North Yilliminning reserve is 22 kilometres from Narrogin on the Narrogin-Kulin Road. The road roughly follows the ancient Binneringie dyke, which has been the catchment divide between the Hotham and Blackwood rivers for hundreds of millions of years.
Coming from Narrogin prepare to turn off into a rest bay under Red Morrell trees on the right, soon after passing Taylor Road. Armstrong road marks the eastern side of the reserve.
Coming from Narrogin prepare to turn off into a rest bay under Red Morrell trees on the right, soon after passing Taylor Road. Armstrong road marks the eastern side of the reserve.
The Binneringie dyke is the catchment divide between the Hotham and Blackwood river catchments
The reserve is underlain by granite bedrock, which is mostly hidden under pale sandy, gravelly, and ironstone soils. There is only one small rock outcrop in a valley near the south west edge.
A breakaway following the highway on the northern edge of the reserve is a contact zone between dolerite to the north (fertile York Gum farm land), and granite (sandy soils) to the south.
Between this breakaway and a horseshoe - shaped breakway/ridge to the south is a gently sloping upland, which has remained for millions of years as part of a major catchment divide. The old and infertile soils consist of shallow ironstone and sandy gravel with pale sandy hollows. An old vegetation map of the reserve had colourful descriptions, such as 'poor wandoo' and 'useless plants and dryandra'. The 2021 image shows the tree coverage at this time, with darker tone indicating Red Morrell and Rock Sheoak dominant areas.
A breakaway following the highway on the northern edge of the reserve is a contact zone between dolerite to the north (fertile York Gum farm land), and granite (sandy soils) to the south.
Between this breakaway and a horseshoe - shaped breakway/ridge to the south is a gently sloping upland, which has remained for millions of years as part of a major catchment divide. The old and infertile soils consist of shallow ironstone and sandy gravel with pale sandy hollows. An old vegetation map of the reserve had colourful descriptions, such as 'poor wandoo' and 'useless plants and dryandra'. The 2021 image shows the tree coverage at this time, with darker tone indicating Red Morrell and Rock Sheoak dominant areas.
This is attractive bushwalking country, but regrowth and ironstone rocks make walking difficult and confusing for visitors. Before a 2022 fire there was a multitude of Cowslip Orchids. Litttle Pink Fairy Orchids with with Sugar, Snail greenhood, Jug, and Donkey Orchids, and a patch of Purple Enamel Orchids. Unlike many surrounding reserves there are very few spider orchids.
A very surprising discovery was numerous Cowslip/Little Pink Fairy orchid hybrids, which have flourished on these soils, and are described in this blog. To see them, park near the picnic table and walk up to the ridge. A narrow dead end track (which can scratch cars) on the left leads south downhill. Check the sheoak grove. Do not pick wildflowers.
Radiometric imagery colours in image 3 show general soil types. Orange-brown indicates brownish fertile York gum, jam and rock sheoak soils. Green indicates gravels. Darker colours indicate paler and deeper sand.
Since the devastating bushfire, rampant regrowth has created a riot of flowering shrubs and herbs which are well worth a visit, although orchid flowering will be suppressed for some years.
A very surprising discovery was numerous Cowslip/Little Pink Fairy orchid hybrids, which have flourished on these soils, and are described in this blog. To see them, park near the picnic table and walk up to the ridge. A narrow dead end track (which can scratch cars) on the left leads south downhill. Check the sheoak grove. Do not pick wildflowers.
Radiometric imagery colours in image 3 show general soil types. Orange-brown indicates brownish fertile York gum, jam and rock sheoak soils. Green indicates gravels. Darker colours indicate paler and deeper sand.
Since the devastating bushfire, rampant regrowth has created a riot of flowering shrubs and herbs which are well worth a visit, although orchid flowering will be suppressed for some years.
 1. 2021 image before fire |  2. 2023 image light =sands |  3. Radiometrics image |
Images below show landscapes in the reserve before and after the fire.
Below top Banksia attenuata deep sand area on the eastern side. No Banksia regeneration.
Below Jarrah pale sand over ironstone on eastern edge. Jarrah resprouted, rapid herb and native grass growth
Below Jarrah pale sand over ironstone on eastern edge. Jarrah resprouted, rapid herb and native grass growth
 2021 dead and living Banksias |  2022 only herbs and weeds | 2024 Rock Sheoaks taking over |
 2021 Jarrah, Calytrix flava in foreground |  2022 All burnt |  2023 vigourous regrowth |
Red Morrell loam below breakaway. The fire was not so severe here because it had almost no understorey. It burnt the base of the trees and caused a leaf drop. Trees repsprouting and growing new leaves and vigourous understorey germination.
 Typical Red Morrell grove |  2022 Leaf drop and trunks scorched |  2024 Trees recovered, understorey germination |
Wandoo plateau stony gravel woodland bounded by a breakaway to the west was completely incinerated. many burnt wandoos are resprouting and there is a germination of wattle seedlings.
 2022 Wandoo upland plain devastated |  2024 Wandoo regrowth profuse acacia germination |
Rock Sheoak stony gravel plateau slope. This area had numerous Cowslip/ Little Pink Fairy Orchids is a degraded rock sheoak woodland. A profuse understorey flower regrowth and sheoak germination is likely to suppress orchid growth for a number of years.
 2021 dense living and dead sheoak woodland |  2022 Area incinerated |  2024 Dense shrub growth and sheoak germination |
Thin wandoo sheoak gravel, sand over gravel on the upland plain. Wandoos reprouted, massive regeneration of the understorey from pre-fire situation
 2021 sparse understorey |  2022 Completely burnt |  2024 dense understorey |
Grass tree group on stony gravel. Most grass trees survived and shrub understorey has been rejuvenated.
This blog shows year by year changes at photomonitoring sites I set up after the fire.
 2021 sparse understorey |  2023 most grass trees survived |  2024 strong understorey growth |
| |