Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China; Alxa Desert Eco-hydrology Experimental Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China.
Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China; Alxa Desert Eco-hydrology Experimental Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China.
J Environ Manage. 2023 Oct 15;344:118416. doi: 10.1016/j.jenvman.2023.118416. Epub 2023 Jun 16.
Knowledge on relationship and determinants of water and carbon dioxide (CO) exchange is crucial to land managers and policy makers especially for the desertified land restoration. However, there remains highly uncertain in terms of water use and carbon sequestration for artificial plantation in desert. Here, continuous water and carbon fluxes were measured using eddy covariance (EC) in conjunction with hydrometeorological measurements over an artificial C4 shrub, Haloxylon ammodendron (C. A. Mey.) Bunge, from July 2020 to 2021 in Tengger Desert, China. Throughout 2021, evapotranspiration (ET) was 189.5 mm, of which 85% (150 mm) occurred during growing season, that was comparable with the summation of precipitation (132.2 mm), dew (33.5 mm) and potential other sources (e.g. deep subsoil water). This ecosystem was a strong carbon sink with net ecosystem production (NEP) up to 446.4 g C m yr, much higher than surrounding sites. Gross primary production (GPP, 598.7 g C m yr) in this shrubland was comparable with that of other shrublands, whereas ecosystem respiration (Re, 152.3 g C m yr) was lower. Random Forest showed that environmental factors can explain 71.56% and 80.07% variation of GPP and ET, respectively. Interestingly, environmental factors have divergent effect on water and carbon exchange, i.e., soil hydrothermic factors (soil moisture content and soil temperature) determine the magnitude and seasonal pattern of ET and Re, while aerodynamics factors (net radiation, atmospheric temperature and wind speed) determine GPP and NEP. As such, divergent response of abiotic factors resulted in the decoupling of water and carbon exchange. Our results suggest that H. ammodendron is a suitable species for large-scale afforestation in dryland given its low water use but high carbon sequestration. Therefore, we infer that artificial planting H. ammodendron in dryland could provide an opportunity for climate change mitigation, and the long-term time series data is needed to confirm its sustainable role of carbon sequestration in the future.
在荒漠地区进行人工种植时，有关水和二氧化碳（CO）交换的关系和决定因素的知识对土地管理者和政策制定者至关重要，特别是在荒漠恢复方面。然而，在人工种植的情况下，水的利用和碳的固存仍然存在很大的不确定性。在这里，我们通过涡度相关（EC）技术与水文气象测量相结合，对 2020 年 7 月至 2021 年在中国腾格里沙漠的人工 C4 灌木梭梭（Haloxylon ammodendron（C. A. Mey.）Bunge）进行了连续的水碳通量测量。在 2021 年期间，蒸散量（ET）为 189.5mm，其中 85%（150mm）发生在生长季节，与降水量（132.2mm）、露水（33.5mm）和其他潜在来源（如深层土壤水）的总和相当。这个生态系统是一个强大的碳汇，净生态系统生产（NEP）高达 446.4g C m yr，远高于周围的站点。该林地的总初级生产力（GPP，598.7g C m yr）与其他林地相当，而生态系统呼吸（Re，152.3g C m yr）较低。随机森林表明，环境因素可以分别解释 GPP 和 ET 变化的 71.56%和 80.07%。有趣的是，环境因素对水和碳交换的影响不同，即土壤水热因素（土壤含水量和土壤温度）决定了 ET 和 Re 的大小和季节性模式，而空气动力学因素（净辐射、大气温度和风速）决定了 GPP 和 NEP。因此，非生物因素的不同响应导致了水和碳交换的解耦。我们的结果表明，鉴于梭梭的低耗水量但高碳固存能力，它是在干旱地区进行大规模造林的合适物种。因此，我们推断在干旱地区人工种植梭梭为应对气候变化提供了一个机会，需要长期的时间序列数据来确认其未来在碳固存方面的可持续作用。
