Comparison of effort for each weed type for the last five seasons
This chart shows the amount of effort in the Reserve in each of the last five seasons for each of the weed types targeted. The comparison here is restricted to the Reserve but the equivalent chart for the whole area can be seen by clicking the following link: comparison for the combined Reserve and neighbouring paddocks.
The differences between seasons since the 2019-20 season do not reflect the effort required to control each weed type as they did in previous seasons because we have not had the resources to maintain treatment of each weed type across the whole reserve. The exceptions are Verbascum, Briars, Blackberries and other Woody weeds.
Effort on Verbascum peaked in 2015-16 and then tailed off until the 2020-21 season. It is believed that this is strongly linked to rainfall. A detailed analysis up to 2021 suggested Verbascum prevalence is primarily dependent on summer rainfall but also that other factor(s) affect it. Verbascum prevalence in 2021 was accurately predicted by the 2020-21 summer rainfall, but in 2022 was under predicted by the 2021-22 summer rainfall. Despite summer rainfall in 2021-22 being twice that in 2020-21, Verbascum prevalence was similar in 2022 to that in 2021. Summer rainfall for 2022-23 was similar to that in 2020-21 and so far Verbascum prevalence in 2023 is similar to that in 2021.
Briars, which have been closely monitored since 2011, decreased steadily from an average density across the Reserve of 44 briars/ha in 2012-13 to an average of 2.3 briars/ha between 2021-20 and 2021-22. There has been a slight bounce in 2022-23 to 3.7 briars/ha following the exceptionally wet season of 2021-22 but the density is still less than the 2018-19 season when it was 5 briars/ha. (see also the detailed analysis of briar eradication success).
Blackberries have also been closely monitored and treated since 2010. After falling to very low numbers in 2019, they have rebounded in the last two seasons to very high numbers in 2022-23. Details of these changes can be found at Progress in controlling Blackberries.
Other Woody weeds are not as closely monitored and recorded as briars and blackberries, but based on the data available they have shown a similar decline and then rebound in numbers to that shown by Blackberries.
Otherwise, effort is quite variable from season to season depending on seasonal conditions and available effort.
For a more detailed discussion of season to season differences, see season comparison page.