PATTERNS OF SPECIES COMPOSITION AND RESERVE DESIGN FOR A FRAGMENTED ESTATE - MONSOON RAIN-FORESTS IN THE NORTHERN-TERRITORY, AUSTRALIA

Monsoon rainforests occur as small patches in the extensive Eucalyptus -dominated landscape of northern Australia. This distribution presents for formidable conservation problems. On a coarse scale (1:1,000,000) , monsoon rainforests are currently relatively well represented in the existing reserve network. However, inspection at a finer resolution s hows that six of 16 variants are unreserved, and about 18% of plant sp ecies have not been captured by the existing reserve system. Inspectio n of inventory data for 1245 monsoon rainforest patches and 570 associ ated plant species in the Northern Territory revealed very idiosyncrat ic species composition for individual patches and a large number of re stricted species (e.g. 20% of species are known from five of fewer pat ches). Vertebrate distributions were less idiosyncratic, although samp ling effort was far less intensive (45 patches and 58 associated speci es). A minimum selection algorithm (CODA) was used to design a reserve system which captures all occurrences of singleton species and at lea st two representations for all other plant species. This selected 139 patches, with a total area of 6413ha. Inclusion of vertebrate records increased the number of selections only marginally (to 141 patches). H owever, this solution has profound practical limitations: the number o f selected patches is probably politically unacceptable, the managemen t required to protect the patches adequately is beyond the economic al lowance for conservation of all existing NT parks, and the solution do es not adequately consider the spatial arrangement of patches which is probably critical for the maintenance of ecological processes. It is not possible to design an efficient solution in which patches are clus tered together. The conservation of the monsoon rainforest estate will be reliant upon (1) the identification and active intense management of particularly restricted and vulnerable species, and (2) conservatio n planning for the whole landscape, which integrates monsoon rainfores t conservation with that of the surrounding savanna woodlands.