Eucalyptus depletes the the nutrients and moisture reserves of the soil and inhibits the  undergrowth due to allelopathic properties. Furthermore the decomposition of the dead plant parts is very slow which adversely affects the nutrient cycling. Owing to these adverse effects, Eucalyptus is often referred as " Ecological Terrorist". Please check these links and PDF attachments for more details.

https://www.researchgate.net/publication/257198237_Eucalyptus_invasions_in_riparian_forests_Effects_on_native_vegetation_community_diversity_stand_structure_and_composition

https://www.researchgate.net/publication/257931812_Allelopathic_effects_of_Eucalyptus_Eucalyptus_Camldulensis_L_on_germination_and_seedling_growth_of_wheat_Triticum_aestivum_L

http://www.hindawi.com/journals/ijfr/2013/463030/

http://www.ncbi.nlm.nih.gov/pubmed/19899483

Article Eucalyptus invasions in riparian forests: Effects on native ...

Article Allelopathic effects of Eucalyptus (Eucalyptus Camldulensis ...

Dear Antonio Lambe, I would like to point out the positive effects of Eucalyptus plantation on ecology and agricultural production. Rise in groundwater table followed by waterlogging and secondary soil salinization is a serious problem in canal-irrigated areas of arid and semi-arid regions. To combat this problem, an agroforestry model for biodrainage using Eucalyptus was tested in waterlogged fields with sandy loam soil in Haryana (northwest India) where 10% area (0.44 m ha) is waterlogged resulting in reduced crop yields and abandonment of agricultural lands.

In this model, four parallel strip-plantations of clonal Eucalyptus tereticornis were raised on four ridges constructed in 4.8 ha canal-irrigated waterlogged fields, at a density of 300 plants per ha. The groundwater table underneath the strip-plantations remained lower than that in the adjacent fields and the drawdown in groundwater table was 0.85 m in 3 years. The annual rate of transpiration by 240 surviving trees per ha was 268 mm per annum against the mean annual rainfall of 212 mm. These plantations generated 46.6 t per ha fresh biomass with benefit–cost ratio of 3.5 and also sequestered 15.5 t carbon per ha. Lowering of water table and  associated soil improvement by Eucalyptus plantations increased the wheat grain yield (in the interspace area) by 3.4 times and resulted in reclamation of waterlogged areas.

I suggest you to read the following articles for further information in the direction:

J. Ram et al. (2011) Biodrainage to combat waterlogging, increase farm productivity and sequester carbon in  canal command areas of northwest India. Current Science 100 (11):1673-1680.

S.K. Jena et al. (2016) Integrated Farming System and Biodrainage: Management of Waterlogged Area. Chapter 9. Pages 383-407 in Soil and Water Engineering: Principles and Applications of Modeling (Eds. B. Panigrahi and M.R. Goyal). Apple Academic Press, Inc.  

Thank you, Dilip, for the detailed response.  You noted "the positive effects of Eucalyptus plantation on ecology and agricultural production":

> Rise in groundwater table followed by waterlogging and secondary soil salinization is a serious problem in canal-irrigated areas of arid and semi-arid regions...

            What the positive effect on (non-human) ecology is of replacing what was once, presumably, a wetland, one of nature's richest habitats, with cropland is unclear.  But there is no uncertainty concerning the draining ability of Eucalyptus.  The tree's impressive thirst is well-known.  However, most gum plantation is not for this purpose.

> In this model, four parallel strip-plantations of clonal Eucalyptus tereticornis were raised on four ridges constructed in 4.8 ha canal-irrigated waterlogged fields, at a density of 300 plants per ha. The groundwater table underneath the strip-plantations remained lower than that in the adjacent fields and the drawdown in groundwater table was 0.85 m in 3 years.

            A striking testament to the tree's ability to remove groundwater.

> The annual rate of transpiration by 240 surviving trees per ha was 268 mm per annum against the mean annual rainfall of 212 mm.

            Again, impressive.

> These plantations generated 46.6 t per ha fresh biomass with benefit–cost ratio of 3.5 and also sequestered 15.5 t carbon per ha.

            Fine.  Could you explain what the biomass was used for, please?

> Lowering of water table and  associated soil improvement by Eucalyptus plantations increased the wheat grain yield (in the interspace area) by 3.4 times and resulted in reclamation of waterlogged areas.

            Fair enough.

> I suggest you to read the following articles for further information in the direction:

            I am grateful for your suggestions; but both deal largely with the drainage issue.

Dear Antonio, thanks for your pointed response to the inputs provided by me. I have already informed that Eucalyptus plantation grown for reclamation of waste/waterlogged land (by biodrainage) in the region generated 46.6 t per ha fresh biomass. 

Eucalyptus biomass has many economic uses. Their wood is used as timber, firewood and pulpwood. It is also used in a number of industries, from fence posts and charcoal to cellulose extraction for biofuels. Eucalyptus oil is readily steam distilled from the leaves and can be used for cleaning and as an industrial solvent, as an antiseptic, for deodorising, and in very small quantities in food supplements, especially sweets, cough drops, toothpaste and decongestants. It has insect repellent properties and is an active ingredient in some commercial mosquito repellents.

Yes, in semiarid and arid parts of northwest India, and in humid tropic coastal belts of India, Eucalyptus plantation is being successfully used for reclamation of land (by biodrainage) for agricultural production.  

Dear Antonio,

I Am a fervent supporter of eucalyptus cultivation both in integrated farm management and plantations,i also manage a eucalyptus for biological drainage for climate change mitigation and adaptation in my native country, Cameroon.LAST year, i attended a IUFRO eucalypt conference in SE China,it was a great experience.

Eucalyptus drains water, eucalyptus is an invasive species, all that is mere manipulation.The China eucalypt research center http:/chinaeuc.com/ is doing a marvellous scientific work.

ANTONIO EUCALYPTS ARE NOT THE PROBLEM, THE PROBLEM IS MAN.

beckline.

A debate going on in countries where Eucalypts are gradually becoming dominant in plantation programs; in some cases even replacing the natural (degraded) forests! Of course problem is NOT Eucalypts, but the decision of you how you are managing it! Some of the negative impacts (soil erosion, not support wildlife, allelopathy ....) on planting Eucalypts is also applicable for other species also, BUT blame always goes with it! My country officially ban the planting of Eucalypts but the farmers, small growers are planting it in their homesteads, marginal lands, social forestry because of its excellent survival, minimum care and early return (maximum productivity). Considering the situation, we (with my colleague) wrote a book titled "Eucalyptus Dilemma in Bangladesh" where we tried to include both the positive and negative impacts of Eucalyptus planting in Bangladesh. Finally Eucalyptus may be included in plantations not more than 20% in composition and mixed plantations with other species may diminish all the criticisms of Eucalypts that are mostly in debate! 

What makes eucalyptus plantations good or bad is the practitioner. If the practitioner plant it on proper place its good and if the practitioner planted it on improper places such as on farmland it might be bad. For one thing in mind to think is that eucalyptus is not invasive! For Ethiopian case eucalyptus has becoming cash tree contributing income for several of rural households. It is the main material for house construction and scaffolding in urban buildings. 

Antonio,

In the end, its simply a trade-off game and not about the Eucalyptus goodness or badness. Its also been cursed and praised in Africa depending on where you stand or what is important to you. For instance, If villagers are worried about fuel wood for their next meal, and Eucalyptus offer the most wood, then they will be less worried about planting them close to riparian zones or draining water catchments. And if you have an ecologist comfortable in an urban setting with plenty of electrical or gas energy (as most of us are), then the worry and complains will be on how the wetland ecosystem structure and functioning is affected. Thus, there is nothing for nothing.

My thanks to all for your recent comments.  Some thoughts follow.

Dilip provided a good list of Eucalyptus' many applications.  My NGO has planted globulus in barren Andean highlands to provide firewood for indigenous communities to reduce native Polylepis forest felling.  This was, however, no "reclamation of land" (or removal of wetland), only an attempt to mitigate a bad situation.

One might add its use, "with great care" as Danish researcher Thor Hjarsen has noted, in urgent erosion control.  And for those whose interests extend beyond utility and lucre gums can also be magnificent and beautiful - tropical E. deglupta with one of the world's most colourful trunks comes to mind.

"Fervent supporter", Beckline, is right that the tree is not invasive.  In Mediterranean conditions, at least, only a few seedlings appear.  But that the tree drains water is not "manipulation".  It is, as Dilip makes clear, plain fact.  If Beckline's unqualified effusiveness reflects a national attitude very different to Bangladesh's, I fear for his country's magnificent, rich, Rousseau-like forest.  Still, his statement about man being the problem is incontestable.  But it recalls American gun advocates' "Guns don't kill people.  People kill people."  The tree has its uses and its abuses.  Hence, as Mohammed, Zenebe and John suggest, it needs judgement and regulation.

Mohammed is also correct about on-going debate.  Some readers may be interested in the perspectives from one end of the spectrum in http://wrm.org.uy/books-and-briefings/ten-replies-to-ten-lies/ . 

Justin is definitely right about two compounding factors, the prior ravaging of sites, illustrated, and the homogenous planting that follows.  Unfortunately, the 20% maximum density in the mixed plantation that Mohammed advocates with the staggered and selective harvesting this implies will be far less profitable.  It is, though, the sort of standard that governments should impose at least in sensitive or protected areas.

Antonio

I just wish to add in discussion that Eucalyptus is not invasive species as you never see natural regeneration of eucalyptus in plantations. All are raised form seedling or clonal material brought from nursery? Now comes to utility being there is no better substitute for Eucalyptus in different regions of globe among indigenous species to meet fuel, pulpwood , timber and plywood need. In India 80 % paper industry depends on Ecalyptus pulp. Even Bmaboo plantations being fast in growth not adopted by farmers due cumbersome maintenance and harvest. Adaptability is remarkable from hill to coastal areas along all soil types. I don't think in Barring P.Juliflora any other species have such wide adaptability.

So its matter of resource mobilisation and biodiversity maintenance?  Ecology v/s economy. FSC also certifying as it producing sustainable resource even sometimes reclamation of degraded lands, bio drainage, salty area etc as mention earlier.

Finally it the question best we can balance eucalyptus use and plantations judiciously to to conserve native forests and meet wood demands of industries. 

I wholeheartedly endorse Justin's comments with one proviso: the issue, as Mohammed suggested earlier, need not be ecology vs. economy but may be ecology vs. short term economy vs. long term economy.

From bottom to top, the image below encapsulates the past, present and future under a get-rich-quick scheme.  Such a strategy so effectively reduces original flora and fauna that it undermines and eventually eliminates the biodiversity basis on which this Natura area was originally protected.

Eucalyptus has negative effects on the yields of intercrops when it was grown for wood

production.

It requires techniques such as canopy pruning, pollarding, thinning, root pruning by trenching and moving the first intercrop row farther from the tree-row for reducing the competition and to improve yields of intercrops in agroforesty. 

ijmr.net.in/download.php?filename=v0fC1ok8fCQKiyS.pdf&new...pdf

It was a surprise, Krishnan, to hear that intercropping was even contemplated among these voracious trees.  In some legislations Eucalyptus cannot be planted less than a certain distance from a neighbour's property for this very reason.

I have never seen intercropping practised in Portugal where the tree is used strictly for timber or pulp; nor as a shade tree for coffee or cacao.  Thank you for the information.

Very difficult to draw conclusion whether good or bad! But, it depends on the choice of species, species-site match, biological interference,and end uses. I ask a number of eucalyptus growers why they chose the species? Advantages- short rotation, fast growth,free from grazing animals and required less space. But long run this species needs vary careful and judicious plantation programs because exotics may not be the substitute for native species for long run. I have book "Eucalyptus Dilemma in Bangladesh" where I want to draw all the positive and negative effects. Thanks.

Thank you, Jose, for the recent advice in which you noted:

> I have spent most of my research time working on the water use of eucalypts in India. My conclusion is summarised:

            Very good.

> 1. Use the right species for your location, there are heavy water consumers among the eucalypt species.

            This suggests familiarity with many spp beyond deglupta which, I presume, is the predominant gum in south India.  The "right species" from the perspective of the Portuguese cellulose industry will be the one(s) that produce(s) most pulp in local Meditterranean conditions, dry, by European standards fairly hot (24-26°C) summers and variably-wet light-frosted winters.  And the spp selected are largely globulus and camaldulensis.  How do you rate these trees in this respect?

> 2. Plant with the right spacing. 1250 trees per hectare will be a good practice.

            8m² per tree, 3. Do not clear natural forests to plant eucalypts.

            Portugal has so little remaining natural forest left that doing so is, quite correctly, illegal.

> Since it will be a monocropping, the biodiversity is going to decrease, sometimes creating the wildlife to come out of the forests and create conflicts for farmers living nearby.

            Ah, if only we had such problems.

> If you follow the above rules, much of the environmental problems can be avoided.

            Again, my thanks.

The below mentioned researcher has many articles on eucalyptus for papermaking, specially the older articles. Happy new year.

https://www.researchgate.net/profile/Yehia_Fahmy

Dear followers of this blog, can you give your input to Eucalyptus-related concerns raised in following RG blog, please?: https://www.researchgate.net/post/Although_eucalyptus_is_not_eco-friendly_but_still_their_extensive_plantation_around_the_globe

Dear scholars

I have studied Eucalyptus globulus composition, and its diversifying properties. In areas where it is present in large quantity can be used to replace antibiotics. It is best plant in borders security due to its rapid growth and height. One other, very important current issue, is arsenic poisoning in ground water, which, directly affect pancreas and lead to diabetes. eucalyptus has quality to absorb arsenic and heavy metals. It can be grown on wastage water banks.It add cooling affects to environment due to high evaporation rate. On road side, It is used as a protective soft wall, where, it can save vehicles from high damages.

Negative aspects of Eucalyptus are that it absorb high water and depress other plants growth. Its plantation is discouraged now all over in Pakistan.

In conclusion, Eucalyptus has good medicinal properties. Its plantation should only be allowed after environmental department consultation.

Thank you to all

Regards

Assad Ullah

There is this saying that "there is nothing for nothing". In other words everything has a cost. Eucalyptus species aren't popular, or disliked, for nothing, more so in Africa. Despite their alleged negatives, the produce large volumes of wood for construction, fuelwood etc. which counts more and is better trade off to the rural communities. Of course there are ecosystem services that scientists may argue for or against the Eucalypts but rural communities ravaged by harsh economic realities, don't have the comfort to do so. Nonetheless where you have plenty of water, plant the glazers like E. grandis and where you have water stress conditions go for E. tereticornis or E. camaldulensis...

Thank you, John, for today's comments:

> There is this saying that "there is nothing for nothing". In other words everything has a cost.

        A rather utilitarian outlook but one that most of us endorse.

> Eucalyptus species aren't popular, or disliked, for nothing, more so in Africa.

        I don't doubt it even if WRI expects most of your continent to be less water-stressed than all others but South America.

> Despite their alleged negatives, the produce large volumes of wood for construction, fuelwood etc. which counts more and is better trade off to the rural communities.

        I'm unsure all rural communities would agree, but you are certainly correct about the tree's impressive productivity.

> Of course there are ecosystem services that scientists may argue for or against the Eucalypts but rural communities ravaged by harsh economic realities, don't have the comfort to do so.

         Their options are indeed more limited.

> Nonetheless where you have plenty of water, plant the glazers like E. grandis...

         "glazers"?  What about E. deglupta in tropical Africa?

> ...and where you have water stress conditions go for E. tereticornis or E. camaldulensis...

            Thank you for the advice.

Do you suggest Eucalyptus plantations in some region where water surface and rainfall store by flood water spreading? we have some cases in Iran in semi-arid region but we are going to change them to more drought resistance trees like Acacia. we believe that Eucalyptus are so heavy water consumers.

Thank you in advance

Thank you, Mehrdad, for your response. Some eucalyptus spp, e.g. robusta, have been used for draining water-logged areas if that's what you are looking for. On the other hand, as the Ramsar Convention has recognised, too many of the world's wetlands have already been lost. Acacias are, indeed, very drought-resistant, fix nitrogen, produce good firewood, gum arabic, etc. On the other hand, the tree can be much more invasive than eucalyptus. Bear this in mind and where possible, use natives rather than exotics.

Please find the attached file. What kind of meliorative procedures do you recommend?

Dear Antonio, many thanks for the topic you have chosen

Although when you hear “Eucalyptus”, you then remember “Australia”, other countries around the world have increasingly planted “Eucalyptus” – e.g. Iran specially Bandar Abbas, Zabol and Yazd cities and, rarely Fars province.

Up to now, we heard various aspects of usefulness from “Eucalyptus” trees, but their long roots have caused serious urban challenges. Recently, I saw a short video where roots of “Eucalyptus” tree has penetrated tens of meters into sewer pipelines. Please find the attached file. What kind of meliorative procedures do you recommend?

Reza, what is shown on that clip doesn't quite look like roots. Nonetheless, if they are indeed Eucalyptus roots the best meliorative thing to do is to avoid planting the trees very close to urban dwellings. Eucalyptus trees, especially Eucalyptus grandis, will grow large and develop massive roots that can break floors of buildings. They also bear huge branches that can easily snap off the tree and fall on roofs of nearby houses.

How this problem should be solved via reasonable Eco-friendly methods?

Thank you John for the response;

I agree with you and I'd like to say Eucalyptus planting has been now forbidden by most of Iranian urban infrastructure managers (prohibited trees). But, major concern is the existing trees.

I recently received a painful suggestion that these trees should be uprooted (logging) and replaced by other trees in the cities. I'm seeking for the answer to the question “How this problem should be solved via reasonable Eco-friendly methods?”

The ground is your as much as mine. Dear Jose, Thank you so much for taking the trouble to help me.I do appreciate it..

Role of Eucalyptus plantation in control waterlogging and salinity (Agric Water Management. 2020, 232: 106063) is briefed below:

Extensive experiences gained world over especially Australia to bring out the role the tree plantations play in controlling water vis-à-vis salt balances both at the farm and regional levels. In fact deep-rooted and profligate water user species like Eucalyptus provide for viable and productive alternatives for restoring hydrological balances and managing water-logging problems. However, their effectiveness for bio-drainage purposes is defined by factors like soil and climatic conditions, groundwater depth and its quality, fraction of area reforested, growth rates of species planted, their stocking, patterns and the geometries. However, with current lacunas of long time lags for groundwater response and high scales of planting, the impetus for reforestation can be generated only with additional benefits beyond on-and off-site salinity mitigation.

Thank you, Reza, for your interest in the subject and for the further comments your remarks and the striking video elicited.  You are right to associate eucalypts or "gums" with Australia although a handful, well almost two handsful including one with arguably the most multi-coloured trunk in nature, E. deglupta, are not from that country.

You are correct, also, as John Obiri confirms, that the tree is inappropriate near construction even if its main roots usually go down rather than across.  (Nevertheless it can be a hostile neighbour to other plants also; or it may not be.  This might surprise you as it did me.)  Pruning, as Jose suggests, can reduce falling branch damage but even with a cherry-picker this is no small task with large specimens.  Removing stumps is even more onerous.  Covering them with an opaque sheet or 4-5 cuts of new shoots over several months may kill the tree.

The salinity mitigation Mr Minhas cites, completely new to me, could make the tree valuable as we continue to raise sea-levels.

Antonio Lambe, thanks for your comment. I didn't know that the multi-coloured E. deglupta was not a native of Australia. Where is it from? I agree with you that Eucalypts can be hostile to neighbour plants. I believe the leaves may be having some allelopathic effects to seedlings of other plants. I don't know if anyone has looked into this phenomena.

Eucalyptus, by and large, is recognized as fast growing hardwood production tree around the world.

So we should plant suitable other trees near urban habitats if Eucalyptus does not gel with urban settings/ parameters.

Everything in world has a place and purpose. We can experiment and match the same.

Belated thanks, John Obiri, for the comments.  If you haven't looked up the answer yet, deglupta, also Rainbow or Mindanao gum, is not only from the Philippines but also from Indonesia and Papua New Guinea.  Like its much more numerous southern cousins it now grows in lots of warmer places but the Torrid Zone elicits most trunk colour.

There is also some web literature on allelopathy.  https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1439-037X.1997.tb00507.x is one example. It appears RG cannot handle hypertext.  Here is the link intended previously: https://appliedecologistsblog.com/2019/11/01/exotic-eucalypts-in-restoration-it-can-work/

Thanks also, Santosh Chaudhary, for your support and the idealistic, even brave "Everything in world has a place and purpose."  Is Covid telling is that there are too many of us; or that we shouldn't eat animals?

Antonio Lambe

Thanks for your appreciation. I learn lot from my husband who is a forester and tries to combine Mathematics and Forestry

Does anyone know of a review of problems with eucalyptus plantations in their native Australia? People who have worked with cloned monocultures in Brazil or southern China are shocked when they first see a native eucalypt forest in Australia, with odd-shaped trees and partly eaten leaves. But how do cloned monocultures do in Australia?

Australia has so many Eucalyptus species and sub-species and performance is also different from region to region!

I am a lawyer, not a scientist. However I specialize in environmental laws and therefore need to keep abreast of the sciences in my areas.

I have just found this conclusion in an article I found in my computer's folder on AIS (Alien Invasive Species) that I maintain for my research:

"The main drawbacks are its aggressive competition for resources with native flora, depletion of soil water, impoverishment of soil fertility under Eucalyptus, and finally its allelopathic property, which excludes and restricts germination and growth of other species and moreover the less recognized impact is the ignorance of indigenous species by local people for Eucalyptus species."

Source: Solomon, T.; Moon, H (2018), Expansion of Exotic Tree Species and Impacts on Management of the Indigenous Trees; Emphasis on Eucalyptus Species in Wolaita, South Ethiopia- A Review, International Journal of Research and Review, Vol.5; Issue: 1; January 2018, (15-20), available online: https://www.ijrrjournal.com/IJRR_Vol.5_Issue.1_Jan2018/IJRR004.pdf

Good or bad for whom? For the environment (e.g., acting as carbon sinks), for the biodiversity (e.g., depleting local biodiversity), for the entrepreneurs (e.g., representing short-term profits), for the local communities (e.g., cheap timber for construction)? Two additional aspects need to be considered: where and when. Plantations established in biodiverse areas have different impacts than those in poor, eroded areas. Also, the ecology vs. economy argument, mentioned before, has an intrinsic temporal dimension: even economic benefits in the short term can be highly diminished in the middle or long term, by the impoverishment of soils caused by the Eucalyptus.