Trees are dying left and right this summer. Sprawling canopies of huge oaks turn brown almost overnight. Cypress trees redden and lose leaves months early.
The trees are hard to miss, and arborists, tree services and the Volusia County Cooperative Extension Service say they're fielding "tons of calls."
It even happened to the extension director, David Griffis. "We're eating dinner and I hear this crash," he said. "I look out my backyard and a perfectly good oak tree just fell."
It's not just here. Tree deaths are above normal across a good portion of the state this year, said Ed Barnard, a forest pathologist with the Florida Division of Forestry in Gainesville.
The good news is it's not the dreaded sudden oak death or oak wilt that experts fear will be found in Florida and lay waste to trees as they have in other states.
"We have no evidence to date that we are seeing any kind of epidemic or outbreak," Barnard said. "All of our tests are negative."
It's actually a typical summer problem that's worse this year, blamed on the same things that have disrupted so much in the past couple of years -- hurricanes, high water and drought.
A tree can have problems not visible to the untrained eye. Like prettily painted toenails that hide the grossest fungus, a leafy top may hide rotting roots. Even though it seems like trees died suddenly, they may have been sick for months -- or under attack.
Weakened trees are more susceptible to bugs, root disease, fungus and other diseases, said Barnard, who has been at the Division of Forestry for 28 years. "We've seen these kinds of scenarios repeatedly in the past, not necessarily as dramatic as this year," he said.
The problems probably started during the hurricanes of 2004, as trees were whipped and twisted by the fierce winds, or even during the extreme drought earlier in the decade. The high water that followed the hurricanes killed other trees.
This year's spring drought was the final blow. After casually surveying county foresters around the state, Barnard said he was told the majority of the victims this year are laurel and water oaks. Those oaks are more vulnerable to Mother Nature's whims than their cousins, the live oaks.
The tree Griffis lost was a laurel oak, probably diseased in places he couldn't see -- inside the trunk or at the roots, he said. It may even have died of old age. Their life spans are shorter than live oaks.
The fluctuating water levels have been a big problem, for the oaks as well as other trees. Either extreme can be bad.
The high, standing water left after fall 2004 is responsible for the deaths of many trees, for example many of the trees in Tiger Bay State Forest, on either side of U.S. 92 between DeLand and Daytona Beach.
The water deprives the roots of oxygen. That kills the roots and prevents them from taking food and water to the tree. A similar phenomenon occurs when dirt and mulch get piled up around the base of the tree. A tree can literally suffocate even though all the rest of it is exposed to air. Conversely, a dearth of water can also kill trees.
It puts "extra pressure on the trees and they can't adapt," said arborist Don Spence, owner of Native Florida Landscapes. The trees' large spreading canopies can lead to their own demise. The leaves use up more water than the roots can provide.
Bugs are to blame for the cypress tree problems. They're losing their leaves thanks to a cypress leaf beetle, Division of Forestry entomologist Bud Mayfield said. The beetles come and go, wreaking worse damage in some years. The bugs nibble on the little leaflets of cypress trees, then the leaves begin to dehydrate and turn brown.
Another common cause of dead trees is nearby construction, which damages roots and prevents trees from getting water, said Chuck Lippi, a retired Flagler County extension director and arborist on a Palm Coast committee writing a tree ordinance.
Others say larger societal problems are also to blame, such as growth, pollution and global warming. In Florida, tree experts and hydrologists have found that overpumping water can drop water levels severely enough to kill trees and damage wetland habitats.
One agency looking into that locally is the St. Johns River Water Management District. District officials have documented trees dying in wetlands near city well fields. It's not something the district actively monitors, but it's one reason the agency is trying to steer utilities in Volusia County toward alternative sources of water, said Dr. Sonny Hall, a technical program manager for the district.
The tree experts also have a couple of hurricane-related theories they'd like to explore.
One theory is the trees may have been damaged when the winds blew all their leaves off. New leaf growth would draw on the carbohydrate reserves in the trees' stems and roots. And that's like humans using up extra fat, Barnard said. That in turn weakens a tree's ability to withstand infection by pests and pestilence.
"It's a believable scenario," Barnard said, "but it's not proven and we don't have data."
Another theory is that the hurricane winds caused internal damage to the trees' circulatory systems, Barnard said, kind of like the problems humans have with clogged arteries.
"We don't really know what happens mechanically inside those trees that are whipped around," Barnard said. "It's conceivable to have cellular and anatomical damage that interferes with the uptake of water and transpiration."
That's Alan Long's theory. The University of Florida forestry professor lives on two acres in Glenwood near DeLand and lost several long-leaf pines and laurel oaks this summer.
He surmises that during the hurricanes wood in the center of the trees might have been split or the roots might have broken off.
"When you have a break in the plumbing system, long dry spells just kind of push them over the edge."Daytona Beach News Journal Online
