Assessment of nutrient returns in a tropical dry forest after clear-cut without burning

• Published in: Nutrient cycling in agroecosystems Vol. 100; no. 3; pp. 333 - 343
• Main Authors: Amorim, L. B, Salcedo, I. H, Pareyn, F. G. C, Alvarez, I. .A
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer-Verlag 01.12.2014; Springer Netherlands; Springer; Springer Nature B.V
• Subjects: aboveground biomass; Agricultural management; Agriculture; Agronomy. Soil science and plant productions; Animal and plant ecology; Animal, plant and microbial ecology; Biodegradation; Biological and medical sciences; Biomedical and Life Sciences; branches; Bromeliaceae; Burning; Burning rate; Clearcutting; Debris; Decomposition; Deforestation; Detritus; Dry forests; Dry matter; Environmental degradation; Forest floor; forest litter; Forestry; Forests; fuelwood; Fundamental and applied biological sciences. Psychology; General agroecology; General agroecology. Agricultural and farming systems. Agricultural development. Rural area planning. Landscaping; General agronomy. Plant production; Generalities. Agricultural and farming systems. Agricultural development; Leaves; Life Sciences; Litter; Livestock; Nutrient loss; Nutrients; Original Article; Rainforests; Rainy season; slash; Soil degradation; Soil layers; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Synecology; Timber; Tropical forests; wet season; Wood; South America; Brazil; America; Debris decomposition; Nutrient cycling; Litter decomposition; Caatinga; Translocation; Xerophyte; Litter; Tropical zone; Decomposition; Tropical forest; Biogeochemical cycle; Inorganic element; Agroecosystem; Burning; Soils; Clearcutting; Nutrient; Debris; Shrubbery
• ISSN: 1385-1314; 1573-0867
• DOI: 10.1007/s10705-014-9646-5

Tropical dry forests (TDFs) are being deforested at unprecedented rates. The slash/burn/agriculture/fallow-extensive livestock sequence causes significant nutrient losses and soil degradation. Our aim is to assess nutrient inputs and outputs in a TDF area under an alternative management system, for exclusive wood production. The study involved clear-cutting a preserved caatinga TDF site without burning, quantifying nutrients exported in firewood/timber and nutrients returned to the soil from the litter layer plus the slash debris, left to decompose unburned on the soil surface. Before clear-cut, the litter layer on the forest floor contained 6.1 t ha of dry matter (DM). After clear-cut, the aboveground biomass was 61.9 t DM ha⁻¹(consisting of 21.5 t DM ha⁻¹of commercial wood and 40.4 t DM ha⁻¹of clear-cut debris that did not include the underlying litter layer). The litter layer was composed of fine and coarse litter, with turnovers of 0.86 and 0.31 year⁻¹, respectively, separately measured in uncut control plots during two rainy seasons (Dec-2007/June-2008 and Dec-2008/June-2009). In a single season, its decomposition returned to the soil 48.4, 1.16 and 12.3 kg ha⁻¹of N, P and K. The clear-cut debris was mainly composed of branches, 33.4 t ha⁻¹, bromeliads, 5.63 t ha⁻¹and green leaves, 1.32 t ha⁻¹. In-situ decomposition rates for branches and bromeliads were 0.24 and 1.47 year⁻¹, respectively. After two rainy seasons the clear-cut debris released 206, 6.5 and 106 kg ha⁻¹of N, P and K respectively. This input plus that of the underlying litter layer exceeded exports in the commercial wood, and replenished a soil nutrient stock (0–30 cm) of approximately the same magnitude.