In general, palm leaf rainforests are distinctivecategories of mesophy - PDF document

In general, palm leaf rainforests are distinctivecategories of mesophyll rainforests, with a conspicuousand significant proportion of the upper strata (canopylayer) comprising either feather or fan leaf palms. Itshould be noted that palm leaf size is not used in theclassification of rainforests. The differentiation of palmleaf rainforest requires recognition of the distinctivephotographic signature made by palms when present inthe upper canopy layer. Extensive areas of mesophyllrainforest in the Black Mountain (Kuranda) and Daintreeregions are examples of where palms are dominant inlower sub-canopy layers but do not extend to the uppercanopy layer and are therefore not included in thiscategory of palm leaf rainforests. The formation recognises feather leaf (typicallyArchontophoenix alexandrae) and fan leaf (var. ramsayi) dominated rainforests as two distinctivealliances, although they may intermix. Palm leafrainforests can occur across a range of geologicalsubstrates and topographic positions although thedevelopment of both formations relies on impededdrainage and permanent soil moisture. Swampydepressions on lowland coastal plains provide habitat forthe most extensive occurrences with feather leaf formsgenerally inhabiting swampier localities on soils withhigher nutrient status than fan leaf forms (Tracey, 1982).The feather palm vine forest alliance is sub-divided intoassociations based on topographic, structural and floristicvariations. Typically, associated canopy species includingprovide the floristicexpression of the type aligned most closely toTracey's(1982) original Type 3a rainforest. A floristicvariation with dominant Eubenangee Swamp area, while an upland variant is alsofound on the steep slopes of Bell's Peak (Cairns mapTwo fan palm associations are recognised on the basis ofdifferences in both topography and floristic composition.Upland swamp habitats in the Towalla area are composedpredominantly of provide a rare notophyll rainforest variant.Facts and figures Vegetation alliances Feather palm vine forests (FPVF) Fan palm vine forests (FAPVF)Current extent in the bioregion Area protectedGeographyScattered and highly fragmented remnants occur acrossthe coastal plain from just south of Ingham to Ayton. Theyare best developed on poorly drained alluvium associatedwith the overflow flood plains of both major and minorwatercourses. Small areas are also mapped on thefoothills in the Julatten and Daintree areas and there are anumber of upland examples on the Cairns, Bartle Frereand Thornton Peak map sheets. Strongholds for featherpalm dominated rainforests are the coastal plain fromInnisfail north to Gordonvale, with well preservedexamples contained within the Ella Bay, Russell River andEubenangee Swamp National Parks. Fan palm forests arewell preserved in the Mission Beach (Hull River NationalPark) and the Daintree National Park. The formation has been subject to extensive pressurethrough fragmentation, changes to hydrology and severecyclone damage, particularly in the Innisfail/Ella Bay area.A combination of these factors has helped facilitateextensive invasion by pond apple () into thesub canopy and understorey layers in a number of areas,but most notably in the Daintree and Innisfail areas.Examination of palm rainforests found in unfragmentedportions of Ella Bay National Park suggests that in anundisturbed condition, this forest type is relatively robustand capable of successful and rapid regeneration fromextreme wind damage. Unfragmented examples also tendto be relatively resistant to pond apple invasion. Alterationto hydrology as a result of the drainage of adjacentswamplands has caused changes to the floristiccomposition of fragmented communities.ReferencesTracey, J.G. (1982). The Vegetation of the Humid Tropical PALM LEAF RAINFORESTS Palm leaf rainforests (vegetation codes 4a-5b) © CAMPBELL CLARKE wettropics.gov.au© CAMPBELL CLARKE© DAN METCALFE Key values€Provides foraging habitat for (Southern Cassowary)€Seasonal wetland habitat values€Outstanding aesthetic values€Habitat for rare and threatened plant species. Threatening processes€Changes to wetland hydrology €Exotic weed invasion by species such as (pond apple) and €Ecological edge effects associated with fragmentation.TenureMajor areas are within the boundaries of the WorldHeritage area with some well preserved examplesconserved in the Daintree, Hull River, Russell River andElla Bay National Parks. Isolated remnants scatteredacross the coastal plains of the Wet Tropics are largelyfreehold. Management considerations€Edge effects in fragmented remnants€Exotic species invasion in severely disturbed areas€Hydrological changes caused by adjoining agricultural€Impacts of wildfire on forest margins€Impact of feral animals such as pigs.