Every Eucalyptus species in one Arboretum

Dr Dean Nicolle, who planted his first eucalypts at a fledging arboretum in Currency Creek when he was 15, has dedicated his life to this diverse and intriguing group of trees.
Currency Creek Arboretum is 32 hectares and planted with 95% Eucalypt species in rows, as Dean describes it “a zoo of trees”.
Dean Nicolle’s speciality is Eucalypts, and it has been since he was a kid. Dean says, “Some people describe me as a gumnut or ‘eucalyptologist’, but I am a botanist, ecologist and arborist specialising in the eucalypts. The arboretum is somewhere to plant my trees, and it is mainly used for research and education”. It was set up on land bought by his parents, and now entirely self-funded.
Dean explains “Most eucalypt species I have tried to grow, with varying degrees of success. I would have 900 or more species here from all over Australia, from seeds I collected in the wild. I usually plant four of each species collected. If I just plant one of that species, I might end up with a poor specimen. By planting more, I get a sense of the variation.”
There are over 900 species and subspecies of Eucalypts in Australia, and it is Australia’s most dominant group of plants. Dean has around 8000 members of the Eucalyptacea represented at Currency Creek, including Angophora, Eucalypts and Corymbia.
When he was 14, Dean read that E. rameliana was presumed extinct in the Alfred Murray ranges, and he made it his mission to rediscover this species. Dean and his supportive family made three separate trips to the Gibson Desert over an 18month period in a quest to find this species - they were unsuccessful, but someone else rediscovered this plant six months later. “Turns out we were looking in the wrong place” says Dean. “I now have it growing at the Arboretum”.
“When I was 15, I went on a field trip with my Dad to South West WA collecting vouchered herbarium eucalypt specimens and seeds. These were the first trees I planted at Currency Creek. The individual trees are the oldest at the arboretum, from 1993.” The routine he developed then still stands true today - he goes on field trips one year to collect seeds from wild populations, and these are planted out the following year. Dean says “I try to have as many different provenances or populations as possible of the one species. I make an herbarium voucher specimen for each population as well.”
“People have a lot of negative views of Eucalypts. They think they are only big trees, they cause bushfires and they drop dangerous branches without notice. But they are a group of trees that is very diverse. When people come here and see the diversity, especially the colourful flowering Mallee forms, it really changes that negative thought process. I love showing people the diversity in eucalypts. Lots of smaller species that are very ornamental, such as E. preissiana which is one that I think people should grow in gardens.”
One that Dean likes with interesting bark is the Deua Gum, E. wilcoxii a multi-stemmed Mallee from mountain areas of NSW (i.e. Deua National Park). Its bark is multi-coloured, a bit like a snow gum. Some of Deans other favourites include:
Warty yate E. megacornuta with large green flowers and bud caps covered with warts that kids love putting on their fingers. Collected from south west WA. Dean has several populations collected in 1995 & 2001.
The Lobe-fruited Mallee, E. Preissiana subsp. lobata. It’s from coastal location near Esperance, and right on the coast of WA. The large yellow green flowers are spectacular, it is shrub-like and multi-stemmed.
Currency Creek Arboretum was set up with research in mind and is used for by many researchers and organisations. For instance, there was a research burn to look at how trees regenerate after fire. Over 90 publications have referenced the Arboretum.
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