摘要:
In order to know the microclimate of the habitat shrubs in the arid and semi-arid area,choosing clear and gentle breeze day,we measured the leaf temperature of Quercus vaviabilis seeding under vervain family and in bare land.At the same time we made a contrast with the high temperature stress index to analyze the nursing effect of Vitex negundo var. heterophylla. The results showed that the leaf temperature of Quercus variabilis seeding was clear different between under vervain family and in bare land,especially the northern part point under canopy was lower than the bare land's. We found the leaf temperature changed little during the observation period,the leaf temperature of Quercus variabilis seeding shaded by vitex shrub was lower than the external natural condition,and vitex shrub had a significant effect on Quercus variabilis seeding nursery shading.There was an evident difference in the leaf temperature between the northern and the southern of shrub. The leaf temperature of southern part point under canopy was higher than the northern at noon.During the summer solstice,this difference was more obvious, and the leaf temperature was much more than the HTSI,but the duration was short at this time.Whether under vitex shrub or in bare land,the trend of leaf temperature change between Quercus variabilis seeding and the air temperature were same,but air temperature was between leaf temperatures of Quercus variabilis in the northern and the southern of canopy.The paper pointed out that Quercus variabilis leaf temperature in natural conditions was about 1°Cin spring and increased about to 2°Cor 3°Chigher than HTSI,and the time lasted 1 h to 4 h everyday.The leaf temperature of southern part point under canopy was greater than HTSI in some cases and the average difference was 4.6°Clasting for 1 h to 2 h.%为了解干旱半干旱地区生境中现有灌木植物群丛形成的微气候,有效利用荆条灌丛对冠下栓皮栎幼苗的荫庇作用,选择晴朗无风或微风试验条件,用红外热成像仪测定荆条灌丛下和无荆条荫庇对照下的栓皮栎幼苗叶温,并与栓皮栎幼苗叶片高温胁迫指标对比,分析遮阴减少高温胁迫的程度和时间.结果表明:荆条灌丛下与对照下栓皮栎幼苗叶温有明显差异,特别是荆条北1/2栓皮栎幼苗叶温明显低于对照下叶温,且叶温在观测期内变化幅度小;荆条南北栓皮栎叶温也有明显差值,荆条南部12:00时因阳光与枝倾角相近,光线透射,叶温差值最大,夏至日附近表现最明显,超过高温胁迫指标较多,但持续时间短;在荆条庇荫下,或在自然状态下,栓皮栎幼苗叶温与气温的变化趋势相同,但气温整体位于荆条灌丛南北侧叶温之间;自然条件下,栓皮栎叶温超过高温胁迫指标的程度逐渐增加,从春季的1°C左右,增加至夏季的2~3°C,时间从1h变化到4h.荆条灌丛下南1/2栓皮栎幼苗叶片中午前后有明显的光斑而出现高于高温胁迫指标的情况,平均高出4.6°C,持续时间1~2h;荆条荫庇的区域栓皮栎幼苗叶温均低于高温胁迫指标.