摘要
本项研究指出,在晴天条件下,由于土壤水分含量不同,羊草和大针茅的光合作用日进程呈现出两种类型:在土壤水分充足时,为午前高峰型;在土壤干旱时,为双峰型。两者均属于光合作用午间降低的类型。 两种植物相比,在土壤干旱时,羊草比大针茅光合午间降低幅度大得多;在土壤水分充足时,其降低程度相近。无论土壤含水量高低,大气湿度降低均是引起光合午间降低的主要大气生态因子。所不同的是,强光只有在土壤干旱时才是引起光合午间降低的直接生态因子;因此,午后光合高峰的出现是光强下降所致。土壤水分亏缺与大气低湿相配合,加剧了光合午间降低的程度,其降低幅度随着土壤水分的减少而增大。因此,增加土壤水分是减缓光合午间降低程度的主要生态途径。
This study shows that under fine-weather conditions due to difference of soil moisture content the diurnal course of photosynthesis of Aneurolepidium Chinense and Stipa Grandis has two types. When the soil moisture is sufficient, there is the monopeak type with a peak occurring before midday. When the soil is dry, there is the double peak type. In both the two types, the photosynthesis is low at midday.A comparison has been made between the two species, When the soil is dry, the decline in photosynthesis of Aneurolepidium Chinense at midday is much greater than that of Stipa Grandis. When the soil is sufficient, their declines are sinilar. No matter what the soil moisture condition may be, the low atmospheric humidity is a main ecological factor of the decline in photosynthesis at midday. The intense sunlight is a direct ecological factor of the decline in photosynthesis at midday only when the soil is dry. So the occurrence of the peak after midday is due to the decline in intensity of the sunlight.The dry soil and the low atmospheric humidity together increase the degree of the decline in photosynthesis at midday. The range of decline increases as the soil moisture decreases. Therefore, increasing the soil moisture content is the main ecological way to decrease the degree of decline in photosynthesis at midday.
出处
《自然资源学报》
CSSCI
CSCD
1990年第2期177-188,共12页
Journal of Natural Resources
关键词
羊草
大针茅
光合作用
生态因子
decline in photosynthesis at midday
ecological factor
Aneurolepidium Chinense
Stipa Grandis
