Lecture 2 - Mangroves Flashcards Preview

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Flashcards in Lecture 2 - Mangroves Deck (13)
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1

what are mangroves?

> woody tress and shrubs
> major vegetation of the intertidal zones of tropical to warm temperate climates
> salt and inundation tolerant
> ecosystems with specific characteristics
> mangroves grow along rivers and into the sea along gradients of salinity
> mangroves inhabit the intertidal zone, are tolerant of inundation and salinity

2

describe water movement in mangrove forests

> water can move fast in mangrove forests with consequences for sediment, leaf litter, fauna, seedling establishment
> total inundation with salt water can occur

3

what are mangroves characterised by?

>strong environmental gradients
- salinity
- water movement
- inundation frequency and severity
- sediment
> seaward zone
> mild zone
> landward zone
> terrestrial forest

4

where do mangroves grow?

> tropical and warm temperate regions
> intertidal zones
> most diverse in species in the Indo-West pacific

5

What ecosystem services o mangroves provide?

> habitat and nursery
> hydrological damping
> sediment trapping
> nutrient cycling and storage
> carbon cycling and storage - sequestration
> forest products
> bioshields protecting coasts against weather extremes

6

compare the diversity of mangroves to other alt impacted communities

> Mangroves
- woody
- 26 families, 69 species
> seagrass
- herbaceous
- 14 families, about 50 species
> salt marsh
- herbaceous
- 18 families (6 dominants)
> low diversity compared to rainforest and coral reef

7

what does mangroves diversity vary with?

> species diversity varies with various factors
> estuaries are on essential mangrove habitat
> diversity increases from south to north australia

8

describe how mangroves are taxonomically and structurally diverse

> 46 species in the Indo-east pacific, 12 Atlantic - west pacific
>mostly woody trees and shrubs + one fern and palm genus
> in Queensland:
> Aegiceras = river mangrove, primarily found along river banks
> Avicennia = grey mangrove, DOMINANT mangrove of Moreton bay
> Rhizophora = red mangrove, typically dominant mangrove in tropics
> further species are: Acrostichum speciosum and lumnitzera racemosa

9

what are some survival strategies mangroves employ to combat the extreme salinity?

> mangroves exclude much salt from water during uptake and several can also excrete salt from leaves
> salinity adaptations include specialised water uptake system and efflux of salt ions in roots and salt glands that actively excrete salt from leaves
> suberin in root endodermis that is a barrier to salt

10

what is a survival strategy mangroves employ to breed?

> they have vivipary
> bear live young
> seeds germinate on the tree, then called propagules
> then they drop to the ground, stick into the soft sand substrate and grow

11

how do mangroves survive anoxic conditions?

> mangroves can grow in anoxic (oxygen depleted) sediment and have different types of roots for anchorage, feeding, aeration
> roots = pneumatophores
- act as snorkels
> specialised root systems to transport oxygen
> aerenchma: tissue for gas exchange to aerate roots and stems
> lenticels = small openings gas exchange (here in pneumatophores)

12

what types of other organisms live within the mangrove community?

> a rich epiphytic algal community on mangrove pneumatophores
> snails;
- graze on sediment during low tide and up on trees at high tide
> Crabs:
- crabs have central role for leaf litter recycling into soil to maintain nutrient status of sediment

13

describe the role of supertidal flats and slat marsh associated with mangrove forests

> high evaporation, cencentrates salts and nutrients (silica, phosphate, ammonium)
> cyanbacteria mats fix air N2 into reactive N and stabilise sediment