Wheel Cactus Mapping Project

Appeal for Wheel Cactus location records from across the shire (and win a prize!)

Connecting Country is appealing for observations of Wheel Cactus to be lodged onto their Community Interactive Mapping Portal.   Each month, a randomly chosen submitter of Wheel Cactus records will receive a prize (e.g. a natural history book).

 

 

Wheel Cactus (Opuntia robusta) is a major weed species in the broader Maldon area, and a potential risk across most of the Mount Alexander Shire and surrounds (click here and here for further information on Wheel Cactus identification, risks and biology).  On Sunday 17^th April, the Tarrengower Cactus Control Committee (TCCC), with the assistance of Parks Victoria, successfully launched their 2011 control program.  Over 30 eager volunteers swarmed over a private hillside along Watersons Rd, approximately 4 km north-west of the Maldon township, removing smaller plants and injecting larger ones.  (The TCCC holds community control days on the 3^rd Sunday of each month from May to September – contact Ian Grenda on iangrenda@live.com for further details).?

Ian Grenda, a local naturalist and a foundation member of the TCCC, highlights that it’s not just a risk confined to Mt Tarrengower and immediate surrounds.  “Although the largest Wheel Cactus infestations currently occur in the Maldon area, the whole region is at potential risk.  It seems that ravens understand the value of cactus fruits as a food source, and pass this knowledge on to their offspring and other ravens.  Even very small cactus infestations located many kilometres from the main infestation areas can become a major problem due to the widespread presence of ravens in the district.  It’s a particular issue at this time of year because the fruiting stage of the cactus coincides with many young ravens dispersing into new areas.  There is an urgent need to know where there are plants present across the local area, even if an infestation is currently confined to just a single plant on a roadside.”

Rodney Jones, from the Biosciences Research Division within the Department of Primary Industries, was present on the day, and has a deep interest in this invasive species.  “Our team is working to develop a spatial model that aims to efficiently survey new incursions of weeds.  For one of our models, we are analyzing the dispersal of Wheel Cactus by ravens, which unknowingly spread the seeds after eating the cactus fruits.  As our model requires accurate data on actual locations of Wheel Cactus in the broader Maldon area, we have made several trips to record Wheel Cactus infestation sites.  However, in talking with participants at the Community Day on Sunday 17 April, it became clear that there were many more cactus sites than we knew about.”

With these thoughts in mind, Connecting Country has offered the use of their Community Interactive Mapping Portal (CIMP) to assist in the mapping of Wheel Cactus.  The CIMP is a tool that allows any person with access to the internet to submit observations or other activities of interest (e.g. flora, fauna, revegetation, weeds) for particular point locations across the local area.  At present, the CIMP contains only one observation of Wheel Cactus across the whole shire, which clearly under-represents the true picture.  In this instance, all community members are encouraged to submit location records of Wheel Cactus, as well as other associated information, e.g. number of plants (a few/approx. 100/heaps); juvenile or mature (flowering/fruiting) plants; under trees or in open paddock; etc.  ANY records, even just dots on the map are useful, but more accurate records will be more valuable.

Through community observations, we will hopefully gain a much better picture of the extent of Wheel Cactus.  As well as assisting in the scientific research, these Wheel Cactus observations will also help at the local scale by providing the stimulus for targeted control actions to be implemented in a timely manner.  The CIMP can be accessed through the Connecting Country website, or by clicking here .  First-time users of the CIMP will need to obtain a username and password (which is a simple process that can be undertaken on-line), and a help guide for the CIMP is also provided.

Once you have lodged a locality for a Wheel Cactus infestation on the CIMP, you are also able to add additional written information on the extent of the infestation.  Some examples of the types of information that would be useful are provided below:

• “Seers Road; approx. 1 km from western dead end of road; 100 m stretch of isolated cactus plants (some flowering/with fruit) associated with roadside trees; one tree in paddock approx. 50 m from fence/road with scattering of non-flowering/fruiting stage plants underneath.”
• “GPS 37 2.148S 144 1.096E; possible absentee landholder; rocky outcrop with heavy infestation of mature cactus plants with fruit; adjacent paddock on western side with occasional plants scattered through paddock; moderate density of cactus plants under roadside vegetation extending 150 m from rocky outcrop along Blogs Road; no cactus plants in adjacent grazed (sheep) paddock.”
• “Watersons Road; 1 km west of Tarrengower School Road junction; heavy infestation of cactus plants of varying ages along creek line, especially under mature trees; some scattered juvenile plants under adjacent roadside trees.”

Running Tally of Wheel Cactus Records on the Community Interactive Mapping Portal
Pre-May 2011 – 1 record
May/June 2011 – 13 new records
July 2011 - Nov 2011 – 1 new record
Running TOTAL – 15 records