Residue removal in eucalyptus forests: influence on the fungal community and soil phosphorus cycling

Author(s)

Maiele Cintra Santana

• Document type: Doctoral Thesis
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2024-06-06

Examining board members

Elke Jurandy Bran Nogueira Cardoso; Joice Andrade Bonfim; George Rodrigues Lambais; Tsai Siu Mui

• Advisor: Elke Jurandy Bran Nogueira Cardoso

Abstract

Forest residues play a fundamental role in the dynamics of the chemical, physical and biological properties of the soil, such as carbon storage, protection against erosion and the provision of nutrients for microbial metabolism. The option of removing forest residues to generate energy seems to go against the minimum cultivation system, which represents a forestry practice that is beneficial for the health of the soil and trees. There are no records of studies evaluating the influence of consecutive removal of forest residues on the fungal community in tropical soil conditions. The study of this gap is extremely important, as the impact on the fungal community caused by the removal of these residues can influence levels of the phosphorus (P) cycle in the soil, increasing the need to apply phosphate mineral fertilizers. In this way, a long-term experiment was evaluated, installed with various levels of residue removal using a Eucalyptus grandis culture as a model. We characterized litter, soil and rhizospheric soil to assess the total and mycorrhizal fungal community with the aim of identifying important parameters associated with P cycling. Our general hypothesis is that consecutive removal of residues reduces the diversity and key functions of the community of fungi, altering P cycling in the soil. The experiment was installed in 2004 and reinstalled in 2012 (first and second rotations, respectively), at the Itatinga Experimental Forest Sciences Station (ESALQ-USP) in a Yellow Oxisol, typically dystrophic, with a medium-sandy texture. In this case, samples of litter, soil and rhizospheric soil were collected in the 0-10 cm depth layer of the soil in two experiments during the year (dry and rainy). Chemical and physical characterization analyzes of the samples were carried out, as well as microbialenzymatic activity. The taxonomic profile of the total fungal community and AMF were evaluated through large-scale sequencing of the ITS and 18S regions respectively. It is concluded from these results that residue removal has significant effects on the cycling of phosphorus and other nutrients, as well as on the structuring of the fungal community, and may have positive consequences on forest management and productivity. (AU)

• FAPESP's process: 18/20553-8 - Residues removal in eucalyptus forests: influence on the fungi community and phosphorus cycling in soil
• Grantee: Maiele Cintra Santana
• Support Opportunities: Scholarships in Brazil - Doctorate