Department of Entomology and Wildlife Ecology, University of Delaware, Newark, Delaware, United States of America.
Tall Timbers Research Station, Tallahassee, Florida, United States of America.
PLoS One. 2024 Jun 20;19(6):e0302040. doi: 10.1371/journal.pone.0302040. eCollection 2024.
Fire suppression has negatively impacted thousands of acres of private and public lands in the United States. As a case study, the New Jersey Pine Barrens (NJPB) are a disturbance driven ecosystem that is experiencing serious ecological implications due to a loss of traditional forest thinning activities such as harvesting for forest products or thinning for wildfire fuel-load reduction measures coupled with a long-standing philosophy of fire suppression and dormant-season prescribed burning. Dense closed-canopy forest conditions, dissimilar to historic open-canopy forests of the NJPB, have reduced abundance and diversity of certain flora and fauna, including regionally imperiled breeding birds. In recent years, active forest stewardship (e.g., thinning, clear-cutting, and burning) has occurred on private and some public lands within the NJPB; however, the impact of such management on breeding birds is unclear due to a paucity of research on this subject within the NJPB. During 2012, 2013, 2016, and 2017, we conducted repeat-visit point counts (n = 1,800) for breeding songbirds across 75 control and 75 treatment sites within the NJPB to assess the influence of forest structure at three strata levels (groundcover, midstory profile, and canopy) on breeding bird communities. Specifically, we constructed a hierarchical community abundance model within a Bayesian framework for Bird Conservation Region (BCR) 30 priority upland birds (n = 12) within three species suites: Forested Upland, Scrub-Shrub (or Young Forest), and Grassland. At the community level, we found a negative relationship between bird abundance and live tree basal area. At the BCR 30 suite level, we found no relationship between Forested Upland suite-level abundance and any of the measured covariates; however, we found a negative relationship between percentage of woody groundcover and Scrub-Shrub suite-level abundance, and negative relationship between horizontal visual obstruction at 2 m above ground level and Grassland suite-level abundance. Furthermore, the two latter species suites exhibited a strong negative relationship with basal area. We recommend active forest stewardship that specifically targets opening the canopy to achieve basal areas between ~0-15 m2/ha via selective thinning, shelter cutting, and small-scale clear cutting. Mechanical treatment and prescribed burning would produce such conditions and have the added benefit of reducing fuel loads across this ~4,500 km2 landscape as well as assisting in carbon defense strategies for the region.
在美国，灭火行动对数千英亩的私人和公共土地产生了负面影响。作为一个案例研究，新泽西州松林地（NJPB）是一个受干扰的生态系统，由于传统的森林抚育活动（如为森林产品采伐或为减少野火燃料负荷而进行的疏伐）的减少，以及长期以来的灭火和休眠季节规定性燃烧的理念，该系统正面临严重的生态影响。茂密的封闭树冠条件与 NJPB 的历史开阔林冠条件不同，减少了某些动植物的数量和多样性，包括该地区受到威胁的繁殖鸟类。近年来，在 NJPB 的私人和一些公共土地上已经进行了积极的森林管理（例如疏伐、皆伐和燃烧）；然而，由于该地区缺乏关于这一主题的研究，因此这种管理对繁殖鸟类的影响尚不清楚。在 2012 年、2013 年、2016 年和 2017 年，我们在 NJPB 内的 75 个对照点和 75 个处理点进行了重复访问点计数（n = 1,800），以评估三个层次（地被层、中景轮廓和树冠）的森林结构对繁殖鸟类群落的影响。具体来说，我们在贝叶斯框架内为鸟类保护区（BCR）30 种优先高地鸟类（n = 12）构建了一个分层社区丰度模型，分为三个物种套件：森林高地、灌丛-灌木（或幼林）和草地。在群落水平上，我们发现鸟类丰度与活树基面积之间存在负相关关系。在 BCR 30 套件水平上，我们发现森林高地套件水平丰度与任何测量的协变量之间没有关系；然而，我们发现木质地被物百分比与灌丛-灌木套件水平丰度之间存在负相关关系，以及地面以上 2 米处的水平视觉障碍物与草地套件水平丰度之间存在负相关关系。此外，后两个物种套件与基面积之间存在很强的负相关关系。我们建议进行积极的森林管理，通过选择性疏伐、遮蔽砍伐和小规模皆伐，专门将树冠打开，达到 0-15 m2/ha 的基面积。机械处理和规定性燃烧将产生这种条件，并有助于减少该 4500 平方公里景观的燃料负荷，并协助该地区的碳防御策略。
