Structure and dynamics of grazed woodlands in North-eastern Australia

Data from 75 permanent belt transect sites were utilised for an analysis of the

floristics and temporal dynamics of the woody vegetation of the grazed woodlands

of Queensland, Australia. Woody species abundance, composition and structure

were described based on over 42, 000 individual recorded plants and.Detrended

Correspondence Analysis was used to divide the transects into seven community

types based on floristic similarity. The time between first and last recording varied

between sites, with 17 years between initial and final recording for the oldest site

and three years or less for the 39 remaining sites were recorded. Between first and

last recording events mortality was 2.6% of initial woody plant density per year

while recruitment was 6.796, resulting in an overall increase in woody plant

numbers of 17% of initial density. The woodlands experienced a decrease in basal

area of 0.7% of initial basal area per year despite the increase in density, reflecting

that many the majority of recruits were small plants with minimal basal area.

Despite fluctuation in basal area and density, species composition remained largely

unchanged over time. Size class distributions remained unchanged over time and

followed a reverse-J pattern for most woodland types. Ordination analysis revealed

that a range of environmental factors including temperature, geographic location,

soil type and topography were important in influencing the distribution of

community types. Linear models revealed that that dynamics patterns within the

woodlands were poorly correlated with those environmental factors utilised.