Evaluation of the throughfall and stemflow nutrient contents in mixed and pure plantations of Acacia mangium, Pseudosamenea guachapele and Eucalyptus grandis

Abstract

The interception of the rainfall by the forest canopy has great relevance to the nutrient geochemistry cycle in low fertility tropical soils under native or cultivated forests. However, little is known about the modification of the rainfall water quality and hydrological balance after interception by the canopies of eucalyptus under pure and mixed plantations with leguminous species, in Brazil. Samples of rainfall (RF), throughfall (TF) and stemflow (SF) were collected and analyzed in pure plantations of mangium (nitrogen fixing tree -NFT), guachapele (NFT) and eucalyptus (non-nitrogen fixing tree -NNFT) and in a mixed stand of guachapele and eucalyptus in Seropédica, State of Rio de Janeiro, Brazil. Nine stemflow collectors (in selected trees) and nine pluviometers were randomly disposed under each stand and three pluviometers were used to measure the incident rainfall during 5.5 months. Mangium conveyed 33.4% of the total rainfall for its stem. An estimative based on corrections for the average annual precipitation (1213 mm) indicated that the rainfall's contribution to the nutrient input (kg ha-1) was about 8.42; 0.95; 19.04; 6.74; 4.72 and 8.71 kg ha-1 of N-NH4+, P, K+, Ca+2, Mg+2 and Na+, respectively. Throughfall provided the largest contributions compared to the stemflow nutrient input. The largest inputs of N-NH4+ (15.03 kg ha-1) and K+ (179.43 kg ha-1) were observed under the guachapele crown. Large amounts of Na+ denote a high influence of the sea. Mangium was the most adapted species to water competitiveness. Comparatively to pure stand of eucalyptus, the mixed plantation intensifies the N, Ca and Mg leaching by the canopy, while the inputs of K and P were lower under these plantations.

Nutrient Input via Incident Rainfall in a Eucalyptus dunnii Stand in the Pampa biome

“…This pattern was verified in Eucalyptus dunnii (Corrêa, 2011), Eucalyptus grandis (Balieiro et al, 2007;Laclau et al, 2010), Eucalyptus sp. (Laclau et al, 2003), Eucalyptus urophylla × Eucalyptus grandis (Laclau et al, 2010), and Eucalyptus globulus (Ashagrie & Zech, 2010).…”

Quantificação de nutrientes na precipitação em um plantio de Eucalyptus urophylla x Eucalyptus globulus subsp. maidenii, Eldorado do Sul, RS

“…A correlação negativa entre os parâmetros pode estar relacionada com o efeito de diluição dos íons em função dos volumes precipitados (LACLAU et al, 2003;CALIL, 2008), conforme já abordado anteriormente. Ao contrário do que alguns trabalhos da literatura evidenciaram (ZHANG et al, 2006;BALIEIRO et al, 2007), não ocorreu correlação positiva entre os teores de potássio e a PI (Tabela 3), talvez pelo efeito de diluição do íon nas amostras ao invés do processo de lixiviação em função da chuva. Scheer (2009) ).…”

Plantio misto Eucalyptus spp. com leguminosas arbóreas fixadoras de nitrogênio

“…Forrester et al (2007) observaram, aos dez anos de idade do povoamento em espaçamento de 3,3 m × 3,0 m, uma taxa média de fixação de nitrogênio atmosférico de 38 e 86 kg ha -1 ano -1 , para a A. mearnsii em plantio misto (50E:50A) e em monocultivo, respectivamente. Outro fator importante na disponibilidade de nitrogênio no sistema é a sua entrada pela água da chuva que, segundo Balieiro et al (2007), é intensificada pela espécie leguminosa, podendo chegar a 12,89 kg ha -1 ano -1 (NH 4 ) em consórcios de E. grandis e Pseudosamenea guachapele em espaçamento de 3,0 m × 1,0 m.…”