Understanding Tree Canopy Cover and Its Role in Urban Forest Conservation

Presentation given at the 18th Annual EcoSavvy Symposium hosted by Fairfax County Master Gardeners.

Transcript

1. Understanding Tree Canopy Cover and Its Role in Urban Forest Conservation P. Eric Wiseman, PhD Associate Professor of Urban and Community Forestry Dept. of Forest Resources and Environmental Conservation Virginia Tech vtuf@vt.edu linktr.ee/EricWiseman @vtarborist Source: www.dronegenuity.com/aerial-photography/virginia/ The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022
2. Presentation Outline 02  37 o What is tree canopy cover and why is it important to urban environments? o What do we know about tree canopy cover in urban areas of Virginia? o What are threats and challenges to sustaining tree canopy cover in urban areas? o How can we measure and monitor tree canopy cover in urban areas? o What are key strategies for conserving tree canopy cover in urban areas? The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022
3. The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 Urban Forests and Why They Matter 03  37
4. Urban Forests and Why They Matter Source: www.oufc.org/2021/06/05/announcing-2020-tree-cities-of-the-world Trees and associated natural resources found in and around an area of dense human development Source: www.whiterockcity.ca/484/Urban-Forest-Management-Plan The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 04  37
5. Urban Forests and Why They Matter Community cohesion Source: ourauckland.aucklandcouncil.govt.nz/news/2019/03/knowing- growing-and-protecting-a-flourishing-urban-forest-for-auckland/ The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 05  37
6. Urban Forests and Why They Matter • Overall, there are an estimated 5.5 billion trees in US urban areas, which equates to 22.2 trees per capita. • In US cities, about 1 in 3 trees have been planted. • Planting accounts for the majority of trees in residential (75%) and commercial (61%) areas. • Natural regeneration on vacant lands is a major contributor to tree cover in the forest ecoregion. Source: Nowak, D. J., & Greenfield, E. J. (2018). US urban forest statistics, values, and projections. Journal of Forestry, 116(2), 164-177. The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 06  37
7. The layer of tree foliage, branches, and stems that overhangs the ground when viewed from above Source: www.google.com/earth • Foliage is the key component of canopy because it provides most of the surface area for shade, interception, and absorption • We usually think of tree canopy as 2-D, but keep in mind that it is actually 3-D • Tree canopy is dynamic in both space and time due to regeneration, growth, mortality, and land use change The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 What Is Tree Canopy Cover? 07  37
8. The most basic measure of tree canopy cover is the percentage of the total land area covered by canopy Source: Plan-It Geo, Urban Tree Canopy Assessments Source: Plan-It Geo, Urban Tree Canopy Assessments 35% 10% 30% 5% 10% 5% 0% 0% 0% 5% The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 What Is Tree Canopy Cover? 08  37
9. Source: www.thoughtco.com/where-us-forests-are-located-1343035 Source: Nowak, D.J., et al. (2010). US Forest Service GTR NRS-62. Forest Cover Urban Tree Canopy Cover The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 What Is Tree Canopy Cover? 09  37
10. Data Source: Nowak, D. J., & Greenfield, E. J. (2018). Declining urban and community tree cover in the United States. Urban Forestry & Urban Greening, 32, 32-55. Chart Source: www.deeproot.com/blog/blog- entries/the-latest-urban-tree-canopy-cover-by-state National UTC Average (2014): 39.4% The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 What Is Tree Canopy Cover? 10  37
11. Source: Nowak, D. J., & Greenfield, E. J. (2012). Tree and impervious cover in the United States. Landscape and Urban Planning, 107(1), 21-30. Although tree cover accounts for 66% of VA’s land cover, urban tree cover only accounts for 6% of total tree cover. VA urban tree cover circa 2014 averaged 45.2%. This equates to about 772 thousand acres of urban tree cover and 166 million urban trees. Source: coopercenterdemographics.files.wordpress.com/2014/03/current.jpg The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 What Is Tree Canopy Cover? 11  37
12. Remote Sensing: Analysis of imagery and LiDAR acquired by sensors from above How Is Tree Canopy Cover Assessed? The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 12  37
13. The Process: Computerized Image Analysis and Land Cover Classification Hyperspectral Image: Red, Green, Blue Infrared LiDAR Land Cover Map Source: vtcommunityforestry.org/resources/inventories-management-plans/tree-canopy-assessments How Is Tree Canopy Cover Assessed? The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 13  37
14. The Product: Data describing canopy amount, distribution, and ownership Source: www.charlottesville.gov/Archive/ViewFile/Item/97 How Is Tree Canopy Cover Assessed? The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 14  37
15. It’s a straight-forward concept and metric for allied professionals and the general public to understand • Tree canopy is strongly linked to urban ecosystem function and human well-being • Tree canopy cover can be efficiently quantified and characterized over large geographic areas with high spatial resolution • Tree canopy cover data can be utilized in land use planning and environmental policy The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 Why Do We Emphasize Tree Canopy Cover? 15  37
16. DIRECT THREATS INDIRECT THREATS o Forest Land Conversion (sprawl) o Urban Infill Development (density) o Lack of Green Infrastructure Plan o Improper Greenspace Design o Limited Management Resources o Inadequate Tree Protection BMPs o Lack of Re-Planting Trees o Climate Change o Invasive Pests and Plants o Urban Stress Factors - Heat and Drought - Degraded Soil - Pollution & Disturbance Source: stock.adobe.com/search/images?k=land+development&asset_id=225938293 The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 What Are Threats to Tree Canopy Cover? 16  37
17. Percentage Change in Urban Land Use, 1997 to 2060 30 to 43 million acres of land in the South Source: www.srs.fs.usda.gov/compass/2014/10/09/projected-land-use-change-in-the-south The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 What Are Threats to Tree Canopy Cover? 17  37
18. The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 Source: vanhde.org/content/map What Are Threats to Tree Canopy Cover? 18  37
19. Source: vanhde.org/content/map The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 What Are Threats to Tree Canopy Cover? 19  37
20. The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 What Are Threats to Tree Canopy Cover? Source: www.mrlc.gov/viewer 20  37
21. The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 What Are Threats to Tree Canopy Cover? Source: www.mrlc.gov/viewer 21  37
22. The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 What Are Threats to Tree Canopy Cover? Source: www.mrlc.gov/viewer 22  37
23. The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 What Are Threats to Tree Canopy Cover? 23  37
24. Year 2009 to 2014 Tree cover in US urban areas declined at rate of 138,000 acres annually, about 28 million trees per year Lost $96 million in annual ecosystem services Virginia lost 4,270 acres of urban tree cover annually, about 878 thousand trees per year, and $2.5 million in annual ecosystem services Source: Nowak, D. J., & Greenfield, E. J. (2018). Declining urban and community tree cover in the United States. Urban forestry & Urban Greening, 32, 32-55. The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 What Are Threats to Tree Canopy Cover? 24  37
25. The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 What Are Threats to Tree Canopy Cover? Source: www.ajc.com/neighborhoods/dekalb Source: saportareport.com 25  37
26. The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 What Are Threats to Tree Canopy Cover? Source: www.cbf.org/news-media/newsroom/2022/virginia Source: lis.virginia.gov/cgi-bin/legp604.exe?ses=221&typ=bil&val=sb537 26  37
27. Source: stevekingonsustainability.blogspot.com, March 10 2013 Space for large-maturing, long-lived, healthy trees? The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 What Are Threats to Tree Canopy Cover? 27  37
28. The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 What Are Threats to Tree Canopy Cover? 28  37
29. The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 What Are Threats to Tree Canopy Cover? Source: www.bloomberg.com/news/features/2021-07-30/what-happens-after-pledges-to-plant-millions-of-trees Source: www.fs.fed.us/psw/topics/urban_forestry/products/cufr_511_large_tree_argument.pdf 29  37
30. Mission: To promote the care and appreciation of trees – big and small Document the largest specimens in the state and provide resources to aid in their protection and care Maclura pomifera** Charlotte Co. 65’ 93’ 328” 416 pts. Photo credit: A. Cassell The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 The Virginia Big Tree Program 30  37
31. The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 The Virginia Big Tree Program 31  37
32. Quercus pagoda** City of Portsmouth 114’ height 138’ crown spread 331” trunk girth 480 pts. o Register comprises a searchable online database plus an historical record archive o Currently curate the top-three* specimens of any native or non-native tree species (and verifiable sub-species and varieties) o Minimum eligible tree size: ≥ 13’ height and ≥ 9.5” trunk circumference o Trees must be re-certified every ten years to remain active in the register The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 The Virginia Big Tree Program 32  37
33. o 116 counties and independent cities have 1 or more big trees in the register o Currently 1,539 living specimens across 474 species are curated in the register o Currently 91 national champs/co-champs, top-3 most champs in country *not all trees shown due to privacy policy The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 The Virginia Big Tree Program 33  37
34. CONSERVE EXISTING COVER “Take care of what you’ve got!” REPLENISH NEW COVER “Plant trees!” Intrinsic Motivations Property Value Commerce Health & Well-Being Educate People About: Consequences of Loss Extrinsic Motivations Zoning Ordinances Resource Protection Areas Conservation Easements Financial Inducements How Do We Sustain Tree Canopy Cover? The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 34  37
35. Community Industry Government Scientists Professionals o Urban forests require space o Urban forests require funding o Urban forests require monitoring o Urban forests require advocates o Urban forests require planning o Urban forests require expertise But It Is Not That Simple… The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 35  37
36. Municipal Non-Profit Residential Commercial Framework for Stewardship Investment in Stewardship Space for Stewardship Advocacy for Stewardship Partnerships For Sustaining Tree Canopy The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 36  37
37. Take Home Messages o Tree canopy cover is strongly correlated to benefits of the urban forest o Livability and sustainability of urban areas depends on conservation and management of tree canopy cover o Land development without careful consideration for protecting and replenishing trees is a primary cause of canopy loss o Tree canopy stewardship requires commitment, partnership, and action by multiple stakeholder groups The 18th Annual EcoSavvy Symposium • Alexandria, VA • February 19, 2022 37  37