1. Tropical savannas are known for the fire-prone ecosystems, yet, riparian evergreen forests are another important landscape feature. These forests usually remain safe from wildfires in the wet riparian zones. With global changes, large wildfires are now more frequent in savanna landscapes, exposing riparian forests to unprecedented impact. 2. In 2017, a large wildfire spread across the Chapada dos Veadeiros National Park, an iconic UNESCO site in central Brazil, raising concerns about its impact on the fire-sensitive ecosystems. By combining remote sensing analysis of Google Earth images (2003-2019) with detailed field information from 36 sites, we assessed wildfire impacts on riparian forests. For this, we measured the structure of trees, saplings and herbaceous plants, as well as topsoil variables. 3. Since 2003, all riparian forests had canopy cover above 90%, but after 2017, canopy cover dropped to 20% in some forests, indicating large variation in wildfire damage. A closer look in the field revealed that, on average, the wildfire killed 52% of adult trees and 87% of tree saplings in flooded forests. In non-flooded forests, impacts on adult trees were negligible, but fire killed 75% of tree saplings. Opportunistic vines and the invasive grass Melinis minutiflora were already present in severely disturbed flooded forests. In all forests, impacts on many ecosystem variables were related to canopy damage, a variable measurable from satellite. Overall, seasonally flooded riparian forests were the most severely impacted, possibly due to the relatively thinner barks of their trees.
1. Around 40% of the original Brazilian savanna territory is occupied by pastures dominated by fast-growing exotic C 4 grasses, which impact ecosystem nutrient cycling. The restoration of these areas depends on the re-establishment of soil processes.2. We assessed how restoration of abandoned pastures through direct seeding of native species and land-management practices (burning and ploughing) affect soil nutrient cycling dynamics compared with native savannas. We compared the activity of soil enzymes related to carbon, nitrogen (N) and phosphorus (P) cycling as well as soil microbial biomass and soil chemical properties (pH and the concentration of N, P, potassium [K] and soil organic matter) among abandoned pastures, native savanna and restored areas.3. Abandoned pastures had faster nutrient turnover than native savanna, dominated by slow-growing native species. This pattern was evident from the overall higher biomass-specific enzyme activities in abandoned pastures than in native savanna. Compared with native savanna, restored areas had similar levels of soil enzyme activities, but lower microbial biomass and soil organic matter. The low enzyme activity in restored areas was likely related to a reduced soil organic carbon concentration due to practices such as burning and ploughing, rather than the restoration of plant-soil feedback. The lower immobilization of nutrients in microbial biomass and lower retention of nutrients in restored areas, compared
Gramíneas invasoras introduzidas para pastagem são um grande desafio para conservação e restauração do Cerrado. Este grupo é constituído principalmente por espécies de rápido crescimento e estratégias aquisitivas que se desenvolvem rapidamente em solos ricos em nutrientes. A modificação do solo do Cerrado, retirando suas características típicas de baixo pH e baixa disponibilidade nutricional, facilita a invasão. Por isso, alterações nas condições edáficas de áreas degradadas, buscando tornar o solo mais próximo do solo nativo do Cerrado, podem contribuir para o sucesso de plantas nativas. Dessa forma, buscamos responder como a acidificação do solo altera o desenvolvimento de umas gramínea invasora e uma nativa. Para isso, semeamos as espécies em solo acidificado por sulfato ferroso e avaliamos a biomassa aérea e área específica foliar das espécies após três meses de crescimento. Observamos que a acidificação teve um maior efeito na redução do crescimento da gramínea nativa devido ao fato desta ser uma espécie de estratégia aquisitiva, diferentemente de outras espécies nativas abundantes no Cerrado.
Resumo O domínio cerrado é considerado um "hotspot" de biodiversidade e sua integridade e diversidade de espécies estão fortemente ameaçadas por mudanças de uso da terra em grande escala e pela invasão de espécies de gramíneas de origem africana. As gramíneas africanas têm o potencial de afetar funções ecossistêmicas, alterando a produtividade, estrutura trófica, o microclima, a disponibilidade de recursos e as interações competitivas. A alta disponibilidade de nutrientes no solo pode favorecer a invasão de espécies exóticas de rápido crescimento, superando espécies nativas do Cerrado. O objetivo desse projeto é entender a influência da alcalinização do solo na capacidade competitiva de uma gramínea exótica invasora (Urochloa decumbens) e uma gramínea nativa. Com o tratamento de calagem do solo, buscamos aumentar a disponibilidade de nutrientes para favorecer o desenvolvimento de U. decumbens em detrimento do Andropogon fastigiatus, gramínea nativa muito abundante em áreas em processo de restauração.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.