Coastal vegetation in Gamaay Country

Littoral Rainforests and Coastal Vine Thickets (also known as beach scrub) is a unique ecological community of coastal vegetation that is directly affected by marine influences (salt spray, tides, storm surge or tropical cyclones).

This community is listed as Critically Endangered under Commonwealth Government’s Environment Protection and Biodiversity Conservation (EPBC) Act (1999) due to severe habitat fragmentation, weed invasion and feral animal activity.

This community provides key habitat for biodiversity (including threatened species of plants and animals) and also contains numerous plant species that are of cultural significance to Indigenous people.

Historically, Littoral Rainforests and Coastal Vine Thickets occurred as an almost continuous but fragmented archipelago of patches along Australia’s east coast. Today the EPBC Act listed community occurs from south of Princess Charlotte Bay in Cape York Peninsula to the Gippsland Lakes region of Victoria in the south.

Mapping of the presence of Littoral Rainforests and Coastal Vine Thickets has been done in the Wet Tropics bioregion. However, within the Cape York Peninsula bioregion, we urgently need to improve our knowledge of the extent and condition of this important ecological community, including north of Princess Charlotte Bay.

The identification and distribution of this community must remain consistent with the federal government legislation listing advice and consider Regional Ecosystem (vegetation) classification, underlying geology and distance from the open coast.

In recognition of this fundamental knowledge gap, Cape York NRM has contracted CSIRO scientists to build capacity amongst the Traditional Owners in Gamaay Country to assess the condition of littoral rainforest and to identify ongoing threats to this threatened ecological community.

Gamaay Country includes the Littoral Rainforests and Coastal Vine Thickets that extend from the Endeavour River National Park at the mouth of the Endeavour River to Knob Point.

During November 2020, with the consent from the Gamaay Traditional Owners, CSIRO scientists Andrew Ford and Matt Bradford used Regional Ecosystem mapping within the Endeavour River National Park to characterise the Littoral Rainforest community into ‘leading-edge’, ‘buffer’ and ‘refugial’ rainforest patches based on their frequency of inundation by storm surge and sea level rise. The plant community was described and measurements taken to determine the wood weight (biomass).

In high rainfall areas (such as Gamaay Country), littoral rainforest has a complex rainforest structure and may include large woody vines, epiphytes, palms and trees with buttressed roots.

These forests have the potential to contain high amounts of biomass and therefore carbon. Most of the littoral forest on Cape York Peninsula lies within Indigenous-managed land, therefore presenting communities with the opportunity to attract possible income from carbon credits by practising approved fire management techniques.

‘Leading-edge’ rainforest type is exposed to frequent inundation and can be critical in protecting communities and infrastructure from the effects of storm-surge, sea-level rise and extreme weather events.

Within the Endeavour River National Park, preliminary results show that the ‘Leading Edge’ Littoral Rainforest Canopy (10-15m in height) was composed of coast she-oak (Casuarina equisetifolia), mango pine (Barringtonia asiatica), Alexandrain laurel balltree (Calophyllum inophyllum) and coconut palm (Cocos nucifera), which is a weed.

The Understory was composed of: wattle (Acacia crassicarpa), beach almond (Terminalia muelleri), banana bush (Tabernaemontana) and Guinea flower (Hibbertia banksii); and the Ground (20%) contained beach grass (Thuarea), Spinifex, Zornia, goat’s foot (Ipomoea pes-caprae), flannel weed (Sida) and pointed spurge (Phyllanthus).

The forest showed significant damage from recent cyclones and associated storm surge. Fallen coconut leaves are inhibiting native plant recruitment, and pig and cattle presence is evident.

This project is supported by Cape York NRM, through funding from the Australian Government’s National Landcare Program