高寒矮嵩草草甸植被蒸散的研究

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	高寒矮嵩草草甸植被蒸散的研究
	沈振西
学位类型	硕士
导师	周兴民
	1997
学位授予单位	中国科学院西北高原生物研究所
学位授予地点	中国科学院西北高原生物研究所
学位专业	植物生态学
关键词	矮嵩草草甸蒸渗仪蒸散蒸腾水分利用效率
摘要	本研究主要利用大型蒸发渗漏仪（Lysimeter）研究了高寒矮嵩草草甸植被的蒸散量、蒸腾量、丛间蒸发量、潜在蒸散量以及植被水分利用效率，分析了影响蒸散的气候因子和土壤水分状况。结果表明：矮嵩草草甸的热量状况随季节的变换呈现有规律的波动。其中气温和太阳总辐射从5月份持续升高到7月，达到高峰期，之后又逐渐开始下降。降水量在5、6、7月份比较稳定，差异较小，8月份为降水量的高峰期，9月降水量锐减。水热条件基本同步。矮嵩草草甸0－20厘米的土层是蒸散耗水的主要土层，30－50厘米土层的土壤含水量一直处于高而稳定状态。5月份为矮嵩草草甸土壤的湿润期，土壤含水量在整个生长季内最高，6、7月为土壤水分的消耗期，是土壤含水量的最低时期，土壤含水量在8－9月份又逐步回升，整个季内土壤含水量呈现“V”型分布。矮嵩草草甸生长季内植被蒸散量的日平均值为3.55毫米，其中5月份最低（2.515毫米），6、7月份达最高峰期，分别为4.231毫米和4.104毫米，7月以后逐渐降低。月蒸散总量与月降水总量的差值在5、6、7、9四个月为负值，蒸散量大于降水量，其中，9、6、7三个月的负值较高（-45.12－-51.32mm），唯有8月份差值为正值（8.38)。蒸散的日进程是明显的单峰曲线，从晨8：00开始快速升高，在12：00－14：00间达到高峰值，之后开始缓慢下降。植被的蒸腾量随LAI的增大而增加，而植被的丛间蒸发量则随着 LAI 的增大而减少。TP／Ea在5月份最低（0.18），到8月份达最大值（2.72）。植被的潜在蒸散量（EP）从5月份逐渐增大，到8月达到最高值，8月以后至9月骤然降低。植被的耗水系数ET／Ep) 在6月份最大（0.81），在5 - 9月间耗水系数在0.55-0.81间波动，平均耗水系数为0.7。水分平衡法计算的蒸散量低于 Lysimeter实测值，平均误差为15.87%, 但它们之间相关性极显著。矮嵩草草甸植被的水分利用效率（WUE）在6月份最高（14.22 kg/ha. mm），7月次之（5.20kg/ha. mm），5月最低（2.84kg/ha. mm），6、7月份是植被需水的敏感期。矮嵩草草甸植被平均 WUE（7.05 kg/ha. mm）较低。
其他摘要	In this paper the author mainly studied on evapotranspiration (ET), transpiration (TP), evaporation (Ea), potential evapotranspiration (Ep) and water use efficiency (WUE) in Kobresia humilis meadow, and analysized dynamics of the climate factors and soil moisture content, also compared the Lysimeter'method and water balance method and calibrated the vegetation coefficient in improved Penman model. The result were as fllow: Heat factor as a driving force for evapotranspiration which has regular changed during the growing season, air temperature and total solar radiation formly increased from May, and reached its peak period in July, and then gradually declined to September. Precipitation was no evidently difference from may to July, but it was highest in August during the growing season. Soil layer in 0-20cm depth was an important layer of water consumpation. Soil moisture content in the layers below 30cm kept high percentage and little difference, it exceeded the field capability in some days. The moistest period of soil was in May, the lowest period was in June and July, soil moisture content was increased again in September. Soil moisture content showed "V" pattern from May to September. The daliy average ET was about 3.55mm/day during the growing season, and appeared the minimum about 2.515 mm/day in May, reached the maximum about 4.231 mm/day in June, and reduced after July. The difference values between monthly total ET and precipitation was negative in May, June, July and September, the value was around-45.12 - -51.32mm/month, but it showed positive value about +8.38 in August. The diurnal courses for ET showed significently single peak curves, maximum ET occured between 1200 and 1400. Transpiration (TP) and Evaporation (Ea) was close related to leaf area index (LAI), Ea begun to level off as LAI begun to rapidly increase as evidenced by the rate of TP, this occured in July shortly after canopy closure. The ratio of TP to Ea (TP/Ea) was only 0.18 in May, and maximum was 2.72 in August. Potential evapotranspiron (Ep) was estimated by improved Penman model increased steadily to maximum in August from May, shortly after August it decresed sharply in September. The ratio of ET to Ep (ET/Ep), the coefficent of water consumption, reached maximum in June, and fluctuated from 0.55 to 0.81, the Average value was 0.70 during growing season. Evapotranspiration determined by water balance method was lower than that by Lysimeter'method, although the mean error was about 15.87%, there was significant correlation between the two methods. The average Water use efficiency (WUE) of K. humilis meadow was fairly low (7.05kg/ha. mm) due to the lower total dry matter production, coresponded with highest rate of dry matter accumulation the maximum of WUE occured in July about 14.22kg/ha. mm, and the minimum of WUE was in May about (2.84kg/ha. mm), so considered July was critical water demand period for vegetation.
页数	55
语种	中文
文献类型	学位论文
条目标识符	http://210.75.249.4/handle/363003/3360
专题	中国科学院西北高原生物研究所
推荐引用方式 GB/T 7714	沈振西. 高寒矮嵩草草甸植被蒸散的研究[D]. 中国科学院西北高原生物研究所. 中国科学院西北高原生物研究所,1997.

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