Invasion by African grasses and restoration of open Cerrado formations: an approach by state-and-transition models

Author(s)

Gabriella de Faria Oliveira Damasceno Ribeiro

• Document type: Doctoral Thesis
• Press: Rio Claro. 2022-05-20.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências. Rio Claro
• Defense date: 2022-03-16
• Advisor: Alessandra Tomaselli Fidelis; Giselda Durigan

Abstract

Invasive alien species (IAS) represent one of the major challenges of the Anthropocene. The presence of invasive grasses is an obstacle to the conservation of tropical savannas, which are already threatened by the conversion of natural areas and, to a lesser extent, by misguided restoration initiatives. This thesis aimed to build a state-and-transition model regarding the degradation and restoration of tropical savannas. Specifically, we used field experiments to understand how the abundance of an invasive alien grass, Urochloa decumbens is related to changes in open Cerrado ecosystems. In addition, we also investigated how the IAS’s abundance can modulate the effects of prescribed burning in vegetation and functioning of these ecosystems. Fire experiments were implemented in Itirapina/SP and Brasília/DF where we sampled data at different levels of ecological organization: micro-habitat (luminosity, humidity, and temperature), individuals (specific leaf area), community (richness, diversity, and structure) and ecosystem (biomass accumulation, carbon flux and decomposition rate). Plots (25 m²) were established in each area representing Urochloa decumbens abundance gradients (0, 25, 50, 75 and 100% cover). In each area, three blocks were established, each one composed of a burnt gradient and another control. From the combination of information obtained in the field with those retrieved from the literature, we proposed a state-and-transition model composed of seven states, three stable states and four transient states. The degradation process resulting from the invasion by alien grasses can be reversed or minimized through management actions, capable of maintaining the system in states with less coverage by the IAS or less impacted by its presence. We hope that this model will serve as a basis for decision-making regarding the management of invasive alien grasses in tropical savannas. We believe that the science-based practice of applied ecology can help us overcome the challenges that humanity will face because of global changes. (AU)

• FAPESP's process: 18/09054-0 - Invasions by African grasses and Cerrado restoration: an approach by state-and-transition models
• Grantee: Gabriella de Faria Oliveira Damasceno Ribeiro
• Support Opportunities: Scholarships in Brazil - Doctorate