Crescimento de plantulas da especie invasora Calotropis procera em solos de campos rupestres ferruginosos e floresta seca sazonal

The present study evaluated the growth, biomass allocation and nutrient content in seedlings of the invasive and exotic especies Calotropis procera (Aiton) W.T. Aiton (Apocynaceae), cultured in greenhouse, in soils from two different ecosystems: ironstone rupestrian fields (Canga) of Brumadinho, Minas Gerais; and seasonally dry forest (Caatinga), of Serra Talhada, Pernambuco. Seedlings from the Canga treatment were significantly higher in concern to stem length, leaf biomass and total biomass. In respect to nutrient content there were higher phosphorus, iron and zinc levels in the seedlings from the Canga treatment. The iron accumulation indicates the capacity of C. procera to tolerate high levels of iron, which is characteristic of Canga soils. In the Caatinga treatment there was a higher root/ shoot ratio and a higher potassium accumulation in the plant tissues. The obtained results suggest that C. procera displays a good adaptation to the edaphic conditions of the Canga treatment, which indicates an invasive potential towards the Canga ecosystem. Key words: Caatinga, Calotropis procera, Canga, early growth, invasion.O presente estudo avaliou o crescimento, a alocação de biomassa e os teores de nutrientes em plântulas da espécie exótica e invasora Calotropis procera (Aiton) W.T. Aiton (Apocynaceae), cultivadas em casa de vegetação, em solos provenientes de dois ecossistemas distintos: campo rupestre ferruginoso (Canga, Brumadinho, Minas Gerais) e floresta seca sazonal (Caatinga, Serra Talhada, Pernambuco). Plântulas do tratamento Canga foram significativamente maiores em relação ao comprimento do caule, biomassa de folhas e biomassa total. Em relação aos teores de nutrientes, houve maior teor de fósforo, ferro e zinco nos tecidos de plântulas do tratamento Canga. O acumulo de ferro indica a capacidade de C. procera em tolerar os altos teores de ferro característicos dos solos de Canga. No tratamento Caatinga, houve uma maior razão raiz-ramo e maior acúmulo de potássio em seus tecidos. Os resultados obtidos sugerem que C. procera demonstra boa adaptação às condições dos solos do tratamento Canga, indicando um potencial para invasão no ecossistema de Canga. Palavras-chave: Caatinga, Calotropis procera, Canga, crescimento inicial, invasão biológica

Calotropis procera: um levantamento preliminar sobre as suas capacidades de fitoextração no Brasil

Calotropis procera (Apocynaceae) is a non-native species that has its origin in Africa and Asia, but was introduced into the northeastern region of Brazil in the beginning of last century. In some areas, the dry biomass of C. procera is used as animal feed. However, previous studies indicated that the species is capable of accumulating many chemical elements. On the other hand, it could also mean that this species may be used for phytoremediation. Hence, we used neutron activation analysis, k0-method, to test the capability of the leaves of C. procera to accumulate trace elements. The study was carried out in two distinct areas (polluted and non-polluted) in the State of Pernambuco, Brazil. Our results indicate that new elements can be added to the list of elements taken up by C. procera, thus contributing to the understanding of the biology of this plant species as an accumulator of trace elements. Some elements, such as Ba and Sr, have higher concentrations in the non-polluted areas than in polluted areas. Thus, the presence of many trace elements in C. procera indicates that its use as animal feed should be viewed with extreme caution. However low levels of these trace elements in C. procera do not indicate that this species is a hyper-accumulator plant.Key words: phytoremediation, biological invasion, invasive species, Pernambuco.Calotropis procera (Apocynaceae) é uma espécie exótica originária da África e Ásia tropical, introduzida na região nordeste do Brasil no início do século passado. Em algumas regiões do Brasil e do mundo, a biomassa seca de C. procera é utilizada como alimento forrageiro para animais. Entretanto, muitos estudos indicam que essa espécie é capaz de acumular diversos elementos químicos. Isso pode significar que a espécie também pode ser utilizada em processos de fitorremediação. Dessa forma, foi realizada uma análise de ativação neutrônica, método k0, para testar a capacidade das folhas de C. procera acumularem elementos-traço. O estudo foi realizado em duas áreas distintas (poluídas e não poluídas) no estado de Pernambuco, Brasil. Nossos resultados indicam que novos elementos podem ser adicionados à lista de elementos-traço absorvidos por C. procera, contribuindo para o entendimento da biologia dessa espécie como acumuladora de elementos-traço. Alguns destes, tais como Ba e Sr, ocorreram em maiores concentrações em áreas não-poluídas em comparação com áreas poluídas. Dessa forma, o uso de C. procera como ração animal deve ser vista com extrema cautela. Entretanto, as baixas concentrações desses elementos-traço não sugerem que C. procera seja uma hiperacumuladora.Palavras-chave: fitorremediação, invasão biológica, espécie invasora, Pernambuco

Biodiversity recovery of Neotropical secondary forests

Old-growth tropical forests harbor an immense diversity of tree species but are rapidly being cleared, while secondary forests that regrow on abandoned agricultural lands increase in extent. We assess how tree species richness and composition recover during secondary succession across gradients in environmental conditions and anthropogenic disturbance in an unprecedented multisite analysis for the Neotropics. Secondary forests recover remarkably fast in species richness but slowly in species composition. Secondary forests take a median time of five decades to recover the species richness of old-growth forest (80% recovery after 20 years) based on rarefaction analysis. Full recovery of species composition takes centuries (only 34% recovery after 20 years). A dual strategy that maintains both old-growth forests and species-rich secondary forests is therefore crucial for biodiversity conservation in human-modified tropical landscapes. Copyright © 2019 The Authors, some rights reserved

Wet and dry tropical forests show opposite successional pathways in wood density but converge over time

Tropical forests are converted at an alarming rate for agricultural use and pastureland, but also regrow naturally through secondary succession. For successful forest restoration, it is essential to understand the mechanisms of secondary succession. These mechanisms may vary across forest types, but analyses across broad spatial scales are lacking. Here, we analyse forest recovery using 1,403 plots that differ in age since agricultural abandonment from 50 sites across the Neotropics. We analyse changes in community composition using species-specific stem wood density (WD), which is a key trait for plant growth, survival and forest carbon storage. In wet forest, succession proceeds from low towards high community WD (acquisitive towards conservative trait values), in line with standard successional theory. However, in dry forest, succession proceeds from high towards low community WD (conservative towards acquisitive trait values), probably because high WD reflects drought tolerance in harsh early successional environments. Dry season intensity drives WD recovery by influencing the start and trajectory of succession, resulting in convergence of the community WD over time as vegetation cover builds up. These ecological insights can be used to improve species selection for reforestation. Reforestation species selected to establish a first protective canopy layer should, among other criteria, ideally have a similar WD to the early successional communities that dominate under the prevailing macroclimatic conditions

Biomass resilience of Neotropical secondary forests

Land-use change occurs nowhere more rapidly than in the tropics, where the imbalance between deforestation and forest regrowth has large consequences for the global carbon cycle. However, considerable uncertainty remains about the rate of biomass recovery in secondary forests, and how these rates are influenced by climate, landscape, and prior land use. Here we analyse aboveground biomass recovery during secondary succession in 45 forest sites and about 1,500 forest plots covering the major environmental gradients in the Neotropics. The studied secondary forests are highly productive and resilient. Aboveground biomass recovery after 20 years was on average 122 megagrams per hectare (Mg ha-1), corresponding to a net carbon uptake of 3.05 Mg C ha 1 yr-1, 11 times the uptake rate of old-growth forests. Aboveground biomass stocks took a median time of 66 years to recover to 90% of old-growth values. Aboveground biomass recovery after 20 years varied 11.3-fold (from 20 to 225 Mg ha-1) across sites, and this recovery increased with water availability (higher local rainfall and lower climatic water deficit). We present a biomass recovery map of Latin America, which illustrates geographical and climatic variation in carbon sequestration potential during forest regrowth. The map will support policies to minimize forest loss in areas where biomass resilience is naturally low (such as seasonally dry forest regions) and promote forest regeneration and restoration in humid tropical lowland areas with high biomass resilience. © 2016 Macmillan Publishers Limited. All rights reserved.Additional co-authors: Saara J. DeWalt, Juan M. Dupuy, Sandra M. Durán, Mario M. Espírito-Santo, María C. Fandino, Ricardo G. César, Jefferson S. Hall, José Luis Hernandez-Stefanoni, Catarina C. Jakovac, André B. Junqueira, Deborah Kennard, Susan G. Letcher, Juan-Carlos Licona, Madelon Lohbeck, Erika Marín-Spiotta, Miguel Martínez-Ramos, Paulo Massoca, Jorge A. Meave, Rita Mesquita, Francisco Mora, Rodrigo Muñoz, Robert Muscarella, Yule R. F. Nunes, Susana Ochoa-Gaona, Alexandre A. de Oliveira, Edith Orihuela-Belmonte, Marielos Peña-Claros, Eduardo A. Pérez-García, Daniel Piotto, Jennifer S. Powers, Jorge Rodríguez-Velázquez, I. Eunice Romero-Pérez, Jorge Ruíz, Juan G. Saldarriaga, Arturo Sanchez-Azofeifa, Naomi B. Schwartz, Marc K. Steininger, Nathan G. Swenson, Marisol Toledo, Maria Uriarte, Michiel van Breugel, Hans van der Wal, Maria D. M. Veloso, Hans F. M. Vester, Alberto Vicentini, Ima C. G. Vieira, Tony Vizcarra Bentos, G. Bruce Williamson, Danaë M. A. Rozendaa

Data from: Biomass resilience of Neotropical secondary forests

Land-use change occurs nowhere more rapidly than in the tropics, where the imbalance between deforestation and forest regrowth has large consequences for the global carbon cycle1. However, considerable uncertainty remains about the rate of biomass recovery in secondary forests, and how these rates are influenced by climate, landscape, and prior land use2, 3, 4. Here we analyse aboveground biomass recovery during secondary succession in 45 forest sites and about 1,500 forest plots covering the major environmental gradients in the Neotropics. The studied secondary forests are highly productive and resilient. Aboveground biomass recovery after 20 years was on average 122 megagrams per hectare (Mg ha−1), corresponding to a net carbon uptake of 3.05 Mg C ha−1 yr−1, 11 times the uptake rate of old-growth forests. Aboveground biomass stocks took a median time of 66 years to recover to 90% of old-growth values. Aboveground biomass recovery after 20 years varied 11.3-fold (from 20 to 225 Mg ha−1) across sites, and this recovery increased with water availability (higher local rainfall and lower climatic water deficit). We present a biomass recovery map of Latin America, which illustrates geographical and climatic variation in carbon sequestration potential during forest regrowth. The map will support policies to minimize forest loss in areas where biomass resilience is naturally low (such as seasonally dry forest regions) and promote forest regeneration and restoration in humid tropical lowland areas with high biomass resilience.,Above-ground biomass of Neotropical secondary forests databaseThis database is the product of the 2ndFOR collaborative research network on secondary forests. The database contains aboveground biomass data (in Mg/ha) for 1334 secondary forest plots differing in time since abandonment. The plots belong to different chonosequence studies in the Neotropics. For a description of the database, see Poorter et al. 2016. Biomass resilience of Neotropical secondary forests. Nature doi:10.1038/nature16512.Aboveground biomass 2ndFOR database.cs

Data from: Biomass resilience of Neotropical secondary forests

Land-use change occurs nowhere more rapidly than in the tropics, where the imbalance between deforestation and forest regrowth has large consequences for the global carbon cycle1. However, considerable uncertainty remains about the rate of biomass recovery in secondary forests, and how these rates are influenced by climate, landscape, and prior land use2, 3, 4. Here we analyse aboveground biomass recovery during secondary succession in 45 forest sites and about 1,500 forest plots covering the major environmental gradients in the Neotropics. The studied secondary forests are highly productive and resilient. Aboveground biomass recovery after 20 years was on average 122 megagrams per hectare (Mg ha−1), corresponding to a net carbon uptake of 3.05 Mg C ha−1 yr−1, 11 times the uptake rate of old-growth forests. Aboveground biomass stocks took a median time of 66 years to recover to 90% of old-growth values. Aboveground biomass recovery after 20 years varied 11.3-fold (from 20 to 225 Mg ha−1) across sites, and this recovery increased with water availability (higher local rainfall and lower climatic water deficit). We present a biomass recovery map of Latin America, which illustrates geographical and climatic variation in carbon sequestration potential during forest regrowth. The map will support policies to minimize forest loss in areas where biomass resilience is naturally low (such as seasonally dry forest regions) and promote forest regeneration and restoration in humid tropical lowland areas with high biomass resilience