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Topic E1. Mangroves and Sea Level Rise
Richard MacKenzie and Dan Friess
Topic E1. Slide 2 of 27
Mangroves and Sea Level Rise

Introduction
•
•

Global threats to mangrove forests
•
•

Deforestation for aquaculture, charcoal production, or development
Climate change
Mechanisms that have allowed mangroves to keep up with SLR in the past,
present and future
•
•

Current rates of sea level rise
Forecasted rates of sea level rise
Accretion rates
Ability of wetlands to migrate inland
Monitoring wetlands for resilience to SLR
•
•
Rod surface elevation tables
Naturally occurring radionuclides
Topic E1. Slide 3 of 27
Mangroves provide many ecosystem services
1. Supporting
3. Provisioning
5. Cultural
2. Biological
4. Regulating
Topic E1. Slide 4 of 27
Mangrove and Distribution in 2005
25-30o N
25-30o S
Globally: 15,200,000 – 17,000,000 ha
20-35% loss since the 1980’s
(FAO 2003, 2007)
Topic E1. Slide 5 of 27
Climate change: sea level rise
1) Sea-level rise has nearly doubled since 1990 (5.4 cm at 3.2 mm/yr)
2) Sea-level is predicted to increase by 75-190 cm by 2100
Topic E1. Slide 6 of 27
Satellite altimetry reveals that sea-level rise
is not constant across the world
http://www.aviso.oceanobs.com/en/news/ocean-indicators/mean-sea-level/
Topic E1. Slide 7 of 27
Under some SLR scenarios, mangrove will
be progressively lost in Southeast Australia
(modified from Oliver et al. 2012)
Topic E1. Slide 8 of 27
So why does SLR impact mangroves?
Topic E1. Slide 9 of 27
Sea-level Rise → Mangroves
Sedimentation rate (mm yr-1)
14
12
10
8
6
Sedimentation rate = sea-level rise
4
2
Modified from Alongi 2008
0
0
2
4
6
8
10
12
Sea level rise (mm yr-1)
Majority of mangroves are currently keeping up with sea-level rise
Topic E1. Slide 10 of 27
Sea-level Rise → Mangroves
Forces mangroves to retreat landwards but success of migration depends on multiple factors.
Topic E1. Slide 11 of 27
Image from Google Earth, modified by R. MacKenzie.
Topic E1. Slide 12 of 27
Sea-level Rise → Mangroves
•
If mangrove forest floor rises at rates that equal SLR, then
mangroves can be maintained
What makes a mangrove forest floor
rise?
1) Below ground root growth
2) Healthy sediment inputs
3) Leaf litter inputs
Topic E1. Slide 13 of 27
Sea-level Rise → Mangroves
•
If the rate of SLR is greater than the rate at which the mangrove forest floor
rises, then some rearrangement of vegetation will take place or loss of
mangrove will occur
What makes a forest floor fall?
1)
2)
3)
4)
Changes in sediment loads
Changes in nutrient loads
Changes in hydrology
Cutting trees
Topic E1. Slide 14 of 27
Sea-level Rise → Mangroves
Krauss et al. 2010
Topic E1. Slide 15 of 27
Sea-level Rise → Mangroves
•
If the rate of SLR is greater than the rate at which the mangrove forest floor
rises, then some rearrnagement of vegetation will take place or loss of
mangrove will occur
What makes a forest floor fall?
1) Cutting trees or less healthy trees kills
below ground roots or slows their growth
2) Too much or too little sediment
3) High nutrient input can cause roots to
decompose
Topic E1. Slide 16 of 27
Pacific Sea Level Rise Monitoring
Network
1) Identify and protect critical areas naturally positioned to survive climate change
2) Establish baseline data and monitor the responses of mangroves to climate change
Topic E1. Slide 17 of 27
Mangrove
forest floor
elevation
1) Rod surface elevation
tables (rSETS)
Krauss et al 2010
Topic E1. Slide 18 of 27
measurement at time point 1
Topic E1. Slide 19 of 27
measurement at time point 2
Topic E1. Slide 20 of 27
Mangrove forest
floor elevation
2) Radionuclides
Naturally occurring radionuclide:
222Ra
222Ra
210Pb
210Pb
Topic E1. Slide 21 of 27
Topic E1. Slide 22 of 27
Where are we monitoring?
Topic E1. Slide 23 of 27
Summary
•
Sea level rise is the climate change phenomena that is expected to have the greatest
negative impact on mangrove forests
•
Sea level rise will result in shifts in the distribution of mangroves species or
the ultimate loss of species and wetland ecosystems and thus the many ecosystem
services that they provide.
•
Mangroves are resilient ecosystems and in many places appear to be keeping up with
current rates of SLR, this is due to belowground root growth and health sedimentation
rates
•
Mangroves in environments characterized by sediment deficits, low groundwater tables,
and erosion are thought to be the most sensitive to SLR.
•
Mangrove vulnerability and resilience to relative sea-level rise largely depend on
mangrove sediment surfaces, species composition and ability of different species to
colonize new habitats, the slope of the adjacent land relative to that of the land that
the mangroves currently occupy and the presence of obstacles that can impede landward
migration, and the effects of other stressors (e.g., pollution, overharvesting).
Topic E1. Slide 24 of 27
References
Alongi DM. 2008. Mangrove forests: Resilience, protection from tsunamis, and responses to global
climate change. Estuarine, Coastal and Shelf Science 76:1-13.
[FAO]Food and Agriculture Organization of the United Nations. 2003. Status and trends in mangrove
area extent worldwide. By Wilkie, M.L. and Fortuna, S. Forest Resources
Assessment Working Paper No. 63. Forest Resources Division. Rome: FAO.
[FAO]Food and Agriculture Organization of the United Nations. 2007. The world’s mangroves 1980–
2005. FAO Forestry Paper 153. Rome: FAO.
Field CD. 1995. Impact of expected climate change on mangroves. Hydrobiologia 295:75-81.
Gilman EL, Ellison J, Duke NC, and Field CB. 2008. Threats to mangroves from climate change and
adaptation options: A review. Aquatic Botany 89:237-250.
Krauss KW, Cahoon DR, Allen JA, Ewel KC, Lynch JC, and Cormier N. 2010. Surface elevation change and
susceptibility of different mangrove zones to sea-level rise on Pacific high islands of Micronesia.
Ecosystems 13:129-143.
Topic E1. Slide 25 of 27
References
Krauss KW, McKee KL, Lovelock CE, Cahoon DR, Saintilan N, Reef R, and Chen L. 2014. How mangrove
forests adjust to rising sea level. New Phytologist 202:19-34.
McLeod E and Salm RV. 2006. Managing Mangroves for Resilience to Climate Change. Gland,
Switzerland.
Merrifield MA, Merrifield ST, and Mitchum GT. 2009. An anomalous recent acceleration of global sea
level rise. Journal of Climate 22:5772-5781.
Oliver TSN, Rogers K, Chafer CJ, and Woodroffe CD. 2012. Measuring, mapping and modelling: an
integrated approach to the management of mangrove and saltmarsh in the Minnamurra River
estuary, southeast Australia. Wetland Ecology and Management 20:353-371.
Semeniuk V. 1994. Predicting the Effect of Sea-Level Rise on Mangroves in Northwestern Australia.
Journal of Coastal Research 10:1050-1076.
Topic E1. Slide 26 of 27
References
Solomon S, Qin D, Manning M, Alley RB, Berntsen T, Bindoff NL, Chen J, Chidthaisong A,
Gregory JM, Hegerl GC, et al. 2007. Technical Summary, Climate Change 2007: The
Physical Science Basis. In Solomon S, Qin D, Manning M, Marquis M, Averyt KB, Tignor M,
Miller H, and Chen Z (eds.). Contribution of Working Group 1 to the Fourth Assessment
Report of the Intergovernmental Panel on Climate Change. Cambridge, UK:Cambridge
University Press. 19-91.
Tomlinson PB. 1986. The Botany of Mangroves. Cambridge University Press, Cambridge, UK.
Vermeer M and Rahmstorf S. 2009. Global sea level linked to global temperature. Proceedings
of the National Academy of Sciences of the United States of America 106:21527-21532.
Webb EL, Friess DA, Krauss KW, Cahoon DR, Guntenspergen GR, and Phelps J. 2013. A global
standard for monitoring coastal wetland vulnerability to accelerated sea-level rise. Nature
Climate Change 3:458-465.
Thank you
The Sustainable Wetlands Adaptation and Mitigation Program (SWAMP) is a collaborative effort by CIFOR, the USDA Forest Service, and the
Oregon State University with support from USAID.
How to cite this file
MacKenzie R and Friss D. 2015. Mangroves and sea-level rise [PowerPoint presentation]. In: SWAMP toolbox: Theme E section E1 Retrieved
from www.cifor.org/swamp-toolbox>
Photo credit
Daniel Donato, Daniel Murdiyarso/CIFOR, Neil Palmer/CIAT, Rich MacKenzie/USFS, Rupesh/CIFOR.