Danieu Alana M, Ong Theresa W
Department of Environmental Studies; Ecology, Evolution, Environment & Society Graduate Program, Dartmouth College, Hanover, New Hampshire, United States.
PeerJ. 2025 May 9;13:e19420. doi: 10.7717/peerj.19420. eCollection 2025.
The northeastern United States experienced extensive deforestation for agriculture expansion and nearly equal passive reforestation following agriculture abandonment across the region over the past century. Old fields provide critical habitat as grasslands in the Northeast but tend to return to forests without intervention unless land managers implement disturbance regimes to maintain grassland states in the region. The relative importance of past and present disturbances in old field plant communities remains poorly resolved, partly because management varies widely in these systems. This motivated the present case study, which compares two proximate old fields that benefit from long and consistent management practices both before and after agriculture was abandoned in Hanover, NH. One field experienced agricultural disturbances associated with grazing while the other experienced cultivation each for 116 years followed by 50 years of the same annual mowing disturbances after agriculture was abandoned. Diversity was higher, communities more convergent across sub-plots, and woody individuals three times more numerous in the grazed site, while soil texture, type, elevation, and drainage had no discernible impact. The study helps to clarify the different legacies of grazing and cultivation on old field plant community diversity and composition. Despite undergoing 50 years of mowing following agriculture abandonment, the two old fields have divergent communities that are more consistent with the intensity of historic agricultural practices at each site than with any differences in measured soil characteristics. Understanding how agricultural legacies combine with contemporary disturbance regimes to shape successional communities may improve conservation and restoration efforts of grassland habitats and other ecosystems undergoing rapid environmental change, with implications for biodiversity, ecosystem services, and resilience.
在过去的一个世纪里，美国东北部为了农业扩张经历了大面积的森林砍伐，而在该地区农业废弃后，又出现了近乎等量的被动重新造林。旧耕地作为东北部的草原提供了关键栖息地，但如果没有干预，它们往往会恢复为森林，除非土地管理者实施干扰机制来维持该地区的草原状态。旧耕地植物群落中过去和当前干扰的相对重要性仍未得到很好的解决，部分原因是这些系统中的管理方式差异很大。这促使了本案例研究的开展，该研究比较了新罕布什尔州汉诺威的两块相邻的旧耕地，这两块地在农业废弃前后都受益于长期且一致的管理措施。一块地经历了与放牧相关的农业干扰，而另一块地则经历了116年的耕种，在农业废弃后又经历了50年相同的年度割草干扰。在放牧的地块中，多样性更高，群落跨子地块的趋同性更强，木本植物个体数量是另一地块的三倍，而土壤质地、类型、海拔和排水情况没有明显影响。该研究有助于阐明放牧和耕种对旧耕地植物群落多样性和组成的不同遗留影响。尽管在农业废弃后经历了50年的割草，但这两块旧耕地的群落不同，与每个地点历史农业实践的强度更一致，而不是与测量的土壤特征差异一致。了解农业遗留如何与当代干扰机制相结合来塑造演替群落，可能会改善草原栖息地和其他正在经历快速环境变化的生态系统的保护和恢复工作，对生物多样性、生态系统服务和恢复力具有重要意义。
