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Albuquerque E.R.G.M.,Federal Rural University of Pernambuco | Sampaio E.V.S.B.,Federal University of Pernambuco | Pareyn F.G.C.,Associacao Plantas do Nordeste APNE | Araujo E.L.,Federal Rural University of Pernambuco
Journal of Arid Environments | Year: 2015

Aboveground and root biomass and the root:shoot ratio were determined in six areas of caatinga. The aboveground biomass was estimated using allometric equation. The root biomass was collected from 0.5×0.5m2 trenches, opened under stem bases and in areas away from the stem bases, separated in 20cm deep layers down to 1m. Roots were separated into five diameter classes: < 2mm; 2.1-5mm; 5.1mm-10mm; 10.1-20.0mm; and >20.1mm. The total aboveground biomass was 46.5Mgha-1. The root biomass in trenches under the stem base was ten times higher than in the other trenches but the area of the stem bases was 11 times smaller, so root biomass under the bases was 41% of the total root biomass (10.6 and 25.6Mgha-1, respectively). The root:shoot ratio was 0.56. The highest proportion of roots was in the upper soil layer and under the stem base and most of them were coarse roots (>20.1mm). It is essential to consider the root biomass below the stem base to obtain a proper estimation of the root biomass. © 2015 Elsevier Ltd.

Sampaio E.,Federal University of Pernambuco | Gasson P.,Royal Botanic Gardens | Baracat A.,Royal Botanic Gardens | Cutler D.,Royal Botanic Gardens | And 2 more authors.
Forest Ecology and Management | Year: 2010

Allometric equations have been developed for various different vegetation types but have rarely been validated in the field and never for dry tropical forest such as caatinga. In three areas of semi-arid Brazil, with regenerating caatinga vegetation, we measured and weighed twelve hundred individuals of four tree species and used the data to validate equations previously determined in mature caatinga. They and several other equations developed for tropical vegetations overestimate the biomass (B) of trees from the regeneration areas by more than 20%, possibly because these trees have reduced crowns, with lower branch masses. We then determined new allometric equations for them, validating equations for one site against data of the others and pooling the data if they were cross-validated. The best equations were power ones, based on diameter at breast height (D), with little improvement by including height, crown area and/or wood density (Caesalpinia pyramidalis, B = 0.3129D1.8838; Croton sonderianus, B = 0.4171D1.5601; Mimosa ophthalmocentra, B = 0.4369D1.8493; and Mimosa tenuiflora, B = 0.3344D1.9648 and 0.4138D1.7718). © 2010 Elsevier B.V. All rights reserved.

Amorim L.B.,Instituto Nacional do Semiarido INSA | Amorim L.B.,National Institute of Semiarid INSA | Salcedo I.H.,Instituto Nacional do Semiarido INSA | Pareyn F.G.C.,Associacao Plantas do Nordeste APNE | Alvarez I.A.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuária
Nutrient Cycling in Agroecosystems | Year: 2014

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−1 of commercial wood and 40.4 t DM ha−1 of 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−1 of N, P and K. The clear-cut debris was mainly composed of branches, 33.4 t ha−1, bromeliads, 5.63 t ha−1 and 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−1 of 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. © 2014, Springer Science+Business Media Dordrecht.

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