This review has been prepared by Dr Dick Watling, and is founded on nearly 40 years of observation and interest in Fiji’s mangrove, assistance as a member of the Mangrove Management Committee since its inception (when functioning) and consultant to the private and public sector on mangrove issues in Fiji.
Currently, Fiji has no national policy, plan or official guidelines for mangrove planting.
This, notwithstanding, there has been a plethora of interest in mangrove planting, primarily from NGOs and by the public as a result of corporate social responsibility initiatives, but also by the Ministry of Forestry’s 30 Million Trees In 15 Years planting initiative which includes mangroves, and by the Ministry of Environment requiring a 6x replanting offset of the area of mangrove lost to approved conversions for tourism, industry, residential estates etc.
The conclusions reached from a literature review, the purpose of which was to articulate ‘Best Practice Mangrove Planting’ in Fiji so that it can meaningfully support Fiji‘s ‘Low Emission Development Strategy 2018-2050’ (LEDS). None of the recommendations are ground-breaking or new.
Fiji is way behind in appreciating the lessons learned in many countries with much larger mangrove resources and which have suffered far greater losses to their mangrove resource. Many of these countries failed to heed the warnings of experienced mangrove restorers in the 1990s and enormous quantums of resources have been wasted with the concomitant development of cynicism in many coastal communities.
Unfortunately today, it would appear that the architects of the Blue Economy/Blue Carbon Projects are, for the most part, also failing to appreciate the well-established constraints in respect of mass mangrove planting.
Only with a good understanding of the issues involved and careful selection and development of evidence-based, sustainable best practices in its mangrove planting will Fiji be able to support the confidence placed in mangroves in the LEDs.
The following are draft guidelines drawn from the literature review of international best practice which are applicable for Fiji.
Guidelines for Best Practice Mangrove Planting in Fiji
1) Planting should only be attempted in areas that naturally support mangroves (“reforestation”), and not in areas where mangroves are not known to have grown (“afforestation”).
2) Planting mangroves should not be undertaken in isolation but only after a full appreciation of the risk of any potential planting site in terms of hazard, exposure and vulnerability.
3) Planting in areas which never had natural mangroves may destroy other, equally important ecosystems such as sea grass beds and sub-surface invertebrate life, and a productive habitat for foragers – inshore marine fishery and migrating shorebirds.
4) Effective coastal protection from swell waves and wind require hundreds of meters of mangroves, and thousands of meters are required for significant storm surge abatement, not the narrow belts such as are often produced by current planting projects.
5) Planting mangroves will not stabilise on-going erosion, but well-established mature mangrove stands may resist erosion.
6) Local community involvement in planting initiatives through informed consent, equitable benefit and an understanding of mangrove planting potential and constraints, is an essential pre-requisite for planting projects.
7) Mangrove planting without proper planning can appear to be a short term success yet still fail in the medium and long term. Permanence in respect of planting is an essential consideration prior to planting.
8) Planting mangrove without assured monitoring for success is a wasteful use of resources.
9) Damaged mangroves will usually regenerate naturally over time if left undisturbed. Planting is never as successful as natural regeneration. Wherever possible facilitate natural regeneration (ANR – Assisted Natural Regeneration).
10) Mangroves should not be planted ‘Plantation Style’, such stands are not found in nature and may not develop the same values of natural stands.
Mangrove Management in Fiji – an Historical Reminder
Fiji was one of the first countries to pursue a national policy of sustainable mangrove management and several thousand hectares of mangroves in the Ba, Labasa and Rewa deltas were harvested sustainably in delineated coupes in the early 1940-50’s (Marshall undated; MMC 1986). A national yield of over 50,000 m3 was recorded in 1952.
The management plan specifically identified sustained yield as the goal of mangrove harvesting and the plan correctly determined that natural regeneration would preclude the need for replanting provided the underlying tidal conditions were not altered. No planting was required or undertaken.
Evidence of these harvested areas are readily visible today where uniform stands of well-formed Dogo Bruguiera gymnorrhiza persist.
Recent Mangrove Planting in Fiji
There has, in recent years, been a plethora of interest in mangrove planting primarily from NGOs and by the public as a result of corporate social responsibility initiatives. This is because of ready access, ease of accomplishment of planting, the lack of appropriate policy or best practice guidance and a virtual absence of sustainable mangrove management by the regulatory authorities.
It is encouraged by the Ministry of Forestry 30 Million Trees In 15 Years planting initiative which includes mangroves, and by the Ministry of Environment requiring a 6x replanting offset2 of the area of mangrove lost to approved conversions for tourism, industry, residential estates etc.
A significant area of mangroves has been planted piecemeal in Fiji over the past 20 years (visit, for instance, https://www.mangrovesforfiji.com/ ). https://www.youtube.com/embed/2N5gsqZYWHA?feature=oembed
Some of it predates this – for instance the stand adjacent the Queen’s Road at Korotogo which has had regular replacement and extension plantings over three decades thanks to OISCA and commitment from Korotogo village.
A touted ‘success’ is at Suva Point adjacent the Maritime College which is the result of almost continuous planting and infilling over the past 15 years in an area which has clearly accreted because of the construction of a groyne.
Overall there is very little evidence of any significant success of mangrove planting in Fiji in contrast to areas of natural regeneration of mangrove.
It is a well-trodden path worldwide that when tree planting programs of any sort are initiated to loud acclaim, there is minimal or an absence of a professional review of planting success at an appropriate interval thereafter.
So it is for Fiji’s mangrove planting to date, however, Fiji‘s ‘Low Emission Development Strategy 2018-2050’ (LEDS; MoE 2018) provides the view of a former Director of Fisheries ‘that only 6-7% of seedlings survive 12 months after planting’. PDF Embedder requires a url attribute
Mangrove Management Policy or Guidelines, and Fiji‘s ‘Low Emission Development Strategy 2018-2050’
Currently, Fiji has no national policy, plan or official guidelines for mangrove planting. A national mangrove management plan (MMC 2013) has not been endorsed and no apparent action has ensued to replace or amend it, or provide official alternatives.
It would appear, however, that the LEDS has become the guiding document as Fiji’s mangrove is seen to play a key role. The strategy’s foreword by the Prime Minister Hon. Voreqe Bainimarama states:
We all should be proud of the Fiji LEDS as it is among the first long term emission reductions strategies in the world to address the Blue Carbon Sector – and in our case, that “blue” focus is particularly honed on Fiji’s vital mangrove ecosystems. We’ve seen the wide-ranging benefits of cultivating the blue sector first hand: reviving and restoring our mangroves not only sequesters carbon, but it allows sustenance of our people’s livelihoods with a constant supply of fish and other marine organisms.Prime Minister Hon. Voreqe Bainimarama
Fiji’s Low Emission Development Strategy 2018-2050 (MoE 2018) states ‘The scientific basis for the required offset is unclear, except that it is twice the area recommended in the only mangrove carbon emission study done to date in Fiji’.
The confidence that mangrove ecosystems can play a significant role in contributing to meeting the emission reductions that the LEDS articulates is driven by a growing understanding worldwide that mangroves can sequester and store large amounts of carbon dioxide from the atmosphere, and the carbon buried in mangrove sediments of mangroves can remain there for millennia if left undisturbed, making them critical long-term carbon sinks.
These high levels of above ground and below ground carbon stocks have elevated the importance of mangroves in climate change mitigation and adaptation, and in addition because successful restoration and conservation activities can also be used in nationally determined commitments or in voluntary carbon markets (MacKenzie et al. 2021).
The confidence which the LEDS articulates is based solely on the assumptions made as to how Fiji’s mangrove will be able to contribute in the four scenarios presented.
However, the mangrove data supporting these assumptions are for the most part little more than speculative, they are not rooted in evidence-based data, ecology, forestry and achievable sustainable practices.
As such, so too the economic projections of the blue carbon mangrove must be considered speculative.
To be fair to the authors of the mangrove section in the LEDS document, it is full with caveats about the inadequacy of fundamental data, and also the LEDS is considered a ‘Living Document’ which will be updated as and when data are available.
Whichever approaches are taken, Fiji needs to carefully select and develop evidence-based, sustainable best practices in its mangrove planting.
This like many other countries before it, it is patently failing to appreciate and practice, at present.
Tree planting now dominates political and popular agendas and is often presented as an easy answer to the climate crisis, as well as a way for corporate companies to mitigate their carbon emissions, but sadly, it isn’t as simple as that. When people plant the wrong trees and/or plant in the wrong place, it can cause considerably more damage than benefits, failing to help people or natureDi Sacco et. al. 2021
Mangrove Planting – Lessons Learned
Mangrove Afforestation On Inter-Tidal ‘Empty’ Areas
Mangrove planting in Fiji today is all but exclusively planted on the ‘empty’ intertidal zone. This is because of ready access, ease of accomplishment of planting and the lack of appropriate best practice guidance and management.
It is encouraged by the Ministry of Forestry’s 30 Million Trees In 15 Years planting initiative which includes mangroves, and by the Ministry of Environment requiring a 6x replanting offset4 of the area of mangrove lost to approved conversions for tourism, industry, residential estates etc..
However, it has been accepted in the scientific community for over 20 years that mangrove afforestation on inter-tidal areas amounts to ‘conversion’ of a valuable habitat (Lewis 1999), which is the 2nd of his five Principles of Mangrove Restoration:
2. Do not build a nursery, grow mangroves and just plant some area currently devoid of mangroves (like a convenient mudflat). There is a reason why mangroves are not already there or were not there in the recent past or have disappeared recently. Find out why.Lewis 2005
……the use of the terms “restoration” or “rehabilitation” in such cases is inappropriate, since intertidal mudflats have not been covered in mangrove forests before. Such efforts should therefore rather be termed “afforestation”. Although generally poorly acknowledged outside the scientific community, these intertidal mudflats represent a rich and productive ecosystem in themselves, providing an important habitat that supports high densities of intertidal benthic invertebrates and fulfilling a range of key ecological functions.Erftemeijer & Lewis 1999
More recent analyses are more direct in their distinction between best and unsustainable practices, providing a strong indication of a worrying trend which Fiji is indubitably following:
…….successful rehabilitation is still challenging to achieve at scale, and current rehabilitation projects around the world fail because key ecological thresholds and rehabilitation best practices are ignored, as when planting in low-intertidal locations that are not suitable for mangrove growth…….Work is required to overcome key socio-political hurdles, including lack of training, unclear land tenure and unrealistic planting targets set by national governments or NGOs that encourage and incentivise rehabilitation efforts in unsuitable coastal locations.Saintilan et al. 2021
Current mangrove planting schemes aimed at reversing global losses are prioritising short-term increases in area over long-term establishment. Without sound, evidence-based restoration policies, this approach could accelerate the demise of mangrove forests and the ecosystem services they provide.Lee et al. 2019
…….. ambitious, short-term mangrove restoration projects often plant mangroves on lands that are not owned by anyone. Such lands are frequently low in the intertidal frame and are therefore unsuitable for mangrove growth, thus ultimately leading to the failure…..The key performance indicators of restoration success should include indicators of socio-economic sustainability rather than simple measures of mangrove propagules being planted and mangrove area being created,Lovelock & Brown 2019
The Philippines has lost nearly 70% of its natural mangrove cover since the early 1900s. As a result, large investments have been made to restore mangrove forests and the many ecosystem services that they provide. Most of these restoration efforts have been through out-planting of Rhizophora sp. seedlings, many of which have failed because the proper hydrological and ecological conditions were not properly assessed. Other afforestation projects involved planting seedlings in inappropriate places (e.g., seagrass beds, mudflats) that resulted in replacing one valuable ecosystem with another…….. mangroves should not be planted in areas that are naturally occupied by other ecologically important ecosystems. The purpose of mangrove restoration should be clear and efforts should be focused on formerly deforested or degraded areas.Sharma et al. 2017
The majority of mangrove restoration/replanting projects in Indonesia have experienced high or even complete mortality (MAP 2007). ……….mangrove rehabilitation efforts in Indonesia, both large and small, have mainly failed. The majority of projects (both government programs and non-government initiatives) have oversimplified the technical processes of mangrove rehabilitationBrown et.al. 2014
We found that about 1000-1200 ha of mangroves …23 sites… have been under restoration with the participation of several governmental and non-governmental organizations……about 200-220 ha showed successful mangrove restoration. The level of survival of the restoration project sites ranged from 0-78% and only three sites showed a level of survival higher than 50%.Sri Lanka – Kodikara et.al. 2017
Why Is Mangrove Planting In Fiji’s Inter-Tidal Zone Likely To End In Failure?
The first and most obvious reason is evidence-based – there is very little evidence of any significant success – the current ‘success’ at Suva Point is the result of almost continuous planting and infilling over the past 15 years, in an area which has likely accreted because of the construction of a groyne.
It is a well-trodden path worldwide that when tree planting programs of any sort are initiated to loud acclaim, there is no professional review of planting success at an appropriate interval thereafter.
So it is for Fiji’s mangrove planting to date, however, the LEDS itself provides the view of a former Director of Fisheries ‘that only 6-7% of seedlings survive 12 months after planting’.
The second reason is even more obvious as Lewis (2005) states in his 2nd Principle of Mangrove Restoration – ‘if there are no mangroves at a particular site, especially the low inter-tidal zone – there must be a good reason for it’.
This is certainly the case in Fiji where the mangrove environment has been stable (as measured by Relative Sea Level Rise) for much of the last 6,000 years of the Holocene and more particularly the last 2,000 years (Saintilan et al. 2021).
Mangroves generally fruit continuously as recorded in Fiji (Tyagi 2004) and have no plant competitors.
As such the constraints that have prevented an invasion of the mudflats for the past 2-6,000 years at least, can be expected to impact any planting on the mudflats today which will in any case be accentuated by sea level rise.
Fiji Government is a member of IUCN and as such should be aware of IUCNs position on replanting mangroves, prepared by its Mangrove Specialist Group7 which responds with four reasons to counter simplistic calls for mass planting (IUCN 2017 & 2020; Attachment 1):
1. there is a danger that an emphasis on tree planting distracts from the priority, which is to conserve what we have. Old-growth natural forests are irreplaceable………..
2. the recent history of mangrove planting and restoration is a sorry one. Studies from around the world have shown that most attempts at mass planting of mangroves fail……..
3. even when newly planted mangroves do survive and grow, the resulting forest may be very different from a natural one………………
4. growing and planting mangroves can be very expensive and time consuming. If planting is not necessary, then this diverts funds from other conservation activities and breeds cynicism. A third reason is that the two species of mangrove which are the fringe colonists of mangrove habitats in our neighbours to the west – Vanuatu and the Solomons and elsewhere in south east Asia – Avicennia marina and Sonneratia spp. do not occur in Fiji. Fiji’s four Rhizophoraceae mangroves (Bruguiera gymorrhiza, Rhizophora stylosa, R. samoensis and R xselala) which constitute almost the entire national mangrove resource are not fringe colonists where they occur elsewhere.
What is the Regulatory Framework in respect of Mangrove Planting and Afforestation?
The mudflats of the tidal foreshore are not the empty spaces which they might appear to be, they constitute a variety of ecologically important ecosystems with values that complement those of mangroves and offshore coral reefs.
And as such are a coastal resource which are intricate in the sustenance of the coastal fisheries and those Fijian communities which have relied on the fisheries since their first arrival in these islands (Lee et al.(2018), Morton (1995) and Morton & Raj (1990), Singh (2019)).
Section 3 (2 & 3) of the Environmental Management Act 2005 (EMA) determines their inclusion as matters of national importance which requires application of the Act in respect of their utilisation:
3.-(1) ……..Environmental Management Act 2005
(2) The purposes of this Act are-
(a) to apply the principles of sustainable use and development of natural resources; and
(b) to identify matters of national importance for the Fiji Islands as set out in subsection (3).
(3) A person required to perform any function under this Act relating to the use and utilization of natural and physical resources must recognize and have regard to the following matters of national importance:
(a) the preservation of the coastal environment, margins of wetlands, lakes and rivers;
(c) the protection of areas of significant indigenous vegetation and significant habitat of indigenous fauna;
(d) the relationship of indigenous Fijians with their ancestral lands, waters, sites, sacred areas and other treasures; or
As such any planned afforestation of tidal mud flats with mangroves (including projects by government ministries), would need determination through the EIA Process 8 .
In addition, the Traditional Fishing Rights Owners will need to be consulted in respect of compensation for Loss of Fishing Rights.
This is not a straight forward issue, firstly the communities who live adjacent to foreshore areas and have traditional usufruct access to those areas are often only a small portion of the TFRO, as registered, and who all share in any compensation award.
Secondly, mangroves are not part of the current REDD + project which is designed to provide an agreed reward system for landowners who participate.
At present there appears to be no applicable compensatory means for the potentially affected TFRO or those communities most closely impacted by any mangrove afforestation.
What Is The Area Of Mangrove In Fiji And Why Its Measurement Is So Important ?
As noted above the LEDS is full with caveats about the inadequacy of fundamental data required for sustainable and best practice mangrove management. Nothing exemplifies this more than the foundation knowledge for any mangrove-based projections – an ability to measure the area of mangrove accurately and consistently.
The LEDS notes that figures for the area of mangroves in Fiji vary, and it includes five published/officially presented recent estimates of: 48,317 ha (2013), 38,500 ha (2015), 42,460 ha (2018), 49,500 ha (2018), 52,000 (2018).
The LEDS correctly goes on to note this 25% difference as “significant and will require considerable additional data collection and analysis to resolve”. A similar recommendation on the critical importance of an accurate national figure was made in Fiji’s Mangrove Management Plan 1985-86 (MMC 1986) and its replacement in 2013 (MMC 2013).
An inability to accurately measure the area of mangrove, either nationally or regionally, fatally undermines the foundation on which predictions can be made, because all the economic projections are ultimately founded on changes in mangrove area and to a much lesser extent in Fiji, in its condition.
Further confusion on this critical issue is a recent paper which reports that Fiji’s mangrove area is 65,243 ha, raising a 25% to a 40% difference in recent estimates of mangrove area.
Cameron et al. (2021) is the first published response to assist Fiji’s LEDS ‘develop management responses including the potential to develop forest carbon projects’.
It bases its assessments of mangrove area and loss on two sources – the Global Forest Watch (Hansen et al. 2013) and GIZ, SPC, SPREP PacGeo9, both of which are viewed with considerable scepticism by observers in Fiji, both by those with an understanding of what is happening on the ground, and those with a good understanding of satellite imagery10- as such it is ‘not fit-for-purpose’.
Until such time as Fiji Government is able to resource its own capability of accurately measuring mangrove area and its changes over time (based on the same or suitably calibrated data set), and ensure that there are personnel available to ground truth the results, then the hoped for scenarios and apparent successes of the LEDS will never gain credibility.
What Is The Potential For Restoration Of Mangroves ?
Mangrove afforestation of low-tide mud-flats is not a Blue Carbon opportunity for Fiji.
Apart from the Fijian experience showing it to be highly unsuccessful as in most places world-wide where it has been undertaken, it is internationally considered unsustainable and bad-practice – except in certain circumstances such as the Sunderbans, Bangladesh for stabilising fast-accreting deltaic mudbanks. Nothing comparable occurs in Fiji.
Cameron et al. (2021) acknowledges this by excluding (through omission) afforestation activities from consideration –
“In the context of Blue Carbon in Fiji, for instance, ARR projects could involve the restoration of mangroves degraded by activities such as agriculture (e.g. conversion to sugarcane), clear-felling, dredge spoil placement, or damaged by tropical cyclones (i.e. reforestation or revegetation).Cameron et al. (2021)
Their omission, being no comment at all on the sustainability or feasibility of mangrove afforestation, or the widespread afforestation attempts being undertaken in Fiji at present is counter to the stated purpose of their study ‘Results were then framed within the context of developing management responses, including the potential to develop forest carbon projects’. This is a serious dis-service for the Fijian Government in its wish to ensure that the LEDS as a “living” document may be updated with reliable data and guidance:
The Fijian Government reserves the right to periodically update the Fiji LEDS, as may be needed, to ensure validity, transparency, and accuracy over time. Most notably, the Fijian Government understands that not all data relating to GHG emissions from the different sectors in the LEDS are currently fully known, nor are all mitigation actions fully investigated. As such, the collection of additional data and the inclusion of new or improved technology, and its costs over time, will have an impact on future national planning.
The important information required for the LEDS is What is the actual potential (best current knowledge) for Blue Carbon mangrove projects in Fiji.
Cameron et al. (2021), in the best review to date which includes field work in Fiji, identify the following potential mangrove restoration projects comprising the reforestation or revegetation of:
Mangrove areas converted to agriculture
Historically significant coastal areas have been converted to sugar cane and some for rice, the last being Raviravi in Ba in the 1970s.
Over time these have become for the most part productive and titles issued. Lal (1990) provides a detailed account of the economics of such conversions if natural resources are appropriately included.
Given the significance, level of development and tenural sensitivity of all coastal areas on Fiji’s main islands, there is little to no chance of these reverting to mangrove even under significant relative sea level rise.
Clear felling of mangrove
Cameron et al (2021) could not accurately assess the level of large and small scale clear felling of mangrove but believed it to be low and they did not comment on whether planting would be necessary in such cases, or whether or not regeneration would be sufficient over time.
Small scale commercial and subsistence mangrove harvesting has long been known and continues to be an issue of some local but not national concern.
This is clearly an issue of mangrove management rather than a Blue Carbon opportunity.
Dredge spoil placement
Cameron et al (2021) identify 33 ha of mangroves lost to dredge spoil placement but this does not include mangrove loss in the Labasa delta – (c.15 ha; MMC (2013)) and verified but not quantified lesser areas at the mouth of the Sigatoka R., the Nadi R. delta and the Navua R. removed in the past decade.
Wherever, dredge spoil is placed in mangroves it alters the hydrodynamic regime and can affect mangroves in a variety of ways. More often than not it kills all the mangroves and becomes a terrestrial habitat and is unavailable for mangrove restoration.
In certain circumstances where the hydrology is only slightly altered small areas of the disposal do become colonised by mangrove regeneration, but this substitute is never a replacement of the original IUCN (2020).
Dredge spoil placement in the mangrove causes a significant loss of mangroves which is avoidable and completely incompatible with the LEDS and competent administration of the Environmental Management Act (refer MMC 2013).
It is a remarkable and unfortunate fact that by far the most detailed and comprehensive Environmental Impact Assessment Guideline available today written for Fiji’s circumstances of any sector, is that for dredging and river improvement by Tortell et al. (1992). A document completely ignored by the Ministry of Waterways and Environment with nothing provided to replace it11.
Even though mangrove area estimates of Cameron et al. (2021) are considered not fit-for-purpose (refer above), the study concludes that 77% of all mangrove cover losses between 2001-2018, amounting to 870 ha, were caused by four cyclones.
This is by far the largest driver of mangrove cover loss identified by the study and there is no reason to believe that cyclones were more or less common or severe during that period and the relative magnitude of cyclone impacts as compared to others will not be affected.
It strongly reinforces a conclusion from another wide-ranging review:
………..studies describe repeatable types of impact and a variety of responses of mangroves that make them ecologically resilient to high velocity winds, and which have served to advance the notion that mangroves are disturbance-adapted ecosystems.Krauss and Osmond 2019
It is important to understand, however, that loss of mangrove cover identified remotely does not equate with mangrove mortality and as such potential opportunities for restoration / Blue Carbon projects.
Cameron et al. (2021) go on to discuss at length the issues associated with cyclone damage to mangroves either through physical damage to vegetation from severe winds or hydrological changes brought about by sediment stripping or loading during accompanying storm surge and extending this to the potential for Blue Carbon projects and other management interventions.
This is an extensive and detailed coverage of what is clearly a very complex, site and event specific subject which is receiving a significant amount of research internationally. As such it is a very useful account for the LEDS consideration of mangrove Blue Carbon potential, it is, however, the briefest of snapshots in terms of applying the complexities to Fiji’s circumstances.
The paper’s final word on the subject is a telling reminder to all and is very relevant as well to the unsustainable mangrove afforestation initiatives currently being encouraged in Fiji.
Finally, given the long-term recovery of mangroves is often dependent upon the restoration of hydrological regimes as well as both the frequency, intensity and disturbance legacies of TCs, successful interventions would need to be framed against the degree of risk of future reoccurrence undoing carbon gains –
‘permanence’…….an increase in the frequency of the most intense storms (e.g. TC Winston) and the amount of rainfall produced combined with an increased poleward expansion in the range of TCs creates significant uncertainty and risk for mangrove restoration projects.Cameron et al. 2021
Cameron et al. (2021) aside there is very little record of cyclone damage to mangroves in Fiji from other sources.
Anecdotal accounts from long-time observers in Fiji generally relate localised impacts and considerable variability in severity, much the same as observations of impact in the native forests.
Jaffar (1992) noted the physical effect of cyclones is generally restricted to a narrow external fringe of mangroves with broken branches and leaf stripping.
Sykes (2017) describes serious damage to a deltaic mangrove stand in the Sabeto River following TC Evan in December 2012, natural regeneration has ensued but is far from attaining full coverage in 2021 Google Earth images (pers.obs.).
In Queensland, Asbridge et al. (2018) provide a detailed account of the damage caused by Category 5 TC Yasi and the nature, extent and severity of damage especially to Rhizophora stylosa (Fiji’s almost exclusively dominant ‘front of the mangrove’ species in exposed coastal areas).
The lack of recovery was attributed to sediment-stripping,
‘…..to the inability of R.stylosa to resprout from remaining plant material and persistent inundation due to a decrease in sediment elevation thereby preventing propagule establishment’.Asbridge et al. 2018
However, there are two important studies which were commissioned specifically to determine mangrove rehabilitation and/or management (including reforestation) requirements in Fiji:
RESCCUE (2016) provides a descriptive account of the damage to mangroves in several areas of Ra Province following TC Winston within an ‘integrated coastal management’ approach supporting ICM implementation activities including mangrove planting.
The report includes pre and post TC Winston mangrove assessments and prepares for surveys to identify mangrove planting areas. The project area included the Viti Levu Bay study site of Cameron et al. (2021) where ~307 ha of dogo Bruguiera gymnorrhiza damaged by TC Winston was not recovering and as such made it ‘ a potential option for an augmented or assisted recovery (ARR) blue carbon project ……. but further research is required in order to assess the biophysical factors limiting recovery which would help determine the feasibility of interventions.
Greenhaigh et al. (2018) provides a same project follow up to RESCCUE (2016) to document the benefits and costs of mangrove restoration. However, no further research was undertaken of mangrove condition, and no mangrove reforestation in the areas of destroyed mangrove vegetation was undertaken, the conventional ‘build a nursery plant the mudflats’ had eventuated.
The reasons for this varied but in general planting was not considered possible because of the density of the dead and downed vegetation, and some villages were more interested in planting in front of the village in the understanding that mangroves would protect the village from climate change and future storm surge (RESCCUE (2016), Sykes (2017); Spalding et al. 2014, Naikatini pers.comm. (2021)).
It seems evident that the planting evaluation surveys and community collaboration required for successful planting projects was not what is required (see for example Wodehouse & Enright 2020 – Attachment 2; MAP 2021).
IAS-USP (2018) reports on a study in the Ba delta 30 months after the passing of TC Winston with one objective being ‘to suggest and map areas that would be suitable for reforestation’.
A total of 26 vegetation plots were sampled with six vegetation communities identified – two of these were terrestrial (old gardens and dredge dumps), one was the mixed ‘back of the mangrove’ habitat, and three were mangrove communities. All vegetation communities/habitats were evaluated for reforestation.
Extrapolating this evaluation and using Google Earth, the areas with reforestation potential were then mapped. The only mangrove community which was identified for potential reforestation was the damaged seaward strips of tiri Rhizophora stylosa totalling 2.8 ha.
Whilst it was noted that certain internal areas of mangrove in the delta had been badly damaged, their extent was limited and fragmented, and access was all but impossible because of the dead material remaining and there was in any case regeneration clearly visible (Naikatini pers.comm. 2021).
This was subsequently verified (refer Figure 4 in Cameron et al. 2021).
Irrespective of methodology adopted and/or resources available for these surveys, the area of mangroves available for reforestation/restoration following the close passage of TC Winston the most severe cyclone to ever cross Fiji is remarkably limited.
It is by no means certain that even the 307 ha of ‘dead’ dogo Bruguiera gymnorrhiza at Viti Levu Bay, Ra will, after a further, appropriately detailed investigation be amenable to cost effective reforestation, it may well be that the cause which is likely sediment loading and hydrodynamic changes are so severe that mangrove will no longer grow there.
Or natural revegetation may just take an uncomfortably long time in today’s world of instant need and ecologically irrelevant project time spans.
How Useful Are Mangroves In Protecting Villages From Waves And Storms ?
The role of mangroves in protecting coasts against natural hazards such as storms, tsunamis and coastal erosion has been widely acknowledged. Even so, the level of protection provided by mangroves remains subject to debate.
In Fiji it is one of the most frequently cited reasons for planting mangroves and in the face of actual sea level rise, mangroves are seen as a convenient solution.
An alternative view is that the confidence in such planting is misplaced and can create greater risks to those living in vulnerable coastal locations by inducing a false sense of security (Spalding et al. 2014).
Spalding et al. (2014) is the current standard, a practical guidebook summarising a wide ranging review which yielded three technical reports on the subject (McIvor et al. (2012, 2012a, 2013) and which provides practical management recommendations for coastal zone managers and policymakers.
The report stresses that an appreciation of the risk of any site in terms of hazard, exposure and vulnerability is an essential prior requirement to determining what role mangroves can play.
Refer Attachment 3 for key messages from “ Mangroves for Coastal Defence: Guidelines for Coastal Managers & Policy Makers. “
Pertinent conclusions are that mangrove coastal widths of:
‘Hundreds of meters needed to significantly reduce waves (wave height is reduced by 13-66% per 100m of mangroves) for waves’, and ‘Thousands of meters needed to reduce flooding impact (storm surge height is reduced 5-50cm/km) for storm surge’,Table 1.
There are relatively few coastal locations in Fiji, other than the main deltaic formations where there is a 100m or more of coastal mangrove width, and the potential without undertaking afforestation to plant 100m is even more limited.
As such the potential role mangroves can play in coastal protection in countries with extensive mangrove landscapes, cannot be inferred automatically for Fiji where the potential needs to be applied with great caution lest cynicism and a false sense of security be induced in vulnerable coastal communities.
How Useful Are Mangroves In Stabilizing Coastal Erosion ?
The role of mangroves in protecting coasts from coastal erosion is widely acknowledged and has been demonstrated in many countries where mangroves have been removed from erosion prone coastlines, as has the difficulty in restoring mangroves at such sites (e.g. Naohiro et al. 2012, Lang’at et.al. 2009, Lewis 2000). Ellison (2010) collates some reports from different locations in Fiji where removal of mangroves has resulted in erosion of village foreshore and road batters.
Nunn (2000) found in Ovalau and Moturiki that settlements that deliberately preserved their mangrove fringe report no landward movement of the shoreline in living memory, while those where mangroves were cleared found abrupt shoreline erosion.
In contrast, there appear to be no records where the planting of mangroves has arrested coastal erosion in Fiji.
Coastal erosion is a natural phenomenon worldwide. It is common in Fiji, especially on coasts exposed to the trade winds and tropical cyclones. In its management zonation mapping of Fijian mangrove, MMC (1986) identified coastal and riverine mangrove areas which were zoned for shoreline protection.
There are many resorts in Fiji which will attest to the relatively gradual unidirectional movement of coastal sands by the trade winds, only to find that every decade or so a cyclone moves all the sand back to the starting point, drives it inland or takes it all out to sea.
A rough equilibrium plays itself out but in an inconvenient timeframe for many developers. This situation is now exacerbated by sea level rise, and there are now cases of erosion of village shorelines where it has never previously been experienced.
For the most part current problem coastlines are ones from which mangroves have never been removed, although some have been damaged by cyclones . In such situations, mangrove afforestation of coastal mudflats has no role to play in arresting actively eroding shorelines.
Whilst existing and long established mangrove can certainly resist erosive forces to varying degrees, freshly planted mangrove propagules have no special ability to withstand erosive wave action and they are easily washed away.
One proven traditional method of enabling mangrove colonisation in certain exposed tidal locations is the construction of rock built ‘moka’ walls which can provide initial support for colonising mangrove propagules, but the substrate needs to be amenable for the establishment of a strong rooting system to develop further.
Where villages are under threat from eroding sea fronts and a solution is needed, the most important requirement is to understand the risk in terms of hazard, exposure and vulnerability prior to determining what role mangroves can play (Spalding et.al. 2014).
If there is a clear indication of any potential mangrove planting being reforestation rather than afforestation, then there is a possibility of mangroves having a role to play but only on the basis of the results of a pragmatic risk assessment which needs to include issues of climate change.
Without a positive assessment, the immediate conclusion that mangroves should be planted is a naïve assumption.
The review above provides some clear guidance on internationally accepted best practice for mangrove planting.
Some of this is not practiced in Fiji today, indeed poor practice is the norm and is tacitly or directly encouraged through an absence of policy/guidelines and poor regulatory understanding which is resulting in afforestation attempts of tidal mudflats, the setting of unrealistic planting targets, the adoption of simplistic indicators of success – specifically mangrove propagules planted and area planted, and misplaced confidence of speculative economic projections in Fiji’s LEDS.
It is anticipated that the international profile of the LEDS document will provide the necessary impetus for a significant change to be brought about in respect of the current lack of good or best practice in mangrove management, including but by no means confined to planting in Fiji today.
On the basis of this review the following Mangrove Planting Guidelines are offered for general consideration:
Mangrove Planting Guidelines
1. Planting should only be attempted in areas that naturally support mangroves (“reforestation”), and not in areas where mangroves are not known to have grown (“afforestation”).
2. Planting mangroves should not be undertaken in isolation but only after a full appreciation of the risk of any potential planting site in terms of hazard, exposure and vulnerability.
3. Planting in areas which never had natural mangroves may destroy other, equally important ecosystems such as sea grass beds and sub-surface invertebrate life, and a productive habitat for foragers – inshore marine fishery and migrating shorebirds.
4. Effective coastal protection from swell waves and wind require hundreds of meters of mangroves, and thousands of meters are required for significant storm surge abatement, not the narrow belts such as are often produced by current planting projects.
5. Planting mangroves will not stabilise on-going erosion, but well-established mature mangrove stands may resist erosion.
6. Local community involvement in planting initiatives through informed consent, equitable benefit and an understanding of mangrove planting potential and constraints, is an essential pre-requisite for planting projects.
7. Mangrove planting without proper planning can appear to be a short term success yet still fail in the medium and long term. Permanence in respect of planting is an essential consideration prior to planting.
8. Planting mangrove without assured monitoring for success is a wasteful use of resources.
9. Damaged mangroves will usually regenerate naturally over time if left undisturbed. Planting is never as successful as natural regeneration. Wherever possible facilitate natural regeneration (ANR – Assisted Natural Regeneration).
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