Impacts of Hurricane Michael on Urban Tree Canopy in Georgia

In October of 2018, Hurricane Michael, a category 5 hurricane, made landfall in Mexico Beach devastating Florida panhandle communities and surrounding areas like southwest Georgia with  strong winds, pounding rain, and inundating storm surge .

The hurricane not only caused loss of life and infrastructure but also major damage to the region's forests and urban trees. Trees throughout the world face many threats, but trees in an urban environment are especially vulnerable due to development, pests and diseases, poor planting conditions, and damage from cars, lawnmowers, and other manmade objects. Sea level rise and severe storms pose an even greater threat to forests located in coastal areas.

The Georgia Forestry Commission and Georgia Tree Council used federal hurricane relief funding to hire a Colorado-based trees and technology consulting firm,  PlanIT Geo , to measure the damage to the region's urban forest. With this information, GFC and GTC aim to assist communities with restoration of tree canopy and ensure that new trees are planted strategically and equitably across the landscape, with a focus on the hardest hit areas, historically underserved communities, and areas with the most viable planting space. A map of all trees and planting areas was created using pre- and post-storm aerial imagery to begin this effort. The damage was then totaled within affected communities and neighborhoods to begin to tell the story of Hurricane Michael's impacts on southwest Georgia's urban tree canopy.

Hurricane Michael was the first category 5 hurricane to make landfall in the continental U.S since Hurricane Andrew struck South Florida in 1992. Wind gusts up to  115 mph were recorded near Donalsonville  and up to 5" of rain fell in some areas. High wind speeds and subsequent "spinoff" tornados caused by the tropical storm produced widespread damage to the region, including its tree canopy. In fact, over 26 square miles of total tree canopy were found to have been lost due to the storm. That's almost half the land area of Albany, GA. With the information produced by this tree canopy assessment, the state and impacted communities now have the necessary tools to begin working towards recovering their valuable trees and community forests.

It is estimated that the strong winds and rain took down over 2,000,000 trees in Georgia's southwestern corner including forestland and agricultural timber, causing over  $300,000,000 in damages.  Local residents are now literally feeling the impacts of losing their tree canopy with reports of higher than normal temperatures and the threat of wildfires, flooding, and loss of wildlife habitat due to the downed trees. The map below shows pre-storm conditions in 2017 and post-storm conditions in 2019.

Ultimately Michael caused roughly $25 billion worth of damage in the United States. Although the hardest hit areas were in the Florida panhandle near the coast, the storm caused significant damage to inland areas as well. Some southwest Georgia counties, in particular, Dougherty, Baker, Miller, Decatur, Seminole, and Grady along with several others experienced the most severe winds of the storm. 22 cities within those counties were included in this assessment.

An urban tree canopy assessment typically consists of classifying aerial imagery as trees or other land cover types and summarizing that data over different scales such as cities, neighborhoods, or sometimes even individual parcels of land. This assessment also included locating ideal planting spaces and measuring changes in canopy cover between 2017 and 2019 in all studied locations.

With the increasing rate and severity of natural disasters, assessing damage and prioritizing equitable recovery efforts to restore urban forest conditions is more important than ever. Urban tree canopy assessments provide the data needed to help communities with these initiatives.

Hurricane Michael was the fourth strongest hurricane to ever hit the United States and the strongest to ever hit the Florida panhandle. With windspeeds at landfall over 160 mph, damage was widespread with disasters being declared by FEMA in many Georgia counties including Dougherty, Baker, Miller, Decatur, Seminole, Grady, and several others.

Rural cities like Baconton and Bainbridge experienced the most damage to their tree canopies. With hurricane force winds extending well inland, even cities up to 150+ miles from the Gulf of Mexico like Gordon had some loss of canopy. Throughout the 22 city study area, there was a combined loss of 2%, or over 1,700 acres, of the total tree canopy relative to the pre-storm conditions

The images and maps below illustrate the loss of canopy between 2017 (red) and 2019 (green) in each city. Large areas of red highlight heavily damaged areas. Additional information on canopy change and possible planting area is provided in the description. The slider maps represent 2017 on the left and 2019 on the right.

Areas where tree canopy was lost now represent prime areas for replanting. Each community in the study has at least 19% of its area designated as plantable space after the storm. A few even have up to 39%. Hurricane Michael left large voids of tree canopy cover, and residents in these areas are now feeling the impacts. It is important to not only plant in these areas, but also look at tree and environmental equity when planning tree planting efforts to ensure that all residents have access to the benefits that trees provide.

PlanIT Geo used the land cover data in addition to socio-economic data to enable the Georgia Forestry Commission and Georgia Tree Council to assist communities in prioritizing planting. Higher priority scores were given to areas with low canopy cover, large amounts of plantable space, greater amounts of storm damage or canopy loss, and lower income and more racially and ethnically diverse residents. Explore the maps below to see where the most suitable locations for planting are.

Areas that lost significant amounts of tree canopy also lost the benefits that those trees provided such as cleaner air quality, stormwater runoff mitigation, and carbon sequestration. Each city's pre- and post-storm benefits in U.S. dollars are shown below. These values were calculated using  i-Tree scientific research . In almost all cases, this value decreased after Hurricane Michael came through. In order to regain these benefits, planting efforts should start quickly as trees tend to provide increased benefits as they grow and mature.

It is vital for the communities that saw significant loss in tree canopy to prioritize planting to increase ecosystem service benefits. The data indicated that, within the study area (22 cities), tree canopy made up 46% of the area. 28% of the area is open, plantable space. The chart below summarizes the total current (2019) canopy and possible canopy percentages for each community within the study area.

In just one day, Hurricane Michael dramatically altered the community forests of southwest Georgia. More than three years later, we are still recovering and dealing with current storms, but there are now new tools and technology to understand the damage and help us recover our valuable urban tree canopy in a targeted way using data-informed decisions.

The Georgia Forestry Commission and Georgia Tree Council plan to use data from this study and work with communities to develop storm plans to keep citizens safe and protect valuable urban forest canopy in the event of a natural disaster. Learn more about the program and efforts to assist communities prepare for, respond to, and recover from major storm events.