Factors Limiting the Survival of Native Tree Seedlings Used in Conservation Efforts at the Edges of Forest Fragments in Upland Madagascar

Abstract

We tested four reforestation techniques in tropical forest fragments that were damaged by fire in upland Madagascar. We conducted a full-factorial experiment on the survival of transplanted seedlings of five native tree species in grassland plots adjacent to the forest fragments in the Ambohitantely Forest Reserve. The species studied were Dodonaea madagascariensis, Filicium decipiens, Olea lancea, Podocarpus madagascariensis, and Rhus taratana. A total of 480 seedlings were planted; 207 survived the 15 months of the experiment. The factors examined were distance of the reforestation plots from the forest, mixing of forest soil into the plots, application of chemical fertilizers, experimental shading of plots, and the cover of naturally establishing shrubs. Both increasing the distance of plots from the forest edge and adding chemical fertilizers significantly reduced the survival of all seedlings. The surprising negative effects of fertilization may be partly due to increased competition from naturally establishing shrubs that are adapted to exploit high nitrogen levels. Mixing soil from the forest areas into the plots did not change seedling survival. Shading reduced the survival of D. madagascariensis seedlings and did not increase the survival of any species. These findings suggest that the success of reforestation projects can be increased by planting seedlings close to the existing forest fragments. Reforestation of similar tropical forests is likely to be more successful if efforts are focused on expanding the size of existing fragments of tropical forest, rather than on establishing new fragments in grassland openings.

Germination and initial growth of tree seedlings on deforested and natural forest soil at Dulhazara, Bangladesh

“…Instead of favorable condition for seed germination in deforested land at Dulhazara, germination rate of the studied species were quite low when compared to findings from Pareliussen et al (2006) and Anderson (1866), because of excessive biotic interference i.e. wildlife (deer, sambur, wild boar among others in forest soil seedbeds and domestic animals (cows, dogs, goats, etc.)…”

Survival and growth of seedlings of 19 native tree and shrub species planted in degraded forest as part of a forest restoration project in Madagascar’s highlands

“…The lower survival rate reported in this experiment compared to the current study may be due to its longer experimental period (15 months compared to ten months) and differences in experimental conditions. With respect to the latter, it is notable that Pareliussen et al (2006) planted their seedlings in grassland whereas in the current study seedlings were planted within wooded grassland at the edge of the former forest where the environment might be expected to be closer to that within the forest. Pareliussen et al (2006) found best survival close to the forest compared to relatively far from the forest.…”

“…Pareliussen et al (2006) studied the survival and growth rates of seedlings of five native tree and shrub species planted in grassland at various distances from forest within the RS Ambohitantely. Fifteen months after planting, survival of these species ranged from 40 % to 51 %.…”

“…The highest average monthly temperature (23.7 °C) occurs in November, and the lowest (13.5 °C) in August. Fogs are particularly frequent in the dry and cool season (Ratsirarson and Goodman 2000, Pareliussen et al 2006). The soil at Ankafobe Forest is an acid red laterite with high clay content (Ratsirarson and Goodman 2000).…”

“…Ambalabe, Analalava, Mahabo, Sahamalaza, Tampina and Tampolo, (Sustainable Agriculture and Natural Resource Management Collaborative Research Support Program 2005, Birkinshaw et al 2009) include more modest restoration or at least reforestation using native species activities around their fringes. The production and plantation of the young plants used by these projects requires significant investment yet there is little exchange of knowledge among the diverse practitioners in different parts of the country that could help improve methodologies employed and their resultant impact (but see Holloway (2000) and Pareliussen et al (2006)). …”