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Cette étude a consisté à caractériser les pâturages de l’enclave pastorale de Dadaria en termes de diversité floristique, valeur pastorale, productivité et capacité de charge. Un inventaire floristique de la végétation herbacée a été réalisé sur 53 placettes du sud au nord. Les résultats ont montré que le site comportait 93 espèces dont 83 herbacées réparties dans 30 familles et 63 genres. La flore était largement dominée par les Poaceae, et le type biologique le plus abondant et le plus dominant était celui des thérophytes. Le spectre fourrager a montré que la valeur pastorale a varié de 60 % dans le groupement 1 (G1) à 70 % dans G3. L’indice global de qualité des herbages a suivi la même tendance et a fluctué de 58 % dans G1 à 64 % dans G4. Cinq espèces (Spermacoce chaetocephala DC. Hepper., Alysicarpus ovalifolius Schum. & Thonn., Zornia glochidiata Reich. ex DC., Digitaria argillacea (Hitch. & Chase) Fern., et Chloris prieurii Kunth.) déterminaient 75 % des contributions spécifiques des espèces. La production de phytomasse herbacée globale a été estimée à 3,4 tonnes de matière sèche (MS) par hectare et a varié selon le groupement. L’analyse du spectre de la production fourragère par espèce herbacée a indiqué que S. chaetocephala (68 kg MS/ha), A. ovalifolius (20 kg MS/ha), C. prieurii (15 kg MS/ha) et Z. glochidiata (9 kg MS/ha) étaient les plus productives. S. chaetocephala a été la plus contributive et la plus productive mais avec une faible valeur pastorale. La disparition progressive des graminées annuelles (Cenchrus biflorus Roxb. et la tribu des Aristideae), qui présentent un très bon fourrage sec sur pied pour le bétail durant la saison sèche au profit des légumineuses fourragères qui disparaissent juste après la saison pluvieuse en laissant l’enclave nue, constitue une dynamique régressive du tapis herbacé de cet écosystème pastoral sahélien.

Major drivers of gains or losses in soil organic carbon (SOC) include land management, land-use change, and climate change. Thousands of original studies have focused on these drivers of SOC change and are now compiled in a growing number of meta-analyses. To critically assess the research efforts in this domain, we retrieved and characterized 192 meta-analyses of SOC stocks or concentrations. These meta-analyses comprise more than 13,200 original studies conducted from 1910 to 2020 in 150 countries. First, we show that, despite a growing number of studies over time, the geographical coverage of studies is limited. For example, the effect of land management, land-use change, and climate change on SOC has been only occasionally studied in North and Central Africa, and in the Middle East and Central Asia. Second, the meta-analyses investigated a limited number of land management practices, mostly mineral fertilization, organic amendments, and tillage. Third, the meta-analyses demonstrated relatively low quality and transparency. Lastly, we discuss the mismatch between the increasing number of studies and the need for more local, reusable, and diversified knowledge on how to preserve high SOC stocks or restore depleted SOC stocks.

Made available in DSpace on 2021-06-25T11:16:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Agence Nationale Des Parcs Nationaux Centre for International Forestry Research Departamento Administrativo de Ciencia, Tecnología e Innovación (COLCIENCIAS) David and Lucile Packard Foundation European Space Agency Leverhulme Trust Gordon and Betty Moore Foundation Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Fundação de Amparo à Pesquisa do Estado de Goiás European Research Council Belgian Federal Science Policy Office Vlaamse Interuniversitaire Raad Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) National Science Foundation Natural Environment Research Council Royal Society National Geographic Society Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Tropical forests are the most diverse and productive ecosystems on Earth. While better understanding of these forests is critical for our collective future, until quite recently efforts to measure and monitor them have been largely disconnected. Networking is essential to discover the answers to questions that transcend borders and the horizons of funding agencies. Here we show how a global community is responding to the challenges of tropical ecosystem research with diverse teams measuring forests tree-by-tree in thousands of long-term plots. We review the major scientific discoveries of this work and show how this process is changing tropical forest science. Our core approach involves linking long-term grassroots initiatives with standardized protocols and data management to generate robust scaled-up results. By connecting tropical researchers and elevating their status, our Social Research Network model recognises the key role of the data originator in scientific discovery. Conceived in 1999 with RAINFOR (South America), our permanent plot networks have been adapted to Africa (AfriTRON) and Southeast Asia (T-FORCES) and widely emulated worldwide. Now these multiple initiatives are integrated via ForestPlots.net cyber-infrastructure, linking colleagues from 54 countries across 24 plot networks. Collectively these are transforming understanding of tropical forests and their biospheric role. Together we have discovered how, where and why forest carbon and biodiversity are responding to climate change, and how they feedback on it. This long-term pan-tropical collaboration has revealed a large long-term carbon sink and its trends, as well as making clear which drivers are most important, which forest processes are affected, where they are changing, what the lags are, and the likely future responses of tropical forests as the climate continues to change. By leveraging a remarkably old technology, plot networks are sparking a very modern revolution in tropical forest science. In the future, humanity can benefit greatly by nurturing the grassroots communities now collectively capable of generating unique, long-term understanding of Earth's most precious forests. Resumen: Los bosques tropicales son los ecosistemas más diversos y productivos del mundo y entender su funcionamiento es crítico para nuestro futuro colectivo. Sin embargo, hasta hace muy poco, los esfuerzos para medirlos y monitorearlos han estado muy desconectados. El trabajo en redes es esencial para descubrir las respuestas a preguntas que trascienden las fronteras y los plazos de las agencias de financiamiento. Aquí mostramos cómo una comunidad global está respondiendo a los desafíos de la investigación en ecosistemas tropicales a través de diversos equipos realizando mediciones árbol por árbol en miles de parcelas permanentes de largo plazo. Revisamos los descubrimientos más importantes de este trabajo y discutimos cómo este proceso está cambiando la ciencia relacionada a los bosques tropicales. El enfoque central de nuestro esfuerzo implica la conexión de iniciativas locales de largo plazo con protocolos estandarizados y manejo de datos para producir resultados que se puedan trasladar a múltiples escalas. Conectando investigadores tropicales, elevando su posición y estatus, nuestro modelo de Red Social de Investigación reconoce el rol fundamental que tienen, para el descubrimiento científico, quienes generan o producen los datos. Concebida en 1999 con RAINFOR (Suramérica), nuestras redes de parcelas permanentes han sido adaptadas en África (AfriTRON) y el sureste asiático (T-FORCES) y ampliamente replicadas en el mundo. Actualmente todas estas iniciativas están integradas a través de la ciber-infraestructura de ForestPlots.net, conectando colegas de 54 países en 24 redes diferentes de parcelas. Colectivamente, estas redes están transformando nuestro conocimiento sobre los bosques tropicales y el rol de éstos en la biósfera. Juntos hemos descubierto cómo, dónde y porqué el carbono y la biodiversidad de los bosques tropicales está respondiendo al cambio climático y cómo se retroalimentan. Esta colaboración pan-tropical de largo plazo ha expuesto un gran sumidero de carbono y sus tendencias, mostrando claramente cuáles son los factores más importantes, qué procesos se ven afectados, dónde ocurren los cambios, los tiempos de reacción y las probables respuestas futuras mientras el clima continúa cambiando. Apalancando lo que realmente es una tecnología antigua, las redes de parcelas están generando una verdadera y moderna revolución en la ciencia tropical. En el futuro, la humanidad puede beneficiarse enormemente si se nutren y cultivan comunidades de investigadores de base, actualmente con la capacidad de generar información única y de largo plazo para entender los que probablemente son los bosques más preciados de la tierra. Resumo: Florestas tropicais são os ecossistemas mais diversos e produtivos da Terra. Embora uma boa compreensão destas florestas seja crucial para o nosso futuro coletivo, até muito recentemente os esforços de medições e monitoramento foram amplamente desconexos. É essencial formarmos redes para obtermos respostas que transcendem fronteiras e horizontes de agências financiadoras. Neste estudo nós mostramos como uma comunidade global está respondendo aos desafios da pesquisa de ecossistemas tropicais, com equipes diversas medindo florestas, árvore por árvore, em milhares de parcelas monitoradas à longo prazo. Nós revisamos as maiores descobertas científicas deste trabalho, e mostramos também como este processo está mudando a ciência de florestas tropicais. Nossa abordagem principal envolve unir iniciativas de base a protocolos padronizados e gerenciamento de dados a fim de gerar resultados robustos em escalas ampliadas. Ao conectar pesquisadores tropicais e elevar seus status, nosso modelo de Rede de Pesquisa Social reconhece o papel-chave do produtor dos dados na descoberta científica. Concebida em 1999 com o RAINFOR (América do Sul), nossa rede de parcelas permanentes foi adaptada para África (AfriTRON) e Sudeste asiático (T-FORCES), e tem sido extensamente reproduzida em todo o mundo. Agora estas múltiplas iniciativas estão integradas através de uma infraestrutura cibernética do ForestPlots.net, conectando colegas de 54 países de 24 redes de parcelas. Estas iniciativas estão transformando coletivamente o entendimento das florestas tropicais e seus papéis na biosfera. Juntos nós descobrimos como, onde e por que o carbono e a biodiversidade da floresta estão respondendo às mudanças climáticas, e seus efeitos de retroalimentação. Esta duradoura colaboração pantropical revelou um grande sumidouro de carbono persistente e suas tendências, assim como tem evidenciado quais direcionadores são mais importantes, quais processos florestais são mais afetados, onde eles estão mudando, seus atrasos no tempo de resposta, e as prováveis respostas das florestas tropicais conforme o clima continua a mudar. Dessa forma, aproveitando uma notável tecnologia antiga, redes de parcelas acendem faíscas de uma moderna revolução na ciência das florestas tropicais. No futuro a humanidade pode se beneficiar incentivando estas comunidades basais que agora são coletivamente capazes de gerar conhecimentos únicos e duradouros sobre as florestas mais preciosas da Terra. Résume: Les forêts tropicales sont les écosystèmes les plus diversifiés et les plus productifs de la planète. Si une meilleure compréhension de ces forêts est essentielle pour notre avenir collectif, jusqu'à tout récemment, les efforts déployés pour les mesurer et les surveiller ont été largement déconnectés. La mise en réseau est essentielle pour découvrir les réponses à des questions qui dépassent les frontières et les horizons des organismes de financement. Nous montrons ici comment une communauté mondiale relève les défis de la recherche sur les écosystèmes tropicaux avec diverses équipes qui mesurent les forêts arbre après arbre dans de milliers de parcelles permanentes. Nous passons en revue les principales découvertes scientifiques de ces travaux et montrons comment ce processus modifie la science des forêts tropicales. Notre approche principale consiste à relier les initiatives de base à long terme à des protocoles standardisés et une gestion de données afin de générer des résultats solides à grande échelle. En reliant les chercheurs tropicaux et en élevant leur statut, notre modèle de réseau de recherche sociale reconnaît le rôle clé de l'auteur des données dans la découverte scientifique. Conçus en 1999 avec RAINFOR (Amérique du Sud), nos réseaux de parcelles permanentes ont été adaptés à l'Afrique (AfriTRON) et à l'Asie du Sud-Est (T-FORCES) et largement imités dans le monde entier. Ces multiples initiatives sont désormais intégrées via l'infrastructure ForestPlots.net, qui relie des collègues de 54 pays à travers 24 réseaux de parcelles. Ensemble, elles transforment la compréhension des forêts tropicales et de leur rôle biosphérique. Ensemble, nous avons découvert comment, où et pourquoi le carbone forestier et la biodiversité réagissent au changement climatique, et comment ils y réagissent. Cette collaboration pan-tropicale à long terme a révélé un important puits de carbone à long terme et ses tendances, tout en mettant en évidence les facteurs les plus importants, les processus forestiers qui sont affectés, les endroits où ils changent, les décalages et les réactions futures probables des forêts tropicales à mesure que le climat continue de changer. En tirant parti d'une technologie remarquablement ancienne, les réseaux de parcelles déclenchent une révolution très moderne dans la science des forêts tropicales. À l'avenir, l'humanité pourra grandement bénéficier du soutien des communautés de base qui sont maintenant collectivement capables de générer une compréhension unique et à long terme des forêts les plus précieuses de la Terre. Abstrak: Hutan tropika adalah di antara ekosistem yang paling produktif dan mempunyai kepelbagaian biodiversiti yang tinggi di seluruh dunia. Walaupun pemahaman mengenai hutan tropika amat penting untuk masa depan kita, usaha-usaha untuk mengkaji dan mengawas hutah-hutan tersebut baru sekarang menjadi lebih diperhubungkan. Perangkaian adalah sangat penting untuk mencari jawapan kepada soalan-soalan yang menjangkaui sempadan dan batasan agensi pendanaan. Di sini kami menunjukkan bagaimana sebuah komuniti global bertindak balas terhadap cabaran penyelidikan ekosistem tropika melalui penglibatan pelbagai kumpulan yang mengukur hutan secara pokok demi pokok dalam beribu-ribu plot jangka panjang. Kami meninjau semula penemuan saintifik utama daripada kerja ini dan menunjukkan bagaimana proses ini sedang mengubah bidang sains hutan tropika. Teras pendekatan kami memberi tumpuan terhadap penghubungan inisiatif akar umbi jangka panjang dengan protokol standar serta pengurusan data untuk mendapatkan hasil skala besar yang kukuh. Dengan menghubungkan penyelidik-penyelidik tropika dan meningkatkan status mereka, model Rangkaian Penyelidikan Sosial kami mengiktiraf kepentingan peranan pengasas data dalam penemuan saintifik. Bermula dengan pengasasan RAINFOR (Amerika Selatan) pada tahun 1999, rangkaian-rangkaian plot kekal kami kemudian disesuaikan untuk Afrika (AfriTRON) dan Asia Tenggara (T-FORCES) dan selanjutnya telah banyak dicontohi di seluruh dunia. Kini, inisiatif-inisiatif tersebut disepadukan melalui infrastruktur siber ForestPlots.net yang menghubungkan rakan sekerja dari 54 negara di 24 buah rangkaian plot. Secara kolektif, rangkaian ini sedang mengubah pemahaman tentang hutan tropika dan peranannya dalam biosfera. Kami telah bekerjasama untuk menemukan bagaimana, di mana dan mengapa karbon serta biodiversiti hutan bertindak balas terhadap perubahan iklim dan juga bagaimana mereka saling bermaklum balas. Kolaborasi pan-tropika jangka panjang ini telah mendedahkan sebuah sinki karbon jangka panjang serta arah alirannya dan juga menjelaskan pemandu-pemandu perubahan yang terpenting, di mana dan bagaimana proses hutan terjejas, masa susul yang ada dan kemungkinan tindakbalas hutan tropika pada perubahan iklim secara berterusan di masa depan. Dengan memanfaatkan pendekatan lama, rangkaian plot sedang menyalakan revolusi yang amat moden dalam sains hutan tropika. Pada masa akan datang, manusia sejagat akan banyak mendapat manfaat jika memupuk komuniti-komuniti akar umbi yang kini berkemampuan secara kolektif menghasilkan pemahaman unik dan jangka panjang mengenai hutan-hutan yang paling berharga di dunia. Instituto de Ecología Regional (IER) Universidad Nacional de Tucumán (UNT) Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) Facultad de Ciencias Agrarias Universidad Nacional de Jujuy James Cook University (JCU) CSIRO (Commonwealth Scientific and Industrial Research Organisation) School of Land & Food University of Tasmania CSIRO Tropical Forest Research Centre Independent Researcher Environmental Protection Agency (EPA) Centre for Tropical Environmental and Sustainability Science (TESS) College of Marine and Environmental Sciences James Cook University Centre for Tropical Environmental and Sustainability Science College of Science and Engineering James Cook University University of the Sunshine Coast University of York Flamingo Land Ltd. Sommersbergseestrasse Ghent University CAVElab Ghent University Royal Museum for Central Africa - Service of Wood Biology Isotope Bioscience Laboratory-ISOFYS Ghent University Gembloux Agro-Bio Tech Université de Liege Landscape Ecology and Vegetal Production Systems Unit CAVElab Computational & Applied Vegetation Ecology Ghent University Tropical Forestry Forest Resources Management Gembloux Agro-Bio Tech University of Liege Université Libre de Bruxelles (ULB) Evolutionary Biology and Ecology Royal Museum for Central Africa Royal Museum for Central Africa Ghent University Department of Environment Ghent University Service Evolution Biologique et Ecologie Belize Foundation for Research and Environmental Education IBIF Museo de Historia Natural Noel Kempff Mercado Universidad Autonoma Gabriel Rene Moreno PROMAB Museo Noel Kempff Consultor Independiente Jardin Botanico Municipal de Santa Cruz Museo de Historia Natural Noel Kempff Mercado Forest Management in Bolivia Universidad Autónoma del Beni Riberalta Museo de Historia Natural Noel Kempff Herbario del Sur de Bolivia Universidad Autónoma del Beni Conservation International Instituto de Biodiversidade e Floresta Universidade Federal do Oeste do Pará Universidade Federal de Pernambuco Universidade do Estado de Mato Grosso Universidade do Estado de Mato Grosso (UNEMAT) Projeto TEAM – Manaus Universidade Federal de Juiz de Fora (UFJF) Universidade Federal do Rio de Janeiro Instituto Nacional de Pesquisas da Amazônia Projeto Dinâmica Biológica de Fragmentos Florestais Departamento de Genética Ecologia e Evolução Universidade Federal de Minas Gerais Universidade Estadual de Campinas Laboratório de Ecologia de Comunidades e Funcionamento de Ecossistemas-ECoFERP Departamento de Biologia Faculdade de Filosofia Ciências e Letras USP National Institute for Space Research (INPE) Universidade Federal de Roraima (UFRR) UNESP - São Paulo State University Carbonozero Consultoria Ambiental Departamento de Biologia Universidade Federal do Amazonas (UFAM) Centro de Energia Nuclear na Agricultura Universidade de São Paulo UERR - Campus Rorainópolis Universidade Federal do Acre Instituto Agronômico de Campinas Universidade Federal do Rio Grande do Sul Embrapa Universidade Estadual do Norte Fluminense (UENF) Universidade Federal da Bahia (UFBA) Instituto de Biologia Universidade Estadual de Campinas Universidade Federal do Piauí (UFPI) Botany and Plant Ecology Laboratory Federal University of Acre INPA- Instituto Nacional de Pesquisas da Amazônia UERR - Campus Boa Vista Universidade Federal do Ceará Universidade Federal de Campina Grande Universidade Federal do Para Núcleo de Estudos e Pesquisas Ambientais Universidade Estadual de Campinas Instituto Federal de Educação Ciência e Tecnologia do Acre Instituto de Pesquisas Jardim Botânico do Rio de Janeiro Universidade Federal do Oeste do Pará UEFS Depto. de Ciências Biológicas Universidade Federal do Agreste de Pernambuco (UFAPE) Universidade Estadual de Montes Claros FFCLRP-USP/Br UNEMAT Universidade Federal de Jataí Universidade Federal do Pará Instituto de Ciências Biológicas Universidade de Campinas Universidade Federal de Lavras (UFLA) Museu Goeldi Embrapa Amazônia Oriental Instituto Nacional de Pesquisas da Amazônia UFMG - Universidade Federal de Minas Gerais Fundação Universidade Fedral de Rondônia - UNIR INPA- Instituto Nacional de Pesquisas Amazônicas Instituto Nacional de Pesquisas da Amazônia - Coordenação de Pesquisas em Silvicultura Tropical Jardim Botânico do Rio de Janeiro National Institute for Research in Amazonia Universidade Federal de Roraima (UFRR/PRONAT) Universidade Estadual de Campinas/UNICAMP Instituto Nacional de Pesquisas da Amazônia/CPBO Universidade Federal de Santa Catarina (UFSC) INCAPER- Instituto Capixaba de Pesquisa Assistência Técnica e Extensão Rural INPE- Instituto Nacional de Pesquisas Espaciais Universidade de São Paulo Instituto de Biociências Universidade Estadual Paulista Semiarid National Institute (INSA) Universidade de Brasília Departamento de Engenharia Florestal IBAM - Instituto Bem Ambiental Universidade do Estado de Mato Grosso Campus de Nova Xavantina University in Campinas Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF) LMF Instituto Nacional de Pesquisas da Amazônia Universidade Federal do Vale do São Francisco USP - University of São Paulo Instituto Federal do Espírito Santo (IFES) INPA - Instituto Nacional de Pesquisas da Amazônia Grupo MAUA Universidade Federal de Mato Grosso Instituto de Ciências Naturais Humanas e Sociais Instituto Nacional da Mata Atlântica RAINFOR-PPBIO Universidade Federal Rural da Amazônia - UFRA/CAPES Universidade Federal do Amazonas (UFAM) INPA/Max-Planck Project EMBRAPA- Empresa Brasileira de Pesquisa Agropecuária (Amazônia Oriental) Serviço Florestal Brasileiro Museu Universitário Universidade Federal do Acre Universidade Federal Rural de Pernambuco PUCPR - Pontifícia Universidade Católica do Paraná Museu Paraense Emilio Goeldi Universiti Brunei Darussalam Environmental and Life Sciences Faculty of Science Universiti Brunei Darussalam Institute for Biodiversity and Environmental Research Universiti Brunei Darussalam Plant Systematic and Ecology Laboratory Department of Biology Higher Teachers’ Training College University of Yaounde I Faculty of Science Department of Botany and Plant Physiology University of Buea Faculty of Science Department of Plant Science University of Buea National Herbarium Plant Systematics and Ecology Laboratory Higher Teachers’ Training College University of Yaoundé I Department of Plant Biology Faculty of Sciences University of Yaounde 1 Bioversity International Faculty of Forestry University of Toronto Ministère des Eaux Forêts Chasse et Pêche (MEFCP) Universidad Católica de la Santísima Concepción Universidad de La Serena Research Institute of Tropical Forestry Chinese Academy of Forestry Kunming Institute of Botany Chinese Academy of Sciences Beijing Forestry University Universidad Nacional Abierta y a Distancia Red COL-TREE Corporación COL-TREE Nuevo Estándar Biotropical NEBIOT SAS Universidad del Tolima Asociación GAICA Universidad de Nariño – Red BST-Col Parques Nacionales Naturales Territorial Caribe – Red BST-Col Universidad del Atlantico – Red BST-Col Departamento de Ciencias Forestales Universidad Nacional de Colombia - Sede Medellín Socioecosistemas y Clima Sostenible Fundacion con Vida Parques Nacionales Naturales de Colombia – Red BST-Col Instituto de Investigación de Recursos Biológicos Alexander von Humboldt – Red BST-Col UNAL Instituto de Investigación Recursos Biologicos Alexander von Humboldt – Red BST-Col Fundación Jardín Botánico de Medellín Herbario “Joaquín Antonio Uribe” (JAUM) – Red BST-Col Universidad Nacional de Colombia sede Amazonia Coltree Facultad del Medio Ambiente y Recursos Naturales Universidad Distrital Francisco José de Caldas – Red BST-Col Universidad de Tolima Fundación Orinoquia Biodiversa – Red BST-Col Departamento de Biología Facultad de Ciencias Naturales Universidad Icesi – Red BST-Col Instituto de Ciencias Naturales Universidad Nacional de Colombia Universidad de los Llanos Servicios Ecoysistemicos y Cambio Climatico (SECC) Fundación Con Vida & Corporación COL-TREE Universidad del Rosario Fundacion Ecosistemas Secos de Colombia – Red BST-Col Universidad de los Andes - ANDES herbarium Institute of Botany Czech Academy of Sciences Palacky University Czech University of Life Sciences Mendel University World Wide Fund for Nature Wildlife Conservation Society-DR Congo Lukuru Wildlife Research Foundation Université de Kisangani Faculté des Sciences Laboratoire d'écologie et aménagement forestier Université de Kisangani Université de Kisangani Faculté des Sciences Agronomiques République Démocratique du Congo Ministère de l'Environnement et Développement Durable Aarhus University University of Copenhagen Escuela Politécnica Nacional del Ecuador Herbario Alfredo Paredes (QAP) Universidad Central del Ecuador Universidad Técnica Particular de Loja Grupo de Investigación en Biodiversidad Medio Ambiente y Salud-BIOMAS Universidad de las Américas, Campus Queri Keller Science Action Center The Field Museum, 1400 South Lake Shore Dr. Universidad Estatal Amazónica Facultad de Ingeniería Ambiental Universidad Tecnica del Norte Herbario Nacional del Ecuador Grupo de Ecosistemas Tropicales y Cambio Global Universidad Regional Amazónica ikiam Colegio de Ciencias Biológicas y Ambientales COCIBA & Extensión Galápagos Universidad San Francisco de Quito-USFQ Herbario de Botánica Económica del Ecuador QUSF Universidad San Francisco de Quito USFQ Galapagos Science Center USFQ UNC Chapel Hill University of North Carolina-UNC Chapel Hill University of Florida FindingSpecies Mekelle University Environment Climate Change and Coffee Forest Forum (ECCCFF) University of Turku Centre de coopération International en Recherche Agronomique pour le Développement (CIRAD) CNRS ONF INRAE Centre National de la Recherche Scientifique AMAP Univ Montpellier IRD CNRS CIRAD INRA Forêts et Sociétés (F&S) Centre de coopération International en Recherche Agronomique pour le Développement (CIRAD) Departement Hommes Natures Societes Museum national d'histoire naturelle INRA Cirad UMR Ecologie des Forêts de Guyane (AgroparisTech CNRS INRAE Université des Antilles Université de la Guyane) Ministry of Forests Seas Environment and Climate Rougier-Gabon Agence Nationale des Parcs Nationaux Gabon Commission of Central African Forests (COMIFAC) Agence Nationale des Parcs Nationaux Ministère des Forêts des Eaux de la Mer de l'Environnement Chargé du Plan Climat des Objectifs de Développement Durable et du Plan d'Affectation des Terres Institut de Recherche en Ecologie Tropicale (CENAREST) Gabon/Agence Nationale des Parcs Nationaux Georg-August-University Göttingen University of Freiburg Institute of Botany University of Hohenheim Max Planck Institute for Chemistry Forestry Research Institute of Ghana (FORIG) Mensuration Unit Forestry Commission of Ghana Center for International Forestry Research Iwokrama International Centre for Rainforest Conservation and Development Guyana Forestry Commission Utrecht University Centre for Sustainable Technologies Indian Institute of Science Centre for International Forestry Research (CIFOR) Herbarium Borgoriense Indonesian Institute of Sciences (LIPI) Indonesian Institute of Science Forest Research and Development Agency (FORDA) Balitek-KSDA Samboja University of Florence and MUSE - Museo delle Scienze Cirad Hokkaido University Graduate School of Agriculture Kyoto University Forestry Development Authority of the Government of Liberia (FDA) University of Liberia Sungai Wain Protection Forest South East Asia Rainforest Research Partnership Danum Valley Field Centre Malaysian Palm Oil Board Sabah Forestry Department Forest Research Centre Universiti Malaysia Sabah Sabah Forestry Department Sarawak Forestry Corporation Eduardo Mondlane University Herbarium UNAN-Leon Universidad Nacional Autónoma de Nicaragua University of Abeokuta Natural History Museum of Norway University of Oslo Norwegian University of Life Sciences Universidad Nacional de la Amazonía Peruana (UNAP) Universidad Nacional de Jaén Jardin Botanico de Missouri Andes to Amazon Biodiversity Program Universidad Nacional de San Agustín de Arequipa Facultad de Ciencias Biológicas Universidad Nacional de la Amazonía Peruana Kené - Instituto de Estudios Forestales y Ambientales Instituto de Investigaciones de la Amazonia Peruana (IIAP) Universidad Nacional Jorge Basadre de Grohmann (UNJBG) Universidad Nacional de San Antonio Abad del Cusco Centro de Conservación Investigación y Manejo CIMA Pontificia Universidad Católica del Perú Asociacion Bosques Perú Université Officielle de Bukavu Université Marien N'Gouabi Wildlife Conservation Society Ecole Nationale Supérieure d'Agronomie et de Foresterie Université Marien Ngouabi Univeriste Marien Ngouabi The Gola Rainforest National Park Department of Geography National University of Singapore Departamento de Biología y Geología Física y Química inorgánica Universidad Rey Juan Carlos Real Jardín Botánico – CSIC Departamento de Biología Área de Botánica Universidad Autónoma de Madrid Museo Nacional de Ciencias Naturales (MNCN-CSIC) Centre for Agricultural Research in Suriname (CELOS) Stockholm Environment Institute Department of Plant Ecology and Evolution Uppsala University Southern Swedish Forest Research Centre InfoFlora Conservatoire et Jardin Botanique Geneve National Chung Hsing University Sokoine University of Agriculture Naturalis Biodiversity Center Wageningen University Forest Ecology and Forest Management Group Tropenbos International Institute for Biodiversity and Ecosystem Dynamics University of Amsterdam Bureau Waardenburg BV Van Hall Larenstein University of Applied Sciences Van der Hout Forestry Consulting Utrecht University, Domplein 29 Wageningen University Plant Ecology and Nature Conservation Group Data for Sustainability Department of Zoology Entomology & Fisheries Sciences Makerere University The Institute of Tropical Forest Conservation (ITFC) Mbarara University of Science and Technology (MUST) George Washington University Makerere University Department of Forestry Biodiversity and Tourism Makerere University University of Stirling University of Kent School of Geography University of Leeds UK Centre of Ecology & Hydrology Lancaster University University of Oxford The Landscapes and Livelihoods Group (TLLG) Overseas Development Institute Manchester Metropolitan University University of Aberdeen University of Exeter School of GeoSciences University of Edinburgh University of Cambridge Department of Environment and Geography University of York Department of Geography University College London Imperial College School of Geography Earth & Environmental Sciences Birmingham Institute of Forest Research University of Birmingham University of Plymouth Geography College of Life and Environmental Sciences University of Exeter Lancaster Environment Centre Lancaster University University of Edinburgh School of Biology University of Leeds Royal Botanic Garden Edinburgh CENAREST & ANPN & Stirling University University of Bristol School of Biological Sciences Department of Plant Sciences University of Cambridge Living with Lake Centre Laurentian University Royal Botanic Gardens Kew The Royal Society for the Protection of Birds centre for Conservation Science Environmental Change Institute School of Geography and the Environment University of Oxford UK Centre for Ecology & Hydrology School of Geography and the Environment University of Oxford The Royal Botanic Gardens Department of Geography and Environmental Science University of Dundee School of Biological Sciences University of Southampton University of East Anglia Stirling University School of Earth and Environment University of Leeds Department of Plant & Soil Science School of Biological Sciences University of Aberdeen, Cruickshank Building Institute for Transport Studies University of Leeds UK Research & Innovation University of Nottingham University of Bangor Center for Tropical Research Institute of the Environment and Sustainability University of California Center for Tropical Conservation Nicholas School of the Environment Duke University Ecology and Evolutionary Biology University of Michigan Saint Louis Zoo Department of Organismic and Evolutionary Biology Harvard University Center for Global Discovery and Conservation Science Arizona State University Wildlife Conservation Society – Programme Congo Woods Hole Research Center The University of Michigan Herbarium Nicholas School of the Environment National Park Service University of California ForestGEO Smithsonian Tropical Research Institute University of Texas at Austin Smithsonian Institute Washington University in Saint Louis Center for Conservation and Sustainable Development at the Missouri Botanical Garden Smithsonian Tropical Research Institute Smithsonian Institution Forest Global Earth Observatory (ForestGEO) Forest Global Earth Observatory (ForestGEO) Smithsonian Tropical Research Institute George Mason University Missouri Botanical Garden Broward County Parks and Recreation Nova Southeastern University Science and Education The Field Museum Department of Biology Boston University Wake Forest University Department of Geographical Sciences University of Maryland San Diego Zoo Institute for Conservation Research Biology Department Washington State University Yale School of Forestry & Environmental Studies Columbia University Department of Environmental Science Policy and Management University of California Berkeley School of Earth Sciences and Environmental Sustainability Northern Arizona University Department of Geography and the Environment University of Texas at Austin UNELLEZ-Guanare Programa de Ciencias del Agro y el Mar Herbario Universitario (PORT) Ci Progress GreenLife Universidad Nacional Experimental de Guayana Instituto Venezolano de Investigaciones Científicas (IVIC) Universidad de los Andes Viet Nature Conservation Centre CIRAD School of Life Sciences University of Lincoln UNESP - São Paulo State University Instituto de Biociências Universidade Estadual Paulista Gordon and Betty Moore Foundation: 1656 FAPESP: 2012/51509-8 FAPESP: 2012/51872-5 Fundação de Amparo à Pesquisa do Estado de Goiás: 2017/10267000329 European Research Council: 291585 Gordon and Betty Moore Foundation: 5349 European Research Council: 758873 Belgian Federal Science Policy Office: BR/132/A1/AFRIFORD Belgian Federal Science Policy Office: BR/143/A3/HERBAXYLAREDD Vlaamse Interuniversitaire Raad: CD2018TEA459A103 CNPq: CNPq/PPBio/457602/2012-0 National Science Foundation: DEB 1754647 Natural Environment Research Council: E/M0022021/1 Royal Society: ICA/R1/180100 Natural Environment Research Council: NE/D005590/1 European Research Council: NE/F005806/1 Natural Environment Research Council: NE/F005806/1 FAPESP: NE/K016431/1 Natural Environment Research Council: NE/N004655/1 FAPESP: NE/N012542/1 Royal Society: NE/P008755/1 FAPESP: NE/S011811/1 National Geographic Society: NE/T01279X/1 CNPq: PELD/441244/2016-5 Belgian Federal Science Policy Office: SD/AR/01A/COBIMFO

Three decades of satellite observations provide unprecedented information about forest change trajectories in the humid tropics., Accurate characterization of tropical moist forest changes is needed to support conservation policies and to quantify their contribution to global carbon fluxes more effectively. We document, at pantropical scale, the extent and changes (degradation, deforestation, and recovery) of these forests over the past three decades. We estimate that 17% of tropical moist forests have disappeared since 1990 with a remaining area of 1071 million hectares in 2019, from which 10% are degraded. Our study underlines the importance of the degradation process in these ecosystems, in particular, as a precursor of deforestation, and in the recent increase in tropical moist forest disturbances (natural and anthropogenic degradation or deforestation). Without a reduction of the present disturbance rates, undisturbed forests will disappear entirely in large tropical humid regions by 2050. Our study suggests that reinforcing actions are needed to prevent the initial degradation that leads to forest clearance in 45% of the cases.

International audience; Woody vegetation dynamics in the Sahel have been debated since the great droughts of the 1970s–1980s. Here, we combined high-resolution satellite and aerial imagery, field inventory, and historical botanical records to study woody vegetation trends over the years 1965, 1980, 2008, and 2018 in the Ferlo, the Sahelian sylvo-pastoral zone of Senegal. While tree density has decreased from 1965 (14.8 trees ha−1) to 1980 (13.4 trees ha−1) and 2008 (11.9 trees ha−1), tree density has stabilized in 2018 (12.2 trees ha−1). The relatively moderate decrease in tree density over 50 years characterized by extensive human pressure and droughts, as well as the rather stable woody cover following the drought years after the 1980s, do not support narratives of widespread desertification in this region. However, we observed a shift in the composition of species. While the drought-resistant tree Balanites aegyptiaca showed a stable abundance, Acacia tortilis showed strong increases and other species like Sclerocarya birrea and Combretum glutinosum decreased. In addition, recent field surveys show that the ratio between shrubs and trees has increased towards more shrubs. The observed loss of species diversity combined with the increase of drought-resistant species is in line with current observations for savanna ecosystems in the context of an increased aridity.

Small reservoirs (SRs) are essential water storage infrastructures for rural populations of Sub-Saharan West Africa. In recent years, rapid population increase has resulted in unprecedented land use and land cover (LULC) changes. Our study documents the impacts of such changes on the water quality of SRs in Burkina Faso. Multi-temporal Landsat images were analyzed to determine LULC evolutions at various scales between 2002 and 2014. Population densities were calculated from downloaded 2014 population data. In situ water samples collected in 2004/5 and 2014 from selected SRs were analyzed for Suspended Particulate Matter (SPM) loads, an integrative proxy for water quality. The expansion of crop and artificial areas at the expense of natural covers controlled LULC changes over the period. We found a very significant correlation between SPM loads and population densities calculated at a watershed scale. A general increase between the two sampling dates in the inorganic component of SPM loads, concomitant with a clear expansion of cropland areas at a local scale, was evidenced. Results of the study suggest that two complementary but independent indicators (i.e., LULC changes within 5-km buffer areas around SRs and demographic changes at watershed scale), relevantly reflected the nature and intensity of overall pressures exerted by humans on their environment, and locally on aquatic ecosystems. Recommendations related to the re-greening of peripheral areas around SRs in order to protect water bodies are suggested.

International audience; To allow for the production of timber while preserving conservation values, forestry regulations in the Congo Basin have made Forest Management Plans (FMP) mandatory in logging concessions. This paper uses original high-resolution maps of forest-cover changes and official records on the activities of logging concessions to analyze the impact of FMP on deforestation in this region. We apply quasi-experimental and difference-indifference approaches to evaluate the change in deforestation in concessions managed under an approved FMP. We find that between 2000 and 2010, deforestation was 74% lower in concessions with an FMP compared to others. Building on a theory of change, further analyses revealed that this decrease in deforestation takes time to occur and is highest around communities located in and nearby logging concessions, and in areas close to previous deforestation. These findings suggest that FMP help avoid deforestation by allowing logging companies to rotate cycles of timber extraction, thereby avoiding the overexploitation of areas that were previously logged, and by the better regulation of access to concessions by closing former logging roads to limit illegal activities such as shifting agriculture, hunting and the illegal harvest of timber or fuel-wood.

International audience; In a context of fast land changes due to human activity, the old 'Malthus vs. Boserup' debate about human pressure on natural resources is more than ever a prevalent subject. We illustrate this debate with an example based on the Tuy Province in West Burkina Faso, which has known an important development these last fifteen years, as mainly observable in the major regression of its natural vegetation. The objective of this article is to question the possible future scenarios of this region, by using a spatial model to understand past land change mechanisms and prospect plausible future ways of development. In particular, the spatial model describes the vegetation clearance processes identified during field campaigns, which we used to draw prospective scenarios and assess their possible effect on natural vegetation evolution. The processing of remote sensing images helped us reveal that one quarter of the total study area was cleared during the last fourteen years. Surveys carried out in the field enabled the identification of the three main processes responsible for these changes: farm size expansion, creation of new farms due to family nuclearization and migrant settlement. The model was then built to reproduce these three processes, and was validated by comparison with the land use classification of remote sensing images. Our model was also used to explore past clearance mechanisms: we found that 90% of the clearance was shared equally between farm size expansion and nuclearization processes, the settlement of migrants being responsible for less than 10% of the clearance. Model outputs also showed a shift in the clearance schemes compared to ancient practices: land characteristics are no longer considered when land is cleared and now clearance also occurs in neighbouring villages with available lands. These results suggest that the region has finally evolved similarly to a Malthusian rationale, even if the past dynamics resulted from a complex combination of factors. Finally, we analysed several prospective scenarios to assess the impacts of i) different population evolutions (normal demographic growth, emigrations and demographic regulation), ii) the implementation of protected areas in each village, iii) an intensification of farming systems. Two possible solutions for reducing natural vegetation clearance in the region are discussed: Emigration to other regions or a demographic regulation accompanied with an intensification of agricultural systems. However, the question remains whether such changes can be accomplished rapidly enough to abate the pressing natural vegetation decrease threat and to maintain an acceptable livelihood in the region.

International audience; A wide range of environmental and societal issues such as food security policy implementation requires accurate information on biomass productivity and its underlying drivers at both regional and local scales. While many studies in West Africa are conducted with coarse resolution earth observation data, few have tried to relate vegetation trends to explanatory factors, as is generally done in land use and land cover change (LULCC) studies at finer scales. In this study, we proposed to make a bridge between vegetation trend analysis and LULCC studies to improve the understanding of the various factors that influence the biomass production changes observed in satellite time series (using integrated Normalized Difference Vegetation Index [NDVI] as a proxy). The study was conducted in two steps. In the first step, we analyzed MODIS NDVI linear trends together with TRMM growing season rainfall over the Sahel region from 2000-2015. A classification scheme was proposed that enables better specification of the relative role of the main drivers of biomass production dynamics. We found that 16% of the Sahel is re-greening-but found strong evidence that rainfall is not the only important driver of biomass increase. Moreover, a decrease found in 5% of the Sahel can be chiefly attributed to factors other than rainfall (88%). In the second step, we focused on the "Degré Carré de Niamey" site in Niger. Here, the observed biomass trends were analyzed in relation to land cover changes and a set of potential drivers of LULCC using the Random Forest algorithm. We observed negative trends (29% of the Niger site area) mainly in tiger bush areas located on lateritic plateaus, which are particularly prone to pressures from overgrazing and overlogging. The significant role of accessibility factors in biomass production trends was also highlighted. Our methodological framework may be used to highlight changing areas and their major drivers to identify target areas for more detailed studies. Finer-scale assessments of the long-term vulnerability of populations can then be made to substantiate food security management policies.; De nombreux problèmes environnementaux et sociétaux, tels que la mise en œuvre de politiques de sécurité alimentaire, nécessitent des informations précises sur la productivité de la biomasse et ses facteurs sous-jacents aux niveaux régional et local. Alors que de la plupart des études en Afrique de l’Ouest reposent sur des données d’observation de la Terre à faible résolution spatiale, peu d’entre elles ont tenté de relier les tendances de la production végétale à des facteurs explicatifs, comme c’est généralement le cas dans les études sur le changement d'utilisation et d'occupation des sols (LULCC) à des échelles plus fines. Dans cette étude, nous avons proposé d'établir un pont entre l'analyse des tendances de la végétation et les études LULCC afin d'améliorer la compréhension des divers facteurs qui influencent les changements de production de biomasse observés dans les séries chronologiques satellites (en utilisant l'indice de végétation par différence normalisée [NDVI] intégré). L'étude a été réalisée en deux étapes. Dans un premier temps, nous avons analysé les tendances linéaires de MODIS NDVI ainsi que les précipitations TRMM, sur la région du Sahel, pendant la saison des pluies, de 2000 à 2015. Un système de classification a été proposé, qui permet de mieux préciser le rôle relatif des principaux facteurs de la dynamique de la production de biomasse. Nous avons constaté que 16% du Sahel est en train de reverdir, mais nous avons trouvé des indications solides que les précipitations ne sont pas le seul facteur important d'augmentation de la biomasse. De plus, une diminution constatée dans 5% du Sahel peut être principalement attribuée à des facteurs autres que les précipitations (88%). Dans un deuxième temps, nous nous sommes concentrés sur le site "Degré Carré de Niamey" au Niger. Ici, les tendances de la biomasse observées ont été analysées en relation avec les changements de l'occupation des sols et un ensemble de facteurs potentiels de LULCC, avec l'algorithme Random Forest. Nous avons observé des tendances négatives (29% de la superficie du site du Niger) principalement dans les zones de brousses tigrées situées sur des plateaux latéritiques, particulièrement sujettes aux pressions dues au surpâturage et à la surexploitation. Le rôle important des facteurs d’accessibilité dans les tendances de la production de biomasse a également été mis en évidence. Notre cadre méthodologique peut être utilisé pour mettre en évidence les zones en évolution et leurs principaux moteurs afin d'identifier les zones cibles pour des études plus détaillées. Des évaluations plus précises de la vulnérabilité à long terme des populations peuvent ensuite être effectuées pour justifier les politiques de gestion de la sécurité alimentaire.

In this chapter, agricultural landscapes are defined as ecosystems used by humans for agricultural purposes (crop/livestock productions). Within the framework of climate land use and land cover evolution, which are sometimes responsible of significant impacts on the environment and societies, represent a major challenge for the international community. Monitoring of agricultural landscapes using remote sensing images takes place within a larger scientific framework on the study of land cover and land use changes in general. The Land Change Science, which has emerged over the last 10 years as a full-fledged scientific discipline, aims at understanding land cover and land use dynamics as a complex system based on the humankind-environment relationships, by developing theories, notions and models investigated in the framework of social and environmental sciences. These studies which focused in particular on the analysis of the interactions between land cover changes and global change in general (climate change, loss of biodiversity, impacts on natural resources…), and were developed within the framework of international research programs (LULCC: Land Use and Land Cover Change; GLP: Global Land Project, etc.), have four main objectives: – improving the characterization of the main types of land cover; – improving the identification of space-time dynamics that characterize land cover and land use changes (change dynamics, scales at which they occur, etc.); – identifying the main factors (spatial, biophysical, climatic, socioeconomic, etc.) that motivate land cover and land use changes; – improving and developing new models able to assess the impacts of land use and land cover changes on societies, territories and the environment.

Conversion of tropical forests to agriculture contributes significantly to global warming, causing an estimated 12-18% of global greenhouse gas (GHG) emissions. However, estimates of ecosystem carbon fluxes are not accurate mainly because of the limited understanding of their belowground components. Root dynamics, i.e. root production, mortality and decomposition, are crucial elements of ecosystem functioning; an understanding of root dynamics is required to estimate the carbon cycle accurately. This systematic review will assess the current evidence for how tropical and subtropical forest degradation and land-use changes to agriculture affects fine root dynamics. Several stages of forest degradation will be examined during the review process, including current agricultural conversion systems, such as oil palm plantations in Southeast Asia and soybean plantations and pastures in Latin America. The search strategy will follow a specific a priori review protocol. Searches will be conducted in English across six different scientific databases and Google Scholar will be used to ensure comprehensiveness of the evidence base. The retrieved articles will undergo a three-stage screening by title, abstract and full text using predefined inclusion/exclusion criteria. Screening consistency will be evaluated using kappa tests. From the final list of included studies, relevant information on fine root dynamics (i.e. rates and methods used), summary statistics (i.e. mean and variance), ecosystem (i.e. forest type or agricultural system), geographical location and climate and soil variables will be extracted and entered into a database. A meta-analysis will be conducted on subgroups such as root production, root mortality and root decomposition, to show how land-use change affects different components of fine root dynamics. The review will also synthesize the current methods used to assess fine root dynamics and discuss their methodological limitations and variances. (Resume d'auteur)

SummaryWhile around 20% of the Amazonian forest has been cleared for pastures and agriculture, one fourth of the remaining forest is dedicated to wood production [1]. Most of these production forests have been or will be selectively harvested for commercial timber, but recent studies show that even soon after logging, harvested stands retain much of their tree-biomass carbon and biodiversity [2,3]. Comparing species richness of various animal taxa among logged and unlogged forests across the tropics, Burivalova et al. [4] found that despite some variability among taxa, biodiversity loss was generally explained by logging intensity (the number of trees extracted). Here, we use a network of 79 permanent sample plots (376 ha total) located at 10 sites across the Amazon Basin [5] to assess the main drivers of time-to-recovery of post-logging tree carbon (Table S1). Recovery time is of direct relevance to policies governing management practices (i.e., allowable volumes cut and cutting cycle lengths), and indirectly to forest-based climate change mitigation interventions.

International audience; The Indochinese section of the Mekong Basin has been subjected to major environmental disturbances over the last half century. The Vietnam War is invoked as a central explanation for the extensive deforestation in specific areas while conflictinduced exoduses caused the abandonment of cultivated lands, followed by forest regeneration. Although the socio-economical consequences of these episodes have been analysed, their hydrological impacts remain unknown. This paper investigates hydrological changes in two catchments of the lower Mekong Basin that were either heavily bombed (in southern Laos) or depopulated (in northern Laos). This analysis is based on the widely and independently recognized fact that vegetation, via evapotranspiration, is a central driver of basin water yield. The analysis of the most complete Vietnam War air mission database and of available hydro-meteorological data over the period 1960–2004 reveals a sharp runoff increase in the southern catchment when bombing climaxed in the early 1970s while no hydrological change is observed in the northern catchment over the same period. From 1995 onwards, the northern and southern catchment's runoff productions are significantly lower and higher than in the pre-war conditions, respectively. Although causalities could not be ascertained because of data limitations, these short- and long-term hydrological shifts were found to be consistent, in terms of occurrence, spatial distribution and magnitude, with the expected changes in the vegetation cover, either denser in the north (in response to abandonment of cultivated lands) or sparser in the south (as a result of bomb-induced deforestation and soil degradations).