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[Aim]: Fire is a natural disturbance in many ecosystems throughout the world where plant populations can persist by the resprouting of individuals and/or by recruiting from seeds. We evaluated the post-fire regeneration response for 41 coexisting species, including grasses, forbs, and shrubs, from an open Cerrado community (campo sujo) in Central Brazil., [Location]: The study was conducted at the Reserva Natural Serra do Tombador (RNST) in Central Brazil. The vegetation of the study area is characterized by a continuous herbaceous layer dominated by grasses and scattered shrubs, which produces fine fuel loads that can burn frequently., [Methods]: We examined both resprouting ability after experimental fires, accounting for bud location, and seed response to heat shocks caused by fire, where seeds were subjected to heat shocks of 100°C for one and three minutes, 200°C for one minute, and a control (untreated seeds)., [Results]: All species were able to resprout (R+) after fire, mainly from buds located in underground structures, but also from aerial and basal buds. Seeds of most species tolerated heat shocks of 100°C for one and three minutes, but heat treatments of 200°C decreased seed viability of nearly 50% of species. Seven species, all of which had dormant seeds, showed heat-stimulated germination. In sum, 81% of the community was classified as R+PT (resprouters with heat-tolerant propagules) and 17% was R+PS (resprouters with heat-stimulated propagules). The remaining 2% (one species) was classified as R+P−, showing heat-sensitive seeds., [Conclusions]: Resprouting is the main post-fire regeneration strategy in Cerrado open savannas, while fire-stimulated germination, although possible, is less common in comparison to the frequency in other fire-prone ecosystems. However, in Cerrado open savannas, heat tolerance is an important trait that enables germination when favorable conditions arise., This study was funded by FAPESP, the São Paulo Research Foundation (2015/06743-0), the National Council for Scientific and Technological Development - CNPq (455183/2014-7) and Fundação Grupo Boticário (0153_2011_PR). A. Fidelis receives a productivity grant from CNPq (303988/2018-5).

Information from a field perspective on temperature thresholds related to physical dormancy (PY) alleviation and seed resistance to high temperatures of fire is crucial to disentangle fire- and non-fire-related germination cues. We investigated seed germination and survival of four leguminous species from a frequently burned open Neotropical savanna in Central Brazil. Three field experiments were conducted according to seed location in/on the soil: (1) fire effects on exposed seeds; (2) fire effects on buried seeds; and (3) effects of temperature fluctuations on exposed seeds in gaps and shaded microsites in vegetation. After field treatments, seeds were tested for germination in the laboratory, together with the control (non-treated seeds). Fire effects on exposed seeds decreased viability in all species. However, germination of buried Mimosa leiocephala seeds was enhanced by fire in an increased fuel load treatment, in which we doubled the amount of above-ground biomass. Germination of two species (M. leiocephala and Harpalyce brasiliana) was enhanced with temperature fluctuation in gaps, but this condition also decreased seed viability. Our main conclusions are: (1) most seeds died when exposed directly to fire; (2) PY could be alleviated during hotter fires when seeds were buried in the soil; and (3) daily temperature fluctuations in gaps also broke PY of seeds on the soil surface, so many seeds could be recruited or die before being incorporated into the soil seed banks. Thus seed dormancy-break and germination of legumes from Cerrado open savannas seem to be driven by both fire and temperature fluctuations.

The search for predictions of species diversity across environmental gradients haschallenged ecologists for decades. The humped-back model (HBM) suggests that plantdiversity peaks at intermediate productivity; at low productivity few species can toleratethe environmental stresses, and at high productivity a few highly competitive speciesdominate. Over time the HBM has become increasingly controversial, and recent studiesclaim to have refuted it. Here, by using data from coordinated surveys conductedthroughout grasslands worldwide and comprising a wide range of site productivities, weprovide evidence in support of the HBM pattern at both global and regional extents. Therelationships described here provide a foundation for further research into the local,landscape, and historical factors that maintain biodiversity. Fil: Fraser, Lauchlan H.. Thompson Rivers University; Estados Unidos Fil: Pither, Jason. University of British Columbia; Canadá Fil: Jentsch, Anke. University Of Bayreuth; Alemania Fil: Sternberg, Marcelo. Tel Aviv University; Israel Fil: Zobel, Martín. University Of Tartu.; Estonia Fil: Cabido, Marcelo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Díaz, Sandra Myrna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Enrico, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Nabinger, Carlos. Universidade Federal do Rio Grande do Sul; Brasil Fil: Naseri, Kamal. Ferdowsi University of Mashhad; Irán Fil: Overbeck, Gerhard E.. Universidade Federal do Rio Grande do Sul; Brasil Fil: Palmer, Todd M.. University of Florida; Estados Unidos Fil: Parsons, Sheena. University of Kansas; Estados Unidos Fil: Pesek, Mary. University of Kansas; Estados Unidos Fil: Pillar, Valério D.. Universidade Federal do Rio Grande do Sul; Brasil Fil: Pringle, Robert M.. Princeton University; Estados Unidos Fil: Roccaforte, Kathy. University of Kansas; Estados Unidos Fil: Schmidt, Amanda. Thompson Rivers University; Canadá Fil: Shang, Zhanhuan. Lanzhou University; China Fil: Stahlmann, Reinhold. University Of Bayreuth; Alemania Fil: Stotz, Gisela C.. University of Alberta; Canadá Fil: Sugiyama, Shu-ichi. Hirosaki University; Japón Fil: Szentes, Szilárd. Szent István University; Hungría Fil: Thompson, Don. Lethbridge Research Centre; Canadá Fil: Tungalag, Radnaakhand. National University of Mongolia; Mongolia Fil: Undrakhbold, Sainbileg. National University of Mongolia; Mongolia Fil: van Rooyen, Margaretha. University of Pretoria; Sudáfrica Fil: Wellstein, Camilla. Free University of Bozen Bolzano; Italia Fil: Wilson, J. Bastow. University Of Otago; Canadá. Crown Research Institutes. Landcare Research; Nueva Zelanda Fil: Zupo, Talita. Universidad Estadual Paulista; Brasil

Fire has played an important role in the plant dynamics and diversity of the Cerrado for millions of years. We evaluated fire behaviour in different fire seasons in areas of an open savanna, providing information for fire management plans. It has been hypothesised that early fires (May – end of the rainy season) will be less intense than those conducted in the middle and end of the dry season (July and October) owing to the amount of dead biomass accumulated. Therefore, we compared fire behaviour in early, mid- and late dry season, evaluating the main fire and environmental variables. Fire intensity was mainly influenced by the combination of dead fuel percentage and fuel load. Even though this combination was the best model to explain fire intensity variability, fire parameters (including fire intensity) did not differ between fire seasons. Flame height was best explained by dead fuel percentage + fuel moisture content, dead fuel percentage + fuel load and also by dead fuel percentage. Our study showed that, in areas with fire exclusion for 2 years, fire season did not influence fire parameters and fire behaviour and the main factors influencing fire intensity were the proportion of dead biomass and total fuel load. This study was supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, project (476334/2011–0) and scholarship (141854/2012-0), Fundação de Amparo à pesquisa do Estado de São Paulo (FAPESP, project 2015/06743–0), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES/DGU (grant 10805/13–3, project 227/2010), Neotropical Grassland Conservancy and Fundação Grupo o Boticário de Proteção à Natureza (0153_2011_PR). MJB acknowledges the support from the Foresterra ERA-Net (Medwildfirelab project PCIN-2013–140-C04–03) European Commission. AF receives a grant from CNPq (306170/2015–9).

Some invasive grasses have been reported to change fire behavior in invaded plant communities. Urochloa brizantha is an aggressive invasive grass in the Brazilian Cerrado, an ecosystem where fire is a common disturbance. We investigated the effects of U. brizantha on fire behavior in an open Cerrado physiognomy in Central Brazil. Using experimental burnings we compared fire behavior at both the community and the individual plant level in invaded (UJ) and non-invaded (NJ) areas burned in July. We also assessed the effect of fire season in invaded areas by comparing July (UJ) and October (UO) burnings. We evaluated the following variables: fuel load, fuel moisture, combustion efficiency, maximum fire temperature, flame height, and fire intensity. Additionally, we evaluated the temperatures reached under invasive and native grass tussocks in both seasons. Fuel load, combustion efficiency, and fire intensity were higher in NJ than in UJ, whilst flame height showed the opposite trend. Fuel amount and fire intensity were higher in October than in July. At the individual plant level, U. brizantha moisture was higher than that of native species, however, temperatures reaching ≥600 °C at ground level were more frequent under U. brizantha tussocks than under native grasses. At the community level, the invasive grass modified fire behavior towards lower intensity, lower burning efficiency, and higher flame height. These results provide essential information for the planning of prescribed burnings in invaded Cerrado areas. We thank the Fundação Grupo Boticário de Proteção à Natureza (Termo de Parceria No 0106_2011_PR), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES/DGU 227/2010), and the Ministry of Education (PHB2009-0073-PC) and of Science and Innovation (FEEDBACK Project; CGL2011-30515-C02-01) of the Spanish Goverment for financial support.

Made available in DSpace on 2018-11-26T17:06:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-07-01. Added 1 bitstream(s) on 2019-10-09T18:26:20Z : No. of bitstreams: 1 S0102-33062016000300514.pdf: 1393179 bytes, checksum: 3b61d8956ab09041e5bba7984470ccd7 (MD5) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) program FORESTERRA ERA-Net (Medwildfirelab) Seed germination in many species from fire-prone ecosystems may be triggered by heat shock and/or temperature fluctuation, and how species respond to such fire-related cues is important to understand post-fire regeneration strategies. Thus, we tested how heat shock and daily temperature fluctuations affect the germination of four species from fire-prone ecosystems; two from the Cerrado and two from the Mediterranean Basin. Seeds of all four species were subjected to four treatments: Fire (F), temperature fluctuations (TF), fire+temperature fluctuations (F+TF) and control (C). After treatments, seeds were put to germinate for 60 days at 25 degrees C (dark). Responses differed according to species and native ecosystem. Germination percentage for the Cerrado species did not increase with any of the treatments, while germination of one Mediterranean species increased with all treatments and the other only with treatments that included fire. Although the Cerrado species did not respond to the treatments used in this study, their seeds survived the exposure to heat shock, which suggests they possess tolerance to fire. Fire frequency in the Cerrado is higher than that in Mediterranean ecosystems, thus traits related to fire-resistance would be more advantageous than traits related to post-fire recruitment, which are widespread among Mediterranean species. Univ Estadual Paulista, Dept Bot, Inst Biociencias, Av 24A,1515, BR-13506900 Rio Claro, SP, Brazil Fdn Ctr Estudios Ambientales Mediterraneo, C Charles Darwin 14, Valencia 46980, Spain Univ Alicante, Dept Ecol, Ap 99, E-03080 Alicante, Spain Univ Estadual Paulista, Dept Bot, Inst Biociencias, Av 24A,1515, BR-13506900 Rio Claro, SP, Brazil CNPq: 455183/2014-7 CAPES: CAPES/DGU11623/13-6 FAPESP: FAPESP 2015/06743-0 program FORESTERRA ERA-Net (Medwildfirelab): PCIN-2013-140-C04-03 CNPq: 306170/2015-9

Tredennick et al. criticize one of our statistical analyses and emphasize the low explanatory power of models relating productivity to diversity. These criticisms do not detract from our key findings, including evidence consistent with the unimodal constraint relationship predicted by the humped-back model and evidence of scale sensitivities in the form and strength of the relationship. Fil: Pither, Jason. University of British Columbia; Canadá Fil: Fraser, Lauchlan H.. Thompson Rivers University; Canadá Fil: Jentsch, Anke. University of Bayreuth; Alemania Fil: Sternberg, Marcelo. Tel Aviv University; Israel Fil: Zobel, Martín. University of Tartu; Estonia Fil: Cahill, James. University of Alberta; Canadá Fil: Cabido, Marcelo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Díaz, Sandra Myrna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Enrico, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Carlyle, Cameron N.. University of Alberta; Canadá Fil: Chelli, Stefano. University of Camerino; Italia Fil: Cserg, Anna Maria. The University of Dublin; Irlanda Fil: Ensing, David. Queen’s University; Canadá Fil: Fidelis, Alessandra. Universidade Estadual Paulista; Brasil Fil: Garris, Heath W.. Thompson Rivers University; Canadá Fil: Henry, Hugh A. L.. University of Western Ontario; Canadá Fil: Höhn, Maria. Corvinus University of Budapest; Hungría Fil: Klironomos, John. University of British Columbia; Canadá Fil: Koorem, Kadri. University of Tartu; Estonia Fil: Lawrence Lodge, Rachel. University of Otago; Nueva Zelanda Fil: Manning, Peter. Senckenberg Gesellschaft für Naturforschung; Alemania Fil: Mitchell, Randall J.. University of Akron; Estados Unidos Fil: Moora, Mary. University of Tartu; Estonia Fil: Pillar, Valerio D.. Federal University of Rio Grande do Sul; Brasil Fil: Stotz, Gisela C.. University of Alberta; Canadá Fil: Sugiyama, Shu-ichi. Hirosaki University; Japón Fil: Szentes, Szilárd. Szent István University; Hungría Fil: Tungalag, Radnaakhand. National University of Mongolia; Mongolia Fil: Undrakhbold, Sainbileg. Free University of Bozen-Bolzano; Italia Fil: Wellstein, Camila. Free University of Bozen-Bolzano; Italia Fil: Zupo, Talita. Universidade Estadual Paulista; Brasil

The search for predictions of species diversity across environmental gradients has challenged ecologists for decades. The humped-back model (HBM) suggests that plant diversity peaks at intermediate productivity; at low productivity few species can tolerate the environmental stresses, and at high productivity a few highly competitive species dominate. Over time the HBM has become increasingly controversial, and recent studies claim to have refuted it. Here, by using data from coordinated surveys conducted throughout grasslands worldwide and comprising a wide range of site productivities, we provide evidence in support of the HBM pattern at both global and regional extents. The relationships described here provide a foundation for further research into the local, landscape, and historical factors that maintain biodiversity.