Mangrove Forests

1
Mangrove Forests
Dr. James A. Danoff-Burg Columbia University
2
Mangrove Forests

• Found in coastal areas all over the tropics
• Primarily in brackish water
• salty and fresh mix
• Cover approximately 22 million hectares in
  tropical and subtropical coasts

3
Ecosystem Functions Threats

• Serve as an important buffer between sea and land
• Lessen impact of intense storms
• Reduce erosion and increase sedimentation
• Important coastal pioneer species
• Act as basis for a complex, biologically diverse,
  and productive ecosystem
• Increasingly threatened
• Human development is most intense along coasts

4
Mangroves

• Not a natural taxonomic group
• Convergence among several groups
• Possibly 16 convergent events
• Based on physiological attributes
• 54 species total world-wide
• 16 Families
• Principally Avicenniaceae Rhizophoraceae
• These two families include 25 spp.
• 20 Genera

5
Mangrove Location

• Found in tropical areas only
• Within the 20ºC isocline
• More southern on East side of continents
• Due to southward moving warm Equatorial currents
  there

6
Terminology

• Mangal
• Community of organisms in the mangrove habitat
• Mangrove
• Trees that flourish in the mangal
• Pneumatophore
• Vertical root structures for air exchange
• Lenticels - tiny pores for air exchange
• Aerenchyma tissue for air storage

7
Characteristics of Mangal

• Inundation with tides
• Increasing salinity towards ocean
• Sandy clay soil
• Nutrient poor
• Nitrogen Phosphorus are limiting
• Limiting mangrove growth only
• Organic nutrients deposited via siltation
• Fresh water streams down-shore currents
• Most all are of terrestrial origin
• In sum Mangal is a harsh place to live

8
Mangrove Adaptations

• Salt tolerance
• Sequester in tissue (bark, stem, root)
• Secrete through leaves
• Exclusion by negative hydrostatic pressure
• Frequent inundation
• Aerenchyma tissue aerial roots
• Tolerant of soils low in oxygen
• Hypoxic or anoxic

9
Mangrove Consequences of Adaptations

• Greater root mass
• Relative to rest of plant relative to
  non-mangrove species
• For water exchange air exchange
• Lower growth rates
• Consequence of salt air exchange
• Tradeoff between salt tolerance frequent
  inundation
• Can adapt for one or other
• Not both

10
Mangrove Pollination

• Pollination method varies by species
• Wind (Rhizophora)
• bat or hawk moth (Sonneratia)
• birds and butterflies (Bruguiera)
• bees (Acanthus, Aegiceras, Avicennia, Excoecaria,
  Xylocarpus)
• fruit flies (Nypa)
• other small insects (Ceriops, Kandelia)

11
Mangrove Reproduction

• Vivipary normal
• Reproduction and growth while still attached to
  plant
• Flowering
• Fertilization
• Propagule growth

Mature propagule
Young propagule a.k.a. Hypocotyl
12
Mangrove Dispersal

• Maturity -gt Drop off maternal plant
• Float horizontally initially
• Dispersal to novel environments ideally
• Float vertically with appropriate environmental
  conditions
• Rooting and growth

13
Mangal Habitat Types (from inland to oceanfront)

• Riverine
• Often found in river deltas
• Constant influx of freshwater
• Great changes in salinity levels
• Basin Mangroves
• Inland, behind coastal mangroves
• Little change in tides, no wave action
• Often higher salinity than others (evaporation)
• Tide-Dominated
• Coastal front habitats
• Frequent sedimentation
• Unstable morphology due to coastal erosion

14
Intraspecific Differences in Environmental
Tolerances

• Salinity variations and adaptations for excreting
  salt
• Varies within and between species
• Through growth stages
• Tidal Inundation and adaptations for gas exchange
• Pneumatophores and other aerial root extensions
• Low soil stability, Shore morphology, and
  adaptations for rooting
• Prop Roots
• Sedimentation rates and types

15
Mangrove Species Zonation
Ceriops australis
Avicennia marina
16
Most Common Species

• Red Mangrove
• (Rhizophora mangle)
• Black Mangrove
• (Avicennia germinans)
• White Mangrove
• (Laguncularia racemosa)
• All are found throughout tropics

17
Bark Identification
18
Tree Characters
19
Pneumatophores
20
Epiphytes
21
For more information

• Go to http//www.earthisland.org/map/mngec.htm
  and read the ecology link
• A clearinghouse on information on mangrove
  ecology is available at http//www.ncl.ac.uk/tcmwe
  b/tcm/mglinks.htm

22
Mangroves of Australia

• The mangrove plants of Queensland (from
  http//www.aims.gov.au/pages/reflib/fg-mangroves/p
  ages/fgm-qld-15.html)
• Listed below are the true mangrove species that
  grow in Queensland. Hybrid plants are indicated
  by the use of an x in the scientific name (e.g.
  Lumnitzera x rosea).
• AcanthaceaeAcanthus ebracteatus Acanthus
  ilicifolius
• ArecaceaeNypa fruticans
• AvicenniaceaeAvicennia marina
• BignoniaceaeDolichandrone spathacea
• BombaceaeCamptostemum schultzii
• CaesalpiniaceaeCynometra iripa
• CombretaceaeLumnitzera racemosa, Lumnitzera x
  rosea, Lumnitzera littorea
• EbenaceaeDiospyros ferrea
• EuphorbiaceaeExcoecaria agallocha
• LythraceaePemphis acidula
• MeliaceaeXylocarpus granatum
• MyrsinaceaeXylocarpus mekongensis, Aegiceras
  corniculatum
• MyrtaceaeOsbornia octodonta
• PlumbaginaceaeAegialitis annulata
• PteridaceaeAcrostichum speciosum
• RhizophoraceaeBruguiera gymnorrhiza,Bruguiera
  sexangula, Bruguiera exaristata, Bruguiera
  parviflora, Bruguiera cylindrica, Ceriops
  australis, Ceriops decandra, Ceriops tagal,
  Rhizophora apiculata, Rhizophora x lamarckii,
  Rhizophora stylosa, Rhizophora mucronata
• RubiaceaeScyphiphora hydrophyllacea