Advance of Urochloa decumbens (Stapf) R.D. Webster (Poaceae) on remaining native forest in the Serra da BODOQUENA NATIONAL PARK

Abstract

The replacement of native forest by exotic grasses for pasture formation is a process that involves habitat destruction followed by the introduction of invasive alien species. The Serra da Bodoquena National Park covers an area of 77,021.58ha, comprising natural forests and remnants of abandoned pastures, which represent a threat to local biodiversity conservation. This study analyzed the dynamics of Urochloa decumbens–dominated matrix on remnants of native Deciduous Seasonal Forest within the Park, over 35 years, using satellite images, evaluating natural regeneration trend. The Urochloa matrix covers 1,268.9 (36.9%) of the 3,434.50 hectares study area. Our results indicate that the Urochloa matrix expanded over the native forest remnants, likely due to the occurrence of fire close to the forest edges, which may help natural regeneration failing. 8 months after a fire in 2013, the area of the grass-dominates matrix was found to replace 203.1 hectares over the forest. In this context, restoration actions are demanded, especially those that target fire control.

Tree diversity in riparian forests immersed in a pasture with Urochloa decumbens (Stapf) R.D. Webster (Poaceae) grass under domain of the Atlantic Forest, Brazil

“…At these forests the richest botanical family was Fabaceae, followed by Euphorbiaceae, Sapindaceae and Solanaceae families, represented mostly by common species in the early stages of secondary succession in Atlantic Forests biome (Aide et al, 2000;Baylão-Junior et al, 2011;Guareschi et al, 2014;Scervino and Torezan, 2015;Scervino and Pereira, 2021) and also dispersed by anemochoric or zoochoric syndromes, in this case, mostly by birds and bats tolerant to open areas (Aide et al, 2000;Yang et al, 2010;Baylão-Junior et al, 2011;De Oliveira et al, 2020;Gutiérrez-Chacón, Valderrama-a and Klein, 2020;Turunen et al, 2021). This may be related to an intense edge effect that alters the micro-climate conditions and affect vegetation diversity on these riparian forests, favoring the establishment of species tolerant to high luminosity due an elevated canopy openness and climate stress (Puerta, 2002;Esquivel et al, 2008;Griscom, Griscom and Ashton, 2009;Yang et al, 2010;Massad et al, 2011;Paolino et al, 2018;Turunenet al, 2019;Turunen et al, 2021).…”

“…On the other hand, species richness is not influenced by the width of the riparian forest, suggesting that only species more tolerant to stress, such as a great amplitude range of humidity and temperature of the air and soil, a compact soil and a high herbivory tax due to cattle grazing, are able to colonize these narrow riparian forest strips surrounded by U. decumbens pastures (Holl, 1999;Holl, 2002;Puerta, 2002;Griscom, Griscom and Ashton, 2009;Leitão, Marques and Ceccon, 2010;Massad et al, 2011;Guareschi et al, 2014;Brito et al, 2017;De Oliveira et al, 2020).…”

“…The U. decumbens cover inside the riparian forests is different on the studied watercourses, and the lagers forests present lower grass cover. This may be related to shadow micro-sites that reduce the luminosity on larger riparian forests, which can affect the U. decumbens growth under more shadowed conditions (Holl, 2002;Davis et al, 2005;Esquivel et al, 2008;Scervino and Torezan, 2015;Feld et al, 2018;Burdon et al, 2020;De Oliveira et al, 2020).…”

“…Relationship among grass cover and woody species was observed in the abundance and density of species, with high negative correlations with native species. U. decumbens is known by having an efficient seed dispersal mechanism, a high invasive potential and aggressive behavior compared to native Atlantic Forest species on the exploration of water, nutrients and light (Ziller, 2001;Boddey et al, 2004;Barbosa, Pivello and Meirelles, 2008;Griscom, Griscom and Ashton, 2009;Massad et al, 2011;Scervino and Torezan, 2015;De Oliveira et al, 2020). Also, the high production of aerial biomass and the formation of an intricate root web system on the superficial soil horizon can diminish forest seeds germination and the plant establishment, and it can increase the risk of fire on forests with higher grass cover (Marod et al, 2002;Marod et al, 2004;Ribeiro et al, 2006;Guareschi et al, 2014;Cury et al, 2020;De Oliveira et al, 2020;Xavier et al, 2021).…”

“…Currently, Uroclhoa genera is widespread on pasture fields in many regions in Brazil and has invaded natural areas in different biomes, altering vegetation structure, composition and acting on the ecosystem resilience (Boddey et al, 2004;Ferreira et al, 2016;de Oliveira et al, 2020). In this context, this study aimed to evaluate the relationships among grass cover and arboreal species diversity in watercourses surrounded by a pasture dominated with Uroclhoa decumbens (Stapf) R.D.…”