Land cover change and carbon emissions over 100 years in an African biodiversity hotspot

Simon Willcock; Oliver L Phillips; Philip J Platts; Ruth D Swetnam; Andrew Balmford; Neil D Burgess; Antje Ahrends; Julian Bayliss; Nike Doggart; Kathryn Doody; Eibleis Fanning; Jonathan M H Green; Jaclyn Hall; Kim L Howell; Jon C Lovett; Rob Marchant; Andrew R Marshall; Boniface Mbilinyi; Pantaleon K T Munishi; Nisha Owen; Elmer J Topp-Jorgensen; Simon L Lewis

doi:10.1111/gcb.13218

Land cover change and carbon emissions over 100 years in an African biodiversity hotspot

Glob Chang Biol. 2016 Aug;22(8):2787-800. doi: 10.1111/gcb.13218. Epub 2016 May 9.

Authors

Simon Willcock^{1

2}, Oliver L Phillips¹, Philip J Platts³, Ruth D Swetnam⁴, Andrew Balmford⁵, Neil D Burgess^{6

7}, Antje Ahrends⁸, Julian Bayliss⁹, Nike Doggart¹⁰, Kathryn Doody¹¹, Eibleis Fanning¹², Jonathan M H Green¹³, Jaclyn Hall¹⁴, Kim L Howell¹⁵, Jon C Lovett¹, Rob Marchant¹⁶, Andrew R Marshall^{16

17}, Boniface Mbilinyi¹⁸, Pantaleon K T Munishi¹⁸, Nisha Owen^{12

19}, Elmer J Topp-Jorgensen²⁰, Simon L Lewis^{1

21}

Affiliations

¹ School of Geography, University of Leeds, Leeds, LS2 9JT, UK.
² Centre for Biological Sciences, University of Southampton, Southampton, SO17 1BJ, UK.
³ Department of Biology, University of York, York, YO10 5DD, UK.
⁴ Department of Geography, Staffordshire University, Stoke-on-Trent, ST4 2DF, UK.
⁵ Department of Zoology, University of Cambridge, Cambridge, CB2 3EJ, UK.
⁶ Center of Macroecology, Evolution and Climate, Copenhagen, DK-2100, Denmark.
⁷ UNEP World Conservation Monitoring Centre, Cambridge, CB3 0DL, UK.
⁸ Genetics and Conservation, Royal Botantic Garden Edinburgh, Edinburgh, EH3 5LR, UK.
⁹ Department of Biological & Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK.
¹⁰ Tanzanian Forest Conservation Group, PO Box 23410, Dar es Salaam, Tanzania.
¹¹ Frankfurt Zoological Society, Frankfurt, D-60316, Germany.
¹² The Society for Environmental Exploration, London, EC2A 3QP, UK.
¹³ STEP Program, Princeton University, Princeton, NJ, 08544, USA.
¹⁴ Department of Geography, University of Florida, PO Box 117315, Gainesville, FL, 32611, USA.
¹⁵ The University of Dar es Salaam, PO Box 35091, Dar es Salaam, Tanzania.
¹⁶ Environment Department, University of York, York, YO10 5DD, UK.
¹⁷ Centre for the Integration of Research, Conservation and Learning, Flamingo Land Ltd., Malton, YO 17 6UX, UK.
¹⁸ Sokoine University of Agriculture, PO Box 3001, Morogoro, Tanzania.
¹⁹ EDGE of Existence, Conservation Programmes, Zoological Society of London, London, NW1 4RY, UK.
²⁰ Department of Bioscience, Aarhus University, DK-8000, Aarhus C, Denmark.
²¹ Department of Geography, University College London, London, WC1E 6BT, UK.

PMID: 26748590
DOI: 10.1111/gcb.13218

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.

Keywords: afforestation; carbon; deforestation; ecosystem service; emission; land use change; protected area; reforestation.

MeSH terms

Agriculture
Biodiversity*
Carbon / adverse effects
Carbon / analysis*
Conservation of Natural Resources*
Forests

Substances

Carbon