Sap flow variation of Haloxylon ammodendron under different pruning treatments and its influencing factors
This study focuses on the real-time dynamic monitoring of meteorological factors and sap flow rates of Haloxylon ammodendron subjected to different pruning treatments in the northeast part of the Ulan Buh Desert.The sap flow characteristics of Haloxylon ammodendron at different time scales during the vigorous growth season(from June to August)under different pruning treatments were investigated and their responses to meteorological factors were examined.Water consumption model in relation to meteorological factors was established to reveal the patterns of water transportation in Haloxylon ammodendron after pruning.Thermal diffusion sap flow meter and automatic weather station were used to monitor the sap flow in Haloxylon ammodendron subjected to different pruning treatments and solar radiation,air temperature,relative humidity and vapor pressure deficit.Sap flow rates in Haloxylon ammodendron under different pruning treatments(120 cm pruning,90 cm pruning,60 cm pruning)exhibited a"broad peak"pattern on sunny days,while unpruned Haloxylon ammodendron displayed a"single-peak"pattern.On rainy days,sap flow rates fluctuated dramatically,presenting an"irregular multi-peak"curve,which are lower compared to those of sunny days.The daily average sap flow rates in unpruned,120 cm pruned,90 cm pruned and 60 cm pruned Haloxylon ammodendron were 2.314 6,3.333 4,1.333 3 and 0.767 2 cm/h,respectively.The daily water consumptions were 8.62,13.43,2.40 and 2.89 kg/d,respectively.On the hour scale,solar radiation was the primary factor influencing sap flow rates in both pruned and unpruned Haloxylon ammodendron.On the daily scale,solar radiation was the main factor affecting sap flow rates in 90 cm pruned and unpruned Haloxylon ammodendron,while air temperature influenced sap flow rates in 120 cm pruned Haloxylon ammodendron and wind speed affected sap flow rates in 60 cm pruned Haloxylon ammodendron.On the month scale,water consumption in 120 cm pruned Haloxylon ammodendron was mainly influenced by solar radiation and air temperature,water consumption in 90 cm pruned Haloxylon ammodendron was primarily influenced by relative humidity and solar radiation,and water consumption in 60 cm pruned Haloxylon ammodendron was mainly influenced by wind speed.With the increase in time scale,the number of meteorological factors included in the model decreased,and the explanatory power for sap flow decreased.The fitted equations in this study reached significant levels and can predict the transpiration characteristics of Haloxylon ammodendron at different time scales.The results of this study are of great significance for understanding the patterns of water transportation in Haloxylon ammodendron after pruning.
万方数据
维普
