Extended Abstract (908K)5C.9
Spatial distribution of the potential effects of wildfires under the intermediate disturbance hypothesis in a Mexican forest ecosystem
J. German Flores G., Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias, Guadalajara, Jalisco, Mexico
This paper present one of the first attempts to define the spatial distribution of the effects of wildfires under the intermediate disturbance hypothesis in a Mexican forest ecosystem. Although fire is one of the most important factors of disturbance on a forest ecosystem, not all fires have the same effect. The level of disturbance of a fire is related to its intensity and frequency. For instance, very frequent fires are, in general, of low intensity, while a fire of low frequency is, in general, of high intensity. In the second case the result is a great damage of the forest ecosystem (structure and functionality).While in the first case, in general the damage is low, and rather we could have a lot of beneficial effects. Such as the establishment of regeneration, increase of biodiversity, etc. Based on the above mentioned, we could have three general conditions in a forest: a) Not disturbed forest; b) Intermediate disturbed forest (high frequency and low intensity fire); and C) High disturbed forest (low frequency and high intensity fire). According to the Intermediate Disturbance Hypothesis we can find a bigger number of species, or conditions, in an area that has been perturbed by a fire of high frequency and low intensity, which represents a intermediate disturb. According to some works on fire ecology this hypothesis is true. In the case of a forest disturbed by a high intensity fire, this could be obvious. However in the case of a not disturbed condition an explanations is necessary. When a forest ecosystem has not be affected by a fire, within a considerable period, few species start to dominate the ecosystems, which could affect not only the number of individuals per species, but also the number of species (with the corresponding alteration of the ecosystem processes). In general such dominant species do not tolerate fire very well, therefore the occurrence of fire avoid their increment. The result of this is a lower competence among species, and specific conditions (fertility, light, and space) for certain species.
Session 5C, FIRE HISTORY/FIRE REGIMES: Part 2 (Track III)
Thursday, 20 November 2003, 8:00 AM-2:30 PM
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