight decrease at the southern site. It is only when we considered these three stages that we were able to assess likely changes in early recruitment under the predicted conditions.
对植物对气候变化反应的预测通常基于生物体在较温暖地区的存在情况，然后假定这些情况能反映其在较凉爽地区的未来表现。然而，由于植物的生命阶段可能受到环境变化的不同影响，几乎没有实证证据表明这种方法能为全球变暖的短期反应提供可靠的估计。在此前提下，我们分析了在两个纬度对两种树种收集的长达8年的早期补充数据、种子产量以及幼苗建立和存活情况。我们对广泛的环境条件、温度、土壤湿度和光照下的补充情况进行了量化，并在两种预测气候情景下模拟了补充情况。年度种群统计学转变受到其开始时发生的特定条件的影响，但类似环境变化的影响在补充阶段之间有所不同；温暖年份的种子产量较高，而幼苗建立和存活在寒冷年份达到峰值。在一个物种内，这些影响在不同纬度之间也有所不同；南部地区温度升高对补充的不利影响将比北部地区类似变化的影响更强。我们的模拟表明，温度升高可能会增加种子产量，但会对建立和存活产生负面影响。当同时考虑三个早期补充过程时，模拟显示北部地点的补充动态变化不大，而南部地点略有下降。只有当我们考虑这三个阶段时，我们才能评估在预测条件下早期补充可能发生的变化。
