Context

Historical land use is potentially the most important factor controlling composition and structure of temperate deciduous forests, but historical dynamics are not well understood at biologically relevant spatial and temporal scales.

Objective

To provide insight into the structure of second-growth forest communities in a post-agricultural landscape relatable to large areas of eastern North America.

Methods

Using point-sampling of historical aerial photographs, we document changes in the frequency and distribution of land covers in a section of the Ohio River Valley (USA). Data were collected at the scale of individual management units at 20-year intervals to test environmental and geographic factors controlling forest regeneration.

Results

Between 1939 and 2015, forest cover increased from 26 to 68% of the study area paralleling declines in cultivation and pasturing. The mean size of forest stands increased each decade, and distance to the forest edge increased between 1939 and 1980, potentially favoring recovery of interior-specialist species. Transition analysis revealed a sequence of agricultural relegation from cultivation to pasture to old-field to young forest to mature forest consistent with the economic value of individual plots. Most modern stands are 35–55 years old and situated on slopes. Only 12.7% of forest is > 120 years old.

Conclusions

Notwithstanding the increase in forest cover, comparison of stand distribution with long-term successional data suggests that land use history has concentrated forest-species diversity in a small number of relict stands. Management for biological diversity should focus on identifying and protecting relict stands rather than protecting second-growth forest in general.

中文翻译：

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塑造二次生长的森林：俄亥俄河谷 120 年来精细尺度的土地利用变化

语境

历史土地利用可能是控制温带落叶林组成和结构的最重要因素，但在生物学相关的空间和时间尺度上，历史动态尚未得到很好的理解。

客观的

深入了解与北美东部大片地区相关的后农业景观中的二次生长森林群落的结构。

方法

使用历史航拍照片的点采样，我们记录了俄亥俄河谷（美国）一部分土地覆盖的频率和分布的变化。以 20 年为间隔在各个经营单位的规模上收集数据，以测试控制森林再生的环境和地理因素。

结果

1939 年至 2015 年间，森林覆盖率从研究区域的 26% 增加到 68%，同时种植和放牧减少。林分的平均规模每十年增加一次，到森林边缘的距离在 1939 年到 1980 年之间增加，这可能有利于内部特产物种的恢复。过渡分析表明，从农业保级的序列种植到牧场到老场以幼龄林到成熟林与个别地块的经济价值是一致的。大多数现代看台的年龄为 35-55 岁，位于斜坡上。只有 12.7% 的森林 > 120 岁。

结论

尽管森林覆盖率增加，林分分布与长期演替数据的比较表明，土地利用历史已将森林物种多样性集中在少数遗存林分中。生物多样性管理应侧重于识别和保护遗存林，而不是一般地保护二次生长的森林。