Menglin Su , Ke Yan , Xiangfu Wang , Jiaxin Jin , Yuanhui Li , Wenting Dong , Haikui Li , Jun Lu , Chuanchuan Zhao , Weifeng Wang
{"title":"Contrasting responses of water use efficiency to increasing aridity in alpine shrubs: A modelling perspective","authors":"Menglin Su , Ke Yan , Xiangfu Wang , Jiaxin Jin , Yuanhui Li , Wenting Dong , Haikui Li , Jun Lu , Chuanchuan Zhao , Weifeng Wang","doi":"10.1016/j.jhydrol.2024.131595","DOIUrl":null,"url":null,"abstract":"<div><p>Water use efficiency (WUE), which is strongly related to carbon and water cycles, is crucial for maintaining fragile and sensitive alpine ecosystems. An accurate assessment of the spatial and temporal variations in WUE among alpine shrubs under different aridity levels is essential for quantifying the carbon and water balance in alpine environments. We calibrated the Biome-BGC model using the parameter estimation (PEST) approach with one year of data from an eddy covariance tower and validated the model against three years of carbon–water flux and carbon storage data from 80 biomass sampling sites in Qinghai Province, China. We then simulated the carbon and water cycles of alpine shrubs in Qinghai Province from 1980 to 2019. Using meteorological data from the study area, we analyzed the spatiotemporal variations and factors influencing WUE in regions with different aridity levels. The results showed that after optimization using the PEST approach, the mean absolute error (MAE) and root mean square error (RMSE) of gross primary productivity (GPP) decreased by 0.58 and 1.05 g C m<sup>−2</sup> d<sup>−1</sup>, respectively, and those of evapotranspiration (ET) decreased by 0.41 and 0.77 mm d<sup>−1</sup>, respectively. Spatial distribution analysis revealed that the annual mean GPP and ET generally decreased from southeast to northwest in the order of humid, subhumid, semi-arid, arid, and hyper-arid climate regions. In other regions, WUE exhibited a biphasic trend with the aridity index, decreasing under severe dryness but increasing as aridity increased. The primary controlling factor in humid and sub-humid regions is the mean annual temperature, whereas in arid and semi-arid regions it is the mean annual precipitation. These findings are critical for improving the prediction of carbon sequestration and water-holding capacity of alpine shrublands under drought conditions.</p></div>","PeriodicalId":362,"journal":{"name":"Journal of Hydrology","volume":null,"pages":null},"PeriodicalIF":5.9000,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Hydrology","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0022169424009910","RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENGINEERING, CIVIL","Score":null,"Total":0}
引用次数: 0
Abstract
Water use efficiency (WUE), which is strongly related to carbon and water cycles, is crucial for maintaining fragile and sensitive alpine ecosystems. An accurate assessment of the spatial and temporal variations in WUE among alpine shrubs under different aridity levels is essential for quantifying the carbon and water balance in alpine environments. We calibrated the Biome-BGC model using the parameter estimation (PEST) approach with one year of data from an eddy covariance tower and validated the model against three years of carbon–water flux and carbon storage data from 80 biomass sampling sites in Qinghai Province, China. We then simulated the carbon and water cycles of alpine shrubs in Qinghai Province from 1980 to 2019. Using meteorological data from the study area, we analyzed the spatiotemporal variations and factors influencing WUE in regions with different aridity levels. The results showed that after optimization using the PEST approach, the mean absolute error (MAE) and root mean square error (RMSE) of gross primary productivity (GPP) decreased by 0.58 and 1.05 g C m−2 d−1, respectively, and those of evapotranspiration (ET) decreased by 0.41 and 0.77 mm d−1, respectively. Spatial distribution analysis revealed that the annual mean GPP and ET generally decreased from southeast to northwest in the order of humid, subhumid, semi-arid, arid, and hyper-arid climate regions. In other regions, WUE exhibited a biphasic trend with the aridity index, decreasing under severe dryness but increasing as aridity increased. The primary controlling factor in humid and sub-humid regions is the mean annual temperature, whereas in arid and semi-arid regions it is the mean annual precipitation. These findings are critical for improving the prediction of carbon sequestration and water-holding capacity of alpine shrublands under drought conditions.
水分利用效率(WUE)与碳和水循环密切相关,对于维持脆弱而敏感的高山生态系统至关重要。准确评估不同干旱程度下高山灌木水分利用效率的时空变化对于量化高山环境的碳水平衡至关重要。我们利用涡度协方差塔一年的数据,采用参数估计(PEST)方法校准了Biome-BGC模型,并根据中国青海省80个生物量采样点三年的碳-水通量和碳储量数据对模型进行了验证。然后,我们模拟了 1980 年至 2019 年青海省高山灌木的碳循环和水循环。利用研究地区的气象数据,我们分析了不同干旱程度地区的时空变化和影响水分利用效率的因素。结果表明,采用PEST方法优化后,总初级生产力(GPP)的平均绝对误差(MAE)和均方根误差(RMSE)分别减少了0.58和1.05 g C m-2 d-1,蒸散量(ET)的平均绝对误差和均方根误差分别减少了0.41和0.77 mm d-1。空间分布分析表明,按照湿润、亚湿润、半干旱、干旱和超干旱气候区的顺序,年均 GPP 和 ET 从东南向西北普遍下降。在其他地区,WUE 与干旱指数呈双相趋势,在严重干旱时减少,但随着干旱程度的增加而增加。湿润和亚湿润地区的主要控制因素是年平均气温,而干旱和半干旱地区的主要控制因素是年平均降水量。这些发现对于改进干旱条件下高山灌木林地碳封存和持水能力的预测至关重要。
期刊介绍:
The Journal of Hydrology publishes original research papers and comprehensive reviews in all the subfields of the hydrological sciences including water based management and policy issues that impact on economics and society. These comprise, but are not limited to the physical, chemical, biogeochemical, stochastic and systems aspects of surface and groundwater hydrology, hydrometeorology and hydrogeology. Relevant topics incorporating the insights and methodologies of disciplines such as climatology, water resource systems, hydraulics, agrohydrology, geomorphology, soil science, instrumentation and remote sensing, civil and environmental engineering are included. Social science perspectives on hydrological problems such as resource and ecological economics, environmental sociology, psychology and behavioural science, management and policy analysis are also invited. Multi-and interdisciplinary analyses of hydrological problems are within scope. The science published in the Journal of Hydrology is relevant to catchment scales rather than exclusively to a local scale or site.