The role of fire in the earth's ecology

On the occasion of the earth Day a lecture under the title " The Role of Fire in the Earth's Ecology " was delivered on April 24th at the American Cultural center in Damascus, by Dr. Lytton Musselman, a professor of Biological Sciences and Director of the Herbarium at Old Dominion University in Norfolk, Virginia.

The lecture which was illustrated by slides intended to introduce the essential role of fire in the restoration and maintenance of pine forests. For example, some plants will not flower unless they are burned during the growing season; others have seeds stimulated to germinate by smoke.

Focusing on Pines and Fire, Dr. Musselman said that several species of the " genus Pinus " are adapted to fire, and considered mainly the longleaf pine, P. Palustris, with some references the most widespread pine in Syria, P. Brutia, from the stand point of the importance of fire in their life history.

He indicated two general types of fire adaptation are present in pines, noting that the most widespread is the production of cones which open in response to fire. He said that in these species " serotiny" is common.

He explained that fire adaptation at the seedling stage is much less frequent in pines. Certainly the best known example is longleaf pine, "Pinus Palustris," once a widespread species of the southeastern United States.. The long leaves on the seedling direct flames up and away from the tender terminal bud.

Based on these adaptations, the burning regime for management differs.

Pinus Brutia and P. Haleoensis usually require hotter fires which destroy the cone bearing trees. Such fires are at infrequent intervals.

In the case of these two Mediterranean pines, the interval is as much as twenty five years. It is debatable whether these species are obligately fire dependent, Dr. Musselman commented.

Out of his experience as a manager for the Black-water Ecological Preserve of Old Dominion University Dr. Musselman said that implementing a program of frequent ( fire return interval 3-5 years) prescribed fire at the Black-water Ecological Preserve will have the following impacts: Stimulate the diverse, fire- dependent herb layer ( increase herb cover and density); change the existing closed forest structure to Savanna or flat-woods structure; Reduce the dense hardwood and shrub members of Ericaceae in the midstory to improve wildlife habitat and herbaceous diversity; and over the long term, restore longleaf pine as the dominant canopy tree in sand-hill and flat-woods communities.

On the technique of fire adaptation by plants and Insects, Dr. Musselman said that recent research has discovered remarkable adaptations by both plants and animals to fire maintained communities. He explained that two plants, native to the Chaparral vegetation ( a Mediterranean ecosystem) of California are stimulated to germinate when exposed to smoke. The beetle, " Melanophila," has infrared detectors that can track a fire as distant as 75 Km.

Making a comparison with Mediterranean system, Dr. Musselman said that both P. Halepensis and P. Brutia respond to fire by releasing large numbers of seeds.. He noted that current research has not established if the relationship between fire and these pines is obligate. He continued that some components of the Mediterranean pine forest system, notable species of Cistus have seeds that are stimulated to germinate by fire.