Decomposition rates of forest residues and soil fertility after clear‐cutting of Eucalyptus grandis stands in response to site management and fertilizer application

Abstract

Forest residues (i.e. harvest residues and litter) are important nutrient sources for trees because soils of poor fertility are used for eucalypt plantations in Brazil. Understanding the dynamics of decomposition for these residues and their effects on soil fertility are relevant for the management of forest plantations. The objectives with this study were to assess the effects of forest residue management and fertilizer, both applied in the establishment of a Eucalyptus grandis Hill ex Maiden stand, on the decomposition rate (k), nutrient release and soil fertility after harvest of this stand. The treatments were applied to a plantation (R1). After 8 yr, R1 was clear‐cut and all of the treatments were reapplied to a new planting (R2). At the end of R1 (age of 8 yr), there was a reduction of 10% in the wood volume in the treatment with the forest residues removed and 36% reduction with no fertilizer application. At the end of 1 yr for plantation R2, these reductions were 30 and 57%, respectively. Residue decomposition under R2 was assessed by a new approach that involved collecting samples directly on the site without using litter bags. The k of forest residues was 3.6 for leaves, 1.2 for bark and 0.8 for branches. The application of small rates of N and P fertilizer did not influence the k of forest residues. In the first 300 days after clear‐cutting, approximately 50% of N, P, Ca, Mg and S and 80% of K in the forest residues were released. Even so, this did not result in significant changes in soil fertility levels. Only small reductions in soil N and P contents over time and changes in topsoil pH resulted from forest residue removal.

Contribution of Harvest Residues to Nutrient Cycling in a Tropical Acacia mangium Willd. Plantation

“…The patterns of mass loss during decomposition varied among components, with leaves decaying the fastest, consistent with previous reports for hardwood plantation species [16,17,20,41,50]. Among nutrients in decomposing material, the concentration of N is the most important factor determining the rate of decomposition in a given environment [29,30].…”

“…While burning can initially improve soil fertility, it can also lead to large losses of N via volatilisation [10][11][12][13], and P, Ca, and K through leaching, as well as water and wind erosion [13][14][15]. Retention of harvest residues, especially bark, acts to conserve nutrients and leads to their controlled release in a way that minimizes losses from leaching and potentially supplies the amount of nutrients required for stand development in the next rotation [16][17][18][19][20]. Hence, understanding decomposition rates and nutrient release from harvest residues, including bark, is important for informing residue and nutrient management over successive rotations.…”

Effect of Timber Harvest Intensities and Fertilizer Application on Stocks of Soil C, N, P, and S

“…The use of harvest residues as soil coverage can protect the soil against erosion, improve or maintain the SOC, and improve both the quantity and availability of nutrients stored in the soil [5,11,15].…”

“…While most temperate ecosystems-which are usually N limited-may store added mineral N for long periods, a P limited tropical forest can rapidly loose substantial amounts of mineral N (NO 3 − and NH 4 + ) following N fertilization [8]. The nutrient limitations of tropical soils not only decrease plant productivity but also impact decomposition rates and immobilization processes and therefore the soil's capacity to store and cycle C and N [9][10][11].…”

Dinâmica de incremento da área seccional do tronco e do dossel de povoamentos clonais de eucalipto em função de variáveis edafoclimáticas e nutricionais

“…Em plantações clonais de Eucalyptus, a demanda nutricional por N, P, K, Ca e Mg é elevada, tornando a fertilização mineral e demais práticas conservacionistas, como o cultivo mínimo do solo, essenciais Rocha et al, 2016). Embora respostas sejam mais recorrentes para P e K nos trópicos e subtrópicos (Laclau et al, 2010;Gonçalves et al, 2011), aplica-se doses de N, Ca e Mg, como fertilização de reposição (Pulito et al, 2015;Melo et al, 2016).…”