Response of Pinus koraiensis seedling growth to different light conditions based on the assessment of photosynthesis in current and one-year-old needles |
| |
| Authors: | Jiaojun Zhu Kai Wang Yirong Sun Qiaoling Yan |
| |
| Institution: | 1. State Key Laboratory of Forest and Soil Ecology, Qingyuan Experimental Station of Forest Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China
2. University of Chinese Academy of Sciences, Beijing, 100039, China
|
| |
| Abstract: | As one of the three major five-leaved pines in the northern hemisphere, Pinus koraiensis is the most important dominant tree species in the natural mixed-broadleaved Korean pine forests. However, the regeneration of P. koraiensis under the canopy of secondary forest stands is poor because of the light limitation. This study was conducted to understand how P. koraiensis seedlings adapt to different light intensities and what would be the optimum light level for their establishment and growth. Three repetition plots with four light intensities (15%, 30%, 60% and 100% of the natural incident irradiances, achieved by suspending layers of black nylon net above and surrounding the plots) were set up under natural climate conditions in a montane region in eastern Liaoning Province, Northeast China. A total of 80 P. koraiensis seedlings with similar height and root collar diameter were transplanted into four plots. After one year of acclimation to the specific light conditions, the seasonal variations of the photosynthetic variables and needle traits of the current and one-year-old needles, and the growth parameters were observed under four light intensities. The results indicated that: (1) The seedling at 60% treatment exhibited the greatest growth, which agreed with the response of the light-saturated photosynthetic rates (A max) and the dark respiration rate (R d) in the current and one-year-old needles, i.e., R d at 60% treatment was significantly lower than that at 100% treatment, but A max did not differ between the seedlings at 100% and 60% treatments. (2) The P. koraiensis seedlings have a certain photosynthetic plasticity to adapt the light conditions by adjusting their needle traits and regulating the physiological processes, because A max, R d, light saturation point and compensation point, the needle mass area, needle nitrogen and chlorophyll contents were significantly (p<0.05) correlated with the light intensities. Especially, A max at 100% and 60% treatments was significantly higher (p<0.05) than that at 30% and 15% treatments for both current and one-year-old needles. (3) The needles of different ages played a commutative role during the growing season, i.e., the one-year-old needles played a major role for the photosynthesis in the early growing season; the current year needles did in the later growing season. This ensured the effective photosynthesis throughout the growing season. These findings suggest that P. koraiensis is the in-between heliophilous and shade-tolerant tree species at least for the seedlings up to 8 years. |
| |
| Keywords: | light requirement needle age needle trait photosynthetic plasticity Pinus koraiensis |
| 本文献已被 CNKI 维普 SpringerLink 等数据库收录！ |
|
