Individual study: The potential of 20 native tree species for soil rehabilitation in Atlantic Forest, Pau Brasil Ecological Station, Bahia, Brazil
Montagnini F. Fanzeres A. & Da Vinha S.G. (1995) The potentials of 20 indigenous tree species for soil rehabilitation in the Atlantic Forest region of Bahia, Brazil. Journal of Applied Ecology, 4841-856
By the beginning of the 1990s the Atlantic forests of the east coast of Brazil had been reduced to 12 % of that four centuries earlier. The goal of this study was to identify indigenous tree species with a positive influence on soil fertility in order to design mixed-tree and tree/crop systems for the Atlantic forest region of Bahia, eastern Brazil.
Study site: The study focused on native tree species growing in an arboretum at Pau Brasil Ecological Station (1,145 ha), Bahia, Brazil. Although the small size of the areas sampled and the lack of adequate replication limits the interpretation of the results, the pure tree stands offered a unique opportunity to evaluate nutrient cycling characteristics of several tree species which could be useful for future utilization in land rehabilitation schemes.
Tree species: Twenty native tree species chosen for good growth and economic potential, and as all were found in the natural forest reserve at the Station. All the trees were in pure stands of 36 individuals spaced at 2 x 2 m on the same soils and were 14-15 years old (planted 1974-75). For comparison, soils were sampled from 25-year-old secondary forest, primary forest and a mixed species plantation all at the Station.
Soil analysis: Soils for chemical analysis and bulk density were sampled under a 25-year-old secondary forest, a mixed-species plantation, the native forest and under the 20 species in question. Forest-floor litter and live leaf samples were analysed for N, P, K, Ca, Mg and Al.
Soil fertility was higher in secondary than in primary forest. The mixed plantation had similar soil pH, C, N and Mg, slightly higher P, and lower K and Ca than the primary forest. Litter accumulation on the floor was larger in secondary than in primary forest. Litter nutrients were also higher in secondary than in primary forest.
Positive effects on soils were noted under 15 of the 20 species studied including Inga affinis, Parapiptadenia pterosperma (leguminous N-fixing species); Arapatiella psilophylla, Caesalpinia echinata (leguminous, non-N-fixers); and Eschweilera ovata, Lecythis pisonis and Licania hypoleuca (other families).
Of the 20 species in the arboretum, the highest dry weights of forest-floor litter were under A.psilophylla, Bombax macrophyllum, Inga affinis, Licania hypoleuca and Pithecellobium pedicellare. A positive effect on soils were found under all of these species, P.pedicellare having the least influence. This suggests that forest-floor nutrients were incorporated in the soil via decomposition under these species.
Conclusions: Species that contribute to increased C and N (e.g. C.echinata, I.affinis, P.pterosperma and Plathymenia foliolosa) could be combined with those that increase soil pH, basic cations or both (e.g. Copaifera luscens, Eschweilera ovata, Lecythis pisonis and L.hypoleuca). Inclusion of A.psilophylla, B.macrophyllum, Buchenavia grandis, C.echinata, Cassia spp., Hymenaea aurea and I. affinis could contribute to increased extractable P levels in surface soils.
In addition to their potential effects on soil fertility, species selection for planting will necessarily be guided by seed and seedling availability, as well as by growers’ preferences and economic aspects, including establishment costs and market potential.
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