1. Structural, physiognomic and above-ground biomass variation in savanna-forest transition zones on three continents - How different are co-occurring savanna and forest formations?
- Author
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Keith J. Bloomfield, J. Gignoux, Jon Lloyd, Michael I. Bird, Kofi Affum-Baffoe, Daniel Villarroel, Kalu Davies, Halidou Compaore, Michael P. Schwarz, Tomas F. Domingues, Heloisa Sinatora Miranda, J Kemp, Ben Hur Marimon-Junior, Andrew Ford, Gloria Djagbletey, J. A. Ratter, Ted R. Feldpausch, Gustavo Saiz, G. Ceca, Louis Zapfack, Daniel J. Metcalfe, F. Yoko Ishida, Eric Mougin, Fidele Hien, F. Gerard, Mireia Torello-Raventos, Michelle L. Johnson, Beatriz Schwantes Marimon, Karle Sykora, Gabriela Bielefeld Nardoto, Martin Gilpin, Pierre Hiernaux, Bonaventure Sonké, Carlos A. Quesada, Timothy J. Killeen, John Grace, Nikolaos M. Fyllas, Oliver L. Phillips, Adama Diallo, Denise Sasaki, Elmar Veenendaal, Franziska Schrodt, Simon L. Lewis, Leandro Maracahipes, L. Arroyo, Marc K. Steininger, Eddie Lenza, Unité de recherche Biogéochimie des Ecosystèmes Forestiers (BEF), Institut National de la Recherche Agronomique (INRA), Chercheur indépendant, Laboratoire de Botanique systématique et d'Ecologie [ENS Yaoudé], Université de Yaoundé I-École normale supérieure [ENS] - Yaoundé 1, School of Geography, Earth and Biosphere Institute, University of Leeds, Museo Noel Kempff Mercado, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM)-IFR48, Institut des sciences biologiques (INSB-CNRS)-Institut des sciences biologiques (INSB-CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Ecologie et évolution, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Centre d'études spatiales de la biosphère (CESBIO), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Center for Applied Biodiversity Science, Conservation Int., Physics and Materials Science Research Unit, University of Luxembourg, University of Luxembourg [Luxembourg], Institute of Ecology and Resource Management, University of Edinburgh, Earth and Biosphere Institute, School of Geography, The Royal Society, Université de Yaoundé I [Yaoundé]-École normale supérieure [ENS] - Yaoundé 1, University of Greenwich, INSB-INSB-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-École normale supérieure - Paris (ENS Paris), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Canopy ,0106 biological sciences ,national-park ,010504 meteorology & atmospheric sciences ,05 Environmental Sciences ,lcsh:Life ,alternative stable states ,01 natural sciences ,Aboveground Biomass ,Remote Sensing ,Savanna ,ddc:550 ,Meteorology & Atmospheric Sciences ,Vegetation Type ,Geosciences, Multidisciplinary ,ComputingMilieux_MISCELLANEOUS ,Biomass (ecology) ,Understory ,Ecology ,Leaf Area Index ,Grass ,lcsh:QE1-996.5 ,Geology ,Vegetation ,PE&RC ,Transition Zone ,southern africa ,Physical Sciences ,amazonian forest ,Plantenecologie en Natuurbeheer ,Life Sciences & Biomedicine ,Forest transition ,Woody plant ,tropical forest ,[INFO.INFO-CC]Computer Science [cs]/Computational Complexity [cs.CC] ,04 Earth Sciences ,Environmental Sciences & Ecology ,Plant Ecology and Nature Conservation ,ECOFISIOLOGIA VEGETAL ,Poaceae ,functional types ,010603 evolutionary biology ,Ecology and Environment ,[SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems ,Climate Effect ,Alternative stable state ,lcsh:QH540-549.5 ,brazilian cerrado ,Bosecologie en Bosbeheer ,[SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment ,cerrado vegetation ,Ecology, Evolution, Behavior and Systematics ,Earth-Surface Processes ,0105 earth and related environmental sciences ,Woody Plant ,Tree canopy ,Herb ,Science & Technology ,tree height ,Australia ,South America ,06 Biological Sciences ,15. Life on land ,[INFO.INFO-MO]Computer Science [cs]/Modeling and Simulation ,Floristics ,Forest Ecology and Forest Management ,lcsh:Geology ,Earth sciences ,lcsh:QH501-531 ,13. Climate action ,Forest Canopy ,Africa ,lcsh:Ecology ,[SDE.BE]Environmental Sciences/Biodiversity and Ecology ,Coexistence ,woody vegetation - Abstract
Through interpretations of remote-sensing data and/or theoretical propositions, the idea that forest and savanna represent "alternative stable states" is gaining increasing acceptance. Filling an observational gap, we present detailed stratified floristic and structural analyses for forest and savanna stands located mostly within zones of transition (where both vegetation types occur in close proximity) in Africa, South America and Australia. Woody plant leaf area index variation was related to tree canopy cover in a similar way for both savanna and forest with substantial overlap between the two vegetation types. As total woody plant canopy cover increased, so did the relative contribution of middle and lower strata of woody vegetation. Herbaceous layer cover declined as woody cover increased. This pattern of understorey grasses and herbs progressively replaced by shrubs as the canopy closes over was found for both savanna and forests and on all continents. Thus, once subordinate woody canopy layers are taken into account, a less marked transition in woody plant cover across the savanna–forest-species discontinuum is observed compared to that inferred when trees of a basal diameter > 0.1 m are considered in isolation. This is especially the case for shrub-dominated savannas and in taller savannas approaching canopy closure. An increased contribution of forest species to the total subordinate cover is also observed as savanna stand canopy closure occurs. Despite similarities in canopy-cover characteristics, woody vegetation in Africa and Australia attained greater heights and stored a greater amount of above-ground biomass than in South America. Up to three times as much above-ground biomass is stored in forests compared to savannas under equivalent climatic conditions. Savanna–forest transition zones were also found to typically occur at higher precipitation regimes for South America than for Africa. Nevertheless, consistent across all three continents coexistence was found to be confined to a well-defined edaphic–climate envelope with soil and climate the key determinants of the relative location of forest and savanna stands. Moreover, when considered in conjunction with the appropriate water availability metrics, it emerges that soil exchangeable cations exert considerable control on woody canopy-cover extent as measured in our pan-continental (forest + savanna) data set. Taken together these observations do not lend support to the notion of alternate stable states mediated through fire feedbacks as the prime force shaping the distribution of the two dominant vegetation types of the tropical lands.
- Published
- 2015