Impacts of Climate Change on Forest Ecosystems in Northeast China

This paper reviews the studies and research on climate change impacts on the forest ecosystems in Northeast China. The results show that in the context of global and regional warming, the growing season of coniferous forests has been increasing at an average rate of 3.9 d per decade. Regional warming favors the growth of temperate broad-leaved forests and has a detrimental effect on the growth of boreal coniferous forests. Over the past hundred years, the forest edge of the cool temperate zone in the southern Daxing＇anling region has retreated 140 km northward. From 1896 to 1986, the northern boundary of broad-leaved forests in Heilongjiang province has extended northwestward about 290 km. Future climatic changes （until 2060） may lead to the northern deciduous needle forests moving out of China＇s territory altogether. The occurrence cycles of pests and diseases have shortened; their distribution ranges have expanded. The life cycle of tent caterpillars （Malacosoma neustria testacea Motschulsky） has shortened from 14-15 years in the past to 8-10 years now. The pine caterpillar （Dendrolimus tabulaeformis Tsai et Liu）, which has spread within western Liaoning province and the nearby areas, can now be found in the north and west. Lightning fires in the Daxing＇anling region have significantly increased since 1987, and August has become the month when lightning fires occur most frequently. Overall, the net primary productivity （NPP） of forest in Northeast China has increased. The NPP in 1981 was around 0.27 Pg C, and increased to approximately 0.40 Pg C in 2002. With the current climate, the broad-leaved Korean pine forest ecosystem acts as a carbon sink, with a carbon sink capacity of 2.7 Mg C hm-2. Although the carbon sink capacity of the forest ecosystems in Northeast China has been weakened since 2003, the total carbon absorption will still increase. The forest ecosystems in Northeast China are likely to remain a significant carbon sink, and will play a positive role in the mitigation of climate change.

Urban Regeneration： Better Cities for Sustainable Development

With the increasing growing of the environmental issues and climatic change, sustainable urban development of cities became an urgent demand. Urban development relied on four pillars; the institutional, social, environmental and economic pillars. Urban regeneration is not a single concept; it is a group of strategies. This study concluded that those strategies include; the public action, certification programs and corporate responsibility theories.

δ^(18)O and δD records of inactive ice wedge in Yitulihe, Northeastern China and their paleoclimatic implications

Discovered in the late 1980s, inactive ice wedges in Yitulihe in the north part of Da Hinggan Mountains, Northeastern China are the southernmost in the Northern Hemisphere, and they are important paleo-environmental indicators. Recently, research was carried out to analyze the hydrogen and oxygen isotopes of an inactive ice wedge from them. The plot of stable isotopes reveals three periods of temperature fluctuations centered approximately at 2.8, 2.3 and 1.9 ka BP. And the resultant temperature was probably lowered by about 2.1, 1.1, and 1.3℃, respectively, in comparison with present temperatures. In conjunction with previous studies, pollen record and radiocarbon dating, the ice wedges probably developed between 3.3 to 1.6 ka BP, and the southern limit of the permafrost （SLP） at that time advanced southwards by around 2°N, i.e., about 200 km.