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  • Soil evolution along an alluvial-loess transect in the Herat Plain, western Afghanistan

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2022-11-12 合作期刊: 《干旱区科学》

    摘要:

  • Carbon inputs regulate the temperature sensitivity of soil respiration in temperate forests

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2022-10-14 合作期刊: 《干旱区科学》

    摘要:

  • 黄土高原丘陵区典型植物群落土壤粒径分布特征

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2022-08-09 合作期刊: 《干旱区地理》

    摘要:为探究黄土高原丘陵区不同植物群落的土壤粒径分布特征。选取草地、山杏纯林、油松纯林和油松山杏混交林0~200 cm土壤为研究对象,采用激光衍射技术测定土壤样品粒度组成,计算土壤粒度参数与分形维数,绘制粒度频率曲线。结果表明:(1)研究区土壤属粉壤土,粉粒含量约占总体的56.58%~71.67%,砂粒约占21.37%~38.71%,黏粒约占3.55%~6.96%。(2)各植物群落内土壤粒度组成随土层深度增加分布较为均一,粒径分布整体分选性均较差,呈极正偏度,峰态尖窄,粒度频率曲线为双峰型,曲线波峰一致。不同植物群落土壤粒径分布差异主要集中在土壤表层0~20 cm(P<0.05)。(3)草地、山杏纯林、油松纯林和油松山杏混交林0~200 cm土壤平均分形维数分别为2.63、2.60、2.61、2.58。分形维数与黏粒含量具有极显著正相关关系(P<0.05),其中,草地土壤分形维数与黏粒的相关性最强。总体来看,黄土高原丘陵区草地土壤粒径分布特征显著优于人工林,本研究结果可为黄土高原的生态重建工作提供理论依据。

  • 不同初始盐分浓度下土壤盐结皮的形成过程 及其对蒸发的影响机理

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2022-08-08 合作期刊: 《干旱区地理》

    摘要:土壤盐结皮对土壤水文过程具有重要影响,初始盐分浓度(Initial salt concentration, ISC)的差异会对盐结皮的形成过程产生不同程度的影响,从而导致土壤蒸发的差异。但目前不同ISC下盐结皮形成过程对土壤蒸发的影响机理尚不明确。因此,通过试验模拟与理论分析相结合,动态监测及分析不同ISC下砂土的盐结皮形成、蒸发、土壤表面温度动态变化过程,以期阐明不同ISC下盐结皮形成过程及其对土壤蒸发的影响机理。结果表明:ISC越高,盐结皮在土壤表面出现的时间越早,覆盖率越大,且在同样光照强度和光照时间条件下土表温度增幅越小,蒸发量也越小;对数函数能较好地拟合不同ISC与累积蒸发量之间的关系(R2>0.90);随着ISC的增加,盐结皮对土壤蒸发抑制效率从24.14%(10 g·L-1)增大到71.99%(250 g·L-1)。ISC会显著影响盐结皮形成的过程,并通过影响土表温度的变化进而导致土壤蒸发出现巨大差异。

  • 湿地土壤气体排放对水位变化响应的持续性动态特征

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2022-06-08 合作期刊: 《干旱区地理》

    摘要:

    为探索湿地水位变化与土壤气体排放之间的关系,对黄河中游芦苇湿地进行了半注水和满注水样地处理后的动态监测,对比了7 d水位变化过程中土壤气体排放差异。结果表明:注水造成了土壤CO2排放速率的显著差异;随土壤温度上升,H2O、CO2、H2S排放速率都有上升趋势(满注水样地的H2O除外);半注水和满注水造成的影响,H2O排放速率表现为趋同-异步-消失的特征,在注水前期(63.73 h)半注水和满注水差异基本一致,后期差异较大,直至125.64 h后注水的影响才消失,总体分别造成H2O排放总量76.3%和31.3%的增加;CO2排放速率表现为异步-趋同的特征,注水初期环境的改变造成CO2排放的一致减少,37.69~68.66 h二者出现明显差异,68.66~125.64 h水位虽然恢复,但差异仍然存在,注水分别造成CO2排放总量50.1%和43.2%的减少;H2S排放速率表现为无变化-异步-无变化的特征,总体造成H2S排放总量42.3%和32.3%的增加。研究追踪了水位上升后土壤H2O、CO2和H2S排放速率变化的动态过程,其影响具有异步性和持续性的特点,CO2排放速率表现出较长的响应周期。研究结果对于河流湿地生态功能研究具有重要意义,湿地土壤气体排放对水位变化的响应滞后意味着对湿地生态功能的重要影响,其波动过程需要更长时段的精准研究。

  • Effects of mixed-based biochar on water infiltration and evaporation in aeolian sand soil

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2022-05-09 合作期刊: 《干旱区科学》

    摘要:

    Abstract: Aeolian sandy soil in mining areas exhibits intense evaporation and poor water retention capacity. This study was designed to find a suitable biochar application method to improve soil water infiltration and minimize soil water evaporation for aeolian sand soil. Using the indoor soil column method, we studied the effects of three application patterns (A (0–20 cm was a mixed sample of mixed-based biochar and soil), B (0–10 cm was a mixed sample of mixed-based biochar and soil and 10–20 cm was soil), and C (0–10 cm was soil and 10–20 cm was a mixed sample of mixed-based biochar and soil)), four application amounts (0% (control, CK), 1%, 2%, and 4% of mixed-based biochar in dry soil), and two particle sizes (0.05–0.25 mm (S1) and <0.05 mm (S2)) of mixed-based biochar on water infiltration and evaporation of aeolian sandy soil. We separately used five infiltration models (the Philip, Kostiakov, Horton, USDA-NRCS (United States Department of Agriculture-Natural Resources Conservation Service), and Kostiakov-Lewis models) to fit cumulative infiltration and time. Compared with CK, the application of mixed-based biochar significantly reduced cumulative soil water infiltration. Under application patterns A, B, and C, the higher the application amount and the finer the particle size were, the lower the migration speed of the wetting front. With the same application amount, cumulative soil water infiltration under application pattern A was the lowest. Taking infiltration for 10 min as an example, the reductions of cumulative soil water infiltration under the treatments of A2%(S2), A4%(S1), A4%(S2), A1%(S1), C2%(S1), and B1%(S1) were higher than 30%, which met the requirements of loess soil hydraulic parameters suitable for plant growth. The five infiltration models well fitted the effects of the treatments of application pattern C and S1 particle size (R2>0.980), but the R2 values of the Horton model exceeded 0.990 for all treatments (except for the treatment B2%(S2)). Compared with CK, all other treatments reduced cumulative soil water infiltration, except for B4%(S2). With the same application amount, cumulative soil water evaporation difference between application patterns A and B was small. Treatments of application pattern C and S1 particle size caused a larger reduction in cumulative soil water evaporation. The reductions in cumulative soil water evaporation under the treatments of C4%(S1), C4%(S2), C2%(S1), and C2%(S2) were over 15.00%. Therefore, applying 2% of mixed-based biochar with S1 particle size to the underlying layer (10–20 cm) could improve soil water infiltration while minimizing soil water evaporation. Moreover, application pattern was the main factor affecting soil water infiltration and evaporation. Further, there were interactions among the three influencing factors in the infiltration process (application amount×particle size with the most important interaction), while there were no interactions among them in the evaporation process. The results of this study could contribute to the rational application of mixed-based biochar in aeolian sandy soil and the resource utilization of urban and agricultural wastes in mining areas.

  • Variation of soil physical-chemical characteristics in salt-affected soil in the Qarhan Salt Lake, Qaidam Basin

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2022-03-24 合作期刊: 《干旱区科学》

    摘要:

    Soil salinization has adverse effects on the soil physical-chemical characteristics. However, little is known about the changes in soil salt ion concentrations and other soil physical-chemical characteristics within the Qarhan Salt Lake and at different soil depths in the surrounding areas. Here, we selected five sampling sites (S1, S2, S3, S4, and S5) alongside the Qarhan Salt Lake and in the Xidatan segment of the Kunlun Mountains to investigate the relationship among soil salt ion concentrations, soil physical-chemical characteristics, and environmental variables in April 2019. The results indicated that most sites had strongly saline and very strongly saline conditions. The main salt ions present in the soil were Na+, K+, and Cl–. Soil nutrients and soil microbial biomass (SMB) were significantly affected by the salinity (P<0.05). Moreover, soil salt ions (Na+, K+, Ca2+, Mg2+, Cl–, CO32–, SO42–, and HCO3–) were positively correlated with electrical conductivity (EC) and soil water content (SWC), but negatively related to altitude and soil depth. Unlike soil salt ions, soil nutrients and SMB were positively correlated with altitude, but negatively related to EC and SWC. Moreover, soil nutrients and SMB were negatively correlated with soil salt ions. In conclusion, soil nutrients and SMB were mainly influenced by salinity, and were related to altitude, soil depth, and SWC in the areas from the Qarhan Salt Lake to the Xidatan segment. These results imply that the soil quality (mainly evaluated by soil physical-chemical characteristics) is mainly influenced by soil salt ions in the areas surrounding the Qarhan Salt Lake. Our results provide an accurate prediction of how the soil salt ions, soil nutrients, and SMB respond to the changes along a salt gradient. The underlying mechanisms controlling the soil salt ion distribution, soil nutrients, and SMB in an extremely arid desert climate playa should be studied in greater detail in the future.

  • Integrating multiple electromagnetic data to map spatiotemporal variability of soil salinity in Kairouan region, Central Tunisia

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2022-03-15 合作期刊: 《干旱区科学》

    摘要:

    Soil salinization is a major problem affecting soils and threatening agricultural sustainability in arid and semi-arid regions, which makes it necessary to establish an efficient strategy to manage soil salinity and confront economic challenges that arise from it. Saline soil recovery involving drainage of shallow saline groundwater and the removal of soil salts by natural rainfall or by irrigation are good strategies for the reclamation of salty soil. To develop suitable management strategies for salty soil reclamation, it is essential to improve soil salinity assessment process/mechanism and to adopt new approaches and techniques. This study mapped a recovered area of 7200 m2 to assess and verify variations in soil salinity in space and time in Kairouan region in Central Tunisia, taking into account the thickness of soil materials. Two electromagnetic conductivity meters (EM38 and EM31) were used to measure the electrical conductivity of saturated soil-paste extract (ECe) and apparent electrical conductivity (ECa). Multiple linear regression was established between ECe and ECa, and it was revealed that ECa-EM38 is optimal for ECe prediction in the surface soils. Salinity maps demonstrated that the spatial structure of soil salinity in the region of interest was relatively unchanged but varied temporally. Variation in salinity at the soil surface was greater than that at a depth. These findings can not only be used to track soil salinity variations and their significance in the field but also help to identify the spatial and temporal features of soil salinity, thus improving the efficiency of soil management.

  • 努尔苏丹樟子松人工林土壤粒度组成特征研究

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2022-02-11 合作期刊: 《干旱区地理》

    摘要:

    为了揭示努尔苏丹不同林龄樟子松人工林对土壤粒度组成的影响,通过野外采样与室内分析相结合,分析了努尔苏丹周边不同林龄樟子松人工林土壤粒度与分形维数特征,研究了分形维数与土壤特性之间的关系。结果表明:(1)研究区土壤粒度组成以粉粒为主,砂粒次之,黏粒最少, 樟子松人工林的种植能够显著提升土壤表层细颗粒物质含量。不同林龄人工林深层土壤颗粒量差异不显著。种植樟子松人工林对土壤粒度的影响主要在表层区域。(2)土壤分形维数变化在 2.059~2.569之间,在人工林生长过程中分形维数呈现先增大后减小的趋势,并在种植年限为15 a 时达到最大。土壤分形维数与黏粒、粉粒具有正相关性,20 μm粒径是反映研究区人工林土壤分形维数的临界粒径。(3)研究区土壤分形维数与土壤有机质、全氮含量呈极显著正相关关系,土壤分形维数可以用来评价土壤的养分状况。研究结果可以为努尔苏丹人工林建设和生态恢复提供理
    论依据。

  • 亚寒带荒漠草原不同树种人工林土壤生态化学计量特征

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2021-09-14 合作期刊: 《干旱区研究》

    摘要:为了阐明亚寒带荒漠草原不同树种人工林间土壤养分含量及生态化学计量特征的差异,通过野外调查与室内分析相结合的方法,在哈萨克斯坦首都努尔苏丹选取种植白桦、樟子松、梣叶槭3种不同树种,林龄为11 a的亚寒带荒漠草原人工林为研究对象,以裸地为对照,对其土壤养分含量及其生态化学计量特征进行了分析。结果表明:(1)土壤养分含量受树种的影响,但不同树种间生态化学计量特征差异不显著。(2)种植人工林后,不同树种人工林土壤有机碳与全氮含量均显著增加,针叶林与阔叶林土壤表层有机C、全N含量差异显著。(3)土壤C、N、P含量呈极显著正相关关系,C含量是C:N、C:P的控制因子,N含量是N:P的控制因子。研究区种植人工林后,虽然土壤养分含量显著增加,但是总体含量仍小于全球平均水平,当地土壤养分仍处于匮乏状态。N是该地区养分循环和植物生长的限制性因素,在人工林生长过程中适当施用氮肥,可加快人工林生长和生态恢复进程。本研究可为哈萨克斯坦首都努尔苏丹的人工林建设和持续经营管理提供科学依据。

  • 水分胁迫对设施延迟栽培葡萄根际土壤 有机氮及土壤酶活性的影响

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2021-09-14 合作期刊: 《干旱区研究》

    摘要:为探讨不同水分胁迫条件下设施栽培葡萄根际土壤基本理化性质与有机氮组分及土壤酶活性的变化规律,并分析三者之间的相关关系,为甘肃河西地区设施延迟栽培葡萄制定合理的胁迫灌溉模式提供一定的参考依据。采用水分胁迫单因素完全随机试验设计,运用Bremner法测定着色成熟期葡萄根际土层中有机氮组分含量及土壤基本理化性质、全生育期土壤酶活性在不同水分胁迫(中度W1、轻度W2、充分供水W3)下的变化特征。结果表明:(1)全生育期中度和轻度水分胁迫对设施延迟栽培葡萄根际土壤全氮、铵态氮、全磷、有机质以及有机碳无显著影响,却降低了葡萄根际土壤微生物生物量碳、氮含量;新梢生长期和果实膨大期土壤硝态氮和速效磷含量分别为12.06 mg·kg-1和28.88 mg·kg-1,显著低于充分供水处理。(2)中度和轻度水分胁迫对葡萄全生育期根际土壤过氧化氢酶活性无显著性影响,而对果实膨大期和着色成熟期的脲酶、蔗糖酶含量均呈现不同程度的抑制效果。(3)各处理有机氮组分的含量大小顺序为非酸解态氮>酸解氨基酸态氮>酸解铵态氮>酸解未知态氮>酸解氨基糖态氮;轻度和中度水分胁迫均有助于葡萄根际土壤酸解总氮的积累,比对照分别提高21.16%和10.34%。(4)相关分析表明,蔗糖酶与生物量碳呈显著正相关;RDA分析显示硝态氮、铵态氮为影响土壤有机氮组分变化的最主要环境因子,全氮次之。

  • 早播及耕作措施对黄土高原半干旱区春小麦土壤氮 磷元素的影响

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2021-09-14 合作期刊: 《干旱区研究》

    摘要:为探讨早播及耕作措施对农田生态系统土壤氮磷元素影响规律,对黄土高原半干旱区早播、正常播下不同耕作措施[传统耕作(T)、传统耕作+秸秆还田(TS)、免耕(NT)、免耕+秸秆覆盖(NTS)]春小麦(Triticum aestivum)生育期0~40 cm土壤进行分析,以正常播种传统耕作春小麦为对照,研究早播及耕作措施对春小麦土壤氮磷元素的影响。结果表明:(1)不同处理下春小麦土壤N素(TN、NO-3 -N、NH+4 -N)、P素(TP)含量均具有表聚性特征,其土壤N∶P均值(1.713)低于全国平均值(5.2),同时其变异水平系数处于26.99%~77.28%,属中等变异水平;(2)全生育期0~40 cm土层,早播春小麦土壤TN、NH+4 -N含量及N∶P均值显著低于正常播23.1%~32.5%,不利于土壤TN、NH+4 -N含量积累,而NO-3 -N含量及NO-3 -N∶N均值显著高于正常播30.5%、41.5%,有助于土壤NO-3 -N含量的固存,同时早播处理下土壤TP含量整体高于正常播处理;(3)秸秆覆盖措施(NTS、TS)下土壤TN、TP含量高于NT、T,但速效氮(NO-3 -N、NH+4 -N)养分含量表现相反;(4)不同处理下春小麦土壤TP含量在生育期间趋于稳定,而N素含量在分蘖期及开花期变化较显著。因此,选择适宜播种时间及耕作管理措施有助于提高该区作物土壤N、P元素的积累转化效率,加快发展黄土高原半干旱区农田生态系统恢复进程。

  • 锡林郭勒草原土壤有机碳分布特征及其影响因素

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2021-09-14 合作期刊: 《干旱区研究》

    摘要:土壤有机碳是土壤养分评测和质量分析的重要指标之一,研究不同草原类型土壤有机碳的空间分布规律有利于草地的生态恢复和土地的合理利用。以锡林郭勒草原为研究对象,运用克里格插值法、相关性分析法、一元线性回归法和主成分分析法探讨土壤有机碳的空间分异规律,以期揭示不同影响因素对草原土壤有机碳的影响程度。结果表明:(1)在草甸草原中,土壤有机碳含量在0~10 cm、20~30 cm、40~50 cm土层的含量依次为23.28 g·kg-1、12.71 g·kg-1、9.28 g·kg-1;在典型草原中,含量变化依次为16.75 g·kg-1、10.75 g·kg-1、7.20 g·kg-1;在荒漠草原中,含量依次为1.62 g·kg-1、2.00 g·kg-1、1.73 g·kg-1。表明草甸和典型草原土壤有机碳含量随土壤深度增加而逐渐降低,而荒漠草原不同土层间无显著性差异。(2)不同草原类型对土壤有机碳含量的影响程度不同,对于同一土层深度,基本表现为草甸草原>典型草原>荒漠草原。水平方向上有机碳含量与植被盖度分布相一致,呈由东南向西北逐渐递减的趋势。(3)在对影响因素的分析中,土壤有机碳与海拔、气温、pH均呈极显著负相关关系(P<0.01),与降水、土壤含水量、速效氮、速效磷呈极显著正相关关系(P<0.01),与坡度、坡向、速效钾无明显相关性关系(P>0.05)。(4)影响土壤有机碳的主要因子为速效氮、降水量和气温,次要因子为土壤含水量和速效钾,因此,应注重对不同草原氮素的摄入以及水热条件的把控。

  • 祁连山南坡不同土地利用方式下土壤碳氮含量及通径分析

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2021-09-14 合作期刊: 《干旱区研究》

    摘要: 以祁连山南坡4种土地利用类型为研究对象,采用野外采样、实验室分析与单因素方差分析方法对不同土地利用方式下浅层(0~20 cm)和深层(20~50 cm)土壤TC(全碳)、TN(全氮)含量及差异显著性进行分析,使用通径分析方法揭示环境因子对土壤TC、TN的直接和间接作用效应。结果表明:(1)环境因子间相互作用,共同影响土壤碳氮含量。直接作用效应:土壤碳氮相互作用显著,pH对土壤碳氮含量直接作用较小。间接作用效应:土壤含水量(SWC)主要通过TN对浅层土壤TC含量起间接正效应,而pH通过TN对深层土壤TC含量起间接负效应。温度(T)主要通过降水(P)对浅层土壤TN含量起间接负效应,而容重(Pb)通过TC对深层土壤TN含量起间接负效应。(2)土壤碳氮含量具有明显的“表聚作用”。随土层深度的增加,土壤碳氮含量呈减少趋势。林地土壤碳氮含量最高,显著高于草地和耕地(P<0.05),但与灌丛差异不显著(P>0.05),研究区土壤氮含量较高,可为研究区植被生长提供较为充足的氮素养分元素。(3)土壤碳氮含量受自然环境和人类活动综合影响。

  • 民勤绿洲边缘阻沙带表层土壤粒度空间分布特征

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2021-09-14 合作期刊: 《干旱区研究》

    摘要:土壤粒度是风沙活动的重要表征参数。通过野外调查与室内测试,分析了不同空间分布防风固沙林表层土壤粒度的空间分布特征,旨在评价民勤绿洲边缘阻沙带防风固沙功能。结果表明:(1)坝区梭梭-沙拐枣-沙蒿-沙米固沙林表层土壤粒度组成以细砂、中砂、极细砂为主,分别占33.47%、26.08%、18.18%;泉山区白刺+沙蒿+五星蒿固沙林表层土壤粒度组成以细砂、粉粒和极细砂为主,分别占29.62%、21.17%、18.87%;湖区白刺-芦苇-猪毛菜固沙林表层土壤粒度组成以细砂、粉粒和极细砂为主,分别占36.66%、27.98%、22.83%。(2)平均粒径,坝区(2.55Φ)>泉山区(3.5 Φ)>湖区(3.94 Φ),分选性,坝区(1.58 Φ)较差,湖区(2.10 Φ)和泉山区(2.29 Φ)很差。(3)泉山区、湖区表层土壤粒度频率曲线为双峰型,坝区为单峰型,偏度均为极正偏态,峰度表现为很窄。粒度累计分布曲线反映出坝区风沙活动较泉山区、湖区频繁、强烈。阻沙带荒漠植被群落物种组成决定着其防风固沙功能的大小,进而影响其表层土壤的粒度分布特征。建议阻沙带生态防护体系修复时应注重选择固沙能力强的造林树种。

  • 干旱区耕地质量等级评价及土壤养分与盐渍化的分析研究 ——以民勤绿洲为例

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2021-04-14 合作期刊: 《干旱区地理》

    摘要: 为整体掌握民勤绿洲耕地质量、土壤养分以及盐渍化状况等,充分利用县域耕地资源,分 析研究民勤绿洲耕地质量等级划分及其耕地土壤养分和盐渍化现状,为及时准确掌握绿洲耕地地 力状况提供科学依据,同时为绿洲耕地土壤养分、盐渍化障碍提供改良措施。基于农业农村部《耕 地质量调查监测与评价办法》(农业部 2016 年第 2 号)和《耕地质量等级》国家标准(GB/T33469- 2016)的相关要求,构建民勤绿洲县域评价体系,通过综合运用空间分析、模糊数学、层次分析和综 合指数等方法,对民勤绿洲耕地质量等级进行综合评价。结果表明:(1)民勤绿洲耕地质量平均等 级为 3.26 等;分布有一至七等级地,八、九、十等级地没有分布;以三、四等级地为民勤绿洲耕地的 主要等级分布,面积占比分别为 31.63%、28.27%。泉山区中部和坝区灌溉农业区多分布一、二等级 地。湖区灌溉区多分布三、四等地。在绿洲边缘带较多分布五、六、七等地。(2)民勤绿洲耕地土壤 有机质平均含量在 10.00~15.00 g·kg-1 之间,全氮平均含量在 0.50~1.00 g·kg-1 之间,总体处于较低水 平。有效磷和速效钾总体处于中等水平。昌宁区、泉山区与坝区交界东北部以及湖区镇(昌宁镇、 东湖镇、南湖镇、泉山镇、西渠镇)耕地土壤养分平均含量较均低。(3)民勤绿洲盐渍化耕地的面积 为 32240.36 hm2,占民勤绿洲耕地总面积的 30.09%;主要以轻度盐渍化为主。轻度盐渍化多分布在 湖区红沙岗镇、红沙梁镇、西渠镇等镇;中度盐渍化分布在昌宁镇以及环河区沿风沙线一带。其评 价结果对民勤绿洲耕地资源的科学管理和可持续利用以及绿洲农业的发展具有重要意义。

  • 黄土丘陵沟壑区不同深度土壤水分对降雨的响应及其稳定性

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2021-04-14 合作期刊: 《干旱区地理》

    摘要: 通过采用点面结合的方法,分析黄土高原地区降雨影响下不同深度土壤水分的时空变化, 从土壤水分复杂的“变异性”中提取相对的“不变性”。结果表明:20cm以上土壤水分无明显规律, 难以表征不同植被类型或空间位置上的土壤水分差异;小于 30 mm 的降雨基本不会引起 40 cm 以 下土壤水分明显波动;100 cm 深处,各采样点的土壤水分能在一个稳定值上保持数月时间,在大于 46 mm 的强降雨之后出现阶梯式抬升,之后又保持稳定状态;越往土层深处,土壤水分时空稳定性 越明显,能较好的表征各植被类型或空间位置上的土壤水分差异。该研究从土壤水分的稳定性角 度进行分析,对黄土高原土壤水分的地面采样设计和时空预测具有实际应用价值。

  • Quantification of red soil macropores affected by slope erosion and sediment using computed tomography

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2021-03-17

    摘要:Purpose Soil structures are the main course of the formation and development of collapsing gullies, which are the most severe type of erosion in south China. However, few studies have focused on the relationship between soil macropores, soil erosion, and local topography. This study aimed to quantify and compare soil properties and macropore characteristics in the collapsing gully region, and explore their influences on the formation and development of the associated erosion. Materials and methods Soil core columns at different positions of a typical collapsing gully were excavated, and then scanned to analyze soil macropores. Moreover, soil properties and saturated hydraulic conductivity were investigated in the laboratory and in the field, respectively. Results and discussion The results indicated that the sand content increased from the ridge to the slope and the valley, while silt and clay contents decreased for the same catena. The mean weight diameter of aggregates was largest at the ridge and lowest at the valley. The infiltrate rates were highest at the valley and lowest at the slope. The valley had the greatest macroporosity (1.09±0.33%), and the highest number (5919±703), volumes (24.7±7.5 cm3) and surface (10.4±2.6 m2) of macropores, as well as the highest conectivity (42.3), while the slope had the smallest macroporosity (0.15±0.14%), and the smallest number (1189±747), volumes (3.4±3.2 cm3) and surface (1.7±1.4 m2) of macropores. The mean pore volume of macropores larger than 1 mm3 was largest at the ridge (16.8±7.4), and smallest at the slope (10.6±2.9). The number of macropores and their macroporosity mainly decreased with increasing depth, but were influenced by the soil macrofauna as well as the erosion and sediment processes. Macropores were mainly vertical, which is affected by the roots of plants and is conducive to the vertical infiltration of water. But, there wer many horizontal macropores at the valley because of the sediment process. The equivalent pore diameter of macropores was mainly smaller than 2 mm (accouting for more than 76.3%), and the macropores larger than 5 mm were less than 1%. Conclusions The macropore characteristics at different sites of the collapsing gullies affected the soil water infiltration and hydraulic conductivity, and further affected the processes of water erosion and mass ersion. The highest macroposities at the valley would result strong subsurface flow erosion and the loss of the base of collapsing wall. Macropores at the ridge would increase rain infiltration and promote soil collapsing. Few macropores and low infiltration abilities at the slope would strengthen the overland flow erosion. Thus, macropore characteristics had significant effects on both the formation and development of collapsing gullies.

  • 干旱区盐湖沿岸土壤呼吸特征及其影响因素

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2020-06-12 合作期刊: 《干旱区地理》

    摘要: 明确不同生态系统土壤碳排放规律及其影响因素对准确评估全球碳循环具有重要意义。为揭示干旱区典型盐湖沿岸土壤呼吸(Rs)、土壤呼吸温度敏感系数(Q10)变化特征及其影响因素,以新疆干旱区达坂城盐湖和巴里坤湖沿岸土壤为研究对象,在2015—2016年5~10月利用LI–8100土壤碳通量自动测量系统对盐湖沿岸土壤呼吸速率进行测定,分析了土壤呼吸季节性变化特征及其影响因子。结果表明,干旱区盐湖土壤呼吸变幅较大(0.07~11.59 μmol•m-2•s-1),平均值为2.45 μmol•m-2•s-1,7月土壤呼吸速率最高为4.69 μmol•m-2•s-1,10月最低(1.01 μmol•m-2•s-1);土壤CO2累积排放量为9.30 g•m-2•d-1,7月累积排放量最大为17.82 g•m-2•d-1。Q10呈“降低—增加—降低”趋势,6月最低(2.25)9月最高(3.52),平均值为2.79。干旱区盐湖沿岸土壤呼吸受土壤有机碳(SOC)、5 cm土壤温度(ST5)、土壤含水量(SM)和土壤盐分(Salt)的共同影响,单因素模型模拟可解释土壤呼吸速率变化的41.7%~75.7%(R2=0.417~0.757,P<0.05),多因子综合模型拟合结果最佳Rs=0.001×SOC+0.039 ×SM-0.534×Salt-0.116×ST5+5.06(R2=0.804,P=0.05),且均表明盐分是影响干旱区盐湖沿岸土壤呼吸速率的主要因子。因此,在考虑陆地生态系统碳收支和碳循环时不能忽略干旱区盐湖沿岸土壤碳过程,以及盐分对盐湖生态系统碳排放的影响。

  • Multi-scale spatial relationships between soil total nitrogen and influencing factors in a basin landscape based on multivariate empirical mode decomposition

    分类: 农、林、牧、渔 >> 土壤学 提交时间: 2019-06-20 合作期刊: 《干旱区科学》

    摘要: The relationships between soil total nitrogen (STN) and influencing factors are scale-dependent. The objective of this study was to identify the multi-scale spatial relationships of STN with selected environmental factors (elevation, slope and topographic wetness index), intrinsic soil factors (soil bulk density, sand content, silt content, and clay content) and combined environmental factors (including the first two principal components (PC1 and PC2) of the Vis-NIR soil spectra) along three sampling transects located at the upstream, midstream and downstream of Taiyuan Basin on the Chinese Loess Plateau. We separated the multivariate data series of STN and influencing factors at each transect into six intrinsic mode functions (IMFs) and one residue by multivariate empirical mode decomposition (MEMD). Meanwhile, we obtained the predicted equations of STN based on MEMD by stepwise multiple linear regression (SMLR). The results indicated that the dominant scales of explained variance in STN were at scale 995 m for transect 1, at scales 956 and 8852 m for transect 2, and at scales 972, 5716 and 12,317 m for transect 3. Multi-scale correlation coefficients between STN and influencing factors were less significant in transect 3 than in transects 1 and 2. The goodness of fit root mean square error (RMSE), normalized root mean square error (NRMSE), and coefficient of determination (R2) indicated that the prediction of STN at the sampling scale by summing all of the predicted IMFs and residue was more accurate than that by SMLR directly. Therefore, the multi-scale method of MEMD has a good potential in characterizing the multi-scale spatial relationships between STN and influencing factors at the basin landscape scale.