Limitations In tree and shrub model.

While the model used to segment the crowns of woody plants was generally effective, there were some environments where it was unable to effectively capture these plants, and low shrubs were not adequately detected. These include some of the river systems and water courses and Alluvial Plains/Creekline Woodlands/Herblands sub-assets. This limitation may have led to under-estimation of total canopy and shrub cover scores at some sites.

Insufficient area of target vegetation class covered.

Three of the drone plots analysed covered a total target vegetation class of below the required 5-hectares (Table 11). This was the result of erroneous flight planning, where the Incorrect vegetation was measured. Nevertheless, the assessment of these slightly smaller areas Is expected to produce reasonable results, and results from these sites were not removed from the final analysis.

The K and L indicators were merged to match the approach taken by BioCondition

The Biocondition benchmarks did not separate between indicator K (Native species count for herbaceous species – forbs), and indicator L (Native species count for herbaceous species – other species). In order to make the observations of these indicators comparable with the Biocondition benchmarks, the ‘forbs’ and ‘other species’ were merged for the calculation of indicator condition scores for Northern Territory. The original information of these two indicators has been preserved, so future assessment could separate them if more detailed benchmarks were made available.  For the NT for indication

Calculation of native tree species recruitment

While the Method recommends the use of a formula comparing the benchmark cover for recruitment to the observation, this approach was not deemed appropriate – as the translation of drone derived data did not accurately relate to the field derived benchmarks. As a result, recruitment was calculated as follows: when canopy trees were present, the presence of recruits within field data earned a score of 100, and the absence of recruits led to a score of zero. As more relevant benchmarks are made available, the incorporation of more sensitive recruitment measures will be considered.

Native tree size structure was excluded from the account

The accurate measurement of tree size structure against a benchmark was not deemed feasible. As more detailed benchmarks and individual tree segmentation/classification approaches are made available, this indicator can be revisited for follow-up accounts.

Coarse woody debris calculation

An automatic approach to calculating the length of coarse woody debris was not feasible. As an alternative, this indicator was calculated by digitising (using a line draw tool in Drone-Deploy) all of the visible coarse woody debris within 0.1-hectare sub-plots for each of the sites. The length of each of the lines was then summed, and multiplied by 10, to provide an estimate of the length of coarse woody debris per hectare.

Cryptogam was excluded from the account

Because benchmark data for cryptogam cover was not available, including within the BioCondition datasets, this indicator was excluded from this account. As with the merging of indicators K and L, the observations of cryptogam have been preserved and could be calculated later if benchmarks for this indicator were made available.