不同土壤水分条件下三个速生用材树种幼树的耗水特性比较

试验采用盆栽控水的方法,分析、比较了巨桉、竹柳和桤木3个速生用材树种幼树在3种水分条件下(土壤含水量分别保持在田间持水量的85%~80%、55%~50%、35%~30%)的耗水特性。结果表明:①相同天气和水分条件下,蒸腾速率、各时段耗水量、日耗水量和总耗水量绝大多数均表现为巨桉>竹柳>桤木;②相同处理下,巨桉与竹柳的日耗水速率并无显著差异(P>0.05),但都明显高于桤木;③巨桉明显较大的整株叶面积及其在水分亏缺时采取的不同避旱策略是其耗水量高于其它2个树种的重要原因;④树木的耗水能力是与其同化能力、生长速率密切相关的,随土壤含水量下降,各树种的净光合速率、叶面积、株高和地径生长量下降,蒸腾耗水也随之降低,但巨桉同化与耗水能力更不易受到干旱的影响;⑤巨桉和竹柳更适宜于在雨量充沛且季节分布均匀的地区发展,而在水分不足或季节性干旱频繁的地区则适合发展耗水量最小的桤木。

Comparison of Water Consumption Characteristics of Three Fast-growing Timber Species Sapling under Different Soil Water Conditions

A pot experiment with controlled water supply was performed to analyze and compare the water consumption characteristics of three fast-growing timber species (Eucalyptus grandis, bamboo willow (a hybrid of Salix) and Alnus cremastogyne under three soil water conditions (e.g., the soil water content was controlled at 85%－80%, 55%－50%, and 35%－30% field capacity, respectively). The results are as follows: 1) Under the same weather and soil water condition, the transpiration rate, interval water consumption, diurnal water consumption and total water consumption most presented the trend that E.grandis>bamboo willow>A.cremastogyne. 2) There was no significant difference between E.grandis and bamboo willow in terms of the diurnal water consumption rate (P>0.05), but both were obviously higher than A. cremastogyne. 3) Relatively larger total leaf area and the different drought avoid strategies were the main reasons for E.grandis consuming more water than the remaining two species. 4) The capacity of water consumption of a tree species was closely correlated to its assimilation ability and growth rate. No matter which species, the net photosynthetic rate, total leaf area, height and surface diameter increment all declined with the decrease of water consumption. However, compared with bamboo willow and A.cremastogyne, the assimilation and water consumption ability of E.grandis were more difficult to be affected by drought. 5) We came to the conclusion that E.grandis and bamboo willow are more suitable for the regions which have sufficient precipitation with even annual rainfall distribution, while A.cremastogyne is recommended to be planted in areas which often suffered water-deficient or seasonal drought.