六盘山半干旱区华北落叶松林土壤水分时空变化与影响因素
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摘要
分析森林土壤湿度时空变异规律,研究植被蒸腾、林地蒸散和气象因子对土壤湿度的影响,对干旱地区的植被恢复、林水协调管理和植被生态水文功能提升都有重要意义。在宁夏六盘山北侧半干旱的叠叠沟小流域,建立了华北落叶松人工林标准样地,利用气象站、热扩散探针、微型蒸渗仪、时域反射仪等设备,同步监测了2013年7—10月的气象条件、林木蒸腾、林地蒸散、土壤湿度的动态变化,并分层(0—20,20—40,40—60,60—80cm)探讨了土壤湿度的主要影响因子。结果表明:(1)受随机降雨事件影响,土壤湿度呈现相应的脉冲性变化;整体而言,表层(0—20cm)土壤湿度(32.69%)较低,以下各层较高(40.00%左右);土壤湿度的变异程度随土层加深和降雨增大而逐渐减弱。(2)影响土壤湿度的主要气象因子为温度、饱和水汽压差和气压;林木蒸腾和林地蒸散与整个研究期间主根系层(0—60cm)土壤湿度的相关性显著。(3)土壤湿度与各因子的相关系数随土层加深而变小,在主根系层明显,在以下土层(60—80cm)不明显。综上可知,森林土壤湿度同时受降水输入和蒸散输出影响,各土层湿度的时间变化规律相似;但表层土壤的湿度低、变幅大,土壤湿度对影响因子的响应敏感性和变幅随土层加深而逐步缩小。
Understanding the temporal and spatial variation of soil moisture of forest and studying the effects of vegetation transpiration,forest floor evapotranspiration and meteorological factors on soil moisture are important to vegetation restoration,integrated forest-water management and the improvement of the eco-hydrological functions of forest/vegetation in the arid regions.A stand plot of Larix principis-rupprechtii plantation was established in the semiarid Diediegou small watershed on the north side of Liupan Mountains,Ningxia.Meteorological conditions,forest transpiration,forest floor evapotranspiration and soil moisture during July to October in 2013 were simultaneously monitored by automatic meteorological station,thermal diffusion probes,micro-lysimeters and time domain reflectometry.The soil moisture was monitored in the layers of 0-20,20-40,40-60 and 60-80 cm,to explored the main factors affecting the soil moisture.The results showed that:(1)Affected by the random rainfall events,the soil moisture showed corresponding pulse variation.On the whole,the mean soil moisture(32.69%)of the surface layer(0-20cm)was relatively lower than that of the layers followed(about 40.00%).The variation range of soil moisture decreasedgradually with the increasing of soil depth and rainfall amount.(2)The main meteorological factors influencing soil moisture were temperature,saturation vapor pressure deficit and atmospheric pressure.The forest transpiration and forest floor evapotranspiration had a significant correlation with the soil moisture of the main root zone(0-60cm)during the whole study period.(3)The correlation coefficients between soil moisture and all the influencing factors decreased with the increasing of soil depth,which were significant in the main root zone,but no longer significant in the soil layers below(60-80cm).In summary,the forest soil moisture was affected by both the precipitation input and evapotranspiration output.The temporal variation of soil moisture in each soil layer was similar.However,the soil moisture of surface layer was low and with a larger variation range.The sensitivity and amplitude of soil moisture to the influencing factors decreased gradually with the increasing of soil depth.
Understanding the temporal and spatial variation of soil moisture of forest and studying the effects of vegetation transpiration,forest floor evapotranspiration and meteorological factors on soil moisture are important to vegetation restoration,integrated forest-water management and the improvement of the eco-hydrological functions of forest/vegetation in the arid regions.A stand plot of Larix principis-rupprechtii plantation was established in the semiarid Diediegou small watershed on the north side of Liupan Mountains,Ningxia.Meteorological conditions,forest transpiration,forest floor evapotranspiration and soil moisture during July to October in 2013 were simultaneously monitored by automatic meteorological station,thermal diffusion probes,micro-lysimeters and time domain reflectometry.The soil moisture was monitored in the layers of 0-20,20-40,40-60 and 60-80 cm,to explored the main factors affecting the soil moisture.The results showed that:(1)Affected by the random rainfall events,the soil moisture showed corresponding pulse variation.On the whole,the mean soil moisture(32.69%)of the surface layer(0-20cm)was relatively lower than that of the layers followed(about 40.00%).The variation range of soil moisture decreasedgradually with the increasing of soil depth and rainfall amount.(2)The main meteorological factors influencing soil moisture were temperature,saturation vapor pressure deficit and atmospheric pressure.The forest transpiration and forest floor evapotranspiration had a significant correlation with the soil moisture of the main root zone(0-60cm)during the whole study period.(3)The correlation coefficients between soil moisture and all the influencing factors decreased with the increasing of soil depth,which were significant in the main root zone,but no longer significant in the soil layers below(60-80cm).In summary,the forest soil moisture was affected by both the precipitation input and evapotranspiration output.The temporal variation of soil moisture in each soil layer was similar.However,the soil moisture of surface layer was low and with a larger variation range.The sensitivity and amplitude of soil moisture to the influencing factors decreased gradually with the increasing of soil depth.
引文
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[12]曹恭祥.宁夏六盘山华北落叶松人工林与华山松天然次生林蒸散特征对比研究[D].呼和浩特:内蒙古农业大学,2010.
[13]杨磊,张涵丹,陈利顶.黄土宽梁缓坡丘陵区次降雨对土壤水分补给效率与阈值研究[J].中国科学:地球科学,2018,48(4):457-466.
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[18]曾泽群,雷泽勇,魏晓婷.基于水分变化的沙地樟子松人工林土壤分层特征[J].干旱区资源与环境,2017,31(12):161-165.
[19]庄家尧,杨静,李垚,等.南京城郊栎林与草地不同层次土壤含水量的变化规律[J].林业科学,2012,48(12):101-108.
[2] Tyagi J V,Kumar R,Srivastava S L,et al.Effect of micro-environmental factors on natural regeneration of Sal(Shorearobusta)[J].Journal of Forestry Research,2011,22(4):543-550.
[3]侯贵荣,余新晓,刘自强,等.不同降雨强度下北京山区典型林地土壤水分时空变化特征[J].水土保持学报,2017,31(3):209-215.
[4]王正安,邸利,王彦辉,等.六盘山半干旱区华北落叶松林土壤水分对降雨的响应[J].干旱区资源与环境,2018,32(4):144-151.
[5]马婧怡,贾宁凤,程曼.黄土丘陵区不同土地利用方式下土壤水分变化特征[J].生态学报,2018,38(10):3471-3481.
[6]刘泽彬,王彦辉,徐丽宏,等.六盘山华北落叶松林坡面的土壤水分时间稳定性[J].水土保持学报,2017,31(1):153-159.
[7]张敬晓,汪星,汪有科,等.黄土丘陵区林地干化土壤降雨入渗及水分迁移规律[J].水土保持学报,2017,31(3):231-238.
[8]徐志尧,张钦弟,杨磊.半干旱黄土丘陵区土壤水分生长季动态分析[J].干旱区资源与环境,2018,32(3):145-151.
[9]冯永建,马长明,王彦辉,等.华北落叶松人工林蒸腾特征及其与土壤水势的关系[J].中国水土保持科学,2010,8(1):93-98.
[10]王艳兵,德永军,熊伟,等.华北落叶松夜间树干液流特征及生长季补水格局[J].生态学报,2013,33(5):1375-1385.
[11] Li Z H,Yu P T,Wang Y H,et al.A model coupling the effects of soil moisture and potentialevaporation on the tree transpiration of a semi-arid larch plantation[J].Ecohydrology,2017,10(1):e1764.
[12]曹恭祥.宁夏六盘山华北落叶松人工林与华山松天然次生林蒸散特征对比研究[D].呼和浩特:内蒙古农业大学,2010.
[13]杨磊,张涵丹,陈利顶.黄土宽梁缓坡丘陵区次降雨对土壤水分补给效率与阈值研究[J].中国科学:地球科学,2018,48(4):457-466.
[14]唐敏,赵西宁,高晓东,等.黄土丘陵区不同土地利用类型土壤水分变化特征[J].应用生态学报,2018,29(3):765-774.
[15]蔡进军,张源润,潘占兵,等.宁夏黄土丘陵区苜蓿土壤水分的时空变异特征[J].水土保持研究,2016,23(1):75-79.
[16]车宗玺,李进军,汪有奎,等.祁连山西段草地土壤温度、水分变化特征[J].生态学报,2018,38(1):105-111.
[17]岳宏昌,王玉,李缠云,等.黄土丘陵沟壑区土壤水分垂直分布研究[J].水土保持通报,2009,29(1):66-69.
[18]曾泽群,雷泽勇,魏晓婷.基于水分变化的沙地樟子松人工林土壤分层特征[J].干旱区资源与环境,2017,31(12):161-165.
[19]庄家尧,杨静,李垚,等.南京城郊栎林与草地不同层次土壤含水量的变化规律[J].林业科学,2012,48(12):101-108.