Eucalyptus nitens. Shining Gum Eucalypt Highland Forests in Northwestern Iberia (I)
Eucalipto nitens. Bosques cultivados colinos de Eucalipto Brillante en el Noroeste Ibérico (I)


Following the Tasmanian Blue Gum (Eucalyptus globulus ssp. globulus) in our journey from sea level to 1700 meters elevation we walked in a transect across the foggy Eucalyptus belt in the Atlantic and Cantabrian coasts of Northwestern Iberia to reach a first stop in the inland plains and low hills of the Galician Highlands. Here E. globulus, affected by adverse winters, no longer prevails. A series of cold hardy Eucalyptus species starts to become an important element of rural landscape after recurring species trials for the last 50 years. Among these, several Tasmanian Oak species and several Eucalyptus species from higher elevations in the ranges of South Eastern Australia and the Tasmanian highlands. Today we stop for a while at one of the finest examples common these days. The Shining Gum tree.


This Eucalyptus tree can reach up to 70 meters height. Its juvenile leaves are tender, orbicular and opposite on aristate branchlets, and pungently fragrant. Adult leaves are alternate, long and falcate, flexible, setting up a high silvery crown when grown in plantations. Its columnar trunk can reach diameters of up to 1.8 meters and is covered by a stringy greyish bark when adult.

This forestry species was introduced to experimental arboreta in the Iberian Peninsula by the 1960's. Its cultivation has become generalised in inland Galicia and the Cantabrian Coast since 1990 onwards due to its good cold hardiness (resisting down to -11ºC and more than 100 frost events per year) and its excellent growth rates, becoming one of the preferred alternative species to E. globulus for inland areas or above 400 meters above sea level. It has good potential as a resource for cellulosic pulp altough its pulping properties are inferior to E. globulus and this makes it less favoured by local pulp mills. It can find applications for board production, and with a proper silvicultural management aimed to obtain big diameters of clearwood at final harvest, also reasonalbly good prospects for solid wood production (lumber for sawmilling or veneer). Due to its high growth rates is also a candidate species for biomass production targeted to green energy generation.

Its natural habitat are highlands in Central Victoria and some foothills of the Great Dividing Range in New South Wales (Australia). Nowadays the preferred seed provenances for afforestation in Spain are Central Victoria although there are clear examples of good survival and excellent growth in plantations cultivated with seed provenances from Southern New South Wales.

In the Iberian Northwest this species currently reaches annual increments in the range of 30 to 35 cubic meters of wood per hectare and year, being the common productivity around 20 to 25. It is, among forestry species cultivated in Europe, the fastest growing tree for afforestation in elevations ranging from 400 to 800 meters. On exceptional very high quality sites it has reached mean annual increments (MAI) in the close to 50 m3/ha/year, but this is unfortunately not the norm, altough average MAI's could be increased by using genetically improved seed and refining silvicultural practice, in particular early competition from weeds during the first years. Sometimes these potential improvements are not cost effective.

Widely cultivated in Chile, Tasmania and Victoria (Australia), Northern Spain and Portugal, New Zealand and South Africa, the Shining Gum is becoming an emerging species in the "top ten" of worldwide cultivated Eucalyptus and one of the interesting cold hardy species for temperate humid climates. Other cold hardy species are also promising, in particular for biomass/bioenergy production.


Photo 1 (left): 60 month old saplings of Eucalyptus nitens in a pulpwood plantation growing at 600 meters height in the Highlands of Galicia (Northwestern Spain). They have reached 11 meters height as average even with a poor understorey control.


We will make a first stop in a good example of multifunctional forestry. This Finca de Monte of over 250 hectares on hilly terrain and poor soils was previously treeless and considered marginal for highly productive forestry investments for some decades. However things have changed in the last years. The upper hills in this area, battered by constant wind all year long, have become a "hot spot" for new industrial opportunities. The era of turbines has arrived. Windfarms have become a major investment as energy markets worldwide push towards a more sustainable strategy. Up the hills here, as in other parts of Northwestern Iberia, windmill plantations progress as the target of increasing production of environmentally friendly green energy is accomplished.

In addition, down the hill from these range tops, soils of thin depth and rocky abundance no longer stay treeless. Here, where native broadleaved species cannot be grown at all and where most conifers would have important trouble for survival and big impedements for reasonable growth rates, the ubiquitous Eucalyptus prevails.

Photo 2: 100 hectare ongoing afforestation at 800 m elevation. Multiple use includes simultaneous timber polyculture, windfarms and extensive horse, sheep and cattle grazing

Reasonably big landholdings in Northwestern Iberia are normally part of the "commonlands", a particularly interesting formula for land tenure that assigns non agricultural land to the inhabitants of each parish as a whole. Traditional uses for these lands ranged from fuelwood for domestic use (as long as there was a suitable forestry resource already established) to biomass harvest for organic fertiliser production. Extensive grazing was widespread, using rustic species as "feral" horse and cow in heathlands or sheep in natural pastures. Rural exodus and structural socioeconomic evolution have made some of these uses decline with time. Only new approaches can mantain some of these at the same time new uses are simultaneously implemented.

Photo 3: Rocky soils of limited depth force the planting of frugal forestry species able to survive on acidic environments. Only conifers and eucalypts can thrive here.
Annual rainfall exceeding 1000 mm plus occasional winter snowfalls make moisture availability a minor problem except in the driest months of summer. Boggy terrain pockets are frequent and scattered among rocky areas. Only frugal tree species can take advantage of the situation and transform the limited available resources into useful timber where heath and gorse were the dominant (and very common) vegetation cover before, spreading forest fire risk and subsequent soil erosion risk considerably. Heavy machinery is needed to work in this type of terrain, but good timing and skilled work can manage to start the transformation of a treeless environment into a cultivated woodland.

Photo 4 (left): 52 months after planting, Eucalyptus nitens clearly outgrows Pinus, typical timber crop in this area. A similar result could be obtained with other cold hardy Eucalyptus species suitable for this environment.

Photo 5 (right): Fast growth means quick opening of temporarily fenced planted areas to understorey grazing , which is beneficial for extensive horse and cattle production, beneficial to reduce competence between understorey and tree crop to favour higher growth rates, and preventive of forest fire catastrophes.


Good matching of forestry species and cultivation sites, proper planting methodologies and the use of high quality seedling stock result in acceptable survival rates in the first years until the new timber plantation is fully established. In sites like the pictured one several alternatives soon arise for silvicultural management. Best soil pockets assuring a regular growth and acceptable timber yield can be managed for multiproduct log obtention. This, for the case of Eucalyptus nitens, requires early assessment and timely operations of low pruning on yet alive branches to reduce knotty cores and increase the yield of high value lumber. In addition, properly scheduled thining operations that reduce stocking per hectare must be implemented, creating a more open landscape, favouring higher annual grazing yield and favouring bigger diameters in remaining trees in order to grow fat logs.

Appropriate Forestry Engineering will develop suitable Management Plans for established timber and non timber resources as the ones previously mentioned. Proper and effective spatial and temporal distribution of tasks, materials and machinery necessary for tree planting, grazing according to a rotational schedule, fencing, implementation of silvicultural maintenance operations on tree saplings and adult trees, regular timber inventory , timber harvest and haulage and reafforestation operations do guarantee that such a multifunctional agroforestry resource can persist in time and space and yield economic, ecological and social benefits for rural communities in the future to come. Sustainable production is the first stone for the building of sustainable forestry.


Much of the total acreage occupied by Eucalyptus nitens in Northwestern Iberia is composed of a mixture of small plantings (1 to 2 hectares as average size) embedded in agricultural or ex agricultural landscapes. Speculative plantings done by private small landowners were boosted by impressive and easily visible growth rates elsewhere and by high (by then) market values for Eucalyptus timber (E. globulus) without much consideration for supply chain structure or scale economies. These plantations are normally unmanaged following regimes of minimal silviculture, sometimes planted at excessive stockage per hectare. Future financial viability of much of the small sized investments is a very concerning issue, and should make small investors think it twice before deciding what type of production (log size and log quality parameters) are they aiming to by planting this species in small woodlots.

Photo 6 (left): Commercially viable agroforestry plantations above 700 m elevation in exposed terrain can act as windbreak and protect grazing sites. Even if block size is relatively small, well planned simultaneous plantings make future simultaneous operations cost effective and will tend to increase the average value of each harvested log by reducing operational tree harvest costs.

Photo 7 (right): Small patches of mixed tree planting as buffer zones between agricultural land and hunting reserves. Overal plot size is too small for effective management and viable low unitary value commercial timber growing in the long term.


Photo 8 (left): Fast growing Eucalyptus agroforestry plantations above 650 m elevation subject to organic tree farming schemes can recycle urban sewage sediments, subproducts of biomass cofiring as ashes, or organic fertiliser subproducts of cattle and pig farms if these are properly treated and applied during tree crop production cycles.

Photo 9 (right): Timber crops on suitable abandoned intensive agricultural lands can act as windbreak blocks for remaining agricultural crops, provide shelter to cattle managed in extensive grazing systems both against summer heat and winter gales and contribute to diminish forest fire risks. High value logs could be obtained if proper silvicultural regimes targeted to simultaneous multiproduction of biomass, pulpwood and solid wood are implemented. Cold hardy Eucalyptus of several species can be good alternative choices for such production systems.



One often reads about the ecological risks of growing fast growing tree species, and especially eucalypts. Dooming predictions of depleted watertables and soil nutrient pools are certainly concerning. Forestry Engineers and Eucalyptus growers are often in the very edge of this conflict wondering why everyone talks about the trees without seeing the forests, but are also well able to see that many times people preaching certain ideas can know a lot about theoretical science and/or propaganda, but not too much about real tree growing.

Experience has proven us that a neutral approach is usually the wisest. The right crop (tree crop or not) in the right place (timberlands or not) grown the right way (organically or not) and managed correctly (technically or not) does pose as little environmental risk as native woodland reserves or traditional agricultural and farming systems. And it is able to provide us all with a huge range of products, services and positive externalities. In the particular case of Eucalyptus woodlands, the potential for yields of products (timber of several types and properties suitable for several industrial transformations, essential oils for pharmacy and cosmethics, woody biomass for energy generation), yields of services (herbaceous biomass for extensive or intensive grazing aiding animal production, habitat for controlled populations of animals suitable for hunting, receiver areas of organic waste from varied sources that becomes a subproduct and aids friendly fertilising) or yields of positive externalities (oxygen production, carbon sequestration, soil salinity control, woodland recreation possibilities) can be so impressive if things are done properly that balancing all this against some not always present environmental impacts gives a quite clear conclusion.

Properly managed Eucalyptus woodlands become one important piece of sustainable industrial timber production at once they contribute to sustainable forestry and sustainable primary resource exploitation. They can peacefully co-exist with any other land use type. This, of course, does not mean we do not need timberlands of other types, pristine native woodlands and native ecosystem reserves and coexisting agricultural and animal productions. But above all it means that what we need the most is stable rural communities as wardens of all this heritage for future generations.



Photo 10a (up left): Example of the quick evolution of a mixed Eucalyptus plantation after final harvest of the first timber crop of Eucalyptus nitens carried on at age 9 years over trees 25 meters high. Immediately after timber felling and extraction of debarked-on-site useful logs, available non woody biomass (bark, branches and leaves) is thinly crushed and used as organic fertiliser for the new afforestation. This step minimises overall nurient loss by returning a major percent of total macro and micronutrients stored in biomass (majority of this is stored exactly in photosynthetic tissues) to the soil. In the background, a timber alley of a slower growing Eucalyptus macarthurii awaiting harvest in the short term.

Photo 10b (bottom left): Just few weeks later small seedlings of Eucalyptus nitens were planted on a well prepared terrain, aided by extra fertiliser that balances soil nutritional status applied on planting spots, have reached increments of up to 1 meter height in 25 weeks post planting and have become well established in abundance of light, soil moisture and available nutrients. This almost organic tree farming crop will grow up to 8 meters height in the next two growing seasons, and a second harvest cycle of Eucalyptus nitens will be ready in a relatively short timeframe.





© 2007 Gustavo Iglesias Trabado / GIT Forestry Consulting - Consultoría y Servicios de Ingeniería Agroforestal - EUCALYPTOLOGICS