晋西黄土区主要造林树种单株耗水量研究

Water Consumption of Single-Tree from the Main Afforestation Species in Western Shanxi of Loess Area

依据水量平衡原理,采用桶栽试验分别测算晋西黄土区主要造林树种侧柏、刺槐、杏和河北梨生长季（4-10月）单株耗水量,并根据林地土壤水分动态及土壤水分特征曲线标定的各树种无效水界值,分析各树种土壤水分供耗特点及其有效性.结果表明：1）2002年（贫水年）生长季降水量430.7 mm,试验树种同期耗水量约为430～490 mm,供耗失衡;2003年（丰水年）降水量870.2 mm,耗水量约为480～515 mm,但降雨分配不均,5、10月供耗也略有失衡.2）不同树种年内土壤含水量变化趋势相近,而同月耗水量差异较大,同一树种不同月耗水量差异也较大,丰水年各试验地土壤水分状况要好于贫水年.3）侧柏、刺槐、杏和河北梨无效水界值分别为8.0%、8.4%、9.2%和9.7%,侧柏较其他3个树种利用水分能力强;贫水年林外单株树木土壤含水量在一段时间内低于对应树种的无效水界值,影响树木正常生长;单株树木依靠冬季和次年春季降水补充,生长季初期都能恢复到速效水水平.

Water is the key factor to vegetation growing in Loess area. Therefore, researchers are keen on the study of tree transpiration for a long time. In order to provide the scientific basis and practical instruction for the vegetation reconstruction and recovery in Loess area, the paper measured and calculated water consumption of potted Platycladus orientalis, Robinia pseudoacacia, Armeniaca vulgaris and Pyrus hopeiensis separately during the growing season （from Apr. to Oct. ）, which were the main afforestation species in western Shanxi of Loess area, based on the principle of water balance. Besides, according to the data of soil water dynamic and the range of available moisture of potted mature trees, the relationship between water supply and consumption and the soil moisture availability and deficit state were analyzed. Several conclusions are listed as follows： 1） In the dry year （2002）, during the growing season the precipitation was 430.7 mm and the water consumption of potted trees was from 430 mm to 490 mm. More water consumption and less available water supply occurred, showing a serious water deficiency. In the rainfall-rich year （2003）, during the growing season the precipitation was 870.2 mm and the water consumption of potted trees was from 480 mm to 515 mm. Due to uneven distribution of rainfall, the water budget lost balance a bit in May and Nov. 2） The curves of soil water content of different species had similar change trends in annual but different in the same month, and those of thesame tree species in different test plots had different change trends in the same month either. 3） Non-available soil water content of P. orientalis, R. pseudoacacia, A. vulgaris and P. hopeiensis was less than 8.0%, 8.4% , 9.2% and 9.7% respectively, which indicated that P. orientalis used water more efficiently than others. In the deficit water year （2002）, for several months, soil water content of potted trees was lower than its non-available soil water content, which could influence trees healthy growing, After supplements of precipitation of winter in the year and spring in the next year, soil water contents were higher than the lower limit of soil readily available moisture content, which implied that interannual water supply and consumption could keep balance.