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The rangeland of north Africa: Typology, yield, productivity and development

H.N. LE HOUEROU (*)

(*) H.N. Le Houérou, Senior Officer in Charge, Grassland and Pasture Group, F.A.O./Rome, Italy.


Introduction
Methodology - Inventoried and mapped areas
Principal types of pasture, their yield and their productivity
Improvement of pasturelands
Conclusions
Bibliography


Summary

This paper gives concise information on surfaces of pastures and rangelands, stocking rates, areas surveyed and mapped, and the methodology which was used (neo-montpellieran).

A bioclimatological classification of North African rangelands is then given, based upon two simple criteria: average rainfall and average minimum daily temperature of January.

The main grazing land types are briefly described, and their surface and productivity assessed from range types mapping and results from grazing experiments and development schemes.

The main conclusions arising from range improvement experiments and range development schemes are given and the achievements so far attained are mentioned for the five countries considered.

In conclusion, the author stresses the fact that after 25 years of research, experiments and extension, we are at the present time on the eve of a breakthrough in range development, which can now be based upon sound technical ground.

However, some problems still persist, especially regarding the training of qualified range ecologists and managers.

Numerous productivity figures are given as an annex, as well as various curves showing average annual productivity as a function of average annual rainfall.

Introduction

The natural pastureland of North Africa covers approximately 60 million hectares from the Red Sea to the Atlantic Ocean.

This figure can be subdivided as follows:

- Semi-arid to humid zone (P > 400 mm): 10 million hectares (woodland, maquis, garrigue, meadow, grassland);

- Arid zone (400 > P > 100 mm): 46 million hectares (steppe, garrigue, fallow land);

- Desert zone (100 > P > 50 mm): 4 million hectares (desert steppe, wadis, maaders, not including Aacheb).

These areas represent two thirds of the non-desert zone (92 million hectares) in Algeria, Egypt, Libya, Morocco and Tunisia.

Together with the 35 million hectares of stubble straw, and cereal fallow, and 1.6 million hectares of fodder crops, these natural pasturelands constitute almost the sole source of sustenance for livestock which, when converted into ovine equivalents, represent an interannual mean of approximately 91 million sheep.

The animal density is thus 1 ovine equivalent per hectare of non-desert land (including 2 million head of Egyptian cattle fed on 1.3 million hectares of bersim).

The overall ratio of livestock to population for the whole zone is:

There is thus approximately one ovine equivalent per person in North Africa. This explains why annual per capita consumption of meat is estimated at approximately 10 kg, as against a desirable level of the order of 40 to 60 kg.

Methodology - Inventoried and mapped areas

The final goal of most phyto-ecological studies has been the integrated development of an area, not only the improvement of pastoral land.

From a strictly pastoral point of view this may be both advantageous and inconvenient.

At all events, the methods of study used here are those of Montpellier. They were elaborated and tested in North Africa during the 1950s by Long, Gounot, Nègre Le Houérou and Ionesco, before being codified and systematised in Montpellier during the 1960s.

Unfortunately, production measurements were too few while the evaluation and mapping work was being carried out.

However, such measures for primary and secondary productivity have been systematically applied for the past 10 years, particularly under the auspices of FAO and, more recently, during the last five years, of CNRS (Centre National des Recherches Scientifiques) and UNESCO.

In 1969, Le Houérou published an interpolatory estimate of the productivity of 500 plant communities occurring over 13 million hectares of Tunisian steppe land.

Similar studies have subsequently been undertaken in Algeria, Morocco and Libya.

The following areas have now been evaluated and mapped on a large and medium scale (1/50,000 to 1/500,000):

- Tunisia (some zones have been mapped several times)

180,000 km²

- Algeria

50,000 km:

- Morocco

50,000 km²

- Libya

25,000 km²

- Egypt

25,000 km²

TOTAL

330,000 km²

The above figures relate only to phyto-ecological maps: maps based on the vegetation physiognomy are not considered here.

Major work is being carried out in the steppes pastures of western Algeria, involving an area of approximately 5 million hectares.

A number of inventories and surveys (many unpublished) that do not include mapping have been carried out, particularly in Libya and Algeria (Le Houérou).

An FAO / UNESCO / CNRS / ORSTOM / INRAT * project, started in 1969, is conducting integrated research towards development in southern Tunisia, as is a United States Desert Biome project.

(*) National Agronomic Research Institute of Tunisia.

Principal types of pasture, their yield and their productivity

It is not my intention to give here a list of the plant communities which occur in the rangelands. Several volumes of my work have, indeed, dealt with this subject. I will limit myself to noting a number of physiognomic types which occur over considerable areas, or which are of economic interest due to their type and quality or to the season in which they produce.

Bioclimates and vegetation

The bioclimates of North Africa are defined here on a basis of two simple and concrete criteria (Le Houérou, 1969 and 1970).

P = average annual precipitation;
m = average of the daily minima in the coldest month (January).

P is inversely correlated with interannual rainfall variability.

It should also be recalled that P is inversely proportional to Potential Evapotranspiration (PET), but has much more local variation than the latter.

P varies from 20 to 2,000 mm according to zone, while PET varies only between 1,300 and 1,600 mm; there is thus no major objection to replacing (which the Emberger index is intended to represent) by P.

This has the advantage of being expressed in the form of concrete data accessible to those with no specialist knowledge of bioclimatology, rather than in somewhat complex indexes which are, after all, only abstractions.

Further, m is correlated with continentality, altitude, the number of days of frost, and the length of rest period in winter.

Thus a two-entry bioclimatic classification is obtained, a simplification of the Emberger method for regional use, that I consider to be a step forward.

We may thus express types of bioclimate and stages of vegetation in terms of P and temperature variants in terms of m.

P > 1,200 mm, Mediterranean bioclimate, very humid (VH).

1,200 > P > 800 mm, Mediterranean bioclimate, humid (H).

800 > P > 600 mm, Mediterranean bioclimate, subhumid (SH).

600 > P > 400 mm, Mediterranean bioclimate, semiarid (SA).

400 > P > 300 mm, Mediterranean bioclimate, arid, upper (AU).

300 > P > 200 mm, Mediterranean bioclimate, arid, middle (AM).

200 > P > 100 mm, Mediterranean bioclimate, arid, lower (AL).

100 > P > 50 mm, Mediterranean bioclimate, Saharan, upper (SU).

50 > P > 20 mm, Mediterranean bioclimate, Saharan, lower (SL).

20 > P mm Eu-Saharan or Saharo Sindian (non Mediterranean) (ES).

In terms of m we have the following temperature variants:

m > 9, very warm winter variants, no ground frost (VW).

9 > m > 7, warm winter variants, no frost under shelter (W).

7 > m > 5, mild winter variants, 1 - 5 days frost under cover (M).

5 > m > 3, temperate winter variants, 5- 10 days frost under cover (T).

3 > m > + 1, cool winter variants, 10 - 30 days frost under cover (C).

+ 1 > m > - 2, cold winter variants, 30 - 60 days frost under cover (Cd).

- 2 > m > - 5, very cold winter variants, 60 120 days frost under cover (VCd).

- 5 > m, high mountain variants, 120 days frost under cover (HM).

In this way we obtain a climate table of 10 × 8 = 80 theoretical combinations, of which about 60 actually exist around the perimeter of the Mediterranean, in particular in North Africa. Certain combinations never occur, for various reasons.

In the diagrammatic form of a climatogramme with P on the y axis, and m on the x axis, the points are grouped according to isoclimatic similarity. Places which are close together on the diagram thus have the same bioclimatic potential; hence the interest of the diagram in interpolating or extrapolating data.

This method may be improved by adding other parameters such as seasonal rainfall, variability of precipitation, summer temperatures and precipitation.

The base values indicated for P and m are the result of study of the distribution of vegetation and the adaptation and production yield of crops - for example the 400 mm isohyet which divides the arid from the semi-arid bioclimates corresponds to the northern limit of the steppes in North Africa. It is also the southern limit of the holly oak and numerous native species, as well as of regular, commercial cereal cultivation by dry-farming.

The 100 mm limit corresponds to the limit of the Saharan vegetation types, to the absolute limit of non-irrigated farming, and to the upper limit of Deglet Nour date trees.

m = 7 corresponds to the lower temperature limit of tropical crops (sugar cane) and certain native species of tropical affinity.

m = 3 is the limit between the high and low steppes.

m = + 1 corresponds to the appearance of cryophytic species (suited to the cold); it is the lower temperature limit of the olive, the carob tree, cactuses, and others.

m = - 2 corresponds to the lower attitudinal limit of the cedar (Cedrus atlantica) and to the appearance of thorny, high-altitude, xerophyte, cushiony species.

m = - 5 corresponds to the upper altitude timber line.

These different bioclimates and their temperature variants correspond to very specific types of vegetation and pastureland.

For the sake of simplicity, we will group together on the one hand the pastureland of the semi-arid to humid zones, and on the other the rangeland of the arid, steppe zones.

Rangelands of the semi-arid to humid bioclimates

This pastureland consists essentially of woodland and deteriorated woodland: maquis and garrigue with a limited amount of meadow, ermes and some 200,000 hectares of natural grassland in humid lowlands with year-round ground water close to the surface.

Forest and woodland

The wooded area covers approximately 9.5 million hectares. Animal production represents 60 to 80 per cent of the economic value of this land *.

(*) See Jansen, 1970; Taton, 1966; Le Houérou, 1971, 1973, 1974.

The following may be distinguished, on the basis of dynamic series and in approximate order of increasing adaptability to dry conditions;

- Zeen oak (Q. faginea) and Afares oak (Q. afares) (deciduous) series;
- Cork oak series (Q. suber);
- Cedar series (Cedrus atlantica);
- Holly oak series (Q. flex);
- Lentiscus olive tree series (Pistacia lentiscus - Olea europaea);
- Aleppo pine to holly oak series (Pinus halepensis);
- Aleppo pine to Phoenicia juniper series (Juniperus phoenicea);
- Barbary thuya series (Tetraclinis articulata);
- Thuriferous juniper series (Juniperus thurifera);
- Phoenicia juniper series;
- Argan tree series (Argania sideroxylon).

The last four series occur in both arid and semiarid bioclimates. Each of these series includes homologous types from full-grown forest to garrigue or maquis wasteland or sword.

The type and quality of production as well as the productive capacity of these wooded pasturelands depend not only on bioclimatic and edaphic factors but also on biological factors.

Certain stages of woodland degradation within a given series are more productive and give a higher quality of forage than others. It can be stated, however, that production is broadly related to the average annual rainfall, when homologous types in each series are compared.

The best grassland of the humid and sub-humid areas may reach a yield of 1,000 - 1,200 kg of dry matter/ha/year, or 400 -500 Scandinavian feed units (FU).

The woodland and maquis yield 500 to 1,500 kg DM/ha/year, or 150 to 500 FU.

These figures were confirmed not only in North Africa, but also under similar conditions to the north of the Mediterranean; however, the garrigues of the semi-arid zone produce only 600 to 800 kg of edible DM per hectare per year (200 to 300 FU): for further details see Long et al., 1967; Liaccos and Mouloupoulos, 1967; Le Houérou, 1964, 1965, 1969, 1971, 1973, 1974; Sarson and Hamrouni, 1974, Maignan, 1974; Van Swinderen, 1973; Le Houérou, Claudin, Haywood, and Donadieu, 1974; Sebillotte, Loiseau et al., 1972.

Potential productivity is often much higher than this. Sound planning and management could produce an increase in production of between 100 and 500 percent (Long et al., 1967).

Grasslands

Marshy soil formation plays a relatively important role in summer forage production. The botanical composition is relatively uniform and consists basically of:

- Festuca elatior subsp. arundinacea;
- Agropyrum elongatum;
- Agropyropsis lolium;
- Phalaris coerulescens;
- Phalaris arundinacea;
- Trifolium fragiferum;
- Lotus corniculatus;
- Tetragonolobus siliquosus;
- Medicago ciliaris;
- Juncus maritimus;
- Juncus acutus, etc.

Unfortunately, these grasslands are permanently over-grazed and their production barely exceeds 1,000 FU/ha/year, although potential productivity is of the order of 3,000 to 5,000 FU (Thiault, 1962; Le Houérou, 1962, 1965, 1969).

Pastureland in arid bioclimates

General

The bioclimates of the arid zone correspond fundamentally to steppe-type vegetation, although there remain 2.4 million hectares of garrigues on the mountains and 600,000 hectares of wooded parkland of argan trees in the south-west of Morocco.

Principal types

The principal types of pastureland and the areas they cover are as follows:


Thousands of sq. km

- Deteriorated woodland and garrigues (Aleppo pine, Phoenicia juniper, Argan tree, Barbary thuya)

30

- Alfa grass vegetation (Stipa tenacissima)

40

- Esparto grass (Lygeum spartum) on more or less gypseous soils

30

- White sage (Artemisia herbs alba) on silty soils, often with calcium carbonate encrustation

105

- Field sage (Artemisia campestris) on sandy soils

45

- Deteriorated steppe vegetation and post grazing ermes (Peganum harmala, Thapsia garganica, Cleome arabica, etc.)

20

- Halphilous thick-leafed vegetation (Atriplex, Salsola, Suaeda, Arthrocnemum, Halocnemum, etc.)

40

- Pseudo-steppe vegetation of Nanophanerophytes on terraces, wadis, and dunes (Ziziphus lotus, Retama raetam, Acacia raddiana, Tamarix sp. pl.), etc.

20

- Cultivated land

55

- Fallow land

105

TOTAL

490

Production and productivity *

(*) Production = actual yields.
Productivity = ability to produce.

The yield of pasture varies a great deal depending on the type of pasture and physical environment, the dynamic stage, and the pressure of animals.

The highest and most regular yield is achieved on sandy soils, and the lowest level on soil with a calcium-carbonate encrusted surface layer and on gypsum.

The average yield of good pastureland with little deterioration over a number of years is of the order of 1 FU or 3 kg of edible DM/ha per millimetre of actual rainfall.

On deteriorated pastureland and on skeletal soils, the production is generally 0.2 to 0.5 FU or 0.6 to 1.5 kg/ha of dry matter per millimetre of rainfall, that is, one half or one fifth of the production of non-degraded pasture on good soil. In cases of extreme deterioration this may fall as low as one tenth.

Certain types of pastureland in topographic depressions which have the benefit of runoff water or underground water courses, for example, that of Cynodon dactylon or of Atriplex, may produce as much as 1,000 to 2,000 FU/ha/year.

Steppe-type pastureland is also characterised by continuous and widespread over-grazing, the average rate of stocking being 1 sheep per 2 hectares, while the animal carrying capacity is not greater than 1 sheep per 4 hectares, on average.

It is also characterised by a removal of firewood from types of pasture vegetation such as white Artemisia or Atriplex halimus.

This removal is on the order of 1 kg of DM per person per day, i.e. for a rural population of 15 million people, an annual removal of 5.5 million metric tons.

Since the average biomass of dry steppe pasture barely exceeds 1,000 kg (including main roots), the area of steppe pasture destroyed each year would in theory be 5.5 million hectares. In fact, this figure is much lower because a certain amount of regeneration occurs during rainy years.

Nevertheless, the using up of woody species for firewood, a considerable increase in clearing for cultivation, and over-grazing cause the desertisation of several tens of thousands of hectares each year between the 50 and 200 mm isohyets.

We are thus witnessing an indisputable, rapid, and often irreversible regression, not only with regard to yield, but, more seriously, with regard to the productivity of steppe-type rangeland.

Proposals for remedying this situation are contained in a number of publications; I will not discuss them here. For further details on the arid pasturelands of North Africa see: Long, 1952, 1954, 1956; Le Houérou,, 1955 to 1975; Le Houérou, and Franclet, 1971; Monjauze and Le Houérou,, 1965; Le Houérou, and Froment, 1966; Froment, 1970; Nègre, 1974; Floret and Pontanier, 1972, 1973, 1974; Floret and Le Floch, 1972; Loiseau and Sebillotte, 1972; Delhaye, Le Houérou, and Sasson, 1974; Le Houérou,, Claudin and Haywood, 1974; Le Houérou, and Ionesco, 1974; Ionesco, 1966; Ionesco, 1972.

Improvement of pasturelands

In the semi-arid areas and above (P > 400) the reseeding of pasture does not pose any special technical problems; thousands of hectares have been established consisting primarily of alfalfa, fescue, rye-grass, burnet, phalaris, sulfa, oryzopsis, sub-clover and annual medics.

Potential yield is of the order of 5 to 10 FU or 10 to 20 DM per millimetre of actual rainfall in good technical conditions and on suitable soil.

The reseeding of grassland in arid zones (P < 400 mm) has generally not been successful, with very few exceptions (for instance, Midelt area in Morocco).

In arid zones, pilot projects for pasture development have been carried out or are in progress on some thousands of hectares (Tadmit in Algeria, Sbeitla in Tunisia, Midelt in Morocco, Garabulli in Libya, Ras el Hikma in Egypt), some over 20 or 30 years.

Moreover, the results obtained by European farmers and stockmen on steppe pastureland between 1900 and 1960 are available. The potential and actual productivity of the pastureland is thus fairly well known.

Development in Tunisia is centered around the planting of forage shrub (Cactus, Atriplex, Acacia), which is encouraged by loans, grants and so on. An FAO/WFP/Government project in Tunisia enabled 50,000 hectares of cactus and several thousand hectares of Atriplex and Acacia to be planted in central Tunisia between 1970 and 1975.

Algeria has just issued a rangeland charter and seems to be progressing towards a solution through the establishment of co-operatives of sedentary breeders over fairly large areas. Forty co-operatives, each 10,000 hectares in size, have been in existence for five years.

In Morocco, an FAO/SIDA project for the improvement of forest rangelands has just been initiated, and range management is being taught at the Forest Engineering College at Sale.

In Libya development units based on the controlled use of pasture, planted forage shrub, and irrigated forage production are in the process of being set up over 250,000 hectares in the Jeffara of Tripolitania.

Conclusions

It appears that after 25 years of research activity, evaluation and mapping, which has resulted in numerous publications and in the diffusion of knowledge and ideas, we are on the threshold of concerted and far-reaching action towards improving the pastureland of North Africa.

Unfortunately, some serious problems persist: the scarcity of qualified technicians, the absence or insufficiency of specialised training and the absence of any competent administrative organisation, structured and represented at the local level, without which there can be no effective large-scale or far-reaching action.

At present the most severe limiting factor is a dramatic shortage of qualified personnel; in the whole of North Africa there are less than five indigenous qualified rangeland experts or ecologists.

Attracting talented young people is, however, an easy problem to solve at the governmental level - all that is necessary is to offer interesting, well-paid careers.

Productivité moyenne estimée des steppes tunisiennes (Le Houérou, 1969)

Table 1 - Data on Biomass Productivity or Yields (after Le Houérou, Claudin and Haywood 1975)

Table 1 - Data on Biomass Productivity or Yields (after Le Houérou, Claudin and Haywood 1975) (Cont.)

Table 2 - Data on Range Value and Yield (Rodin, Vinogradov et al. 1970). Medea, Algeria.


RANGE TYPES

Yield Kg. DM Present

Yield Kg. DM Ha/Yr Potential

FU/Ha/Yr* Range value present

FU/Ha/Yr* Range value potential

Rainfall

1.

Artemisia herba alba and Stipa parviflora on limecrust

350

500

140

200

Upper Arid 400>P>300

2.

Stipa parviflora and Poa bulbosa on limecrust

300

300

120

120


3.

Artemisia herba alba and Lygeum spartum

250

400

100

160


4.

Halophytes

200

250

80

100


5.

Wadi beds with halophytes

220

250

80

100


6.

Alfa, Lyqeum spartum on shallow soils

130

180

50

70

.

7.

Artemisia herba alba with lithophyties and halophytes

200

280

80

100


8.

Artemisia herba alba on limecrust

250

450

100

180

Middle Arid 300>P>200

9.

Noaea mucronata on limecrust

120

200

48

80


10.

Halophytes on limecrust

200

250

80

100


11.

Artemisia herba alba and Lygeum spartum on limecrust

200

300

80

120


12.

Alfa and Artemisia herba alba on lime crust

110

300

45

120


13.

Alfa and Artemisia herba alba on lime crust

220

450

90

180


14.

Alfa grass steppe

20

500

50

200


15.

Artemisia herba alba steppe

200

350

80

140


16.

Steppe of Lygeum spartum

200

300

80

120


17

Alfa and Artemisia herba alba (plains)

220

450

90

180


18.

Alfa and Artemisia herba alba

100

150

40

60


19.

Lygeum spartum and Salsola vermiculata

150

600

60

240


20.

Halophytes in wadi beds

800

1,200

320

480


21.

Dunes with psammophytes

100

150

40

60


22.

Halophytes in saline depressions

70

70

30

30


23.

Alfa and Launea acanthoclada on shallow soils

110

150

45

60


24.

Halophytes and lithophytes

200

300

80

120


25.

Lygeum spartum and Artemisia campestris on flooded plains

270

400

110

160

Middle and Upper Arid 350>P>250

26.

Lygeum spartum and Ziziphus lotus

200

350

80

140


27.

Halophytes and Atriplex glauca

500

500

200

200


28.

Alfa and Launea acanthoclada

120

450

SO

180


29.

Exclosures on stony hills

300

600

120

240


(*) 1 FU = 2.5 Kg DM

Production annuelle consommable des pâturages nord-africains. (Algérie; Le Houérou, Claudin et Haywood, 1974)

GOAT SEMINAR - THE GRASSLANDS OF THE MEDITERRANEAN BASIN AND THEIR IMPROVEMENT BY Dr. LE HOUEROU, FAO EXPERT - SEMINAIRE SUR LES POLITIQUES DE L'ELEVAGE DE LA CHEVRE DANS LES REGIONS MEDITERRANEENNES. LES PATURAGES DU BASSIN MEDITERRANEEN ET LEUR AMELIORATION PAR: Dr. HN LE HOUEROU, EXPERT DE LA FAO.

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