Abstract
Hybrid eucalypt clones are grown for fiber production worldwide and to provide an ecosystem service that can store atmospheric carbon at a very fast rate. This study assessed the carbon stocks in the soil and various tree fractions in a 10-year-old plantation of Eucalyptus urophylla S.T. Blake × Eucalyptus globulus Labill. in Southern Brazil. Four experimental plots were established, and an inventory of Eucalyptus trees was conducted by considering five diametric classes. Three trees in each diametric class were harvested for biomass and carbon quantification. The understory biomass of native trees was quantified in five subplots and the litter was quantified in 16 subplots. Organic C was quantified in the soil (SOC) and roots (diameter ≤ 0.5 cm) to a depth of 100 cm. The C concentration in the different biomass fractions of the eucalyptus trees were 55.7% (±0.6), 50.4% (±0.4), 49.5% (±0.6) and 45.4 % (±0.9) for leaves, branches, wood and bark, respectively. The C concentrations in the understory fractions were 51.4% (±1.0) for the canopy and 50.0% (±0.9) for the stem. The carbon concentration in the fine root biomass was 45.7% (±1.4). Soil C concentrations were 1.23% (±0.32), 0.97% (±0.10), 0.45% (±0.14), and 0.24% (±0.10) for depths of 0–25, 25–50, 50–75, and 75–100 cm. C was allocated in: (a) the trees (aboveground fraction = 118.45 Mg ha−1 and belowground fraction = 30.06 Mg ha−1), (b) the understory = 1.44 Mg ha−1, (c) the litter = 8.34 Mg ha−1, and (d) the soil (without roots) = 99.7 Mg ha−1. The share of total C stock (a + b + c + d = 258.0 Mg ha−1) was similar in the aboveground (49.7%) and belowground (50.3%) fractions, thus indicating a very high rate of C sequestration in the biomass. Eucalyptus plantations in Brazil are fast growing (for this study = 36.7 m³ ha−1 year−1) and contribute to intense carbon sequestration in above and belowground biomass (14.8 Mg ha−1 year−1).
Highlights
Demand for wood products has grown strongly in recent years, thereby increasing interest in the use of land for fast-growing tree plantations
In Brazil, the total area covered by forest plantations in 2017 was about 9.8 M ha [1], yielding 91% of the wood destined for industrial purposes [2]
To calculate the total carbon accumulated in the litter layer, we considered that the carbon content represented 50% of the dry matter
Summary
Demand for wood products has grown strongly in recent years, thereby increasing interest in the use of land for fast-growing tree plantations. In Brazil, the total area covered by forest plantations in 2017 was about 9.8 M ha [1], yielding 91% of the wood destined for industrial purposes [2]. Eucalyptus was first introduced to Brazil more than 150 years ago. Plantations of the species cover an area of. 7.4 M ha and represent 75.2% of all forest plantations in the country [1] and yield on average 39 m3 ha−1 year−1 [2]. Eucalyptus has been planted extensively in Brazil in the past 10 years, with an increase of about 70% in plantations of the species in the period. The main products are pulp, paper, wood panels, laminate flooring, plywood panels, furniture, other solid wood products, and charcoal and biomass for energy purposes [2]
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