Changes in the floristic composition of a Quercus coccifera L. garrigue in relation to different fire regimes

Published source details Trabaud L. & (1981) Changes in the floristic composition of a Quercus coccifera L. garrigue in relation to different fire regimes. Vegetatio (now Plant Ecology), 105-116.
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Summary

Mediterranean maquis and garigue habitats are typically maintained through a combination of pastrol grazing and periodic fires which prevents the sucession to woodland. An experiment was undertaken in an area of Kermes oak Quercus coccifera garrigue in southeast France. The objectives of the study were to follow the changes of the vegetation in response to different prescribed burning regimes: a fire every six years, a fire every three years and a fire every two years, with burns at the end of spring or beginning of autumn.

Study area: The experiment was undertaken on Puech-du-Mas-du-Juge, a hill about 10 km N of the city of Montpellier, southeast France. The vegetation is a kermes oak Quercus coccifera scrub garrigue community typical of that which covers large areas of southern France.

Burn treatments: The burn times were chosen in relation to the growth stage of the kermes oak:

Late spring - oak has started spring growth; the first annual shoots and young leaves have developed; flowers have appeared. Burns are usually undertaken at the end of May or the beginning of June, according to weather conditions.

Early autumn - after the lignification of young twigs when the vegetation appears dormant; burns were undertaken at the beginning of September.

Burn frequencies were: one fire every six years; one fire every three years; and one fire every two years; each undertaken in spring or autumn. Control plots were left unburned. There were five replicates of each, thus giving a total of 35 plots (plot size is nor given in the original paper).

Vegetation monitoring: From 1969 to 1975, a list of all the taxa present and their frequency in each plot was made every year in May, before the spring burns, and four months after burns.

Four months after burning, whatever the season, plant species richness in all plots was lower than before the fire. Generally, after more than four months, autumn burnt plots had a higher number of species than those burnt in spring. This may be attributable to the active spring growth of Kermes oak leaving little open space for other taxa to establish, arter a burn. In contrast, in autumn when oak growth may be negligible and thus it does not re-occupy areas opened up by burning so rapidly, this permits other taxa to establish and, sometimes to germinate the following spring.

Under all burn regimes, the main floristic composition remained constant with characteristic dominant taxa persisting. This relative stability may explained by the fact that most of the taxa present before burning regenerate principally by vegetative means (mostly resprouting). Annual species appearing during the year after each burn were rapidly lost due to competition by longer-lived plants already present before the fires.

Note: If using or referring to this published study, please read and quote the original paper, this can be viewed at:

http://springerlink.metapress.com/content/n335m637q31p1u72/fulltext.pdf