植被对近地面层水热交换影响的参数化模型

应用植被对地表面与大气之间水热交换影响的参数化模型,研究了不同植被类型的覆盖度、土壤湿度下垫面的土壤温度、叶温、近地面层气温及地表面与大气之间热量和水分交换,并一相应的观测资料进行了比较,结果表明,模拟不同植被的不同植被的温湿状况、辐射特征和能量平衡关系是合理的。因此,该参数化模型可于中尺度气象模型、气候模拟和环境生态学的研究。     

玉米冠层内不同层次对光能利用的差异性

将玉米冠层分为上、中、下3个层次,分析其不同层次对光能利用的规律.结果表明:整个冠层吸收的光合有效辐射(RAR)占总入射的87.7%,其冠层的中、上层吸收比例达到75%;冠层不同层次在可见光范围内的吸收率是上层＞中层＞下层;上、中、下3层叶温日变化规律一致,不同层次的差异主要是与冠层内的小气候有关;非光化学猝灭系数(qN)与叶温、光化学猝灭系数(qp)与光合速率(Pn)的变化趋势一致;用于光化学反应的能量与用于热能转化的能量呈此消彼长的趋势.     

农田作物层温度初步研究—以冬小麦、夏玉米为例

观测表明,充分供水的麦田作物层温度在一昼夜的大部分时间内,低于作物层顶以上1.5米处气温。8—10点叶温有时比气温稍高。叶温与气温差最大值出现在日落后至露出现前一段时间内,晴日无风天气大约出现在日落后一小时。白昼,夏玉米作物层温度高于气温,冬小麦作物层温度低于气温。夜间,小麦和玉米叶温都比气温低。土壤水分不足,蒸腾速率减小,叶温升高,叶温与气温差增大。叶温的变化反映了作物自身的水分状况。     

温带混交林碳水通量模拟及其对冠层分层方式的响应——耦合的气孔导度-光合作用-能量平衡模型

利用Leuning建立的耦合的光合作用、气孔导度和能量平衡方程,以将冠层分成多层的方式,包括Gaussian五点积分法、将冠层平均分为多层的方法,逐层计算温带混交林的碳水通量,最后累加至冠层尺度,以模拟CO2和H2O通量。该模型以常规气象观测数据作为驱动变量,计算出冠层与大气之间的碳水交换,与涡动相关系统的通量观测数据进行比较,分析了不同的冠层分层方式对多层模型模拟结果的影响。从3个温带混交林通量站涡动相关系统的能量平衡闭合度来看,中国长白山站CBS、韩国GDK和日本MMF站点的能量平衡比率(EBR)分别为0.76、0.66和1.07,居于国际同类观测范围(0.34—1.2)的中上水平,因此,涡动相关系统的观测数据较为可靠。从碳水通量的日变化来看,用Gaussian五点积分法将冠层分为五层的模型能较好的模拟碳水通量的"单峰形"日变化趋势。夜间Fc为负值且变化趋势较为平缓,表明生态系统进行呼吸作用释放CO2,从日出开始Fc逐渐变为正值,表明生态系统进行光合作用吸收CO2,Fc在中午时分达到最大值,下午Fc逐渐减小,日落之后又回复到夜间的负值。H2O通量的日变化曲线与CO2通量相似,且模拟值与涡动相关实测值具有较好的一致性。在多层模型中,对冠层采用不同的分层方法,对碳水通量模拟结果有一定的影响。以Gaussian五点积分法将冠层分为五层的方法作为对照,分别将冠层平均分为2、5、10、20层的方法得到的碳水通量与其进行比较。从平均值来看,分层越多,H2O通量模拟值越低,而CO2通量模拟值越高。不同的分层方法产生的差异,主要来自于不同层的辐射吸收、温湿度、风速等环境要素的垂直廓线差异,且叶片光合作用对光的响应是非线性的。     

黄土高原苹果园不同生长阶段的小气候特征

在黄土高原苹果园内,使用小气候梯度自动测定系统于2011年1月—2013年12月定位观测果园6、3、1.5 m高度的光合有效辐射(PAR)、气温、树体温度、相对湿度以及冠层顶的总辐射和土壤10~60 cm深度的温湿度,分析了苹果园不同生长阶段的小气候特征。结果表明:总辐射、PAR、空气温度和树体温度日变化均呈单峰曲线,总辐射和PAR在12:50、空气温度和树体温度在16:00左右达到最大值;总辐射和PAR在生长盛期最强,生长始期次之;空气温度、树体温度和土壤温度在盛期随辐射变化最大,在始期次之;生长始期温度日较差最大;冠层下部PAR在生长盛期和休眠期小于冠层顶,休眠期空气温度垂直变化最大,盛期次之,除土壤表层外,其余各层土壤温度均随深度增加而升高且日变化较小;空气湿度生长盛期最大,休眠期次之,日变化呈现高-低-高趋势,冠层下部的湿度在夜间高于冠层顶部且盛期相差最为明显,生长始期其日较差最大,盛期次之;生长始期土壤含水量最高,盛期次之,表层和深层含水量较小,20 cm含水量高,但其变化幅度较大。     

玉米冠层内太阳直接辐射三维空间分布的模拟

太阳直接辐射在植物冠层内的空间分布特征影响植物生理生态功能 ,是衡量植物群体结构是否合理的重要指标。利用田间实测的玉米冠层内植株各器官的三维空间坐标进行冠层结构分析 ,将冠层内的植株器官表面划分成小面元 ;根据几何光学中光的直线传播原理 ,利用面元沿太阳光线的平行投影和投影深度排序 (Z- buffer)算法计算冠层内面元受太阳光直接照射的情况 ,建立了太阳直接辐射在玉米冠层内三维空间分布的模拟模型。模型可计算出作物冠层内任选植株的器官表面或冠层内地面上的太阳直射光斑 (Sunflecks)分布 ,也可输出选定空间位置或范围上的太阳直接辐射的分布 ,同时可实现模拟结果的三维可视化。根据此模型的模拟结果可对太阳直接辐射在玉米冠层内的空间分布进行各种分析。利用玉米冠层内光斑的三维分布测定试验 ,在光合有效辐射 (PAR)波段对模型进行了检验。模型适用于任意三维结构可测并可进行面元化划分的植物群体或个体     

森林冠层辐射的数值模拟

一、引言太阳辐射是树木和各种作物生长过程中所需能量的直接或间接源泉。一定强度的太阳辐射达到林冠层表面时,由于叶、枝等器官的吸收、反射和透射作用,使得冠层内的辐射分布有其独具的特征。本文综合考虑天空散射和叶片的内部散射作用,从辐射通量的角度在计算机上模拟了各向同性叶角分布的冠层中辐射通量的分布特征,讨论了单叶反射系数和透射系     

开放式空气C02浓度增高对水稻冠层能量平衡的影响

大气CO2浓度升高对植物冠层能量平衡的影响是导致植物生长发育和水分利用率发生变化的环境物理原因．利用位于江苏省无锡市安镇的农田自由开放式空气CO2浓度增高(FACE)系统平台,进行水稻冠层微气候和土壤热通量的连续观测,并结合能量平衡分析,研究了FACE对水稻冠层能量平衡的影响．结果表明,水稻冠层显热和潜热通量FACE与对照的差异日最大值出现在14：00左右,与空气相对湿度日最低值出现时间一致;潜热通量FACE与对照的差异日最大值变化在—15-—65J·m^-2·s^-1之间,显热通量FACE与对照的差异最低值变化在12—55J·m^-2·s^-1之间;显热和潜热通量FACE与对照的差异日最大值随冠层上方辐射平衡增加而增大．水稻冠层白天总显热通量FACE均高于对照,而总潜热通量FACE均低于对照．白天总显热和潜热通量FACE与对照的差异在同一生育期内随冠层上方净辐射增强而增大,在不同生育期随生育期推进而减少．开花期至蜡熟期,水稻冠层白天总潜热通量FACE比对照平均低6．7％．FACE使水稻冠层白天总显热通量及其占冠层上方辐射平衡的比例减少,而使总潜热通量及其占冠层上方辐射平衡的比例增大,但对土壤热通量及夜间显热和潜热通量的影响不大．开花期至蜡熟期水稻冠层白天总显热、潜热通量占冠层上方净辐射总量的比例FACE与对照之差平均为5．5％．     

基于红外热像仪的棉花水分状况诊断方法

冠层温度信息是作物水分状况诊断信号之一,红外热像仪能实时准确地获取较大区域的温度分布.本文以棉花为研究对象,针对红外热像仪获取冠层温度的主要影响因素(方位、角度和距离)开展试验,研究了不同水分处理下不同方法获取的作物水分胁迫指数(CWSI)与土壤含水率(SWC)、叶水势(LWP)和气孔导度(g_s)之间的相互关系.结果表明： 逆太阳光与冠层45°夹角获取的CWSI与SWC、LWP和g_s具有较好的相关性,是观测冠层温度的适宜方法;随着距离的增大,冠层温度会表现出衰减的现象,远距离的拍摄需要进行必要的校准工作;通过分析干湿参考表面温度与冠层温度之间的关系,提出了适合华北地区棉花水分胁迫指数的简化计算模式.     

基于塔载辐射监测帽儿山落叶阔叶林

基于通量塔常规辐射测量的宽带植被指数(BVI)具有高时间分辨率的优点,有利于获得更详细的森林冠层叶面积指数(LAI)动态信息.本文以帽儿山通量观测站的温带落叶阔叶林为例,研究宽带归一化差值植被指数(NDVI_B)、宽带增强型植被指数(EVI_B)、近红外反射率与光合有效辐射反射率比值(SR_NP)和太阳辐射反射率与光合有效辐射反射率比值(SR_SP)4种BVI时间序列的控制因子及其滤波方法,并以凋落物收集法为参考,评估采用BVI估测冠层LAI的可行性.结果表明: Huemmrich、Wilson和Jenkins 3种方法计算的同一BVI值略有不同,但其季节变化趋势高度一致.BVI主要受太阳高度角和太阳高度角与坡度夹角的影响而呈现明显的日变化,太阳高度角与坡度夹角最大时刻(12:30)前后的BVI相对稳定.晴空指数可以作为BVI日值滤波的有效参数,不同时刻数据构成的日BVI时间序列的晴空指数阈值以及滤波后的有效数据率存在差异,应综合考虑平滑效果和有效数据率选择合适的时间点代表BVI日值.NDVI_B与凋落物收集法测定的LAI呈显著的线性关系,而EVI_B、SR_NP和SR_SP与LAI均呈显著的对数关系.因此,NDVI_B在表征冠层LAI季节动态和LAI外推中更为精确、方便.鉴于大部分森林碳水通量观测塔配备能量平衡观测系统,如果同时测定光合有效辐射反射率,即可实现冠层LAI长期连续联网监测.     

Effect of tissue and atmosphere's parameters on human eye temperature distribution

A three dimensional finite element method analysis was employed to investigate the effect of tissue and atmosphere parameters namely, ambient temperature, ambient convection coefficient, local blood temperature, and blood convection coefficient upon temperature distribution of human eyes. As a matter of simplification, only eye ball and skull bone are considered as the system of eye modeling. Decreasing the local blood temperature and keeping it cool is one of the most important ways to control bleeding during surgeries. By lower temperature of body organs such as the eye, the need for oxygenated blood is reduced, allowing for an extension in time for surgery. With this in mind, this study is done to see which one of parameters, such as ambient temperature, ambient convection coefficient, local blood temperature, and blood convection coefficient, has an effective role in decreasing the temperature of the eye. To this end, 3 different paths were employed to find out about the temperature distribution through the eye. The analysis of the three paths demonstrates the interaction of ambient and blood temperature in modeling temperature changes in specific locations of the eye. These data will be important in applications such as eye surgery, relaxation, and sleep therapy.     

Comparative study of circadian variation in oral,tympanic, forehead,axillary and elbow pit temperatures measured in a cohort of young university students living their normal routines

The primary objective of the present research work is to study and compare the circadian variability in body temperature recorded from different locations of the body during subjects’ normal routines. Temperatures of oral cavity (sublingually), tympanum, forehead, axilla and the elbow pit were measured simultaneously at approximate 1-h intervals for five consecutive days during subjects’ waking span in their routine living condition. The observations were made in eight young, apparently healthy, university students. Data were analysed using cosinor rhythmometry for evaluation of circadian rhythms and two-way ANOVA with repeated measures to assess the effect of time of day and measuring site on body temperatures and their interaction. Significant circadian rhythms in body temperature, irrespective of site, were found. Based on autocorrelation analysis, it was observed that the day-to-day variability in body temperature was consistent. The acrophases of all the studied temperature rhythms were located in the afternoon, except axillary temperature, which occurred in the early evening. The mean daytime temperature was found to be the highest when recorded sublingually and it was the lowest on the forehead or elbow pit. On the basis of the results of this study, we recommend that the methods used could be introduced into laboratory courses in a curriculum of chronobiology courses for both UG and PG classes for the demonstration/study of circadian rhythms in body temperature under normal routines. The methods used are valuable as they are non-invasive, easily accepted and assessable in a student setting.     

Development of a self-contained,indwelling vaginal temperature probe for use in cattle research

A device was developed to monitor the vaginal temperature of cattle in a research setting. This device decreases labor involved with monitoring body temperature compared with manual temperature readings, allows for continuous monitoring of vaginal temperature at 1 min intervals, and also allows for temperature measurements without the presence of a human handler or without restraint, which can agitate cattle. The device consists of a blank controlled internal drug release (CIDR) device (designed by Pfizer Animal Health as an indwelling vaginal probe) that holds an indwelling vaginal temperature probe logger. The fabrication of the vaginal probe costs approximately US $325 per unit. Similar rectal and vaginal temperature responses to lipopolysaccharide challenge were observed when vaginal and rectal temperatures were measured simultaneously in the same heifer (P>0.05). Additionally, rectal and vaginal temperatures were highly correlated (r=0.97; P<0.0001). Similar to the rectal temperature monitoring device, the vaginal device allows for the measurement of vaginal temperature without the potential biases associated with the stress response produced as a reaction to the handling by and (or) presence of humans. The vaginal temperature recording device will provide researchers with an additional inexpensive tool to study physiological responses in female cattle.     

Comparison of daily rhythm of rectal and auricular temperatures in horses kept under a natural photoperiod and constant darkness

The aim of this study was to assess the accuracy of auricular temperature (AT) recording in the determination of body temperature as well as rectal temperature (RT). For this purpose we compared RT and AT in five clinically healthy horses. Data collections were performed every 3 h over 2 different 24 h photoperiods, 13/11 light/dark cycle and constant darkness. Repeated measures multifactor analysis of variance (MANOVA) was applied to determine a statistical significant effect of time of day, side of temperature collection and photoperiods on AT and RT. Our finding showed a significant effect of time of day on the temperature values recorded and an influence of side of temperature collection. RT values were higher of about 4 °C than the AT values, and the pattern of the two temperatures was not comparable. A daily rhythmicity of rectal temperature was observed. Auricular temperature no showed daily rhythmicity in both periods of monitoring. On the basis of these findings AT does not reflect body temperature as well as RT in horse.     

The use of percutaneous thermal sensing microchips for non-invasive measurement of body temperature in foals during summer seasons in a subtropical region

Continuous accurate attainment of the body temperature of foals is important to detect early stages of severe heat stress or fever due to a systemic illness. Among a number of methods to measure body temperature, measuring rectal temperature with a digital thermometer is most frequently used due to being relatively fast and simple method. It is also comparatively accurate and correlates well with the core body temperature. However, this method requires restraining the foal for a few seconds to obtain the temperature, and it can be dangerous for the handling person. Percutaneous thermal sensing microchips (PTSMs) are a means of monitoring the body temperature of horses, which offers a non-invasive, hygienic, quick, and accurate way to measure body temperature and provide an identification number for each individual, once it is implanted. This study tested the hypothesis that PTSM has a strong relationship with a conventional body temperature measurement, i.e., measuring rectal temperature with a digital thermometer of foals during summer seasons. Thirty-two foals in three consecutive foaling seasons (2018, 2019, and 2020 season) were implanted a PTSM into the right pectoral muscle, the right splenius muscle, the right gluteal muscle, and the nuchal ligament as early as two weeks after birth. The four PTSM temperatures, rectal temperature, and climate conditions (air temperature, relative humidity, and wet-bulb globe temperature) were obtained simultaneously during the three summer seasons and paired for comparison analysis. Among the PTSM temperatures, the pectoral muscle had the highest correlation and the least differences with rectal temperature. Using PTSM was safe, easy, and reliable for attaining body temperature in foals.     

A study of human skin and surface temperatures in stable and unstable thermal environments

Skin temperature is a common physiological parameter that reflects human thermal responses. The purpose of this research was to investigate the effects of radiant temperature on human skin temperature and surface temperature in stable and unstable thermal environments. For a clothed human body, the skin temperature is the surface temperature of the skin, while the surface temperature is the outer surface temperature of the clothes. For this aim, the radiant temperature from 26 to 38 °C and then from 38 to 26 °C was controlled in three different ways; in stable condition keeping stable above 40 min, in unstable condition at a rate of 2 °C/5 min, and in another unstable condition at a rate of 2 °C/10 min. Experimental data showed that at the same radiant temperature, the local skin/surface temperatures during the radiant temperature decrease were higher compared to those during the radiant temperature increase. During the radiant temperature increase/decrease, the increments/decrements of the mean skin temperature and the mean surface temperature decreased gradually from the stable condition, 2 °C/10 min to 2 °C/5 min. Compared to surface temperature, the faster the radiant temperature changed, the more obviously the change in skin temperature was delayed. These data demonstrated that the human body has physiological adaptability to unstable thermal environments.     

Daily thermal preference variation of the sand recluse spider Sicarius thomisoides (Araneae: Sicariidae)

Preferential temperature as a physiological feature is crucial for spiders, since it determines the selection of key habitats for their survival and reproduction. In this work, we study the daily and geographical variation of the preferential temperature of the spider Sicarius thomisoides subjected to different degrees of daily thermal oscillation in their habitats. Preferred temperatures differ between coastal and inland populations, but in both cases, there is a marked bimodality in the daily pattern of temperature preference, with two peaks per day that would be given by the changes in the hours of activity. These nocturnal spiders select higher temperatures in the evening (active period) and select lower temperatures during late morning (resting period). In laboratory, spiders have preferred temperatures that differ from those found in their habitats, so they must tolerate or compensate non-preferred temperatures by active thermoregulation in natural conditions.     

Body Temperature Changes in Free-ranging Baboons (Papio hamadryas ursinus) in the Namib Desert, Namibia

We surgically implanted temperature sensitive telemeters intraperitonealy in free-ranging baboons. Thereafter, we recorded body temperature changes while the baboons were free-ranging and under visual observation. Two distinct patterns of daily body temperature fluctuations occurred; they were related to the availability of drinking water. Core body temperature fluctuated by as much as 5.3°C and regularly exceeded 41°C. Behavioral adaptations of the baboons, notably sandbathing, appeared to be associated with the regulation of body temperature.     

Effect of temperature on drought resistance and growth of cotton plants

In cotton plants ( Gossypium hirsutum L. cv. B.J.A.) the temperature of the roots affected both root and shoot growth, as did the temperature of the shoot. Drought resistance increased when the temperature imposed on roots (27°C) was lower than that imposed on shoots (17°C); the result was a decrease in both transpiration and flow of root sap. Stomatal characteristics as measured by density, index and resistance, depended only on shoot temperature. Differences in drought resistance, depended only on shoot temperature. Differences in drought resistance seem to be a result of changes in transpiration flow modulated by the amount of absorbed water.     

连续温度梯度下昆虫趋温性的研究现状与展望

昆虫作为一种能够自由活动的生物,可以通过运动主动选择对其有利的环境温度。大多数研究中昆虫被迫接受人为设定的恒温或变温,并未体现出昆虫本身对适宜温度的主动选择性。连续温度梯度是在某一介质的两端产生由高到低连续变化的温度范围。在一定温度梯度中昆虫趋温行为的研究揭示了其主动选择的适宜温度,这对了解昆虫的空间动态、提高测报准确性和开发防治新方法有重要意义。总结了产生连续温度梯度的各种装置,致冷、加热和温度测量方法以及昆虫趋温行为的观察装置和方法,包括在植物体上(内)及空气、下垫面、粮食和土壤等介质中产生温度梯度的方法及装置。各装置以水浴或电器设备制冷或加热,肉眼观察手工记录或以摄像机、声音信号采集系统等方法记录昆虫的行为。综述了多种昆虫生长发育、栖息、产卵或取食的偏好温度,总结了性别、发育阶段和生态型等生理因素及光照、湿度和预适应温度等环境因子对昆虫偏好温度变化的影响。昆虫的趋温性因种而异,同种昆虫不同发育阶段或不同生命活动所趋温度不同。多数种类昆虫雄性成虫的偏好温度比雌性略高。某些昆虫的多型现象可能导致其种内不同生态型的偏好温度存在差异。光照和湿度的变化会影响某些昆虫对温度的反应。有些昆虫经预适应温度训练后,其偏好温度发生改变。某些昆虫对温度的偏好呈现出一定的日变化和季节变化规律。饥饿条件下昆虫的偏好温度降低。温度梯度的有无及其方向、温度的高低、温差的大小等因素都会影响昆虫的活动性。最后分析了本类研究中存在的问题和不足,并展望了未来的研究方向,指出开展对重要农林作物害虫和天敌趋温行为及其生理学机制,外界环境因素影响昆虫趋温性等方面的探索将是未来该领域研究的重点内容。