光照与温度对云杉和红桦种子萌发的影响

通过在气候箱内模拟迹地环境条件，探讨了不同温度和光照对亚高山针叶林采伐迹地关键种种子萌发的影响．结果表明，云杉和红桦种子萌发的最适温度均为25℃，发芽率分别为88．8±8．4％和30．8±10．4％，多重比较显示红桦对温度的响应比云杉更敏感．云杉在10℃时能萌发而红桦则几乎不能．红桦种子萌发所需要的最低温度比云杉的高．昼夜温差对两类种子发芽影响明显，20℃／15℃条件下两种种子萌发率最高，温差过大不利于红桦种子萌发．光照强度对种子的发芽率也有明显影响。二者在透光20％时种子发芽率最高，分别为83．2±6．6％和29．2±5．5％，云杉种子萌发对光照的响应比红桦种子更为敏感．采伐迹地强烈的光照是限制亚高山针叶林自然更新的重要因素，迹地温度升高有利于云杉和红桦种子萌发，但剧烈的昼夜温差又在一定程度上抑制了种子萌发。

Effects of light and temperature on seed germination of Picea asperata and Betula albo-sinensis

The effects of different light and temperature conditions on seed germination of two keystone species (Picea asperata and Betula albo-sinensis) in subalpine coniferous forests were studied by simulating environmental conditions in climatic chambers. The results indicated that the optimal temperature of seed germination for both species was 25 degrees C, with the germination rate of 88.8 +/- 8.4% and 30.8 +/- 10.4%, respectively. Through multiple comparisons with Tukey's HSD, B. albo-sinensis was more sensitive to temperature than P. asperata. Seeds of P. asperata could germinate when the temperature reached 10 degrees C, but those of B. albo-sinensis could not, which implied that the latter as a pioneer species of subalpine coniferous forest areas needed higher lowest temperature for seed germination. Day and night temperature difference (15 degreesC/10 degrees C, 20 degrees C/15 degrees C and 20 degrees C/10 degrees C) had significant effect on the germination rates of tested seeds, which was the highest under 20 degrees C/15 degrees C. A wide range of day and night temperature difference seemed to be unfavorable to the seed germination of B. albo-sinensis. Light intensity also had a marked effect on the germination rates of test seeds. Under 20% transmittance, the germination rate of P. asperata and B. albo-sinensis was the highest, being 83.0 +/- 6.6% and 29.2 +/- 5.5%, respectively, and the initiation time and regularity of germination were the best as well. Furthermore, B. albo-sinensis was less sensitive to light than P. asperata, which was determined by the life behavior of tree itself.