Hostname: page-component-78c5997874-4rdpn Total loading time: 0 Render date: 2024-11-19T16:40:23.082Z Has data issue: false hasContentIssue false
  • English
  • Français

Herb–subshrub diversity in open savanna sites with distinct fire regimes in the Jalapão region, Brazil

Published online by Cambridge University Press:  23 May 2022

Guilherme Medeiros Antar Open the ORCID record for Guilherme Medeiros Antar [Opens in a new window] ,
Vânia Regina Pivello ,
Caian Souza Gerolamo ,
Anselmo Nogueira  and
Paulo Takeo Sano
Guilherme Medeiros Antar*
Affiliation:
Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, Rua do Matão 277, São Paulo, SP, 05508-090, Brazil Instituto Tecnológico Vale, Rua Boaventura da Silva 955, Belém, PA66055-090, Brazil
Vânia Regina Pivello
Affiliation:
Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, Travessa 14, São Paulo, SP05508-090, Brazil
Caian Souza Gerolamo
Affiliation:
Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, Rua do Matão 277, São Paulo, SP, 05508-090, Brazil
Anselmo Nogueira
Affiliation:
Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Alameda da Universidade, São Bernardo do Campo, SP, 09606-045, Brazil
Paulo Takeo Sano
Affiliation:
Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, Rua do Matão 277, São Paulo, SP, 05508-090, Brazil
*
Author for correspondence: Guilherme Medeiros Antar, Email: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

The fire regime is essential in creating a mosaic of plant structure and diversity in South American open savannas, especially favouring herbs. However, studies investigating diversity patterns in Neotropical savannas rarely focus on the herb–subshrub layer. This study investigated the variation of the herb–subshrub layer under contrasting fire regimes in the most conserved site within the Cerrado Domain, the Jalapão region, Brazil. We selected four sites of open savanna physiognomy with similar topographic, climatic and edaphic features: three burned every 2 years, while the fourth site has remained unburned for at least the last 10 years. We randomly distributed 15 plots of 4 m2 in each site and identified all herbs and subshrubs in each plot to estimate density, richness, alpha diversity and species composition. The unburned site had lower herb–subshrub density, richness and diversity than the frequently burned sites. Species composition varied between frequently burned and unburned sites, partially explained by the fire frequency across sites. Although other ecological factors may explain the patterns detected, we cannot rule out the importance of fire in structuring plant communities in the Jalapão region. As in other savannas, our study in the Cerrado Domain reinforces the essential role of the fire regimes in modifying and maintaining the diversity of herbaceous plants at the landscape scale.

Keywords

campo sujofire managementNeotropical savannaplant distributionvegetation structure
Type
Research Article
Information
Journal of Tropical Ecology , Volume 38 , Issue 6 , November 2022 , pp. 331 - 339
Check for updates
Copyright
© The Author(s), 2022. Published by Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Abreu, RCR, Hoffmann, WA, Vasconcelos, HL, Pilon, NA, Rossatto, DR and Durigan, G (2017) The biodiversity cost of carbon sequestration in tropical savanna. Science Advances 3, e1701284.CrossRefGoogle ScholarPubMed
Alvares, CA, Stape, JL, Sentelhas, PC, Gonçalves, JLM and Sparovek, G (2014) Köppen’s climate classification map for Brazil. Meterologische Zeitschrift 22, 711–728.CrossRefGoogle Scholar
Amaral, AG, Munhoz, CBR, Eugênio, CUO, Felfili, JM (2013) Vascular flora in dry-shrub and wet grassland Cerrado seven years after a fire, Federal District, Brazil. Check List 9, 387–503.CrossRefGoogle Scholar
Amaral, AG, Munhoz, CBR, Walter, BMT, Aguirre-Gutierrez, J and Raes, N (2017) Richness pattern and phytogeography of the Cerrado herb–shrub flora and implications for conservation. Journal of Vegetation Science 28, 848–858.CrossRefGoogle Scholar
Antar, GM and Sano, PT (2019) Angiosperms of dry grasslands and savannas of Jalapão, the largest conserved Cerrado area in Brazil. Rodriguésia 70, e04002017.CrossRefGoogle Scholar
Antar, GM, Santos, MF and Sano, PT (2017) Rediscovery and taxonomic reassessment of four angiosperms in the savannas of Jalapão, Central Brazil. Edinburgh Journal of Botany 75, 55–71.CrossRefGoogle Scholar
APG IV (2016) An update of the Angiosperm Phylogeny group classification for the orders and families of flowering plants: APG IV. Botanical Journal of Linnean Society 181, 1–20.CrossRefGoogle Scholar
Araújo, D, Antar, GM and Lombardi, JA (2016). Dioscorea compacta (Dioscoreaceae), a new endangered dwarf species from the Jalapão region, Tocantins, Brazil. Kew Bulletin 71, 27–32.CrossRefGoogle Scholar
Barbosa-Silva, R and Antar, GM (2020) Description vs deforestation: Couepia brevistaminea (Chrysobalanaceae) a new species on the frontier of deforestation in the Brazilian savanna. Phytotaxa 471, 38–46.CrossRefGoogle Scholar
Batmanian, GJ and Haridasan, M (1985) Primary production and accumulation of nutrients by the ground layer community of cerrado vegetation of central Brazil. Plant and Soil 88, 437–440.CrossRefGoogle Scholar
Beentje, H (2012) The Kew Plant Glossary: An Illustrated Dictionary of Plant Terms. United Kingdom: Royal Botanical Garden, Kew, 164 pp.Google Scholar
Berlinck, CN and Batista, EKL (2020) Good fire, bad fire: it depends on who burns. Flora 268, 151610.CrossRefGoogle Scholar
Berlinck, CN and Lima, LHA (2021) Implementation of integrated fire management in Brazilian federal protected areas: results and perspectives. Biodiversidade Brasileira 11, 1–11.Google Scholar
BFG - The Brazil Flora Group (2015) Growing knowledge: an overview of Seed Plant diversity in Brazil. Rodriguésia 66, 1085–1113.CrossRefGoogle Scholar
Bond, WJ and Keeley, JE (2005) Fire as a global ‘herbivore’: the ecology and evolution of flammable ecosystems. Trends in Ecology and Evolution 20, 387–394.CrossRefGoogle ScholarPubMed
Borges, LM and Antar, GM (2016). Four they are! Broadening the description of Mimosa flabelifolia (Leguminosae Mimosoideae), a rare species from the Brazilian Cerrado. Phytotaxa, 243, 155–162.CrossRefGoogle Scholar
Borges, SL, Eloy, L, Schmidt, IB, Barradas, ACS and Santos, IAD (2016) Fire Management in veredas (palm swamps): new perspectives on traditional farming systems in Jalapão, Brazil. Ambiente & Sociedade 19, 269–294.CrossRefGoogle Scholar
Câmara, PE and Leite, RN (2005) Bryophytes from Jalapão, state of Tocantins, northern Brazil. Tropical Bryology 26, 23–29.Google Scholar
Camargo, OA, Moniz, AC, Jorge, JA and Valadares, JMAS (1986). Métodos de análise química e física de solos do Instituto Agronômico do Estado de São Paulo. Boletim Técnico 106, 1–94.Google Scholar
Canales, J, Trevisan, MC, Silva, JF and Caswell, H (1994) A demographic study of an annual grass (Andropogon brevifolius Schwrz) in burnt and unburnt savanna. Acta Oecologica 15, 261–273.Google Scholar
César, HL (1980) Efeitos da queima e corte sobre a vegetação de campo sujo na Fazenda Água Limpa, Brasília-DF. Brasília. Master Thesis. Universidade de Brasília – Ecology Department.Google Scholar
Chiarello, AG, Aguiar, LMS, Cerqueira, R, Melo, FR, Rodrigues, FHG and Silva, VMF (2008) Mamíferos Ameaçados de Extinção no Brasil. In Machado, ABM, Drummond, GM and Paglia, AP (eds.), Livro Vermelho da Fauna Brasileira Ameaçada de Extinção. 1st ed. Rio de Janeiro: Fundação Biodiversitas, pp. 681–874.Google Scholar
Coutinho, LM (1976) Contribuição ao conhecimento do papel ecológico das queimadas na floração de espécies do cerrado. Tese de livre docência, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil.Google Scholar
Coutinho, LM (1982) Ecological effects of fire in Brazilian Cerrado. In Huntley, BJ and Walker, BH (eds.), Ecology of tropical savannas. Germany: Springer Verlag, pp. 273–291.CrossRefGoogle Scholar
Coutinho, LM (1990) Fire in the ecology of Brazilian Cerrado. Ecological Studies: Analysis and Synthesis 84, 82–105.CrossRefGoogle Scholar
Devecchi, MF and Pirani, JR (2015) A new species of Simaba sect. Grandiflorae (Simaroubaceae) from Jalapão region, Tocantins, Brazil. Phytotaxa 227, 167–174.CrossRefGoogle Scholar
Dias, BFS and Miranda, HS (2010) O projeto fogo. In Miranda, HS (ed.), Efeitos do regime do fogo sobre a comunidade de cerrado: Resultados do Projeto Fogo. Brasília: Ibama-MMA, pp. 15–22.Google Scholar
Durigan, G, Pilon, N, Assis, GB and Souza, FM (2018) Plantas pequenas do cerrado: biodiversidade negligenciada/. São Paulo: Secretaria do Meio Ambiente do Estado de São Paulo.Google Scholar
Durigan, G and Ratter, JA (2016) The need for a consistent fire policy for Cerrado conservation. Journal of Applied Ecology 53, 11–15.CrossRefGoogle Scholar
Eiten, G (1972) The cerrado vegetation of Brazil. Botanical Review 38, 201–341.CrossRefGoogle Scholar
Eloy, L, Schmidt, IB, Borges, SL, Ferreira, MC and Santos, TA (2018). Seasonal fire management by traditional cattle ranchers prevents the spread of wildfire in the Brazilian Cerrado. Ambio 48, 890–899.CrossRefGoogle ScholarPubMed
Fidelis, A, Alvarado, ST, Barradas, ACS and Pivello, VR (2018). The year 2017: megafires and management in the Cerrado. Fire 1, 49.CrossRefGoogle Scholar
Fidelis, A and Zirondi, HL (2021) And after fire, the Cerrado flowers: a review of post-fire flowering in a tropical savanna. Flora 280, 151849.CrossRefGoogle Scholar
Fisher, RA, Corbet, AS and Williams, CB (1943) The relation between the number of species and the number of individuals in a random sample of an animal population. Journal of Animal Ecology 12, 42–58.CrossRefGoogle Scholar
Flora do Brasil 2020 (2020) Jardim Botânico do Rio de Janeiro. Available at: <http://floradobrasil.jbrj.gov.br/>. Accessed on: 01 October 2021..+Accessed+on:+01+October+2021.>Google Scholar
Forzza, RC, Baumgratz, JFA, Bicudo, CEM, Canhos, DAL, Carvalho, A, Coelho, MAN, Costa, AF, Costa, DP, Hopkins, MG, Leitman, PM, Lohmann, LG, Lughadha, EN, Maia, LC, Martinelli, G, Menezes, M, Morim, MP, Peixoto, AL, Pirani, JR, Prado, J, Queiroz, LP, Souza, S, Souza, VC, Stehmann, JR, Sylvestre, LS, Walter, BMT and Zappi, DC (2012) New Brazilian floristic list highlights conservation challenges. Bioscience 62, 39–45.CrossRefGoogle Scholar
Gonçalves, RVS, Cardoso, JCF, Oliveira, PE and Oliveira, DC (2021) Changes in the Cerrado vegetation structure: insights from more than three decades of ecological succession. Web Ecology 21, 55–64.CrossRefGoogle Scholar
Gottsberger, G and Silberbauer-Gottsberger, I (2006) Life in the Cerrado, a South American Tropical Seasonal Ecosystem. Volume 1. Origin, Structure, Dynamics and Plant Use. Germany: Reta Verlag, 277 p.Google Scholar
Henriques, RPB (2005). Influência da história, solo e fogo na distribuição e dinâmica das fitofisionomias no bioma do Cerrado. In Souza-Silva, JC and Felfili, JM (eds), Cerrado: Ecologia, Biodiversidade e Conservação. Brasília: Ministério do Meio Ambiente, Brasília, pp. 73–92.Google Scholar
Hoffmann, WA (1999). Fire and population dynamics of woody plants in a neotropical savanna: matrix model projections. Ecology 80, 1354–1369.CrossRefGoogle Scholar
Legendre, P and Legendre, L (1998) Numerical ecology. 2nd English Edition, Amsterdam: Elsevier.Google Scholar
Loiola, PP, Cianciaruso, MV, Silva, IA and Batalha, MA (2010) Functional diversity of herbaceous species under different fire frequencies in Brazilian savannas. Flora 205, 674–681.CrossRefGoogle Scholar
Mace, GM (2004) The role of taxonomy in species conservation. Philosophical Transactions of the Royal Society of London B 359, 711–719.CrossRefGoogle ScholarPubMed
Mariano, V, Rebolo, IF and Christianini, AV (2019). Fire-sensitive species dominate seed rain after fire suppression: implications for plant community diversity and woody encroachment in the Cerrado. Biotropica 51, 5–9.CrossRefGoogle Scholar
McCune, B and Grace, JB (2002) Analysis of ecological communities. Gleneden Beach, Oregon: MjM Software Design.Google Scholar
Miranda, HS (2010) Efeitos do regime de fogo sobre a estrutura de comunidades de Cerrado: Projeto Fogo. Brasília: IBAMA.Google Scholar
Miranda, HS, Bustamante, MMC and Miranda, AC (2002) The fire factor. In Oliveira, PS and Marquis, RJ (eds), The Cerrados of Brazil: ecology and natural history of a neotropical savanna. New York: Columbia University Press, pp. 51–68.Google Scholar
Miranda, HS, Neto, WN and Neves, BMC (2010) Caracterização das queimadas de Cerrado. In Miranda, HS (ed.). Efeitos do regime do fogo sobre a comunidade de cerrado: Resultados do Projeto Fogo. Brasília: Ibama-MMA, pp. 23–33.Google Scholar
Miranda, MI (2002) Efeito de diferentes regimes de queima sobre a comunidade de gramíneas de Cerrado. Master Thesis. Universidade Nacional de Brasília, Bazil.Google Scholar
Montenegro, SR (2019). Efeitos do manejo do fogo na estrutura de comunidades lenhosas em formações savânicas do Cerrado. Master Thesis. Instituto de Ciências Biológicas, Departamento de Ecologia, Universidade de Brasília, Brazil.Google Scholar
Moreira, AG (2000). Effects of fire protection on savanna structure in Central Brazil. Journal of Biogeography 27, 1021–1029.CrossRefGoogle Scholar
Moreira, ALC, Antar, GM, Simão-Bianchini, R and Cavalcanti, TB (2017). Contribution to the knowledge of Bonamia (Convolvulaceae) in Brazil: a new species and a new occurrence. Phytotaxa 306, 146–152.CrossRefGoogle Scholar
Munhoz, CBR (2003) Padrões de distribuição sazonal e espacial das espécies do estrato herbáceo-subarbustivo em comunidades de campo limpo úmido e de campo sujo. Ph.D. Thesis. Instituto de Ciências Biológicas, Departamento de Ecologia, Universidade de Brasília, Brazil.Google Scholar
Oksanen, JF, Blanchet, G, Kindt, R, Legendre, P, Minchin, PR, O’Hara, RB, Simpson, GL, Solymos, P, Henry, M, Stevens, H and Wagner, H (2015) Vegam: Community Ecology Package. R package version – 2.2.-1. http://CRAN.Rproject.org/package=vegan Google Scholar
Palmer, MW (1991) Estimating species richness: the second-order Jackknife reconsidered. Ecology 72: 1512–1513. doi: 10.2307/1941127.CrossRefGoogle Scholar
Pastore, JFB and Antar, GM (2021). Two new endangered species of Polygala series Trichospermae (Polygalaceae), endemic to the Cerrado Domain, Tocantins State, Brazil. European Journal of Taxonomy 762, 133–148.CrossRefGoogle Scholar
Pereira-Júnior, AC, Oliveira, SLJ, Pereira, JMC, Turkman, MAA (2014) Modelling fire frequency in a Cerrado Savanna protected area. Plos One 9, e102380.CrossRefGoogle Scholar
Pilon, NA, Cava, MGB, Hoffmann, WA, Abreu, RCR, Fidelis, A and Durigan, G (2020) The diversity of post-fire regeneration strategies in the cerrado ground layer. Journal of Ecology 109, 154–166.CrossRefGoogle Scholar
Pivello, VR (2011). The use of fire in the Cerrado and Amazonian rainforests of Brazil: past and present. Fire Ecology 7, 24–39.CrossRefGoogle Scholar
Pivello, VR and Coutinho, LM (1992). Transfer of macro-nutrients to the atmosphere during experimental burnings in an open cerrado (Brazilian savanna). Journal of Tropical Ecology 8, 487–497.CrossRefGoogle Scholar
Pivello, VR and Coutinho, LM (1996) A qualitative successional model to assist in the management of Brazilian cerrados. Forest Ecology Management 87, 127–138.CrossRefGoogle Scholar
Pivello, VR and Norton, GA (1996) Firetool: an expert system for the use of prescribed fires in Brazilian savannas. Journal of Applied Ecology 33, 348–356.CrossRefGoogle Scholar
Pivello, VR, Vieira, I, Christianini, AV, Ribeiro, DB, da Silva Menezes, L, Berlinck, CN, Melo, FP, Marengo, JA, Tornquist, CG, Tomas, WM and Overbeck, GE (2021). Understanding Brazil’s catastrophic fires: causes, consequences and policy needed to prevent future tragedies. Perspectives in Ecology and Conservation 19, 233–255.CrossRefGoogle Scholar
Proença, CEB, Farias-Singer, R and Gomes, BM (2007) Pleonotoma orientalis (Bignoniaceae-Bignonieae): expanded description, distribution and a new variety of a poorly known species. Edinburgh Journal of Botany 64, 17–23.CrossRefGoogle Scholar
Raij, BV, Quaggio, JA, Cantarella, H, Ferreira, ME, Lopes, AS and Bataglia, OC (1987). Análise química de solos para fins de fertilidade. Campinas: Fundação Cargill.Google Scholar
Ramos-Neto, MB and Pivello, VR (2000) Lightning fires in a Brazilian Savanna national park: rethinking management strategies. Environmental Management 26, 675–684.CrossRefGoogle Scholar
Ratter, JA, Ribeiro, JF and Bridgewater, S (1997) The Brazilian Cerrado vegetation and threats to its biodiversity. Annals of Biology 80, 223–230.Google Scholar
R CORE TEAM (2020) R: A language and environment for statistical computing. Vienna, Austria: R Foundation for Statistical Computing, URL http://www.R-project.org/.Google Scholar
Ribeiro, JF and Walter, BMT (2008) As principais fitofisionomias do bioma Cerrado. In Sano, SM, Almeida, SP and Ribeiro, JF (eds.), Cerrado: Ecologia e flora. EMBRAPA. Vol. 1, pp. 153–212.Google Scholar
Rodrigues, CA, Zirondi, HL and Fidelis, A (2021) Fire frequency affects fire behavior in open savannas of the Cerrado. Forest Ecology and Management 482, 118850.CrossRefGoogle Scholar
Santos, AC (2019). Efeitos de diferentes regimes de queima sobre o estrato herbáceo-subarbustivo da vegetação em áreas de Manejo Integrado do Fogo no Cerrado. Master Thesis. Instituto de Ciências Biológicas, Departamento de Ecologia, Universidade de Brasília, Brazil.Google Scholar
Santos, FLM, Nogueira, J, Souza, RAF, Falleiro, RM, Scmidt, IB and Libonati, R (2021) Prescribed burning reduces large, high-intensity wildfires and emissions in the Brazilian Savanna. Fire 4, 1–21.CrossRefGoogle Scholar
Santos, RP, Crema, A, Szmuchrowski, MA, Asano, K and Kawaguchi, M (2011). Atlas do corredor ecológico da região do Jalapão. Instituto Chico Mendes de Conservação da Biodiversidade.Google Scholar
Sarmiento, G (1984) The ecology of neotropical savannas. Cambridge: Harvard University.CrossRefGoogle Scholar
Sato, MN, Miranda, HS and Maia, JMF (2010) O fogo e o estrato arbóreo do Cerrado: efeitos imediatos e de longo prazo. In Miranda, HS, Efeitos do regime do fogo sobre a comunidade de cerrado: Resultados do Projeto Fogo. Brasília: Ibama–MMA, pp. 77–91.Google Scholar
Schmidt, IB, Fidelis, A, Miranda, HS and Ticktin, T (2017) How do the wets burn? Fire behavior and intensity in wet grasslands in the Brazilian savanna. Revista Brasileira de Botanica 40, 167–175.Google Scholar
Schmidt, IB, Figueiredo, IB and Scariot, A (2007) Ethnobotany and effects of harvesting on the population of Syngonanthus nitens (Bong.) Ruhland (Eriocaulaceae), a NTFP from Jalapão region, Central Brazil. Economic Botany 61, 73–85.CrossRefGoogle Scholar
Schmidt, IB, Moura, LC, Ferreira, MC, Eloy, L, Sampaio, AB, Dias, PA and Berlinck, CN (2018) Fire management in the Brazilian savanna: first steps and the way forward. Journal of Applied Ecology 55, 2094–2101.CrossRefGoogle Scholar
SEPLAN – Secretaria do Planejamento e Meio Ambiente do Estado do Tocantins (2003a) Plano de Manejo do Parque Estadual do Jalapão. Palmas: Seplan.Google Scholar
SEPLAN – Secretaria do Planejamento e Meio Ambiente do Estado de Tocantins (2003b) Plano de Manejo da Área de Proteção Ambiental do Jalapão. Palmas: Seplan.Google Scholar
SEPLAN – Secretaria do Planejamento e Meio Ambiente do Estado de Tocantins (2012) Atlas do Tocantins: Subsídios ao Planejamento da Gestão Territorial. Palmas: Seplan.Google Scholar
Silva, DM and Batalha, MA (2011) Defense syndromes against herbivory in a cerrado plant community. Plant Ecology 212, 181–193.CrossRefGoogle Scholar
Silva, DP, Amaral, AG, Bijos, NR and Munhos, CBR (2018) Is the herb-shrub composition of veredas (Brazilian palm swamps) distinguishable? Acta Botanica Brasilica 32, 47–54.CrossRefGoogle Scholar
Silva, JMC and Bates, JM (2002) Biogeographic patterns and conservation in the South America Cerrado: a tropical Savana Hotspot. BioScience 52, 225–233.CrossRefGoogle Scholar
Simon, MF, Grether, R, Queiroz, LP, Skema, C, Pennington, RT and Hughes, CE (2009) Recent assembly of the cerrado, a neotropical plant diversity hotspot, by in situ evolution of adaptations to fire. Proceedings of the National Academy of Science 10, 20359–20364.CrossRefGoogle Scholar
Stevens, N, Lehmann, C, Murphy, BP and Durigan, G (2017) Savanna woody encroachment is widespread across three continents. Global Change Biology 23, 235–244.CrossRefGoogle ScholarPubMed
Strassburg, BBN, Brooks, T, Feltran-Barbieri, R, Iribarrem, A, Crouzeilles, R, Loyola, R, Latawiec, AE, Oliveira Filho, FJB., Scaramuzza, CAM, Scarano, FR, Soares-Filho, B and Balmford, A (2017) Moment of truth for the Cerrado hotspot. Nature Ecology & Evolution 1, 0099.CrossRefGoogle ScholarPubMed
Zuquim, G, Costa, FR, Prado, J and Braga-Neto, R (2009) Distribution of pteridophyte communities along environmental gradients in Central Amazonia, Brazil. Biodiversity and Conservation 18, 151–166.CrossRefGoogle Scholar
Supplementary material: File

Antar et al. supplementary material

Antar et al. supplementary material 1

Download Antar et al. supplementary material(File)
File 19.5 KB
Supplementary material: File

Antar et al. supplementary material

Antar et al. supplementary material 2

Download Antar et al. supplementary material(File)
File 272.2 KB
Supplementary material: File

Antar et al. supplementary material

Antar et al. supplementary material 3

Download Antar et al. supplementary material(File)
File 13.6 KB