毛乌素沙地沙地柏（Sabina vulgaris）的水发生态初步研究

对毛乌素沙地沙地柏群落的水分状况作了初步研究,在典型的沙地柏群群落中选取位于丘顶（水分条件较差）和丘间低地（水分条件较好）的两个样地作为研究对象,观测了植物叶子的蒸腾速率,气孔阻力及水势等生理生态指标,并结合群落特征和土壤水分状况,探讨了水分与亏缺对沙地柏的影响。研究结果表明：１）虽然沙地柏具有比多数沙生灌木国小的蒸腾速率和更强的抗旱性,但是在不能利用地下水的情况下,其过大的密度可经起大量蒸腾耗水     

依据野外实测的蒸腾速率对几种沙地灌木水分平衡的初步研究（英文）

 本文旨在将毛乌素沙地植被建设的水分平衡与半固定沙丘持续发展原则应用于治沙造林的实践中。毛乌素沙地是一个灌木“王国”,然而沙地灌丛植被的发育常常受到水分亏缺的严重制约。为此,根据水分平衡的原则与方法确立适宜的植物种植密度,对沙地植被的经营管理具有重要的指导意义。在水分平衡研究中,蒸散是最难估计的一项。本文提供了一种根据叶面积指数的季节变化与蒸腾速率的观测资料计算蒸腾耗水量的方法,并根据沙地水分平衡的要求估算丁几种优势灌木的适宜种植密度。结果表明,毛乌素沙地灌丛生态系统的蒸发散主要来自植物蒸腾作用;在所研究的植物当中,除沙地柏(Sabina vulgaris)可以形成很大的密度外(因其强的蒸腾控制能力),其它灌木的适宜种植密度应控制在使沙丘处于半固定状态的水平上。     

不同苗龄沙地柏抗旱生理特性比较研究

以相同来源的1、3、5年生沙地柏幼苗为材料,采用室内生长池人工控水模拟不同干旱胁迫条件,对10个抗旱相关生理指标进行考察,探讨沙地柏苗龄对其抗旱特性影响。结果表明:（1）沙地柏叶片的保水力、细胞膜透性、RuBP羧化酶活性在胁迫前不同苗龄间差异显著,而叶片相对水分亏缺、气孔导度等指标不同龄苗间差异不显著。（2）在干旱胁迫条件下,随土壤含水量的降低,不同苗龄沙地柏的叶片水分亏缺、气孔导度差异一直不显著,而其净光合速率、蒸腾速率、水分利用率、胞间CO₂浓度在6.78%土壤水分含量时出现显著差异;当土壤水分含量降低到4.52%时,不同苗龄的叶片光量子效率也出现显著差异。（3）各苗龄组随着干旱胁迫的加剧,5年生沙地柏净光合速率、RuBP羧化酶活性、光量子效率显著低于1年生沙地柏,而其胞间CO₂浓度显著高于1、3年生沙地柏,并且其气孔导度、蒸腾速率随土壤水分含量降低而下降的幅度最大,水分利用率增加幅度比1、3年生的更多。研究表明,不同苗龄沙地柏幼苗抗旱性指标对干旱胁迫的响应程度存在差异,抗旱指标对苗龄的稳定性不同;干旱胁迫条件下低苗龄沙地柏比高苗龄的生长势更强,更有生命活力,但高苗龄沙地柏对水分胁迫的适应能力强于低苗龄;另外,在进行抗旱鉴定时,试验苗木年龄最好一致,抗旱鉴定指标选取也需考虑其对材料年龄的敏感性及稳定性。     

羊草群落水分状况的初步研究

本文采用笔者自行设计和组装的人工气候箱装置,对天然羊草(Aneurolepidium chinense)群落的水分状况进行了研究,结果表明,在生长季各时期的晴天条件下,羊草群落蒸腾、蒸散速率的日进程曲线均为双峰型。群落的蒸腾、蒸散速率与太阳总辐射强度和气温呈正相关,与空气相对湿度呈负相关。群落的无效水分散失比率与蒸腾速率呈负相关。群落中植物的蒸腾强度,以开花期最高,为1.156g／cm2(叶面积)／d;整个群落的蒸腾速率在种子蜡熟期达到最高值,为4861.07g／m2(地面)／d。群落的蒸散速率在6月份最高,达6454.36 g／m2／d。群落月蒸散、蒸腾耗水量的最大值分别出现在6月份和8月份,各为125.9mm和83.9mm。在生长季中,群落的总耗水量与总降水量基本相等,但二者的季节消长不同步。在植物生长发育早期的6月份,水分亏缺严重,使群落对后期充沛的降水不能有效利用,群落生产力低下。     

沙地柏叶型变化的生态意义

沙地柏（Sabina vulgaris）的叶包括刺叶和鳞叶两种类型。本文探讨沙地柏刺叶与鳞叶的结构和功能差异的生态意义。结果表明：（1）刺叶的角质层厚度、表皮细胞大小、叶肉细胞表面积和维管束大小都显著小于鳞叶;（2）刺叶的组织密度和失水系数都明显大于鳞叶;（3）刺叶的净光合速度、蒸腾速率和胞间CO2／大气CO2比都显著大于鳞叶,而前者的水分利用效率显著低于后者。这些结果指示：沙地柏刺叶的光合产物积累和水分丧失量大于鳞叶,但前者的抗旱保水性、耐辐射能力和水分利用效率都低于后者。刺叶和鳞叶的结构和功能差异表明：沙地柏叶型变化在一定程度上具有适应意义。     

内蒙古半干旱草原区沙地植物群落光合特征的动态研究

沙蒿(Artemisia intramongolica)群落是半干旱草原地区沙地的重要植被类型,分别在植物的生长前期、中期、盛期和后期采用便携式光合测定仪和大型同化分析仪测定了沙蒿叶片和沙蒿群落的光合动态。单叶和群落的光合速率日进程类型随气候的不同而异,瞬时光合速率主要决定于光合有效辐射强度(PAR)。土壤干旱大大降低了单叶和群落的光合能力,晴天土壤湿润时气温和空气湿度控制着叶片的光合速率,午间大气湿度降低是光合午休的主要外因。叶片的蒸腾速率与气温呈显著线性相关,植物的光能和水分利用效率也主要取决于PAR和气温,随着PAR和气温的升高利用效率下降。沙蒿叶片光能利用效率在后期也能保持较高水平。沙蒿对土壤干旱和高温具有一定的适应性,在土壤湿润时能迅速提高光合速率,形成较大的生物量。但是沙蒿的蒸腾速率高,水分利用效率低。研究认为,沙蒿通过对土壤干旱和高温的忍耐机制而保持长时间较高的光能利用效率,并在土壤湿润时迅速提高光合能力和积累干物质来适应半干旱的沙地环境,而且依靠高蒸腾速率和强的水分吸收能力来竞争性抑制其他植物的生长。     

植物剪枝蒸腾速率变化规律的初步研究

通过对毛乌素沙地几种主要植物的枝条在剪断前后的蒸腾速率的研究 ,发现这些植物枝条的蒸腾速率在剪离母株后一般会发生较大的变化 ,说明用快速称重法测定得到的剪断枝条的蒸腾速率与剪断前植物的实际蒸腾速率也存在较大的偏差。由于这类变化与植物的生物学特性、生长环境的水分条件、测定时叶片的水分状况、剪断的部位和测定的时间等多种因素都有密切关系 ,定量地预测某个植物剪断枝条的蒸腾速率的变化一般也比较困难。用快速称重法测定植物的蒸腾速率需要有同步的校正措施 ,否则结果不可靠。气孔计在测定植物枝条剪断前后蒸腾速率的相对变化率时比较准确。因而 ,用快速称重法测定植物的蒸腾速率 ,用气孔计来校正其偏差 ,这种二合一的方法是测定植物蒸腾速率比较准确而理想的方法     

沙地柏雌株与雄株的叶结构和功能比较

沙地柏 (ＳａｂｉｎａｖｕｌｇａｒｉｓＡｎｔ )常雌雄异株 ,稀雌雄同株 (中国植物志编委会 ,1978)。作为毛乌素沙地的一种天然常绿灌木 ,沙地柏以其对半干旱、养分贫瘠沙地环境的较强适应性吸引了许多研究者 ,研究内容涉及叶结构、气孔分布和导度、光合速率、蒸腾速率、水势、群落特征等。然而对沙地柏雌雄植株的叶结构和功能差异仍了解很少。性别分化有助于植株更好地发挥各种功能 ,与性别分化相伴随的便是植株结构和功能发生特化。综合分析结构与功能的关系有助于阐明格局、解释过程 (Ｒｉｃｋｌｅｆｓ等 ,1996)。雌雄植株的结构和功能差…     

水分共享在毛乌素沙地4种灌木根系中的存在状况

为揭示水分共享在毛乌素沙化草地4种沙生灌木根系中的存在状况,选择酸性品红为示踪剂开展野外实验。结果表明,只有沙地柏（Sabina vulgaris)和油蒿（Artemisia ordosica）根系具有共享水分的潜力,而沙柳Salix psammophaila)和杨柴（Hedysarum mongolicum)根系不具有这种潜力。基于酸性品红在细根中的存在状况以及沙子与酸性品红发生中和反应,被步认为沙地柏和油蒿根系可能具有提水作用潜力。     

毛乌素沙地三种灌木群落的水分利用过程

沙地柏、黑沙蒿和沙柳是毛乌素沙地的3种优势灌木群落。利用稳定同位素技术研究了3种灌木及伴生植物杨柴主要利用的水分来源,结合叶片稳定碳同位素值与土壤水分监测,从而确定灌木群落如何利用水分。结果表明:7月和9月3种群落内浅层土壤水的稳定氧同位素值接近雨水。沙地柏5月主要利用25 cm浅层土壤水,而7月和9月主要利用10—25 cm浅层和100—200 cm深层土壤水。黑沙蒿和伴生的杨柴5月主要利用10 cm浅层土壤水,7月同时利用10 cm浅层土壤水和150 cm深层土壤水,9月则利用10—150 cm土壤水。沙柳5月主要利用10—25 cm浅层土壤水,伴生的杨柴主要利用50—200 cm土壤水;7月它们同时利用10—25 cm浅层土壤水和100—200 cm深层土壤水;9月都主要利用25—200 cm土壤水。4种植物的叶片稳定碳同位素值存在季节动态和种间差异。常绿灌木沙地柏的叶片碳同位素值比较稳定,而且高于其他3种落叶灌木和半灌木。5月浅层土壤含水量较低时3种落叶植物的叶片碳同位素值较高。因此,降雨补充的浅层土壤水是3种灌木群落利用的主要水分来源。3种灌木及其伴生植物根据不同深度土壤水的可利用性,在不同季节利用不同深度的土壤水。杨柴与黑沙蒿或沙柳均存在水分竞争。沙地柏的叶片稳定碳同位素值较高,干旱时具有竞争优势。干旱时落叶灌木和半灌木能够提高叶片稳定碳同位素值来适应环境。     

干旱条件下臭柏的生理生态对策

为了探讨臭柏（Sabina vulgaris）的耐旱生理生态适应对策,进行了长期的野外调查和室内模拟实验。野外调查是在毛乌素沙地的天然臭柏分布区内,设置固定样方,调查分析;室内实验是将臭柏插穗带往日本冈山大学,移植于砾耕栽培装置中,设置对照区,弱干旱胁迫区,强干旱胁迫区（培养液渗透势分别为0 MPa,-0．1MPa和-0．3MPa）3种处理进行长期的干旱胁迫室内模拟实验,研究各处理区臭柏的生理生态学特性,结果表明,在干旱胁迫条件下,臭柏表现出积极的生理生态适应对策：（1）在生长方面,通过降低密度、自然稀疏及下部枝叶干枯的方式,以牺牲局部,确保个体生存的生态策略,有效地利用资源,维持种群的生存。（2）在气体交换方面,气孔关闭,气体交换速率减缓,光合速率和蒸腾速率都下降,但是,与光合速率相比,由于蒸腾速率受到更强烈的抑制,水分利用率提高。（3）在吸水保水方面,通过渗透调节能力的增强,细胞壁弹性的降低,增强忍耐脱水能力和吸水能力;通过增加气孔密度,提高气孔调节的敏感性,增加角质层厚度,减少水分的散失;增强耐旱性。     

土壤含水量和光照对沙地柏光合生理指标的影响

试验采用人工控制土壤水分的方法,测定不同土壤含水量条件及有效辐射强度下沙地柏苗木的蒸腾速率、净光合速率、水分利用效率等指标,分析沙地柏在不同土壤含水量和光照条件下影响的光合生理响应特征及其变化规律.土壤含水量(SWC)用称重法测定,将硬塑盆中的土壤水分含量设置为7.5％,10％,12.5％,15％,17.5％,20％ ...     

Special stomatal distribution in Sabina vulgaris in relation to its survival in a desert environment

In the semi-desert environment of the Mu Us Sandland, the vegetation is composed chiefly of shrubs and semi-shrubs, coverage normally amounting to 30-40%. However, an exception can be found in the community of Sabina vulgaris Antoine, an evergreen shrub, which tends to grow so densely that it covers the sand dunes completely. Previous research has indicated that the high density of Sabina is parallelled by the very low transpiration rate. Based on anatomical and scanning electronic microscopic observations, this paper also points out that two structural features should play an important role in the potential mechanism of water conservation in this plant. First, a low stomatal density in S. vulgaris can lead to a high stomatal resistance and low transpiration. Second, the morphological feature of S. vulgaris leaves being tightly pressed to the stems might be a structural feature of water conservation, because in this way the leaf side bearing more (and mostly larger) stomatal pores could be protected from direct high radiation, while the side with fewer (and mostly smaller) pores (the outer side) is exposed to the dry desert air.     

Differences in transpiration of Norway spruce drought stressed trees and trees well supplied with water

The paper focuses on the evaluation of transpiration as a physiological process, which is very sensitive to drought stress. Reactions of 25-year-old Norway spruce (Picea abies (L.) Karst.) trees to drought were examined during 2009 summer. Sap flow rate (SF), meteorological and soil characteristics were measured continually. Vapour pressure deficit of the air (VPD) and cumulative transpiration deficit (KTD) was calculated. During the second half of the vegetation period, the decrease in soil water content was observed and irrigation was applied to a group of spruce trees, while the second group was treated under natural soil drought. On the days, when the differences in transpiration between irrigated (IR) and non-irrigated (NIR) trees were significant (21 days), transpiration of NIR trees was only 23% of the transpiration of IR trees. We found significant differences in transpiration when the soil water content (SWC) of NIR variant at a depth of 5–15 cm ranged from 10.4 to 13.7%. Under both regimes of water availability, daily transpiration significantly responded to atmospheric conditions. However, the influence of all assessed meteorological parameters on SF of NIR trees was significantly lower than on IR tree. The dependency of transpiration on evaporative demands of atmosphere decreased with the decreasing soil moisture. Cumulative transpiration deficit of the stand during the entire evaluated period was 50.9 mm. The difference between the transpiration of the mean NIR tree and of the mean IR tree was 278.8 L over the assessed period of 47 days (5.9 L per day). The transpiration of NIR trees was 40.3% from the transpiration of IR trees during this period.     

Effects of Soil Drought and Atmospheric Humidity on Yield,Gas Exchange,and Stable Carbon Isotope Composition of Barley

The combined effects of water status, vapour pressure deficit (VPD), and elevated temperature from heading to maturity were studied in barley. Plants growing at high VPD, either under well-watered or water deficit conditions, had higher grain yield and grain filling rate than plants growing at low VPD. By contrast, water stress decreased grain yield and individual grain dry matter at any VPD. Water regime and to a lesser extent VPD affected ¹³C of plant parts sampled at mid-grain filling and maturity. The differences between treatments were maximal in mature grains, where high VPD increased ¹³C for both water regimes. However, the total amount of water used by the plant during grain filling did not change as response to a higher VPD whereas transpiration efficiency (TE) decreased. The net photosynthetic rate (P _N) of the flag leaves decreased significantly under water stress at both VPD regimes. However, P _N of the ears was higher at high VPD than at low VPD, and did not decrease as response to water stress. The higher correlation of grain yield with P _N of the ear compared with that of the flag leaf support the role of ear as the main photosynthetic organ during grain filling under water deficit and high VPD. The deleterious effects of combined moderately high temperature and drought on yield were attenuated at high VPD.     

松嫩草地全叶马兰夏季与秋季光合及蒸腾作用的比较

在生长季晴天条件下,夏季和秋季松嫩草地全叶马兰的光合,蒸腾作用的日变化均为双峰曲线,但不同季节有所差异,夏季日均净光合速率与蒸腾速率均高于秋季,光合和蒸腾作用与环境因子的植物内部因子之间有密切关系。分析表明,叶片净光合速率与有效光辐射呈极显著相关,与气孔阻力,胞间CO2呈负相关;蒸腾速率与有效光辐射呈极显著相关,与叶温,饱和差呈正相关,与气孔阻力,胞间CO2浓度呈负相关,有效光辐射是影响光合和蒸腾作用诸因子中的主导因子,而气孔阻力变化则在调节光合和蒸腾中起着重要作用,蒸腾速率午降主要由于光辐射强,叶温高,湿度低,植物体缺水,气孔部分关闭所致。     

Does transpiration control stomatal responses to water vapour pressure deficit?

Three types of observations were used to test the hypothesis that the response of stomatal conductance to a change in vapour pressure deficit is controlled by whole-leaf transpiration rate or by feedback from leaf water potential. Varying the leaf water potential of a measured leaf by controlling the transpiration rate of other leaves on the plant did not affect the response of stomatal conductance to vapour pressure deficit in Glycine max. In three species, stomatal sensitivity to vapour pressure deficit was eliminated when measurements were made at near-zero carbon dioxide concentrations, despite the much higher transpiration rates of leaves at low carbon dioxide. In Abutilon theophrasti, increasing vapour pressure deficit sometimes resulted in both decreased stomatal conductance and a lower transpiration rate even though the response of assimilation rate to the calculated substomatal carbon dioxide concentration indicated that there was no ‘patchy’ stomatal closure at high vapour pressure deficit in this case. These results are not consistent with stomatal closure at high vapour pressure deficit caused by increased whole-leaf transpiration rate or by lower leaf water potential. The lack of response of conductance to vapour pressure deficit in carbon dioxide-free air suggests that abscisic acid may mediate the response.