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Master's Dissertation
DOI
10.11606/D.64.2018.tde-18052018-101901
Document
Author
Full name
Marina Conte Peluci
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 2017
Supervisor
Committee
Piccolo, Marisa de Cassia (President)
Andrade, Cristiano Alberto de
Gonçalves, José Leonardo de Moraes
Title in Portuguese
Dinâmica do carbono e nitrogênio ao longo de uma sequência cronológica de florestas secundárias na bacia do rio Corumbataí
Keywords in Portuguese
Carbono 13
Ciclo do carbono
Ciclo do nitrogênio
Florestas tropicais
Pastagens
Solo
Uso do solo
Abstract in Portuguese
As mudanças no uso do solo, como por exemplo a remoção de áreas florestais para a implantação da agricultura e pecuária, promovem alterações no teor de matéria orgânica do solo. Em contrapartida, a regeneração natural surge como uma possibilidade do reestabelecimento parcial de funções ecológicas importantes, com destaque para o papel das florestas secundárias na redução do fluxo de gases atmosféricos, na influência da qualidade e quantidade da água, e no sequestro de carbono da atmosfera e estocagem no solo. O objetivo deste trabalho foi avaliar o comportamento do carbono e do nitrogênio no solo ao longo da sequência cronológica de florestas secundárias, comparando-as com floresta madura e pastagens no município de Rio Claro (SP). Com o auxílio de imagens aéreas (dos anos de 1978, 1995, 2000 e 2008) foram selecionadas 15 parcelas com 900 m2 cada, as quais consistiram em uma sequência temporal de florestas secundárias regeneradas sob pastagem (apresentando 8 a 16 anos (FS12), 21 a 38 anos (FS30) e 38 a 54 anos (FS46)), além de floresta "fonte" (floresta estacional semidecidual) com mais de 55 anos (FF) e pastagem em uso há mais de 50 anos (PA50). O solo da área de estudo é classificado como Argissolo de textura média. As concentrações e estoques de carbono (C) e nitrogênio (N) e os valores isotópicos de C (?13C) foram analisados na serapilheira e nas camadas de 0-10, 10-20 e 20-30 cm do solo. A análise de ?13C indicou presença do sinal isotópico oriundo de vegetação C3 já nos primeiros 12 anos de regeneração, representando 60% do C presente no solo (proveniente da FF e da FS12). Na área de pastagem foi constatada a presença de carbono remanescente da floresta nativa (C3), correspondendo por 30% do carbono total. A análise de componentes principais definiu os agrupamentos de acordo com as áreas de estudo, além de correlacionar negativamente os estoques de carbono e nitrogênio e os teores de areia. As florestas secundárias apresentaram estoques de carbono e nitrogênio na serapilheira próximos à floresta fonte (1,8 Mg C ha-1 e 0,10 Mg N ha-1). Os estoques de C e N no solo (0-30 cm) foram maiores na floresta fonte (74,1 Mg C ha-1 e 7,6 Mg N ha-1), ocorrendo brusca redução (40%) na conversão para pastagem (41,4 Mg C ha-1 e 4,7 Mg N ha-1). Além disso, as áreas de regeneração não diferiram da área de pastagem quanto aos estoques de carbono e nitrogênio no solo
Title in English
Carbon and nitrogen dynamics along a chronological sequence of secondary forests in the Corumbatai river basin
Keywords in English
Carbon 13
Carbon cycle
Grassland
Nitrogen cycle
Soil
Soil use
Tropical forests
Abstract in English
Changes in soil use, such as the removal of forest areas for the implantation of agriculture and livestock, promote changes in soil organic matter content. Due to this imbalance between the inputs and outputs of plant material in the system the MOS dynamics will be changed, affecting the ecosystem as a whole. On the other hand, natural regeneration appears as a possibility for the partial reestablishment of important ecological functions, with emphasis on the role of secondary forests in the reduction of the flow of atmospheric gases, the influence of water quality and quantity, and sequestration of carbon from the atmosphere and storage in the soil. The objective of this work was to evaluate the behavior of carbon and nitrogen in the soil along the chronological sequence of secondary forests, comparing them with old growth forest and pastures in Rio Claro (SP). Fifteen plots with 900 m2 each were selected using aerial images (from 1978, 1995, 2000 and 2008), which consisted of a temporal sequence of regenerated secondary forests under pasture (8 to 16 years old (FS12) 21 to 38 years old (FS30) and 38 to 54 years old (FS46)), as well as an old growth forest (seasonal semideciduous forest) with more than 55 years (FF) and pasture in use for more than 50 years (PA50). The soil of the study area is classified as Argissolo. with medium texture. The concentrations and stocks of carbon (C) and nitrogen (N) and the isotopic values of C (?13C) were analyzed in the litter and in the layers of 0-10, 10-20 and 20-30 cm of the soil. The analysis of ?13C indicated the presence of the isotopic signal from C3 vegetation already in the first 12 years of regeneration, representing 60% of the C present in the soil (coming from FF and FS12). In the pasture area, the remaining carbon of the native forest (C3) was observed, corresponding to 30% of the total carbon. The principal components analysis defined the groupings according to the study areas, in addition to negatively correlating the carbon and nitrogen stocks and the sand contents. Secondary forests presented carbon and nitrogen stocks in the litter approximate to the old growth forest (1,8 Mg C ha-1 and 0,10 Mg N ha-1). C and N stocks in the soil (0-30 cm) were higher in the old growth forest (74,1 Mg C ha-1 and 7,6 Mg N ha-1), with an abrupt reduction (40%) in conversion to pasture (41,4 Mg C ha-1 and 4,7 Mg N ha-1). In addition, the regeneration areas did not differ from the pasture area for carbon and nitrogen stocks in the soil
 
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Publishing Date
2018-05-22
 
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