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Guirado E, Delgado-Baquerizo M, Martínez-Valderrama J, Tabik S, Alcaraz-Segura D, Maestre FT. Climate legacies drive the distribution and future restoration potential of dryland forests. Nat Plants 2022; 8:879-886. [PMID: 35879606 PMCID: PMC7613308 DOI: 10.1038/s41477-022-01198-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 06/15/2022] [Indexed: 06/15/2023]
Abstract
Knowing the extent and environmental drivers of forests is key to successfully restore degraded ecosystems, and to mitigate climate change and desertification impacts using tree planting. Water availability is the main limiting factor for the development of forests in drylands, yet the importance of groundwater resources and palaeoclimate as drivers of their current distribution has been neglected. Here we report that mid-Holocene climates and aquifer trends are key predictors of the distribution of dryland forests worldwide. We also updated the global extent of dryland forests to 1,283 million hectares and showed that failing to consider past climates and aquifers has resulted in ignoring or misplacing up to 130 million hectares of forests in drylands. Our findings highlight the importance of a wetter past and well-preserved aquifers to explain the current distribution of dryland forests, and can guide restoration actions by avoiding unsuitable areas for tree establishment in a drier world.
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Affiliation(s)
- Emilio Guirado
- Instituto Multidisciplinar para el Estudio del Medio 'Ramón Margalef', Universidad de Alicante, Alicante, Spain.
| | - Manuel Delgado-Baquerizo
- Laboratorio de Biodiversidad y Funcionamiento Ecosistémico, Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS), CSIC, Sevilla, Spain
- Unidad Asociada CSIC-UPO (BioFun), Universidad Pablo de Olavide, Sevilla, Spain
| | - Jaime Martínez-Valderrama
- Instituto Multidisciplinar para el Estudio del Medio 'Ramón Margalef', Universidad de Alicante, Alicante, Spain
| | - Siham Tabik
- Department of Computer Science and Artificial Intelligence, Andalusian Research Institute in Data Science and Computational Intelligence (DaSCI), University of Granada, Granada, Spain
| | - Domingo Alcaraz-Segura
- iecolab. Inter-University Institute for Earth System Research, University of Granada, Granada, Spain
- Department of Botany, Faculty of Science, University of Granada, Granada, Spain
- Andalusian Center for the Assessment and Monitoring of Global Change -CAESCG-, University of Almeria, Almeria, Spain
| | - Fernando T Maestre
- Instituto Multidisciplinar para el Estudio del Medio 'Ramón Margalef', Universidad de Alicante, Alicante, Spain
- Departamento de Ecología, Universidad de Alicante, Alicante, Spain
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2
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García-montero LG, Pascual C, Martín-fernández S, Sanchez-paus Díaz A, Patriarca C, Martín-ortega P, Mollicone D. Medium- (MR) and Very-High-Resolution (VHR) Image Integration through Collect Earth for Monitoring Forests and Land-Use Changes: Global Forest Survey (GFS) in the Temperate FAO Ecozone in Europe (2000–2015). Remote Sensing 2021; 13:4344. [DOI: 10.3390/rs13214344] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Monitoring of land use, land-use changes, and forestry (LULUCF) plays a crucial role in biodiversity and global environmental challenges. In 2015, the Food and Agriculture Organization of the United Nations (FAO) launched the Global Forest Survey (GFS) integrating medium- (MR) and very-high-resolution (VHR) images through the FAO’s Collect Earth platform. More than 11,150 plots were inventoried in the Temperate FAO ecozone in Europe to monitor LULUCF from 2000 to 2015. As a result, 2.19% (VHR) to 2.77% (MR/VHR) of the study area underwent LULUCF, including a 0.37% (VHR) to 0.43% (MR/VHR) net increase in forest lands. Collect Earth and VHR images have also (i) allowed for shaping a preliminary structure of the land-use network, showing that cropland was the land type that changed most and that cropland and grassland were the more frequent land uses that generated new forest land, (ii) shown that, in 2015, mixed and monospecific forests represented 44.3% and 46.5% of the forest land, respectively, unlike other forest sources, and (iii) shown that 14.9% of the area had been affected by disturbances, particularly wood harvesting (67.47% of the disturbed forests). According to other authors, the area showed a strong correlation between canopy mortality and reported wood removals due to the transition from past clear-cut systems to “close-to-nature” silviculture.
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3
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Guirado E, Blanco-Sacristán J, Rodríguez-Caballero E, Tabik S, Alcaraz-Segura D, Martínez-Valderrama J, Cabello J. Mask R-CNN and OBIA Fusion Improves the Segmentation of Scattered Vegetation in Very High-Resolution Optical Sensors. Sensors (Basel) 2021; 21:E320. [PMID: 33466513 PMCID: PMC7796453 DOI: 10.3390/s21010320] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 12/29/2020] [Accepted: 01/01/2021] [Indexed: 11/17/2022]
Abstract
Vegetation generally appears scattered in drylands. Its structure, composition and spatial patterns are key controls of biotic interactions, water, and nutrient cycles. Applying segmentation methods to very high-resolution images for monitoring changes in vegetation cover can provide relevant information for dryland conservation ecology. For this reason, improving segmentation methods and understanding the effect of spatial resolution on segmentation results is key to improve dryland vegetation monitoring. We explored and analyzed the accuracy of Object-Based Image Analysis (OBIA) and Mask Region-based Convolutional Neural Networks (Mask R-CNN) and the fusion of both methods in the segmentation of scattered vegetation in a dryland ecosystem. As a case study, we mapped Ziziphus lotus, the dominant shrub of a habitat of conservation priority in one of the driest areas of Europe. Our results show for the first time that the fusion of the results from OBIA and Mask R-CNN increases the accuracy of the segmentation of scattered shrubs up to 25% compared to both methods separately. Hence, by fusing OBIA and Mask R-CNNs on very high-resolution images, the improved segmentation accuracy of vegetation mapping would lead to more precise and sensitive monitoring of changes in biodiversity and ecosystem services in drylands.
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Affiliation(s)
- Emilio Guirado
- Multidisciplinary Institute for Environment Studies “Ramon Margalef” University of Alicante, Edificio Nuevos Institutos, Carretera de San Vicente del Raspeig s/n San Vicente del Raspeig, 03690 Alicante, Spain;
- Andalusian Center for Assessment and monitoring of global change (CAESCG), University of Almeria, 04120 Almeria, Spain;
| | - Javier Blanco-Sacristán
- College of Engineering, Mathematics and Physical Sciences, University of Exeter, Penryn Campus, Cornwall TR10 9EZ, UK;
| | - Emilio Rodríguez-Caballero
- Agronomy Department, University of Almeria, 04120 Almeria, Spain;
- Centro de Investigación de Colecciones Científicas de la Universidad de Almería (CECOUAL), 04120 Almeria, Spain
| | - Siham Tabik
- Department of Computer Science and Artificial Intelligence, University of Granada, 18071 Granada, Spain;
| | - Domingo Alcaraz-Segura
- Department of Botany, Faculty of Science, University of Granada, 18071 Granada, Spain;
- iEcolab, Inter-University Institute for Earth System Research, University of Granada, 18006 Granada, Spain
| | - Jaime Martínez-Valderrama
- Multidisciplinary Institute for Environment Studies “Ramon Margalef” University of Alicante, Edificio Nuevos Institutos, Carretera de San Vicente del Raspeig s/n San Vicente del Raspeig, 03690 Alicante, Spain;
| | - Javier Cabello
- Andalusian Center for Assessment and monitoring of global change (CAESCG), University of Almeria, 04120 Almeria, Spain;
- Department of Biology and Geology, University of Almeria, 04120 Almeria, Spain
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4
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Brandt M, Tucker CJ, Kariryaa A, Rasmussen K, Abel C, Small J, Chave J, Rasmussen LV, Hiernaux P, Diouf AA, Kergoat L, Mertz O, Igel C, Gieseke F, Schöning J, Li S, Melocik K, Meyer J, Sinno S, Romero E, Glennie E, Montagu A, Dendoncker M, Fensholt R. An unexpectedly large count of trees in the West African Sahara and Sahel. Nature 2020; 587:78-82. [PMID: 33057199 DOI: 10.1038/s41586-020-2824-5] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 09/09/2020] [Indexed: 11/09/2022]
Abstract
A large proportion of dryland trees and shrubs (hereafter referred to collectively as trees) grow in isolation, without canopy closure. These non-forest trees have a crucial role in biodiversity, and provide ecosystem services such as carbon storage, food resources and shelter for humans and animals1,2. However, most public interest relating to trees is devoted to forests, and trees outside of forests are not well-documented3. Here we map the crown size of each tree more than 3 m2 in size over a land area that spans 1.3 million km2 in the West African Sahara, Sahel and sub-humid zone, using submetre-resolution satellite imagery and deep learning4. We detected over 1.8 billion individual trees (13.4 trees per hectare), with a median crown size of 12 m2, along a rainfall gradient from 0 to 1,000 mm per year. The canopy cover increases from 0.1% (0.7 trees per hectare) in hyper-arid areas, through 1.6% (9.9 trees per hectare) in arid and 5.6% (30.1 trees per hectare) in semi-arid zones, to 13.3% (47 trees per hectare) in sub-humid areas. Although the overall canopy cover is low, the relatively high density of isolated trees challenges prevailing narratives about dryland desertification5-7, and even the desert shows a surprisingly high tree density. Our assessment suggests a way to monitor trees outside of forests globally, and to explore their role in mitigating degradation, climate change and poverty.
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Affiliation(s)
- Martin Brandt
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark. .,Science Systems and Applications Inc., NASA Goddard Space Flight Center, Greenbelt, MD, USA.
| | | | - Ankit Kariryaa
- Science Systems and Applications Inc., NASA Goddard Space Flight Center, Greenbelt, MD, USA.,HCI Group, University of Bremen, Bremen, Germany
| | - Kjeld Rasmussen
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
| | - Christin Abel
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
| | - Jennifer Small
- Science Systems and Applications Inc., NASA Goddard Space Flight Center, Greenbelt, MD, USA.,NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - Jerome Chave
- Laboratoire Evolution and Diversité Biologique, CNRS, UPS, IRD, Université Paul Sabatier, Toulouse, France
| | - Laura Vang Rasmussen
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
| | - Pierre Hiernaux
- Science Systems and Applications Inc., NASA Goddard Space Flight Center, Greenbelt, MD, USA.,Pastoralisme Conseil, Caylus, France
| | | | - Laurent Kergoat
- Geosciences Environnement Toulouse (GET), Observatoire Midi-Pyrénées, UMR 5563 (CNRS/UPS/IRD/CNES), Toulouse, France
| | - Ole Mertz
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
| | - Christian Igel
- Department of Computer Science (DIKU), University of Copenhagen, Copenhagen, Denmark
| | - Fabian Gieseke
- Department of Computer Science (DIKU), University of Copenhagen, Copenhagen, Denmark.,Department of Information Systems, University of Műnster, Műnster, Germany
| | | | - Sizhuo Li
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
| | - Katherine Melocik
- Science Systems and Applications Inc., NASA Goddard Space Flight Center, Greenbelt, MD, USA.,NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - Jesse Meyer
- Science Systems and Applications Inc., NASA Goddard Space Flight Center, Greenbelt, MD, USA.,NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - Scott Sinno
- Science Systems and Applications Inc., NASA Goddard Space Flight Center, Greenbelt, MD, USA.,NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - Eric Romero
- Science Systems and Applications Inc., NASA Goddard Space Flight Center, Greenbelt, MD, USA.,NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - Erin Glennie
- Science Systems and Applications Inc., NASA Goddard Space Flight Center, Greenbelt, MD, USA.,NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - Amandine Montagu
- Département de Géosciences, Ecole Normale Supérieure, Paris, France
| | - Morgane Dendoncker
- Earth and Life Institute, Environmental Sciences, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Rasmus Fensholt
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
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5
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Fagan ME. A lesson unlearned? Underestimating tree cover in drylands biases global restoration maps. Glob Chang Biol 2020; 26:4679-4690. [PMID: 32614489 DOI: 10.1111/gcb.15187] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 04/02/2020] [Indexed: 06/11/2023]
Abstract
Two recent global maps of tree restoration potential have identified vast regions where tree cover could be increased, ranging from 0.9 to 2.3 billion hectares. Both maps, however, emphasized dryland regions, with arid biomes making up 36%-42% of potential restoration area. Dryland biomes have repeatedly been recognized as inappropriate regions for expanding tree cover due to the risks of biodiversity loss, water overconsumption, and fire, so maps that highlight these regions for restoration must sustain careful scrutiny. Here, I show that both recent attempts to map restoration potential in arid regions have been hindered by underlying errors in the global tree cover maps they used. Systematic underestimates of existing sparse tree cover led directly to large overestimates of the potential for tree recovery in drylands. The Atlas of Forest Landscape Restoration Opportunities (Laestadius et al., Unasylva, 2011, 62, 47) overestimated tree restoration potential across a third of arid biomes by between 7% and 20% (55-166 million hectares [Mha]). Similarly, Bastin, Finegold, Garcia, Mollicone, et al. (Science, 2019, 365, 76) overestimated tree restoration potential across all arid biomes by 33%-45% (316-440 Mha). These inaccuracies limit the utility of this research for policy decisions in drylands and overstate the potential for tree planting to address climate change. Given this long-standing but underappreciated challenge in mapping global tree cover, I propose various ways forward that keep this lesson in mind. To better monitor and restore tree cover, I call for re-interpretation and correction of existing global maps, and for a new focus on quantifying sparse tree cover in drylands and other systems.
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Affiliation(s)
- M E Fagan
- Department of Geography and Environmental Systems, University of Maryland Baltimore County, Baltimore, MD, USA
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6
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Sparrow BD, Foulkes JN, Wardle GM, Leitch EJ, Caddy-Retalic S, van Leeuwen SJ, Tokmakoff A, Thurgate NY, Guerin GR, Lowe AJ. A Vegetation and Soil Survey Method for Surveillance Monitoring of Rangeland Environments. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.00157] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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7
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Guirado E, Alcaraz-segura D, Cabello J, Puertas-ruíz S, Herrera F, Tabik S. Tree Cover Estimation in Global Drylands from Space Using Deep Learning. Remote Sensing 2020; 12:343. [DOI: 10.3390/rs12030343] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Accurate tree cover mapping is of paramount importance in many fields, from biodiversity conservation to carbon stock estimation, ecohydrology, erosion control, or Earth system modelling. Despite this importance, there is still uncertainty about global forest cover, particularly in drylands. Recently, the Food and Agriculture Organization of the United Nations (FAO) conducted a costly global assessment of dryland forest cover through the visual interpretation of orthoimages using the Collect Earth software, involving hundreds of operators from around the world. Our study proposes a new automatic method for estimating tree cover using artificial intelligence and free orthoimages. Our results show that our tree cover classification model, based on convolutional neural networks (CNN), is 23% more accurate than the manual visual interpretation used by FAO, reaching up to 79% overall accuracy. The smallest differences between the two methods occurred in the driest regions, but disagreement increased with the percentage of tree cover. The application of CNNs could be used to improve and reduce the cost of tree cover maps from the local to the global scale, with broad implications for research and management.
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8
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Lesiv M, See L, Laso Bayas J, Sturn T, Schepaschenko D, Karner M, Moorthy I, Mccallum I, Fritz S. Characterizing the Spatial and Temporal Availability of Very High Resolution Satellite Imagery in Google Earth and Microsoft Bing Maps as a Source of Reference Data. Land 2018; 7:118. [DOI: 10.3390/land7040118] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Very high resolution (VHR) satellite imagery from Google Earth and Microsoft Bing Maps is increasingly being used in a variety of applications from computer sciences to arts and humanities. In the field of remote sensing, one use of this imagery is to create reference data sets through visual interpretation, e.g., to complement existing training data or to aid in the validation of land-cover products. Through new applications such as Collect Earth, this imagery is also being used for monitoring purposes in the form of statistical surveys obtained through visual interpretation. However, little is known about where VHR satellite imagery exists globally or the dates of the imagery. Here we present a global overview of the spatial and temporal distribution of VHR satellite imagery in Google Earth and Microsoft Bing Maps. The results show an uneven availability globally, with biases in certain areas such as the USA, Europe and India, and with clear discontinuities at political borders. We also show that the availability of VHR imagery is currently not adequate for monitoring protected areas and deforestation, but is better suited for monitoring changes in cropland or urban areas using visual interpretation.
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Symeonakis E, Higginbottom T, Petroulaki K, Rabe A. Optimisation of Savannah Land Cover Characterisation with Optical and SAR Data. Remote Sensing 2018; 10:499. [DOI: 10.3390/rs10040499] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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10
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Guirado E, Tabik S, Alcaraz-segura D, Cabello J, Herrera F. Deep-learning Versus OBIA for Scattered Shrub Detection with Google Earth Imagery: Ziziphus lotus as Case Study. Remote Sensing 2017; 9:1220. [DOI: 10.3390/rs9121220] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Bastin JF, Mollicone D, Grainger A, Sparrow B, Picard N, Lowe A, Castro R. Response to Comment on "The extent of forest in dryland biomes". Science 2017; 358:358/6364/eaao2077. [PMID: 29123036 DOI: 10.1126/science.aao2077] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 08/15/2017] [Indexed: 11/02/2022]
Abstract
De la Cruz et al question the reliability of our results, claiming that we do not refer to the most appropriate spatial extent of drylands. In our response, we explain why we chose an existing and internationally recognized delineation of drylands among several options, and why our findings are due to a difference of remote sensing technique and not to the definition of drylands we have selected.
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Affiliation(s)
- J-F Bastin
- Food and Agriculture Organization of the United Nations, Vialle delle Terme di Caracalla, 00153 Rome, Italy.,Landscape Ecology and Plant Production Systems Unit, Université libre de Bruxelles, CP264-2, B-1050 Bruxelles, Belgium
| | - D Mollicone
- Food and Agriculture Organization of the United Nations, Vialle delle Terme di Caracalla, 00153 Rome, Italy
| | - A Grainger
- School of Geography, University of Leeds, Leeds LS2 9JT, UK
| | - B Sparrow
- Terrestrial Ecosystem Research Network, School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - N Picard
- Food and Agriculture Organization of the United Nations, Vialle delle Terme di Caracalla, 00153 Rome, Italy
| | - A Lowe
- Terrestrial Ecosystem Research Network, School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - R Castro
- Food and Agriculture Organization of the United Nations, Vialle delle Terme di Caracalla, 00153 Rome, Italy
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12
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Bastin JF, Mollicone D, Grainger A, Sparrow B, Picard N, Lowe A, Castro R. Response to Comment on "The extent of forest in dryland biomes". Science 2017; 358:358/6362/eaao2070. [PMID: 29074741 DOI: 10.1126/science.aao2070] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 08/15/2017] [Indexed: 11/02/2022]
Abstract
Schepaschenko et al question our findings, claiming that we did not refer to all existing maps and that we did not account for all sources of uncertainty. In our response, we detail our selection criteria for reference maps, which clarify why the work of Schepaschenko et al was not used, and we explain why our uncertainty assessment is complete and how it was misunderstood by Schepaschenko et al.
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Affiliation(s)
- J-F Bastin
- Food and Agriculture Organization of the United Nations, Vialle delle Terme di Caracalla, 00153 Rome, Italy.,Landscape Ecology and Plant Production Systems Unit, Université libre de Bruxelles, CP264-2, B-1050 Bruxelles, Belgium
| | - D Mollicone
- Food and Agriculture Organization of the United Nations, Vialle delle Terme di Caracalla, 00153 Rome, Italy
| | - A Grainger
- School of Geography, University of Leeds, Leeds LS2 9JT, UK
| | - B Sparrow
- Terrestrial Ecosystem Research Network, School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - N Picard
- Food and Agriculture Organization of the United Nations, Vialle delle Terme di Caracalla, 00153 Rome, Italy
| | - A Lowe
- Terrestrial Ecosystem Research Network, School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - R Castro
- Food and Agriculture Organization of the United Nations, Vialle delle Terme di Caracalla, 00153 Rome, Italy
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