Vegetation of the Eden Region, South‐eastern Australia: Species composition, diversity and structure

Abstract

Abstract. A classification of plant communities and land systems is presented for the Eden region to assist with the resolution of land use and management conflicts. Vegetation and environmental parameters were sampled at 369 sites and analysed with numerical techniques incorporating elements of the Braun‐Blanquet approach.Land surfaces in the study area were described by means of a land systems analysis. A total of 41 plant communities, 3 with 2 subcommunities, were defined and described on the basis of floristic composition, structure and environmental variables. Descriptions of communities include information on habitat, structure, floristic composition of various strata, distribution and representation in reserves. The distributions of plant communities are interpreted in relation to characteristics of their land systems.Plant communities were grouped into 5 major floristic series: Rainforest, Moist Eucalypt Forest, Dry Grassy Eucalypt Woodland and Forest, Dry Shrubby Eucalypt Woodland and Forest and Heath and Swamp. These groupings are distinguished by their structure, physiognomic attributes, composition of their canopy and understorey strata and habitat. Plant communities are differentiated along gradients of moisture availability, soil properties and temperature. A hypothesis is proposed to explain floristic and structural variation in relation to interactions between moisture and soil fertility gradients. Where moisture is high, tall shrubby eucalypt forest, mesic eucalypt forest and rainforest are thought to be segregated along a gradient of increasing soil fertility. On drier sites, dry eucalypt communities with grassy understorey s are thought to inhabit more fertile soils than those with shrubby understoreys.The biogeographic relations and broad conservation values of the major floristic groupings are discussed. Vegetation patterns in the region are related to a latitudinal sequence which prevails in eastern Australia. A preliminary assessment of plant community distributions shows that the reserve system is not representative of the range of vegetation and landscape types in the region.