title: Quantifying and understanding carbon storage and sequestration within the Eastern Arc Mountains of Tanzania, a tropical biodiversity hotspot.
abstract: BACKGROUND
  The carbon stored in vegetation varies across tropical landscapes due to a complex mix of climatic and edaphic variables, as well as direct human interventions such as deforestation and forest degradation. Mapping and monitoring this variation is essential if policy developments such as REDD+ (Reducing Emissions from Deforestation and Forest Degradation) are to be known to have succeeded or failed.
  
  
  RESULTS
  We produce a map of carbon storage across the watershed of the Tanzanian Eastern Arc Mountains (33.9 million ha) using 1,611 forest inventory plots, and correlations with associated climate, soil and disturbance data. As expected, tropical forest stores more carbon per hectare (182 Mg C ha(-1)) than woody savanna (51 Mg C ha(-1)). However, woody savanna is the largest aggregate carbon store, with 0.49 Pg C over 9.6 million ha. We estimate the whole landscape stores 1.3 Pg C, significantly higher than most previous estimates for the region. The 95% Confidence Interval for this method (0.9 to 3.2 Pg C) is larger than simpler look-up table methods (1.5 to 1.6 Pg C), suggesting simpler methods may underestimate uncertainty. Using a small number of inventory plots with two censuses (n = 43) to assess changes in carbon storage, and applying the same mapping procedures, we found that carbon storage in the tree-dominated ecosystems has decreased, though not significantly, at a mean rate of 1.47 Mg C ha(-1) yr(-1) (c. 2% of the stocks of carbon per year).
  
  
  CONCLUSIONS
  The most influential variables on carbon storage in the region are anthropogenic, particularly historical logging, as noted by the largest coefficient of explanatory variable on the response variable. Of the non-anthropogenic factors, a negative correlation with air temperature and a positive correlation with water availability dominate, having smaller p-values than historical logging but also smaller influence. High carbon storage is typically found far from the commercial capital, in locations with a low monthly temperature range, without a strong dry season, and in areas that have not suffered from historical logging. The results imply that policy interventions could retain carbon stored in vegetation and likely successfully slow or reverse carbon emissions.
authors.affiliation: School of Geography, University of Leeds, Leeds LS2 9JT, UK ; School of 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: Environment Department, University of York, York YO10 5DD, UK.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Platts
authors.affiliation: Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Balmford
authors.affiliation: WWF US, Washington, USA ; UNEP World Conservation Monitoring Centre, Cambridge CB3 0DL, UK.
authors.forename: Neil D
authors.initials: ND
authors.lastname: Burgess
authors.affiliation: School of Geography, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Jon C
authors.initials: JC
authors.lastname: Lovett
authors.affiliation: Genetics and Conservation, Royal Botantic Garden Edinburgh, Edinburgh, UK.
authors.forename: Antje
authors.initials: A
authors.lastname: Ahrends
authors.affiliation: Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK.
authors.forename: Julian
authors.initials: J
authors.lastname: Bayliss
authors.affiliation: Tanzanian Forest Conservation Group, 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 08544, USA.
authors.forename: Jonathan Mh
authors.initials: JM
authors.lastname: Green
authors.affiliation: Department of Geography, University of Florida, PO Box 117315, Gainesville, Florida, FL 32611, USA.
authors.forename: Jaclyn
authors.initials: J
authors.lastname: Hall
authors.affiliation: The University of Dar es Salaam, Dar es Salaam, Tanzania.
authors.forename: Kim L
authors.initials: KL
authors.lastname: Howell
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 Kt
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, UK.
authors.forename: Nisha
authors.initials: N
authors.lastname: Owen
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 Bioscience, Aarhus University, Aarhus C DK-8000, 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
keywords: Degradation; Disturbance; Eastern Arc Mountains; Ecosystem service; Forest; IPCC Tier 3; REDD+; Tanzania