油松、刺槐林潜在耗水量的预测及其与造林密度的关系

在大面积林分调查的基础上 ,构建边材生长模型和分布模型 ,并通过潜在液流通量Qp 预测模型完成了林分水平耗水在时间上的尺度放大 ,即预测林分的潜在耗水量Ep.结果表明 ,现存油松林地 (2 1年生 )潜在耗水能力Ep 大于刺槐林地 (9年生 ) ,10a后 (油松 31年生 ,刺槐 19年生 )二者接近 .若按相近龄级比较 (刺槐 19年生 ,油松 2 1年生 ) ,刺槐林地耗水能力大于油松林 .对不同造林密度的油松、刺槐林中短期耗水预测表明 ,在试验区的水文条件下 ,如果造林密度高于 15 0 0株 hm2 ,油松林一般都会在 2 0～ 30a内遭受水分胁迫问题而延缓生长 ,刺槐林则在 10～ 2 0a之内受到林地供水不足的胁迫 ;密度越高 ,水分供给不足问题出现越早 .通过实验分析 ,提出了 75 0株 hm2 的理论造林密度

Potential water use extrapolation and planting density calculation of Chinese pine and black locust stands in north Beijing mountain area.

Based on the sapwood growth models, potential sap flux density and scaling up theory of single tree to stand, the midterm and short term potential water use predictions of Chinese pine and black locust stands in different planting densities have been made. The short term and midterm predictions, which are called temporal scaling up, have also been accomplished by the establishment of sapwood growth models. It is predicted that, the present Chinese pine stand (21 years) has a relative large potential of water use than black locust stand (9 years); After 10 years (Chinese pine will be 31 years and black locust 19 years), they will get close. Under same age class (black locust is 19 years, Chinese pine stand is 21 years), black locust stand water use is much higher than Chinese pine stand. If the planting density exceed 1?500 plants/hm 2, the Chinese pine stands (under the hydrological conditions of the experimental area) will suffer from water stress in 20 to 30 years and black locust stands in 10 to 20 years. The higher the density, the earlier the water stress will occur. The appropriate plant density is 750 plants/hm 2 or a little greater when taking the survival rate in consideration.