油松水源保护林人工诱导更新与定向恢复机理

Mechanism of directive restoration artificially induced by creatin gaps in Pinus tabulaeformis of protection forest for water resources.

以油松水源保护林为对象,进行人工诱导更新与定向恢复机理研究.结果表明,在郁闭林分内油松更新苗密度平均为5 375株·hm-2,更新苗年龄为1～2年,而在人工Gap'效应岛'样地内,更新苗密度平均为17 062.5株·hm-2,其中1～2年、3～4年、5～6年生更新苗分别占73.44%,13.97%和12.59%;生长季光照强度在0、1.5和2.0 m三个不同高度梯度上,在Gap内部的平均值分别为289.0×100、542.0×100和589.0×100 lux,在对照林分内分别为139.0×100、146.0×100和246.0×100lux;从夏季观测到的空气温度平均值日变化分析,在白天Gap内的温度高于郁闭林分内部,温差可差2～3℃,在夜间Gap内的温度低于郁闭林分内,温差可差0.5～1℃;在白天6:00～11:00,人工Gap'效应岛'内空气湿度明显低于郁闭林分内,在其它时间段大致相当;对于同一层次土壤而言,Gap内的土壤温度明显高于郁闭林分内且变化幅度大,在0、10和20 cm三个梯度上Gap与郁闭林分相比土壤温度最大差值分别可达10、5和2℃;0～10、10～20和20～30 cm三个层次平均土壤含水量在Gap内分别为16.9%、15.1%和12.3%,在郁闭林分内分别为14.6%、12.5%和9.9%.总体上比较二者的光照强度、空气温度、空气湿度、土壤温度、土壤水分等有显著差异,因此人工Gap'效应岛'的创建是诱导其内部微环境因子变化的基础,也是油松水源保护林定向恢复更新的机理之所在.

Mechanism of directive restoration artificially induced by creating gaps in Pinus tabulaeformis plantations of protection forest for water resources was studied. The seedling density regenerated in closed stands is 5 375 ind· m^- 2, which age was 1 - 2 yr-old. In artificial gaps, the seedling density was 17 062.5 ind.· m^-2, in which 1 -2-yr-old seedling, 3-4-yr-old seedling and 5- 6-yr-old seedling were 73.44 %, 13.97 % and 12. 59%, respectively. Daily light intensity in growth season at the height of 0 m, 1.5 m, 2.0 m was 289.0 × 100 lux, 542.0 × 100 lux and 589.0 ×100 lux respectively in the gap, and 139.0 × 100 lux, 146.0 ×100 lux and 246.0 × 100lux in closed stand, respectively. In daylight, average air temperature in gaps was higher than that in closed stands in summer at the same time, and the difference was about 2-3 ℃. At night, average air temperature in gaps was less than that in closed stands in summer, and temperature difference was about 0.5 - 1 ℃C ;Average air humidity in gaps was higher than that in closed stands at 6：00-11：00 AM in daylight and almost similar in other times a day. Soil temperature in the gaps was higher and change more acutely than that in closed stands in the same depth. The maximum extent of soil temperature difference between gaps and closed stands in 0cm, 10cm, 20cm depth was 10 ℃, 5 ℃ and 2 ℃, respectively. Average soil water content in the layers of 0- 10 cm, 10 - 20 cm, 20- 30 cm was 16.9 %, 15.1% and 12.3 % respectively in the gaps, and 14.6 %, 12.5 % and 9.9% in closed stands. The result showed that the artificial gaps, created as disturbance patch through cutting the trees in the closed stands, induced the changes of the value of ecological factors such as light intensity, air temperature, soil temperature, soil water content, and then caused to accelerate the regen- eration of Pinus tabulaeformis in the gaps.