Effects of sustained wind-sand flow on photosynthesis and transpiration rates of Pinus sylvestris var. mongolica saplings

To understand the effects of sustained wind-sand flow on the photosynthesis and transpiration rates of Pinus sylvestris var. mongolica saplings,a field wind-sand flow experiment with a gradient of wind speed treatments( 0 [CK],6,9,12,15,18 m / s) was conducted in the spring of 2013 in the Horqin Sand Land of Inner Mongolia. The results showed that:( 1) wind-sand flow over 9 m / s can significantly change daily photosynthesis rate patterns,( 2) wind-sand flow over12 m / s can significantly change daily patterns of stomatal conductance,( 3) wind-sand flow of 15 m / s and 18 m / s can significantly change the daily WUE pattern,and( 4) different strengths of wind-sand flows had a lesser effect on daily transpiration rates and intercellular CO2 concentrations compared to photosynthesis rate. Compared to the CK,the daily maximum and average photosynthetic rates increased by 12. 35% and 13. 8%,and 18. 33% and 38. 9%,at the 6 m / s and12 m / s treatments,respectively,and decreased by 17. 9% and 18. 9% at the 18 m / s treatments,respectively. The daily maximum and average transpiration rates increased by 51. 9% and 16. 9%,and 58. 6% and 53. 0%,at the 6 m / s and 15 m / s treatments,respectively,and decreased by 22. 5% and 18. 5% at the 18 m / s treatment,respectively. The daily maximum and average intercellular CO2 concentrations did not significantly differ with the 6-12 m / s treatments,ascompared to those in the CK,but increased by 86. 9% and 16. 5%,and 44. 5%,3. 28% with the 15 m / s and 18 m / s treatments,respectively. Compared to the CK,the daily maximum and average stomatal conductance increased by 14. 1%,26. 6%,and 27. 6%,45. 2%,at the 6 m / s and 15 m / s treatments,respectively,and decreased by 11. 95% and 13. 70%at the 18 m / s treatment,respectively. The daily average WUE increased by 7. 33%,1. 93%,18. 15%,3. 09% at 6,9,12,and 18 m / s respectively,and decreased by 13. 51% at 15 m / s.