Knowledge Resource Center for Ecological Environment in Arid Area
| Soil engineering by macroinvertebrates: controls on soil organic matter storage across land use change Macroinvertebrados e os processos de engenharia do solo: controles sobre a estocagem de matéria orgânica do solo em áreas com mudanças no uso da terra | |
| André Luiz Custódio Franco | |
| 出版年 | 2015 |
| 学位授予单位 | Universidade de São Paulo, Agronomia (Solos e Nutrição de Plantas), USP, BR |
| 英文摘要 | Globally land use change (LUC) with increasing in land use intensity has led to a decrease in soil organic matter (SOM). The reduction of soil C stock across LUC has been accompanied by a destabilization of soil structure and increases the soil erosion susceptibility. The destabilized soil structure is also concomitant with a loss of soil biodiversity and in particular, soil macroinvertebrate community. The focus of this dissertation is the effect of LUC with increasing in land use intensity on soil macrofauna, aggregation and SOM allocation. We hypothesized that LUC reduces soil macrofaunal biodiversity and consequently decreases soil engineering processes, resulting in destabilization of soil structure and impairing the ability of soil to physically protect SOM from decomposition inside stable aggregates, finally leading to depleted SOC stocks across LUC. In order to test these hypotheses, we conducted a field survey in 3 chronosequences of land use comprising native vegetation (NV), pasture (PA), and sugarcane crop (SC) in Central-Southern Brazil. This land use sequence provides a gradient of land use intensity and is projected to add 6.4 Mha of new sugarcane areas in Brazil by 2021. At each sampling point soil blocks of 25 X 25 cm and 5 x 5 cm to 10 cm depth were simultaneously collected from 0-10 cm, 10-20 cm, and 20-30 cm soil layers, for macrofauna isolation and aggregate fractionation, respectively. Within a radius of 6 meters around each sampling point, 12 subsamples were also collected from the same soil layers, and combined for total soil C and N concentration. An average reduction of 89% in the density of the soil macrofaunal community was observed when SC replaces PA, and a loss of 39% in the diversity of macrofauna groups. Our findings showed that, over a range of soil textures (16 - 66% clay), such biodiversity loss was strongly correlated with the destabilization of soil structure across LUC, whereas soil texture was not so. These observations consistently indicate that the abundance of detritivore soil animals, especially earthworms and termites, may be a significant predictor of soil structure transformations across LUC in tropical environments. Moreover, the sharp reduction in the abundance of earthworms was strongly positively correlated with the decrease in intra macroaggregate-associated C. As a result, after more than 20 years of sugarcane crop there were losses of 40 and 35% of C and N stocks, respectively, resulting in a rate of C emission of 1.3 Mg ha-1 yr-1. This C loss primarily occurred in the macroaggregate-associated C, as a result of the faster macroaggregate turnover under SC. In summary, the results presented here provide a mechanistic explanation as to why there is soil C depletion when increasing land use intensity in tropical soils: the huge reduction in the abundance of soil engineering invertebrates after LUC impair the ability of soil to physically protect SOM from decomposition inside stable aggregates, and therefore it is a primary mechanism controlling the soil C stocks\' depletion across LUC. Globalmente mudanças no uso da terra (MUT) com o aumento da intensidade de uso do solo têm levado a uma diminuição da matéria orgânica do solo (MOS). A redução do estoque de C do solo após MUT tem sido acompanhada por uma desestabilização da estrutura do solo e aumento da susceptibilidade a erosão. A desestabilização da estrutura também é concomitante com a perda da biodiversidade do solo e, em particular, da comunidade de macroinvertebrados do solo. O foco deste trabalho é o efeito de MUT com aumento na intensidade de uso do solo sobre a macrofauna do solo, agregação e alocação da MOS. Nossa hipótese é que MUT reduz a diversidade da macrofauna do solo e, conseqüentemente, diminui os processos de engenharia de solo, resultando na desestabilização da estrutura do solo e prejudicando a capacidade do solo para proteger fisicamente a MOS da decomposição dentro de agregados estáveis, finalmente l |
| 英文关键词 | Agrega??o Biodiversidade do solo Estoques de carbono Estrutura do solo Expans?o da cana-de-a?úcar Funcionamento de ecossistemas Macrofauna Aggregation Carbon storage Ecosystem functioning Macrofauna Soil biodiversity Soil structure Sugarcane expansion |
| 语种 | 其他 |
| URL | http://www.teses.usp.br/teses/disponiveis/11/11140/tde-26052015-165800 |
| 来源机构 | Universidade de São Paulo, Agronomia (Solos e Nutrição de Plantas), USP, BR |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/249245 |
| 推荐引用方式 GB/T 7714 | André Luiz Custódio Franco. Soil engineering by macroinvertebrates: controls on soil organic matter storage across land use change Macroinvertebrados e os processos de engenharia do solo: controles sobre a estocagem de matéria orgânica do solo em áreas com mudanças no uso da terra[D]. Universidade de São Paulo, Agronomia (Solos e Nutrição de Plantas), USP, BR,2015. |
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