Regrowth of Eucalyptus ovata seedlings
There were many adult Eucalyptus ovata trees but few young ones when we bought Rubicon in 2007, perhaps due to the previous frequent fire regime. We find that seedlings of Eucalyptus ovata germinate in Wet Heathlands (SHW) after fire and we decided to track two populations of seedlings over successive seasons in order to better understand the population dynamics of this vegetation community.
In September 2012, we selected two quite dense patches of Eucalyptus ovata seedlings in Wet Heathland that was burnt in 2011. We marked out the boundaries of two 10 m x 10 m quadrats in these patches and measured the heights of all Eucalyptus ovata seedling plants and regenerating juvenile plants within the quadrats. We have repeated this procedure within the same quadrats each September since then.
Quadrat 1, taken on 17 September 2012, 17 months after the area had been burnt. Yellow flags mark the positions of E. ovata seedlings and regrowth plants.
Quadrat 1 on 1 October 2015. It shows E. ovata seedlings and regrowth plants marked with blue flags. The vegetation has become taller and thicker and there are considerably fewer E. ovata seedlings and regrowth plants.
Eighteen months after the area was burnt, a large number of Eucalyptus ovata seedlings had germinated in both 100 sq.m. quadrats. In Quadrat 1, still more seedlings germinated the following year before the numbers declined as the vegetation thickened. Whilst in the more densely vegetated Quadrat 2, the numbers of seedlings declined more rapidly after the first year’s flush – and only one seedling remains alive in October 2016.
There were only 13 Eucalyptus ovata plants that regrew from rootstock after the fire. Six of these did not survive but the others are thriving, with their leaves above the ever-thickening sedgy heath vegetation below.
The heights of seedlings and regrowth plants
The figures below show the number of seedlings and regrowth plants and heights of seedlings each Spring from 2012 to 2015.