The Pensacola area has had its fair share of rough weather lately. While the recent storms were not hurricanes, the rainfall totals rivaled many tropical storms, and the lighting and wind were disastrous. A tornado caused significant damage, including a tragic death, with more tumultuous weather in the forecast. Our rainy hurricane season has just begun, so it is worth talking about tree selection, management, and preparing for storms.
After the busy 1992, 1995, 1998, and 2004-05 hurricane seasons, several University of Florida researchers undertook an exhaustive on-the-ground project to look at tree damage statewide. Their goal was to determine which species survived high winds, and which trees were the most vulnerable during storms. Their findings were consistent, and have held up over the past few decades. A full description of the project can be found online, along with several publications that go over proper pruning and maintenance of trees, both before a storm and after recovery.
Live oaks have dense wood and are extremely wind-resistant species. Photo credit: Carrie Stevenson, UF IFAS Extension
This chart developed by UF researchers denotes the percentage of trees surviving Hurricane Ivan, by species. Courtesy M. Duryea and E. Kampf
Live oaks, and sand live oaks (which live on coastal sand dunes) are slow-growing trees with extraordinarily dense wood. This protects them in hurricane-force winds. Part of the working theory on why bald cypress, holly, and magnolia do well in storms is their pyramidal shape, which seems to allow wind to whip circularly around the trees and avoid damage. Sabal palms are botanically considered part of the grass category and not trees, so their single, flexible trunk allows them to handle the onslaught of wind. Sweetgums are particularly hardy in tornadoes, due to their sturdy root system and shorter, “stout” branches. Smaller understory trees like crape myrtle and dogwood are likely dodging the strongest winds, but also have strong branch structures and dense wood. These two species, along with sand live oak, also lost an average of more than 80% of their leaves. This defoliation is an adaptation to heavy winds, with trees that lost leaves performing better overall than species that held onto their leaves but toppled at the trunk.
Significant damage to a home after a tornado struck Pensacola in 2016. Photo credit: Carrie Stevenson, UF IFAS Extension
Another list of tree survivability was developed for residents in tropical and subtropical regions of the state. If you have friends or family in south-central Florida, be sure to share this information with them.
Besides planting wind-resistant species, the research team shared other observations related to tree planting and arrangement, too. Single trees are more vulnerable than trees planted in clusters, as they protect each other from incoming winds. Older trees, and those with preexisting damage, are more likely to fall. Trees with plenty of space around their roots do better—if a tree is surrounded on two or more sides with buildings or other hard surfaces, they cannot spread adequately. Detailed information on identifying damaged or poorly structured trees, along with maintenance and pruning tips, can be found in the “Urban Forest Hurricane Recovery Program” series of articles written by the UF tree specialists involved in the studies. The publications include good diagrams and photos of specific examples.
The Florida state wildflower, coreopsis, in bloom atop the Escambia County green roof. Photo credit: UF IFAS Extension
Most of us don’t think much about our roofs until there is a problem—a storm blows off shingles, causing a leak, necessitating a giant blue tarp to hold off the rain until we can get a contractor to replace the roof. But “a roof over your head” is one of those basic needs, perhaps only slightly less necessary for safety and survival than food and water.
Stormwater engineers and landscape architects have been thinking a lot about rooftops. Along with hard surfaces like roads and parking lots, roof area in a community is one of the biggest contributors of stormwater runoff. Those impervious surfaces don’t absorb any rainwater, contributing both to the volume and pollution potential of runoff from any given storm.
The skyline of downtown Kalamazoo, Michigan, as viewed from their City Hall green roof. Photo credit: Carrie Stevenson, UF IFAS Extension
While only applicable in specific situations, green roofs can provide a practical and beautiful solution to this problem. Escambia County has been home to the state’s largest green roof since 2009, housed atop the county’s Central Office Complex (COC). At over 33,000 square feet, it can absorb nearly 20,000 gallons of water during a rain, reducing flooding in a flood-prone area and allowing rain to soak into soil instead of becoming runoff. The COC roof was part of the building’s design from the beginning, but many commercial and government buildings have added green roofs as part of a retrofit. The rule of thumb is that if the building is sturdy enough to support an additional story, it can handle the weight of a green roof—including soil, vegetation, and water storage.
Last month, I visited the green roof atop Kalamazoo, Michigan’s City Hall. The imposing art deco building was constructed in the 1930’s, but the green roof on the building’s perimeter was added in 2011. Green roofs add tremendous environmental benefits but can be cost prohibitive, so many communities find grant funding (like the state of Florida’s Nonpoint Source Management grants) to help cover the expense. The Escambia County and Kalamazoo green roofs were both funded by grants. Besides the runoff reductions, a green roof can provide significant energy savings. Vegetation buffers a building from the incredibly hot summer rooftop temperatures, reducing the use of air conditioning and stabilizing indoor temperatures. This is the case for the Escambia County roof, in which an audit showed a 33% reduction in energy needs when compared to a conventionally designed building.
Green roofs can be built on flat-topped home roofs, and many European countries use them regularly. Plant selection for green roofs varies widely based on climate. Our local roof is mostly planted with beach dune species, while cooler, less humid regions make ample use of succulents like sedums. Low growing grasses and native wildflowers are great choices everywhere, providing color with limited maintenance.
One big goal of establishing a home lawn and landscape is to enjoy an attractive setting for family and friends, while also helping manage healthy soils and plants. Soil compaction at these sites can cause multiple problems for quality plants establishment and growth. Soil is an incredibly important resource creating the foundation for plants and water absorption.
Photo courtesy: Stephen Greer, UF IFAS
Soils are composed of many different things, including minerals. In Florida, these minerals often include sand of differing sizes and clay in the northern area of the counties in the panhandle of Florida. Soil is also composed of organic matter, nutrients, microorganisms and others. When soil compacts, the air spaces between the sand or clay are compressed, reducing the space between the mineral particles. This can occur anytime during the landscape and lawn construction phase or during long term maintenance of the area with equipment that could include tractors, mowers, and trucks.
What can be done to reduce soil compaction? There are steps that can be taken to help reduce this serious situation. Make a plan on how to best approach a given land area with the equipment needed to accomplish the landscape of your dreams. Where should heavy equipment travel and how much impact they will have to the soils, trees, and other plants already existing and others to be planted? At times heavy plywood may be needed to distribute the tire weight load over a larger area, reducing soil compaction by a tire directly on the soil. Once the big equipment use is complete, look at ways to reduce the areas that were compacted. Incorporating organic matter such as compost, pine bark, mulch, and others by tilling the soil and mixing it with the existing soil can help. Anytime the soil provides improved air space, root will better grow and penetrate larger areas of the soil and plants will be healthier.
Even light foot traffic over the same area over and over will slowly compact soils. Take a look at golf course at the end of cart paths or during a tournament with people walking over the same areas. The grass is damaged from the leaves at the surface to the roots below. Plugging these areas or possibly tilling and reestablishing these sites to reduce the compacted soils may be necessary.
Photo courtesy: Stephen Greer, UF IFAS
Water absorption is another area to plan for, as heavy rains do occur in Florida. Having landscapes and lawns that are properly managed allow increased water infiltration into the soil is critically important. Water runoff from the site is reduced or at least slowed to allow the nutrient from fertilizers used for the plant to have more time to be absorbed into the soil and taken up by the plants. This reduces the opportunity for nitrogen, phosphorus, and other nutrients to enter water areas such as ponds, creeks, lagoons, rivers and bays. Even if you are miles from an open water source, movement of water runoff can enter ditches and work their way to these open water areas, ultimately impacting drinking water, wildlife, and unwanted aquatic plant growth.
Plan ahead and talk with experts that can help with developing a plan. Contact your local Extension office for assistance!
Our Gardening in the Panhandle blogs cover many horticultural topics concerning yards, however let us not forget about properties that contain a body of water (pond, lake, retention or detention basin, stream, river or Gulf of Mexico). Out of the nine Florida-Friendly Landscaping™ principles, five directly deal with water quality. Those principles are #2 Water Efficiently, #3 Fertilize Appropriately, #6 Manage Yard Pests Responsibly, #8 Prevent Stormwater Runoff, and #9 Protect the Waterfront. An easy argument can be made that the remaining four principles (#1 Right Plant, Right Place, #4 Mulch, #5 Attract Wildlife, and #7 Recycle) can also impact water quality on your properties.
Photo Credit: University of Florida/IFAS Extension
The quickest and easiest way to start improving water quality is setting up a maintenance-free zone along your shore. At minimum, you should keep all chemicals 10′ away from the water’s edge and increase that distance as your slope becomes steeper. Chemicals include all fertilizers (#3) and any pesticides/herbicides (#6) meant for the landscape (there are times when situations arise where treatment of the water is warranted). If you must fertilize up slope, make sure to reduce irrigation (#2) to about 25% of normal the first time which keeps the fertilizer from dissolving and running down your slope’s surface (#9).
Cascades Park in Tallahassee, FL.
If possible replace turfgrass with a no mow zone containing plants adapted for shorelines to prevent applications of fertilizer and chemicals. Plants (#1) other than turfgrass will have deeper roots, stabilize the bank better and absorb more chemicals before entering the water. These taller plants in turn can become habitats (#5) for birds and other specimens which can increase your ecosystem’s biodiversity. Some properties have collection swales or low lying areas where water pools and then flows into the water. It is best to understand how water flows through the property and reduce chemicals in those areas too (#8).
Heavy rains caused water levels to raise around this pond and decomposing leaf litter added a film over the pond.
As gardeners, we tend to compost our leaves and yard debris (#7) plus use mulch (#4) to reduce water loss from our soils. Keep mulches and compost piles away from flood zones and when possible keep leaves from washing into your water as they can create films on the surface. Never allow grass clippings to land on water surfaces as they will add nutrients when tissue decays.
As Florida continues to grow, we all must play an important role in keeping our water clean and safe for us, animals, birds, and aquatic life. If you have questions on improving your water quality, please contact your local county Extension Agent or Water Regional Specialized Agent (RSA). For additional information visit these other sites.
Urban Fertilizer Ordinances in the Context of Environmental Horticulture and Water Quality Extension Programs: Frequently Asked Questions: https://edis.ifas.ufl.edu/publication/AE534
Stoke’s aster ‘Mel’s Blue’ 20 days after Hurricane Sally’s landfall. Notice how soil was washed away from root ball, all the leaves emerged post-hurricane. Photo credit: Mary Salinas, UF/IFAS Extension.
Hurricanes can wreak havoc in your landscape, but they can also reveal what plants are the toughest and most resilient. It’s a great learning opportunity.
A few weeks ago, Hurricane Sally came along and brought about 10 feet of surge and waves across my landscape and completely covered everything except the tallest trees for about 18 hours. (Fortunately, our house is on stilts and we did not have intrusion into our main living areas.)
As expected, the trees, including Dahoon Holly and Sweetbay Magnolia, took a beating but stayed intact. With their dense fibrous root system, most of the clumping native grasses also stayed put.
Perennial milkweed 3 weeks post-hurricane. New topsoil and compost now covers the rootball. Photo credit: Mary Salinas, UF/IFAS Extension.
The most surprising plant species that survived were about a dozen Stoke’s aster and 3 perennial milkweed. 4-5 inches of soil all around them was washed away, most of the roots were exposed, and the leaves were stripped or dead. The other perennials that had lived nearby were all washed away. To my surprise, within about 10 days after the storm, these two plant species started poking up new stems and leaves.
Here’s a list of some of the plants either in my yard or in the neighborhood that survived Hurricane Sally’s storm surge and may be suitable to add to your coastal landscape:
Dahoon holly, Ilex cassine
Muhly grass, Muhlenbergia capillaris
Dwarf Fakahatchee grass, Tripsacum floridanum
Perennial milkweed, Asclepias perennis
Stoke’s aster, Stokesia laevis, specifically the cultivars ‘Mel’s Blue’ and ‘Divinity’
Bottlebrush, Callistemon citrinus
Gardenia, Gardenia jasminoides
Bougainvillea, Bougainvillea spp.
Flax Lily, Dianella tasmanica
Crapemyrtle, Lagerstroemia spp.
Cabbage palm, Sabal palmetto
Canary Island date palm, Phoenix canariensis
Sweetbay magnolia, Magnolia virginiana
Augustinegrass, Stenotaphrum secundatum
And, unfortunately, the rhizomes of the invasive torpedograss also survived.
For more information on salt tolerant and hurricane resistant plants, see:
