Water consumption of a six-year-old river red gum plantation in the Southern Zagros Mountains, Iran

Water is the most important limiting factor in the development of arid environments; therefore, optimization of water use is a necessity in desert reclamation projects. Evapotranspiration of a 6-year-old river red gum (Eucalyptus camaldulensis Dehnh.) plantation, located in a sedimentation basin of an artificial recharge of the Gareh Bygone Plain groundwater system in Iran’s southern Zagros Mountains, was studied during a 7-month period. A neutron moisture probe was used to monitor soil water changes in the root zone. Soil water depletion following rapid drainage for blocks receiving relatively high, medium and low volumes of floodwater were 809.6, 312.4, and 203.1 mm, respectively, for a 150-day period. Soil water potential during most of the study period was below -1.5 MPa. This study proves that river red gum in not a suitable species for desertification control where water conservation is of vital importance. Flood irrigation of trees on 8 Aug. 1991 provided the opportunity to throw doubt upon the claim of summer dormancy of river red gum.     

新疆2023年夏季高温的阶段性特征及环流演变

2023年夏季(6-8月)新疆平均气温偏高幅度居1961年以来第一位,高温日数居历史同期第一位,高温过程持续时间居历史同期第一位,高温覆盖面积最广。本文利用新疆105个国家级气象站监测资料,分析2023年夏季高温日数、最高气温、高温过程时长和高温过程覆盖范围等极端性特征的季节内演变,季节内各月高温特征总体呈现发展-强盛-消减的趋势,并运用NCEP/NCAR联合制作的位势高度场再分析资料对2023年夏季100hPa、500hPa层面高空环流的阶段性变化对比研究得出,新疆极端高温的季节内变化与南压高压和伊朗副高的强度、面积、位置的阶段性变化密切相关,当南压高压偏东偏北,强度偏强,伊朗副高增强,北移东进,青藏高原高压脊发展强盛,配合西太副高位置东伸,有利于新疆产生持续性极端高温天气过程。当南压高压为青藏高原型,伊朗副高主体位置偏西,有利于冷空气从北方进入新疆,造成阶段性降温天气,新疆极端高温过程减弱,持续时间缩短。