[Spatiotemporal dynamics of forest carbon storage in Taihe County of Jiangxi Province in 1985-2030].

Based on the sixth forest inventory data of Taihe County, Jiangxi Province, this paper analyzed the curve relations between the carbon densities and ages of major forest types by using Logistic equation, and estimated the total amounts and change trends of the biomass and carbon storage of forest vegetation from 1985 to 2003 by the method of biomass expansion factor. The carbon storage in 2020 and 2030 was estimated by setting 2003 as the baseline year and assuming that the area of forest vegetation remained stable and without consideration of forest rotation. In 2003, the total forest area of Taihe County was 15.74 x 10(4) hm2, the total biomass was 6.71 Tg, the vegetation carbon storage was 4.14 Tg C, and the average carbon density was 26.31 t C x hm(-2). In 1985, 1994, 2003, 2020, and 2030, the forest carbon storage was 1.06, 2.83, 4.14, 5.65, and 6.35 Tg C, respectively. The carbon density of the forest vegetation in Taihe County decreased from the eastern and western regions to the central. Artificial afforestation contributed significantly to the increase of forest stand area, and consequently, to the improvement of forest carbon sequestration capacity.

[Carbon losses from forest fire in Jiangxi Province, China in 1950-2008].

The annual occurrence of forest fire in Jiangxi Province of China in 1950-2008 was averaged 762 times and covering 1.578 x 10(4) hm2. Based on the forest fire statistic data, meteorological data, forest inventory data, and other parameters, this paper analyzed the characters of forest fire in the province, and estimated its carbon release and transfer. In the province, the total forest biomass loss from forest fire in 1950-2008 was about 61. 155 Tg, and the biomass carbon loss was about 30.993 Tg C, accounting for 15.92% of the vegetation carbon pool in the whole province. Before the 1970s, the biomass carbon loss occupied 74.3% of the total loss in 1950-2008, but after the 1990s, this loss decreased rapidly, with an annual average carbon loss less than 0.097 Tg C. The released CO2, CH4, and CO from the forest fire were about 5.408 Tg, 0.047 Tg, and 0.486 Tg, respectively, and led to 22.436 Tg of biomass carbon transferred into soil carbon. The snow and ice disaster in the beginning of 2008 resulted in high frequency forest fire, and led to a 0.463 Tg biomass carbon loss, which was 2. 56 times of the average value (0.181 Tg) in 2003-2007.

Assessment of effects of climate change and grazing activity on grassland yield in the Three Rivers Headwaters Region of Qinghai-Tibet Plateau, China.

Inter-annual dynamics of grassland yield of the Three Rivers Headwaters Region of Qinghai-Tibet Plateau of China in 1988-2005 was analyzed using the GLO-PEM model, and the herbage supply function was evaluated. The results indicate that while grassland yield in the region showed marked inter-annual fluctuation there was a trend of increased yield over the 18 years of the study. This increase was especially marked for Alpine Desert and Alpine Steppe and in the west of the region. The inter-annual coefficient of variation of productivity increased from the east to the west of the region and from Marsh, Alpine Meadow, Alpine Steppe, Temperate Steppe to Alpine Desert grasslands. Climate change, particularly increased temperatures in the region during the study period, is suggested to be the main cause of increased grassland yield. However, reduced grazing pressure and changes to the seasonal pattern of grazing could also have influenced the grassland yield trend. These findings indicate the importance of understanding the function of the grassland ecosystems in the region and the effect of climate change on them especially in regard to their use to supply forage for animal production. Reduction of grazing pressure, especially during winter, is indicated to be critical for the restoration and sustainable use of grassland ecosystems in the region.