平茬措施对人工梭梭树干液流的影响及其与气象因子的关系

Effects of stumping on sap flow of artificial Haloxylon ammodendron and its relationship with meteorological factors

【目的】揭示梭梭平茬后生长过程中的水分传输规律及水分利用过程,为今后人工梭梭林的抚育管理提供技术支撑及理论依据。【方法】利用PS-TDP8树木茎流监测系统和自动气象站对乌兰布和沙漠平茬与未平茬梭梭的液流及其气象因子进行测定。【结果】平茬与未平茬梭梭晴天茎干液流日变化呈单峰型,雨天茎干液流日变化呈双峰型,雨天液流峰值、夜间液流速率低于晴天;平茬梭梭液流启动时间及峰值出现时间均晚于未平茬梭梭;平茬与未平茬梭梭液流日累积过程曲线呈“S”型,符合典型生物生长曲线,平茬梭梭与未平茬梭梭晴天的日累积液流量高于雨天;平茬与未平茬梭梭树干液流均与太阳总辐射、空气温度、风速呈正相关,与空气相对湿度呈负相关,液流速率的启动时间、峰值出现时间与气象因子存在时滞效应;在小时尺度上,平茬梭梭气象因子进入的顺序为太阳总辐射(T_(R))、空气温度(T_(a))、风速(W_(S))、空气相对湿度(R_(H)),可以共同解释液流速率变化的83.6%,TR可单独解释液流速率变化的81.1%,T_(a)可单独解释液流速率变化的2.0%;未平茬梭梭气象因子进入的顺序为T_(R)、W_(S)、T_(a)、R_(H),可以共同解释液流速率变化的70.0%,TR可单独解释液流速率变化的60.3%,WS可单独解释液流速率变化的7.9%;在小时尺度上,平茬梭梭与气象因子的回归方程为Y=-0.947+0.002T_(R)+0.034T_(a)+0.207W_(S)-0.007R_(H),未平茬梭梭与气象因子的回归方程为Y=0.723+0.001T_(R)+0.197W_(S)+0.018T_(a)-0.005R_(H),均达到极显著水平(P<0.01)。【结论】在小时尺度上,对平茬梭梭树干液流速率的影响最大的是太阳总辐射、空气温度,对未平茬梭梭树干液流速率的影响最大的是太阳总辐射、风速,平茬梭梭、未平茬梭梭与气象因子的回归方程能够较好地解释小时尺度上树干液流变化与气象因子的关系。研究结果对于明确梭梭平茬后生长过程中的水分传输规律具有重要意义,为人工梭梭林的抚育管理提供数据支撑及理论依据。

【Objective】Reveal the water transfer law and water utilization process during the growth process of Haloxylon ammodendron(C.A.Mey.)Bunge,provide technical support and theoretical basis for the future tending management of Haloxylon ammodendron(C.A.Mey.)Bunge.【Method】The sap flow of artificial Haloxylon ammodendron(C.A.Mey.)Bunge of stumping and no stumping and their affecting meteorological factors in the Ulan Buh desert,were tested and observed by using the PS-TDP8 sap flow testing system and automatic meteorological station.【Result】On sunny day,the daily variation curve of the stem sap flow of stumping and no stumping Haloxylon ammodendron(C.A.Mey.)Bunge is in a unimodal distribution,on rainy day,the daily variation curve of the stem sap flow of stumping and no stumping Haloxylon ammodendron(C.A.Mey.)Bunge is in a bimodal distribution,peak liquid flow in rainy days and liquid flow rate at night are lower than in sunnydays.The stem sap flow start time and peak occurrence time of the stumping were later than those of the no stumping.The curve of the daily accumulation process of stumping and no stumping flow is“S”shape,which is in line with the typical biological growth curve.The daily accumulated liquid flow of stumping and no stumping is higher on sunny days than on rainy days.The sap flow of Haloxylon ammodendron stumping and no stumping is positively correlated with total solar radiation,air temperature and wind speed,and negatively correlated with relative humidity of the air.There is a time lag effect on the start time,peak time and meteorological factors of liquid flow rate.On an hourly scale,the order in which the meteorological factors of the stumping enter is TR,Ta,WS,RH,which together can explain 83.6%of the change in flow rate,TR alone can explain 81.1%of the change in flow rate,Ta can alone explain the 2.0%of change in flow rate.The order of entering the meteorological factors of the no stumping is TR,WS,Ta,RH,which together can explain 70.0%of the change in flow rate,TR can explain 60.3%of liquid flow rate change alone,WS can explain 7.9%of liquid flow rate change alone.On an hourly scale,the regression equation between the stumping and the meteorological factors is Y=-0.947+0.002 T_(R)+0.034 T_(a)+0.207 W_(S)-0.007 R_(H),and the regression equation between no stumping and the meteorological factors is Y=0.723+0.001T_(R)+0.197 W_(S)+0.018T_(a)-0.005R_(H),all reached extremely significant levels(P<0.01).【Conclusion】On an hourly scale,the greatest impact on the sap rate of Haloxylon ammodendron is the total solar radiation and air temperature,the greatest influence on the sap rate of Haloxylon ammodendron is the total solar radiation and wind speed,the regression equations of stumping and no stumping and meteorological factors can better explain the relationship between hourly scale trunk sap changes and meteorological factors.The research results are of great significance for clarifying the law of water transfer during the growth process of Haloxylon ammodendron,and provide data support and theoretical basis for the tending management of Haloxylon ammodendron.