Carilla Julieta, Aráoz Ezequiel, Foguet Javier, Casagranda Elvira, Halloy Stephan, Grau Alfredo
Instituto de Ecología Regional (IER), Universidad Nacional de Tucumán (UNT)- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Tucumán, Argentina.
Animal and Plant Health Directorate, Biosecurity, Ministry for Primary Insdustries, New Zealand, Ministry for Primary Industries, Wellington, New Zealand.
Front Plant Sci. 2023 Jan 20;13:1067096. doi: 10.3389/fpls.2022.1067096. eCollection 2022.
Mountain ecosystems are sensitive to climate fluctuations; however, the scarcity of instrumental data makes necessary the use of complementary information to study the effect of climate change on these systems. Remote sensing permits studying the dynamics of vegetation productivity and wetlands in response to climate variability at different scales. In this study we identified the main climate variables that control vegetation dynamics and water balance in Cumbres Calchaquíes, NW Argentina. For this, we built annual time series from 1986 to 2019 of Soil Adjusted Vegetation Index (SAVI, to quantify spare vegetation productivity), lake area, and snow-ice cover of peatlands, as indicators of mountain productivity and hydrology. We used a decompose function to explore trend, seasonality and random signal of the three-time series, and explored for significant changes in the mean value of consecutive periods. We used correlational analysis to explore their associations with climate records at local, regional, and global scales. The results showed that, SAVI and hydrological indicators presented different fluctuation patterns more pronounced since 2012, when they showed divergent trends with increasing SAVI and decreasing lake area and snow-ice cover. The three indicators responded differently to climate; SAVI increased in warmer years and lake area reflected the water balance of previous years. Snow-ice cover of peatlands was highly correlated with lake area. La Niña had a positive effect on lake area and snow-ice cover and a negative on SAVI, while El Niño had a negative effect on SAVI. Fluctuations of lake areas were synchronized with lake area in the nearby Argentinian puna, suggesting that climate signals have regional extent. The information provided by the three hydroclimate indicators is complementary and reflects different climate components and processes; biological processes (SAVI), physical processes (snow ice cover) and their combination (lake area). This study provides a systematic accessible replicable tool for mountain eco-hydrology long-term monitoring.
山地生态系统对气候波动敏感；然而，仪器数据的稀缺使得有必要利用补充信息来研究气候变化对这些系统的影响。遥感技术能够在不同尺度上研究植被生产力和湿地动态对气候变化的响应。在本研究中，我们确定了控制阿根廷西北部卡尔查基斯山脉植被动态和水平衡的主要气候变量。为此，我们构建了1986年至2019年的年度时间序列，包括土壤调整植被指数（SAVI，用于量化植被生产力）、湖泊面积和泥炭地的冰雪覆盖，作为山地生产力和水文状况的指标。我们使用分解函数来探索这三个时间序列的趋势、季节性和随机信号，并探究连续时期平均值的显著变化。我们使用相关分析来探究它们与当地、区域和全球尺度气候记录的关联。结果表明，自2012年以来，SAVI和水文指标呈现出不同的波动模式，且更为明显，当时它们呈现出相反的趋势，SAVI增加，而湖泊面积和冰雪覆盖减少。这三个指标对气候的响应各不相同；SAVI在较温暖的年份增加，湖泊面积反映了前几年的值。泥炭地的冰雪覆盖与湖泊面积高度相关。拉尼娜现象对湖泊面积和冰雪覆盖有积极影响，对SAVI有负面影响，而厄尔尼诺现象对SAVI有负面影响。湖泊面积的波动与附近阿根廷普纳地区的湖泊面积同步，这表明气候信号具有区域范围。这三个水文气候指标提供的信息具有互补性，反映了不同的气候组成部分和过程；生物过程（SAVI）、物理过程（冰雪覆盖）及其组合（湖泊面积）。本研究为山地生态水文学的长期监测提供了一个系统、可获取且可复制的工具。
