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Djiofack BY, Beeckman H, Bourland N, Belanganayi BL, Laurent F, Ilondea BA, Nsenga L, Huart A, Longwwango MM, Deklerck V, Lejeune G, Verbiest WWM, Van den Bulcke J, Van Acker J, De Mil T, Hubau W. Protecting an artificial savanna as a nature-based solution to restore carbon and biodiversity in the Democratic Republic of the Congo. GLOBAL CHANGE BIOLOGY 2024; 30:e17154. [PMID: 38273529 DOI: 10.1111/gcb.17154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 12/14/2023] [Accepted: 12/18/2023] [Indexed: 01/27/2024]
Abstract
A large share of the global forest restoration potential is situated in artificial 'unstable' mesic African savannas, which could be restored to higher carbon and biodiversity states if protected from human-induced burning. However, uncertainty on recovery rates in protected unstable savannas impedes science-informed forest restoration initiatives. Here, we quantify the forest restoration success of anthropogenic fire exclusion within an 88-ha mesic artificial savanna patch in the Kongo Central province of the Democratic Republic of the Congo (DR Congo). We found that aboveground carbon recovery after 17 years was on average 11.40 ± 0.85 Mg C ha-1 . Using a statistical model, we found that aboveground carbon stocks take 112 ± 3 years to recover to 90% of aboveground carbon stocks in old-growth forests. Assuming that this recovery trajectory would be representative for all unstable savannas, we estimate that they could have a total carbon uptake potential of 12.13 ± 2.25 Gt C by 2100 across DR Congo, Congo and Angola. Species richness recovered to 33.17% after 17 years, and we predicted a 90% recovery at 54 ± 2 years. In contrast, we predicted that species composition would recover to 90% of old-growth forest composition only after 124 ± 3 years. We conclude that the relatively simple and cost-efficient measure of fire exclusion in artificial savannas is an effective nature-based solution to climate change and biodiversity loss. However, more long-term and in situ monitoring efforts are needed to quantify variation in long-term carbon and diversity recovery pathways. Particular uncertainties are spatial variability in socio-economics and growing conditions as well as the effects of projected climate change.
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Affiliation(s)
- Brice Yannick Djiofack
- Royal Museum for Central Africa, Service of Wood Biology, Tervuren, Belgium
- Faculty of Bioscience Engineering, Department of Environment, Laboratory of Wood Technology (UGent-Woodlab), Ghent University, Gent, Belgium
- Wood Laboratory of Yangambi, Yangambi, DR Congo
| | - Hans Beeckman
- Royal Museum for Central Africa, Service of Wood Biology, Tervuren, Belgium
- Wood Laboratory of Yangambi, Yangambi, DR Congo
| | - Nils Bourland
- Royal Museum for Central Africa, Service of Wood Biology, Tervuren, Belgium
- Wood Laboratory of Yangambi, Yangambi, DR Congo
| | - Basile Luse Belanganayi
- Royal Museum for Central Africa, Service of Wood Biology, Tervuren, Belgium
- Wood Laboratory of Yangambi, Yangambi, DR Congo
- Forest is Life, TERRA Teaching and Research Centre, Gembloux Agro Bio-Tech, University of Liège, Gembloux, Belgium
| | - Félix Laurent
- Royal Museum for Central Africa, Service of Wood Biology, Tervuren, Belgium
- Faculty of Bioscience Engineering, Department of Environment, Laboratory of Wood Technology (UGent-Woodlab), Ghent University, Gent, Belgium
- Wood Laboratory of Yangambi, Yangambi, DR Congo
| | | | | | | | | | - Victor Deklerck
- Royal Botanic Gardens Kew, Richmond, UK
- Meise Botanic Garden, Meise, Belgium
| | | | - William W M Verbiest
- Faculty of Bioscience Engineering, Department of Environment, Laboratory of Wood Technology (UGent-Woodlab), Ghent University, Gent, Belgium
| | - Jan Van den Bulcke
- Faculty of Bioscience Engineering, Department of Environment, Laboratory of Wood Technology (UGent-Woodlab), Ghent University, Gent, Belgium
| | - Joris Van Acker
- Faculty of Bioscience Engineering, Department of Environment, Laboratory of Wood Technology (UGent-Woodlab), Ghent University, Gent, Belgium
| | - Tom De Mil
- Forest is Life, TERRA Teaching and Research Centre, Gembloux Agro Bio-Tech, University of Liège, Gembloux, Belgium
| | - Wannes Hubau
- Royal Museum for Central Africa, Service of Wood Biology, Tervuren, Belgium
- Faculty of Bioscience Engineering, Department of Environment, Laboratory of Wood Technology (UGent-Woodlab), Ghent University, Gent, Belgium
- Wood Laboratory of Yangambi, Yangambi, DR Congo
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Gallup SM, Baker IT, Gallup JL, Restrepo‐Coupe N, Haynes KD, Geyer NM, Denning AS. Accurate Simulation of Both Sensitivity and Variability for Amazonian Photosynthesis: Is It Too Much to Ask? JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS 2021; 13:e2021MS002555. [PMID: 34594478 PMCID: PMC8459247 DOI: 10.1029/2021ms002555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 07/22/2021] [Accepted: 07/28/2021] [Indexed: 06/13/2023]
Abstract
Estimates of Amazon rainforest gross primary productivity (GPP) differ by a factor of 2 across a suite of three statistical and 18 process models. This wide spread contributes uncertainty to predictions of future climate. We compare the mean and variance of GPP from these models to that of GPP at six eddy covariance (EC) towers. Only one model's mean GPP across all sites falls within a 99% confidence interval for EC GPP, and only one model matches EC variance. The strength of model response to climate drivers is related to model ability to match the seasonal pattern of the EC GPP. Models with stronger seasonal swings in GPP have stronger responses to rain, light, and temperature than does EC GPP. The model to data comparison illustrates a trade-off inherent to deterministic models between accurate simulation of a mean (average) and accurate responsiveness to drivers. The trade-off exists because all deterministic models simplify processes and lack at least some consequential driver or interaction. If a model's sensitivities to included drivers and their interactions are accurate, then deterministically predicted outcomes have less variability than is realistic. If a GPP model has stronger responses to climate drivers than found in data, model predictions may match the observed variance and seasonal pattern but are likely to overpredict GPP response to climate change. High or realistic variability of model estimates relative to reference data indicate that the model is hypersensitive to one or more drivers.
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Affiliation(s)
- Sarah M. Gallup
- Graduate Degree Program in EcologyColorado State UniversityFort CollinsCOUSA
| | - Ian T. Baker
- Department of Atmospheric ScienceColorado State UniversityFort CollinsCOUSA
| | - John L. Gallup
- Department of EconomicsPortland State UniversityPortlandORUSA
| | - Natalia Restrepo‐Coupe
- Department of Ecology and Evolutionary BiologyUniversity of ArizonaTucsonAZUSA
- School of Life SciencesUniversity of Technology SydneyUltimoNSWAustralia
| | | | - Nicholas M. Geyer
- Department of Atmospheric ScienceColorado State UniversityFort CollinsCOUSA
| | - A. Scott Denning
- Graduate Degree Program in EcologyColorado State UniversityFort CollinsCOUSA
- Department of Atmospheric ScienceColorado State UniversityFort CollinsCOUSA
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Ecosystem Productivity and Water Stress in Tropical East Africa: A Case Study of the 2010–2011 Drought. LAND 2019. [DOI: 10.3390/land8030052] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Characterizing the spatiotemporal patterns of ecosystem responses to drought is important in understanding the impact of water stress on tropical ecosystems and projecting future land cover transitions in the East African tropics. Through the analysis of satellite measurements of solar-induced chlorophyll fluorescence (SIF) and the normalized difference vegetation index (NDVI), soil moisture, rainfall, and reanalysis data, here we characterize the 2010–2011 drought in tropical East Africa. The 2010–2011 drought included the consecutive failure of rainy seasons in October–November–December 2010 and March–April–May 2011 and extended further east and south compared with previous regional droughts. During 2010–2011, SIF, a proxy of ecosystem productivity, showed a concomitant decline (~32% lower gross primary productivity, or GPP, based on an empirical SIF–GPP relationship, as compared to the long-term average) with water stress, expressed by lower precipitation and soil moisture. Both SIF and NDVI showed a negative response to drought, and SIF captured the response to soil moisture with a lag of 16 days, even if it had lower spatial resolution and much smaller energy compared with NDVI, suggesting that SIF can also serve as an early indicator of drought in the future. This work demonstrates the unique characteristics of the 2010–2011 East African drought and the ability of SIF and NDVI to track the levels of water stress during the drought.
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Feldman AF, Short Gianotti DJ, Konings AG, McColl KA, Akbar R, Salvucci GD, Entekhabi D. Moisture pulse-reserve in the soil-plant continuum observed across biomes. NATURE PLANTS 2018; 4:1026-1033. [PMID: 30518832 DOI: 10.1038/s41477-018-0304-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 10/15/2018] [Indexed: 06/09/2023]
Abstract
The degree to which individual pulses of available water drive plant activity across diverse biomes and climates is not well understood. It has previously only been investigated in a few dryland locations. Here, plant water uptake following pulses of surface soil moisture, an indicator for the pulse-reserve hypothesis, is investigated across South America, Africa and Australia with satellite-based estimates of surface soil and canopy water content. Our findings show that this behaviour is widespread: occurring over half of the vegetated landscapes. We estimate spatially varying soil moisture thresholds at which plant water uptake ceases, noting dependence on soil texture and proximity to the wilting point. The soil type and biome-dependent soil moisture threshold and the plant soil water uptake patterns at the scale of Earth system models allow a unique opportunity to test and improve model parameterization of vegetation function under water limitation.
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Affiliation(s)
- Andrew F Feldman
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
| | - Daniel J Short Gianotti
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Alexandra G Konings
- Department of Earth System Science, Stanford University, Stanford, California, USA
| | - Kaighin A McColl
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Ruzbeh Akbar
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Guido D Salvucci
- Department of Earth and Environment, Boston University, Boston, MA, USA
| | - Dara Entekhabi
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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Wollenberg Valero KC, Isokpehi RD, Douglas NE, Sivasundaram S, Johnson B, Wootson K, McGill A. Plant Phenology Supports the Multi-emergence Hypothesis for Ebola Spillover Events. ECOHEALTH 2018; 15:497-508. [PMID: 29134435 PMCID: PMC6245028 DOI: 10.1007/s10393-017-1288-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 10/09/2017] [Accepted: 10/26/2017] [Indexed: 06/07/2023]
Abstract
Ebola virus disease outbreaks in animals (including humans and great apes) start with sporadic host switches from unknown reservoir species. The factors leading to such spillover events are little explored. Filoviridae viruses have a wide range of natural hosts and are unstable once outside hosts. Spillover events, which involve the physical transfer of viral particles across species, could therefore be directly promoted by conditions of host ecology and environment. In this report, we outline a proof of concept that temporal fluctuations of a set of ecological and environmental variables describing the dynamics of the host ecosystem are able to predict such events of Ebola virus spillover to humans and animals. We compiled a data set of climate and plant phenology variables and Ebola virus disease spillovers in humans and animals. We identified critical biotic and abiotic conditions for spillovers via multiple regression and neural network-based time series regression. Phenology variables proved to be overall better predictors than climate variables. African phenology variables are not yet available as a comprehensive online resource. Given the likely importance of phenology for forecasting the likelihood of future Ebola spillover events, our results highlight the need for cost-effective transect surveys to supply phenology data for predictive modelling efforts.
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Affiliation(s)
| | - Raphael D Isokpehi
- Department of Natural Sciences, College of Science, Engineering and Mathematics, Bethune-Cookman University, Daytona Beach, FL, USA
| | - Noah E Douglas
- Department of Natural Sciences, College of Science, Engineering and Mathematics, Bethune-Cookman University, Daytona Beach, FL, USA
| | - Seenith Sivasundaram
- Department of Mathematics and Physics, College of Science, Engineering and Mathematics, Bethune-Cookman University, Daytona Beach, FL, USA
| | - Brianna Johnson
- Department of Natural Sciences, College of Science, Engineering and Mathematics, Bethune-Cookman University, Daytona Beach, FL, USA
| | - Kiara Wootson
- Department of Mathematics and Physics, College of Science, Engineering and Mathematics, Bethune-Cookman University, Daytona Beach, FL, USA
| | - Ayana McGill
- Department of Natural Sciences, College of Science, Engineering and Mathematics, Bethune-Cookman University, Daytona Beach, FL, USA
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Abernethy K, Bush ER, Forget PM, Mendoza I, Morellato LPC. Current issues in tropical phenology: a synthesis. Biotropica 2018. [DOI: 10.1111/btp.12558] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Katharine Abernethy
- Biological and Environmental Sciences; University of Stirling; Stirling UK
- Institut de Recherches en Ecologie Tropicale; CENAREST; Libreville Gabon
| | - Emma R. Bush
- Biological and Environmental Sciences; University of Stirling; Stirling UK
| | - Pierre-Michel Forget
- Museum National d'Histoire Naturelle; Department Adaptations du Vivant; UMR MECADEV 7179 CNRS-MNHN; Brunoy France
| | - Irene Mendoza
- Laboratório de Fenologia; Departamento de Botânica; Instituto de Biociências; Universidade Estadual Paulista UNESP; Rio Claro, São Paulo Brasil
| | - Leonor Patricia C. Morellato
- Laboratório de Fenologia; Departamento de Botânica; Instituto de Biociências; Universidade Estadual Paulista UNESP; Rio Claro, São Paulo Brasil
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Land use change and El Niño-Southern Oscillation drive decadal carbon balance shifts in Southeast Asia. Nat Commun 2018; 9:1154. [PMID: 29559637 PMCID: PMC5861034 DOI: 10.1038/s41467-018-03374-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 02/05/2018] [Indexed: 11/08/2022] Open
Abstract
An integrated understanding of the biogeochemical consequences of climate extremes and land use changes is needed to constrain land-surface feedbacks to atmospheric CO2 from associated climate change. Past assessments of the global carbon balance have shown particularly high uncertainty in Southeast Asia. Here, we use a combination of model ensembles to show that intensified land use change made Southeast Asia a strong source of CO2 from the 1980s to 1990s, whereas the region was close to carbon neutral in the 2000s due to an enhanced CO2 fertilization effect and absence of moderate-to-strong El Niño events. Our findings suggest that despite ongoing deforestation, CO2 emissions were substantially decreased during the 2000s, largely owing to milder climate that restores photosynthetic capacity and suppresses peat and deforestation fire emissions. The occurrence of strong El Niño events after 2009 suggests that the region has returned to conditions of increased vulnerability of carbon stocks. The carbon balance in Southeast Asia is highly uncertain. Here, the authors show that land use changes and occurrence of strong El Niño control decadal shifts in the carbon balance of this region.
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Drought Effects on Photosynthesis and Implications of Photoassimilate Distribution in 11C-Labeled Leaves in the African Tropical Tree Species Maesopsis eminii Engl. FORESTS 2018. [DOI: 10.3390/f9030109] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Van Camp J, Hubeau M, Van den Bulcke J, Van Acker J, Steppe K. Cambial pinning relates wood anatomy to ecophysiology in the African tropical tree Maesopsis eminii. TREE PHYSIOLOGY 2018; 38:232-242. [PMID: 29194496 DOI: 10.1093/treephys/tpx151] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 11/01/2017] [Indexed: 06/07/2023]
Abstract
A better understanding and prediction of the impact of changing climate on tree stem growth could greatly benefit from the combination of anatomical and ecophysiological knowledge, yet the majority of studies focus on one research field only. We propose an approach that combines the method of pinning (cambial wounding) to timestamp anatomical X-ray computed microtomography images with continuous measurements of sap flow and stem diameter variations. By pinning the cambium of well-watered and drought-treated young African tropical trees of the species Maesopsis eminii Engl. we could quantify wood formation during a specific period of time and relate it to tree physiology and prevailing microclimate. Integrating continuous plant measurements and high-frequency pinning proved very useful to visualize and quantify the effects on stem growth of drought in M. eminii. Wood formation completely stopped during drought, and was associated with a strong shrinkage in stem diameter. Next, an unexpected increase in stem diameter was observed during drought, probably caused by root pressure, but not accompanied by wood formation. Our proposed approach of combining continuous plant measurements with cambial pinning is very promising to relate ecophysiology to stem anatomy and to understand the mechanisms underlying tree stem growth and bridge the gaps between the two research fields.
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Affiliation(s)
- Janne Van Camp
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent 9000, Belgium
| | - Michiel Hubeau
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent 9000, Belgium
| | - Jan Van den Bulcke
- UGCT-Woodlab-UGent, Laboratory of Wood Technology, Department of Environment, Faculty of Bioscience Engineering, Ghent University, Ghent 9000, Belgium
| | - Joris Van Acker
- UGCT-Woodlab-UGent, Laboratory of Wood Technology, Department of Environment, Faculty of Bioscience Engineering, Ghent University, Ghent 9000, Belgium
| | - Kathy Steppe
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent 9000, Belgium
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Liu J, Bowman KW, Schimel DS, Parazoo NC, Jiang Z, Lee M, Bloom AA, Wunch D, Frankenberg C, Sun Y, O’Dell CW, Gurney KR, Menemenlis D, Gierach M, Crisp D, Eldering A. Contrasting carbon cycle responses of the tropical continents to the 2015–2016 El Niño. Science 2017; 358:358/6360/eaam5690. [DOI: 10.1126/science.aam5690] [Citation(s) in RCA: 240] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 07/06/2017] [Indexed: 11/02/2022]
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Ago EE, Serça D, Agbossou EK, Galle S, Aubinet M. Carbon dioxide fluxes from a degraded woodland in West Africa and their responses to main environmental factors. CARBON BALANCE AND MANAGEMENT 2015; 10:22. [PMID: 26413151 PMCID: PMC4573653 DOI: 10.1186/s13021-015-0033-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 08/25/2015] [Indexed: 06/05/2023]
Abstract
BACKGROUND In West Africa, natural ecosystems such as woodlands are the main source for energy, building poles and livestock fodder. They probably behave like net carbon sinks, but there are only few studies focusing on their carbon exchange with the atmosphere. Here, we have analyzed CO2 fluxes measured for 17 months by an eddy-covariance system over a degraded woodland in northern Benin. Specially, temporal evolution of the fluxes and their relationships with the main environmental factors were investigated between the seasons. RESULTS This study shows a clear response of CO2 absorption to photosynthetic photon flux density (Qp), but it varies according to the seasons. After a significant and long dry period, the ecosystem respiration (R) has increased immediately to the first significant rains. No clear dependency of ecosystem respiration on temperature has been observed. The degraded woodlands are probably the "carbon neutral" at the annual scale. The net ecosystem exchange (NEE) was negative during wet season and positive during dry season, and its annual accumulation was equal to +29 ± 16 g C m-2. The ecosystem appears to be more efficient in the morning and during the wet season than in the afternoon and during the dry season. CONCLUSIONS This study shows diurnal and seasonal contrasted variations in the CO2 fluxes in relation to the alternation between dry and wet seasons. The Nangatchori site is close to the equilibrium state according to its carbon exchanges with the atmosphere. The length of the observation period was too short to justify the hypothesis about the "carbon neutrality" of the degraded woodlands at the annual scale in West Africa. Besides, the annual net ecosystem exchange depends on the intensity of disturbances due to the site management system. Further research works are needed to define a woodland management policy that might keep these ecosystems as carbon sinks.
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Affiliation(s)
- Expedit Evariste Ago
- Axe Exchange Ecosystems-Atmosphere, Department of Biosystem Engineering (BIOSE), University of Liege, Gembloux Agro Bio Tech, 8, Avenue de la Faculté, 5030 Gembloux, Belgium
- Laboratoire d’Hydraulique et de Maîtrise de l’Eau, Faculté des Sciences Agronomiques (FSA), Université d’Abomey-Calavi (UAC), BP 2819, Cotonou, Benin
| | - Dominique Serça
- Laboratoire d’Aérologie, UMR CNRS 5560, Université Paul Sabatier, Toulouse, France
| | - Euloge Kossi Agbossou
- Laboratoire d’Hydraulique et de Maîtrise de l’Eau, Faculté des Sciences Agronomiques (FSA), Université d’Abomey-Calavi (UAC), BP 2819, Cotonou, Benin
| | - Sylvie Galle
- Univ. Grenoble Alpes, LTHE, 38000 Grenoble, France
- CNRS LTHE, 38000 Grenoble, France
- IRD, LTHE, 38000 Grenoble, France
| | - Marc Aubinet
- Axe Exchange Ecosystems-Atmosphere, Department of Biosystem Engineering (BIOSE), University of Liege, Gembloux Agro Bio Tech, 8, Avenue de la Faculté, 5030 Gembloux, Belgium
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Ardö J. Comparison between remote sensing and a dynamic vegetation model for estimating terrestrial primary production of Africa. CARBON BALANCE AND MANAGEMENT 2015; 10:8. [PMID: 25960765 PMCID: PMC4412648 DOI: 10.1186/s13021-015-0018-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 03/18/2015] [Indexed: 06/04/2023]
Abstract
BACKGROUND Africa is an important part of the global carbon cycle. It is also a continent facing potential problems due to increasing resource demand in combination with climate change-induced changes in resource supply. Quantifying the pools and fluxes constituting the terrestrial African carbon cycle is a challenge, because of uncertainties in meteorological driver data, lack of validation data, and potentially uncertain representation of important processes in major ecosystems. In this paper, terrestrial primary production estimates derived from remote sensing and a dynamic vegetation model are compared and quantified for major African land cover types. RESULTS Continental gross primary production estimates derived from remote sensing were higher than corresponding estimates derived from a dynamic vegetation model. However, estimates of continental net primary production from remote sensing were lower than corresponding estimates from the dynamic vegetation model. Variation was found among land cover classes, and the largest differences in gross primary production were found in the evergreen broadleaf forest. Average carbon use efficiency (NPP/GPP) was 0.58 for the vegetation model and 0.46 for the remote sensing method. Validation versus in situ data of aboveground net primary production revealed significant positive relationships for both methods. A combination of the remote sensing method with the dynamic vegetation model did not strongly affect this relationship. CONCLUSION Observed significant differences in estimated vegetation productivity may have several causes, including model design and temperature sensitivity. Differences in carbon use efficiency reflect underlying model assumptions. Integrating the realistic process representation of dynamic vegetation models with the high resolution observational strength of remote sensing may support realistic estimation of components of the carbon cycle and enhance resource monitoring, providing suitable validation data is available.
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Affiliation(s)
- Jonas Ardö
- Department of Physical Geography and Ecosystem Science, Lund University, Sölvegatan 12, Lund, 223-62 Sweden
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Abstract
Feedbacks from the terrestrial carbon cycle significantly affect future climate change. The CO2 concentration dependence of global terrestrial carbon storage is one of the largest and most uncertain feedbacks. Theory predicts the CO2 effect should have a tropical maximum, but a large terrestrial sink has been contradicted by analyses of atmospheric CO2 that do not show large tropical uptake. Our results, however, show significant tropical uptake and, combining tropical and extratropical fluxes, suggest that up to 60% of the present-day terrestrial sink is caused by increasing atmospheric CO2. This conclusion is consistent with a validated subset of atmospheric analyses, but uncertainty remains. Improved model diagnostics and new space-based observations can reduce the uncertainty of tropical and temperate zone carbon flux estimates. This analysis supports a significant feedback to future atmospheric CO2 concentrations from carbon uptake in terrestrial ecosystems caused by rising atmospheric CO2 concentrations. This feedback will have substantial tropical contributions, but the magnitude of future carbon uptake by tropical forests also depends on how they respond to climate change and requires their protection from deforestation.
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Jones AG, Scullion J, Ostle N, Levy PE, Gwynn-Jones D. Completing the FACE of elevated CO₂ research. ENVIRONMENT INTERNATIONAL 2014; 73:252-8. [PMID: 25171551 DOI: 10.1016/j.envint.2014.07.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 07/26/2014] [Accepted: 07/28/2014] [Indexed: 05/12/2023]
Abstract
We appraise the present geographical extent and inherent knowledge limits, following two decades of research on elevated CO2 responses in plant communities, and ask whether such research has answered the key question in quantifying the limits of compensatory CO2 uptake in the major biomes. Our synthesis of all ecosystem-scale (between 10 m(2) and 3000 m(2) total experimental plot area) elevated CO2 (eCO2) experiments in natural ecosystems conducted worldwide since 1987 (n=151) demonstrates that the locations of these eCO2 experiments have been spatially biased, targeting primarily the temperate ecosystems of northern America and Europe. We consider the consequences, suggesting fundamentally that this limits the capacity of the research to understand how the world's major plant communities will respond to eCO2. Most notably, our synthesis shows that this research lacks understanding of impacts on tropical forests and boreal regions, which are potentially the most significant biomes for C sink and storage activity, respectively. Using a meta-analysis of the available data across all biomes, we show equivocal increases in net primary productivity (NPP) from eCO2 studies, suggesting that global validation is needed, especially in the most important biomes for C processing. Further, our meta-analysis identifies that few research programs have addressed eCO2 effects on below-ground C storage, such that at the global scale, no overall responses are discernable. Given the disparity highlighted in the distribution of eCO2 experiments globally, we suggest opportunities for newly-industrialized or developing nations to become involved in further research, particularly as these countries host some of the most important regions for tropical or sub-tropical forest systems. Modeling approaches that thus far have attempted to understand the biological response to eCO2 are constrained with respect to collective predictions, suggesting that further work is needed, which will link models to in situ eCO2 experiments, in order to understand how the world's most important regions for terrestrial C uptake and storage will respond to a future eCO2 atmosphere.
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Affiliation(s)
- Alan G Jones
- Institute of Biological Environmental and Rural Sciences, Aberystwyth University, Ceredigion, SY23 3DA, Wales, UK
| | - John Scullion
- Institute of Biological Environmental and Rural Sciences, Aberystwyth University, Ceredigion, SY23 3DA, Wales, UK
| | - Nick Ostle
- Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK
| | - Peter E Levy
- Centre for Ecology and Hydrology, Bush Estate, Penicuik, Midlothian, EH26 0QB, Scotland, UK
| | - Dylan Gwynn-Jones
- Institute of Biological Environmental and Rural Sciences, Aberystwyth University, Ceredigion, SY23 3DA, Wales, UK.
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15
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Multimodel projections and uncertainties of net ecosystem production in China over the twenty-first century. ACTA ACUST UNITED AC 2014. [DOI: 10.1007/s11434-014-0613-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Peng J, Dan L, Huang M. Sensitivity of global and regional terrestrial carbon storage to the direct CO2 effect and climate change based on the CMIP5 model intercomparison. PLoS One 2014; 9:e95282. [PMID: 24748331 PMCID: PMC3991598 DOI: 10.1371/journal.pone.0095282] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 03/26/2014] [Indexed: 11/18/2022] Open
Abstract
Global and regional land carbon storage has been significantly affected by increasing atmospheric CO2 concentration and climate change. Based on fully coupled climate-carbon-cycle simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5), we investigate sensitivities of land carbon storage to rising atmospheric CO2 concentration and climate change over the world and 21 regions during the 130 years. Overall, the simulations suggest that consistently spatial positive effects of the increasing CO2 concentrations on land carbon storage are expressed with a multi-model averaged value of 1.04PgC per ppm. The stronger positive values are mainly located in the broad areas of temperate and tropical forest, especially in Amazon basin and western Africa. However, large heterogeneity distributed for sensitivities of land carbon storage to climate change. Climate change causes decrease in land carbon storage in most tropics and the Southern Hemisphere. In these regions, decrease in soil moisture (MRSO) and enhanced drought somewhat contribute to such a decrease accompanied with rising temperature. Conversely, an increase in land carbon storage has been observed in high latitude and altitude regions (e.g., northern Asia and Tibet). The model simulations also suggest that global negative impacts of climate change on land carbon storage are predominantly attributed to decrease in land carbon storage in tropics. Although current warming can lead to an increase in land storage of high latitudes of Northern Hemisphere due to elevated vegetation growth, a risk of exacerbated future climate change may be induced due to release of carbon from tropics.
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Affiliation(s)
- Jing Peng
- START Temperate East Asia Regional Center and Key Laboratory of Regional Climate-Environment for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
| | - Li Dan
- START Temperate East Asia Regional Center and Key Laboratory of Regional Climate-Environment for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
- * E-mail:
| | - Mei Huang
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
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17
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Abernethy KA, Coad L, Taylor G, Lee ME, Maisels F. Extent and ecological consequences of hunting in Central African rainforests in the twenty-first century. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120303. [PMID: 23878333 PMCID: PMC3720024 DOI: 10.1098/rstb.2012.0303] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Humans have hunted wildlife in Central Africa for millennia. Today, however, many species are being rapidly extirpated and sanctuaries for wildlife are dwindling. Almost all Central Africa's forests are now accessible to hunters. Drastic declines of large mammals have been caused in the past 20 years by the commercial trade for meat or ivory. We review a growing body of empirical data which shows that trophic webs are significantly disrupted in the region, with knock-on effects for other ecological functions, including seed dispersal and forest regeneration. Plausible scenarios for land-use change indicate that increasing extraction pressure on Central African forests is likely to usher in new worker populations and to intensify the hunting impacts and trophic cascade disruption already in progress, unless serious efforts are made for hunting regulation. The profound ecological changes initiated by hunting will not mitigate and may even exacerbate the predicted effects of climate change for the region. We hypothesize that, in the near future, the trophic changes brought about by hunting will have a larger and more rapid impact on Central African rainforest structure and function than the direct impacts of climate change on the vegetation. Immediate hunting regulation is vital for the survival of the Central African rainforest ecosystem.
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Affiliation(s)
- K A Abernethy
- African Forest Ecology Group, School of Natural Sciences, University of Stirling, UK.
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18
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Malhi Y, Adu-Bredu S, Asare RA, Lewis SL, Mayaux P. African rainforests: past, present and future. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120312. [PMID: 23878339 PMCID: PMC3720030 DOI: 10.1098/rstb.2012.0312] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The rainforests are the great green heart of Africa, and present a unique combination of ecological, climatic and human interactions. In this synthesis paper, we review the past and present state processes of change in African rainforests, and explore the challenges and opportunities for maintaining a viable future for these biomes. We draw in particular on the insights and new analyses emerging from the Theme Issue on 'African rainforests: past, present and future' of Philosophical Transactions of the Royal Society B. A combination of features characterize the African rainforest biome, including a history of climate variation; forest expansion and retreat; a long history of human interaction with the biome; a relatively low plant species diversity but large tree biomass; a historically exceptionally high animal biomass that is now being severely hunted down; the dominance of selective logging; small-scale farming and bushmeat hunting as the major forms of direct human pressure; and, in Central Africa, the particular context of mineral- and oil-driven economies that have resulted in unusually low rates of deforestation and agricultural activity. We conclude by discussing how this combination of factors influences the prospects for African forests in the twenty-first century.
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Affiliation(s)
- Yadvinder Malhi
- Environmental Change Institute, School of Geography and the Environment, University of Oxford, UK.
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19
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Malhi Y, Adu-Bredu S, Asare RA, Lewis SL, Mayaux P. The past, present and future of Africa's rainforests. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120293. [PMID: 23878326 DOI: 10.1098/rstb.2012.0293] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Yadvinder Malhi
- Environmental Change Institute, School of Geography and the Environment, University of Oxford, UK.
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