|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.|