Abstract: Four types of forests (i.e., deciduous coniferous forest, evergreen coniferous forest, deciduous broadleaved forest and shrub) are distributed in Xinjiang. Forest coverage is only 2% of vegetation area, but the forests play an important role in social effects, economic returns and ecological benefits. The forests in Xinjiang were firstly classified with an expert classification method based on the seasonal change of NDVI curves of the forest types and the GIMMS NDVI datasets during the periods of 1982-1984, 1984-1988, 1989-1993, 1994-1998, 1999-2003 and 2004-2006, and then the changes of area, growing stock volume and density of the forests as well as their affecting factors were analyzed. The results show that the forest area and the growing stock volume were increased by 5.83×10⁵ hm² and 4.02×10⁷ m³ in recent 25 years respectively, and the forest density was increased with an annual increase rate of 0.019%, indicating that the forests in Xinjiang were developed in a virtuous circle. Moreover, the forest density of deciduous broadleaved forests was decreased with an annual change rate of -0.62%, while the growing stock volume of deciduous broadleaved forests was increased because of the enlargement of plantation area. Therefore, both afforestation and reforestation can significantly contribute to the conservation of ecological environment in arid Xinjiang.

Key words: forest, growing stock volume, density, remote sensing, vegetation, dynamic change, NDVI, Xinjiang