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A Paradox? Tree Species Diversity and Carbon Storage in Zomba City

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A Paradox? Tree Species Diversity and Carbon Storage in Zomba City
Frank Chimaimba, RCE Zomba
8th African RCE Meeting
8-10 August, 2018, Zomba, Malawi

Published in: Government & Nonprofit
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A Paradox? Tree Species Diversity and Carbon Storage in Zomba City

  1. 1. A PARADOX? TREE SPECIES DIVERSITY AND CARBON STORAGE IN ZOMBA CITY, MALAWI by Frank B. Chimaimba
  2. 2. Acknowledgement  LEAD SEA through AfriCity project (BMBF 01DG16015 / DAAD Project-ID 57353580) funded by DAAD and BMBF 2
  3. 3. A PARADOX? TREE SPECIES DIVERSITY AND CARBON STORAGE IN ZOMBA CITY, MALAWI by Frank B. Chimaimba
  4. 4. Introduction  Traditionally, urban landscapes are associated with: 1. low biodiversity 2. less indigenous vegetation 3. Almost zero carbon storage 4
  5. 5. Introduction cont..  The word “City” = intense infrastructural development, Many cars, High pollution and High population density 5
  6. 6. Introduction cont..  Ecological Studies in support of this assertion  Blair (2001) - few avian species in city centre of Palo Alto, California.  Blood et al (2016) - more exotic tree species in South-eastern US 6
  7. 7. Introduction cont..  Meanwhile, some evidences from literature suggest otherwise.  Colding et al (2013) - Urban forests in Sweden attained rare and endangered species  Kühn et al, (2004) – Both native and exotic tree species were higher in cities. 7
  8. 8. Introduction cont..  Despite global growth of evidences, evidences from Africa are limited.  Ecological Research, policies have paid much less attention on cities  Need for more evidences in African Cities to set the context appropriately. 8
  9. 9. Aims  To establish tree species diversity and Carbon storage of Zomba city, Malawi.  Perhaps to probe ecological scientist, Policy makers etc. 9
  10. 10. Study area  Zomba city (at the foot of Zomba Mountain)  39 km2 area – relatively small  Considerable urban growth  Experiences tropical climate (3 seasons)  Capital of Malawi in 1891- British protectorate  Granted city status in 2008 10
  11. 11. Sampling design  Stratified sampling design by land use types.  Used in UFORE model development in 1990’s  Six Land use types were sampled.  Urban parks, Cemeteries, Institution (Schools, lodges, churches and offices), afforestation hills, roads, and residential areas. 11
  12. 12. Sampling techniques  Were dependant on land use type  Road – Belt transects (Quadrats = 20m length with varied width; regular interval= 500m)  All non linear, except residential and institutions - 10m x 10m (100m2 ) or 20 x 20m (400m2 )  Residential and institution- area measured and all trees within. For Woodlots-100m2 plots were taken 12
  13. 13. Sampling techniques cont.. The following were recorded on each plot  Coordinates – GPS (62sc Garmin)  Tree species  DBH (≥ 5cm)– diameter tape  Height – hypsometer pair 13
  14. 14. Data Analysis  The data was populated in Microsoft Excel  Descriptive analysis (Frequencies, %) – Microsoft excel  Diversity indices - R package.  Shannon Wiener diversity index  Simpson diversity index 14
  15. 15. Data Analysis cont.. Biomass and Carbon stock AGB =0.103685 x dbh1.921719 x ht0.844561 C = TLB x CF 15
  16. 16. Results  The study recorded 2737 tree stems.  With 176 tree species  Chao 1 extrapolated 268 species (92 not observed) High than some forests reserves 16
  17. 17. Results cont.. 17 • This is against the traditional notion
  18. 18. Results cont.. 18
  19. 19. Results cont.. 19
  20. 20. Results cont.. 20
  21. 21. Results cont.. 21
  22. 22. Results cont..  Apart from the two:  Pterocarpus angolensis  Afzelia quansensis  Burkea Africana  Terminalia sericea  A home of 6 protected tree (Forest act, 1997) 22
  23. 23. Results cont.. Number of individual tree count Observed Species Richness Estimated Chao1 Shannon- Wiener Index Simpson index Zomba City 2737 176 268 4.261 0.969 Exotic trees 1572 64 98 3.282 0.923 Indigenous trees 1165 112 170 3.980 0.970 23
  24. 24. Results cont..  This is well backed in literature.  Agbelade et al., (2016) - Mina (3.08) and Abuja (3.56) in Nigeria  Possible reasons of High diversity of native species:  low urbanisation level – intermediate disturbance theory  High regeneration-afforestation initiatives  Botanical garden / parks (Kuhn et al (2016) 24
  25. 25. Results cont..  Above-ground Carbon stock  Zomba city stores a considerable amount of above ground carbon stock of trees.  1136.2 t/ha  Agrees with several studies e.g. Nero (2016) 25
  26. 26. Results cont.. 26
  27. 27. Results cont..  Reasons for this:  Difference in allometric models used.  Perhaps the city has high proportion of large trees 27
  28. 28. Conclusion  The study confirms that  Urban landscapes are unquestionably important embodiment of tree species diversity and carbon storage. Yet are marginalised  Justify the consideration of urban landscapes as viable options for biodiversity conservation and climate mitigation, besides the protected areas  Promotion of this leads to sustainable cities 28
  29. 29. Thank you For Your attention 29

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