Guideline - Eucs and the Environment

7/31/2019 Guideline - Eucs and the Environment

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fired at the SPGS team. Since the SPGS often

recommends planting eucalypts where growers

have suitable sites, we believe that we have anobligation to ensure people understand the issues

better so they can make informed decisions, not

ones based on rumour and ignorance. Hence this

special feature on what is known in some countries

as the great Eucalyptus debate. You will be glad

to know that we do not need to reinvent the wheel

and start decades of research to prove the point: the

environmental aspects of planting eucalypts have

been scientifically studied in many other countries

(notably South Africa, India, Brazil and Australia).

Here we present a summary (in simple language) ofthe key issues and we hope it is a useful addition to

the debate.

Kalitunsi (as eucalypts are known in

Uganda) bring out mixed emotions in

people it seems. On the one hand, manysmall farmers grow them as cash crops for

fuelwood and poles whilst more commercial growers

are increasingly planting eucalypts since they can

produce a timber (or large pole) crop more quickly

than virtually any other species. Then on the other

hand we hear and read claims that eucalypts are

responsible for many environmental problems -

including excessive water use, depleting the soil of

its fertility, soil erosion - even global warming! It

appears to be difficult to have a balanced debate,

based not on hearsay but on fact.

Do they really use up so much water? and Do

eucalypts degrade the land?are common questions

SPGS PLANTATION GUIDELINE

No.6b EUCALYPTS & THE ENVIRONMENT


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SPGS PLANTATION GUIDELINE NO. 6b

2 EUCALYPTS & THE ENVIRONMENT

A landowner in western Uganda proudly showing his crop of E. grandis fuelwood ready to transport to a nearby tea estate. Without suchplantations, the nearby natural forests would disappear.

Eucalypts: An IntroductionEucalypts play an important role in the rural economies of manycountries - including Uganda - where they provide domestic andindustrial fuelwood, building and electricity poles, and of course,timber. In some countries, eucalypt plantations supply the rawmaterial for large scale wood-using industries: South Africawith some 525,000 hectares of eucalypts being a good example.Worldwide it is estimated that there are 15 million hectares ofeucalypt plantations (ca.1.8M in Africa) - dominated by justfour of the 500 or so Eucalyptus species - namely, E. grandis, E.camaldulensis, E. tereticornis and E. globulus.

Eucalypts are popular with both small and commercial growers

alike because of a number of attributes: they are well suited to growing in plantations; they can grow very fast if cultivated properly; they can provide a decent return on investment; they are adaptible to a wide range of sites; most species can be grown easily from seed; many species regrow (coppice) when cut; there have been huge gains made by breeding especially the

mass production of hybrid clones.

Eucalypts in UgandaEucalypts are a common feature in the Ugandan landscape. Manyrural households (with the exception of the drier eastern parts

of the country) have some eucalypt trees to provide poles andfirewood. The important tea industry concentrated in the westof Uganda, relies on eucalypt plantations (nearly all E. grandis) toprovide the fuelwood in order to dry the tea prior to export.Everwhere buildings are constructed using eucalypt scaffoldingpoles. Ugandas electricity supply company are desperate for largeeucalypt poles but often have to import them from elsewhere ata great cost. Ugandas timber using businesses are increasinglyusing eucalypt wood too and many of the remaining big trees arebeing harvested to meet this demand.

Thus in Uganda - as in many other countries - eucalypts areimportant. Clearly without them, there would be even more

natural forest cut down to provide alternatives to the productsdescribed earlier. There is another important aspect too: Ugandahas a timber crisis looming. When its remaining plantations havebeen harvested (in less than 5 years) it has a huge shortfall in

timber supply until the plantations planted over the past 5 yearsare ready for harvesting. These plantations are mostly pines thatwill not mature until around 20 years old. Only by planting fastgrown eucalypts can this worrying supply gap be plugged.

So...with all the current interest in growing eucalypts on both alarge and small scale in Uganda, and their undoubted value to theeconomy, why do they continue to receive bad press from somequarters? To answer this, let us delve a bit deeper into the claimsmade against eucalypts and see if they could be true.

E. grandis grows extremely well in the wetter parts of Uganda.

This 50-year old seed stand is in Fort Portal.


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EUCALYPTS & THE ENVIRONMENT 3

Claim 1: Excessive Water Consumption

It is often claimed that eucalypts have a high water demand

which leads to a reduction in downstream flow. Indeed, it is

hardly surprising that they have such a reputation since they

have been introduced into some countries (including Uganda)

to drain swamps for malaria control. Eucalypt plantations arealso used in Australia to deliberately lower water tables in

areas with high salinity.

In this regard, eucalypts are no different to any plants:

they require water

(and nutrients) to grow.

Eucalypts are very efficient

in terms of biomass

production (requiring only

one half to one third of

the water used by many

agricultural crops). Thefaster trees grow, however,

the more biomass they

accumulate and clearly, the

more water reserves will be

drawn on, no matter what

species.

Where water is plentiful,

this presents no problems;

where it is scarce, however,

eucalypts will compete for

available water and this

could lead to conflict.

Careful planning should

help alleviate any conflicts -

particularly by identifying

areas where eucalypt

plantations will not compete for water with other users.

2. Nutrient Depletion

In common with any crop, eucalypts require nutrients to

grow. Eucalypts are in fact very efficient users of available

resources (related to the often harsh environment where

they evolved in Australia) but clearly, their nutrient demand

will be high in order to sustain their very high yields when

cultivated intensively. Consequently it is normal practice

to apply fertilsers when planting eucalypts on a commercial

scale. This practice is no different from any other intensive

farming system.

3. Site Degredation

Eucalypts are sometimes blamed for increasing soil erosion.

Again here there is no evidence to single out eucalypts for

special criticism. More important than the species planted is

the erodibility of the soil, and the management of the crop.On sites that might be at risk of erosion (e.g. steep slopes and

sandy soils) there are management techniques that can be

adopted to minimise the damage.

4. Biodiversity Loss

There are claims that eucalypt plantations - along with other

exotic tree species - cause massive loss of biodiversity. This

depends on what vegetation was there beforehand: clearly a

monoculture does not have anything like the biodiversity of a

natural rain forest but this is an unfair comparison since suchplantations should not be established in such areas by clearing

intact natural forests. In Uganda, plantation development is

focused on degraded forest land and grassland: in this case

a eucalypt plantation may well reduce further biodiversity

loss.

5. Climate

Research has shown

that there is nothing

to distinguish

eucalypts fromplantations of any

other tree or from

different types

of native forests

in their effect on

rainfall or on other

regional climate

patterns.

Comment

Clearly there aredouble standards

being applied here:

commercial forestry

is often criticised

for practices that are

standard in agriculture, whether it be planting monocultures

of high yielding varieties or fertiliser application. Thus many

of the criticisms levelled against eucalypts could equally apply

to many other plantation crops.

In many places where there is the most noise against planting

eucalypts, the main contributors to the local environmentalproblems - namely, massive deforestation and poor farming

practices (compounded by global warming) - are conveniently

overlooked. In some degraded areas, eucalypts are the only

trees that survive and thus attract the blame for all the regions

environmental woes.

A private farmer in Kenya proudly shows off his clonal Eucalyptusplantation. He is growing this as a cash crop for poles and fuelwood

- assisted by the Gatsby Foundation - in a area of the country desperately

short of woody biomass.

For those keen to point the finger of blame for

droughts, global warming and poverty, eucalypts

should be seen as part of the solution rather than

the cause of such problems.


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4 EUCALYPTS & THE ENVIRONMENT

Conclusions and Guidelines

Ever increasing demands are being placed

on the worlds forest for both wood and non-

wood products. To compensate for this, tree

plantations have rapidly expanded and will

continue to do so, especially in regions where

growth rates can be high. Eucalypts are

important plantation species in many tropical

and sub-tropical countries for their ability to

produce high volumes of utilisable products in

a short time. In Uganda, eucalypts are valued

by both small farmers and larger commercial

growers and yet they have attracted criticism

from some quarters mostly for their alleged

impact on water, climate and soils.

Considerable scientific research has been carried

out on the subject in India, South Africa andAustralia - all countries where eucalypts are

important to the economy and the livelihoods

of many. The results show that eucalypts

are not as harmful as they have often been

portrayed but that the high water consumption

associated with high biomass yields, needs to

be considered, in an integrated way, with other

economic, socio-economic and environmental

factors. The challenge for planners and forest managers is

to design sustainable systems for growing eucalpyts which

minimise some of the adverse hydrological impacts whilst

maximising the economic and socio-economic benefits.

Suggested Practical Guidelines:

- better planning and more careful selection of sites

where eucalypts can be grown with little impact on the

envionment;

- restrict large scale planting where rainfall is marginal for

intensively grown eucalypts (

Guideline - Eucs and the Environment

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