Tropical Peatlands

I mirëpritur (welcome in Albanian) to Bog Standard. Today and in subsequent posts we shall enter the world of Tropical Peatlands an expanding and important realm of peaty studies.

Definitions of Tropical Peatlands are somewhat contested. The division over what constitutes a Tropical Peatland lies in the bounding variable; whether it should be latitudinal or climatic. Page et al. (2007) in a study aimed at providing an estimate of the Tropical Peat resource, took the latitudinal approach; reviewing 10 previous inventories of global and tropical peatland to estimate the peat coverage within the tropics of Cancer and Capricorn.  The advantage to such an approach is that it simplifies the task while still providing a good representation of the actual peat coverage. A major disadvantage however, as recognised within the study itself, is that it does not account for differences found in peatland form and process caused by altitude within the tropics, with a move towards temperate forms, indicative of the mid latitudes, with increasing altitude.  

Andriesse (1988) dealt with this by defining tropical peatlands as; those which form and develop under conditions of surplus rainfall and high temperatures generally within lowland areas and expressing a vegetation of swamp forest (Figure 1). This definition results in the inclusion of some areas outside of the tropics such as the Florida Everglades however, is considered by some to be a more accurate means of assessment as the boundaries are based on the climate which controls more directly the environmental conditions and subsequent ecology and therefore form and processes. 

Figure 1: Peat swamp forest in Borneo (source: http://www.flickriver.com/photos/56601430@N05/5257371465/ )

Whichever definition is assumed, Tropical peatlands are a topic of hot discussion in the wake of Global Warming as they are one of the most significant near surface stores of terrestrial carbon in the world (Page et al. 2002). Knowledge of their current area coverage, carbon storage and the stability of the systems are of great importance to the science and politics of climate change.

Quantifying a resource is imperative to implementing a successful management strategy however; the sheer scale of inquiry in this topic can present acute problems in data collection. Within Page et al. (2007), a major difficulty in the estimation was the time period that the data for the inventories spanned. Many data sources were collected  pre 1990 and therefore are inaccuarate due to the rapid development of many of the countries which make up the study area. This development has caused significant deforestation, drainage and agricultural improvement of peatlands.These processes lead to oxidative losses of organic material and have probably significantly reduced the area of peatland previously recorded. In addition peatland that has been converted to agricultural land use may in turn not be recognised in categorizing land while still constituting large peat resources with underlying depths. These difficulties are reflected in the range of values for Area (km²) in Table 1.

 

 Table 1: Maximum and minimum values for area of tropical peatland (km2) (Page et al. 2007).

The Space in which these resources exist is however, not in 2 dimensions, but in 3.Therefore, values for the depth of peat are required however, such data is limited. Previously depth measuremnents have required time consuming field investigation covering large areas to account for differeneces in relation to basement structure and erosional regimes. Within Indonesia some historical data can be sourced however, for the purposes of the Page et al. (2007) study for estimations of the carbon storage and flux, values were obtained by applying average depth values of 1 and 2 metres to the global area estimates.  The values can be seen in Table 2.

Table 2: The lower and upper value range for estimates of carbon storage within Tropical Peatland.

The difficulties faced in summarising the Tropical Peatland resource and monitoring further change maybe lessening  with the arrival of remote sensing as a means of analysis. However, I will discuss this in greater depth in later posts.

Lamtumirë (Good bye in you guessed it................Albanian)

Matt

References:

Andriesse, J.P. (1988), Nature and management of tropical peat soils, FAO, Rome.

Page, S.E., C.J, Banks., J, O’Rieley., 2007. Tropical Peatlands: Distribution, Extent and Carbon Storage-uncertianties and Knowledge gaps. Petalnds international.

Page,S.E., F, Siegert., J, O’Rieley., H-D.V, Boehm., A, Jaya., S, Limin. 2002. The amount of carbon released from peat and forest fires in Indonesia during 1997. Nature, vol. 420, p 61-65.