Regeneration of dry forest species Population dynamics and spatial distribution of seedlings and saplings of four dry forest species in Nicaragua

The temporal variation in seedling and sapling densities of four dry forest species, Calycophyllum candidissimum, Cedrela odorata, Haematoxylon brasiletto and Gyroscarpus americanus, and the spatial heterogeneity of regeneration in relationship to terrain slope and crown exposure to direct sunlight were examined in the Chacocente National Wildlife Refuge, Nicaragua. Data on all individuals above 10 cm in height and below 5 cm in diameter at breast height were recorded for three consecutive years from 2001 to 2003. The density of seedlings and saplings varied significantly among species, as well as over time. The mean density of seedlings across the census year was thirty-seven, twenty and four individuals per 2 ha for G. americanus, C candidissimum and H. brasiletto, respectively. C. odorata did not regenerate at all. Similarly, the mean density of saplings in a 2-ha plot was fifty-five, twenty and two for G. americanus, C. candidissimum and H. brasiletto, respectively. The change in population density of seedlings and saplings was positive for C candidissimum, indicating continuous and advanced regeneration of this species. For G. americanus and H. brasiletto the seedling population declined while the sapling population increased. For G. americanus and C. candidissimum, seedling and sapling population densities varied with respect to the slope of the terrain and crown exposure to direct sunlight, resulting in a clumped pattern of regeneration. We concluded that natural regeneration alone may not be sufficient to maintain desired stocks of these species, and immediate restoration measures should be taken to assist the natural regeneration process.