关键词: 生态地理区, 林火动态, 火险期

Abstract:

[Objective] Fire is an important factor to drive the ecosystem development and change. Fire disturbance has influence on the patterns and processes vegetation dynamics. Fire regimes alter with changes in vegetation, climate and anthropogenic disturbance. Understanding the current fire regimes in ecological zones is the scientific basis for forest fire management. [Method] This paper divided the China mainland into eight regions based on the Eco-geographic classification system and the characteristics of forest fires, which arethe deciduous coniferous forest in the cold temperate humid region (R1), temperate humid forest zone (R2), temperate coniferous forest zone in arid desert region (R3), temperate grassland in semi-arid areas (R4), warm temperate moist/humid deciduous forests region (R5), temperate semi-arid/arid steppe region (R6), middle and north subtropical humid broadleaf forests and artificial vegetation region (R7), and south subtropical and tropical moist broadleaf forest and artificial vegetation region (R8), respectively. The spatial and temporal distribution of forest fires for each eco-geographical zones was analyzed according to the hotspot data from satellite monitoring and fire statistics in 2005-2012.[Result] The results showed that: The wildfires were mainly distributed in the eastern China, and those occurred in R8 accounted for 84.4% of the total. Wildfires in R1, R2, R3, R4, R5, R6 and R7 occupied 0.5%, 3.8%, 0.1%, 2.7%, 2.7%, 0.1%, and 5.8%, respectively. The fire seasons for each eco-geographical zone were defined based on the forest fire occurrence. The most forest fires occurred in spring and autumn in northern China, while they did in winter and spring for the south. The fire seasons for R1, R2, R3, R4, R5, R6, R7 and R8 were March-October, April-May and July-October, March-May and August-October, March-June and September-October, November-May, December-May, December-May, and November-May, respectively. Although more forest fires occurred in the tropical and sub-tropical moist regions, they were easy to be controlled. To the contrast, the wildfires occurred in the cold temperate humid region had a longer burning period than the fires in the south. The fire occurrences and burned areas for each eco-geographical zone showed significant volatility in 2005-2012. Human disturbance had a great impact on fire regimes, especially in southern China with high population density. The south subtropical and tropical moist broadleaf forest and artificial vegetation region had the highest fire frequency, and the average annual 6 489 fires with fire cycle of 4 547 years. While the fire frequency in the deciduous conifer forest region in the cold temperate humid region was 0.04 times·(10⁴ hm²)^-1, and the fire cycle 1 007 years was shortest. The fire regimes of the temperate humid forest zone and the temperate coniferous forest zone in arid desert region showed a similar tendency to that of the deciduous conifer forest region in the cold temperate humid region. The fire frequency in the warm temperate moist/humid deciduous forests region and the middle and north subtropical humid broadleaf forests and artificial vegetation region was 0.28 and 0.25 times·(10⁴ hm²)^-1, respectively. [Conclusion] The forest fires were mainly distributed in eastern China. The fire season occurred in the spring and autumn season in northern China, while it did in winter and spring for southern China. There was a high fire frequency in broad-leaved forest and artificial vegetation areas in tropical and subtropical humid region, and the shortest fire cycle in the deciduous coniferous forest in the cold temperate humid region.It is recommended to carry out a fuel management plan in accordance with the purpose of forest management and maintain the fire regime at a reasonable level for sustainable application of forest resources.

Key words: ecological zones, fire regime, fire season