Timing and extent of forest disturbance in the Laurentian Mixed Forest
Timing and extent of forest disturbance in the Laurentian Mixed Forest
复制标题
DOI：
10.3389/ffgc.2022.963796
复制
发表时间：
2022-08-24
影响因子：
3.2
通讯作者：
Westfall, James A.
中科院分区：
文献类型：
--
作者：
Edgar, Christopher B.;Westfall, James A.
对美国国家森林资源清单在劳伦特混交林的观测结果进行的分析显示，1999年至2015年期间，森林干扰显著增加。劳伦森溷合林省生态亚区横跨密歇根州、明尼苏达州和威斯康星州的北方部分，森林面积在1670万至1750万公顷之间，具体取决于年份。森林干扰范围从2000年的13万公顷（森林面积的0.8%）到2014年的209万公顷（森林面积的11.9%）。值得注意的是，2015年是自2000年以来森林干扰下降的第一年，尽管幅度不大（森林面积的11.4%）。这种显著增加是由于在两次重新测量之间随着时间的推移不断发生干扰。年平均最高的干扰是树木虫害、树木病害和鹿/有蹄类动物，分别为每年29.1万公顷、18.9万公顷和12.6万公顷。在某一年发生的扰动，我们称之为离散扰动，在这一时期内没有明显的趋势。最广泛的离散扰动是1999年、2011年和2012年的风，分别为10.8万、6.2万和6.1万公顷。国家森林清查的标准估计数缺乏对实际干扰年份的具体说明。此处报告的估计数为干扰的实际年度估计数，该估计数应用了干扰观测的追溯性质的估计方法。两次最广泛的风事件的时间（年份）和位置（生态部分）与历史记录一致。
An analysis of United States national forest inventory observations in the Laurentian Mixed Forest reveals a marked increase in forest disturbance between 1999 and 2015. The Laurentian Mixed Forest Province ecological subregion spans the northern sections of Michigan, Minnesota, and Wisconsin and includes forest area of between 16.7 and 17.5 million hectares depending on the year. Forest disturbance ranges from a low of 0.13 million hectares (0.8% of forest area) in 2000 to a high of 2.09 million hectares (11.9% of forest area) in 2014. The year 2015 is notable for being the first year since 2000 where forest disturbance declines, albeit modestly (11.4% of forest area). The marked increase is attributable to disturbances occurring continuously over time between remeasurement. Disturbances with the highest annual averages are insect damage to trees, disease damage to trees, and deer/ungulate at 291 thousand, 189 thousand, and 126 thousand hectares per year, respectively. Disturbances occurring in a specific year, what we term discrete disturbances, show no discernible trend during the period. The most extensive discrete disturbances are wind in 1999, 2011, and 2012 at 108 thousand, 62 thousand, and 61 thousand hectares, respectively. Standard estimates from national forest inventory lack specificity as to the actual year of the disturbance. The estimates reported here are actual annual estimates of disturbance that apply estimation methods accounting for the retrospective nature of the disturbance observation. The timing (year) and location (ecological section) of the two most extensive wind events coincide with historical records.