摘要:
林火是对森林生态造成影响的最主要干扰因素之一,探究林火时空变化规律及森林恢复具有一定的社会学和生态学意义。大兴安岭拥有我国面积最大的原始林区,也是林火频繁发生的重点区域。本研究使用MODIS火烧迹地、土地覆盖以及总初级生产力(gross primary productivity,GPP)时间序列产品对大兴安岭2002—2021年火烧迹地分布信息进行提取,并对火后森林恢复情况进行统计。结果表明: 2002—2021年间,大兴安岭森林地区火灾次数整体呈下降趋势,但火烧迹地面积呈现波动性变化,其中2003年无论是过火面积还是火灾频率都为最高,2008年次之,2019年过火面积最小; 林火主要集中在春秋两季,3月过火面积和过火次数都为最高,9月的过火次数较高; 同时林火在空间上由东北向西南呈不均匀分布,主要集中在黑龙江大兴安岭地区和内蒙古呼伦贝尔市,且内蒙古地区的林火面积远远大于黑龙江地区。对过火地区的林种分析可知,阔叶林的过火区域最大,其次是混交林,最后是针叶林。通过对过火区域的GPP时间序列分析得出,一般灾后第一年GPP数值恢复最快,但需要近7 a时间才能完全恢复到过火前的生长水平,且不同森林类型在灾后恢复速度存在明显差异,阔叶林地恢复速度较快,其次是针叶林,之后是混交林。了解林火的时空分布能够为布置和调整防火、灭火力量提供数据支撑,灾后森林的恢复研究可为森林重建和持续发展提供科学依据。
Abstract:
Forest fires are one of the most significant disturbance factors affecting forest ecosystems. Exploring their spatio-temporal variations and forest restoration holds certain sociological and ecological significance. The Great Xing’an Range, possessing the largest primitive area in China, is a key area suffering frequent forest fires. Hence, this study extracted the distribution information of burned zones in the Great Xing’an Range from 2002 to 2021 from the MODIS time series products involving burned zones, land cover, and gross primary productivity (GPP). Moreover, it statistically analyzed the post-fire forest restoration. The results show that: ① Fires in the forest area of the Great Xing’an Range showed an overall downward trend from 2002 to 2021, but the burned areas showed fluctuating changes. Both the burned area and fire frequency were the highest in 2003, followed by 2008, with the lowest burned area seen in 2019; ② Forest fires occurred primarily in spring and autumn, with the highest burned area and fire frequency in March and the second highest fire frequency in September; ③ Forest fires manifested an uneven spatial distribution from northeast to southwest, predominantly in the Great Xing’an Range within Heilongjiang and Hulunbuir City of Inner Mongolia. Moreover, the forest fire area in Inner Mongolia far exceeded that in Heilongjiang. The analysis of forest types in burned zones reveals that the burned areas decreased in the order of broad-leaved, mixed, and needle-leaved forests. According to the time series analysis of GPP in burned zones, GPP values recovered the fastest in the first year post-fire, but it took nearly seven years to recover to the pre-fire growth level. Different forest types manifested significantly distinct post-fire restoration rates, which decreased in the order of broad-leaved, needle-leaved, and mixed forests. Overall, ascertaining the spatio-temporal distribution of forest fires can provide data support for the arrangement and adjustment of fire prevention and control efforts, while investigating the post-fire forest restoration can provide a scientific basis for the rehabilitation and sustainable development of forests.
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