Restoration ecology of peatlands Part 1: Opportunities for restoring ecosystem functions and biological diversity

The following essay is split into two parts, and was originally submitted as part of coursework for GY7309, at the University of Leicester. This first part will include the introduction, discussion of peat and peatland restoration, restoration of temperate/boreal peatlands and finally discussions on the restoration of tropical peatlands. Part two will be looking at some of the challenges of restoration and the incorporation of local economic and social wants and needs. I have linked some specialist terms to their wikipedia page for their definitions!

 “Conservation is ultimately not a science but a societal goal – a normative and ethically motivated pursuit – that must include voices other than those of scientists alone.”1

Introduction

Ecosystem restoration is a relatively new conservation strategy, and it has arisen through the recognition that we cannot focus merely on preventing the loss of habitats, but that there is a need to actively rehabilitate or restore damaged habitats2. Restoration attempts to recover the natural resource functions of degraded ecosystems, thereby increasing the provision of their environmental, social and economic services3,4. An ecosystem can be considered as recovered or restored once it contains enough biotic and abiotic resources to be self-sustaining, both structurally and functionally, while demonstrating resilience to normal levels of environmental stress and disturbance5. As ecosystem restoration is dependent on scientific and technical expertise and feasibility, as well as the support and wishes of local communities and local and national government authorities6; there is a clear need to incorporate local communities in ecosystem restoration projects. Ecosystem functions are the “dynamic attributes of ecosystems, including interactions among organisms and interactions between organisms and their environment5. These ecological processes are the basis for the self-maintenance of an ecosystem and examples include decomposition, mineral nutrient cycling and carbon fixation by photosynthesis5. So, how can restoration ecology provide an opportunity to restore ecosystem functions and biological diversity, whilst incorporating the social and economic needs and wants of local communities? Part 1 and Part 2 of this series will be looking at various examples of peatland restoration; from both tropical and temperate regions.

Peat and peatland restoration

Peatlands represent at least one third of the global wetland resource, and are important ecosystems for biodiversity conservation, climate regulation and human welfare7. Peat is formed when decaying organic matter accumulates under water logged conditions8. Natural peatlands are net long-term carbon sinks9, 10, however when degraded or used for peat extraction, these ecosystems turn into large sources of carbon dioxide (CO2)11, 12.  Drainage and extraction leads to a CO2 flux to the atmosphere which can be 400% greater than the long-term sink33 due to the increased respiration and destruction of carbon fixing vegetation11,12,13,14,15. Peatland restoration requires raising the water table and ideally stabilising it close to the peat surface, which must be followed by a re-colonisation of peat-forming species to begin the carbon cycle and anoxic decomposition typical of the ecosystem16. Restoration of northern peatlands has been well studied and documented, with similar tropical peatland studies being at a less mature stage4. Tropical and temperate peatlands share commonalities with their location in waterlogged, acidic and nutrient poor environments4. However, they differ in aspects such as climate and peat-forming vegetation, with tropical peatlands occurring under high precipitation-high temperature climatic conditions and dominated by peat swamp forest trees, while temperate/boreal peatlands occur under conditions of high precipitation-low temperature conditions and dominated by bryophytes, sedges, grasses and low-growing shrubs as the peat forming species4. Therefore, knowledge application between the two types of peatland (northern to tropical or vice versa) is not always appropriate4. With the acknowledgement of the differences between northern and tropical peatlands, the following paragraphs will discuss the different needs when restoring these ecosystems.

Restoration of temperate/boreal peatlands

Northern peatlands have been affected primarily by drainage for agriculture and peat-cutting for fuel and horticulture8. In 1995, approximately 15 million ha of northern peatlands and wetlands in Northern and Eastern Europe and the British Isles had been drained for forestry34. This degradation of peatlands has also been experienced in Canada , where 14% of the country is covered by wetlands17 but over 12,000 ha of peatlands are cutover18. In some regions of Quebec, the peatland losses are extensive, being greater than 70%19. During afforestation projects, the water table of peatlands has to be lowered. This causes changes in runoff production from hillslopes in both the short term (during drainage) and long term (when trees establish)8. This can therefore have significant effects on and throughout water catchments. While there have been studies which have shown total CO2 respiration of a peatland may increase following restoration20; this was attributed to decomposing straw mulch used in the restoration process21 as well as a lack of carbon fixing vegetation and variable moisture conditions22. Other studies have shown that active rewetting of peatlands can decrease respiration of a peatland23, 24. Furthermore, it has been found that peatlands can become net carbon sinks (thereby, their carbon storage functions are restored) within five years of restoration22. This was found in a study of a Canadian peatland which had experienced drainage and extraction, with ecosystem scale restoration leading to an increased storage of CO2 due to rewetting (and thereby a decrease in peat respiration), as well as a significant increase in ecosystem productivity from the increased vegetative cover22. The importance of increased vegetative cover for the increased storage of CO2 suggests biological diversity as being vital for restoring other functions of northern peatlands. Additionally, where the peatlands have experienced complete harvesting, managed restoration has been shown to promote new nature, where cutaway areas have the potential to be used for positive increases in biological diversity25. It is therefore clear that restoration, with proper monitoring, design and management; can provide good opportunities to restore peatland ecosystem functions such as carbon sequestration and storage in temperate/boreal regions, as well as biological diversity; even in the most heavily damaged peatlands.

Restoration of tropical peatlands

Southeast Asian peatlands, when supporting forests, are referred to as ‘peat swamp forests’ (PSF).  As the peat-forming species are typically peat swamp tree species, the peatlands in Southeast Asia have been degraded through not only drainage (a shared cause of northern peatland degradation), but through deforestation and resulting fires4. In 2006, 45% of peatlands in Southeast Asia were deforested, usually for the purpose of establishing timber or palm oil plantations26. This peatland degradation and deforestation has caused significant environmental and socio-economic impacts at both local and global levels with the loss of vital peatland ecosystem services4. This includes their carbon storage and hydrological regulation, with estimates that the CO2 emissions from peat oxidation in drained peatlands of Southeast Asia are in the range of 355 – 874 Mt CO2 per year26. At least one third of this figure comes from degraded tropical PSFs27. Because of the significant CO2 emissions, ecosystem restoration could be one of the most cost-effective measures to reduce peatland CO2 emissions28, 29. As previously mentioned, the restoration of tropical peatlands is at a newer stage than boreal or temperate peatland restoration projects. Page et al. (2009) [4] discuss tropical peatland forest restoration using the example of the former Mega Rice Project (MRP). This is an area that experienced deforestation through plans to convert 1.7 million hectares of PSF to rice paddy fields30. With the failure of the project (with rice being unable to grow in acidic peat soils) most of the former MRP area is now left in a highly degraded condition4. Comparing this to the nearby Sabangau Forest (a relatively undisturbed tropical PSF), it is clear that the restoration of the peatland hydrological functions is the key pre-requisite to establishing a positive or neutral peatland carbon balance, as well as the forest vegetation4. To do so involves damming of canals previously used to transport timber out of the peatland area (which now only leads to further drainage of the peatland), in order to raise water levels. Over a 5 week period following an installation of dams in Sabangau, there was an increase in the water levels in blocked channels of an average of 8cm4. While these results are preliminary, they suggest that blocking canals can have a positive impact on the water levels and hence hydrological recovery of the forest. However, canal blocking at the former MRP illustrated further complications to damming operations; while there was an increase in groundwater table with damming which decreased subsidence and CO2 emissions, there was still an issue of canals “eating” themselves into the peatland; thereby creating extra runoff as well as increased subsidence of peat near canals31. The authors therefore concluded that there has to be improved canal blocking strategies to allow for the restoration of tropical peatlands, which will require better understanding and research into the effects of changes in hydrology and damming on the topography of peatlands31. While it is clear that the opportunity exists for restoration projects to reinstate the hydrological function which is a prerequisite for the return of the biological diversity of tropical peatlands; more work is indeed needed to identify the most effective methods for doing so. Keep an eye out for Part 2, which will look at some of the challenges of restoration and the opportunities of incorporating the social and economic wants and needs of local communities!

References

  1.        Sheil, D. & Lawrence, A. (2004). Tropical biologists, local people and conservation: new opportunities for collaboration. Trends in Ecology and Evolution, 19:634-638.
  2.        Yap, H.T. (2000). The case for restoration of tropical coastal ecosystems. Ocean and Coastal Management, 43 (8-9), pp. 841-851.
  3.        Edwards,  A. (1998) Rehabilitation of coastal ecosystems. Marine Pollution Bulletin, 37, pp. 371–372
  4.        Page, S., Hosciło, A., Wösten, H., Jauhiainen, J., Silvius, M., Rieley, J., Ritzema, H., Tansey, K., Graham, L., Vasander, H., Limin, S. (2009). Restoration ecology of lowland tropical peatlands in Southeast Asia: Current knowledge and future research directions. Ecosystems, 12 (6), pp. 888-905.
  5.        Society for Ecological Restoration International Science & Policy Working Group (SER) (2004). The SER International Primer on Ecological Restoration. http://www.ser.org & Tucson: Society for Ecological Restoration International.
  6.        Higgs, E. (2005). The two-culture problem: Ecological restoration and the integration of knowledge. Rest Ecol 13:159–164.
  7.        Erwin, K.L. (2009). Wetlands and global climate change: The role of wetland restoration in a changing world. Wetlands Ecology and Management, 17 (1), pp. 71-84.
  8.        Holden, J., Chapman, P.J., Labadz, J.C. (2004). Artificial drainage of peatlands: Hydrological and hydrochemical process and wetland restoration. Progress in Physical Geography, 28 (1), pp. 95-123.
  9.        Clymo, R. S. (1984). Profiles of water content and pore size in Sphagnum and peat, and their relation to peat bog ecology. Philos. Trans. R. Soc. London, Ser. B, 215, 299–325.
  10.     Clymo, R. S., J. Turunen, and K. Tolonen (1998). Carbon accumulation in peatland, Oikos-Koebenhavn, 81(2), 368–389.
  11.     Sundh, I., M. Nilsson, C. Mikkelä, G. Granberg, and B. H. Svensson (2000). Fluxes of methane and carbon dioxide on peat-mining areas in Sweden, Ambio, 29(8), 499–503.
  12.     Waddington, J. M., K. D. Warner, and G. W. Kennedy (2002). Cutover peatlands: A consistent source of CO2. Global Biogeochem. Cycles, 16(1), 1002.
  13.     Nykänen, H., J. Alm, K. Lång, J. Silvola, and P. J. Martikainen (1995). Emissions of CH4, N2O and CO2 from a virgin fen and a fen drained for grassland in Finland. J. Biogeogr., 22, 351–357.
  14.     Nykänen, H., J. Silvola, J. Alm, and P. J. Martikainen (1997). The Effect of Peatland Forestry on fluxes of carbon dioxide, methane and nitrous oxide, in Northern Forested Wetlands: Ecology and Management, edited by C. C. Trettin et al., pp. 325–339, CRC Press,Boca Raton, Fla.,
  15.     Waddington, J. M., and K. D. Warner (2000). Effect of peatland drainage and harvesting on CO2 efflux. Phys. Geogr., 21(5), 433–451.
  16.     Vasander, H., Tuittila, E.-S., Lode, E., Lundin, L., Ilomets, M., Sallantaus, T., Heikkilä, R., Pitkänen, M.-L., Laine, J. (2003). Status and restoration of peatlands in northern Europe Wetlands Ecology and Management, 11 (1-2), pp. 51-63.
  17.     Zoltai, S.C. (1988). Wetland environments and classification. Wetlands of Canada. Ed. C.D.A. Rubec. Montreal, Quebec: Polyscience Publications Inc. p 4-26.
  18.     Cleary, J. (2003). Greenhouse Gas Emissions from Peat Extraction in Canada: A Life Cycle Perspective. M.Sc. Thesis, McGill University, Montreal, Quebec, Canada.
  19.     van Seters, T.E. & Price, J.S. (2001). The impact of peat harvesting and natural regeneration on the water balance of an abandoned cutover bog, Quebec. Hydrological Processes, 15: 233-248.
  20.     Petrone, R.M., Waddington, J.M. & Price, J.S. (2003). Ecosystem-scale flux ofC02 from arestored vacuum harvested peatland. Wetlands Ecology and Management, 1 1 :419-432.
  21.     Waddington J.M., Greenwood, M.J., Petrone, R.M. & Price, J.S. (2003). Mulchdecomposition impedes recovery of net carbon sink function in a restoredpeatland. Ecological Engineering, 20: 199-210.
  22.     Greenwood, M. (2005). The effect of restoration on CO2 exchange in a cutover peatland. Open Access Dissertations and Theses. Paper 3649.
  23.     Tuittila, E.S., Komulainen, V.M., Vasander, H. & Laine, J. (1999). Restored cut-awaypeatland as a sink for atmospheric C02. Oecologia, 120: 563-574.
  24.     Komulainen, V.M., Tuittila, E.S., Vasander, H. & Laine, J. (1999). Restoration of drainedpeatlands in southern Finland: initial effects on vegetation change and C02balance. Journal of Applied Ecology, 36: 634-648.
  25.     Collier, M.J. and Scott, M.J. (2008). Industrially Harvested Peatlands and After-Use Potential: Understanding Local Stakeholder Narratives and Landscape Preferences. Landscape Research, 33(4):439-460.
  26.     Hooijer, A., Silvius, M., Wösten, H., Page, S. (2006) PEAT-CO2, Assessment of CO2 emissions from drained peatlands in SE Asia. Delft Hydraulics report Q3943 (2006), p 36
  27.     Graham, L. (2013). Restoration from within: An interdisciplinary methodology for tropical peat swamp forest regeneration in Indonesia. PhD Thesis, University of Leicester.
  28.     Spracken, D., Yaron, G., Singh, T., Righelato, R. and Sweetman, T. (2008) The root of the matter: Carbon sequestration in forests and peatlands. Ed. Caldecott, Ben. Policy Exchange Pub., London
  29.     van Noordwijk, M., Purnomo, H., Peskett, L. and Setiono, B. (2008) Reducing emissions from deforestation  and forest degradation (REDD) in Indonesia: options and challenges for fair and efficient payment distribution mechanisms. Working paper 81, World Agroforestry Centre (ICRAF), Bogor, Indonesia.
  30.     Hecker, J.H. (2005) Promoting Environmental Security and Poverty Alleviation in the Peat Swamps of Central Kalimantan, Indonesia. Institute for Environmental Security.
  31.     Ritzema, H., Limin S., Kusin, K., Jauhiainen, J. and Wösten, H. (2014). Canal blocking strategies for hydrological restoration of degraded tropical peatlands in Central Kalimantan, Indonesia.  CATENA, 114:11-20
  32.     Butler, R. [online] (2013). Australia terminates landmark REDD+ project in Borneo. Mongabay.com. Accessed online: <http://news.mongabay.com/2013/0703-kfcp-to-end-ausaid.html&gt; [9/12/2013]
  33.     Gorham, E. (1991). Northern peatlands: Role in the carbon cycle and probable response to climate warming, Ecol. Appl., 1(2),182–195.
  34.     Paavilainen, E. and Paivanen, J., (1995). Peatland forestry: ecology and principles. Ecological studies 111. Heidelberg: Springer Verlag..

 

Read Part 2 of the series here.

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One response to “Restoration ecology of peatlands Part 1: Opportunities for restoring ecosystem functions and biological diversity

  1. Pingback: Restoration ecology of peatlands Part 2: challenges of restorating, and incorporating the social and economic needs and wants of local communities | EcoPost·

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