Consequences of habitat disturbance on seed fate of a Brazilian tropical dry forest tree Cavanillesia arborea (Malvaceae)

• Published in: Austral ecology 2015-09, Vol.40 (6), p.726-732
• Main Authors: Souza‐Silva, Herbert, Machado, Larissa F, Silva, Jhonathan O, Espírito‐Santo, Mário M
• Format: Article
• Language: English
• Subjects: deciduous forest; dry forests; forest trees; Forests; habitat alteration; habitat destruction; Habitats; Herbivores; Malvaceae; microclimate; mortality; natural regeneration; pastures; pioneer species; plant recruitment; predators; rodents; secondary succession; seed germination; seed mortality; seed predation; seed survival; seedlings; Seeds; species recruitment; Trees; viability
• ISSN: 1442-9985; 1442-9993
• DOI: 10.1111/aec.12241

We compared seed fate (survival, mortality by rodent predators, desiccation and other causes) of the tree Cavanillesia arborea (Malvaceae) in preserved old‐growth tropical dry forests and in nearby abandoned pasturelands in Brazil. For this purpose, we performed an experiment where 15 seeds were placed in the surroundings of 15 parental individuals in each habitat. These 450 seeds were monitored over four months. At the end of the experiment, seed predation by rodents was higher in forest (56.5%) than in pasture (8.9%) areas, but seed desiccation showed the opposite pattern (8.9% vs. 80.4%). Mortality by desiccation was also faster in pasture than in forest areas, probably reducing their attractiveness to predators in these areas. None of the seeds placed in the pasture survived, whereas 26.2% of seeds became seedlings in forest areas. The absence of seedling recruitment of Cavanillesia arborea in pastures is likely a consequence of their incapacity to tolerate the harsh abiotic conditions in this habitat. Thus, forest conversion imposes a strong limitation to the long‐term population viability of this species. However, restoration and natural regeneration of abandoned pastures can recreate the forest structure and microclimatic conditions favourable to seed germination and seedling establishment. Remnant individuals of Cavanillesia arborea in agricultural landscapes may have a negligible contribution to current recruitment, but they can attract potential dispersers of pioneer species, with positive feedbacks to future recruitment during secondary succession.