树木年轮生长释放一直广泛应用于重建森林干扰, 但没有直接的研究证明利用树木年轮分析建立的干扰强度的可靠程度, 本文试图通过一个取自青海省互助国家森林公园( 1987 年经历过择伐) 的样方进行验证。在 40m ×50m 的青扦( Picea wilsonii Mast.) 林样方内取胸径≥5 cm 的树木( 124 株) 树轮芯样并测定胸径、 树高和择伐后山杨( Populus daviliana Dode) 树桩( 55 个) 的基径以及树木与树桩的距离。分析结果表明:1987 和 1988 年树木生长释放百分率为 38.7 %, 与该林分的准确干扰强度 37 .7%( 树桩基部断面积与该断面积加树木胸高断面积之和的比值)相接近。1980～ 1989 年 10 a 间树木生长释放百分率为 62.9 %, 该 10 a 间的平均干扰强度为 37.0 %( 生长释放百分率 62.9% 生长释放平均次数 1.7) , 也接近于该林分的准确干扰强度, 因而用树轮资料重建森林干扰强度是可行和可靠的。
 

Based on the investigation of 33 plots in Jing County and Qingyang County, the effects of management practice on above-ground biomass and phloem yields were analysed. The results indicated that: ( 1) In the Pteroceltis tatarinowii Maxim. plantations with same density and same stump age, pholem production ( kg hm2 ) increased, but the rate of phloem to above-ground biomass ( % ) decreased with the increasing of sprout age. ( 2) For the sprouts with different age, the highest annual increment of phloem to above-ground biomass occurred in the third year, which is 1. 58 times of the second year, 4. 12 times of the fourth year. ( 3) In the same density but different stump age, the phloem production ( kg hm2 ) of P. tatarinowii plantations increased with the increasing of stump age and the highest productivity of phloem occurred in the stands with 12-year-old stump, which is 3. 32 times of the stand with the 6-year-old stump, and 1. 11 times that of the 9-year-old stump . ( 4) Within four planting densities ( 2 500, 3 333, 4 200 and 5 350 stumps hm2) , the highest production of phloem took place in the stand with 4200 stumps hm2, reaching 3 765 kg hm2, which is 1. 68 times of the stand with 2 500 stumps hm2 . The ranking of phloem production was in the order 4200>3 333>5 350>2 500 stumps hm2 . ( 5) In the stands with 3 333 stumps hm2 and 9year-old stump, the highest production of phloem was achieved in the stand with 10 sprouts on each stumps. On the basis of the results, we suggest that 3 333～ 4200 stumps hm² should be chosen as a planting density, 3 years should be chosen as a harvesting cycle and 10 sprouts on each stump should be an option for the stands with over 9-year-old stumps in the practice so that high phloem production can be obtained.