Status of the Bankouale Palm, Livistona carinensis (Chiov.) Dransf. et Uhl, in Djibouti


Henry Ford* and Clive Bealey**


* 77 Great Pulteney St., Bath BA2 4D ( for correspondence); ** English Nature, 1 Southampton Road, Lyndhurst, Hampshire, SO43 7BU



Introduction


The Bankouale Palm is the only member of the genus Livistona found in Africa and it is found in three areas: the Yemen, Somalia, and Djibouti. It is currently classed as 'vulnerable' in the IUCN/WCMC World List of Threatened Trees (1998). It is a statuesque fan palm growing to a height of 25 m with a grey brown trunk somewhat enlarged at the base and bearing some slight leaf scars (figs. 1, 2). The crown bears up to 40 stiff fan leaves on armed petioles over 1 m long. Inflorescences are axillary and may be 2m in length with hundreds of creamy yellow flowers. The fruits are hard and pea-like (Monod 1955). It grows in or by water. Water is not only crucial for germination, but it also seems crucial for establishment as young palms (fig 2) are always found where the ground is wet, though the adults may live in areas now quite dry. It is restricted in its distribution to springs, oases and wadis. Both in the Yemen and in Djibouti the Bankouale Palm is associated with the Date Palm, Phoenix caespitosa (Lebrun et al 1989, Welch and Welch 1998).


Fig 1: Livistonia carinensis grove at Didinto, Agorogouba. This site, at a spring (note the water pipe crossing the wadi) shows a range of heightsof adults (and therefore age), rosettes (to the left of the site) and the associated Phoenix caespitosa


Fig 2: The base of adolescent Livistonia carinensis showing leaf scars.


Fig 3: Rosette of Livistonia carinensis showing armed petioles.




Growth rates of adults have been measured in the field over a 13 year period (Welch and Welch 1998), and vary from between 17 and 33 cms per year, and it has been estimated that a 16.9 m palm was about 93 years old. With heights of maximum of 25 m, the oldest palms would be at most 150 years old. The growth of rosettes was reported to have been more variable (Welch and Welch, 1998).


The status of the populations in the Yemen and Somalia are uncertain. It has been reported that in Somalia the population may be less 38 trees (Thulin, M., in Welch and Welch, 1998) and there is evidence that the population in the Yemen is under threat from cutting (in Welch and Welch, 1998), where, as well as a substantial population of 1340 plants, they reported over 1800 stumps from cutting. The status of the palm in its stronghold of Djibouti has been investigated several times between 1985 and 1998 (Welch and Welch 1998) and the reports show a steady decline in numbers. This study was undertaken to determine the current status of the populations in Djibouti.


Over half of the palms are reported to be in mature, even-aged stands. This has implications for the future survival of the species. Firstly, it can be inferred that not only is establishment rare but that it occurs in singular events. The Welch's estimated that there has been little or no establishment during the last 60 years, except for a number of rosettes in Bankouale established during the 1990s. Secondly, this portion of the population is likely to senesce and die in a short period of time, with catastrophic results for the future survival of the species, removing the majority of the reproducing adults in a short period of time with all the consequences of the reduction of the gene pool that this will entail.


The Welchs reported several threats to the survival of this palm. The creation of gardens in the palm's favoured habitat has resulted in habitat loss for establishment. This creation may have resulted in the removal of adults, though there is no evidence of recent removal of living trees. However, when young, the palm retains its old leaves and forms a substantial bush and may be an obstacle to the gardeners. More insidiously, the establishments of these gardens will result in a change of hydrology both locally, particularly affecting the rosette stage, and over a wider area. These effects are not understood. Cattle and goat grazing is universal, and the young leaves are palatable and certainly seedlings will be quickly removed. The final threat is that of flash floods. It is known that these sweep away seedlings on a regular basis, and adults in more catastrophic events (Abdoulmalik, in Welch and Welch, 1998).


As part of a wider study of the wildlife of Djibouti Welch and Welch (1998) produced a comprehensive report with recommendations. They suggest that the palm was everywhere in a slow decline and that because of a lack of regeneration in the major sites, its status should be upgraded form vulnerable to critical. In this study we report the current status of the major sites of this palm around Bankouale and Ditilou.


Results and Discussion


Livistona carinensis is extremely limited in its worldwide distribution (Table 1 ). Welch and Welch (1998) report that the populations in Somalia and the Yemen were under threat and the population in Djibouti slowly declining. Whilst the population in the Yemen was 1357 individuals, they reported that there were over 1800 cut stumps in the main population and over 100 in the second population. They report that is seems likely that the majority of trees have been cut down within the last 20 years and that the trees were being felled.




Table 1: Status of the Bankouale palm (Livistonia carinensis) worldwide in 1998 (Welch and Welch, 1998)



Djibouti

Somalia

Yemen

Total

Adults 1998

351

38

1357

1753

Excent of occurrence (km²)

100

1600

1050

2750

Area of occupancy (km²)

20

6

12

38

Number of Sites

9

3

3

15

Rate of Decline

23-30% in 13 years

51% in 10 years

59% in 10-20 years



Table 2 illustrates the decline in some sites in Djibouti to from 1985 to 1998, and Table 3 shows the population status in those sites in Djibouti that were surveyed in February 2004. There was a 26% decline in adults between 1985 and 1998. In Bankouale, between 1985 and 2004 there was a 37% decline in adults, and where measurable elsewhere, a 26% decline in adults in the same period.


Table 2: Numbers of Adults(A), Juveniles (J) , Rosettes (R) and the Total number of individuals of Livistonia carinensis in sites around the Foret de Dai, Djibouti, between 1985 and 1998.(Welch and Welch, 1998)



1985

1987

1998



A

J

R

T

A

J

R

T

A

J

R

T

Randa

1

1

0

0

1





1

0

0

1


2

2

0

0

2





1

0

0

1


3

2

0

0

2





0

0

0

0


4

7

2

3

12





7

4

35

46


5

2

0

0

2





1

0

0

1


6

9

0

4

13





7

0

6

13


7

3

0

0

3





2

0

0

2

Subtotal


26

2

7

35





19

4

41

64

Ribta (upper)

1

30

0

0

30





29

0

0

29

Ribta (lower)

2









7

0

0

7

Subtotal










36

0

0

36

Toha

1





14

0

20

34

12

0

0

12


2





1

0

0

1

1

0

0

1

Wadi Eouali

1

1

0

0

1









2

10

0

0

10










3

1

0

0

1









4

1

0

0

1










5

4

0

0

4










6

1

0

0

1










Table 3. Numbers of Adults(A), Juveniles (J) , Rosettes (R) and the Total number of individuals of Livistonia carinensis in sites around the Foret de Dai, Djibouti, between 1985 and 2004.




1985

87

1990

1998

2004



A

J

R

T

A

A

J

R

T

A

J

R

T

A

J

R

T

Bankouale

1

32

1

0

33






19

0

12

32

17

0

10

27


2

16

4

0

20






11

2

41

54

11

1

2

14


3

6

1

0

7






0

0

0

0

0

0

0

0


4

0

3

0

3






0

1

0

1

1

0

0

1


5

1

0

0

1






0

0

0

0

0

0

0

0


6

13

0

0

13






10

0

0

10

8

0

0

8


7

15

0

0

15






9

0

0

9

7

0

0

7


8

65

0

0

65






48

0

0

48

42

0

0

42


9

19

0

0

19






14

0

0

14

13

0

0

13


10

5

0

0

5






4

0

0

4

4

0

0

4


11

34

0

76

110






29

0

50

79

28

0

0

28


12

1

0

0

1






0

0

0

0

0

0

0

0


13

1

0

0

1






1

0

0

1

0

0

0

0


15

3

0

0

3






0

0

0

0

0

0

0

0


16














0

6

0

6

Satabou,Bankouale

1,14

12

0

19

31










8

2

6

16

Subtotal


223

9

95

327






145

3

103

252

139

9

18

166

Satabou

1

12

0

19

31






9

2

2

13

8

2

6

16

*

2










6

0

4

10

13

0

3

16

*

3










9

0

23

32

8

0

0

8

*

4










2

0

0

2

2

0

0

2

Subtotal











26



57

31

2

9

42

Disay


39

0

2

41






27

6

26

59

25

4

18

47

*alternative nos!















23

20

25

68

Wêr

51

2

15

68






48

7

22

77

42

2

6

50

Ditilou















11

0

0

11
















1

0

0

1

Agorogouba

1






12

3

16

31

12

3

18

33

12

0

12

25


2






13

0

0

13

10

0

0

10

11

1

1

13


3






2

0

0

2

2

0

1

3

1

0

0

1


4






1

0

0

1

1

0

0

1

0

0

0

0




















Note: * : Satabou sites 2,3 and 4 were first visited in 1999.




Population Structure and Regeneration


The population structure of most of the populations appears to be heavily biased towards mature individuals with few young (fig 4). This is typical of the age structure of populations where the population is fully stocked in the first year of recruitment resulting in an even aged stand with “doomed” juveniles (Harper, 1977). However the population reduction is clearly seen in fig 5 which illustrates the decline in adults between 1985 and 2004, without any overall compensating increase in juveniles or rosettes.





Fig 4 Life history class structure of all poplations visited in 2004







Fig 5. Life history class structures of populations visited in 1985, 1998, and 2005




Regeneration is apparent in most populations observed though not in all sub-populations.


Seedlings:

Welch and Welch (1998) report abundant seedlings in several sites, but though seedlings were observed on this expedition in several sites they were never seen without the presence of Phoenix caespitosa and therefore we were unable to positively identify these seedlings as belonging to Livistona. The presence of Phoenix caespitosa is typical of the Livistona sites, but in the past the Phoenix leaves have been cut on a regular basis, and the leaves used for weaving and roofing. This practice is less common than in the past, and the sites are generally crowded with Phoenix. However, without knowledge of the ecology of the seedlings, it is not possible to say whether the Phoenix is out-competing the Livistona for resources. The Livistona rosettes are robust and the adults easily overtop the adult Phoenix.


Rosettes:

In Randa, with 41 rosettes, the total population increased by over 80% though the adults decreased by 26%. It will be important to re-visit this site as soon as possible to establish the current status of these rosettes. Elsewhere the picture is variable: the populations at Ribta and Toha and Ditilou have no rosettes, Satabou, Agorogouba and Bankouale have a few, though only in some sub-populations. Wêr and Disay have reasonable rosette numbers.



Juveniles:

Juveniles were not apparent in many sites. In particular, the major sites at Bankouale were without juveniles, At Agorogouba and Disay, however, the population structure appears more normal with a balance of mature adults, juveniles and rosettes.


  1. Conclusions : The Future of the Bankouale Palm




It is clear from the report of Welch and Welch (1998) that the Bankouale palm is in danger of extinction worldwide.


In the Yemen the population is reported to be endangered from felling, though we have no data since 1998. However, the steady decline of the Bankouale palm described by Welch and Welch is confirmed by the current study of the majority of the populations in Djibouti. The populations at Bankouale seem to be in particular danger as there is little regeneration. The two main sub-populations are without rosettes or seedlings and one population of 47 adults is in the middle of the wadi and is therefore in particular danger from flash floods. However, one new sub-population of 6 rosettes does give hope and a possible way forward for saving the palm in Djibouti.



The gardens occupy the most important sites for the regeneration of the palm and have been in existence for some 50 years. The lack of regeneration seems to have started from this time. Though the gardens may be the cause of the recent decline of the Palm, they may also be a possible means of regeneration. Palms grow well in the soil, and the gardens are protected from the worst of the floods. The irrigation is ensured and the gardens could be used as nurseries for the palms and as sites for adults. Compensation for this will have to be provided as the palms will require time and space which would otherwise be devoted to the production of food. It is hoped that we can initiate a rescue plan to ensure the survival of the palm for the future



References


Harper, J.L., 1977, The Population Biology of Plants, Academic Press.


Lebrun, J.-P., Audru, J., and Cesar, J. 1989, Catalogue des plantes vasculaires de la Republique de Djibouti. I.E.M.V.T. no 34

Monod, Th., 1955, Remarques sur un Palier peu connu : Wissmannia carinensis (Chiov. 1929 ) Burret 1943. Bull. Inst. Franc. Afr. Noire, 17a: 338-358.


Welch, H., and Welch, J., 1998. A report on the birds of Djibouti and the Bankouale Palm Livistona carinensis. Ministere de l'environment, du Tourisme et de l'Artisanat, Direction de l'Environment, Biodiversity Report no 4, IUCN Djibouti Biodiversity Project DJI/95/A/1G/99



Acknowledgements:

We would like to acknowledge the help and assistance of Houssein Abdillahi Rayaleh, Ministry of Housing, Urban Affairs, Environment and Land Management in Djibouti, without whose field knowledge and organisational skills the project would not have been a success, and Houmed Ali, Bankouale whose knowledge and abilities in the field crucial to our success. The project was funded in part by a grant from the Game Conservancy Trust, Fordingbridge, Hampshire, SP6 1EF, UK