Potential Carbon Sequestration in Rubber Tree Plantations in the Northwestern Region of the Paraná State, Brazil
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Acta Scientiarum http://www.uem.br/acta ISSN printed: 1679-9275 ISSN on-line: 1807-8621 Doi: 10.4025/actasciagron.v36i2.17404 Potential carbon sequestration in rubber tree plantations in the northwestern region of the Paraná State, Brazil Selma Regina Maggiotto1*, Dalziza de Oliveira2, Celso Jamil Marur2, Sonia Maria Soares Stivari3, Monique Leclerc4 and Claudia Wagner-Riddle5 1Universidade de Brasília, s/n, 70910-900, Brasília, Distrito Federal, Brazil. 2Instituto Agronômico do Paraná, Londrina, Paraná, Brazil. 3Departamento de Física, Universidade Estadual de Maringá, Maringá, Paraná, Brazil. 4Laboratory for Environmental Physics, University of Georgia, Athens, United States of Amerca. 5School of Environmental Sciences, University of Guelph, Guelph, Ontário, Canada. *Author for correspondence. E-mail: [email protected] ABSTRACT. Rubber tree plantations may improve the soil’s physical and chemical properties, and they may sequester atmospheric carbon in the biomass or the soil. However, the potential role of these plantations in sequestering carbon in the soil and plant biomass has not been fully evaluated. This study evaluated rubber tree plantations at Paranapoema, which is located in the northwestern region of the Paraná state of Brazil, to measure the biomass in plantations of different ages and to determine the organic carbon content and 13C in the soils. Biomass accumulation was evaluated using the destructive method in plantations of different ages. The total carbon stock in the top 60 cm of the soil was 63.4 Mg C ha-1 for the pasture adjacent to the plantations and 66.8 and 79.3 Mg C ha-1 for the 4- and 15-year-old rubber tree plantations, respectively. These values are equivalent to an annual increase in soil carbon stocks of 0.85 and 1.06 Mg ha-1, respectively, and they do not include the accumulation of carbon as tree woody biomass. The soil 13C indicated a relatively fast conversion from the previous C4-C (pasture; Brachiaria-Urochloa brizantha) to C3-C (rubber tree). The results from this study suggest that rubber tree plantations have untapped potential to sequester carbon over a relatively short time period. Keywords: rubber tree, Hevea brasiliensis, soil 13C, isotopic ratio, soil carbon stocks. Potencial de sequestro de carbono em seringais no noroeste do Paraná, Brasil RESUMO. O plantio de seringueiras é uma opção para melhorar as propriedades físicas e químicas do solo e promover o sequestro de carbono atmosférico, seja na biomassa ou no solo. Apesar das vantagens, o potencial de sequestro de carbono dos seringais no solo e na biomassa não foi ainda avaliado. Um estudo foi conduzido em seringais localizados em Paranapoema, na região noroeste do Paraná, com os objetivos de medir a biomassa em seringais de diferentes idades, e determinar o conteúdo de carbono e o 13C do solo. O acúmulo de biomassa foi avaliado pelo método destrutivo em seringais de diferentes idades. O estoque total de carbono até 60 cm do solo foi de 63,4 Mg C ha-1 na pastagem adjacente aos seringais, 66,8 e 79,3 Mg C ha-1 nos seringais de 4 e 15 anos de idade, respectivamente, equivalendo a uma taxa anual de aumento de carbono no solo de 0,85 e 1,06 Mg ha-1, sem considerar o acúmulo de carbono pela biomassa da planta. Os valores de 13C do solo indicaram uma conversão relativamente rápida do carbono proveniente de plantas C4 (pastagem, Brachiaria-Urochloa brizantha) para carbono de plantas C3 (seringal). Os resultados deste estudo indicam o grande potencial de seringais em sequestrar carbono em um período relativamente curto. Palavras-chave: seringueira, Hevea brasiliensis, 13C do solo, razão isotópica, estoque de carbono no solo. Introduction monoculture or combined with other crops in agroforestry systems, may also sequester carbon from The state of Paraná, is the southernmost state in the atmosphere (DEY, 2005; YANG et al., 2005; GUO Brazil where the climatic characteristics are adequate to et al., 2006). support the growth of rubber tree plantations Plant biomass estimates in rubber tree plantations (CAMARGO et al., 2003). By the year 2000, more of different ages and grown in potentially dissimilar than 1000 ha of rubber trees were established and conditions in southern Brazil (CUNHA et al., 2000; productive in Paraná (PEREIRA et al., 2000). The COTTA et al., 2006; WAUTERS et al., 2008) and Asia establishment of rubber tree plantations has been (DEY, 2005; YANG et al., 2005) have revealed a large proposed as an option to improve physical and range of carbon accumulation rates, from 1.4 to 6.7 Mg chemical soil properties by protecting the soil from C ha-1 yr-1. However, fewer studies have investigated erosion and recycling nutrients through leaf litterfall changes in the soil carbon accumulation rates beneath (PEREIRA et al., 2000). These plantations, as a rubber tree plantations. For example, when compared Acta Scientiarum. Agronomy Maringá, v. 36, n. 2, p. 239-245, Apr.-June, 2014 240 Maggiotto et al. to adjacent agricultural areas, an accumulation rate of At the time of sampling, the trees were 4, 6 and 15 0.72 Mg C ha-1 yr-1 was reported to a depth of 1 m in years old. Only the oldest stand was being tapped. China (YANG et al., 2005). Carbon isotopic ratio measurements have been Rubber tree biomass sampling and analysis used to gain information regarding changes in soil The quantification of the above- and belowground carbon associated with land use. Because the tree biomass values was completed in February 2003 photosynthetic process discriminates against 13C for each of the three plantations. The diameter at the differently in C3 and C4 plants (FRY, 2006), the 13C breast height (dbh) of 80 trees was measured in each of the soil organic matter can be used to reflect the stand. Four trees in each area, which were long-term source of plant material, and this measure representative of the stand’s mean dbh (8.3, 12.5, and can be used to quantify carbon addition to the soil from 21.9 cm for the 4-, 6- and 15-year-old trees, the vegetation. respectively) were selected for destructive sampling. The present study addresses the question of how After felling each tree, the aboveground biomass was much carbon can be sequestered by a rubber tree separated into leaves, large branches (> 4 cm plantation by performing the following two analyses: diameter), small branches (< 4 cm diameter), dry biomass measurements in rubber tree stands of branches, and tree trunks. The belowground biomass different ages in adjacent areas to estimate the biomass was measured by excavating areas of 1, 4 and 6.25 m2 accumulation rate and soil carbon and isotopic carbon around each tree stump for the 4-, 6- and 15-year-old determination in soils to study the carbon storage trees, respectively, to a depth of 1 m. The roots were change that is associated with the conversion from a separated from the loosened soil by hand picking and pasture to a rubber tree plantation. sieving. The taproot was removed from the soil using a tractor equipped with a front-end loader. The Material and methods belowground biomass was separated into the root Study Site stump, primary roots, lateral roots and loose roots. The fresh weight of each component of the The study site is located at Fazenda Guanabara in above- and belowground tree biomass was Paranapoema (22º43’S, 57º07’W) in the northwestern determined in the field. For the tree trunk and large region of the Paraná state of Brazil. The location is 400 branches, sub-samples were taken from the lower, m above sea level, and the climate is classified as humid mid and upper one-third regions. Sub-samples (500 subtropical (Cfa according to the Köppen classification, g fresh weight) of each component were taken and LUTGENS; TARBUCK, 2004); the average annual used for further laboratory analyses. The plant temperature is 22ºC, and the total annual precipitation samples were dried at 60ºC until they reached a is 1500 mm. The soil at this site was classified as Oxisol constant weight, and the fresh biomass water according to the United States Department of content was determined. The plant material was Agriculture (USDA) Soil Taxonomy (Latossolo ground in a Wiley Mill (passed through a 1 mm Vermelho in the Brazilian Soil Classification System). screen). The total carbon content was determined The soil has a loamy sand texture (85% sand, 1% silt using the Walkley-Black method. The samples of and 14% clay) and a pH (CaCl2) of 4.0 at a 0-20 cm the plant components were also analyzed using the depth. dry combustion method to calibrate the wet Historically, this area was occupied by a seasonal digestion method. The 13C of the plant samples semideciduous forest and contained a large diversity of was determined using a Tracemass Isotope Ratio species, which were predominantly classified in the Mass Spectrometer (Europa Scientific, Crewe, UK) Caesalpiniaceae, Euphorbiaceae, Myrtaceae and at the Isotope Analytical Laboratory, University of Fabaceae families (SOUZA; BATISTA, 2004). In Saskatchewan, Saskatoon, Canada. In the results 1950, the forest was cleared and planted with coffee section, the means of four samples and the standard (Coffea arabica). In July 1975, when a severe frost killed errors are presented. all of the coffee plants, the area was planted with pasture grass (Brachiaria-Urochloa brizantha) to support Soil sampling and soil carbon determination extensive cattle grazing. In 1988, 1997 and 1999, nearby Soil samples for organic carbon determination areas within the pasture were planted with rubber trees were taken in April 2003 from the 4- and 15-year- (Hevea brasiliensis) in plots that ranged in size from 125 old plantations; they were taken in the area at two to 250 ha.