Transpiration Water Consumption Law And Physiological And Ecological Response Of Main Tree Species In Maolan Karst Forest

Water shortage has become a worldwide problem of human development has faced,trees in the forest transpiration water consumption of soil-vegetation-atmosphere circulation system plays an important role in the redistribution of water resources,and physiological ecology and hydrology ecological aspects of the experts and scholars have been focusing on scientific problems,and understand the advantage in the forest tree species water consumption characteristics and influencing factors is the key to solve the scientific problem.Guizhou maolan karst forest,located in the southwest of China,is the only remaining karst forest ecosystem with strong primary forest in the same latitude area of the world,and also the area with the largest distribution area of primary forest in the karst area.Aiming at this scientific problem,this study takes four dominant species of Maolan Karst forest in Guizhou Province in southwest China as the research object,and measures the transpiration water consumption of the sample tree by thermal diffusion probe method,relying on the observation and observation of the Guizhou Karst forest ecosystem.The Campbell automatic weather station on the observation tower monitors the environmental factors,and periodically measures a series of physiological indicators of the sample tree.Combined with the indoor test and analysis of the sample,the correlation analysis,stepwise regression method and principal component analysis method are used to analyze the chopping four.The transpiration characteristics of dominant tree species reveal the driving factors of transpiration,the relationship between environmental factors,biological structure and transpiration,explain the basic characteristics of the biological structure of the sample tree,compare the water consumption strategies of four tree species and drought resistance.Performance differences.The main results are as follows:1)The transpiration rate of Machilus microcarpa under different weather conditions was sunny>cloudy>rainy days,and the difference was extremely significant?P<0.01?.The daily average transpiration rate of sunny days(62.2 g·m^-2·s^-2)was 4.2 times of cloudy days(14.8 g·m^-2·s^-2),23.04 times of rainy days(2.7 g·m^-2·s^-2),and cloudy days are 5.48 times of rainy days.The annual average transpiration rate of the single plant of Machilus microcarpa was 17.93g·m^-2·s^-2.The average daily transpiration rate of each plant in each season was autumn(25.24 g·m^-2·s^-2)>summer(19.3 g·m^-2·s^-2)>spring(16.49 g·m^-2·s^-2)>Winter(10.7 g·m^-2·s^-2),the highest monthly transpiration water consumption rate appeared in October,and the average daily transpiration water consumption rate reached 44.62 g·m^-2·s^-2.2)The transpiration rate of Euonymus dielsianus shows a typical unimodal curve on sunny days.The transpiration curve is“narrow”,the cloudy day is bimodal and unimodal,and the rainy days show bimodal and unimodal curves.The curve is"wider".In three different weather conditions,the daily average transpiration rate of Euonymus dielsianus was significantly different?P<0.05?compared with other conditions.The average daily transpiration rate(2.94 g·m^-2·s^-2)on sunny days is 3.03times that of cloudy days(0.97 g·m^-2·s^-2),which is rainy days(0.75 g·m^-2·s^-2).3.92times,cloudy days are 1.29 times that of rainy days.The annual average transpiration rate of Euonymus dielsianus was 27.3 g·m^-2·s^-2,and the range was?0.97⁶1.85?g·m^-2·s^-2.The average transpiration rate per plant in each season was autumn(46.01g·m^-2·s^-2)>summer(37.52 g·m^-2·s^-2)>winter(19.8 g·m^-2·s^-2)>Spring(5.85 g·m^-2·s^-2).3)The transpiration rate of Celtis tetrandra is a typical unimodal curve,the transpiration curve is“narrow”,the cloudy day is bimodal,the rainy day shows bimodal and unimodal curves,and the transpiration curve is“wider”.In three different weather conditions,the daily average transpiration rate of Celtis tetrandra was significantly different?P<0.05?compared with other conditions.The daily average transpiration rate(2.00 g·m^-2·s^-2)on sunny days is 3.03 times that of cloudy days(1.04 g·m^-2·s^-2),which is rainy days(0.41 g·m^-2·s^-2).3.92 times,cloudy days are1.29 times that of rainy days.The annual average transpiration rate of Celtis tetrandra was 32.21 g·m^-2·s^-2,and the range was?1.39⁶6.38?g·m^-2·s^-2.The average transpiration rate per plant in each season was summer(60.57 g·m^-2·s^-2)>autumn(38.16 g·m^-2·s^-2)>spring(28.29 g·m^-2·s^-2).>Winter(1.83 g·m^-2·s^-2)>Spring(28.29g·m^-2·s^-2).4)The transpiration rate of Carpinus pubescens shows a bimodal and unimodal pattern on sunny and cloudy days,and a unimodal curve on rainy days.In the three typical weathers,the daily average transpiration rate of Carpinus pubescens was significantly different?P<0.01?compared with other conditions.The average daily transpiration rate on sunny days(60.00 g·m^-2·s^-2)is 13.82 times that of cloudy days(4.34 g·m^-2·s^-2),which is rainy days(2.31 g·m^-2·s^-2).25.97 times,cloudy days are 1.88times that of rainy days.The transpiration peaks in all three weather conditions lag behind solar radiation.The annual average transpiration rate of Yungui hornbeam was43.82 g·m^-2·s^-2,and the range was?1.2⁸8.73?g·m^-2·s^-2.The average transpiration rate per plant in each season was summer(77.84 g·m^-2·s^-2)>autumn(57.14g·m^-2·s^-2)>spring(35.82 g·m^-2·s^-2).>Winter(4.49 g·m^-2·s^-2).5)Environmental factors have a strong correlation with transpiration rate.Regardless of the conditions,Solar and VPD have a strong correlation with transpiration rate,and both have a promoting effect on transpiration.The degree of influence of solar radiation on transpiration in sunny days:sunny>cloudy>rainy days.On the sunny day,the environmental factors had the highest transpiration rate,and the rainfall and transpiration were negatively correlated,which had a certain inhibitory effect on transpiration.The soil temperature and soil moisture had different effects on transpiration due to different soil depth under different weather conditions.When measuring soil temperature,it should be measured in layers.6)Comparing the similarities and differences of transpiration rates of the four tree species under the condition of eliminating the area factor of the cutting edge.The transpiration rates of Machilus microcarpa?Euonymus dielsianus?Carpinus pubescen and Celtis tetrandra were the lowest in winter,and there was significant difference between winter transpiration and other seasons?P<0.05?.Among them,deciduous trees such as Celtis tetrandra and Carpinus pubescens.The difference between winter transpiration and other seasons is extremely significant.The transpiration rates of deciduous trees such as Celtis tetrandra and Carpinus pubescens at seasonal scale are:summer>autumn>spring>winter,which indicates that deciduous trees have similar transpiration water consumption strategies.The transpiration rate of the evergreen tree species,Machilus microcarpa and Euonymus dielsianus,was autumn>summer,indicating that the evergreen tree species also had similar water consumption strategies within a certain time horizon.The transpiration rate of different tree species in the growing season is greater than that in the non-growth season.The transpiration rate of deciduous tree species such as Carpinus pubescens tamarind and hackberry is much higher than that of evergreen tree species in the summer,but it is much less than that in winter.7)The transpiration rate,photosynthetic rate and stomatal conductance of the leaves of the sample trees were similar.The transpiration rate of the four tree species changed with the change of stomatal conductance,indicating that the stomatal conductance can directly affect transpiration.The leaf area index of each tree species has monthly and seasonal differences.The drought resistance of the four tree species was:Euonymus dielsianus>Machilus microcarpa>Carpinus pubescens>Celtis tetrandra.