Abstract
The sandy-hilly region of northwest Shanxi is a typical fragile agro-pastoral ecotone in north China. With the artificial Caragana korshinskii at 0 (the uncultivated land), 6, 12, 18, 40 and 50 years-old in the typical sandy-hilly region of northwest Shanxi as the subjects, we investigated soil moisture, aboveground and belowground biomass, individual morphological characteristics, growth, reproduction, and photosynthetic physiological characteristics of different-aged C. korshinskii, with the aim to evaluate the long-term growth and reproductive dynamic characteristics of artificial C. korshinskii. The results showed that soil moisture was significantly affected by stand ages. Soil moisture was low under the 6-year-old C. korshinskii plantation. During 6-18 years-old, soil moisture increased due to the increased crown width and reduced the near-surface wind speed, solar radiation, and soil water evaporation. During 18-50 years-old, soil moisture decreased sharply due to higher biomass and plant transpiration of C. korshinskii, and soil moisture was reduced to the lowest level of 11.1%. C. korshinskii mainly developed underground root system during 6-18 years-old, and changed to the aboveground biomass accumulation in 18-40 years-old. At the 40-year-old stand, biomass reached to the highest level with the greatest crown width and plant height. During 40-50 years-old, crown width and plant height decreased significantly, while the growth began to degrade. Photosynthetic capacity (chlorophyll a, b, carotenoid and total chlorophyll content) gra-dually decreased with the increases of planting ages, especially after 18 years-old. The quantity and quality of C. korshinskii seeds increased from 6 to 40 years-old, reached the maximum at 40 years-old stand, and began to decrease after 50 years-old. In the later growth period (30-40 years-old), more seeds with small individual weight were produced compared with early period (6-12 years-old). The germination test showed that small seeds had higher germination rate than the large ones under the same stand age, suggesting a shift of reproduction strategy. After 50 years-old, both of the growth and reproduction of C. korshinskii degenerated, and the plantation began to degrade.
Published Version
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