杨树超短轮伐期经营的生产力及材性的研究

THE BIOMASS PSODUCTIVITY AND WOOD QUALITY OF EASTERN COTTONWOOD IN MINIROTATION MANAGEMENT SYSTEMS

以美洲黑杨２个无性系为供试材料，研究杨树超短轮伐期经营中地上部分生物量生产、分配模式、Ｎ、Ｐ、Ｋ的输出量及材性。结果表明，在３种密度和３种轮伐期的组合中，２个无性系均以造林密度为１００００株·ｈａ－１、轮伐期为３年的林分生物生产力最高，Ｉ－６９杨为１０．５２ｔ·ｈａ－１·ａ－１，ＮＬ－８０３５１杨约为１２．００ｔ·ｈａ－１·ａ－１；在生物量的分配比率和作为造纸材的经济生物量上也以这种组合模式最为合理，经济生物量最大，Ｉ－６９杨为７．１４ｔ·ｈａ－１·ａ－１，ＮＬ－８０３５１杨为８·４７ｔ·ｈａ－１·ａ－１。养分输出量的多少与林分的生物量生产和分配比率密切相关。轮伐期为３年，密度为１００００株·ｈａ－１的林分Ｎ、Ｐ、Ｋ的输出量最高，Ｉ－６９杨为３３．９７ｋｇ·ｈａ－１·ａ－１，ＮＬ－８０３５１杨为３８．５０ｋｇ·ｈａ－１·ａ－１，但ＮＬ－８０３５１杨每生产１吨经济生物量所输出的Ｎ、Ｐ、Ｋ总量略低于Ｉ－６９杨。杨树超短轮伐期经营中生产出的木材都可用作中、低档的造纸原料，其中Ｉ－６９杨的制浆性能优于ＮＬ－８０３５１杨。

The above-ground biomass production, distribution model, nutrients exported and wood quality characteristics of eastern cottonwood were studied in minirotation management systems among the combinations of 3 densities and 3 rotations, The stand, with planting density of 10000 plant·ha-1 and 3 years rotation, could obtain the hightest biomass production 10. 52t·ha-1·a-1 for clone I-69 and about 12.00t. ha-1·a-1 for clone NL-80351. The economic biomass production for pulp-making was also the hightest in the stand of 10000 plant·ha-1 and 3-year-rotation, respectively 7.14t. ha·-1·a-1 for clone I-69 and 8. 47 t ·ha-1·a-1 for clone 8. 47t·ha-1·a-1. Nutrients exported from the minirotation management systems bear close correlation to the biomass production and distribution model. In the stand of 10000 plant·ha-1 and 3-year-rotation, the amount of nutrients exported (N,P and K) were 33. 97kg·ha-1·a-1 for clone I-69 and 38. 50kg·ha-1·a-1 for clone NL-80351. However,the amount of nutrients exported for producing one metric ton of economic biomass was slightly lower for clone NL-80351 than for clone I-69.The timber produced from the minirotation management systems is a good pulp-making material, but the wood quality of clone I-69 is slightly superior to clone NL-80351.