柠条主根液流与叶面积关系初探

运用热扩散技术对3株柠条主根部液流速率进行了监测,对试验期间典型晴天日(30d)液流速率的分析表明:柠条根部液流传输受大气蒸发力、冠层输出、边材面积的共同影响;1、2、3号样株边材面积分别为6.61、7.17、5.06 cm2,日平均液流总量分别为457.92、1014.66、292.12 g·d-1,日平均液流总量随边材面积的增加而增大;各样株间日平均液流总量的差异显著,而单位叶面积的液流量无显著差异;2号柠条样株的液流速率日变化动态与潜在蒸发散的相关性最强,叶面积/边材面积为0.62m2·cm-2,可以作为评定柠条单株是否具有与当地水文条件相适应的根冠比例关系的重要指标.试验期间样株根区60～140 cm内土壤平均含水量分别占田间持水量的51.04%、63.26%和87.0%,土壤水分状况较好.

Preliminary Study on Relationship between Taproot Sap Flow andLeafArea of Caragana korshinskii

Based on samp ling and measuring sap flow in taproo t of Caragana korsh inskii by Therma l D issipationProbe( TDP), data fo r 30 typ ica l sunny days w ere se lected for ana lyzing, it show ed that the transportat ion o f sapflow in taprootw as contro lled by atmosphere evaporat ion, canopy export and sapw ood area. Sapwood area played animportant ro le in ensuring w ater transport unblocked under high atmosphere evaporating and canopy transportingcond it ion. Itw as indica ted that the da ilymean sap flow velocity ofNo. 1 3 samp le treesw ere 457. 92, 1 014. 66 and292. 12 g?d^-1 respect ive ly, and the sapw ood areaw ere 6. 61, 7. 17, and 5. 06 cm² respectively, the form er variedaccording ly w ith the latter. Therew ere sign ificant d ifferences in sap flow velocity among the sample trees, wh ile nosign ificant d ifferences w ere found in sap flow velocity per leaf area, so leaf areawh ich characterized by canopy tran spiration dem andsmay be amore importan t variable than sapw ood area forw ater transport ing and so ilw ater fo r pro v id ing in soil p lant atmosphere con tinuum. The so ilmo isture cond it ion at depth from 60 to 140 cm in trial periodw as adapted for 3 sample trees o fCaragana korshinsk ii, wh ich accoun ted fo r 51. 04%, 63. 26% and 87. 0% of f ie ldmoisture capacity respectively. The daily variat ion pattern o f No. 2 w as related w ith Poten tial Evapotransp iration( ET0 ) more c lose ly than the o thers, so the ratio o f leaf area to sapwood area of No. 2 wh ich w as 0. 62m²? cm^-2imp lied that the ab ility of sapwood transportationmatched w e llw ith canopy demands, and could be used as a b io log ical characteristic index for reflecting the hydro log ical adaptat ion ofCaragana korshinskii.