Natural Regeneration in Eucalyptus (5): surviving forestry fires.

Eucalyptus help protect soil against erosion after fire events

Or why setting the weeds on fire will just guarantee tree resurrection

Gustavo Iglesias Trabado
GIT Forestry Consulting - Consultoría y Servicios de Ingeniería Agroforestal - www.git-forestry.com - EUCALYPTOLOGICS

We have previously seen images of natural regeneration in E. delegatensis, E. obliqua, E. globulus, E. nitens, E. blakelyi, E. nicholii and E. gunnii in which regrowth was present from lignotuber or axillary buds after the removal af the aerial part of the trees. Today we will see one of the natural equivalents to coppice growth after timber harvest, which is vegetative regeneration after fire.

Fig. 1: Snow Gums regrowing after fire in the Victorian Alps (Australia)
(Photo courtesy of Phil in Sydney's Blog "Eucalypts In Habitat")

This response in different eucalypt species is the result of adaptation to changes in their natural Australian habitat during millenia, and particularly to different degrees of natural selection pressure caused by relatively frequent forestry fire events. After the loss of their aerial part by fire, only the most vigorous coppicer specimens become dominant trees and, if free from further fire damage in the short term, are able to produce flowers, cross pollinate and produce seed for a next generation. They compete among themselves, with other quick growing surrounding vegetation and also, if reproductively mature before being charred, with a new cohort of seedlings rapidly growing on short-term fertile soils rich in nutrients from ash.

Eucalyptus plantations after fire

In Eucalyptus forestry plantations overseas those species, provenances and races introduced from areas where evolution favoured vigorous coppicers show a similar behaviour. Even if the aerial part is totally killed, some months later new regrowth shows up in Eucalyptus trees and proves casualty rate is relatively low. Other types of tree covers, especially conifers, are a total loss instead. Intact eucalypt root systems are able to hold denuded soil from the adverse effect of erosion, which in areas of noticeable slope is the major catastrophic risk after a fire.

But managed plantations are normally grown in short rotation cycles and at quite close spacings, so peak seed production is not yet achieved even if reproductive maturity is reached, and tree crowns are small. Only overgrown trees and extramature stands do release seed in sufficient amounts for a noticeable colonisation of bare soils after fires but in most cases where coppice is vigorous enough these are quickly dominated by the fastest growing survivors, able to use available resources more efficiently with their already formed root systems, the same that can offer the only noticeable protection to soil.

Fig. 2: Example of vegetative regeneration 1 year after an unique forest fire event in an E. globulus plantation: +90% of charred stumps show new growth

However even these hard to kill plants have limits. Repeated fire events affecting young regrowth can greatly diminish their resilience and the number of survivor stumps declines some months later. With ability to coppice more than a dozen times, species like E. globulus cannot be erradicated by fire. But their weakening can reduce their ability to retain soil considerably. Repeated fire events anihilate other quick colonising vegetation and destroy the fertile layers of top soil, impoverishing the diversity of a subsequent vegetation cover, in case all soil is not removed earlier along the natural drainage lines and makes restoration impossible.

Fig. 3: Example of regeneration 1 year after two sucessive forest fire events in an E. globulus plantation: 50% of stumps show new growth. Note the very exposed soil compared to the previous.

Catastrophic events, forestry fires are the enemy of trees, animals and human beings. Against their pernicious effects Eucalyptus can offer some stubborn survival and some soil protection where other types of trees would be simply wiped out. However this help cannot be infinite. Well managed tree plantations, no matter the species, are not the main vegetation cover posing the higher risk of forest fires. But when catastrophe happens, some types of Eucalyptus offer their protection and can prevent further catastrophes as soil denudation and desertification.

Yet another irony, we had a trip from the myth of "Eucalyptus being the trees causing forest fires" to the fact of "Eucalyptus being the trees protecting soil after forest fires".

GIT's Eucalyptology Topics

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© 2007 Gustavo Iglesias Trabado. Please contact us if you want to use all or part of this text and photography elsewhere. We like to share, but we do not like rudeness.

Planting Eucalyptus: roots are not the problem

One of the controversial issues with Eucalyptus trees has to do with their root systems. Frequently exaggerated as a factor against their planting in gardens or urbanised areas as ornamental trees, menaces of doom to basements, pavements, drainages and other structures are widespread and even fantasy tales about their thirsty roots coming out of your kitchen tap are not that uncommon.

Difficult to debunk this myth with some real facts without digging up a bit. And that is exactly what Dr. Hailu Zerfu in collaboration with the Institute of Forest Ecology of the University of Vienna did in the highlands of Ethiopia, which, as you may have guessed, it is also Eucalyptus country.

Example of methodology to survey root spatial distribution and biomass and nutrient allocation in Eucalyptus fuelwood plantations established on deep heavy clay soils in Amhara (Ethiopia).

Spatial distribution of Eucalyptus root systems: summary of results

No doubt, some eucalypt species that reach big tree sizes when adult do have, as most of trees, a quite extensive root system. For forestry plantings and under the philosophy of sustainable forestry production, these root systems matter as both aboveground and belowground biomass immobilise carbon (so they are carbon sinks contributing to fight global warming) and also immobilise nutrients, which matters to the cycles of these in the forest.

For gardeners including eucalypts in their designs, studies like these can give small hints on why planting the wrong species of Eucalyptus right besides the walls of your house can pose a risk of future problems. But also hints of reasonably safe planting distances, which are not, as some propagate, dozens or hundreds of meters!

The problem then are not the Eucalyptus roots. The problem can arise, as usual, if planting the wrong species in the wrong place. Know your trees. And know your soils.

Eucalyptus timber: not just pulpwood

Complementary industrial lines with Eucalyptus wood in Northern Spain
Or how Eucalyptus globulus yields sawn timber, veneer, laminated wood, MDF board and furniture besides high quality cellulosic pulp

Gustavo Iglesias Trabado
GIT Forestry Consulting - Consultoría y Servicios de Ingeniería Agroforestal - www.git-forestry.com

EUCALYPTOLOGICS

Northern Spain, with a climate similar to Tasmania, shares also part of its landscape

Sourcing with Northern Portugal the majority of all Eucalyptus timber produced in Iberia

And the uses of Eucalyptus wood produced here are as diverse as the trees are


Photography of applied uses for Eucalyptus lumber courtesy of CIS-Madera. (Centro de Innovación y Servicios Tecnológicos de la Madera de Galicia)


Useful Links & Literature on Eucalyptus wood uses in Galicia

• EUROGLOBULUS: Manual de la Madera de Eucalipto Blanco / Eucalyptus globulus Timber Manual

• Nuevas aplicaciones de la madera de eucalipto / New industrial lines with eucalypt timber [PDF, in Spanish]

• Producción de Madera de Sierra de Alta Calidad con Eucalyptus globulus / Production of high quality Eucalyptus globulus lumber for sawmilling [PDF, in Spanish]

• Sistemas de Aserrado adecuados para Eucalyptus globulus Europeos afectados por tensiones de crecimiento / Saw-milling Systems for European Eucalyptus globulus affected by growth stresses [PDF, in Spanish]

• Una propuesta industrial de secado de madera de Eucalipto blanco (Eucalyptus globulus) de Galicia / An industrial proposal for Eucalyptus globulus wood kiln drying [PDF, in Spanish]

• Tecnologías de Secado de la Madera de Eucalipto/Eucalyptus Wood Drying Technologies

• Get "Eucalyptus: wood applications" catalogue for free! detailing finished works that use Eucalyptus globulus sawn timber, architectural wood based boards, furniture and structural elements for indoor and outdoor design. (PDF)

Not just Eucalyptus...

See also a very nice publication by CIS-Madeira on the most common type of timber grown in Northern Spain, the Maritime Pine (Pinus pinaster ssp. atlantica), and its industrial aplications.

ATLANWOOD - Industrial Aplications of Pinus pinaster

Other interesting links...

One to prevent our friend Fernando Sepliarsky, author of a nice paper entitled "Nuevos usos industriales de la madera de Eucalyptus globulus" [PDF] from asking again "so where is the Tasmanian Oak?" and finding no answer

TASMANIAN OAK: Roble de Tasmania in Galicia (NW Spain)

One to illustrate that the key concept of variability in Eucalyptus affects also the several types of eucalypt timber produced using cold hardy frost tolerant species in the Highlands of Northwestern Spain. Not everything is E. globulus.

Cold hardy Eucalyptus timber production in Galicia (NW Spain)


Want to know more?

Contact GIT Forestry Consulting - Eucalyptologics

GIT's Eucalyptology Topics

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© 2007-2008 Gustavo Iglesias Trabado. Please contact us if you want to use all or part of this text and photography elsewhere. We like to share, but we do not like rudeness.

Eucalyptus, not just timber (II): ornamental foliage production

One of the most striking aspects of genus Eucalyptus is their diversity. Sizes, shapes, colours, textures, fragrances. And multiple options for timber and non timber production, marketing and commercialization. Trees with bad press due to created interests, ignorance on their diversity frequently leads to firm opinion without solid basements.

Examples of Eucalyptus species suitable for foliage production in Galicia

Some years ago a certain Mr. Francisco Dans del Valle, forestry engineer, judged in 10 minutes a proposal for a Final Project from one of his college engineering students which involved identifying appropriate macro and microclimates for commercial cultivation of Eucalyptus trees able to yield annual non timber products under specially adapted forestry silvicultural regimes. Maybe judging on firm opinions based on limited data, the "impossible, so look for something else" veredict was not exactly very well received. Some years later, after trialling several dozen eucalypt species successfully in varied macro and microclimates in Northwestern Spain to assess cold hardiness both at nursery and in field conditions, working out the practicalities of what we foresters call "productive process engineering" the same way it had been done theoretically earlier, acquiring a proper know how and placing solid basements for a new pilar on Eucalyptus diversified production, we are able to say... "Paquito, lo que se siembra, se cosecha".

Wanna know how?

Complementary to timber oriented eucalypt experience GIT Forestry Consulting's team of Agronomic and Forestry Engineers has conducted horticultural trials in Northwestern Spain with select germplasm of over 30 Eucalyptus types having ornamental potential in both temperate humid Atlantic and Mediterranean climates, and has sorted out detailed individualised solutions to adapt successful productive process engineering to different industrial scale plant ornamental green foliage production schemes. An interesting range of potential products for floriculture markets has been obtained matching high quality standards.

This know how (what + when + how + why + how much) and our ability to organise training courses for your staff is now available via consulting agreement to wholesale or specialist floricultural producers interested in joining cooperative strategies for cultivation and commercialization.

And, to those ones growing eucalypts anywhere and thinking about the "what if's" of trying new things for your local conditions, be stubborn enough to not give up thinking "out of the box" for what others say and to not stop proving ignorance can be fixed.

If interested, we are happy to hear from you. Just fill the form and provide us with full contact details and a short description of your company's activity.

GIT's Eucalyptology Topics

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© 2007 Gustavo Iglesias Trabado. Please contact us if you want to use all or part of this text and photography elsewhere. We like to share, but we do not like rudeness.

Eucalyptus species identification: bark is not always enough

By their fruits ye shall know them
Small tips on Eucalyptus Identification

Gustavo Iglesias Trabado
GIT Forestry Consulting - Consultoría y Servicios de Ingeniería Agroforestal - www.git-forestry.com

EUCALYPTOLOGICS

Eucalyptus species determination is not just a matter of botanical interest. It can be quite important for its implications in regard to the different genetic pools (be them species, subspecies, provenances, or races) in cultivation. Important issues as cold hardiness (tolerance to winter frosts), growth rates (timber productivity) and physical and chemical properties of wood (timber quality) can depend on this variability, and hence be subject of forestry engineering.

Fig. 1: Two types of Ash ("Fraxinus wood-like") Eucalyptus: Tasmanian Oak

Telling Eucalyptus species apart can be difficult or confusing if differentiation criteria are based on a limited amount of variables. Bark type and characteristics can be one of the criteria for species identification, and can be considerably useful sometimes because some species are so strikingly different nothing else is needed. The chances of using bark successfully as "main criterium" are better for areas where eucalypts are introduced species, simply because the number of possibilities tends to be more limited than in a multispecific natural forest in Australia.

Fig 2: Examples of distinct bark characteristics in different Eucalyptus species

However, bark based identification can also be misleading. Pictured above (Fig. 1) you have two different types of eucalypts. If based on "bark only" criteria, maybe the first thought is they are two different species. But in fact, we are seeing two types of eucalypt belonging to the same species, but different gene pools. Both are Alpine Ash, a type of Tasmanian Oak (Roble de Tasmania).

Fig 3: Mature stand of rough barked Tasmanian Oak in the central plateau of Galicia, Spain

To the left (Fig. 1), the classical form, rough stringy bark in the lower portion of the main stem, clean withish bark in the upper portion and in the main branches. In mainland Southeastern Australia it has also received the vernacular name of "White Top". To the right, a variant, rough stringy persistant bark almost to the very top and on the main branches too. The latter type is restricted to natural habitats in Tasmania.

So, what the botanists say about this? Let's read Dean Nicolle:

• Eucalyptus delegatensis subsp. delegatensis (mainland Australia Alpine Ash) "Single stemmed tree 30 to 60 metres tall (...) Bark rough on the trunk up to 10 to 30 metres above ground level, moderately fissured and hard-fibrous, grey-brown; smooth above, ribbony, grey to pale grey over white"
  

• Eucalyptus delegatensis subsp. tasmaniensis (also known as E. tasmaniensis) "Single stemmed tree 20 to 90 metres tall (...) Bark rough over most of the entire trunk, moderately fissured and stringy-fibrous, grey brown to red-brown, smooth on branches, pale grey over cream"
  

An encouraging bark-based diagnosis indeed. But, back to the initial point, given the high chances of confusing both these types of eucalypt with others of the Ash type (E. obliqua, E. fastigata, E. regnans sometimes), and the extra options given by the possibility for some of these species to produce hybrid seed when grown in close spatial relationship, bark can help in some cases.

Fig. 4: Example of botanical sample gathering methodology for accurate Eucalyptus species identification (Click to enlarge)

But the most important information to work out what Eucalyptus we are seeing and defining geographically the original gene pools is to be sourced from comparison of flower buds and seed pods (fruit capsules) (Fig. 4) for the case of adult trees.

Fig. 5: Example of mature Eucalyptus specimen bearing flower buds and seed pods (capsules), essential organs for accurate Eucalyptus species identification. (Click image to enlarge).

Of course, once these trees are able to lure us into patient observation of their flower blooms and their seed bearing capsules in order to get them identified, little is left before you start collecting the later to obtain seed, and attempt to raise some plants.

Interesting links

Eucalyptus species identification (II): bark revisited

Fig. 6a: Example of "bark only" diagnosis misleading Eucalyptus species identification

Eucalyptus species identification (III): fruits & buds may be enough!

Fig. 6b: Example of "fruit & bud" diagnosis correctly leading to Eucalyptus species identification

Eucalyptus species identification (IV): fruits only may also work!

Fig. 6c: Example of "fruit only" diagnosis correctly leading to Eucalyptus species identification

Eucalyptus species identification (V): leaves may help!

Fig. 6d: Example of "leaf helped" diagnosis correctly leading to Eucalyptus species identification

Eucalyptus species identification (VI): hybrid mysteries uncovered!

Fig. 6e: Example of "compared traits" diagnosis correctly leading to Hybrid Eucalyptus identification

Eucalyptus Seed: Harvest it Right

Fig. 7: Different simultaneous stages of the reproductive cycle and eucalypt seed maturation process in a standing Snow Gum Eucalyptus tree.(Click to enlarge)

Eucalyptus Seed Collection: The Importance of Good Timing

Fig. 8: Maturation stages for eucalypt fruits collected on Corymbia calophylla trees in a single visit, showing some of the internal organs within Eucalyptus infrutescences in each phase. (Click to enlarge)

Eucalyptus from Seed: Some Key Concepts

Fig. 9: Examples of Eucalyptus seedling nursery stock for afforestation

Find a local expert to ID your Eucalyptus

If you have an unknown eucalypt around and you are able to collect and photograph samples of the key organs needed for identification, do not hesitate contacting GIT Forestry Consulting.

Contact GIT Forestry Consulting - Eucalyptologics

If you are in the USA and find it easier to post fresh samples to a local expert, you can also contact Dr. Matt Ritter, resident eucalypt hunter at the California Polytechnic State University.

GIT's Eucalyptology Topics

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© 2007 Gustavo Iglesias Trabado. Please contact us if you want to use all or part of this text and photography elsewhere. We like to share, but we do not like rudeness.