帽儿山天然次生林融雪径流可溶性有机碳时间动态及垂直分布

融雪期是北方地区可溶性有机碳(DOC)通过融雪径流从陆地生态系统向河流输出的关键时期,因此观测融雪径流DOC动态对分析流域碳流失至关重要。在帽儿山生态站选取东北东部典型天然次生林建立25 m×25 m的水量平衡场,测定分析2014年融雪期不同土层(5、35、65和95 cm)融雪径流DOC含量和通量的时间动态和垂直分布规律。结果表明: 1) 该融雪期土壤水量输入和输出分别为74.2和15.6 mm,径流率高达21%;融雪期DOC输出量与冬季大气输入量基本持平,分别为0.25和0.22 g/m2。2)高峰期DOC含量与其瞬时流量的相关性随土层而变。5和35 cm土层DOC含量与瞬时流量之间均无显著关系(P0.05);65 cm土层则表现出弱负对数关系(R2=0.29,P0.05),而95 cm土层呈现显著线性正相关(R2=0.43,P0.05)。不同土层DOC瞬时通量与瞬时流量之间均极显著正相关(R20.9,P0.001),且产流量越大的土层,其正相关回归方程的斜率也越大,表明水文驱动土壤DOC流失。3)融雪径流产流量和输出DOC通量大小均表现出35 cm5 cm95 cm65 cm土层趋势,其中5和35 cm土层是DOC的主要输出层,占总输出量的70%,而在融雪高峰期可高达90%。由于土壤的滞留作用,DOC含量波动范围随土层加深而向低浓度收敛。      

简单屋顶绿化的滞蓄特性

设计了模拟降雨与数据采集系统,研究了短时强降雨下简单屋顶绿化基质(配比：陶粒57.0%、草炭41.5%、保水剂1.5%)的降雨产流过程,基于37次模拟降雨实验,归纳了降雨产流的一般过程、规律和特性,分析了降雨强度、基质厚度和基质初始含水率对简单屋顶绿化滞流蓄水特性的影响。结果表明：基质厚度和基质初始含水率对简单屋顶绿化的蓄水特性有显著影响,基质初始含水率越低、基质厚度越厚时蓄水特性越佳。建立了产流时间数学模型,简单屋顶绿化降雨产流时间与降雨强度呈负相关,同时也受初始含水量和基质厚度影响。随着干湿循环次数增加,基质的厚度总体呈现下降趋势,储水性能逐渐下降,延迟产流时间逐渐缩短。     

长江上游低山丘陵区小流域森林植被变化对径流影响分析

森林植被的变化可以调节森林水文过程。本文以广元市碗厂沟的5个小流域为研究对象,根据实测水位资料,分析了在植被恢复过程中流域径流的变化情况。结果表明:随着森林植被的不断恢复,(1)流域降水转化为径流的数量(即径流系数)降低;(2)在相同的雨量级与相似的雨强情况洪峰得到削弱,洪峰时间延长;(3)在相似的降雨历时的条件下洪水过程线历时增长。     

广西不同植被类型地表径流的研究

1982—1989年,采用定位对比对不同植被类型的地表径流量及动态进行了观测研究。结果表明:1.不同植被类型的地表径流差异很大,草坡>针叶林>阔叶林或针阔混交林;区内各植被类型的径流系数较小,平均为0.78％,但各类型间差异很大,可达57倍强。2.地表径流的季节动态,主要受降水的季节分配规律制约;而不同植被类型的地表径流量主要受植被的树冠群体或植物群体、枯枝落叶层和土壤层的综合效能所决定。这种综合效能呈现阔叶混交林或针阔混交林大于针叶林、针叶林大于草坡地的规律。文中还建立了不同植被类型地表径流深与林外降雨量的回归模型。     

祁连山主要植被下土壤对降雨分配的研究

以祁连山主要植被类型下的土壤为研究对象，对其物理性质、渗透率、渗流速度及其地表径流进行研究，结果表明：土壤的物理性质决定着土壤对降雨的分配情况，有林地将降雨全部分配成入渗水，而牧坡草地根据降雨强度和持续时间不同将降雨按不同的比例分配成入渗水和地表径流水2部分，不同植被的土壤蓄水量也各不相同。林地土壤100cm土层蓄水量为320．2～509．7mm，比牧坡草地高5．4％～60．47％，灌丛云杉和高山灌丛土壤蓄水量最高；轻度放牧的草地土壤蓄水量比强度放牧的高33．48％。     

黄土高原沟壑区油松侧柏与沙棘混交的人工林的水文影响

采用国家标准森林分析方法进行了沙棘与油松、侧柏人工混交林的水文影响研究,结果表明:混交林内年均降水量较林外减少了20.1%;林内月降水量的季节变化以夏、秋、春、冬依次递减;年均气温比纯林内低0.1℃,相对湿度高4.5%;乔木层年均截留量较纯林提高了56.6%,灌木层提高了395.7%;年均地表径流量105.8 L,径流摸数为10.58 m3·km-2·a-1,纯林分别为1 349.05 L和134.9 m3·km-2·a-1,土壤侵蚀模数为0.65 t·hm-2·a-1,纯林为9.2 t·hm-2·a-1;枯枝落叶层现存量增加了200%;平均容水量为自身质量的3.1倍;土壤密度和土粒密度分别减少了6.3%和17.7%,含水量、孔隙度和通气度分别提高了6.1 %、13.9%、20.3%.不同土层土壤密度和土粒密度由上到下逐渐增大,孔隙度和通气度表层较高,向下逐渐减少;底层、中层和表层土壤非毛管孔隙度分别提高了113.3%、38.6%和32.6%;最大持水量、最小持水量、毛管持水量分别较纯林平均高11.0%、9.8%、10.5%,较荒地高36.0%、16.0%、25.6%;储水量和0～40 cm储水量分别较纯林和荒地提高了12.4%、22.7%,排水能力也较强.     

北京九龙山林地对降雨的调蓄功能*

对北京九龙山油松林、侧柏林、阴坡灌木林、阳坡灌木林的林冠层、枯落物层及土壤层对降雨的调蓄功能进行了研究，结果表明：四种不同林地的林冠截持率为２２％～３２％，大暴雨下的截持率为７％～１０％；枯落物层的有效调蓄为０．４６～２．４２ｍｍ；５０ｃｍ土层的快速、慢速和变化调蓄量分别为３５～４８ｍｍ；５４～４８ｍｍ，２８～５２ｍｍ；四种林地调蓄功能的顺序从大到小为油松林、阴坡灌木林、阳坡灌木林、侧柏林。     

广州南香山水库森林水文季节变化研究

为了提高森林水文研究过程中数据采集的精确性,应用现代测绘技术,包括水准测量、全站仪三维坐标测量、GNSS 卫星测量及测深仪的水深测量等,研究了广州南香山水库的库容变化规律,反演水库上游森林径流。研究结果表明：南香山一年内的降雨量分布出现类似双波浪形的变化,波峰出现在5月份和8月份,波谷出现在1月和10月;降雨量与库容增量存在线性关系,相关系数为0.9152;地表径流的大小主要与植被类型,土壤水分的饱和度及地形有密切关系。相比传统的测量方法,现代测绘技术更精确地反映了广州南香山地区森林水文的变化规律。     

人工降雨条件下不同坡度红壤坡面迳流泥沙变化特征研究

在人工模拟降雨强度为1.44 mm/min的条件下,研究了不同坡度(β)红壤近似裸地坡面迳流、泥沙的变化特征,研究结果表明:①地表迳流量随坡度的增大而迅速增加。②当β≤23°时,土壤侵蚀量随坡度的增大而迅速增加;当25°≤β≤40°时,土壤侵蚀量随坡度变化较小。③坡面土壤侵蚀的临界坡度则介于23°~25°之间。④坡度与侵蚀量关系可用函数表示为:S=199.1×L1.65×tan1.4β(0°≤β≤23°)。     

Effect of forest vegetation on runoff and sediment production in sloping lands of Loess area

According to fixed-position data for 1985–2003 from nine runoff plots of Caijiachuan watershed which lies in Jixian County of Shanxi Province in Loess area, this paper studied the relationship between vegetation and runoff and sediment production in sloping lands in detail, which helps to provide scientific basis for vegetation re-construction and studies on environmental transformation of water and sediment in watersheds of Loess area. Although, many study results testify that forest vegetation has an important function in soil and water conservation and cutting runoff, the effect of vegetation on runoff and sediment transmission is complicated, and this needs to be studied in depth. The results of the paper showed the following. Firstly, the natural secondary forest performs better function of soil and water conservation than artificial Robinia pseudoacacia forest, and runoff and sediment produced in the former in individual rainfall were 65%–82% and 23%–92% of those produced in the latter. At the same time, better correlative relationship between runoff and sediment production and rainfall and rainfall intensity were testified by multiple regression, but the correlation decreased gradually with the increase of canopy density of forest. Secondly, the difference of runoff and sediment production in several land use types was very distinct, and the amount of runoff and sediment produced from Ostryopsis davidiana forest and natural secondary forest were the least, and runoff and sediment produced from in artificial Robinia pseudoacacia forest and Pinus tabulaeformis forest were 5-fold as much as those from O. davidiana forest. Besides, runoff and sediment produced in mixed planting of apple trees and crops were 16.14-fold and 2.96-fold than those of O. davidiana forest, respectively, but the amount decreased obviously after high-standard soil preparation in the case of the former. Thirdly, based on gray cognate analyses of factors affecting runoff and sediment production in sloping land, the factors of stand canopy density and herb and litter biomass were the most significant ones, whose gray incidence degree exceeded 0.6. Therefore, mixed forest with multi-layer stand structure and shrub forest should be developed in vegetation re-construction of Loess area, which will help to increase coverage and litter thickness in order to cut down the runoff and sediment dramatically in sloping land. __________ Translated from Chinese Journal of Applied Ecology, 2005, 16(9): 1,613–1,617 [译自: 应用生态学报, 2005, 16(9): 1,613–1,617]