Mangroves as organic records

Mangroves as organic recordsMiguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC

Máster Universitario en Cambio GlobalDoctoradoPrograma Oficial de Posgrado adaptado al EEES

MangrovesDistribution of the recordMangroves:The word 'Mangroves'' refers to a diverse group of unrelated plantsthat share a common ability to live in waterlogged saline soils subjected to regular flooding. They are highly specialised and adapted plants in order to survive in unstable conditions.

Global Mangrove distribution:Mangroves are distributed circumtropically, and are largely restricted to latitudes between 30° N and 30° S. Total mangrove coverage is 18 million hectares, which represents only 0.45% of world forests & woodland.

Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC

MangrovesMangrove types

Of the 80 different species most common are:

Red Mangrove:It usually grows near the shore of the water, has red roots that raise over the water.

Black Mangrove:It grows in higher areas than the red mangrove and its roots spread near the trunk in shapes of fingers.

White Mangrove:It grows in higher areas than the black mangrove and the roots are not visible.

Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC

MangrovesStructure, formation, dynamicsMangrove soils develop through a combination of mineral sediment deposition and organic matter accumulation.The mangrove peat is composed primarily of refractory roots.Because mangrove soils are waterlogged and nutrient availability is low, decomposition of mangrove roots and other plant tissues is extremely slow (only a few mm per year).

Miguel Ángel Mateo MínguezCentro de Estudios Avanzados de Blanes - CSIC

MangrovesApplication examples

Quantification of whole-ecosystem carbon storage:Measured:- tree and dead wood biomass-soil carbon content- soil depth in 25 mangrove forests in the Indo-Pacific regionMangroves are among the most carbon-rich forests in the tropics, containing on average 1,023 Mg carbon/ha. Organic-rich soils accounted for 49–98% of carbon storage in these systems. Mangrove deforestation generates about 10 % of emissions from deforestation globally.

Donato et al. 2011

Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC

MangrovesApplication examplesMangroves and Sea-Level Change in BelizeThe mangrove islands in Belize contain deep deposits of peat (organic matter formed from plants) as much as 11 m.

These peat deposits have accumulated over thousands of years as the climate has warmed and sea level has risen. The peat is composed of the decaying parts of mangroves, that are preserved in the flooded and anoxic soil.

Twin Cays, Belize

McKee et al. 2007Miguel Ángel Mateo Mínguez

Centro de Estudios Avanzados de Blanes - CSIC

MangrovesApplication examples

Mangroves and Sea-Level Change in BelizeThe collected peat sections are radiocarbon-dated to determine their age. The peat record at Twin Cays spans almost the entire Holocene Epoch (10,000 years) and the rise of human civilization. Botanical and chemical analyses show which plants were present and what the environmental conditions were like at various times.This is longest continuous peat record of sea-level change currently known.

Chronology of selected events that occurred over the time period recorded in mangrove peat coresVideo:http://www.youtube.com/watch?v=1o4nz0hbR8U&feature=youtube_gdataMiguel Ángel Mateo Mínguez

Centro de Estudios Avanzados de Blanes - CSIC

MangrovesApplication examples

Multiple proxies of past mangrove ecosystems-780 cm long peat core recorded palaeoecological changes since ~8000 yearsProxies included:- Pollen - stable-isotope (C, N and O) compositions of mangrove leaf fragments- Accumulation rate and relative peat hardness

Mangrove peat core

Light microscope images of Rhizophora (red mangrove) pollen

Wooller et al. 2007Miguel Ángel Mateo Mínguez

Centro de Estudios Avanzados de Blanes - CSIC

MangrovesApplication examplesPollen diagram:- Shows the vegetation groups and pollen concentrations at different depths of the core- Rhizophora mangle (red mangrove) has been dominant at this site for over ~8000 years- The presence of mangrove pollen in the sediments indicates a warm climate and a nearby shoreline at the time the pollen were deposited

Mangroves Other trees and herbs

Depth (m)

Wooller et al. 2007

Miguel Ángel Mateo MínguezCentro de Estudios Avanzados de Blanes - CSIC

MangrovesApplication examples

Peat accumulation rates:A decline in peat accumulation rate at ~7200 cal. yr BP correlates with a decrease in the rate of rise in sea level.

Hardness of peat:Provides physical characteristics of a peat and and is a potential correlation tool with other proxies.

a) Peat-accumulation rates between radiocarbon dates

b) Relative hardness and softness of peat (Penetrometer)

Wooller et al. 2007Miguel Ángel Mateo Mínguez

Centro de Estudios Avanzados de Blanes - CSIC

MangrovesApplication examples

a b c d

a Leaf fragment area (mm²)b stable nitrogen-isotope c stable carbon-isotope d stable oxygen-isotope

Composition of leaf fragments

Stable-isotope (C, N and O) :Stable carbon and nitrogen isotope analyses are useful to track past changes in mangrove floral composition, stand structure and nutrient limitations.

Stable-oxygen-isotope composition recorded variations in the proportion of seawater versus precipitation taken up by past mangroves due to changes in sea-level rise

Wooller et al. 2007Miguel Ángel Mateo Mínguez

Centro de Estudios Avanzados de Blanes - CSIC

Mangroves as a paleo-recordLiterature and web sites

• Buillon (2011) Carbon cycle: Storage beneath mangroves. Nature Geoscience. 4: 282–283.• Donato et al (2011) Mangroves among the most carbon-rich forests in the tropics. Nature Geoscience.

4: 293–297.• Ellison (2008) Long-term retrospection on mangrove development using sediment cores and pollen

analysis: A review. Aquatic Botany. 89, 2: 93-104.• McKee et al (2007) Caribbean mangroves adjust to rising sea level through biotic controls on change in

soil elevation. Global Ecology and Biogeography. 16, 5: 545-556.• Wooller et al (2007) A multiproxy peat record of Holocene mangrove palaeoecology from Twin Cays,

Belize. The Holocene. 17, 8: 1129-1139• Wooller et al (2009) Late Holocene hydrologic and vegetation changes at Turneffe Atoll, Belize,

compared with records from mainland Central America and Mexico. Palaios. 24, 10: 650-656.

• http://www.nt.gov.au/nreta/wildlife/nature/pdf/mangroves/2_mangrove_ecosystem.pdf• http://www.nwrc.usgs.gov/factshts/2004-3126/2004-3126.htm• Video:http://www.youtube.com/watch?v=1o4nz0hbR8U&feature=youtube_gdata

Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC

Acknowledgements:Special thanks are due to Kathrin Bacher for her strong contribution in the elaboration of this presentation.

Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC