关键词: 株行距, 齐穗期, 冠层结构, 消光系数, 光合特性, 产量

Abstract: By using rain gauge, membrane filter, CO₂ monitoring tube, and standard corrosion tablet, this paper measured the rainfall, suspended sediment content, soil CO₂ concentration, and soil corrosion rate in forest ecosystem and shrub ecosystem in Luota of west Hunan Province. The rainfall in forest ecosystem was larger than that in shrub ecosystem, being 6.84 mm higher in the first observation year and 218.08 mm higher in the second year. There was a serious soil and water loss in shrub ecosystem, and the sediment content in the ecosystem was 1.53 times of that in forest ecosystem. The soil erosion was intensive in shrub ecosystem but slight in forest ecosystem. The CO₂ concentration in different soil layers in forest ecosystem and shrub ecosystem had the same change trend, i.e., increased with the deepening of the soil layer in spring, autumn, and winter while increased after an initial decrease in summer. In forest ecosystem, the soil CO₂ concentration in different layers and in different seasons was larger than that in shrub ecosystem. According to the comparison throughout the year, the soil CO₂ concentration at the depths 10, 20, and 40 cm in forest ecosystem was 1.66, 1.59, and 1.90 times of that in shrub ecosystem, respectively. In different soil layers, the corrosion rate in forest ecosystem and shrub ecosystem had the same change trend, being larger at the depth 15 cm than on the soil surface. In the same soil layers, the corrosion rate was faster in forest ecosystem, being 1.11 and 2.57 times of that on the soil surface and at the depth 15 cm in shrub ecosystem, respectively. Our results suggested that there existed better karst effect in the forest ecosystem.

Key words: spacing, full heading stage, canopy structure, extinction coefficient, photosynthetic characteristics, yield.