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131.
132.
美国黄松与秦岭主要松属种叶燃烧性比较 总被引:4,自引:0,他引:4
测定了美国黄松及秦岭松属4种2龄针叶的6个燃烧性因子,并用层次分析的两两比较法分析认为,美国黄松针叶燃烧性差,油松、黑松、白皮松叶燃烧性较强。 相似文献
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134.
1998年4月至1999年3月对广州市白云山马尾松林和常绿阔叶林、广州市龙眼洞马尾松林两试验点进行了酸雨的监测,并测定和分析了林内穿透雨物理量及化学量,旨在探讨酸雨对不同森林冠层养分淋溶规律的影响。结果表明:(1)广州市酸雨占次数的79.7%或占降雨量的95.1%。(2)酸雨通过林冠层后,pH值明显增加。(3)在马尾松林和常绿阔叶林中,某些单次降雨出现SO4^2-、NO3^-、NH4^+Al^3+、Na^+的负淋溶现象,说明森林对这些离子(特别是NO3^-、Aa^3+)具有吸收作用;阔叶林全年的NO3^-和Al^3+净淋溶为负值,说明阔叶林比马尾松林对这两种离子具有更强的吸收能力。(4)雨水酸度增加(即pH值减小),明显提高阳离子Ca^2+、Mg^2+、K^+和Na^+冠层淋溶面分率。(5)NH4^+、SO4^ 相似文献
135.
The biomass and the spatial distribution of fine and small roots were studied in two Japanese black pine (Pinus thunbergii Parl.) stands growing on a sandy soil. More biomass of fine and small roots was found in the 17-year-old than in the 40-year-old
stand. There were 62 g m−2 of fine roots and 56 g m−2 of small roots in the older stand, which represented mean values of 608 g for fine and 552 g for small roots per tree, respectively.
In the younger stand, a total of 85 g m−2 of fine roots and 66 g m−2 of small roots were determined, representing a mean of 238 g for fine and 186 g for small roots per tree, respectively. Fine
and small root biomasses decreased linearly with a soil depth of 0–50 cm in the older stand. In the younger stand, the fine
and small roots developed only up to a depth of 30 cm. Horizontal distributions (with regard to distance from a tree) of both
root groups were homogeneous. A positive correlation in the amount of biomass of fine and small roots per m2 relative to tree size was found. Fine and small root biomasses increased consistently from April to July in both stands.
The results also indicated earlier growth activity of the fine roots than small roots at the beginning of the growing season.
The seasonal increases in fine and small root biomasses were slightly higher in the younger stand than the older stand. 相似文献
136.
Measurements were carried out to survey the quantity of above- and below-ground biomass and its distribution of five Japanese
black pines (Pinus thunbergii Parl.) growing on a sandy soil. The roots, divided into diameter groups, were surveyed using two methods—soil coring and
excavation. Average dry weight of total biomass of the trees was 176,185 g. Roots represented 13.2%, below-ground stump 6.5%,
stem 70.4% and branches with needles 9.9% of total biomass. Roots made up about two thirds and stump one third of below-ground
biomass. Total length of below-ground biomass (except roots with diameter < 0.1 cm) was 479.1 m/tree. Roots with diameter
of 0.1–0.2 cm represented only 0.7% of below-ground biomass, however as much as 49.9% of their total length. Roots with diameter
over 10.0 cm constituted as much as 21.6% of below-ground biomass, however were only 0.3% of its total length. Root systems
had well developed tap roots to maximal depth of 231 cm. The results indicated that mass and length of roots with diameter
0.5–2.0 cm had a close correlation with branch mass. Mass and length of roots with diameter 2.0–10.0 cm closely correlated
to stem mass. Stem mass, root mass and root length closely correlated to DBH. A rather low correlation was found between DBH
and mass of branches and below-ground stump. DBH was a suitable variable for predicting total biomass. 相似文献
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139.
5年生马尾松造纸工艺林密度试验结果表明:平均树高受造林密度的影响较小,在一定密度范围内平均胸径随造林密度的增大而减小;单位面积的材积、生物量随造林密度的增大而增大;综合林分生长、生物量结构和经济效益等因素,马尾松造纸工艺林造林密度3333株/hm2较为经济合理。 相似文献
140.
红皮云杉嫩枝扦插繁殖技术的研究 总被引:9,自引:0,他引:9
本文描述了红皮云杉嫩枝扦插繁殖技术。通过试验筛选出1种适合于红皮云杉嫩枝扦插的基质(插壤),2种使生根率达98%且根系发育良好的生根剂。同时,提出了把握扦播时机,合理运用生根剂浓度及处理时间的方法和技术措施。 相似文献