Plants are critical to the structure and function of the yellow box – Blakely’s red gum grassy woodland ecosystem, and are a major component of the biodiversity.
A key effect of human-disturbance of woodlands has been the simplification of habitat through thinning and removal of woody vegetation, changes in groundlayer composition and prevention of tree and shrub regeneration.
Vegetation assessments are being undertaken for two key purposes:
- to evaluate the effect of treatments on vegetation structure and composition through time, and
- to provide covariates for inclusion in analysis of faunal responses.
Method of Survey
Vegetation surveys were split into two categories:
- Ground layer – below 0.5m in height and\up to 2cm diameter at breast height (DBH);
- Trees – over 0.5m in height and over 2cm DBH.
Ground layer and soil measurements
A baseline survey of the ground layer vegetation, was conducted in Spring 2007, and soils in Autumn 2008, with the methods and results presented in detail in McIntyre et al. (2010). In summary, the survey was conducted across each of the 96 sites, using 30 systematically-located quadrats (0.5 x 0.5m), per site. The top six plant species (or species groups) were ranked by biomass in each quadrat, and ground cover (litter, litter depth, bare ground, cryptogams, live plant basal area, rock, logs) was measured at four points in each quadrat.
Soil samples were taken in Autumn 2008 to a depth of 10 cm at each quadrat location and pooled to obtain an average for each site.
The following analyses were performed on the soil:
- total Carbon
- total Nitrogen
- Carbon:Nitrogen ratio
- Organic matter
- Electrical Conductivity
- Total soluble salts (%)
- available Phosphorous(Colwell)
All trees over 2cm DBH were measured at each site and a GPS location was recorded for each tree over 10cm DBH. Tree species and health also were recorded. Area coverage of tree regeneration below 2cm DBH was measured. Where amounts of regeneration were relatively small, absolute counts were made. The aim of this approach was to record the tree population structure before treatments were implemented.
- S. McIntyre, J. Stol, J. Harvey, A. O. Nicholls, M. Campbell, A. Reid, A. D. Manning, and D. Lindenmayer (2010) Biomass and floristic patterns in the ground layer vegetation of box-gum grassy eucalypt woodland in Goorooyarroo and Mulligans Flat Nature Reserves, Australian Capital Territory Cunninghamia 11(3): 287–307. here