香港山坡地草本、灌木群落的植物能量生产

利用收获法和植物热值分析,在研究香港桃金娘灌木群落、芒萁群落和鸭嘴草+野古草+金茅草地植物的生物量和净生产量的基础上,探讨群落各组分的干重热值以及植物能量现存量、净固定量和现存净增量.结果表明,芒萁具有较高的热值,而禾草植物的干重热值较低.草地、芒萁、灌木群落植物的能量现存量分别为18683、38436和65632kJ·m^-2;能量净固定量为13286、20354和18784kJ·m^-2·a^-1;能量现存净增量为3437、9626和6695kJ·m^-2·a^-1.与地带性植被南亚热带常绿阔叶林相比,草地、芒萁、灌木群落的能量现存量、能量净固定量和能量现存净增量都较低.刈割实验也表明,随着人类干扰活动强度加大,植物能量净固定量明显下降.

Energy production of plants in grass, Dicranopteris dichotoma and Rhodomyrtus tomentosa communities in Hong Kong

With harvest method and caloric value analysis, this paper studied the caloric values, standing energy, net fixed energy and net standing energy increment of three plant communities i.e., grass, Dicranopteris dichotoma and Rhodomyrtus tomentosa, in Hong Kong. The results showed that the caloric value was higher in D. dichotoma community and lower in grass community. The standing energy of plants in grass, D. dichotoma and R. tomentosa community was 18,638, 38,436 and 65,632 kJ.m-2; net fixed energy was 13,286, 20,354 and 18,784 kJ.m-2.yr-1; and net standing energy increment was 3437, 9626 and 6695 kJ.m-2.yr-1, respectively. Compared with southern subtropical evergreen broad-leaved forest, the standing energy, net fixed energy and net standing energy increment were lower in grass, D. dichotoma and R. tomentosa communities, which resulted from deforestation and other human disturbance. This indicated that vegetation conversion due to human disturbance would reduce the utilization coefficient of solar energy. Net fixed energy was also found to be reduced significantly with increasing intensity of human disturbance.