Decrease in species richness and diversity, and shrub encroachment in Cerrado grasslands: A 20 years study

Abstract

Question:The Cerrado is a global biodiversity hotspot, highly threatened by changes in land use. Alterations in species composition and the colonization of Cerrado grasslands by woody species can lead to long-term changes in these communities. In this study, we investigated changes over 20 years in three grassland areas, in terms of species richness and diversity and growth-form cover, as well as the effects of shrub and grass encroachment on species richness.Location: Cerrado Brazilian savanna, moist grassland and dry shrub grassland. Areas under low and high anthropogenic pressure.Methods: Plant species composition and cover were sampled on seven occasions between the years 2000 and 2020, in permanent line-transects. We compared plant cover, richness, diversity and growth-form cover between the periods for each area.Next, we developed mixed-effect linear models to test whether species richness in grasslands at the latest sampling event was altered by species representing 70% of the species cover at this time.Results: Grasslands located in areas under higher anthropogenic pressure presented reduced richness and diversity, and cover concentrated on a few species of shrubs and large tussock grasses. Moist grassland undergoing encroachment by the native shrub Trembleya parviflora had lost over 50% of its diversity since encroachment. In the same area, a shrub grassland undergoing encroachment by native shrub Raulinoreitzia tremula, three native grass species and one exotic grass presented significantly reduced species richness. The moist grassland in an area under low anthropogenic pressure showed a reordering of the species cover over time, but a decrease in species richness. Conclusion:We observed changes in plant richness, diversity, cover, composition and growth-form cover over a period of 20 years in grassland communities. We found, however, different trajectories in the three grassland areas sampled, mainly due to the encroachment of a few species, leading to floristic homogenization in grasslands located in areas under high anthropogenic pressure.

Termites are key drivers of short‐term deadwood decay in Neotropical Cerrado across vegetation types

“…(2022) investigation of temperature and precipitation. Additionally, our study improves the understanding of carbon dynamic changes in an ecosystem under vegetation suppression, mainly in open areas affected by encroachment of woody vegetation (de Souza et al., 2022; Rosan et al., 2019).…”

“…Our study suggests vegetation cover is an important determinant of the termite role in wood decay; the importance of vegetation cover should be examined at global scales similar to the Zanne et al ( 2022) investigation of temperature and precipitation. Additionally, our study improves the understanding of carbon dynamic changes in an ecosystem under vegetation suppression, mainly in open areas affected by encroachment of woody vegetation (de Souza et al, 2022;Rosan et al, 2019).…”

Woody Plant Encroachment in a Seasonal Tropical Savanna: Lessons about Classifiers and Accuracy from UAV Images

“…Its fruits contain many tiny seeds that are dispersed by the wind in August and September. In the Federal District, rapid landscape transformation is occurring because of dense T. parviflora colonization, resulting in the loss of the native herbaceous community in wetlands [23].…”

“…The accuracy of classifying B. retusa (wood) was less influenced by season but this was still high, which was expected because the leafless wood canopy tends to maintain its spectral signature regardless of water availability. This is a positive result for managing and monitoring woody encroachment, especially in wet grasslands, because the wet season is the most suitable period for floristic surveys [23,82] and monitoring of water dynamics [83][84][85].…”

Interactive roles of fire seasons and biological invasions in the short‐term dynamics of tropical savannas

“…In tropical savannas, for example, environmental changes have the potential to alter fire regimes, and consequently, community composition (Pamplona, 2019; Kelly et al., 2020). Beside wildfires, biological invasions have become one of the greatest threats to biodiversity (de Souza et al., 2022; Damasceno & Fidelis, 2023). In the Cerrado, African grasses of the genus Urochloa (brachiaria), such as Urochloa brizantha (Hochst.…”