Mangrove trends, threats & opportunities

VTB Studiedag ‘: Living on the edge’ Burgers Zoo, Arnhem, 15 September 2017 Wim Giesen Outline of presentation

1. Introduction to mangroves 2. World-wide status & trends 3. Threats to mangroves 4. Opportunities for sustainable management Introduction to mangroves

What are mangroves?

▪ Trees or shrubs found in intertidal (saline) environments in tropics & subtropics ▪ Dwarf shrubs or trees up to 30(-40) m tall ▪ ‘’ used describe individual or assemblages of plants (including herbs, climbers, etc...) ▪ Zonation: exposed, central, rear mangroves Introduction to mangroves

Source: UNEP (2013) Introduction to mangroves Ecological niche

▪ occupy interface of land and sea ▪ tolerant of saline conditions & low oxygen levels (of ‘soil’) ▪ common adaptations include aerial roots, viviparous embryos, water dispersal of propagules, salt-tolerance (or disposal) ▪ distinction: exclusive (‘true mangrove’) & non-exclusive (‘associate’) ▪ exclusive: 70+ species world-wide (60-84) ▪ richest mangroves are in SE Asia: 52 exclusive, >220 associate species Introduction to mangroves Mangrove uses

▪ highly productive (almost 50% more than tropical lowland forests) ▪ 77% SE Asian mangrove species have use (medicine, food, fodder, fuel & timber) • NPP mangroves: 14.7 MgC ha-1 yr-1 (range 4-26.7) (Komiyama et al. 2008) ▪ support coastal fisheries & biodiversity -1 -1 ▪ buffers• NPPwavelowland action/coastal rainforests: protection 10 MgC (storms,ha yr tsunamis),(7.3-12.8) sediment (Malhi 2012) stabilisation ▪ improve coastal water quality by retention, removal & cycling nutrients, pollutants & particulate matter from land-based sources World-wide status & trends

Top 15 mangrove countries

Philippines Area & distribution Madagascar Mozambique Guinea Bissau India Cuba ▪ world-wide ±138,000 km² (2000), in Bangladesh 124 (sub-)tropical countries Papua New Guinea Myanmar ▪ >75% in just 15 countries Nigeria ▪ : about 25% of global total Mexico Brazil Australia ▪ Belize: 74,684 ha or 0.57% Indonesia 0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 km2 (Giri et al. 2011) World-wide status & trends

Mangrove area (km2) 250,000 Changes in area 200,000

▪ 1980-2000: decline by almost one 150,000 third (FAO 2007: 26%; Giri et al. 2011: 35%) 100,000 ▪ Since 2000: continued decline (albeit slowing down in most areas) 50,000

0 1975 1980 1985 1990 1995 2000 2005 2010 2015 World-wide status & trends

4,500,0009000 Africa 2,7 9 4,000,0008000 1 Asia 1. Giesen (1993) 5 America 2. Bina Program (1982) 7000 3. Silvius et al. (1987) 3,500,000 7 Regional differences 7 Oceania 4. NEDECO (1984) 3 11 5. RePPProT (1985) 3,000,0006000 6. BAPLAN (2006) 7. FAO (2003) 7 10 6 8. Spalding et al. (1997) 2,500,0005000 9. WCMC (1987) ▪ Declines highest in Asia, lowest in 1 8 10. BAPLAN (2010) 11. PSSDAL (2009) 4 Oceania 2,000,0004000

▪ Indonesia follows this trend: 33% 1,500,000(km2) area Mangrove 3000 decline from 1970-2010 (Giesen et al. 2013) (ha) area Mangrove 1,000,0002000 ▪ Belize: 4% decline 1980-2010 500,0001000

0 1970 1980 1980 19901990 20002000 20102005

World-wide: 1980-90: -1.04% decline 1990-00: -0.72% 2000-06: -0.66%

2010-16: -0.3% (Giri et al. 2011, Hamilton & Casey 2016)

SE Asia: 2000-2012 -2.12% decline (Richard & Friess 2016) World-wide status & trends

In-country differences: Indonesia

▪ >90% loss in South Sulawesi, West & East Java ▪ <10% loss in Papua

(Giesen et al. 2013) World-wide status & trends Impact on biodiversity

Family Species IUCN Distribution bicolor VU Eastern Tropical Pacific from Mexico to Colombia. Acanthaceae Avicennia integra VU Endemic to northern Australia, found in only 15 locations. Acanthaceae Avicennia rumphiana VU Indonesia; Malaysia; Papua New Guinea; Philippines Bignoniaceae Tabebuia palustris VU Pacific coast of Costa Rica, Panama, and Colombia Note: these are exclusive mangroveEast Pacific: trees Costaonly Rica,& does Panama, Colombia and northern Fabaeae notMorainclude oleifera associate speciesVU (includingEcuador. trees, but also climbers, epiphytes, etc...) Very local and rare: Bangladesh, India, Indonesia, Malaysia, Lythraceae Sonneratia griffithii CR Myanmar, Thailand Patchily distributed in Indonesia (Borneo and Sulawesi), and Malvaceae Camptostemon philippensis EN the Philippines. India, Bangladesh, (Irrawaddy) Myanmar, Thailand, and Malvaceae Heritiera fomes EN northern Malaysia This species is endemic to Borneo (West Kalimantan, Malvaceae Heritiera globosa EN Indonesia). Very limited patchy distribution: Indonesia, Malaysia, Thailand, Rhizophoraceae Bruguiera hainesii CR Myanmar, Philippines, Papua New Guinea & Singapore. Source: Polidoro et al. (2010) Threats to mangroves

Multiple threats

• Logging • Conversion • Violent storms • Pollution • Lack of freshwater input • Smothering by sediments • Disease Threats to mangroves

Impacts of climate change

• Sea level rise: loss of area (>30%?), landward migration • Air temperature increase (2-4°C in next 100 years): latitudinal expansion • Increase / more intense storms: damage & loss • Precipitation changes: increases/decreases • Species composition changes (due to different responses) (Finlayson 2016) Threats to mangroves Drivers of mangrove conversion Drivers of change Southeast Asia

aquaculture 12% 2/3’s of loss = due to conversion to 4% 30% rice oil palm aquaculture ponds, rice fields & 16% oil palm plantation regrowth urban 16% 22% other Richards & Friess (2016) - Rates and drivers of mangrove deforestation in Southeast Asia, 2000–2012. PNAS vol. 113 (2): 344-349 Threats to mangroves Indonesian mangroves Assessment of Indonesian mangroves (2013) Primary mangroves 2% 15% Secondary mangroves • original area: 4 Mha 32% • declined to 2.7 Mha by 2010 14% degraded habitats (non-forest)

• fishponds (tambak) = 636,000 ha fish-ponds • rest = mainly degraded (non-forest) 37% habitat other land use (Giesen et al. 2013) Opportunities

▪ Responsible aquaculture & certification (presentation Roel Bosma) ▪ 2004 tsunami & climate change: need for coastal protection (presentation Pieter van Eijk on mangrove recovery) ▪ CC & carbon emissions: blue carbon (presentation Boone Kauffman) ▪ Fisheries, NTFPs, ecotourism & other benefits (presentation Daniel Knoop on local economic benefits) Thank you for your attention

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