Research On Transpiration Water Consumption Of Main Tree Species In The Kanas National Nature Reserve

Kanas National Nature Reserve locates in the northwest Altai Mountain,Xinjiang.It has important functions in improving environment and climate,keeping balance of ecosystem.The Taiga forest types here is a special forest type in China,and its dominant tree species are Larix sibirica Ledeb.,Picea obovata Ledeb.,Abies sibirica Ledeb.,and Pinus sibirica（Loud.）Mayr.,Betula pendula Roth.is mainly distributed in the lower altitude.Sap flow,transpiration,and photosynthesis of these trees species were measured by FLGS-TDP and LI-6400 respectively,during the growing season（June to September）.Simultaneously the relationship among the sap flow,transpiration and photosynthetic rate were be analyzed.The results showed that:（1）In growing season,Curves of the stem sap flow of all sample trees were day higher in a day and lower in night.The sap flow velocity of larger diameter class was significantly higher than that of small diameter class.The changes of the stem sap flow of sunny side were consistent with the shade side to all sample trees.But the stem sap flow of sunny side starting time and peak time were earlier than the shade side’s,and also their peak of stem sap flow and daily average sap flow were high than the shade side’s.（2）In different weather conditions,the order of daily average sap flow velocity of sample trees was that of sunny>rainy>cloudy,not including the trees of diameter classⅡ,diameter classⅢ,and diameter classⅣwhich were,in the of rain>sunny>cloudy.（3）Changes of all trees’stem sap flow velocity were significantly different during the growing season.The order of stem sap flow velocity of diameter classⅠandⅡof P.obovatas,diameter classⅠandⅡof P.sibirica were showed July>August>June>September.the order was that June>July>August>September of which the monthly stem sap flow of L.sibirica;the order of stem sap flow velocity of B.pendula with diameter classⅠandⅣA.sibirica was that July>August>September>June;and The order of stem sap flow velocity the diameter classⅡwas that September>July>June>August;and the diameter classⅢwas that July>September>August>June.（4）In the growing season,there were no s pecific proportional relationship among the transpiration water consumption of all trees and their classes size.However,the consumption of transpiration water of the same species was obviously significant in different diameters.The consumption of transpiration water to the diameter classⅠand diameter classⅡof P.obovatas were 1997.06 g and 2873.09 g,and the diameter classⅠand diameter classⅡof P.sibirica were 1198.52 and5802.96 g.The L.sibirica was 3464.84 g,B.pendula was 2221.25 g.A nd from diameter classⅠto class diameterⅣof A.sibirica were respectively 705.08 g,1667.61 g,2919.18 g,and 6050.99 g.（5）On sunny day,the daily transpiration rate and photosynthetic rate of different diameters class A.sibirica’s leaves were consistent,and the order of transpiration rate of A.sibirica was that diameter classⅣ>diameter classⅡ>diameter classⅢ>diameter classⅠ.Meanwhile,its change of sunny side stem sap flow were consistent the shade side to the same tree.To the same tree,its change of sunny side transpiration rate and photosynthetic rate were consistent the shade side,but the transpiration rate of sunny side was 1.0².8 times to its shade side’s,and the photosynthetic rate of sunny side was 1.1⁴.3 times to its shade side’s.（6）The stem sap flow rate of all sample trees was highly significant positive correlation with temperature and photosynthetically active radiation（P<0.01）,but with air relative humidity was highly negative correlation（P<0.01）.It was also was highly significant negative correlation with water vapor pressure（P<0.01）,except the diameter classⅠP.obovata and the B.pendula.It was highly significant positive correlation with wind（P<0.01）,except the diameter classⅡP.obovata.The stem sap flow rate of diameter classⅠof P.obovatas,B.pendula and all diameter class A.sibirica were highly significant negative correlation with soil temperature（P<0.01）.And it highly negative correlation were with soil moisture（P<0.01）.Themaximum absolute value of soil temperature correlation with the stem sap flow rate of all sample trees was 0.421,and the maximum absolute value of soil moisture correlation with the stem sap flow rate of all sample trees was 0.215.（7）The transpiration rate of all diameter class A.sibirica were highly significant positive correlation with temperature and photosynthetically active radiation（P<0.01）,but with air relative humidity was highly negative correlation（P<0.01）.In addition toⅠdiameter class A.sibirica that was significant positive correlation with water vapor pressure（P<0.05）,the remaining diameter class trees were negative correlation with water vapor pressure（P>0.05）.And all trees were with wind were positive correlation（P>0.05）.The maximum absolute value of the correlation with the meteorological factors was 0.785.T he transpiration rate of all diameter class A.sibirica were negative correlation with different soil temperature levels（P>0.05）.The maximum absolute value of the correlation with the soil temperature factors was0.216,and with 0⁵cm soil moisture levels were highly negative correlation（P<0.01）,but with 5¹0 cm and 10²0 cm soil moisture were negative correlation（P>0.05）,and the maximum absolute value of the correlation with the soil moisture factors was 0.590.（8）For the stem sap flow was as independent variable,and for environmental factors was as dependent variable,doing multiple linear regression,and the result was significant（P=0.000）.For the deciduous tree species fitted better with environmental factors,they both had reached more than 0.6.To all trees,the B.pendula was the best,and evaluation value R2reached 0.810.The linear model was that Y=-2.951+0.735T-0.036AH-6.356VDP-0.158WS-2.752ST₅+8.202ST₁₀-13.462ST₂₀+0.22SP₁₀-0.789SP₂₀.To evergreen species,large diameter class trees simulated better than small diameter class trees.（9）The transpiration rate of all diameter class A.sibirica was highly significant positive correlation with photosynthetic rate and sap flow rate（P<0.01）.The maximum absolute value of all diameter class A.sibirica’s transpiration rate with the photosynthetic rate of all sample trees was 0.873,and the maximum with sap flowrate was 0.846.