Hurricane Recovery Plots at Harvard Forest 1937-1991

The New England hurricane of 1938, by destroying many acres of mature and semi-mature forests, initiated new forest associations over a large area. Permanent plots were established across the Harvard Forest in severely damaged stands (many of which were logged subsequent to the hurricane) to assess forest succession. Most of the plots involved successions following the blowdown of white pine on glacial till or outwash soils. From 1940 - 1948, and in 1978 and 1991, tree density and presence/absence of herb and shrub species were tallied. Pioneer species regenerating from seed and advance regeneration of longer-lived species quickly established at the sites; hemlock was the only species successfully regenerating after year 10, and most tree species were present within 2-4 years of the hurricane. By 1978, pioneer species such as gray birch and pin cherry declined or disappeared and red maple, white pine, paper birch and red oak dominated the plots. By 1991, most understory species present before the hurricane had returned, although there was a small group of understory species that apparently were more sensitive to disturbance and did not recover.

1938年新英格兰飓风摧毁了数千英亩成熟与半成熟森林，在大范围区域内催生了全新的森林群丛。科研人员在哈佛森林（Harvard Forest）内受飓风严重破坏的林分（其中多数林分在飓风后遭到采伐）中设立永久样地，以评估森林演替过程。多数样地聚焦于冰碛土（glacial till）与冰水沉积土（outwash soils）上的北美白松（white pine）风倒后的演替过程。研究分别于1940年至1948年、1978年及1991年开展，对样地内的树木密度，以及草本、灌木物种的存在与否进行了统计记录。由种子萌发的先锋物种与长寿物种的先期更新苗迅速在样地定植；飓风发生10年后，仅铁杉（hemlock）仍可成功完成更新，而多数乔木物种在飓风后2至4年内便已出现。至1978年，灰桦（gray birch）、苦樱桃（pin cherry）等先锋物种逐渐衰退甚至消失，红枫（red maple）、北美白松、纸桦（paper birch）与红栎（red oak）成为样地优势树种。至1991年，飓风发生前存在的多数林下物种已恢复，但仍有一小部分林下物种对干扰较为敏感，未能完成种群恢复。