Allelopathy or physical restriction? Influence of litter on the regeneration of native species in eucalyptus plantations

• Grant number: 21/09477-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2022
• End date: March 31, 2023
• Field of knowledge: Agronomical Sciences - Forestry Resources and Forestry Engineering - Nature Conservation
• Principal Investigator: Pedro Henrique Santin Brancalion
• Grantee: Guilherme Almeida Melman
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Associated research grant: 18/18416-2 - Understanding restored forests for benefiting people and nature - NewFor, AP.BTA.TEM

Abstract

Allelopathy has been identified as the main cause of the lack of regeneration of native vegetation in eucalyptus plantations, directly affecting seed germination. However, there is not enough evidence to affirm that the allelopathic effect of eucalyptus is the most determining factor. This project aims to evaluate the influence of the litter layer on the regeneration of native tree species in the eucalyptus understory, seeking to isolate the effect of physical and chemical restrictions of the litter. For this, 33 plots located in the E.E.C.F of Itatinga and Anhembi will be installed to collect data on natural regeneration and litter samples. The litter samples will be characterized in terms of nutrient concentration, dry biomass, lignin content, C/N ratio, and water retention. In addition, germination tests will also be carried out, under controlled and field conditions, and decomposition experiments with litter bags. In the field germination tests, 10 native tree species typical of understory will be tested, 5 recalcitrant and 5 orthodox, submitted to two treatments (with and without litter cover), both in eucalyptus and native forest areas. In the laboratory, two experimental designs will be carried out: germination below and above the litter layer. In each of them, a model species will be conditioned to 3 treatments (E. urophylla litter, C. citriodora and a mixture of natives) with 4 levels (thickness of 0, 2, 4, 6, and 8 cm).(AU)