Eucalypt growth in monoculture and silvopastoral systems with varied tree initial densities and spatial arrangements

Abstract

Brazil has large stretches of degraded land, mainly occupied by pasture. Recently, the Brazilian government created a program providing financial support to recover these lands throughout the country by establishing agroforestry systems, among others. To select the most appropriate initial spatial arrangements and tree planting density for such systems, the plant growth and leaf area index (LAI) of a Eucalyptus camaldulensis clone were evaluated in five spatial arrangements: 3.6 9 2.5 m, and 3.3 9 3.3 m (monoculture), and (2 9 2) ? 10 m, (3 9 3) ? 9 m, and 9 9 3 m (silvopastoral systems), with 1,111, 918, 833, 556 and 370 plants per hectare, respectively. The arrangement did not affect plant height growth (p [ 0.05) up to 50 months. The average diameter was affected by plant proximity in the planting line, being smaller (p \ 0.05) in the arrangements (2 9 2) ? 10 m, and 3.6 9 2.5 m, and by the number of lines in the rows, as the plants in the single line arrangement (9 9 3 m) attained the highest diameter. Individual volumes of high initial density stand were lower than in the silvopastoral systems. The arrangements (2 9 2) ? 10 m, 3.6 9 2.5 m, and 3.3 9 3.3 m did not differ (p [ 0.05) in volume per hectare, which was higher (p \ 0.05) than for the other arrangements studied. LAI decreased with age and it was higher (p \ 0.01) in the monoculture as compared to the silvopastoral systems. The silvopastoral system can be established in the (2 9 2) ? 10 m arrangement for high biomass production besides having the additional benefit of financial returns from the pasture, as compared with the monoculture. The 9 9 3 m arrangement is preferable for large diameter log production.

Estimativas da produção e propriedades da madeira de eucalipto em Sistemas Agroflorestais

“…Estudos sobre a viabilidade econômica destes Sistemas normalmente consideram apenas o crescimento das árvores e a produção volumétrica de madeira (CORDEIRO; SILVA, 2010;PAULA et al, 2013), desconsiderando suas características tecnológicas, que podem variar de acordo com o espaçamento de plantio e idade de corte das árvores. Sendo assim, estimativas da densidade básica, do teor de carbono e de energia, são importantes para uma análise mais consistente sobre a viabilidade da produção de madeira nestes Sistemas, conforme destacado por Santos et al (2012).…”

Thinning effect on plant growth of pruned eucalypt clone

“…The increase in growth resources after thinning favors the growth of the retained trees (ASSMANN, 1970). According to Paula et al (2013) there is a decrease in diameter with the increasing proximity of plants in the planting line due to greater competition between plants, even if there is a large distance between tree planting rows. Thus, an increasing effectiveness of the thinning treatments depends on its weight and on plant distribution after thinning.…”

Accumulation of carbon and age of thinning of the tree component in agroforestry systems

“…In the studies of Paula et al (2013) and Barbosa (2015) in the city of Vazante -MG, an asymptotic curve value of 109.84 m³ ha -1 was found for volume at a spacing of 9 m x 3 m (27 m² plant ) at 84 months. Apart from the clones used in each AFS, the nutritional factors and the edaphoclimatic factors of each area, it is noticed that, compared to the present study, the larger the useful area of the plant, the smaller is the asymptotic value of the curve.…”

“…In the studies conducted by Paula et al (2013) and Resende et al (2004) in forest monocultures of Eucalyptus sp. planted at denser spacing, TTA ranged from 48 to 59 months depending on the site index of the area.…”