Appendix 2 - Vegetation Communities and Regional Ecosystems

Note should also be made to the impact of the bech-de-mer industry on fragile island
environments. The demands of the industry for a constant supply of wood to fuel trepang boilers
and smokehouses and to service beacon fires used to guide passage to working boats throughout
the late 1880’s resulted in island ecosystems being heavily denuded (Shnukal 2004). On Masig,
incidents such as the cutting of wongai (Manilkara kauki) stands for trepang drying, to fuel
mission steamers, and for slipway and boat building are reported severely depleted important
seasonal food recources (Shnukal 2004), while the deforestation of Uthu, Yarpar and Auridh
contributed to relocation of inhabitants (Teske, 1991 in Shnukal 2004).
The use of fire is evident on the majority of islands surveyed and there is no doubt that its
ongoing use has been fundamental in shaping and modifying vegetation cover and influencing
habitat diversity across the islands. McNiven (2008) notes the ethnographic record of Haddon
(1935) where fire use forms an integral part of garden preparation and land cleaning in the late
1800’s and evidence of fire is also in the pollen and phytolith record (Rowe 2006, Parr and Carter
2003).
Observations made during the field survey of late season burning of isolated patches of
Sporobolus grasslands surrounded by mangroves on Boigu Island (see Photograph 13, RE3.1.5)
are evidence of targeted actions to manage grassland ecosystems, possibly to maintain access for
fishing and hunting through halting the invasion of mangrove shrubs. Similarly, widespread
annual burning on Saibai Island appears to maintain open Pandanus grasslands and facilitates
hunting of introduced deer. Field observations from the more remote eastern areas of Saibai
however reveals that succession of grassland to dense shrublands of Melaleuca cajuputi subsp.
platyphylla and Acacia leptocarpa may be occurring in the absence of fire. The phenomenon of
rapid landscape change from grassland to melaleuca dominant shrublands and woodlands is
reported in similar landscapes of southwest Papua where the primary disturbance agent is
believed to be Rusa Deer (Cervus timorensis) (Bartolo et al. 2002, Stronach, 2000). Rusa Deer
are known to occur on Saibai, Boigu and on Muralug. Aerial surveys conducted by AQIS in
November 2007 estimate 60 deer on Boigu, and 100 on Saibai (Tim Kerlin, pers. comm. June
2008).
Eden (1974) investigated environmental and human factors affecting widespread areas of savanna
and grassland in southern Papua New Guinea and indicated that these ecosystems, over part of
their extent, result from the combined effects of shifting cultivation and burning. The influence
of past climatic fluctuations on the origins of these formations are unclear, however, their
maintenance appears to be attributable to human activities, in particular burning (Eden 1974).
Evidence from a number of islands, particularly Moa and Dauan, indicates fire has been a
significant control on the distribution of native grassland, particularly on footslope positions
where the vine forest margins have retreated upslope through repetitive burning. Analysis of the
aerial photo record shows that extensive grassland complexes dominated by Imperata cylindrica
(VC17a) on Moa Island, an inferred result of repetitive burning, are relatively stable with little
change in areal extent between 1971 and the present.
While the influence of fire in the present landscape is considered similar to that of aboriginal
burning practices on mainland Cape York Peninsula, it is evident that the fundamental conditions
of climate, soil fertility, drainage and topography also exhibit substantial control on the
vegetation complexity and ecology of the islands. This observation is particularly so for Moa and
can be extended to the majority of the larger continental islands including Badu and Muralug,
which support outstanding biodiversity values.
In comparison to Cape York Peninsula, where coastal and sub-coastal grasslands are under
pressure from exotic weeds and from woodland and rainforest encroachment associated with
reduced burning frequency and intensity (Neldner et al. 1997, Russell-Smith et al. 2002), the
3d Environmental – Torres Strait Regional Ecosystem Mapping Project – August 2008
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