At the IMPACT OAL seedlings of four species, i.e. Eucalyptus cladocalyx, Eucalyptus cloeziana, Eucalyptus grandis and Eucalyptus urophylla have been planted as single-species, as typically practiced in the forestry industry.   

• E. cladocalyx – Commonly known as “sugar gum”, it is often used as a windbreak or shelterbelt, but also has significance for timber and firewood production. The flowers of this tree are also very attractive to bees and it is a significant species in the Western Cape for pollination and honey production. The Australian distribution of E. cladocalyx lies in southern South Australia, and itis one of the most drought tolerant of the larger eucalypts.   

• E. cloeziana – Commonly known as “Gympie messmate”. The good physical properties of the timber, combined with its high durability, renders it suitable for a wide range of purposes, including heavy construction, sleepers and mining timber. Due to this tree’s straight and branch free stem, the wood can be made into a high-quality transmission pole. It has a scattered natural distribution in tropical and sub-tropical areas. It is also distinct from other species used at IMPACT, being in the subgenus Idiogenes. It has low cold tolerance, but high wind tolerance.  

• E. grandis – Commonly known as “Flooded gum”. Flooded gum is an attractive, straight-trunked tree in great demand for its timber or pulp. Its timber is commonly used for flooring, panelling and plywood. This species is appropriate for sub-tropical zones, even humid to sub-humid conditions, but is not suited for areas where frost and snow occur. Although E. grandis grows better under well-watered conditions, it does show tolerance strategies under drought stress. It has also become what may be called the “model eucalypt” being the first to have its genome sequenced in 2014, and widely researched. It is widely grown around the world as a pure species or as one parent in hybrids.  

• E. urophylla – Commonly known as “Timor white gum” and is native to Indonesia. It is used to make a variety of products. This includes pulp, paper, charcoal, poles, posts, panels and furniture. This species has a high tolerance for diseases (e.g. fungal diseases such as Crysoporthe austroafricana and Coniothyrium cankers). This species shows moderate tolerance to drought stress.  

Seeing that monocultures are known to be more susceptible to disease outbreak, we have included mixed-species plots consisting of all four species planted together at the four different spacing to evaluate if eucalypts can benefit from being planted in polycultures. We also included as an industry standard, a commercial clone of E. grandis that was used in several research projects in phase one of EucXylo, and in collaboration with Prof Zander Myburgh we have established a subset of the E. grandis provenance species planted at the E. grandis common garden experiment at Mondi, Hilton, South Africa.