干旱区荒漠植被茎干液流影响因素研究

植物茎干液流能反映植被水分传输状况,被用于研究植被的生态需水量。因此,分析荒漠植被茎干液的流影响因素对新疆干旱区生态环境的改善有着重要意义。以玛纳斯河流域下游古尔班通古特沙漠南缘典型荒漠植被梭梭和柽柳为研究对象,进行野外数据监测,研究荒漠植被茎干液流速率的日变化特征,分析茎干胸周、各气象因子及地下水潜水埋深对茎干液流速率的影响。结果表明:1梭梭和柽柳茎干液流速率均呈明显的昼夜变化规律,白天液流速率远高于夜间。2液流速率的变化与空气相对湿度呈负相关,空气相对湿度越高液流速率低;气温、总辐射的变化与液流速率的变化呈正相关,气温或总辐射越大时茎干液流速率也越大。3相同试验点的同种植被,胸周较大,茎干液流速率越小,抗旱性强。4地下水埋深越浅,荒漠植被茎干液流速率越大,峰值越高,且峰值出现时间相对滞后。     

荒漠区柽柳液流特征及其与环境因子的关系研究

干旱荒漠区植被水分传输状况决定着区域生态需水量,进而影响生态安全。植物的茎干液流量表征其蒸腾耗水量,能够准确反映单株植物的蒸腾作用和水分利用状况。本文以古尔班通古特沙漠南缘典型荒漠植被柽柳为研究对象,采用茎热平衡法,对区域典型荒漠植被柽柳茎干液流及其与环境因子的关系进行了研究,结果表明：①柽柳茎干液流日变化曲线呈多峰格型,日平均液流率为0．00399g／s,最大值为O．0135g／s。茎干液流7：00～15：00一直保持较高值（0．003g／s以上）,21：00左右液流速率降到极低值;②柽柳风速变化和茎干液流速率存在相关性,微风可加快茎干液流,强风对茎干液流有抑制作用,而冠层温度与茎干液流速率呈正相关,冠层空气湿度与茎干液流呈负相关。     

黄土塬区苹果树干液流特征

应用热扩散式树干茎流计（TDP）于2012年7~10月对黄土塬区长武县苹果树干液流速率进行了连续测定,分析了气象因子、土壤含水率等多个环境要素对树干液流的影响。结果表明,在晴天和阴雨天苹果树干液流速率变化均呈明显的昼夜变化单峰曲线,晴天液流启动早,停止晚,液流速率大;阴雨天液流启动晚,停止早,液流速率小。苹果树干液流速率与太阳辐射、水气压差、大气温度和相对湿度呈显著正相关,与空气相对湿度呈显著负相关,晴天条件下液流速率与各气象因子的相关关系比阴雨天条件下显著,且均可用线性表达式来估算。在不同的土壤水分环境条件下,苹果树干液流速率变化差异很大。水分胁迫条件下,全天液流速率水平较低,反映其蒸腾水平低;而水分充足条件下,液流速率的变化过程为一宽峰曲线,维持较高液流速率的时间较长,全天蒸腾水平高。     

黄瓜气孔导度、水力导度的环境响应及其调控蒸腾效应

以营养生长期温室黄瓜为研究对象,通过四元二次正交旋转组合设计,分析稳态流条件下土壤相对含水率、空气温度、空气湿度和光合有效辐射对气孔导度、土壤植物系统总水力导度的影响及其调控蒸腾效应。结果表明,4个环境因子对气孔导度、总水力导度均有正效应,对其影响最大的环境因子分别是空气湿度、空气温度;土壤相对含水率与光合有效辐射、空气温度与空气湿度对气孔导度和总水力导度存在明显的交互作用;空气湿度对气孔导度、总水力导度的单因子效应为开口向上的抛物线函数,其他环境因子的单因子效应皆趋近于线性递增函数;各因子的边际效应分析表明,空气湿度是气孔导度的主要调控途径,除光合有效辐射外,其他因子均可有效调控总水力导度。采用通径分析方法研究了环境因子、气孔导度、总水力导度调控蒸腾效应,结果表明,空气温度、光合有效辐射和气孔导度均主要通过增强总水力导度对蒸腾作用产生间接正效应,其次是对蒸腾作用的直接正效应;土壤相对含水率主要通过增强总水力导度和气孔导度对蒸腾作用产生间接正效应;空气湿度的直接影响为负效应,但其主要影响途径为通过增强总水力导度和气孔导度对蒸腾作用的正效应;气孔导度与总水力导度响应环境因子变化并相互作用,协同调控蒸腾作用。     

基于~(18)O同位素的玛纳斯河流域典型荒漠植被水分利用来源研究

梭梭和柽柳是玛纳斯河流域下游典型荒漠植被,对干旱荒漠区具有水土保持和固沙造林的作用,分析其水分利用来源对保证植被正常生长、维持荒漠生态系统稳定具有重要意义。采用~(18)O稳定同位素技术,以玛纳斯河流域下游两年生梭梭、柽柳为研究对象,通过分析植被水、地下水和不同土层土壤水中的~(18)O值,得到两年生梭梭、柽柳旱季生长期的水分利用来源,研究结果表明:(1)年生长期内,地下水潜水埋深呈小幅增大,~(18)O值在5月到7月间逐渐增大,8月又逐渐减小;土壤含水率随着土层深度的增加而增大,土壤含水率月变化趋势为5月6月7月,土壤水中~(18)O值随着土层变浅而增大,100 cm以下逐渐稳定并趋于地下水;浅层土壤的~(18)O值随着月份的增加逐渐增大,较深土层土壤水的~(18)O值相对稳定。(2)两年生梭梭生长季节的主要水分利用来源为地下水和80~150 cm土层的土壤水,贡献率分别为56.8%±6.8%和26.3%±7.2%;两年生柽柳生长季节的主要水分利用来源为60~150 cm土层的土壤水和地下水,贡献率分别为54.6%±9.2%和36.8%±8.5%。     

空气温湿度对小麦光合作用的影响

对田间环境不同水分处理光合速率、蒸腾速率、叶片水分利用率和气孔导度的分析表明,增加土壤含水量有助于缓解空气高温低湿对小麦光合作用的胁迫。气温对蒸腾的促进作用随土壤含水量提高而得到加强,湿度降低对蒸腾的促进作用随土壤含水量提高而得到抑制。随着土壤含水量的增加,叶片水分利用率向高温低湿方向移动,低温低湿对气孔导度的抑制效应愈加明显。综合比较这几个指标,使叶片既能保持最高光合速率又能维持较高叶片水分利用率的土壤含水量为0.22 g/g。     

基于液流量的苹果树蒸腾量模拟

利用热脉冲茎流计监测西北旱区盛果期苹果树茎干液流变化规律,采用自动气象站测定气象因素的变化,在试验基础上分析了苹果树液流量的动态变化并分别采用基于冠层变化的季节蒸发蒸腾模型(Cj)、双作物系数模型(Kcb)和Priestley-Taylor模型对日均蒸腾量进行模拟。研究结果表明,日均茎干液流量呈先增加后降低的单峰曲线,基于冠层变化的季节蒸发蒸腾模型可以准确估算西北旱区盛果期果树的日均蒸腾量,模拟的日均蒸腾量可以减小液流量的时滞影响,提高长时间估算果树蒸腾量的精度。     

基于三温模型的盆栽柑橘蒸腾规律研究

为深入探究柑橘树冠层空间蒸腾特性及与茎干液流的对应关系,采用五点测温法,使用热成像仪拍摄柑橘树冠层五个方位的红外图像获取冠层温度及参考冠层温度,利用三温模型,将模型估算叶片蒸腾速率与实测茎流速率进行比较,并研究了柑橘树冠层不同方位的蒸腾变化规律.结果表明:柑橘树茎流速率与冠层叶片蒸腾速率日间变化曲线存在差异,决定系数(R2)为0.14,整体上,不同方位冠层温度与气温的日变化规律相近,柑橘树不同方位平均蒸腾速率大小分别为:东面>西面>北面>南面>顶面.上述结果表明:①柑橘树冠层蒸腾与茎干液流之间存在时滞效应,三温模型估算的叶片蒸腾速率不能实时反映树干液流的变化特征.②气温越高时,不同方位的冠层温度差异越显著.③柑橘树冠层空间蒸腾具有明显的空间差异性,揭示了柑橘树冠层蒸腾速率的空间变化规律.     

不同矿化度微咸水灌溉条件下柽柳的耗水规律试验研究

通过测坑试验,以准噶尔盆地南缘地区典型的荒漠植被柽柳为研究对象,对柽柳生长期内在不同矿化度微咸水灌溉水平下的耗水生长过程、形态变化、叶片水分生理特性等进行了较系统的试验研究,得出:①柽柳在土壤含水率为田间持水率的45%～50%时,矿化度为6g/L的微咸水灌溉条件下,柽柳仍能够维持生长,且该条件下柽柳的分枝数、枝长、冠幅等指标与较低矿化度条件下柽柳的相应指标相比,下降幅度在15%～30%之间;②分析柽柳的水分生理特性,通过叶片蒸腾速率、光合速率、气孔导度以及水分利用效率的日变化曲线,得出:柽柳在矿化度为3g/L时,其蒸腾速率、光合速率等是最高的,其后矿化度增大,光合作用减弱。柽柳属于低蒸腾、低光合沙生植物,叶片水分利用效率在上午的水分效率较高,而自中午之后一直维持在一个相对较低的水平。     

幼年期柽柳对不同矿化度微咸水灌溉响应的初步研究

干旱区玛纳斯河流域水资源严重短缺,防风固沙的人工植被常常不得不利用较高矿化度的地下水进行灌溉.研究采用3种矿化度(1、3、6 g/L)的微成水,对2年生柽柳进行补充灌溉.结果表明,较高矿化度微咸水对柽柳生理活动与生长速率具有明显的影响.多枝柽柳的光合速率、气孔导度和蒸腾速率的日变化曲线呈单峰型,日均值呈先增大后减小趋势...     

Overestimation of soybean crop transpiration by sap flow measurements under field conditions in Central Portugal

Direct measurements of the xylem sap flow by the stem heat balance technique can be a valuable aid for determining the irrigation demand of field crops. In the present study, soybean (Glycine max (L.) Merr.) sap flow was evaluated under well-watered and water-stressed conditions using Dynamax SGA10 sap flow gauges. Solar radiation was measured continuously throughout the growing season. Soil water content was measured before and after each irrigation. There was a close relationship between solar radiation and xylem sap flow. The water flux in the soybean stems responded realistically to changes in the soil water content. However, the absolute values of sap flow were highly questionable. Calculating crop transpiration from sap flow measurements, the results were up to 4 times as high as calculated transpiration from soil moisture data and simulated transpiration using the locally calibrated soybean crop growth model SOYGRO. A sensitivity analysis of the stem heat balance technique gave no indications of technique or input errors. The gauge design was possibly not appropriate for the outdoor installation on soybeans.     

微咸水灌溉梭梭田间耗水量与生长关系试验研究

以微成水资源的合理开发利用和受损荒漠植被覆盖率的提高为目标,通过测坑试验,探讨了1、3、6 g/L3种矿化度处理下梭梭的田间耗水量和生长规律,结果表明,生长期内3种矿化度处理下梭梭土壤0～140 cm耗水量分别为419.83、404.59、378.66 mm,不同处理耗水量的大小随矿化度增加而减少;梭梭株高和枝长的生长...     

温室滴灌条件下番茄植株茎流变化规律试验

为探明滴灌条件下温室番茄植株茎流速率变化规律及其影响因素,本文采用Dynamax公司开发的包裹式茎流计观测日光温室番茄植株的茎流变化,研究茎流速率的变化规律及茎流速率监测结果的标准化处理技术,探索植株茎流与气象因子的相互关系,分析水分胁迫对番茄植株茎流速率的影响。研究表明,采用单位叶面积上的茎流速率表征茎流变化规律可在一定程度上降低因探头安装位置不同对监测结果的影响;在充分供水条件下,影响番茄植株茎流速率的主要因子是太阳辐射和饱和水气压差,番茄植株的日茎流速率与太阳辐射呈线性关系,与饱和差呈对数关系（R2＞0.90,P＜0.01）;土壤水分状况会明显影响番茄植株茎流状况,茎流速率随水分胁迫加剧而骤减。研究结果证明番茄植株茎流速率经标准化处理后可以真实的反映植株蒸腾规律。     

旱地果园起垄覆膜集雨措施对树体水分利用的影响

针对甘肃陇东黄土高原旱地苹果园季节性干旱问题,以15年生长富2号苹果树为试材,研究果园起垄覆膜、小沟集雨技术措施对土壤水分、主干液流速率、叶片光合速率等的影响。结果表明,在萌芽前晴天,覆黑地膜能显著提高主干液流速率;在果树生长季节,覆黑地膜能降低株间蒸发量,较长时间保持土壤水分,提高水分利用效率和叶片光合能力,同时可以...     

Heat-pulse measurements of sap flow in olives for automating irrigation: tests,root flow and diagnostics of water stress

The compensation heat-pulse method for measuring sap flow is tested here in olive trees (Olea europaea L.). We describe a rigorous three-way examination of the robustness of the technique for this species, and examine the potential of the technique for an automatic control of the irrigation system. Two tests were carried out using heat-pulse gear inserted into the stem of 12-year-old ‘Manzanilla’ olive trees. One test used forced-flow through a stem section, and the other involved measured water uptake by an excised tree. The measured sap flow in these two tests was in agreement with calculations from heat-pulse velocities when using a standard ‘wound correction’ to account for the presence of the probes and the disruption to the sap flow. Thus, this technique for monitoring transpiration can, we feel, be used with confidence in olives.The third experiment was carried out in the field, where we analysed sap flow data from two 29-year-old olive trees — one tree was under regular drip irrigation and the other was from dry-farming conditions. We use measurements of sap flow in the trunk to examine the hydraulic functioning of the tree, and to explore some diagnostics of water stress. Our heat-pulse measurements in the irrigated olive tree exhibited a profile of sap flow that was weighted towards the outer xylem of the tree trunk while the water-stressed trees in the field showed a profile of sap flow weighted towards the centre of the trunk. The loss of hydraulic functioning in the outermost section of the vascular system, as a result of water stress, we consider to be due both to stomatal control and to embolisms in the xylem vessels.The fourth experiment was also carried out in the field, in which sap flow measurements were made at three locations in the trunk as well as in two roots of another 29-year-old olive tree. The soil explored by each root, on opposite sides of the trunk, was differentially wetted by separate irrigation of each side. Our data showed that the surface roots were able to absorb water immediately after wetting, despite a reasonably prolonged period of moderate drought. Root activity quickly shifted to the regions where the soil had been wetted. A root in dry soil exhibited no flow at night, whereas sap flows of about 0.02 l h⁻¹ were measured around midnight in the root drawing water from the wetter soil. Our observations suggest that the hydraulic behaviour of the trunk and surface roots might be used as a diagnostic of the onset, or severity, of water stress. Here there is not the imperative to replicate, for the prime goal is not transpiration estimation. Rather interpretation of the diurnal dynamics is used to infer the onset, or severity of water stress.The compensation heat-pulse seems a suitable technique for automatically controlling the irrigation system of olives, and probably other trees, based either on the estimation of the short-time dynamics of transpiration, or on changes in the hydraulic behaviour of the trees.     

不同水氮条件下桃树幼苗茎干液流变化规律研究

采用美国生产的DeTransfer 3.27茎流测定系统监测一年生的桃树幼苗树干液流变化.分析了不同水分、氮肥处理下桃树苗树干液流日变化和连日变化特征及茎流与蒸腾的变化关系.结果表明,桃树苗茎液流速率存在明显的日周期和连日变化规律.水分对桃树苗茎流的影响:在相同的氮素水平下茎液流速随土壤水分含量的增加依次增加,无氮处理下,茎液流流速在充分灌水条件下最大峰值为11 g/h左右,较低水条件下增加了15.8%,高氮处理下,茎液流流速最大峰值为23.5 g/h左右.氮肥对桃树苗茎流的影响:施氮肥明显地增加桃树苗茎液流速,在土壤水分供应充足条件下,茎液流流速分别为N1 11g/h、N2 16.5 g/h、N323.5 g/h;茎液流速和蒸腾速率动态曲线有着相似的变化趋势.     

热带桉树树干液流的时滞效应分析

【目的】探明热带桉树树干液流与环境因子间的时滞效应及其影响因素。【方法】运用Granier热扩散探针技术对海南省西北部儋州林场生长季(5—10月)桉树树干液流速率进行了实时监测,并同步监测了光合有效辐射(PAR)、大气温度(Ta)、相对湿度(Rh)和0～60cm土壤含水率(SWC),运用错位相关法分析了液流速率与PAR和饱和水气压亏损(VPD)之间的时滞长度。【结果】典型晴天下桉树液流速率日变化特征呈"双峰型"曲线,存在光合午休,液流速率抵达峰值时间较PAR和VPD提前约60 min;液流速率与环境因子(PAR、VPD)间均呈极显著正相关(P<0.001)。整个生长季桉树液流速率与环境因子间存在明显时滞,分别提前于PAR和VPD约30 min和50 min。SWC对桉树液流速率与环境因子间的时滞效应影响达显著性水平(P<0.05),当SWC较高(15.42%)时,液流速率对PAR和VPD的时滞分别为-60 min和-30 min,而SWC较低(10.45%)时分别为0和-60 min;桉树径级对液流速率时滞效应的影响未达到显著性水平(P>0.05)。【结论】热带桉树树...     

人工种植梭梭在荒漠化土地中植被恢复技术

土地荒漠化是当今世界面临的严重环境问题,在土地退化生态系统中植被恢复是恢复生态学的首要工作,同时植被恢复技术是荒漠化土地再利用的重要途径。在黑河中游临泽地区小泉子治沙站,通过在该地区设置机械沙障并人工种植耐旱植物梭梭,并对其根系周围土壤含水量、梭梭生长动态以及其对沙丘的防风固沙效果进行了研究。研究结果表明,人工梭梭在西北干旱半干旱的荒漠化地区具有较好的生长态势,在该地区典型沙丘上对不同坡度的沙丘进行研究,发现在机械沙障作用下,梭梭能够较好的生长,而且梭梭茎和根的生长量积累都是呈现出增长趋势;耐旱植物梭梭能够对典型沙丘起到较好的防风固沙效果,而且对其周围沙丘的流沙固定效果,随着梭梭根系的发达和茎冠的茂盛会逐渐增强。      

NaCl胁迫对梭梭种子萌发与幼苗生长的影响

试验以NaCl为胁迫因子,设置0、2、4、6、8、12、16、20、24、30、36g/L等11个盐质量浓度,对梭梭进行盐胁迫处理,通过分析相对发芽率、幼芽及幼根长、幼苗鲜质量和细胞膜透性等指标,研究NaCl胁迫对梭梭种子萌发及幼苗生长的影响。研究结果表明,NaCl胁迫质量浓度低于8g/L时,梭梭种子相对发芽率均在90...     

Evapotranspiration components determined by sap flow and microlysimetry techniques of a vineyard in northwest China: Dynamics and influential factors

Large areas of vineyards have been established in recent years in arid region of northwest China, despite limited water resources. Water to support these vineyards is mainly supplied by irrigation. Accurate estimation of vineyard evapotranspiration (ET) can provide a scientific basis for developing irrigation management. Transpiration and soil evaporation, as two main components of ET, were measured separately in a vineyard in this region by heat balance sap flow system and micro-lysimeters during the growing season of 2009. Diurnal and seasonal dynamics of sap flow and its environmental controls were analyzed. Daily sap flow rate (SR_l) increased linearly with solar radiation (R_s), but showed an exponential increase to its maximum curve as a function of vapor pressure deficit (VPD). Residuals of the two regressions both depended on volumetric soil water content to a depth of 1.0 m (VWC). VWC also significantly influenced SR_l. The relationship of them could be expressed by a piecewise regression with the turnover point of VWC = 0.188 cm³ cm⁻³, which was ∼60% of the field capacity. Conversely, soil evaporation (E_s) increased exponentially with VWC. Thus, we recommended keeping VWC in such vineyards slightly above ∼60% of the field capacity to maintain transpiration while reducing soil evaporation. Vineyard transpiration (T_s) was scaled from sap flow by using leaf area (A_l) as it explained 60% of the spatial variability of sap flow. Vine transpiration was 202.0 mm during the period from April 28 to October 5; while that of E_s was 181.0 mm. The sum of these two components was very close to ET estimated by the Bowen ratio energy balance method (386.9 mm), demonstrating the applicability of sap flow for measuring grape water use in this region.