Avian Biodiversity
Birds are a powerful indicator of ecosystem health. According to a team led by Dr. Ken Rosenburg at Cornell University’s Lab of Ornithology, North American bird populations have declined by nearly 3 billion over the last five decades - a decline they describe as a biodiversity crisis (1). In that study, forest birds represented the largest decline at 1.2 billion breeding adults lost. Yet, during that same period of staggering forest-guild avian decline, many traditional measurements suggest that North American forest ecosystems have improved dramatically. Part of these ecosystem improvements resulted from ecological forestry techniques responding to the habitat needs of specific bird species. For example, "mature-forest bird species" are designated as requiring mature forests with natural and largely undisturbed canopies. Conversely, "early-successional-forest bird species" need young forests that have been recently cut such that little to no canopy remains.
Given the large and growing proportion of mature forests in America, many forest-care groups are calling for the creation of young forests in the United States. The Wildlife Management Institute (WMI), for example, launched several programs including the Young Forest Initiative (YFI) which target to clear cut 11.2 million acres of forest in the Northeast and Upper Great Lake regions (2). The YFI is supported by many organizations including the USDA, US Forest Service, US Fish and Wildlife Service, Sustainable Forestry Initiative (SFI), and numerous state departments of natural resources (3). Recent studies, however, suggest that high-severity forest management can cause avian population declines (4). High-severity methods which hurt bird populations include clear cutting, but they also include forest thinning which retains many canopy trees but removes significant living biomass in order to increase the proportion of merchantable tree species in a forest (4).
Despite the decades of increasing mature forests in America to the high proportions today, mature forest bird species have still been declining. Increasing forest fragmentation has likely hurt avian populations. In addition, the generally low biodiversity of “mature forests” (see our graph in the old growth blog) will also suppress the flourishing of mature avian populations until forest conditions slowly progress toward healthy old growth levels. Given the suggested high biodiversity of Old Growth forests, perhaps the "mature" vs "young" habitat debate poses a false (or insufficient) dichotomy for forest care. Perhaps Old Growth forests, with their complex structure and extensive presence of Coarse Woody Debris (CWD) can support both mature- and young-forest avian guilds. Unfortunately, there are few true Old Growth ecosystems to confirm this hypothesis. That’s where Boone Road enters the conversation. Our Close-to-Nature Forestry (CTNF) research attempts to test this hypothesis by mimicking old growth characteristics. Similar CTNF research in Europe has already shown positive results and growing forest-bird population trends at landscape scales of thousands of square miles (5).
Since 2015, we have completed four timber harvests at our original research property in Tuscarawas County Ohio. Dividing that 100 plus acre forest into 16 management units, we measure canopy cover, biomass removals, logging damage, and numerous old growth metrics by management unit. We also measured avian species richness and abundance in a variety of management units to 1. Evaluate the CTNF impact on avian biodiversity, and 2. Assess the CTNF-managed biodiversity performance relative to the surrounding region of 571 square miles. Our results suggest that the CTNF habitats support a wide diversity of bird species (including both mature-forest and young-forest species). Additionally, the data suggests that CTNF habitats attracted double the percentage of bird species which are listed as high conservation concern by the North American Bird Conservation Initiative (NABCI) compared to the surrounding 571 square mile county. Our 2022 paper, authored by Dr. Jason Courter and James Gresh, was published by Avian Biology Research based in the UK (6).
Although North American forest ecosystems have improved dramatically over the last five decades, the biodiversity crisis implied by avian population declines should cause us to reflect on our current forest care path in the United States. North America understands the importance of biodiversity, but much of today’s forestry practices fundamentally remain unchanged relative to the last half century or more (7). At Boone Road Enterprises, we are challenging the forestry norms for our region by leveraging and adapting practices which were developed in Europe through deep scientific research. We recognize that our Ohio ecosystems may be different than Europe’s, but having visited forests in Europe in which CTNF has been practiced for over four decades and speaking with their CTNF experts, we believe CTNF is worth experimentation in Ohio.
Citations:
Rosenberg, K.V., A.M. Dokter, P.J. Blancher, J.R. Sauer, A.C. Smith, et al. 2019. Decline of the North American Avifauna. Science 366, no. 6461: 120–24. https://doi.org/10.1126/science.aaw1313.
Kellett, M.J., J.E. Maloof, S.A. Masino, L.E. Frelich, E.K. Faison, et al. 2023. Forest-clearing to create early-successional habitats: Questionable benefits, significant costs. Frontiers in Forests and Global Change. 5.1073677. doi: 10.3389/ffgc/2022/1073677.
Young Forest Initiative website. 2024. https://youngforest.org/partners
Betts MG, Yang Z, Hadley AS, Smith AC, Rousseau JS, et al. 2022. Forest Degradation Drives Widespread Avian Habitat and Population Declines. Nature Ecology & Evolution 6, no. 6: 709–19. https://doi.org/10.1038/s41559-022-01737-8
Schulze ED, Craven D, Durso AM, Reif J, Guderle M, et al. 2019. Positive Association between Forest Management, Environmental Change, and Forest Bird Abundance. For. Eco-syst., 1: 3. https://doi.org/10.1186/s40663-019-0160-8
Gresh, J.M., and J.R. Courter. 2022. Assessing the effects of Close-to-Nature Forestry on forest birds in the eastern United States: A case study and way forward. Avian Biology Research. Vol. 0(0) 1-12. DOI; 10.1177/17581559221121712
Puettmann KJ, Coates KD and Messier C. 2008. A Critique of Silviculture: Managing for Complexity. Washington, DC: Island Press, 27–28.