DEN DROCLIMATIC PILOT STUDY I N ETHIOPIA

Report to t h e Overseas Development Administration

Research Scheme R4 198

K . R . B r i f f a

Climatic Research Unit, Norwich, U . K .

A. Russell-Smith

Iaiterrlational L ives tock Centre f o r Africa, A d d i s Ababa, E t h i o p i a

J u l y 1986

CLIMATIC RESEARCH UNIT School of Environmental Sciences

University of East Anglia Norwich, NR4 7TJ

t England

DEEFDROCLXMATXC PILOT STUDY IN ETHIOPIA

Report t o the Qverseas Development Administration

Research Scheme R419 8

Climatic Research U n i t , School of Enviromental Sciences,

University of East Anglia, Norwich N R 4 7TJ, U.K.

A, Rus gel l - S m i th

Forage Legume Agronomy Group, International Livestock Centre for Afr ica ,

P.O. Box 5689, Addis Ababa, Ethiopia

July 1986

Page

L i s t of Figures and Plates

1. Introduction and Statement of Aims

2. Sampling Programme

a) Overview

b) Deta i l s of Sites and Materials

c) Additional Material

3 . S a m p l e Preparation

4 . Results

a) Chronology Construction

b) Intra-annua l Growth Variations

5. Summary and Conclusions

6. Acknowledgements

LIST OP FIGWRITS W PIATES Page

Figure 1:

PLATE 1 :

PLATE 2:

PLATE 3 :

PLATE 4 :

F U T E 5:

PLATE 6:

PLATE 7 :

PLATE 8:

PLATE 9 :

Map showing the locat ion8 a t which coree were taken.

Podocarpus n r a c i l i o x from Mageda [Core ETH-0216BI.

Podocarpus nraci l ior from Magada [Core E T H 4 2 / 6 ~ 1 .

Juniperus procera from Menageaha [Cote ETH-O1/15A1,

Juniperus procera from Menagesha [Cote ETH-OL/lSAI.

Juniperus procera from Menageeha !Core ETH-01/17~].

Juniperus Drocera from Menageaha [Core E T H - 0 1 / 1 6 B ] .

Juniperus procera from Menagesha [Core ETH-Ol/l6A].

Juniperus vrocera from Menagesha [Core Em-011 17BJ.

Juniperus procera from Menagesha [Core E T H d l / l 6 A J ,

This report deacribes the r e su l t s of a p i l o t study o t the potent ia l

use8 of tree ring mater ia l for reconstructing c l imate and estimating

changes in forest produc t iv i ty in Ethiopia . This work is a c o l l a b o r a t i v e

research project between t h e C l i m a t i c Research U n i t (CRU), University of

East Anglia. Norwich and the International Livestock Centre for Africa

(UCA), Addis Ababa, Ethiopia, The specific objectives are t o aasess

prospects f o r :

1 ) reconstructing p a s t inter-annual cl imate f luc tua t ions , and

2 ) reconstructing long-term changes in fores t productivity.

The original work plan w a s as follows:

Two natural, undisturbed forest sites were t o be v i s i t e d in

March, 19 86, to c o l l e c t tree r i n g samples . Sampling was t o be

restr icted t o two species, J u n i ~ e r u s procera and Podocarpus gracilior.

Both genera have been used a u c c e s ~ f u l l y i n dendroc l imatic s tud ie s

elsewhere. Sample preparation, measurement and a n a l y s i s were to be

carr ied out using facilities in the CRU.

a) Overview

Dr Briffa v i s i t e d Ethiopia for three weeks from 11 t o 30 March 1986.

Details of the s a m p l i n g programme and extensive arrangements for f i e l d work

were made by Hr R u s s e l l - S m i t h CILCA) who accompanied Dr B r i f f a during moat

of t h i s work and a s s i s t e d in the coring and documentation, Mr Abdulkadir

Ahmed Samatar (ILCA) acted as driver and tranalator for the second week of

the sampling programme and aleo assisted with sampling. Throughout h i s

etay Dr B r i f f a was also accompanied by Mr Dechasa Jiru of the Foreetry

Research Centre, Minietry of Agriculture in Addis Ababa. Mr J i r u gave

invaluable assistance locating e i t e a , ident i fy ing species and sampling.

The sampl ing program arranged by Mr Russel l - S m i t h involved virxiting

e ight aites, considerably more than or ig ina l ly envisaged. Their locations

are shown i n Figure 1. Five of these are in Arusi province. Three of

theae f i v e are i n A s e l a (west of M E . C h i l a l o ) , and the other two are near

each other at Kuke and Dalele i n the Munessa S t a t e Forest. The three other

sitee are in the separate provinces of Sidamo, Bale and Shoa. Over 2000kms

were covered during this field work and 126 cores were eventual ly extracted

from 55 trees a t the 8 sites. These are almost exc luaive ly from trees of

the two species spec i f i ed in the o r i g i n a l work plan, i.e. Podoear~us

g r a c i l i o r and Juniperus procera. A s m a l l number of other indigenous

species and young exotics were a lso eampled. A brief descr ip t ion of the

sites and of the material sampled is given in the fo l lowing section.

Figure 1: Map showing the locations of the eight a i r e e (shown as triangles) a t which tree cores were taken. The dotted l i n e s a r e administrative region boundaries. h e s i tes are: 1. Asela (near Cadu l i v e s t o c k centre); 2. Dogha; 3. Welkese; 4 . Kuke; 5. D a l e l e ; 6. Hagada; 7. Bale National Park; 8.

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b) Details of Sites and M a t e r i a l s Sampled

Eight sites were sampled, Detai ls are given for each.

1. Site: Asela (near Cadu l i v e s t o c k centre), Arusi. Cored 12 March

19 86.

Lat, 7 ° 5 8 , ~ ' ~ , h n g . 3~"07.8'~, Alt. 2400m.

Main species: Podocarpus nracil ior.

A s s o c i a t e d species: Juniperus procera, Croton machro~tachvus, Olea

w e l w i t c h i i , Acacia abs in ica and Pygeum africanum.

Remarks: This site is a poor remnant of former Podocarpus forest.

Much of the area is open grass land which has been extensively c leared

for a g r i c u l t u r e and o n l y scattered trees exist. The sampled t r e e s are

on a west fac ing s l o p e of some 10 t o 15%. The site offered little if

any prospect for ampl ling reasonable numbers of trees. Only one

Podocarpus was aampled and two cores were extracted.

Several o t h e r trees were investigated, One core each from an Olea

welwitschii and a Py~eurn africanum were extracted. In a d d i t i o n to the

indigenous trees s a m p l e d , three cores were also taken from p l a n t a t i o n

trees of exot ic species. Two cores were sampled from a tree of Pinus

radiata and one from a Pinus patula . In a l l , seven cores from f i v e

trees of f i v e species were taken.

2 . Site: Dosha (3 km8 south of A s e l a ) , Arusi, Cored 1 2 March 1986.

Lat . 7 ' 5 5 . 8 ' ~ ~ Long. 3 9 ° 0 8 , 2 ' ~ , A l t . 2500m.

Main species: Juniperue procera

Associated s p e c i e s : as for Asela,

Remarks: S i x cores were taken from three trees, a l l Juniperus

procera, There was l i t t l e if any s lope . Trees aampled were chosen

from among iso l ated i n d i v idual a, many of which s h o w e d ev idence of

frequent, long e s t a b l i ~ h e d lopping, probably for fence b u i l d i n g and

fue l , Although the trees cored showed no s i g n s of interference, one

can have l i t t l e f a i t h w i t h regard t o obtaining untouched specimens.

3 . Site: Welkesa, Asusi. Cored P2 March 1986.

Lat. 7 ° 5 8 . 0 ' ~ , Long. 3 9 ' 0 8 . 0 ' ~ , Alt, 2200m.

Main species: Podocarpus nracilior,

Assoc ia ted species: as f o r Ase la ,

Rmarks: Two cores were sampled from one tree.

4. Site: Kuke, Munessa, Arusi. Cored 13 Match 19%.

Lat. 7 ' 2 9 , 7 ' ~ , Long. 38'52.0 '~, A l t . 2250m.

Main species: Pedocarpus gracilior.

Aseoc ia ted species: Croton macrostaehvs, Olea app. and Pv~eum

africanum.

Remarks: The site contains t a l l Podocarpus a t su f f i cent d e n s i t y t o

form a c losed canopy in many areas, However, t h i s site has been

logged over in recent decadee and frequent breaks in the high canopy

exiet . This has r e s u l t e d in co lon i sa t ion by Croton and much of t h e

area a l s o has th i ck shrub undergrowth making sampling d i f f i s u l t. The

general site slope of around 10 t o 152 g i v e s t h e site a northwest

facing aspect, Four corea were taken from two trees of Podocar~us

graci l ior , The Munessa forest has been aurveyed a s part of t h e South-

West E t h i o p i a Forest Inventory Project (Chaff e y , 197 8a).

5. S i t e : Dalele, Hunessa, Arusi. Cared 14 March 1986.

Lat. 7 ° 3 ~ . ~ ' ~ , Long. 38°52 .0"~ , A l t . 2280m.

Main species: Podocarpus nracilios.

Associated species: As for Kuke.

Remarks: Eleven cores were taken from f i v e trees of Podocarpus

ptac i l ios .

6 . Site: Magada Forest, Sidamo. Cored 18 March 1986.

t a t , 5 ' 3 0 . 5 ' ~ , Long. 38'15.5'~, A l t . 190Om.

Main s p e c ie s : Podocarpus grac i l ios.

Assoc ia ted species: Infrequent, mainly Olea, C e l t i ~ and Croton

species.

Remarks: This a i t e is a high Podocarpus foreat which forms a

genera l ly c lo sed upper storey canopy w i t h same broadleaf epecies are

present a t lower levels. The indiv idual Podocarpus are very large

and do not appear t o have been seriously a f f ec t ed by management or

f e l l i n g in t h e area sampled. T w e l v e cores were extracted from six

trees of Podocarpus ~ r a c i l i o r and two cores from one Cele is crauciana.

This area has been surveyed as part of the South-West Ethiopia Forest

Inventory Project (Chaffey, 1978bl.

7. Site: Bale National Park, Bale. Cored 20 and 21 March 1986,

Lat. 7"02 .5 '~ , Long, 3 9 ' 3 5 . 7 ' ~ , Alt.3400-3500m.

Main spec ie s : Juniperue rsrocera.

Assoc ia ted species : Very few, eome Hapenia abvasinica,

Remarks: T h i s site is on a steep w e s t facing slope of about 45 t o

50%. This s lope , together w i t h the a l t i t u d e meant that coring wag

d i f f i c u l t . However, because the site appeared ent ire ly undisturbed,

par t i cu lar effort was made to f ind r e l a t i v e l y large trees. Two days

were spent in t h e area and twenty-two corea were taken from e i g h t

trees of Juniperus pzocera. (See also (c) below.)

8 , Site: Suba, Menagesha Forest, Shoa. Cored 25 and 26 March 1986,

Lat. 9'02.0 '~ , Long.38'35.3 '~ , A l t . 2580~1,

Main s p e c i e s : Juniperus procera,

Aesociated species: Podocarpus ~racilior, Olea africana, AllophvLus

abv~einicua, Barbeya o leo ides and Cussonia Holstii.

Remarks: This site is part of a substantially closed, predominantly

Juniperus procera fores t . It is e s s e n t i a l l y undisturbed, though many

of the sampled trees had been marked for , but obviously subsequently

escaped f e l l i n g . This site was cored towards the end 05 the sampling

t r i p and was considered, on the basis of subjective inspection of site

end of preliminary cores, to be the most likely to provide usab le

mater ia l (from a dendrocl imatic viewpoint) . For t h i s reason,

considerable e f f o r t wap expended in s a m p l e c o l l e c t i o n . This produced

sixty-three cores from twenty-four trees of Juniperus procera. This

site has been described by F r i i s e t a l . (1982) and a more detailed

description of the f l o r i s t i c composition can be found there.

c ) Additional Material

In addi t ion t o the cores sampled w i t h an increment borer, th i r t een

cross-sections of t r e e trunks were obtained from f e l l e d s tock h e l d a t the

Wensa log yard at Eremo. These logs came from a s i t e c a l l e d Bubisa, near

Hharo in Bale and c l o s e t o s i t e 7 (see Figure l), They comprised ten

Juniperus procera and three Podocarpus nracilior. These s l i c e s were

selected by Dr Brif fa , thanks to the particular cooperation of Mr T e d l a

Assef a, the co-ordinator of the logging sect ion a t Wansa Woodworks. With

his h e l p and through the hard work of his men, hand-cut cross-sections were

obtained. These were transported back t o Add is Ababa where they were cut

into more manageable samples ( t w o pieces from bark to pith for each

sect ion) by the Wood U t i l i z a t i o n Research Department of the Forest Research

Department of the Ministry of Agriculture and a i r freighted by ILCA t o

Norwich,

It has no t y e t been possible to examine these larger sections of woad.

These were only recently received because of the time taken t o get Ministry

of Agriculture, Fisheries and Food import clearances. This material w i l l

need a large amount of preparatory work before it can be asaessed and

crosslnatching is l i k e l y t o be d i f f i c u l t and time consuming.

After sampling, the cores were mounted initially i n corrugated

cardboard for transportat ion back t o England. On arrivaL they s t i l l had a

h i g h water conten t and had t o be left t o dry for several weeks before

mounting i n grooved wooden mounting s t i c k s . A l l cores were then

provisional ly sanded and inspected .

As t h e number of cores taken on t h i s trip was q u i t e large and because

t i m e a v a i l a b l e for producing this report was l i m i t e d , it was necessary to

select a subset of cores f o r analysis.

I n d i v i d u a l s from a 1 l s i t e s were examined and s e l e c t i o n was baaed

s p e c i f i c a l l y on the apparent number of r i n g a and on how d i s c e r n i b l e and

uncomplicated the ring structure appeared t o be, Some cores from each

s p e c i e s s a m p l e d were se l ec ted . The se lec ted cores were then hand-sanded to

a high p o l i s h .

4. RESULTS

a) Chronology Construction

A t t h i s stage, i t haa not been p o s s i b l e t o produce any chronologies .

This is because t h e material c o l l e c t e d shows groweh complexities that make

cross-dating extreme1 y difficult. In parr icular

i) Several species do not show c lear ly discernible rings.

ii) Where rings are discernible , they ere u s u a l l y interspersed with

apparent regions of growth cessation which are not sufficiently

distinct t o be classed as ring boundaries,

iiir Where runs of genuine ring boundaries d i d occur ( L e , for some

parts of cores) these could not be matched p o s i t i v e l y over their

whole l ength even for cores from the same tree. Consequently, it

was not p o s s i b l e t o croes-match any material between trees.

These points preclude confident cross-dating at present, Cross-dating is

an essential prerequisite f o r forest product iv i ty and dendroclimatic

s t u d i e s , s ince i t is o n l y after success fu l croae-dating that one can be

sure that v i e i b l e rings are annual features.

During t h i s work it was apparent that, if any chronology (i.e. average

of a number of cross-dated r i n g r i d t h series) were t o be built, the time

available should be spent attempting t o crossdate o n l y a e l e c t e d core

series from sites with cores showing the largest number of clearly defined

rings, Consequently, only the mater ia l f rom Magada and Mensgesha was

examined in any d e t a i l . Podocarpus araci l ior and Juniperue procera were

the main species smpled at these sites,

I t was soon evident that Podocarpus is not s u i t a b l e for

dendrochronological studies in the areas sampled. This species does n o t

show consintently d i s c e r n i b l e rings. Many cores have some regions where

xings exiat, but these are rather indistinct and evident o n l y as regions of

Lighter or darker shading. The dark regions are v a r i a b l e in colour and

occas iona l ly appear t o indicate c lear growth cessation. An example is

shown in Plate 1. Plate 2 shows the more usual s i t u a t i o n for t h e

Bodocarrrua nraciliox corea examined. Indistinct bands of l ighter and

darker c e l l s which might represent annual rings are seen, but they do not

show sharp ring boundaries and do n o t a l l o w r i n g w i d t h meaeuremente t o be

made,

The major effort therefore has gone into examining t h e best Juniperus

material. This is the s e t of cores from Menagesha.

Menagesha - Juniperus procera

The sa l ient points describing t h i s , the most promising material, are

b e s t i l l u s t r a t e d by reference t o a ser iee of Plates. A l l the plates

discussed below show p o l i s h e d cores of Juniperus procera. Note that a 1 1

Plates are mounted so that the bark of the tree is t o the r i g h t end

conaequently growth is from left t o r igh t . The magnif icat ions shown do n o t

a l l o w fox expansion during printing. Thia produced a further magnification

factor of 5 .

Podocarpus nraci l ior from Magada [core E T I I - O P / ~ B ] . Magnified X 7.5,

PJATE 1: An example of apparent ring boundariee for Podocarvus that are

more distinct than usual. For a more typ ica l example, see Pla te 2 .

Podocarpus nraci l ior from Magada [Core ~ T I i - 0 2 / 6 ~ ] . Magnified X 7.5.

PIATB 2: An example showing the t y p i c a l l y indistinct "ring" boundaries for

thie species, These are evidenced merely by indistinct regions of darker

and l ighter shading.

Juniperus procera from Menagesha [Core E T R - O ~ / ~ SA], Magnified x 7.5.

P U T H 3 : This p l a t e shows discernible rings but closer inspection reveals

that the r ing boundary between r e l a t i v e ly csma l l thickened latewood ee l 1 s

and the larger thin-walled, earlywood c e l l e , i e often somewhat blurred,

The demarkation l ine [A] on the le f t of t h i e Plate i s quite eharp, That t o

the right [D] is less clear. It i e l i k e l y that there two boundaries

d e l i m i t one annual ring. However, a t t h i s stage erne eubjectivity is

involved in this judgement. In addition, there is some su~picion of minor

growth interuptioas within the main annual growth period I B + C ] which are

not distinct enough t o be considered true ring boundaries, '

Junipcrue vrocera from Menagesha ICore ETH-O1/ I S A ] . Magnified X 15.

PIATE 4: Thin Plate shows a region of growth suppression in which i t is

not p o e s i b l e t o distinguish ring boundaries w i t h any degree of certainty.

A similar region exists in the other core from this tree but not in cores

from other trees. This type of material can be ueed in chronology

development by omitting th i s section of the cores from th i s tree, provided

there i e sufficient we1 l - r e p l i c a t e d material from other trees t o be a b l e t o

cross-match on both s i d e s of the gap.

Juniverus Drocera from Menagerha [Core H T H 4 1 / 17A ] . Magnif i e d X 15.

PIATE 5: This Plate was chosen t o i l lus tra te one of tbe major d i f f i c u l t i e s

in crosedating this material, via . the problem of distinguishing between

true annual ring boundariea and fa l se , intra-annual boundariea. The run of

r e l a t i v e l y narrow rings i n the centre of the picture are reasonably clear,

But are they a l l annual? The three boundaries [A, B and C 1 are very thin.

I n fac t , they are s i n g l e rows of s l i g h t l y thickerrral l e d ce l l s , Are tbese

true annual ring boundaries or are they false ring boundariaet The d i l e m a

is made clearer when one looks at, what is at first glance, a t h i n ring t o

the right of the plate [D]. In fact, closer inspection indicatee that t h i s

is probably a f a loe ring and that it arises through a l a t e reour~ence of

growth after the secondary thickening of c e l l e has occurred and growth has

begun to slow down. False ring8 axe not an insurmountable problm, but

they can only be i d e n t i f i e d and e l iminated by m u l t i p l e compsrieons within

and between trees.

Juai~arua vrocexa from Henageshe [Core ETl€-Ol/l6~], Magnified x 15.

PLATE 6: Thia Plate is a good example which confirms the existence of

double ring8 in a t leaat ame of there corea. The three narrow ringa [A, B

and C1 in the picture are false rings. It i n not clear whether they

represent an i n i t i a l short period of growth occurring prior t o the major

onset of growth, or whether they ate l a t e periods of renewed growth

following the msjor period of radial expansion (as auggeeted for Plate 5).

Thie point is dirrcueaed in more detail later.

Juniverua Droeera from Meaageaha [core ~ ~ 1 1 4 1 / 1 6 A l . Hagnified X 15.

PIATE 7: Tbis shwa another problematic ring boundary [A]. This boundary

is not a8 distinct ara the other three boundaries shwa in thie Plate. The

c e l l s seem to become gradual lp mal ler both before and after the peak of

thickest amalleat ce l l s . This strongly suggests that boundary "A" is a

f a l e e ring. However, i f tbia i a true, then i t i a a very large false ring

and the to ta l width (between pointa [B] and [C]) would constitute an

unusual end aaomslously large ring.

Juniperus procera from Menagesha [Core ~TE-01117~1. Magnified X 15.

PIATE 8: This is included t o i l l u s t r a t e the occurrence of p a r t i a l or

disappearing rings, Such features are r e l a t i v e l y comnwn in the trees

sampled. Whether or not the ring between points [A] and [B] is a genuine

annual ring or a f a1 se ring is not clear, However, if it i8 an annual

ring, then it would be i d e n t i f i a b l e in some coxes, but miseing from others.

Part ia l rings l i k e this are not normally a serious problem provided that >

enough material is a v a i l a b l e t o identify missing rings by crosslnatcbing

between a large number of samples.

Junivcrus vrocera fram Henageshe [Core E T € I 4 1 / 1 6 A J . Magnified x 7.5.

P U T H 9 : This Plate is d e l i b e r a t e l y included ae the f ina t one in t h i s

report t o emphaeise the reel p o s s i b i l i t i e s that exist for overcoming the

problems discussed above. Such clear, unambiguously defined and variable

w i d t h ringa offer c lear potential for building a chronology a t t h i s site.

A very considerable effort, much more than is usual for tmperete or high-

latitude sites , would be required in order to overcome the problem

il lustrated in the earlier platen.

b) Intra-annual Growth Variations

More work is necessary t o explain and distinguish between f a l e e ringa

and true, but narrow annual r ings, This muet be done before a rea l attempt

can be made t o bui I d a chronology.

We suspect t h a t f a l s e rings arise because of the bimodal annual

r a i n f a l l distribution, rather than as a temperature effect. Temperatures

a t Menagesha (site a l t i t u d e of nearly 2600d are r e l a t i v e l y mild throughout

the year, Addis Ababa, a t 2410m, baa an annual mean of 16.8'~ w i t h the

lowest mean monthly temperature: around 14.9'~ (WHO, 197 1). This i m p 1 ies

that temperature would o n l y rarely be low enough t o cause a cessation of

tree growth and even then only for very short periods,

Bainf a 1 P in this region is general ly bimodal in i t s annual c y c l e .

Frequently, a short period of early rains peaking around April (at -100mm)

is f o l l o w e d by a r e l a t i v e l y dry period in May and June before rains again

increase t o a peak of around 240nmrs i n Auguet, November t o February are

again r e l a t i v e l y dry (Griffiths, 1972). This might suggest that an early

period of tree growth could precede the main growth period. However, the

gradation of c e l l s i z e suggests that the narrow rings follow, rather than

precede, the main rings. Thus, the seasons for these f a l s e rings, and for

the apparently large intra-annual fluctuations in growth rate are s t i l l

debateable.

Cores from e ight s i t e s of two main species, Podocar~ua araci l ior and

Juniperus procera have been collected,

I t has been es tab l i shed that Podocarpus nrac i l ior in t h i s area, for

all p r a c t i c a l purposes, i s unsu i tab le for dendrochsonological work.

Juniperus procera is more promising. It doea have d i s c e r n i b l e ringe,

but they vary in c l a r i t y . Double or false rings are present, as are

occasional areas of suppreesed growth, and p a r t i a l or missing rings are not

uncmon. Nevertheleas, this species is long- l ived and offers potential

for further work. This w i l l require good replication and the preparation

and analysis of many cores, Positive dat ing control ail l be dependent on

s a t i s f a c t o r i l y identifying annual as opposed to intra-annual ring

boundaries. Further work is required t o e s t a b l i s h the cause of the intra-

annua l growth f I trctuationa that produce f a1 ee ring boundaries and "double"

ringe. Analys i s of recent climate data and comparison of dry years with

narrow ring8 would be of value i n this regard, but the main (and

conventional) approach would be to carry out extensive cross-comparisons

between a large number of aampl-es. The work would c l e a r l y be time

consuming.

This project has produced potent ia l ly valuable material from two

sites, Menagesha in Shoa sdminietrative district and from the Bale National

Park. Only the Menagesha material has been examined, since most of the

Bale material is in the form of cro8~-sections, rather than cores, Cross-

sections require much more preparation time, but the a d d i t i o n a l material

mesna that the cross-matching problems described above may be'more easily

overcome.

Re l a t i o n s h i p s have now been estab l iehed between the CL imat ic Research

Unit and the International Livestock Centre for Africa and the Forestry

Research Centre in Ethiopia . A l l three institutions have expressed their

willingnees t o continue cooperation in further explor ing the potential of

t h i s and other material f o r dendrocl imatic and forest productivity work in

E t h i o p i a , Future sampling could be carried out by ILCA and FRC personnel.

However, much more material was col lected than o r i g i n a l l y envisaged and

a n a l y s i s of this material would be 0 5 higher priority than new sample

co l lec t ion , with one exception (see below). The material already examined

shows same p o t e n t i a l , but also more problems than one would have hoped to

see. A t least six man-months would be required to dec ide whether useful

resul t s can be obtained.

If, as we suspect, the observed falee and double rings are the resul t

of the bimodal rainfall distribution, then additional sampling in the areas

to the west of A d d i s Ababa (v iz , the weetern highlands of Ilubabor and

~ e f a r w o u l d be useful. Harberd (1975) p o i n t s out that r a i n f a l l in these

regiona i s d i s t i n c t l y unimodal. Juniperus proeera doe6 grow in these

regions although it becomes rarer as one moves further west (Chaffey,

1979). Sampling in theee areas could be carried o u t by our col laborators

in Ethiopia since we left coring equipment w i t h them s p e c i f i c a l l y for this

purpose. Mr Dechassa Jiru obtained s u f f i c i e n t f i e l d experience during h i s

time w i t h Dr Briffa t o be conf ident ly re l i ed o n t o c o l l e c t s u i t a b l e

material. If such material were to b e c o l l e c t e d , we would anticipate

requiring 4-6 man-months t o prepare and examine samples,

We are grateful far the cooperation and assistance of Dr B, T o t h i l l ,

Head of the Forage Legume Agronomy Group (FLAG), International Livestock

Centre for Africa, Addis Ababa, and of Hr Berhanu Bika, Head of Forestry

Research a t t h e Forestry Research Centre of the Ministry of Agriculture,

Addis Ababa. The i n v a l u a b l e contribution in the field of Ms Dechasa J i t u

of the Foreetry Research Centre is a l s o g r a t e f u l l y acknowledged, Thanka

for f i e l d aseistance are a l e o due t o Mr Abdulkadir A b e d Samatsr (FLAG,

ILCA). We are grateful to Mr Tedla Aasefa, the Coordinator of the Logging

Station of Wansa Uoodwosks and h i s men who provided croes-cut s l i c e s of

logs, We a l a o thank Mr Degafi S i s s a m , Head of Research on Working Property

and Trial Production a t the Wood U t i l i z a t i o n Research Centre (WUAR), Addia

Ababa, for having the cross-cut Log sections prepared for shipment t o t h e

United Kingdom.

Chaffep, D.&, 1978a: South-West E t h i o p i a Forest Inventory Project: An Inventory of Forest a t Kunessa and Shashemene. Project Report 29. ~THlO-O4-4/29 (7 8. ODA, Surbi ton.

Chaf fey , D&, 1978b: South-Vest E t h i o p i a Forest Inventory Project: An Inventory of Magada Forest. Project Report 28. ETH10-04-4/REP 2817 8. ODA, Surbiton.

Chaff ey, D.&, 1979 : South-Weat Ethiopia Forest Inventory Project: A reconnaisance inventory of foreet in s o u t h w e s t Ethiopia. Project Report 31. ~ ' 1 ~ - 0 4 - 6 / ~ ~ ~ - 3 1 / 7 9 , ODA, Surbiton,

F s i i s , 1. et al., 1982: S t u d i e s in the f lora and vege ta t ion of southwest Ethiopia. Opera Botanica 63, 1-70.

Gri f f i the , J.F., (Ed.) 1972: Climates of Africa. Volume 10. World Survey of Climatology. Elsevier, Amsterdam, 604 pp.

Hsrberd, R.T., 1975: Preliminary f i n d i n g s on a survey for t h e establishment of a master p l a n for the settlement of the south western provinces of Ethiopia. Addis Ababa: Re l i e f and Rehabilitation Commission.

World Meteoro logica l Organization, 197 1: C l imato l o g i c a l Normal S (cLINo) f o r CLIMAT and CLIMAT s h i p stations for the period 1932-60. WWOIQMM- No. 117, TP, 5 2 . W O , Geneva.