基于树干液流通量的沙地樟子松合理林分密度的确定

应用热扩散式树干茎流计(TDP)对辽宁省章古台樟子松人工固沙林生长季期间树干液流速率进行了连续5年的测定,结合同步观测的降水、林冠截留量、林内蒸发散量和土壤水分含量,利用水量平衡的方法,推算了现阶段樟子松应有的合理密度。结果表明:4月上中旬沙地樟子松液流启动,10月中下旬液流基本结束,生长季(4-10月)各月平均液流速率分别为2.58、4.78、5.19、5.01、4.84、4.30、1.93 cm·h^-1,以6月份的最高,其次依次为7、8、5、9月份,4、10两月平均液流速率较低。通过推算,径阶14、16、18、20 cm的樟子松纯林的合理密度分别应为688、531、422、344株·hm^-2,现有同径阶的林分普遍存在密度过大的问题。研究结果对于现有林分的科学经营具有重要的指导意义。

Study on Proper Stand Density of Pinus sylvestris var. mongolica Plantation in Sandy Land Based on Stem Sap Flow Velocity

The precise determination of transpirational water-consumption is of great significance of the judgement of stand water balance. The present proper density of Pinus sylvestris var. mongolica plantation was calculated by means of water balance based on 5 years' observation of the precipitation, the canopy interception, the forest evapotranspiration, the soil water content and the sap flow velocity(SFV) which was measured by thermal dissipation probe(TDP) during the growing season. The sap flow observation of P. sylvestris var. mongolica in Zhanggutai started in early April and ended in late October, the monthly average SFV during the growing season from April to October were 2.58, 4.78, 5.19, 5.01, 4.84, 4.30 and 1.93 cm·per hour respectively, the highest SFV appeared in June, higher SFV appeared in July, August, May and September successively and lower SFV appeared in April and October. Through calculating, the proper density of P. sylvestris var. mongolica in 14, 16, 18, 20 cm diameter class were 688, 531, 422 and 344 plants per hectare. Over-high density was the common problem existed in pure stands in the same diameter class.