Guangcai Chen

Carbon sequestration of black locust forests in the Yellow River Delta region, China

The Yellow River Delta region in China is a land area of 1,200,000 ha with rich natural resources. Adverse environmental conditions, such as low rainfall and high salinity, promote the dominance of black locust trees for afforestation. With the increase of CO2 in the atmosphere, this forest and others throughout the world have become valued for their ability to sequester and store carbon. Forests store carbon in aboveground biomass (i.e. trees), belowground biomass (i.e. roots), soils and standing litter crop (i.e. forest floor and coarse woody debris). There are well-developed methods to sample forest ecosystems, including tree inventories that are used to quantify carbon in aboveground tree biomass. Such inventories are used to estimate the types of roundwood products removed from the forest during harvesting. Based on standard plot inventories and stem analyses, carbon sequestration estimates of trees were 222.41 t ha−1 for the Yellow River Delta region accounted for 67.12% of the whole forest. Similarly, carbon storage by herbaceous matter and soil was 0.50 and 50.34 t ha−1, respectively. The results suggest that carbon sequestration in the forest ecosystem was performed by most of the forest, which plays an increasingly important role in sequestering carbon as the stand grows.

Water shortages and countermeasures for sustainable utilisation in the context of climate change in the Yellow River Delta region, China

With an increasing population and rapid development of the economy and society of the Yellow River Basin region, the Yellow River is at crisis point. The discrepancy between supply and demand of water resources is a key issue. In 2000–2006, the mean annual discharge of the Yellow River entering the delta was 13.2 billion m3, a reduction of 18.6 billion m3 compared with the 1980s, and 9 billion m3 less than in the 1990s. The water requirements of various sectors are increasing. Large amounts of water essential to maintain the health of the delta ecosystem have been diverted for other users. The lower river channel is shrinking and the threat of flooding is becoming severe. Moreover, water pollution is increasing to a serious level; the river mouth ecosystem is subject to degradation. Due to overall decreased flow into the delta, and almost no flow into the delta for much of the year except in wet periods, biodiversity is threatened and there has been degradation of the ecological environment. In view of the water scarcity and variation in water supply, particularly in the context of climate change, measures need to be taken to realise sustainable water use in the Yellow River Delta region. In view of the lack of a complete index system for sustainable utilisation of regional water resources in China, this paper examines the major countermeasures for sustainable water use in the region. A rational adjustment mechanism for water prices is needed. Adjustment of agricultural infrastructure and water saving need to be directed by water prices, and thus the reasonable exploitation of groundwater must also be directed by water prices. Participation of the public is to be encouraged, with the development of a water user association that will become involved in formulating water rights, water allocation and water prices. Decision-making, management and supervision of this association will be done in a democratic way to promote the social management of water saving.

Soil salinization and ecological remediation by planting trees in China

With world population growth, the demand for food, vegetable and so on is increasing. However, arable land area cannot expand. Moreover it would decrease owing to land use change with socio-economic development. Especially in China that is the most populated country in the world, while its cultivated land area could not match with the population, farmland is gradually declining with urbanization progress. In order to meet the demand to grain production and alleviate the pressure on current arable land, wasteland must be reclaimed. Forestation is not only one way for saline-alkali soil utilization, but also can improve soil property and maintain ecological balance. Salt-affected soils extensively distribute on the earth. Although the causes are various for salinization occurrence, generally spoken it results from the accumulation of free salts to an extent that causes degradation of vegetation and soils. On the other hand, irrational human practices have increased soil salinity by changing the natural balance of the water cycle in the landscape by allowing excess recharging of groundwater. This reduces suitability to plant growth and increases the potential for other forms of land degradation such as soil erosion and structural decline. Thus salinization is one of the most serious long-term threats to the sustainability of land and water resources in the world. Trees can tolerant a certain level of salinity thanks of the nature. Therefore in the viewpoint of biological amelioration of salt-affected soil, planting trees is necessary and significant. After trees are established in saline land, the watertable could be declined through increasing discharge and decreasing recharge. Additionally total salt content could be decreased, especially in soil surface profile and topsoil as well as soil physical & chemical state could be ameliorated.

Forest biomass resources and utilization in China

Under the context of climate change, persistent high oil prices and rapidly growing dependence on imported oil prompt China to pay much more attention to biofuels that provide environmental benefits besides fuel. China has rich biodiversity with 30 thousand high plant species and 154 kinds of energy trees could produce seeds containing more than 40% of oil, with total production of the seeds totaling 5 million t, and 200 x10 9 t of biomass production per year, which is equal to 2 x 10 9 xa0t of petroleum. There are over 2000 types of wild and cultivated firewood plants in the country. So far there is 4 million ha raising oil-bearing trees planted on some land in different regions. Another 57 million ha of waste land are available and suitable for planting trees for the production of forest bioenergy. On part of these lands, the central government plans to cultivate a total of 13 million ha of high-grade bioenergy forests by 2020. This will yield 6 million tons of diesel that would be enough to fuel power plants with a combined capacity of 11 GW each year. Moreover, forest biomass plantations potentially offer many direct and indirect environmental benefits. In view of climate change their globally significant environmental benefits may result from using forest biomass for energy rather than fossil fuels. Key words : Biomass energy, China, forest biomass resources.

Countermeasures to Control Agricultural Non-Point Source Pollution in Headwaters of Taihu Lake Basin

Water pollution in Taihu Lake has become one of the most serious environmental problems that draws public attention and needs to be solved as soon as possible. It was well known that forest could play an important role to control soil & water erosion, uptake extra soil nutrients as well. However forest coverage is rather low and woodlands are extensively managed in the headwaters region. Thus the fertilizer loss resulted from the erosion of soil and water in sloping field has acted as an important role in the course. In view of the situation, enhancing forest establishment and management is significant. The primary objective of applying hedgerows is to control soil & water erosion, and improve farming conditions on slope field in headwater region of Taihu Lake basin. While building riparian forest buffer zone is helpful to protect riverbank, uptake nutrients, hold up pollutants and provide habitat for wildlife. The planting techniques of hedgerows in slop fields and riparian forest buffer zone along channels were discussed in the paper, which is considered as a vital measure to control agricultural non-point source pollution.

Potential and Future Prospects of Biomass Production in Saline Soils

Facing the challenge of petrolium price rising and energy consumption increasing, Chinese government has realised how urgently it needs an alternative solution. Under the banner of creating a harmonious society, the government is looking into new options for sustainable rural development, utilising resources more efficiently, prioritising new and renewable energy technologies with wider market applications. With its vast territory and diverse geographical regions, China has a large stock of biomass resources from agricultural and forest residues, as well as vast areas of saline land that can be used for bioenergy development. In this paper salt-affacted land resources and possible flora resources cultivated for biomass production were approached, as well as strategies to develop these saline soils. The potential of the countrys forest-based bioenergy would thus be equivalent to 200 million tons of coal, the utilization of which would reduce the consumption of fossil energy by 10 percent. It is concluded that the potential of biomass production through exploiting saline soils is large ans the prospects in future are bright, too.

Effect of Soil Salinity on Tree Growth in Yellow River Delta Region

At present the environment in Yellow River delta region is particularly badly eroded. In view of the situation, use of vegetation for environmental protection is most effective. In order to select suitable tree species, some physiological parameters such as proline content, ratio of bound water and free water, relative conductivity of leaves were applied to this experiment to probe the capability of trees to resist salinity stress. Based on the testing results, these tree species such as R. hispida, F. velutina, C. korshinskii, N. sibirica, T. chinensis, R. typhina, S. matsudana, A. fruticosa and A. altissima were chosen and planted in the area. The result of stand inventory implemented in the year showed that these trees grew well, especially for L. chinense, the biggest height increment reached 1.73 m, and the mean was 1.45 m; and the biggest basal diameter was 1.52 cm, the mean was 1.21 cm. Hence it was concluded that planting trees could prevent soils from salinization and protect lands from degradation.