The tropical dry forests of NW Peru are heavily shaped by the El Niño Southern Oscillation (ENSO), where especially El Niño brings rain to arid to semi‐arid areas. However, the resulting effects on biodiversity patterns remain largely unknown as well as the effect of environmental variables on the floristic composition under varying rainfall patterns. Therefore, we studied the spatio‐temporal effects of different ENSO episodes on floristic biodiversity along a climatic gradient ranging from the coastal desert to the Andean foothills. We sampled 50 vegetation plots in four years representing different ENSO episodes. To highlight the spatio‐temporal changes in floristic composition and beta diversity across ENSO episodes, we predicted ordination scores with a Generalized Additive Model. We applied variation partitioning to test if topographic or edaphic variables gained in importance during more humid ENSO episodes. Additionally, we executed an irrigation–fertilization experiment to quantify the beneficial effects of the water–nutrient interaction under different simulated ENSO rainfall scenarios. Plant species richness increased under humid conditions during the humid La Niña (2012) and the moderate El Niño (2016), and slightly decreased under the very humid conditions during the coastal El Niño (2017). The spatial prediction revealed that specific vegetation formations became more pronounced with increasing water input, but that a large water surplus led to the disruption of the strict order along the climatic gradient. Edaphic and topographic variables gained in importance with increased water availability (2012 and 2016), however, this effect was not further amplified under very wet conditions (2017). The experiment showed that plant cover under Super Niño conditions was three times higher when fertilized. Overall, our spatial predictions concede detailed insights into spatio‐temporal ecosystem dynamics in response to varying rainfall caused by different ENSO episodes while the results of the experiment can support farmers regarding a sustainable agrarian management.

中文翻译：

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秘鲁西北部ENSO陆地核心区域沿气候梯度的植物生物多样性的监测和预测测绘

秘鲁西北部的热带干旱森林受到厄尔尼诺南方涛动（ENSO）的强烈影响，特别是厄尔尼诺现象使干旱和干旱地区的降雨增加。然而，由此产生的对生物多样性格局的影响以及在变化的降雨格局下环境变量对植物组成的影响仍然未知。因此，我们研究了从沿海沙漠到安第斯山麓丘陵的气候梯度，不同ENSO事件对植物多样性的时空影响。我们在四年中对代表不同ENSO事件的50个植被地块进行了采样。为了突出ENSO发作期间植物区系组成和β多样性的时空变化，我们使用广义加性模型预测了配位分数。我们应用了变分划分法来测试在ENSO更加潮湿的情况下，地形或前卫变量是否变得越来越重要。此外，我们进行了灌溉施肥实验，以量化在不同模拟ENSO降雨情景下水与养分相互作用的有益影响。在潮湿的拉尼娜（2012）和中度厄尔尼诺（2016）期间，植物种类的丰富度在潮湿的条件下增加，而在沿海的厄尔尼诺（2017）的湿润条件下，植物物种的丰富度略有下降。空间预测表明，随着水输入的增加，特定的植被形成变得更加明显，但是大量的水过剩导致了沿气候梯度的严格顺序的破坏。随着可用水量的增加（2012年和2016年），深层和地形变量变得越来越重要，但是，在非常潮湿的条件下（2017年）这种影响并未得到进一步放大。实验表明，施肥后在超级尼诺条件下的植物覆盖率要高三倍。总体而言，我们的空间预测让人们对时空生态系统动态变化的详细见解，以应对因ENSO事件不同引起的降雨变化，而实验结果可以为农民提供可持续的土地管理方面的支持。