Distribution and regeneration of Acacia pennatula (Schltdl & Cham) Benth in disturbed forests in northern Chiapas, Mexico
Montane rain forest in Chiapas (Mexico) has been disturbed by human actions since pre-Columbian times. In recent years, this disturbance regime has undergone a marked change in nature, spatial extent, severity and recurrence time. This has led to notable shifts in the composition of remaining areas of woody vegetation. The distribution of Acacia pennatula has increased as a consequence of the expansion of cattle grazing into areas previously covered by closed montane forest. In order to describe this process we determined the size class distribution of A. pennatula in five-forest types differing both in canopy cover and intensity of disturbance by grazing. The role of cattle in the germination of A. pennatula seeds was evaluated in greenhouse experiments. The potential of A. pennatula to facilitate the natural establishment of seedlings of woody species was assessed in the field. Populations of A. pennatula were found to be largely composed of seedlings and juveniles. Some larger individuals were found in sites with a long prior history of disturbance. We recorded important differences in the percentage of photosynthetic active radiation, herbaceous cover and soil compaction between open and shaded habitats. Germination of seeds of A. pennatula occurred more rapidly under shade than in sunlight. Our experimental evidence suggested ingestion by cattle could decrease the probability of germination of individual seeds. The role of cattle as dispersal agents and their effect on long-term population dynamics requires further investigation. Our observations suggest that the canopy cover provided by A. pennatula produces a favourable environment for the establishment of woody species being lost elsewhere. We discuss the potential of A. pennatula as a facilitator species for the restoration of degraded montane forests.
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| Format: | biblioteca |
| Published: |
2002
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| Subjects: | ACACIA PENDULA, ACACIA, CUBIERTA DE COPAS, AGRICULTURA, PASTOREO, FOTOSINTESIS, DINAMICA DE POBLACIONES, BOSQUE HUMEDO, GERMINACION, SEMILLAS, SOMBRA, SUELO, TIPOS DE SUELOS, DISEMINACION DE SEMILLAS, MEXICO, CHIAPAS, AMERICA DEL NORTE, |
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| Summary: | Montane rain forest in Chiapas (Mexico) has been disturbed by human actions since pre-Columbian times. In recent years, this disturbance regime has undergone a marked change in nature, spatial extent, severity and recurrence time. This has led to notable shifts in the composition of remaining areas of woody vegetation. The distribution of Acacia pennatula has increased as a consequence of the expansion of cattle grazing into areas previously covered by closed montane forest. In order to describe this process we determined the size class distribution of A. pennatula in five-forest types differing both in canopy cover and intensity of disturbance by grazing. The role of cattle in the germination of A. pennatula seeds was evaluated in greenhouse experiments. The potential of A. pennatula to facilitate the natural establishment of seedlings of woody species was assessed in the field. Populations of A. pennatula were found to be largely composed of seedlings and juveniles. Some larger individuals were found in sites with a long prior history of disturbance. We recorded important differences in the percentage of photosynthetic active radiation, herbaceous cover and soil compaction between open and shaded habitats. Germination of seeds of A. pennatula occurred more rapidly under shade than in sunlight. Our experimental evidence suggested ingestion by cattle could decrease the probability of germination of individual seeds. The role of cattle as dispersal agents and their effect on long-term population dynamics requires further investigation. Our observations suggest that the canopy cover provided by A. pennatula produces a favourable environment for the establishment of woody species being lost elsewhere. We discuss the potential of A. pennatula as a facilitator species for the restoration of degraded montane forests. |
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