樟子松固沙林水量平衡特征

采用水量平衡的方法,于2010-2011年、2013-2014年5-10月用自制的小型蒸渗仪对章古台林分密度为404株·hm-2的32年生樟子松固沙林林内和林外土壤0~30 cm土层进行了蒸发散测定试验。结果表明,生长季期间林外0~30 cm土壤蒸发散达到284.8~428.4 mm,占同期降雨量的67.0%~101.2%,林内为226.28~369.6 mm,占同期林内降雨量的75.1%~105.2%,在特别干旱的年份才发生蒸发散高于降雨量的情况。     

杉木人工林蒸发散及能量消耗规律的研究

本文根据连续6年的观测数据,直接应用能量平衡方程,对杉木人工林的蒸发散及能量消耗进行了分析,结果表明,集水区杉木人工林每年因蒸发散消耗的能量为209434×10~8J/ha,占净辐射的74.7%;蒸散的水量为848.47mm,为年降雨量的79.6%;林冠和林地每年的蒸散耗能分别为186560×10~8J/ha和22891×10~5J/ha,蒸散量各为754.35mm和93.31mm。辐射能、水汽源、林木生理功能和乱流交换等因素,决定和制约着潜热能和蒸散量的时空变化。     

祁连山青海云杉林水量平衡的研究

在多年观测研究的基础上,利用水量平衡的方法和原理研究了祁连山森林主要类型青海云杉林的降水、截留、干流、蒸发散的分配过程及变化规律,结果表明:全年降水为433.5mm、透流量287.37mm、干流0.294mm、截留量145.83mm,分别占降水量的66.29%、0.068%、33.64%;径流量为239.98mm,占全年降水的55.36%;蒸发散量为156.54mm,占降水量的36.11%;土壤储水量增量23.63mm,枯落层持水量7.92mm,分别占降水的5.45%和1.83%。     

我国森林水文研究现状及发展趋势概述

在简要介绍我国森林水文研究历史的基础上，概述了我国森林与降水、径流、蒸发散、水循环和水质等方面的研究现状及主要成果，并对我国森林水文研究的未来民展方向进行了初步分析。     

滩地杨树人工林皆伐后蒸发散与产流变化

[目的]揭示杨树人工林皆伐对滩地蒸发散和产流的影响。[方法]基于涡度相关系统对长江滩地杨树人工林皆伐前后水汽通量连续3年(2010―2012年)的观测数据,通过对比皆伐前、后气候条件相似的2个时段(1整年)的蒸发散,揭示皆伐后研究区蒸发散的变化,并基于水量平衡反推研究区产流的变化。[结果]皆伐后土壤温度和水位上升,土壤表层含水量全年均值减小约0.03;研究区蒸发散皆伐前、后具有相似的日变化规律和季节动态特征,但皆伐后的全年蒸散量仅为皆伐前的66.3%;皆伐后研究区产流率(产流量/降雨量)从皆伐前的0.53上升至0.62;皆伐前、后7、8、12月的干旱指数(潜在蒸发散/降雨量)均大于1,其他时期均小于1。[结论]滩地杨树人工林皆伐后滩地蒸发散减少而产流率增加,加剧夏季干旱的可能性有所降低,但洪水爆发期间削减洪峰的能力也减弱。     

杉木人工林林分的湿度特征

本文根据在湖南省会同县杉木人工林定位研究站测定的数据,对林分内的各和湿度参数,包括降水量、蒸发散量、水汽压、绝对湿度、饱和水汽压、饱和水汽压差、比湿和相对湿度等因于的年变化、日变化及其垂直分布规律进行了分析。结果表明,优越的湿度环境适于杉木喜温暖、湿润的习性,有利于杉木的生长,是当地成为杉木中心产区的重要原因之一。     

第2代杉木近熟林水文学过程研究

根据2005年会同定位观测站第3小集水区实测数据,对第2代杉木近熟林进行了水量平衡和蒸发散研究.结果表明:2005年降水量为1077.5 mm,水分输出中,总径流量为191.90 mm,总蒸发散量899.49 mm,水分输出比水分输入多13.89 mm,这部分水量由原来贮存在土壤中的水分提供;与第1代杉木成熟林的水量平衡相比,林冠截留率降低了4.7%,总径流系数降低了2.1%,土壤蓄水多亏损0.1%左右,蒸发散系数由81.20%提高到83.48%.     

波文比在研究森林蒸发散中的作用及其处理

近年来,在利用热量平衡方程测算森林总体蒸发散的研究中,经常引用波文比的概念。所谓波文比,就是乱流热通量和蒸发耗热量之比。本文根据近地层大气水分热量交换过程的基本概念,并通过森林地区的实地观测,对波文比在研究森林蒸发散中的作用及其处理作若干必要的论述和讨论,这对测定森林总体蒸发散量是有价值的。利用能量守恒原理测定森林蒸发散的方法,中国科学院林业土壤研究所曾进行过专题研究,限于篇幅不在本文中赘述。     

塔里木河流域潜在蒸散发特征分析

以塔里木河流域为研究对象,分析了气候变化下流域潜在蒸散发(ET0)时空特征.基于塔里木河流域及周边40个气象站点1970～2019年逐日气象资料,选取Penman-Monteith公式计算ET0,运用趋势检验法和Pearson相关分析对流域ET0时空变化及与气象因子关系进行了分析.结果显示:塔里木河流域多年ET0总体上...     

波文比能量平衡法的应用及其误差分析

下垫面蒸发散的测定,始终是森林气象学家和微气象学家难于解决的问题。尽管现在已经有了多种估算模式和测定方法,但大多数方法都不能很好地解决精度和实用性这一矛盾。在现有的种种测算方法中,波文比能量平衡法(BREB)是一种精度高、实用性较强的方法。     

苹果-小麦复合系统小麦潜在蒸散模拟模型的研究

根据FAO(1991)推荐的参考作物需水量(ET0)计算模式(FAO Penman Monteith),并通过作物系数、农林复合系统作物光胁迫系数及风速减弱系数的综合订正,建立太行山低山丘陵区苹果 小麦复合系统小麦潜在蒸散量计算模型,并利用Li 1600稳态气孔仪实测得到小麦蒸腾量,经转换后得出蒸散量对模型进行验证,旨在探索农林复合系统中作物蒸散的计算方法,为进一步开展水分生态特征的研究提供可行性途径。结果表明:小麦拔节 乳熟期间,模拟值与测算值吻合效果较好,二者线性相关系数可达0 9630(n=51),相对误差平均值为9 68%,t=0 075<相似文献   

植被蒸散研究方法的进展与展望

对蒸散研究方法的发展阶段及传统蒸散研究方法(水文学方法、微气象学方法、植物生理方法、模型分析方法、经验方法)的优缺点进行简要评述.同时详细介绍闪烁通量技术、遥感技术应用于蒸散研究的基本原理及优点和存在的问题.进一步阐述新技术方法在蒸散研究中的应用,并分析预测蒸散研究的未来发展趋势.     

鼎湖山亚热带季风常绿阔叶林蒸散研究

运用Penman蒸散力公式和理论上导上导出的计算森林生态系统蒸散公式，对亚热睦带性群落鼎湖山季风常绿阔叶林的蒸散力和蒸散逐日进行计算，其结果表明：鼎湖山季风常绿阔叶林蒸散力年平均为９８７．５mm占同期降雨量的４７％，蒸散力最大的月分是７月，最小的月份是２月，这样基本上与近地面层的气温度变化规律相一致，而与同期的降雨量有所延迟。林外自由水面蒸发年平均为１１９４．５mm干季林内蒸散力明显小于林外自由水面的蒸发，而湿季两者又十分接近，因此，两者相比可用来作为该地区划分干湿季的一个参指标，理论公式法所计算出该系统的蒸散年平均为９５１．９mm,与蒸散力相当，占同期降雨量的４５．３％。鼎湖山季风常绿阔叶林总径流量年平均为１１０３．８mm，径流系数为０．５２，研究期间系统贮水量的变经年平均为３８．９mm.水量平均法所得的蒸散年平均为９６０．１mm与公式法计算所得的蒸散非常接近，３年的系统误差不到１５，因此，初步得出此公式是计算森林生态系统蒸散的一种值得推广的方法。     

祁连山(北坡)林区气候特征分析

分析研究了祁连山森林生态站西水试验区地面气象站气象要素的多年观测资料，揭示了祁连山林区平均气温、降水量、蒸发量和日照时数等主要气象因子年内、年际变化规律及特征，为按照气候变化规律进行农业生产及生态环境建设提供了可靠依据。     

Determining transpiration coefficients of Sahelian vegetation barriers

Vegetation barriers along contour lines are an appropriate measure for runoff management. An essential element of their design is minimisation of competition for water between the agricultural crop and the vegetation barrier. This requires the evapotranspiration of the vegetation barrier to be known. In 1998 FAO (the Food and Agricultural Organisation of the United Nations) presented a method to estimate the evapotranspiration of natural vegetation. The method includes a dual crop coefficient approach, distinguishing soil evaporation and canopy transpiration. The transpiration coefficient can be obtained from either the LAI (leaf area index) or the fractional ground cover. This paper reports the results of a study conducted in Burkina Faso in 1998. Transpiration coefficients of three vegetation barriers were obtained by directly measuring transpiration and soil evaporation during the mid-season growing stage. Measured values were compared with those obtained from the FAO estimation method, using both the LAI and the ground cover approach. In most cases the FAO approach overestimated the transpiration coefficient. To overcome overestimation FAO proposes a reduction factor based on the stomatal resistance of vegetation with high stomatal control. This factor is difficult to obtain, however, and complicates the relatively simple method of estimation. Even if this reduction factor is taken into account, an overestimation of transpiration coefficients when using the LAI approach should still be acknowledged.This revised version was published online in November 2005 with corrections to the Cover Date.     

The soil water regime in a young radiata pine plantation in southeastern Australia

The soil water regime from planting to age seven years beneath plantations of Pinus radiata D. Don on first and second rotation sites has been studied by measuring changes in water-table depth and soil water content. Both plantations received intensive management, which produced very high growth rates.Magnitude and, to a lesser extent duration, of groundwater peaks decreased from planting, and by the time plantations were 5 years old the winter rise was negligible. Within 2 years of planting, soil water in the uppermost 1 m was largely depleted during summer periods, and by the fifth summer available water to 3 m depth was exhausted. A model relating change in water content to time from planting, and cumulative rainfall explained over 95% of the variation in water content. Daily changes in water content, which varied from 1.7 to 5.3 mm from winter to summer, related strongly to rainfall but weakly to pan evaporation. No relationship between evapotranspiration and soil water content was found.A rapid early depletion of soil water through vigorous plantation growth resulting from intensive silviculture was observed. This could cause problems in sustaining rapid growth rates beyond canopy closure, where access to groundwater is not possible. A judicious balance of fertilization and crop density, related to site characteristics, would be necessary to achieve optimum productivity.     

Regional variation in rate of mass loss of Pinus sylvestris needle litter in Swedish pine forests as influenced by climate and litter quality

The climatic influence on plant litter decomposition has been successfully correlated on a regional level by using estimated actual evapotranspiration (AET) and annual mass loss. This approach was applied to decomposition studies carried out in a transect along Sweden with litter incubated in four different forest types. A unified needle litter was used and among 14 Scots pine sites about 80% of the mass‐loss rate could be explained. A simple model was made on the influence of both climate and nutrient concentrations (nitrogen and phosphorus) on mass‐loss rate. About 90% of the first‐year mass loss could be explained by this approach. As early decomposition stages were studied (<40%) no influence of lignin was observed.     

Apparent controls of mass loss rate of leaf litter on a regional scale

First year litter mass loss was well correlated with actual evapotranspiration (AET) on a global scale. Decomposition values (in the range 0–90% accumulated mass loss) from the literature were compared with AET and to the litters’ nitrogen and lignin concentrations. As much as 65% of the decomposition rate could be explained by AET (n=92). Although both nitrogen and lignin separately gave significant relationships they did not appreciably change the coefficient of determination when added to the AET relationship. Dividing the data into boreal and tropical sets led to a change in the degree of relationship with AET and the chemical components. Higher coefficients of determination were obtained in the tropical systems (about 78 % of the decomposition could be explained by AET and lignin concentration) whereas in the boreal systems AET and nitrogen concentration could explain about 16%. Data on 92 observations of mass‐loss conducted at 25 sites ranging in AET from 285 to 1105 mm were combined to develop new continental scale models of mass loss and to test for the significance of litter quality variables at such scales. Highest monthly precipitation (HPRE), annual precipitation range (PRANGE) and annual AET could each account for about 65% of the variability in rates of mass loss. The best two‐variable model was provided by the combination of AET and PRANGE, explaining about 71% of the mass loss.