A forest in transformation


Published: Friday, January 17, 2003 at 6:01 a.m.
Last Modified: Friday, January 17, 2003 at 1:16 a.m.

People in Gainesville and Alachua County love trees. We faithfully treasure the huge old monarchs of the urban forest, even though their roots occasionally lift sidewalks and disrupt utility lines.

Saplings planted to provide future canopy evince a community serious about the "park" in "parking lot."

Through the "Tree-mendous Gainesville" program, 1,000 young trees are planted annually to beautify public property and to enhance the sustainability of our community.

Gainesville is still the only local government in the nation with a "Tree Appeals Board" to review decisions to remove regulated trees from public land. In the private sector, trees are frequent features in the advertising and logos of local businesses.

In Gainesville, our connection to trees is acknowledged on Arbor Day as we affirm their value to our quality of life. However, 2003 brings an Arbor Day with unprecedented numbers of dead trees in the urban forest.

The most recent southern pine beetle (SPB) epidemic killed about 9,000 pines in the Gainesville urban area. While many residents responded to the call for fast action and removed infested pines before the epidemic could spread to their neighbors, some did nothing.

Their dead pines stand as ominous reminders that SPB infestation is always fatal. After several of these crashed into transformers and pulled down utility lines, GRU spent an unexpected $150,000 on removals.

In addition to dead pines, many trees of weak species also stand lifeless. As such, they provide essential nesting cavities for birds and small mammals, insects for birds to eat, and strata for some delicious edible mushrooms.

However, location is everything, and if a dead tree's probable direction of fall could harm people or property, it should be removed.

All dead trees disintegrate. Some, like live oak and hickory, decay very slowly. Others like laurel oaks, water oaks and loblolly pines rot quickly. The latter three, whether alive or dead, are the species that most often fall unexpectedly into the road, onto cars, homes, or utility lines.

An important factor in the tree death evident this Arbor Day is diminished rainfall. The average precipitation for the past 25 years is 10 percent less than the averages for the prior two 25-year periods. Trees in habitats where survival requirements were met marginally are perishing.

Forests of large Water Oaks near Evergreen Cemetery that had grown up quickly on abandoned agricultural fields survived while the water table was at normal levels, but during the past year have died in large numbers.

The short-term view of all these dead trees tends to be alarm. However, a longer perspective suggests the situation is more like spring cleaning. The death of weak trees creates places for stronger species and eventually leads to the transformation of the urban forest.

Regarding natural forests, extirpation and introduction are key concepts. Local elimination of a dominant tree from an ecosystem can contribute to the extinction of other species.

Extirpation of longleaf pines through logging threatens the viability of the red-cockaded woodpecker because they mostly nest in tall pines (80 years or older).

Ironically, concern for diminishing woodpecker populations sometimes motivates landowners to hasten the extirpation of longleafs from their property because they fear government will limit their right to derive income they have counted on.

Wherever there is a void created in an ecosystem, something fills it. Exotic species often have a strong competitive advantage in colonizing openings created by tree demise.

Tallows introduced from Asia, for example, out-compete native red maples, fringe trees, and bays in Florida wetlands. The associated microorganisms and insects that naturally limit tallows are absent here. The resulting tallow monoculture ends up destroying the ecological balance, as toxins leaching from the leaves poison the invertebrate life on which fish populations depend.

Extirpation and introduction figure in the management of Gainesville's trees as we look for the opportunity to transform the canopy into a diverse, sustainable, and durable urban forest.

Widespread SPB-induced loblolly pine death has been bad for property owners, but if these weaker trees are replaced with stronger species, the net result will be very beneficial.

The city and environmentally concerned property owners have been planting longleaf pines as replacements where pines are desirable. Not only are they more durable and longer-lived, the longleafs foster the hope that perhaps woodpecker clans may again live in Alachua County.

Laurel oak, water oak, loblolly pine, sweetgum, camphor or tallow were lost from Gainesville's streets and parks last year in greater numbers than ever before.

Their deaths provide the opportunity to plant native species currently under-represented in the urban forest: bluff, basket, myrtle and chapman oaks; winged, Florida, and water elms; white, green, and pop ash; tupelo; mockernut hickory; spruce and longleaf pines, etc.

Arbor Day in this community that loves trees is widely celebrated. Garden clubs, schools and civic groups plant trees each year.

The communitywide event hosted annually by the City Beautification Board occurs at noon today in Cedar Grove Park east of Waldo Road on NE 14th Avenue.

Cedar Grove is one of Gainesville's newest public spaces.

The celebration will culminate with the planting of a shumard oak grown in the city's tree farm and transplanted with a tree spade.

The shumard is one of 38 trees (including cedars) to commemorate this Arbor Day.

Meg Niederhofer is arborist for the city of Gainesville and can be contacted at Arborist@ci.gainesville.fl.us or 334-2171.

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