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Ecophysiological strategies in nitrogen use in tree species of the Submontane Ombrophylous Dense and Seasonal Semideciduous Forest, Sao Paulo State

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Erico Fernando Lopes Pereira Silva
Total Authors: 1
Document type: Doctoral Thesis
Press: Campinas, SP.
Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
Defense date:
Examining board members:
Carlos Alfredo Joly; Ladaslav Sodek; Luiz Antonio Martinelli; Gabriela Bielefeld Nardoto; Eduardo Arcoverde de Mattos
Advisor: Carlos Alfredo Joly; Marcos Pereira Marinho Aidar

This work characterized the ecophysiological strategies nitrogen use in trees species in two forest types of the São Paulo State, the Submontane Ombrophylous Dense Forest, in the Carlos Botelho State Park (PECB) and the Seasonal Semideciduous Forest, in the Santa Genebra Municipal Reserve. The existence of relations between the primary metabolism of nitrogen with the sucessional category of 66 trees species in these forests was investigated. Moreover, in the Submontane Ombrophylous Dense Forest, it was verified if the ecophysiological of the three sucessional groups in function of the nitrogen use, was related with the seasonal availability of inorganic nitrogen in the soil. The results showed that the species use strategies to supply its nitrogen demand ahead of the variations of concentrations of this ion in soil between periods dry and wet and during the nitrogen pulse, occurring a proportionality of the acquisition, the transport and the assimilation. These strategies had been organized in groups of ecological succession, being proven that the pioneer species answer to the variations of the available soil nitrogen contents, over all in the form of nitrate. This group has a high capacity for nitrate assimilation, are able to respond to increased availability of soil nitrogen, have high leaf nitrogen contents and transport nitrogen predominantly as asparagine and nitrate and low leaf C:N. The late secondary species demonstrated to be little responsive to the seasonal soil nitrogen availability. Its levels of nitrate reductase activity had been very low in relation to the pioneer group, in the xylem sap amino acids had predominated as asparagine and arginina, low content of nitrate and leaf C:N was bigger in relation to the pioneer species. The early secondary species had shown average levels of nitrate reductase activity, in the xylem sap predominated transporting long distance as glutamine and arginine. This group has intermediate characteristics in the ecological succession, some species are next to the more responsive pioneers species and to the seasonal nitrogen variations in the soil while others early species are less responsive and more similar to the late secondary species. In the soil of the PECB, the nitrate and ammonium pulses had been correlated with the precipitation, evapotranspiration, temperature and with the content of organic matter. In the two forests, the ecophysiological variables of the selected species if condition the performance of strategies for the use of available inorganic nitrogen in soil, being able to be distributed in one continuum of ecophysiological answer of use of nitrogen between pioneers, early secondary species and late secondary species. The synthetic analysis of the sucessional groups evidenced that the trees species of Atlantic Forest have standardized strategies of leaf nitrogen assimilation and the application of the model of ecological succession in function of the nitrogen use in both the forest formations supplied more information and attend the necessity of advances in the determination of sucessional categories in tropical forests (AU)

FAPESP's process: 04/03647-6 - Use of nitrogen strategies in tree species in the forests of the State of São Paulo
Grantee:Erico Fernando Lopes Pereira da Silva
Support type: Scholarships in Brazil - Doctorate