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干旱区绿洲农田防护林耗水规律研究
付帅
学位类型博士
导师罗毅
2016
学位授予单位中国科学院大学
学位授予地点北京
学位专业自然地理学
关键词玛纳斯绿洲 农田防护林 蒸腾耗水 冠层导度 水资源管理
摘要干旱区绿洲防护林是绿洲农业生态安全的维护屏障,具有改善近地面气候条件、减少或消除风沙危害、促进植被恢复和提高绿洲生产力等功效。在气候条件和人类活动等综合影响下,玛纳斯流域绿洲出现地下水位下降严重、降雨量减少等现象,绿洲内农田防护林出现大面积衰退现象,威胁着绿洲农林系统的持续稳定发展。本研究以气象要素变化和土壤水分变化为出发点,分析玛纳斯绿洲农田防护林主要树种小叶杨的边材液流变化规律、蒸腾耗水和冠层导度特征,探索该区域林木蒸腾耗水的影响因子与林木耗水的关系,寻找农田防护林衰退的原因;通过冠层导度和冠层蒸腾模拟,辨明影响因子与冠层导度和冠层蒸腾的关系;在水资源协调策略上,通过构建SPAC模型,模拟不同林龄及灌溉管理制度下农田防护林的水量平衡,提出相应的的灌溉管理策略;最后探讨玛纳斯流域绿洲农林生态系统水资源管理的结构和模式,建议玛纳斯河流域绿洲农田水资源的合理配置。 通过研究得出以下主要结论:(1)太阳辐射、空气温度、风速与水汽压亏缺与防护林蒸腾耗水呈正相关,而相对湿度与林木蒸腾耗水呈负相关,并可用多元线性方程描述:Tr=0.034T-0.027RH+0.26W-0.150P+0.029R+3.197,R2=0.86。 (2)在整个作物生长季,从日尺度考虑,气孔调节在控制防护林蒸腾耗水中占据主导地位。在土壤干旱、极度干旱和湿润的情况下,环境因子在中午对防护林蒸腾耗水的控制起主要作用,并且控制作用呈现出湿润>极度干旱>干旱;而在日进程中,气孔对蒸腾耗水控制的强度上午最高,并逐渐下降,中午时达到最低,而后下午控制强度逐渐提升,呈现出‘U’型变化趋势,相反,环境对蒸腾耗水的控制呈现出一个倒‘U’型。 (3)农田防护林小叶杨冠层导度也受到太阳辐射、水汽压亏缺、相对湿度、温度、风速和土壤水分影响。冠层导度与太阳辐射存在很好的正相关,在0.01水平上相关系数达到0.47,而与空气相对湿度和水汽压亏缺存在明显的负相关,相关系数分别为-0.614和-0.358(0.01)。冠层导度与太阳辐射成幂指数关系:gc=a*ebRn,与空气相对湿度的关系体现为方程:gc=-a*Ln(RH)+b,与水汽压亏缺的关系表现为:gc=-a*Ln(VPD)+b,而风速与冠层导度之间则具有二项式的关系:gc=a*wind2 + b*wind +c,冠层导度与土壤水分关系表现为分段函数特征,关系为:gc=gcmax/[1+(REW/REW50)k],REW低于0.4时,冠层导度迅速下降。 (4)基于Jarvis冠层导度计算公式与Penman-Monteith蒸散计算公式,建立了防护林蒸腾耗水模型,检验结果表明,模型可有效计算不同土壤水分和气象环境下的林木蒸腾耗水。基于此模型,本研究给出了玛纳斯河绿洲不同林龄杨树防护林在不受水分胁迫条件下的蒸腾耗水量计算公式:Tr=847-844/[1+(x/87.9)1.9] (Tr:年蒸腾耗水量;x:树龄),并给出了土壤水分胁迫下蒸腾耗水的变化规律:土壤有效含水量(REW)的关系:Tr=Tr1/[1+e-60.67*(REW-0.402)](Tr:不同REW下蒸腾耗水量;REW:土壤有效含水量)。 (5)基于农田防护林系统水分运动构建农田防护林SPAC模型,经实测数据检验,模型能够较好地反映防护林土壤水分动态与蒸腾耗水规律;情景分析显示玛纳斯河绿洲,从幼期到成熟期的年灌溉额度分别是352mm、398.5mm、432mm和398.5mm,选择次灌溉量分别是30mm、60mm、90mm和90mm。
其他摘要Farmland shelterbelt provides an ecological protection screen for oasisagriculture,it improves the surface climate conditions, decreases or eliminates the hazards of sand storms, promotes the vegetation restoration and increases the effectiveness of oasis productivity.In current climate conditions, comprehensive with the influence of human activities, water resources in the oasis of Manas river basin showed shortage, such as groundwater serious drawdown, rainfall decreased. Oasis farmland shelterbelt was in a massive recession phenomenon, which was threated to the steady development of oasis agroforestry system. In this study, coupled with meteorological factors, soil moisture and groundwater to analysis sapflow, transpiration, water consumption and canopy conductance characteristics of Populus simonii Carr, the main tree species in the farmland shelterbelt of Manas oasis; and discusses the relationship between water consumption and influence factorsin the farmland shelterbelt, and get the causing of farmland shelterbelt decline. Base on the canopy conductance(gs) and canopy transpiration model, to identify the impact factors effect on canopy conductance and transpiration; For setting water resources coordination strategy, we structured a SPACmodel, simulated water balance and irrigation managemen under different forest age and different soil water storage, and then propounded irrigation management strategy; In the Final,Expounded agriculture and farmland shelterbelt water management structure in the oasis, proposed water resources rational allocation. The manily research results are: (1)Solar radiation, tempetature, wind and VPD promoted farmland shelterbelt transpiration, but relative humid inhibited trees transpiration in the shelterbelt. And a linear regression equation has well expressed the relationship between transpiration and the meteorlogical factors: Tr=0.034T-0.027RH+0.26W-0.150P+0.029R+3.197,R2=0.86. (2) Throughout the growing season, stomatal play the dominate role in controling shelterbelt transpiration on day scale. Under different levels of soil moisture drought, environmental factors plays themain role in controlling shelterbelt transpiration in noon, and followed: wet > extreme drought > drought;and on the hour scale, the strength of the stomatal controlling transpirationshowed:peaked in the morning, decreased to noon, then increased to get another peak, presents a U-shaped trend, and environment control of the transpiration water consumption, by contrast, show an inverted U-shaped. (3) In farmland shelterbelt, canopy conductance was influenced by solar radiation, VPD, relative humid, tempetature, wind and soil water. Canopy conductance was positive correlated with solar radiation, and correlation coefficient was 0.47 at the level of 0.01; but it showed negative correlationship with relative humid and VPD, and got correlation coefficient with -0.614 and -0.358(0.01). And the relationship between them showed: Rn presented significant relationship with gc, through an exponential equation (gc = a*ebRn). VPD and RH showed logarithmic equation gc=-a*Ln(VPD)+b, and gc= -a*Ln(RH)+b. And wind spead shows a quadratic polynomial equation gc = a*wind2 +b*wind+c.Canopy conductance relation with soil moisture characteristics by a piecewise function of:gc=gcmax/[1+(REW/REW50)k], when the value of REW was below 0.4, canopy conductance dropped rapidly. (4) According to measured data, we constructed Jarvis canopy conductance model, parameterized and verificated it, and used modeled canopy conductance to modle transpiration based on Penman-Monteith equation, both the canopy conductance model and transpiration model played well in the study area, they arereliable and feasible. According to the model, thetranspiration characteristic of shelterbelt in different tree ages with no water stress showed:Tr=847-844/[1+(x/87.9)1.9] (Tr:transopiration with no water stress;x:tree ages); and the relationship between transpiration and soil moisture was:Tr=Tr1/[1+e-60.67*(REW-0.402)](Tr:transpiration under different REW,REW:relative extractable water). (5)We simulated the farmland shelterbelt water balance and irrigation management by structured SPACmodel after calibration and verification. We found that deep infiltration water accounted above 18% of farmland shelterbelt water consumption from 2013 to 2015. For farmland shelterbelt keeping them away from soil water stress from young to mature, the irrigation quota should be 352mm, 398.5mm, 432mm and 398.5mm,and the suitable irrigation strategy of them were 30mm、60mm、90mm and 90mm.
学科领域自然地理学
语种中文
文献类型学位论文
条目标识符http://ir.xjlas.org/handle/365004/14700
专题研究系统_荒漠环境研究室
作者单位中科院新疆生态与地理研究所
推荐引用方式
GB/T 7714
付帅. 干旱区绿洲农田防护林耗水规律研究[D]. 北京. 中国科学院大学,2016.
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