Combining modern technology and traditional expertise is key to ensuring UPM’s latest tree nursery is a roaring success.
UPM’s new tree nursery is already bringing prosperity to Sarandí del Yí, Durazno, a town in central Uruguay. Scheduled to begin operations in March 2022, all available rental flats have been snapped up in order to host the 200 rotating workers running the construction and assembling phases, which started in September 2020.
The nursery will occupy a 100-hectare terrain, of which 18-hectare are dedicated to production and comprises, amongst other facilities, 4.5 hectares of greenhouses, 2 hectares of outdoor nurseries and a large central working hall. It is here that the majority of the 120 new employees will manually classify the best Eucalyptus dunnii and Eucalyptus grandis seedlings by selecting cuttings of a mother plant which, once they grow into fully-formed trees, will supply 10 million tree seedlings to establish plantations that will supply wood to the new UPM Paso de los Toros pulp mill.
“The seedlings are not obtained from seeds but through vegetative propagation, which is the most efficient method of securing the best individuals and growing potential. Only around 50% of the cuttings actually root, so in order to obtain 10 million seedlings we need to produce 20 million cuttings,” says Federico Rey, Head of Nursery at UPM Forestal Oriental.
Those specimens of eucalyptus, especially the dunnii species, have a series of properties which make them very suitable for the production of high-quality cellulose pulp, and therefore make most of the seedling production.
From small seedlings to fully-grown trees
The process goes as follows: the cuttings start their journey in the rooting greenhouse, which needs 95% humidity and a temperature of around 25oC. Forty days later, they are moved to a second greenhouse with lower humidity to encourage growth. Depending on whether it is summer or winter, the growing stage takes between one and three months. Once the plants reach a height of 25 cm, they are moved to the outdoor nursery so the roots and leaves strengthen thus allowing field transplantation, which takes place in either autumn or spring, to be successful.
In between, seedlings need to be classified and pruned, a task that needs to be done manually and carefully as involves many decisions– such as discarding sick specimens. Each worker is based in the central work hall, which is packed with state-of-the-art equipment.
The nursery will incorporate a system of aluminium rolling tables, so the plants can be moved from one environment to another with very little effort. Each 6-metre-long table able to transport thirty trays of plants at a time will move along the nursery by motorized tracks. This mechanisation will not only optimise the movement of the seedlings but also takes care of the workers’ ergonomic needs.
Boosting the local economy
Most of the workers will be hired locally. The area is mainly known for producing livestock and levels of unemployment are high, especially for women. However, women will make up around 60% of this particular workforce, as it already does at the two existing UPM nurseries in western Uruguay.
Rey believes the new nursery will help to boost the region and to exemplify this commitment, he explains that a small training nursery is also being constructed to provide technical training to those members of the community interested in working at the site.
Completing the nursery’s staff are the management team, which is currently undergoing on-the-job training in the existing nurseries, and irrigation and electromechanics specialists, as well as forestry and agricultural technicians.
The nursery will add further technologies like metal-frame greenhouses with intelligent computerised temperature, humidity, water and fertilisation controls, biomass-based heating and a system that can recover surplus irrigation for reuse in the nursery itself without generating effluents.
“These technologies have a significant influence in the nursery’s construction budget, as the goal is to provide the cuttings with the best conditions so we can increase the 50% rooting rate to 60% or 70%. Ten years ago, it was barely a 20%,” says Rey.
The amount of plants that the nursery will supply , was defined in a master wood sourcing plan which takes into consideration the quantity of wood required by the pulp mill, its species mix and the desired fibre quality.
A eucalyptus seedling takes approximately 10 years to become a fully grown tree, so the rotation plan between planting and harvesting is key to ensuring that the new nursery will successfully cater to the needs of UPM’s new pulp mill. Once up and running, this nursery will exemplify the future of sustainable forest management in this forward-thinking country.