TAMAI Shigenobu Instructor, Fac. of Agriculture, Kyoto University, 農学部, 助手 (60026606)
CHIBA Kyozo Professor, Fac. of Agriculture, Okayama University, 農学部, 教授 (10036741)
KATAGIRI Shigeo Associate Professor, Fac. of Agriculture, Shimane University, 農学部, 助教授 (00032649)
李 昌華 中国科学院, 自然資源総合考察委員会, 副研究員
IWATSUBO Goro Associate Professor, Fac. of Agriculture, Kyoto University, 農学部, 助教授 (00026395)
LI Changhua Associate Professor, The Chinese Academy of Sciences
Forest ecological studies on water and mineral cycling through forest ecosystems were carried out in severely eroded land and in natural evergreen broadleaved forest in Jiangxi Provinco, China, 1987.
In 1988, the discussions were carried out on the results obtained in China. first, all japanese member got together in Kyoto on sept. 1988, to present the results of each subject and to discuss. Second, Dr. G. Iwatsubo, one of the staff member, visited china to talk about our result of discussion with the member of Chinese side, on Oct. 1988. Third, head investigator discussed again on the summerized report with some of Japanese member from Dec. 1988 to Feb. 1989. Finally, the draft of the first leport was prepared on middle of March 198.. This draft will be published soon.
The outline of the draft is as follows;
In severely eroded area, the experimental plot were set up in young pine(pinus massoniana) stands for investigate the effect of litter and undergrowth removal and fertilization on th
e rate of recovery of soil. The biomass of pine stands studied were equivalent to that of the poorest site of pine forest in Jiangxi Province. The leaves biomass was very low and undergrowth was very thin and poor. This implies that the human impacts are still active in this area. The accumulation of _0 layer, and of carbon, nitrogen and available minerals in soil are also very poor. There was no evidence of soil recovery.
In natural evergreen broadleaved forest at Jiulianshan, the small experimental watershed for the studies on water and mineral cycling was set up in nature reserve area. the vegetation in this watershed was classified into three types, that is, castanopsis forest, Schima Forest and Pine forest. Castanopsis forest developed mainly on lowerslope of northern slope. Pine forest was on upperslope or ridge where soil is usually shallow and dry. Schima forest develop on the intermediate site between above two. Two plots were set up in Castanopsis forest and Schima forest on lowereslope for investigate the internal cycle of nutrients. The biomass of the stands was estimated using the allometoric relationships. The above ground part was 396 and 308 t/ha and basal area was 48.6 and 42.3 m^2/ha, respectively. the stem increment was estimated as 10.8 and 9.9 t/ha yr.
The chemical analysis of evergreen broadleaved trees was carried out and mineralmass of trees was estimated. Nitrogen accumulation was higher than that of the evergreen broadleaved forest in Japan. Soil in the studied area could be identified as "Red Yellow Soil". The accumulated carbon in mineral soil is ranged from 53 to 90t/ha. 70cm, and that of nitrogen was from 3.4 to 8.9t/ha, 70cm. The amount of exchangeable Ca and available P were rather low. The total accumulations, sum of trees and soil, are 7.1-10.0t/ha for nitrogen, 1826-2383kg/ha for Ca and 446-562kg/ha for Mg, respectively.
At Jiulianshan, the annual mean precipitation, temperature and pan evaporation are 1825mm, 16.5 c and 865.4mm, respectively. The warmth index is 136 c mo.. The daily temperature during the winter has wider fluctuations than 20 c, and sometimes it decrease below 0 c. The climatic condition differ from that in the Japanese lucidophyllous forest. Less