Abstract:We investigated annual litterfall and leaf decomposition rate in a cerrado site. We collected woody plant litter monthly from April 2001 to March 2002 and from July 2003 to June 2004. We placed systematically 13 litter traps (0.5 x 0.5 m) in a line, 10 m one from the other. We sorted litter into 'leaves', 'stems', 'reproductive structures', and 'miscellanea' fractions, oven-dried them at 80 °C until constant mass and weighed the dry material. To assess leaf decomposition rate, we packed leaves recently shed by… Show more
“…Although the mean annual litter production in ) was more than double that observed for the HSAs and TIAs, it was much lower than the 861 gm −2 and 801 g.m −2 , respectively, estimated for primary and secondary tropical forests in South America (Chave et al 2010). It was also lower than the 568 gm −2 and 509 gm −2 reported by Terror et al (2011) and Werneck et al (2001), respectively, for other semideciduous forests in the Ouro Preto region, as well as the 560 gm −2 and 565 gm −2 reported by Valenti et al (2008) and Cianciaruso et al (2006), respectively, for the cerradão (woodland savanna), although it was comparable to the 470 gm −2 and 433 gm −2 reported by Chave et al (2010) and Röderstein et al (2005), respectively, for upland forest formations on cambisols.…”
Section: Discussioncontrasting
confidence: 52%
“…We showed that the miscellaneous fraction of litter production was correlated with rainfall in all habitats (R 2 >0.42) and that the peaks in that fraction occurred mainly at the beginning of the rainy season (in October, November and December). After the leaf fraction, fragments of branches and trunks are the largest contributor to total litterfall in an ecosystem (Martins & Rodrigues 1999, Dent et al 2006Cianciaruso et al 2006, Köhler et al 2008, Valenti et al 2008. During the dry season, twigs and branches can show xylem cavitation, which results in death from embolism (Tyree & Sperry 1989).…”
Ecosystems on cangas (duricrust) present considerable heterogeneity of habitats due to microtopographic variations, soil accumulation and a variety of plant functional groups. Therefore, spatial and temporal ecosystem processes such as litterfall are to be expected to be large, and the absence of a level of productivity represents all the facets of iron--rich landscapes. We investigated litterfall in a iron-rich rock complex in the Iron Quadrangle of Brazil, with habitats formed on different evolutionary stages of the soil, resulting in a gradient of biomass, canopy cover and community structure. The measurements were made in open field areas, dominated by herb-shrub vegetation and interspersed with islands of dense vegetation in which there were individual trees, as well as in areas of semideciduous forest. The litterfall, especially that of leaf litter, followed the gradient of woody cover and was approximately two times greater in the forest formation. However, the spatial and temporal variations in deposition were greatest in the herb-shrub areas and least in the semideciduous forest area, intermediate values being obtained for the tree island areas. The peaks in litterfall also varied among habitats, occurring in some periods of the rainy season and during the transition from rainy to dry in the herb-shrub and tree island areas, whereas they occurred at the end of the dry season in the semideciduous forest area. The results show significant differences in the patterns of litterfall among different physiognomies within the same iron-rich rock complex, indicating the need for expanded studies, focusing on the flow of matter and energy in such environments.
“…Although the mean annual litter production in ) was more than double that observed for the HSAs and TIAs, it was much lower than the 861 gm −2 and 801 g.m −2 , respectively, estimated for primary and secondary tropical forests in South America (Chave et al 2010). It was also lower than the 568 gm −2 and 509 gm −2 reported by Terror et al (2011) and Werneck et al (2001), respectively, for other semideciduous forests in the Ouro Preto region, as well as the 560 gm −2 and 565 gm −2 reported by Valenti et al (2008) and Cianciaruso et al (2006), respectively, for the cerradão (woodland savanna), although it was comparable to the 470 gm −2 and 433 gm −2 reported by Chave et al (2010) and Röderstein et al (2005), respectively, for upland forest formations on cambisols.…”
Section: Discussioncontrasting
confidence: 52%
“…We showed that the miscellaneous fraction of litter production was correlated with rainfall in all habitats (R 2 >0.42) and that the peaks in that fraction occurred mainly at the beginning of the rainy season (in October, November and December). After the leaf fraction, fragments of branches and trunks are the largest contributor to total litterfall in an ecosystem (Martins & Rodrigues 1999, Dent et al 2006Cianciaruso et al 2006, Köhler et al 2008, Valenti et al 2008. During the dry season, twigs and branches can show xylem cavitation, which results in death from embolism (Tyree & Sperry 1989).…”
Ecosystems on cangas (duricrust) present considerable heterogeneity of habitats due to microtopographic variations, soil accumulation and a variety of plant functional groups. Therefore, spatial and temporal ecosystem processes such as litterfall are to be expected to be large, and the absence of a level of productivity represents all the facets of iron--rich landscapes. We investigated litterfall in a iron-rich rock complex in the Iron Quadrangle of Brazil, with habitats formed on different evolutionary stages of the soil, resulting in a gradient of biomass, canopy cover and community structure. The measurements were made in open field areas, dominated by herb-shrub vegetation and interspersed with islands of dense vegetation in which there were individual trees, as well as in areas of semideciduous forest. The litterfall, especially that of leaf litter, followed the gradient of woody cover and was approximately two times greater in the forest formation. However, the spatial and temporal variations in deposition were greatest in the herb-shrub areas and least in the semideciduous forest area, intermediate values being obtained for the tree island areas. The peaks in litterfall also varied among habitats, occurring in some periods of the rainy season and during the transition from rainy to dry in the herb-shrub and tree island areas, whereas they occurred at the end of the dry season in the semideciduous forest area. The results show significant differences in the patterns of litterfall among different physiognomies within the same iron-rich rock complex, indicating the need for expanded studies, focusing on the flow of matter and energy in such environments.
“…According to Delitti (1995), litterfall productions will have distinct relationships with rainfall patterns depending on the ecosystems in question. In Atlantic Forest and restinga (coastal, sandy soil vegetation) areas the greatest deposition of organic material occurs during the rainy season, while the greatest deposition in Cerrado and Caatinga areas occurs during the dry season (Delitti, 1995;Valenti et al, 2008).…”
Litterfall has a strong influence on biodiversity and on the chemical and physical characteristics of the soil. Its production can be quite variable over time and space, and can be influenced by both natural and anthropogenic factors. We evaluated litterfall production and its relationship with rainfall, species richness, and the densities of the arboreal vegetation. Thirty litter traps were constructed with 1.0 m 2 nylon mesh (1.0 mm) and randomly installed within a 2000 m × 500 m area of arboreal/shrub Caatinga (dryland) vegetation. Litter samples were collected monthly from November/2010 to June/2012, and the collected material was classified, dried, and weighted. Species richness and tree densities were determined by conducting phytosociological surveys in 20 m × 20 m plots surrounding each of the litter traps. The litterfall accumulation rate was 3.673 Mgha -1 yr -1 , similar to values from other seasonally dry tropical forests. Litterfall production was continuous, and principally accompanied the rainfall rate, but with a time interval of 2 to 3 months, with the greatest accumulation at the beginning of the dry season and the least during the rainy season.The different fractions of materials demonstrated distinct accumulation rates, with leaves being the principal category. Litterfall production was found to be related to tree density, but no link was found to species richness. The observed temporal heterogeneity of litterfall production demonstrated a strong link between rainfall and the dynamics of nutrient cycling in the semiarid region of Brazil.Keywords: Caatinga, spatial variability, temporal variability, necromass, neotropical region.Efeitos da precipitação e da vegetação sobre a produção de serapilheira em uma área do semiárido do nordeste brasileiro
ResumoA serapilheira exerce forte influência sobre a biodiversidade e as características físicas e químicas do solo. Sua produção pode ser bastante variável no tempo e no espaço e pode ser influenciada por fatores naturais e antropogênicos. Este estudo buscou avaliar a taxa de produção de serapilheira e a sua relação com a precipitação, riqueza de espécies e densidade da vegetação arbórea. No interior de uma área de 2000 m × 500 m foram sorteados aleatoriamente 30 pontos amostrais e em cada um deles instalado um coletor de aço de 1,0 m 2 . As coletas ocorreram mensalmente de novembro de 2010 a junho de 2012. O material coletado foi triado, secado e pesado. A riqueza de espécies e a densidade de árvores foram obtidas através de estudo fitossociológico em 30 parcelas de 20 m × 20 m. Foi registrada uma produção de serapilheira de 3,673 Mgha -1 yr -1 , taxa condizente com os valores encontrados para florestas tropicais sazonalmente secas. A produção de serapilheira foi contínua entre os meses, acompanhando principalmente o efeito tardio da precipitação (dois a três meses anteriores) e apresentou maior deposição no período do início da estação seca e menor no chuvoso. As frações do material apresentaram taxas de contribuição distintas, sendo a de fo...
“…Otherwise, on larger scales, both climatic variables and plant functional traits control it (Cornwell, 2008). The decomposition rate tends to increase from open to closed cerrado physiognomies (Cianciaruso et al, 2006;Valenti et al, 2008). If species occurring in different physiognomies present different traits, we may expect the functional diversity and decomposition rate to be correlated on a regional scale.…”
Community functioning may be affected by functional diversity, which measures the extent of complementarity in resource use. We tested whether there was a relationship between functional diversity of woody species and community functioning on a fine scale, using FD as a measure of functional diversity and litter decomposition rate as a surrogate for community functioning. We measured eight functional traits from a woodland cerrado community in southeastern Brazil. Then, we tested the correlation between FD and the decomposition rate taking into account differences in soil features and between decomposition rate and each trait separately. The decomposition rate was related to the aluminium and phosphorus concentration in soil, but not to FD, pointing out that functional diversity was not a good predictor of community functioning. There was a non-significant relationship between FD and the decomposition rate even when we considered each trait separately. Most studies in the relationships between biodiversity and community functioning on fine scales were carried out by experimental manipulation of diversity and in temperate regions. We carried out this fine scale study as a mensurative experiment and in a tropical savanna. Our findings indicated that the relationship between biodiversity and community functioning is not as straightforward as usually assumed.Keywords: litter decomposition, nutrient cycling, savanna, woodland cerrado.
Diversidade funcional, características edáficas e funcionamento de comunidade:teste em um sítio de cerrado
ResumoO funcionamento das comunidades deve ser afetado pela diversidade funcional, uma vez que esta mede a extensão da complementaridade no uso de recursos. Testamos se havia relação entre diversidade funcional das espécies arbóreas e o funcionamento da comunidade em escala fina, usando a FD como medida de diversidade funcional e a taxa de decomposição da serapilheira como indicadora do funcionamento. Medimos oito traços funcionais de plantas arbóreas em uma comunidade de cerrado no sudeste do Brasil. Testamos a correlação entre a FD e as taxas de decomposição, considerando diferenças nas variáveis edáficas e entre as taxas de decomposição e cada traço, separadamente. As taxas de decomposição se mostraram relacionadas com as concentrações de alumínio e fósforo, e não com a FD, indicando que a diversidade funcional não é uma boa preditora do funcionamento da comunidade. Não houve relação significativa entre FD e decomposição, mesmo quando consideramos cada traço separadamente. A maioria dos estudos sobre a relação entre diversidade e funcionamento em escalas finas foi desenvolvida por meio da manipulação experimental da diversidade e em regiões temperadas. Nossos resultados indicaram que a relação entre biodiversidade e funcionamento das comunidades não é tão direta como se assume usualmente.Palavras-chave: decomposição de serapilheira, ciclagem de nutrientes, savana, Cerrado sensu stricto.
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