Transpiration rates of one-year-old seedlings of Pinus densiflora, Quercus glauca and Zerkova serrata and zero-year-old seedlings of Caragana korshinskii, a native Chinese xerophyte species, growing under well irrigated conditions were measured for 2 or 3 days in July, August and September of the first year and for about one month in May and July of the following year. Transpiration rates per day varied due to the effects of daily changes in weather condition. Mean daily transpiration rates of P. densiflora and Q. glauca were 5 to 8 g/dry leaf weight and 7 to 8 g/dry root weight. Seasonal decreases in transpiration rate of Z. serrata were detected in both years. C. korshinskii yielded a daily transpiration of about 40 g/dry leaf weight, which was 5 to 7 times higher than those of P. densiflora and Q. glauca. However, the amount of daily transpiration per dry root weight of C. korshinskii was almost the same as that of the other species. The relationships between transpiration rate and some environmental factors were also studied. Transpiration rates of P. densiflora and Q. glauca were found to be more significantly affected by air temperature than by relative humidity. On comparison, transpiration rates of Z. serrata and C. korshinskii were seldom affected by air temperature, and it appeared that humidity mainly determined the amount of transpiration of both species. The effects of leaf elongation periods for each species on the differences of responses of transpiration to environmental factors were discussed.

View full abstract

Vegetation recovery after fire in Cryptomeria japonica forests was investigated in northern Kanto, Japan. A lot of plants appeared at the burnt sites by the first summer. Some plants such as Commeline communis, Lespedeza bicolor f. acutifolia, Macleaya cordata and Erechtites hieracifolia germinated from survived seeds in the soil, and most of them were not found at the control (unburnt) forests neighbouring the burnt forest areas. A number of plants (e.g., Callicarpa japonica, Oplismenus undulatifoliusvar.japonicus, Quercus serrata, and others), however, recovered by sprouting from vegetative oganes, and they usually existed at the unburnt areas. The floristic composition at the burnt sites in the second year was not so different from that of in the first year. But the aboveground biomass of the former was three times more than the latter, and perennial and woody plants originating from the buried seeds were the most important species contributed to the increase.

View full abstract