摘要
本文以北京市官厅库区水源涵养林的主要造林树种：小叶杨、刺槐为研究对象，采用当前国内外最先进的热脉冲式树干边材液流测定技术和热扩散式树干边材液流测定探针(TDP)测定技术，从叶片和单株水平上探讨了刺槐和小叶杨的蒸腾耗水特性以及它们与环境因子之间的影响机理，其结果不仅可为更精确地估计生态用水定额提供科学依据，而且也可为该区域这两种树种的选择及其合理林分的密度起到一定的指导作用。该研究的主要结论如下：
1)研究了小叶杨和刺槐树种的叶片蒸腾耗水规律：叶片蒸腾速率随着辐射强度的增强而增强，08：00，小叶杨叶片蒸腾速率为77.66g／m~2·h，而刺槐仅为20.98g／m~2·h；大约在12：00-15：00达到峰值，小叶杨和刺槐分别为229.73g／m~2·h和143.94g／m~2·h。之后又逐渐减小。在本试验条件下，对于小叶杨，辐射强度和空气温度日变化对叶片蒸腾速率日变化的影响较为显著，10cm土壤温度、相对湿度和风速对叶片蒸腾速率日变化的影响不明显：而对于刺槐，其叶片蒸腾速率与太阳辐射相关性较好，与空气温度、空气湿度、土壤温度和风速日变化与叶片蒸腾速率之间无显著性相关。
2)研究了小叶杨和刺槐树种的树干边材液流的日变化、连日变化以及月变化进程，发现小叶杨和刺槐树干液流日进程均呈现出明显的昼夜变化规律，通常白天07：00～08：00液流开始上升，以后，随着辐射强度的增强，气温、土壤温度的增加，使得液流速率不断上升，并且在12：00～15：00左右达到其峰值，然后开始下降，19：00左右速度变慢，直至来日日出之前达到最低值；也证明夜间有微弱液流存在，这是树体水分恢复和储水阶段，以备来日耗水之用。
3)研究了边材液流随方位、插入位点和径阶的变化规律，探明在树干的不同方位，液流速率存在有一定差异，规律为：西侧＞北侧＞南侧＞东侧；树干不同位点的液流速率在昼夜变化趋势及峰形一致，但其峰值存在有一定差异，整个树干径向不同位点的液流速率由外向内呈下降趋势；边材液流速率随径阶的增大无明显规律，但液流通量和耗水量随径阶的增大而增大。
4)通过对树干边材液流规律的测定发现，刺槐的边材率较低，只有14.8％，而小叶杨边材率为81.8％。
5)本文分析了不同气象因子对液流的影响方式，建立了两树种边材液流速率与微气象因子的多元线性模型，并表现出良好的相关性(小叶杨：Vs＝9.467—0.109RH+0.322Ta+4.108×10~(-3)ESR—0.268Ts，R~2=0.963；刺槐：Vs=6.033×10~(-3)ESR+0.749Ta—9.502，R~2=0.956)。
6)以小叶杨树种为例，利用其边材宽度与胸径之间良好的相关性(Ysy=2.87+0.23×Xsy，R~2=0.97)，在热扩散技术测定的单株耗水量的基础上，完成了单株耗水到林分耗水的空间尺度放大。
The two tree water consumption characteristics, Populus simonii and Robinia pseudoacacie, and the interactions mechanism with environment factors were both studied at the level of leaf and singletree in terms of the modern technology of heat pulse sap flow and thermal dissipation sap flow probe (TDP). The two main purposes of study are to provide the science evidence in estimating the ecologic water consumption rules and to arrange better densities of the two tree species stand. The main suggestions are showed as below.
1) It shows that the leaf transpiration rates of the two tree species increased with the radiation and they, for example, were 77.66g/m2 . h for Populus simonii and 20.98g/m2 . h for Robinia pseudoacacie at 8:00, but were 229.73g/m2 . h for Populus simonii and 143.94g/m2 . h for Robinia pseudoacacie at 12:00 ~ 15:00, which were the peak points of the two tree species respectively. Then, the transpiration rates decreased smoothly. The transpiration rates of reaction to environment factors of the two tree species were different in the condition, which the radiation, air temperature had significantly effect on Populus simonii, but the soil temperature in 10cm, relative humidity and wind speed had little effect on it. For Robinia pseudoacacie, on the other hand, the leaf transpiration velocity was well relative with solar radiation, but there were not significant different between the leaf transpiration velocity and the air temperature, relative humidity, soil temperature and wind speed.
2) The normal rules of sap flow of the two tree species from day to night were that it began from 7:00-8:00, and increased smoothly with the strength adding of solar radiation, air temperature and soil temperature. When it reached peak at 12:00-15:00, the value became to decrease gradually. At 19:00, it decreased more slowly, but till daybreak, it get the minimum point. The interest phenomena found was that there was sap flow in nighttime, although it was faintly, which would be stem water restoration and storage for day transpiration.
3) It is demonstrated the sap flow values probed in the stem were varieties in different directions. The value sequence was westward > northward > southward > eastward. At different directions of the stem, the change rules of sap flow rates, from daytime to nighttime, were the similarity, but the only different point was the value of peak. From transect of stem, the sap flow rates decreased gradually from sapwood to duramen. Also, there was not distinct regulation between the sap flow velocity and the diameter, but the
sap flux density and the water consumption were increasing with tree diameter.
4) According to the measurement on sap flow of the two tree species, the sapwood of Robiniapseudoacacie was smaller than Populus simonii, which were 14.8% and 81.8%.
5) Based on the analysis, the multi-linearity models of the two tree species were built between sap flow rate and micrometeorological factors, which showed a significant correlation (Populus simonii: Vs = 9.467 - 0.109RH+0.322Ta + 4.108 X 10 ~ 3ESR -0.268Ts, R2=0.963; Robinia pseudoacacie: Vs=6.033 X 10-3ESR+0.749Ta- 9.502, R2= 0.956)
6) With the Populus simonii as example, the significant correlation between the sapwood width and tree diameter (Ysy=2.87+0.23 XXsy, R2=0.97), the stand water consumption models were successfully established from singletree water consumption monitored by thermal dissipation technology.
引文
[1]赵松桥．中国的干旱区[M]．北京：科学出版社，1990．
[2]王礼先．植被生态建设与生态用水—以西北地区为例[J]．水土保持研究，2000，7(3)：5～7．
[3]周晓峰．关于西部大开发的基本观点和植被建设中的若干问题[J]．林业科学，2001，37(6)：98～104．
[4]候庆春，韩蕊莲．黄土高原植被建设中的有关问题[J]．水土保持通报，2000，20(2)：53～56．
[5]梁一民．从植物群落学原理谈黄土高原植被建造的几个问题[J]．西北植物学报，1999，19(5)：26～31．
[6]杨光，王玉．试论植被恢复生态学的理论基础及其在黄土高原植被重建中的指导作用[J]．水土保持研究，2000，7(2)：133～135．
[7]中国可持续发展林业战略研究项目组．中国可持续发展林业战略研究总论[R]．北京：中国林业出版社，2002．
[8]孙鹏森．京北水源保护林树种不同尺度耗水特性及林分配置的研究[D]．北京林业大学博士论文，2000．
[9]Marshall D C. Measurement of sap flow in conifers by heat transport. Plant Phusiology, 1958, 33:385～396.
[10]Swanson R H, Whittled D W A. A numerical and experimental analysis of implanted probe heat polse theory. J Exp Bot, 32.. 221～239.
[11]Leyton L. Physiology of tree crops(L G Luckwill and C V Cutting, eds. )Proc, symp. held at long AshtonRes[J]. Stn, Univ. Bristol, March, 1969, Academic Press, NwYork. pp. 382.
[12]刘奉觉，Edwards W RN，郑世锴等．杨树树干液流时空动态研究[J]．林业科学研究，1993，6(4)：368～372．
[13]李海涛，陈灵芝．应用热脉冲技术对棘皮桦和五角枫树干液流的研究[J]．北京林业大学学报，1998，20(1)：1～6．
[14]高岩，张汝民，刘静．应用热脉冲技术对小美旱杨树干液流的研究[J]．西北植物学报，2001，21(4)：644～649．
[15]高岩，刘静，张汝民等．应用热脉冲技术对小美早杨耗水量的研究[J]．内蒙古农业大学学报，2001，22(1)：44～48．
[16]马李一，孙鹏森，马履一．油松刺槐单木与与林分水平耗水量的尺度转换[J]．北京林业大学学报，2001，23(4)：1～5．
[17]熊伟，王彦辉，徐德应等．宁南山区华北落叶松人工林蒸腾耗水规律及其对环境因子的相应
[J]．林业科学，2003，39(2)：1～7．
[18]Granier A, R Huc&S T Barigah. Transpiration of natural raingorest Meteorology[J]. 1996, 78:19～29.
[19]王华田，马履一，孙鹏森．油松、侧柏深秋边材木质部液流变化规律的研究[J]．林业科学，2002，38(5)：31～37．
[20]王华田，马履一．利用热扩式边材液流探针(TDP)测定树木整株蒸腾耗水量的研究[J]．植物生态学报，2002，26(6)：661～667．
[21]马履一，王华田．油松边材液流时空变化及其影响因子研究[J]．北京林业大学学报：2002，24(3)：23～27．
[22]孙慧珍，周晓峰，赵惠勋．白桦树干液流的动态研究[J]．生态学报，2002，22(9)：1387～1391．
[23]虞沐奎，姜志林，鲁小珍等．火炬松树干液流的研究[J]．南京林业大学学报，2003，27(3)：7～10．
[24]Francno C M, Magalhaes A C. Techniques for the measurement of transpiration of individual plants[J]. Arid Zone Res, 1965, 25: 211～224.
[25]刘奉觉，郑世锴，藏道群．杨树人工幼林的蒸腾变异与蒸腾耗水量估算方法的研究[J]．林业科学，1987，23(营林专集)：35～44．
[26]王孟本，李洪建．柠条林蒸腾状况与土壤水分动态研究．水土保持通报，1990，lO(6)：85～90．
[27]刘增文，王佑民．人工油松林蒸腾耗水及林地水分动态特征的研究[J]．水土保持通报，1990，10(6)：78～84．
[28]王孟本，李洪建．柠条林蒸腾与土壤水分动态研究[J]．水土保持通报，1990，10(6)：85～90．
[29]李洪建，王孟本，陈良富等。刺槐林分生态研究[J]．植物生态学报，1996，20(2)：151～158．
[30]李洪建，王孟本，柴宝峰．晋西北人工林土壤水分特点与降水关系研究[J]．土壤侵蚀与水土保持学报，1998，4(4)：60～65
[31]刘奉觉．快速称重法蒸腾测值的订正[J]．杨树水分生理研究，北京：林业出版社，1992，p35～40．
[32]王华田．林木耗水性研究述评[J]．世界林业研究，2003，16(2)：23～27．
[33]Hinckley T M,J R Books,et al,water flux in a hybrid poplar stand[J].Tree Physiol,1994,14:1005～1018.
[34]Meinzer F C G, Goldstein P, Jackson N M, et al. Environmental and physiological regulation of transpiration in tropical forest gap species: the influence of boundary layer and hydraulic properties[J], Oecologia 1995, 101: 514～522.
[35]Landsberg J J, T W Blanchard, B Warrit. Studies on the movement of water through apple trees[J]. J. Exp. Bot. 1976, 27: 579～596.
[36]Schulze E D, J Eermak, R Matyssek, M Penka, et al. Canopy transpiration and water fluxes in the xylem of the trunk of Larix and Picea trees a comparison of xylem flow, porometer and cuvette measurements[J]. Oecologia, 1985, 66: 475～483.
[37]Cochard H, N Breda, A Granier. Whole tree hydraulic conductance and water loss regulation in Quercus during drought: evidence for stomatal control of embolism?Ann[J]. Sci. For. 1996, 53:197～206.
[38]Aston M J, D W Lawlor. The relationship between transpiration, root water uptake, and leaf water potential[J]. J. Exp. Bot. 1979, 30: 169～181.
[39]Kuppers M. Carbon relations and competition between woody species in a Central European hedgerow. Ⅱ. Stomatal responses, water use, and hydraulic conductivity in the root/leaf pathway. Oecologia, 1984, 64: 344～54.
[40]Meinzer F C, M R Sharifi, E T Nilsen, et al. Effects of manipulation if water and nitrogen regime on the water relations of the desert shrub Larrea tridentate[J]. Oecologia, 1988, 77: 480～486.
[41]Reich P B, T M Hinckley. Influence of predawn water potential and soil-to-leaf hydraulic conductance on maximum daily leaf diffusize conductance in two oak species[J]. Funct. Ecol, 1989,3: 719～726.
[42]Meinzer F F, D A Grantz. Stomatal and hydraulic conductance in growing sugarcane: stomatal adjustment to water transport capacity[J]. Plant Cell Environ, 1990, 13: 383～388.
[43]Sperry J S, W T Pockman. Limitation of transpiration by hydraulic conductance on stomatal conductance and xylem cavitation in Betula occidentalis[J]. Plant Cell Environ, 1993, 16: 279～287.
[44]Meinzer F C, G Goldstein, P Jackson, et al. Environmental and physiological regulation of transpiration in tropical forest gap species: the influence of boundary layer and hydraulic properties[J]. Oecologia, 1995, 101: 514～522.
[45]Schulze E D, J Eermak, R Matyssek, et al. Canopy transpiration and water fluxes in the xylem of the trunk of Larix and Picea trees a comparison of xylem flow, porometer and cuvette measurements[J]. Oecologia, 1985, 66: 475～483.
[46]Lousrau D, P Berbigier P, et al. Transpiration of a 64-year-old maritime pine stand in Portugal. 1. Seasonal course of water flux through maritime pine[J]. Oecologia 1996, 107: 33～42.
[47]Schiller G,Y Clhen. Water regime of a pine forest under a Mediterranean climate[J]. Agric. For. Meteorol. 1995, 74: 181～193.
[48]Lousrau D, P Berbigier, P, et al. Transpira～tion of a 64～year～old maritime pine stand in Portugal. 1. Seasonal course of water flux through maritime pine[J]. Oecologia, 1996, 107: 33～42.
[49]Barrett D J, T J Hatton, J E Ash, et al. Transpira～tion by trees from contrasting forest types[J]. Aust. J. Bot. 1996, 44: 249～263.
[50]Roberts J. The use of tree-cutting techniques in the study of the water relations of pinus sylvestris[J]. L. J. Exp. Bot, 1977, 28: 751～767.
[51]Knight, H H, T J Fahey, S W Running, etal. Transpiration from 100-year-old lodgepole pine forests estimated with whole-tree potometers[J]. 1981, Ecology 62:717～726.
[52]Swanson R H. Significant historical developments in thermal methods for measuring sap flow in trees[J]. Agric. For. Meteorol, 1994, 72: 113～132.
[53]Smith, D M, S J Allen. Measuremeat of sap flow in stems[J]. J. Exp. Bot. 1996, 47: 1833～1844.
[54]Waring, R H. J M Roberts. Estimating water flux through stems of Scot pine with tritated water and phosphous～32[J]. J. Exp. Bot. 1979, 30: 459～471.
[55]Dye, P J, B W Olbrich, I R Calder. A comparison of heat pulse method and deuterium tracing method for measuring transpiration from Eucalyptus grandis trees[J]. J. Exp. Bot. 1992, 43: 337～343.
[56]Greenwood, E A N, J D Beresfored. Evaoration from vegetation in landscape developing secondnary salinity using the ventilated～chamber technique I comparative transpiration from juvenile Eucalyptus above saline ground-water seeps[J]. J. Hydrol. 1979, 42: 369～382.
[57]Dunin, E X, E A N Greenwood. Evaluation of the ventilated chamber technique for measuring evaporation fromaforest[J]. Hydro. Proc. 1986, 1: 47～62.
[58]Fritschen, L J, L Cox, R Kinerson. A 28～meters Douglas～fir in a weighing lysimeter[J]. For. Sci,1973, 19: 256～261.
[59]Edwards W R N. Precision weighing lysimeter for trees, using a simplified tared～balance design[J]. Tree physiol. 1986, 1: 127～141.
[60]刘奉觉，郑世锴，巨关升．树木蒸腾耗水测算技术的比较研究[J]．林业科学，1997，33(2)：117～126．
[61]Roberts J M. The use of"tree cutting " techniques in the study of the water relations of mature Pinus sylvestris L 1. The technique and survey of the results[J]. JExp Bot, 1977, 28:751～762
[62]Lindroth A E Cienciala. Measuring water use efficiency of eucalypt trees with chambers and micrometeorological techniques comment[J]. J. Hydrol. 1995, 169: 281～283.
[63]Zimmerman M H. Xylem structure and the ascent of sap. Springer～Verlag Berlin Heidelberg New York Tokyo[D]. 1983, pp. 26.
[64]李银芳，杨戈，蒋进．不同灌水处理六个树种蒸腾速率与气象因素的关联分析[J]．干旱区研究，1994，11(4)：30～32．
[65]刘淑明，孙丙寅，孙长忠．油松蒸腾速率与环境因子关系的研究[J]．西北林学院学报，1999，14(4)：27～30．
[66]殷祚云，胡玉佳，陈建新等．马尾松针叶蒸腾强度日变化与小气候的关系[J]．仲恺农业技术学院学报，1999，12(3)：15～18．
[67]王华田．北京市水源保护林区主要树种耗水性研究[D]．北京林业大学，2002．
[68]Swanson R H. Seasonal course of transpiration of lodge pole pine and Engelmann spruce. In: W E Sopper and H. W.Lull(Editors), International Symposium on Forest Hydrology[D]. Pergamon, London, 1967, pp. 419～434.
[69]刘发民．利用校准的热脉冲方法测定松树树干液流[J]．甘肃农业大学学报，1996，31(2)：167～170．
[70]王沙生，高荣孚，植物生理学[M]，中国林业出版社，1990．
[71]贺庆棠．植物生理学[M]．农业出版社，1981．
[72]高清泽．植物生理学[M]．华罔出版有限公司印行．
[73]孙鹏森，马履一．油松树干液流的时空变异性研究[J]．北京林业大学学报，2000，22(5)：1～5．