分类： 地球科学 >> 地理学 提交时间： 2020-12-17 合作期刊: 《干旱区研究》
摘要：干旱区养分相对匮乏，雨水流经冠层后有效的养分输入对干旱区植物的生长发育意义重大。本文通过对古尔班通古特沙漠南缘主要建群种梭梭（Haloxylon ammodendron）与白梭梭（Haloxylon persicum）降雨过程中冠层养分的研究，分析树干茎流、穿透雨以及雨水中碳、氮、磷的浓度差异，明确雨水流经植物冠层后各离子的变化特征。结果表明，雨水在经过梭梭与白梭梭冠层后总有机碳（TOC）、总氮（TN）浓度增加显著，总磷（TP）增加并不显著。铵态氮（NH4+-N）浓度变化与TN基本一致，硝态氮（NO3--N）、亚硝态氮（NO2--N）浓度差异性不完全显著；其中，树干茎流有机氮（TON）的比例最高，在TN中所占比例始终大于50%。对于不同养分输入的平均浓度，除TP、NO3--N外，其他离子均有所增加；TP、NO3--N、NO2--N浓度较低，在树干茎流、穿透雨以及雨水中的变异系数较大。
分类： 环境科学技术及资源科学技术 >> 环境科学技术基础学科 提交时间： 2019-10-26 合作期刊: 《干旱区科学》
摘要：Soil moisture is critical for vegetation growth in deserts. However, detailed data regarding the soil moisture distribution in space and time in the Gurbantunggut Desert of China have not yet been reported. In this study, we conducted a series of in situ observation experiments in a fixed sand dune at the southern edge of the Gurbantunggut Desert from February 2014 to October 2016, to explore the spatio-temporal variation of soil moisture content, investigate the impact of Haloxylon ammodendron (C. A. Mey.) Bungeon soil moisture content in its root zone, and examine the factors influencing the soil moisture spatial pattern. One-way analysis of variance, least significant difference tests and correlation analysis were used to analyze the data. The results revealed that the soil moisture content exhibited annual periodicity and the temporal variation of soil moisture content throughout a year could be divided into three periods, namely, a moisture-gaining period, a moisture-losing period and a moisture-stable period. According to the temporal and spatial variability, the 0–400 cm soil profile could be divided into two layers: an active layer with moderate variability and a stable layer with weak variability. The temporal variability was larger than the spatial variability in the active layer, and the mean profile soil moisture content at different slope positions displayed the trend of decreasing with increasing relative height and mainly followed the order of interdune area>west and east slopes>slope top. The mean profile soil moisture content in the root zone of dead H. ammodendron individuals was significantly higher than that in the root zones of adult and young individuals, while the soil moisture content in the root zone of adult individuals was slightly higher than that in the root zone of young individuals with no significant difference. The spatial pattern of soil moisture was attributable to the combined effects of snowfall, vegetation and soil texture, whereas the effects of rainfall and evaporation were not significant. The findings may offer a foundation for the management of sandy soil moisture and vegetation restoration in arid areas.
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