| 1. |
|
|
| 2. |
- Tigabu, Mulualem, et al.
(författare)
-
Germination requirements and seedling establishment of four dry forest species from Nicaragua
- 2011
-
Ingår i: Tropical Ecology -Allahabad-. - 0564-3295. ; 52, s. 1-11
-
Tidskriftsartikel (refereegranskat)abstract
- We examined the optimal temperature and light requirements for seed germination of Bombacopsis quinata, Cordia alliodora, Lysiloma divaricatum and Tabebuia rosea and establishment of B. quinata, C. alliodora and T. rosea seedlings planted under different light conditions. Seeds of L. divaricatum germinated rapidly and to a large extent at all constant temperature regimes (15-35 degrees C) both in light and darkness. Exposure of seeds to alternating temperatures of 20/15 degrees C resulted in 58 % germination in darkness and 62 % in light. C. alliodora and T. rosea seeds germinated equally well at constant temperature regimes ranging from 20 degrees C to 35 degrees C in light and darkness. Exposure to alternating temperatures (20/15 degrees C) resulted in higher germination for seeds of C. alliodora in dark than in light, while it inhibited the germination of T. rosea seeds. Seeds of B. quinata incubated at 20 degrees C and 25 degrees C in light and 20 degrees C in darkness exhibited the highest germination while exposure to alternating temperatures completely arrested germination in this species. Survival of C. alliodora seedlings was higher on open and partially-open sites than on-the site under closed canopy. B. quinata had the lowest survival while T. rosea had the highest on the open site. The findings are discussed in relation to the restoration of abandoned sites. We concluded that while C. alliodora and T. rosea could potentially serve as framework species for the restoration of degraded and/or abandoned sites, B. quinata does not meet the requirements of a framework species for restoring degraded sites in drier regions.
|
|
| 3. |
|
|
| 4. |
- Tigabu, Mulualem, et al.
(författare)
-
Soil Seed Banks and Regeneration of Neotropical Dry Deciduous and Gallery Forests in Nicaragua
- 2009
-
Ingår i: Bois Et Forets Des Tropiques. - 0006-579X. ; 299, s. 49-62
-
Tidskriftsartikel (refereegranskat)abstract
- Today, the depletion of tropical dry forests and the need for their restoration are well recognized. In restoring degraded forests, the first step is to quantify the actual and potential levels of natural regeneration, examining the role of soil seed banks as propagule donors. In this study, we assessed the composition, density and spatial distribution of the soil seed bank and seedling populations in dry deciduous and gallery forests of the Chacocente Wildlife Refuge in Nicaragua. A total of 17 species were found in the soil seed bank of the deciduous forest, with a viable seed density of 466 seeds/m(2). In the gallery forest, a total of 24 species were found in the soil seed bank with a viable seed density of 1257 seeds/m(2). The spatial analysis of the soil seed bank revealed clumped and uniform distributions in both forests, depending on the species. The total seedling density in the deciduous and gallery forests was 62 50 and 6600 individuals/ha, respectively. The spatial distribution of seedling populations varied from clumped to uniform depending on the species. The similarity between the soil seed bank, seedling layer and above-ground vegetation was low in both forest sites. It may be concluded that the number of seed bank species and the quantity of soil-stored seeds are relatively low. Regeneration was abundant in some species, but poor in many others. The natural regeneration process should therefore be assisted through direct seeding, planting seedlings and manipulation of the site to improve environmental conditions for seedling establishment and growth.
|
|
| 5. |
|
|
| 6. |
- González-Rivas, Benigno, et al.
(författare)
-
Regeneration of dry forest species Population dynamics and spatial distribution of seedlings and saplings of four dry forest species in Nicaragua
- 2009
-
Ingår i: Bois Et Forets Des Tropiques. - 0006-579X. ; 63, s. 21-31
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
