尾巨桉与杉木、香樟耗水特征分析

在广西黄冕林场采用Granier热扩散技术方法对人工纯林桉树、杉木和香樟的液流密度、液流通量、单株日均耗水量及耗水量与主要环境因子的关系进行了研究.结果表明:3个树种树干液流密度均与光合有效辐射有一致的变化规律和单峰曲线.综合分析显示桉树在3个树种中耗水能力最强,虽然香樟液流密度比杉木大,但因为边材面积最小,所以表现出耗水量最小,单株日均耗水量仅有桉树的0.5倍左右,而杉木虽然边材面积比桉树大,但耗水量并不高,仅为桉树的0.7倍左右;通过偏相关分析发现3个树种的液流通量均与光合有效辐射、水气压亏缺和空气温度有极显著的正相关关系,杉木和香樟液流通量与空气相对湿度有极显著的负相关关系,而桉树表现不显著;通过多元线性分析发现3个树种的液流通量均与光合有效辐射、空气温度和空气相对湿度有很强的线性相关关系.3个不同树种的耗水研究结果可为本地区造林树种选择的优劣性提供参考.

Analyses on Water Consumption Characteristics of Eucalyptus urophylla ×E. grandis,Cunninghamialanceolata and Cinnamomuncamphora

The sap flow densities of Eucalyptus urophylla×E. grandis, Cunninghamia lanceolata and Cinnamomun camphora plantations were measured over a period of five days using the Granier thermal dissipation probe method in the Guangxi Huang-mian Forest Farm. The sap flow flux, average daily water consumption and the relationship between the sap flow density and the main environmental factors were analyzed. Sap flow density of the three tree species coincided with the photosynthetically active radiation following a singleton curve pattern. Further analyses showed that E.urophylla×E.grandishad the strongest water consumption of the species. Although sap flow density of C. camphora was larger than that of C. lanceolata, its overall water consumption was the lowest as it had the smallest sapwood area and this resulted in its daily water consumption per tree being only 0.5 times that of C. camphora.For the latter, whilst its sapwood area was larger than that of E.urophylla×E.grandis, its water consumption amounted to only about 0.7 times of E.urophylla×E.grandis. All three species showed similar trends in water consumption in relation to photosynthetic active radiation (PAR), with water use in all three following unimodal curves. By partial correlation analyses it was found that the sap flow rates of the three species were related to photosynthetic active radiation, water pressure deficit; and, whilst there was a significant positive correlation between the flow ratesin C.camphora and C.lanceolata and relative air humidity, the same correlation for E.urophylla×E.grandis was not significant. The results of this sap flow and water consumption study on the three different tree species can provide a valuable reference for the selection of afforestation tree species in the region.