title: Land cover change and carbon emissions over 100 years in an African biodiversity hotspot.
abstract: Agricultural expansion has resulted in both land use and land cover change (LULCC) across the tropics. However, the spatial and temporal patterns of such change and their resulting impacts are poorly understood, particularly for the presatellite era. Here, we quantify the LULCC history across the 33.9 million ha watershed of Tanzania's Eastern Arc Mountains, using geo-referenced and digitized historical land cover maps (dated 1908, 1923, 1949 and 2000). Our time series from this biodiversity hotspot shows that forest and savanna area both declined, by 74% (2.8 million ha) and 10% (2.9 million ha), respectively, between 1908 and 2000. This vegetation was replaced by a fivefold increase in cropland, from 1.2 million ha to 6.7 million ha. This LULCC implies a committed release of 0.9 Pg C (95% CI: 0.4-1.5) across the watershed for the same period, equivalent to 0.3 Mg C ha(-1)  yr(-1) . This is at least threefold higher than previous estimates from global models for the same study area. We then used the LULCC data from before and after protected area creation, as well as from areas where no protection was established, to analyse the effectiveness of legal protection on land cover change despite the underlying spatial variation in protected areas. We found that, between 1949 and 2000, forest expanded within legally protected areas, resulting in carbon uptake of 4.8 (3.8-5.7) Mg C ha(-1) , compared to a committed loss of 11.9 (7.2-16.6) Mg C ha(-1) within areas lacking such protection. Furthermore, for nine protected areas where LULCC data are available prior to and following establishment, we show that protection reduces deforestation rates by 150% relative to unprotected portions of the watershed. Our results highlight that considerable LULCC occurred prior to the satellite era, thus other data sources are required to better understand long-term land cover trends in the tropics.
authors.affiliation: School of Geography, University of Leeds, Leeds, LS2 9JT, UK.|Centre for Biological Sciences, University of Southampton, Southampton, SO17 1BJ, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Willcock
authors.affiliation: School of Geography, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: Oliver L
authors.initials: OL
authors.lastname: Phillips
authors.affiliation: Department of Biology, University of York, York, YO10 5DD, UK.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Platts
authors.affiliation: Department of Geography, Staffordshire University, Stoke-on-Trent, ST4 2DF, UK.
authors.forename: Ruth D
authors.initials: RD
authors.lastname: Swetnam
authors.affiliation: Department of Zoology, University of Cambridge, Cambridge, CB2 3EJ, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Balmford
authors.affiliation: Center of Macroecology, Evolution and Climate, Copenhagen, DK-2100, Denmark.|UNEP World Conservation Monitoring Centre, Cambridge, CB3 0DL, UK.
authors.forename: Neil D
authors.initials: ND
authors.lastname: Burgess
authors.affiliation: Genetics and Conservation, Royal Botantic Garden Edinburgh, Edinburgh, EH3 5LR, UK.
authors.forename: Antje
authors.initials: A
authors.lastname: Ahrends
authors.affiliation: Department of Biological & Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK.
authors.forename: Julian
authors.initials: J
authors.lastname: Bayliss
authors.affiliation: Tanzanian Forest Conservation Group, PO Box 23410, Dar es Salaam, Tanzania.
authors.forename: Nike
authors.initials: N
authors.lastname: Doggart
authors.affiliation: Frankfurt Zoological Society, Frankfurt, D-60316, Germany.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Doody
authors.affiliation: The Society for Environmental Exploration, London, EC2A 3QP, UK.
authors.forename: Eibleis
authors.initials: E
authors.lastname: Fanning
authors.affiliation: STEP Program, Princeton University, Princeton, NJ, 08544, USA.
authors.forename: Jonathan M H
authors.initials: JM
authors.lastname: Green
authors.affiliation: Department of Geography, University of Florida, PO Box 117315, Gainesville, FL, 32611, USA.
authors.forename: Jaclyn
authors.initials: J
authors.lastname: Hall
authors.affiliation: The University of Dar es Salaam, PO Box 35091, Dar es Salaam, Tanzania.
authors.forename: Kim L
authors.initials: KL
authors.lastname: Howell
authors.affiliation: School of Geography, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: Jon C
authors.initials: JC
authors.lastname: Lovett
authors.affiliation: Environment Department, University of York, York, YO10 5DD, UK.
authors.forename: Rob
authors.initials: R
authors.lastname: Marchant
authors.affiliation: Environment Department, University of York, York, YO10 5DD, UK.|Centre for the Integration of Research, Conservation and Learning, Flamingo Land Ltd., Malton, YO 17 6UX, UK.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Marshall
authors.affiliation: Sokoine University of Agriculture, PO Box 3001, Morogoro, Tanzania.
authors.forename: Boniface
authors.initials: B
authors.lastname: Mbilinyi
authors.affiliation: Sokoine University of Agriculture, PO Box 3001, Morogoro, Tanzania.
authors.forename: Pantaleon K T
authors.initials: PK
authors.lastname: Munishi
authors.affiliation: The Society for Environmental Exploration, London, EC2A 3QP, UK.|EDGE of Existence, Conservation Programmes, Zoological Society of London, London, NW1 4RY, UK.
authors.forename: Nisha
authors.initials: N
authors.lastname: Owen
authors.affiliation: Department of Bioscience, Aarhus University, DK-8000, Aarhus C, Denmark.
authors.forename: Elmer J
authors.initials: EJ
authors.lastname: Topp-Jorgensen
authors.affiliation: School of Geography, University of Leeds, Leeds, LS2 9JT, UK.|Department of Geography, University College London, London, WC1E 6BT, UK.
authors.forename: Simon L
authors.initials: SL
authors.lastname: Lewis
mesh_terms: D000383:Agriculture; D044822:Biodiversity; D002244:Carbon / Q000009:adverse effects / Q000032:analysis*; D003247:Conservation of Natural Resources; D065928:Forests
chemical_list: D002244:Carbon
keywords: afforestation; carbon; deforestation; ecosystem service; emission; land use change; protected area; reforestation