Studies On Water Consumption Model Of Main Tree Species Of Afforestation In Loess Plateau

The Loess Plateau in our country is of a vulnerable ecological balance.The local eco-environment building directly affected people's living and production.Everyone knows that trees growing couldn't with out water,so if you have more knowledge about the saplings' evapotranspiration pattern in earily times .It is important to increase the success ratio of afforestation,water use efficiency in practice.The dissertation chose the main afforestation tree species Patycladus orientalis, Larixprinapiam-rupprechtii,Pinutabulaeformis,Populusbolleana,Ailanthusaltissima,Zizyph us jujube, Ulmus pumila and Juglans regia on Loess Plateaus in Growing Seasons of 2006, july. We have their transpiration rate and other factors with Li-1600 Steady State Porometer in seedling growth period. In the meantime, the samples' weight were measured with SR64000 precision balance and we used the weighing methord to get the soil moisture, HOBO automatic weather station was applied as well.Then screen out the right data ,wo used the matlab software to do the principal components analysis .The result is we get the main factors of each tree,and simulate the modle of evapotranspiration and key factors. Main research results are as follows:Through the principal components analysis we know that the influenced factors of evapotranspiration are leaf water potential, transpiration rate, soil water content, stomatal conductance, radiant intensity, leaf tempreture, air relative humidity.In one day,the decreasing orders of average transpiration rate of the eight tree species were Populus bolleana,Ailanthus altissima, Larix prinapiam-rupprechtii, Patycladus orientalis,Ulmus pumila,Pinus tabulaeformis, Juglans regia,Zizyphus jujube.but the decreasing orders of average daily evapotranspiration were Populus bolleana, Patycladus orientalis, Ailanthus altissima, Larix prinapiam-rupprechtii, Pinus tabulaeformis, Juglans regia, Zizyphus jujube, Ulmus pumila.From thouse two orders we can see that the average transpiration rate and the average daily evapotranspiration of the eight tree species don't consistent,when the former is high ,but the later maybe very low,just so so.The paper believes that the Populus bolleana and the Ailanthusaltissima consume more water than other species,so when choose them to afforestation,we suggest planting them in shady slope or channel whose soil water content is higher;when plant the lower water consumption tree species just as Patycladus orientalis, Larix prinapiam-rupprechtii and Pinus tabulaeformis, we suggest planting them in the lower soil water content place,for example, sunny slope and the top of loess hill;the Ulmus pumila, Zizyphus jujube and Juglans regia don't consume lots of water and have economic benefit to local people,so they are precede to other tree species. The modles of evapotranspiration and major influence factors of different tree species:The modle of Patycladus orientalis is: ET = -22. 65Gs-10. 49RH+2420. 401W+953. 37;The modle of Larix prinapiam-rupprechtii is: ET = -100. 48Tr-20. 76LT+7600. 23W+246. 80;The modle of Pinus tabulaeformis is: ET = 1. 78Gs+0. 73PAR-1. 66LT+296. 50W+98. 98;The modle of Populus bolleana is: ET = 974. 59W+17. 47Gs+0. 21PAR-35. 48Tr+498. 07;The modle of Ailanthus altissima is: ET = -2. 76LT +3. 52Gs-192. 44W+19. 34Tr+218. 19;The modle of Juglans regia is: ET = 685. 81W-2. 43LT+21. 38Tr+222. 81;The modle ofZizyphus jujube is: ET = 460. 26 Ψ+20. 65Tr-0. 39PAR-51. 21LT+3002. 59;The modle of Ulmus-pumilais: ET = 950. 23 Ψ+4. 00Gs+10. 72Tr+0. 53PAR+979. 30.