Clearing aliens from public green spaces

A need for follow up clearing of aliens from public spaces is reaching crisis proportions. During 2018-2020 the clearing of alien vegetation from over 20ha of public spaces in Fisherhaven was done by Botfriends. This included the Challenge where monies were donated expressly for that purpose. Detailed data was gathered in terms of levels of invasion, techniques, area and costing. Analyses of the results were preformed and were presented to friends of the Bot, social media and the OSM.

Unfortunately, the Botfriends committee resigned in bulk and they have remained inactive. The gains made with the Ward 8 committee and the Bot River Estuary Forum (BREF) seem to have been abandoned. No follow ups on the gains made have occurred. Their social pages become inactive and the website which contained all the data, was destroyed. Luckily, the 60 plus posts were rescued and now appear on this website.

The last two years were both good rainfall years. The last year was the highest ever recorded rainfall in Fisherhaven. This has resulted in exceptionally good growth of seedlings of alien species, since the competition for water is the main limiting factor in this marginal to dry area. The alien species seedbank was successfully reduced, probably by 50%. The seedbank reduces on an exponential basis, as reported elsewhere on this website. Strong competition results from indigenous species in cleared areas. Many seeds germinated but were outcompeted by indigenous plants. This showed up in the follow-up clearing data where costs were reduced by as much as 60-90%.

With no follow ups in the last 18 months things do not look good. The work done with public money will go to waste, if the existing alien plants are allowed to seed. Most of them will seed in spring. In many areas there are only a few Port Jacksons often growing up through established indigenous plants. In areas where soil disturbance has occurred the alien species are again dominating. The balance is turning in the aliens favour rather than in natures favour. The balance was established by clearing with the right techniques and timely follow ups. We are now running out of time to turn the balance back in natures favour, where nature does most of the work for us.

In addition the risks of disastrous fires are:

  • climbing rapidly,
  • wetlands and biological diversity are been lost,
  • erosion is increasing
  • and all of this is becoming reflected in the Bot River Estuary.

A call for volunteers for clearing aliens

This potential crisis of clearing aliens prompted a call for volunteers to clear the green area of The Crescent in Fisherhaven on 12 February 2022. A small group arrived and in 1.5 hours we cleared almost 2000 square metres.

Cleared alien species and volunteers who cleared them
Alien species cleared by volunteers

Some cash donations were promised to clear additional public land in Sharpie, Fisherhaven. This clearing of alien species was done by Mike and resulted in three piles of chopped down Port Jacksons including some Australian Myrtle.

Alien clearing in Sharpie Street Fisherhaven

The Fisherhaven Rate Payers (FRA) and other private citizens contributed to covering basic costs involved in the project. This is reported more extensively on the FRA page with pictures.

Additional clearing using donated funds to hire labourers

The rest of The Crescent (4 800 square metres) was cleared of alien species. This included Port Jacksons, Australian Myrtle and another Australian import, a large Banksia and over 80 seedlings. There were extensive seedlings (over 1 000) from the mature Bottlebrush trees on the site. A number of these trees were also cut down where they were over shadowing planted indigenous species such as Protea’s. The Bottlebrushes are a problem on this green site and have involved great expense in the past with hundreds of seedlings needing to be removed. In addition New Zealand Christmas trees were removed. These constitute a severe fire risk and were the main culprits involved in the extensive Betty’s Bay fire.

Clearing aliens on the rest of The Crescent

Erf 774 was also cleared of Port Jacksons and pines. The fire risk on the east was severe from 2-3 metre Port Jacksons. The pines come from a mature seeding pine on the neighbouring plot.

Cleared aliens on Erf 774

Some help and poison was provided to clearing the Church and Stormalong intersection site which was cleared by Giuseppe Crispi.

The following pictures are the before and after pictures of the before and after clearing taken from the same position.

Before picture with large Port Jacksons
After some clearing of the Port Jacksons

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