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对美国佛罗里达州北部在砂质土上生长的树龄为3—36年生湿地松(Pinus elliott-ii)人工林进行两年时间枯落物及其分解作用的动态观察。15—35年生的五个林分,当林冠郁闭后,枯落物总数平均值为4993kg/ha·a,枯枝落叶量随林分年龄而增加,到15—16年达最高点,为4453kg/ha·a。以后便下降了。枯枝落叶最多时,针叶枯落物的氮和磷浓度最低,冬季枯枝落叶层最少,针叶枯落物的氮和磷浓度最高。在开头的18个月中,所有林分从落针分解消耗的有机物大致相同。在24个月时,便可明显看到受林分年龄影响的情况,老林分比幼年林分消耗有机物质慢。超过24个月,和其他森林类型的研究比较,有机物质消耗仍是缓慢的,其平均年腐率为15%。全林分鲜枯枝落叶的木质素比较高,而氮和磷跟其他林型枯落物比较则是低的,氮素在针叶中较稳定地保存24个月以上,而磷含量的增加超过最初数量的0—90%,表明林分较老针叶有较大量的磷累积。在这些营养缺乏的立地,其分解作用和矿化作用缓慢,可能归凶于湿地松人工林营造和相伴随的低强度燃烧次数减少的缘故。
Dynamic observation on the litter and its decomposition of Pinus elliott-ii plantation aged 3 to 36 years on sandy soil grown in the northern part of Florida, USA for two years. When the forest canopy was closed, the average number of litter was 4993kg / ha · a. The litter amount of litter increased with the age of forest and reached the highest point in 15-16 years 4453kg / ha · a. After the decline. When the litter was the most, the concentrations of nitrogen and phosphorus in the litter were the lowest, litters in winter were the least, and the concentrations of nitrogen and phosphorus in the litter were the highest. In the first 18 months, all of the stands consumed roughly the same amount of organic matter from the drop stitches. At 24 months, we can clearly see the impact of stand age. Older stand consumes slower organic matter than young stand. For more than 24 months, organic matter consumption is still slow compared to other forest type studies, with an average annual rate of 15%. The fresh lush leaves of the whole forest had higher lignin, while nitrogen and phosphorus were lower compared with other forest litters. Nitrogen was more stably stored in the needles for 24 months or more, while the phosphorus content increased More than the initial amount of 0-90%, indicating that the older trees needles have a larger amount of phosphorus accumulation. At these nutrient-deficient sites, their decomposition and mineralization are slow and may be attributable to the reduction in the number of low-intensity burns created and associated with Pinus elliottii plantations.