NORWEGIAN UNIVERSITY OF LIFE SCIENCESDEPARTMENT OF INTERNATIONAL ENVIRONMENT AND DEVELOPMENT STUDIESMASTER THESIS 30 CREDITS 2006
RESPONSE OF BIODIVERSITY TO RADIAL DISTANCES FROM TRADITIONAL WELLS IN HAOUSSA, MALI.
SEYDOU FONGORO
RESPONSE OF BIODIVERSITY TO RADIAL DISTANCES FROM TRADITIONAL WELLS IN HAOUSSA, MALI
BY
SEYDOU FONGORO
NORWEGIAN UNIVERTY OF LIFE SCIENCE
NORAGRIC-DEPARTMENT OF INTERNATIONAL ENVIRONMENT AND DEVELOPMENT STUDIES
MAY 2006
Chapter 1
1.0 Introduction
Provision of water for livestock is a necessary requirement for pastoral land use in the dry parts of West Africa. Around the well clusters annual grasses dominate the vegetation, especially during the wet season (James, al. 1999) but remain bare during the dry season. In the piosphere created around individual wells might have contributed to changes in the composition of the herbaceous vegetation (Thrash, 1993). The reasons are because well points promote heavy trampling and grazing (Van Rooyen et al.1990;
Hanan et al .1991; Thomas et al.2000), causing overgrazing (Lange 1969; Jeltsch et al.1997). The effects are profound and important aspect of change in arid and semi-arid rangelands that has been associated with desertification (Hiernaux,1992), The cumulative effects of livestock grazing and trampling are suggested to introduce changes in plant species composition (Thrash, 2000) and to lead in reduction of plant species richness, plant cover and biomass; shifts in palatable plants have clearly been affected and widespread increase in grazing pressure (James et al. 1995a; Landsberg et al. 1996). The use of different wells of different ages might reveal the extent of impact (Fleischhauer;
Bayer & Lossau, 1998). The impacts of wells on the grazing lands could not however be understood without analyzing the traditional systems of water management in the semi- desert region that probably have inbuilt systems that reduce the consequence for the environment.
The livestock grazing intensity gradient associated with artificial watering points has effects on both vegetation and the physical environment. Impacts on the physical environment include changes to soil nutrient levels (Tolsma et al. 1987). The effects on vegetation, increased shrubs mortality and defoliation (Andrew & Lange 1986), changes in herbaceous vegetation (Thrash, 1998) and increase invasive species (Brooks et al.
2006). Perennial plant cover increased rapidly away from watering points (Todd, 2006).
Some studies showed no consistent relationship between herbaceous species diversity and distance from water points (Thrash et al. 1993). In Oshana ecosystem in Namibia, radial distance had significant effects on herbaceous species richness and age of water points
played an influential role (Nangula & Oba, 2004). Other studies showed that grass species richness increased with distance (e.g., Todd, 2006).
In the semi-desert region, bordering the Sahara, pastoral nomads including Arabs and Touareg for several centuries have been able to exploit the harsh environment by sinking deep hand dug wells that provided sources of water and allowed pastoralists expansion further north and east in the Azouad and Adrar regions (Marie, 1977). The region was utilized for wet season grazing using surface rainfall waters in the wadis and pans. However, beginning about the mid-sixteenth century the Arab nomads and the Touaregs of the haoussa region dug deep wells (Deyoko, 2005). The distributions of the wells along the migratory routes opened up areas of grazing that were previously inaccessible. In other areas, grazing and camping by pastoral families were for longer periods and could have set into process vegetation change from the pre-water development periods. However, uptill this day, we lack sufficient scientific information about the impacts of traditional wells on rangeland biodiversity, despite the water points being blamed for initiating processes of desertification, particularly in the region that borders the Sahara desert (Fleischhauer; Bayer & Lossau, 1998).
The traditional wells vary in depth within the radius of 70 to 130 meters. The water is brought to the surface through use of systems of pulleys operated by traction animals creating heavy livestock trampling of the ground 70-200 m from the wells. The traditional spacing of wells appears to be changing. Presently, well densities have increased. Previously, well sites had few well clusters but the clusters are increasing. In our study area, for example, there were more than 35 functional wells within 489-km2. The inter-well distances varied from a minimum of 200 m to several kilometers. The nomadic communities are aware that the spacing and distributions of wells is important for avoiding overuse of the range. Indeed, there is a strong social control over the numbers of wells to be sunk in any area. The local residents who have full control over access to water through delimitations of well ownership establish claims over grazing lands which others wouldn’t be able to use without being granted rights of access.
This study conducted in Novemeber/December 2005 had the following objectives.
(1) To describe wells ownership and management, (2) To assess the effects of the radial distances from traditional wells on plant cover, species richness. (3) To assess effects of
grazing pressure on plant cover and species richness and (4) relate age of wells as predictors of plant cover and species richness.
Chapter 2 2.0. Study area and methods
2.1. Study area
The study was conducted in the commune of Bamba located in the northern part of Mali between 1° 06 and 1° 35 longitude West, 16°59 and 17°51 latitude North (Fig.1).
The region lies at the edge of the Niger River, covers approximately 4776 km2. Rainfall is highly variable between years (Fig.2). Average annual rainfall is rarely more than 150 mm, 95% of the rainfall expected between August and October. The rainy period is from July to October. The year 2005 when the present research was conducted received the heaviest rainfall of 223.2 mm (Meteorological Department, Mali, personal comm.2005).
Generally, the region has minimum temperature of between 15° C and 30° C from December to January and the maximum between 30°C and 45°C from May to June.
Ecologists describe rainfall in northern Mali as extremely variable (de Leeuw, Diarra &
Hiernaux, 1993). Consequently, annual precipitation is a poor indicator of biomass production because of spatial and temporal rainy variability (Bernus, 1974:14-15).
“Useful rainfalls” is a shower of 3 mm or more, followed by a similar shower after an interval of one week (Gallais, 1967:220). The first rain in mid June sufficiently provides moisture to allow grass germination and promote plant growth.
The main landscapes are composed of active and stabilized sand dunes. Sand dunes movements have been used as evidence of desertification in the Bamba commune.
The soil type is sub desert with thin layer. The vegetation is mostly composed of Acacia raddiana, Balanites eagyptiaca and the grass, both perennial, Colocyntthis cittrullus, Cyperus jeminicus, Panicum turgidum; annuals Aristida mutabilis, Boerhavia repens Corchorus tridens, Gisekia pharnacioides, Indigofera aegyptiaca, Indigofera Senegalensis. The ROSELT of Bourem (Observatory Network and Ecological Monitoring in Long Run, 2003) has classified the haoussa in three zones: the south- haoussa zone, north haoussa and the edge of Niger River. The southern zone is located approximately 5 to 30 km to the north of the Niger River. Northern haoussa is located beyond 30 km in the North of the Niger River; the third zone (the edge of the river) is located in less than two km of the Niger River.The three zones vary in their range productivities as illustrated by the productivity measurments taken by Regional Center of
Agronomic Research of Gao in 2002 which for the southern zone varied from 38-947 kg ha-1, for northern zone of 107-788 kg ha-1 and no production at the edge of the river (Regional Center of Agronomic Research, 2002).
Fig1. Location of study area within Mali
mm)all (rain
0 50 100 150 200 250
1971 197
3 1975
1977 197
9 1981
1983 198
5 1990-94
2000 200
5
years
f
Fig2. Rainfall variability in Haoussa region in years
Pastoralism is the main economic activity in the northern Bamba (Haoussa) where mixed herds of sheep, goats, camels, donkey, and cattle are managed. The inhabitants are Touaregs, Arabs, Bellah, Songhay, Fulani, and Bambara. The traditional systems of land use by the nomads in the Houssa region for several centuries has been an established practice of transhumance between the wet season grazing areas that took them across international borders or deeper into the Sahara Desert borders, as rainfall shifts northwards and southwards. The Gourma on right bank of the Niger River and the Haoussa on left bank are important transhumance routes for the migratory herds. During the wet season which lasts three to four months the nomads exploit pasture growth and surface water. As the surface water dries up, the nomads move back to their dry season well where they remain until the next rainy season. The southbound migration during the dry season, take individual herding families to their traditional wells.
From the well site camps on daily basis pastoral families travel between water points to where fodder is available. As strategy of pasture exploitation, camps have to be moved several times. As Fig.3 shows, between mid June and November few animals are dependent on the wells but greater numbers are watered between March and May suggesting that the wells are used throughout the year. There is no regulation on how closer to the well a camp is permitted. For the safety of women and children a family may
prefer to camp a bit far from well, others may camp far to allow the younger animals who need to graze at night in the vicinity of the camp. Still others may camp closer to wells for access to water and travel to pasture area in the remaining time of the day; while other herders may camp far from traditional wells for access to pasture then prefer traveling long distances to the wells. Small livestock have very limited ability to travel long distances with maximum 13 km a day from wells on average. As dry season progresses, distance between water-sources and pasture increases. This might force most nomads to move for the next water points. The communities camp around the traditional wells to exploit pastures. They move their camps depending on pasture availability.
Fig3. Livestock movement around Traditional well in time. The concentrated dots indicate periods of greater dependence on the wells
Fig4. Traditional wells distribution in the Haoussa region.
Table1. Description of Traditional Wells
Wells Location Description
Inamankor 17˚10’34’’ North 01˚25’17’’ West. Watering system is by animal tractions, 45 years old, circumference about 3.45m,
used throughout the year
Clanssar 17˚19’56’’ North 01˚30’46’’ West Watering system is by animal tractions, 80 years old, circumference about 5.62m,
used throughout the year
Tabahockomat 17˚03’34’’ North 01˚22’93’’ West Watering system is by animal tractions, 3 years
old, circumference about 6.28m, used throughout the year
Tamayort 17˚11’37’’North 01˚20’82’’ West Watering system is by animal tractions, 150years
old, circumference about 6.28m, used throughout the year
Tintates 17˚16’81’’North 01˚19’74’’ West Watering system is by animal tractions, 350 years old, circumference about 9.42m,
used throughout the year
Sidi mousse 17˚10’96’’North 01˚15’05’’West Watering system is by animal tractions, 60 years old, circumference about 6.28m,
used throughout the year
2.2. Field methods
Based on the distance of 35 km in the north from the Niger River, all wells currently utilized for the study are listed. The selected wells were all located in the north, on the left bank of the Niger River; covering 489 km2 of the southern zone of Haoussa, the distributions of the wells are shown in Figure 4. The ages of the wells varied from 3 years to 350 years (Table 1). The minimum distance between wells was 5 km. Key informants from each fraction (six fractions) were used. I worked with a man who spoke Arabic, Tamashek and French. A total of six key persons were interviewed to understand:
(i) well ownership systems, (ii) rules used for the use of water of wells and (iii) how the water was lifted from wells (iv) as well as understanding the age of wells.
Between November and December 2005, for the selected wells, the field team located two 1.4 km transects radiating from each well in opposite compass directions (Fig5). Because of the heavy trampling around the wells and the piosphere created, all transects were set at 200 m from the wells. Transects were marked using the GPS (Global Positioning System) to fix the direction. We then used systematic random sampling methods to collect the vegetation data (grasses and trees). For grasses (perennial, annual), we used 1x1 m plots. In each plot ( n = 24 plots) we recorded grazing pressure, herbaceous cover was estimated, abundance were recorded at 50 m interval between plots. For shrubs we used 2 x 2 m plots to record the cover, abundance at 100 m of intervals. We then used 20 x 20 m plots to tree species and cover. In total 12 plots for trees and shrubs.
West
Est.
Fig5. Two 1.4km transects around well
Well
2.3. Data analysis
Herder narrative described wells ownership and management. The effects of radial distances from wells on plant cover, species richness were analyzed using linear regression and logistic curves fitted. Variations of perennial and annual covers with different wells were tested using ANOVA. To assess the effects of grazing pressure on plant cover and species richness, we used linear regression and logistic curve was fitted.
A non-linear regression model was considered to be the best-fit model only when it explained significantly more of the variation than the linear model. To relate age of wells as predictors of species richness and plant cover, one-way ANOVA was used.
Statistical analysis were performed on all dependent variables using Minitab software (2004) version 14.12.0 with significance level fixed at p<0.05.
Chapter 3 3. Results
3.1. Wells ownership and management
In northern Mali (Haoussa region), wells provide freshwater both for animal and human consumptions. The wells varied in depth within the radius of 70 to 130 m and circumference of 3.45 to 9.42 meters. Goat and sheep were watered at the wells daily, while the watering interval for the camel was three to seven days. Cattle were watered two to three days intervals. During periods of severe droughts the intervals of watering were decreased. Traditional wells in Haoussa region were the property of the fractions. A fraction referred to a territory with spatial delimitation. Wells belonged to individual families but they were constructed with the resources of the fraction, thereby the ownership was maintained by individual fractions. The fraction is responsible for wells management and controlled access to the wells by people from outside the fractions.
Pastoralists residing in a fraction where the wells are located had priority of access, while non-resident pastoralists needed prior arrangements from the fraction chief and by the owner of the fork for working the pulleys for lifting water. If the water of the well is limited, the non residents are asked to move to other wells. Usually, the well users were not required to pay taxes with the exception of the Tabahockomat well (Table 1) where a pastoral committee taxes the users at 10 F cfa ($0.01) for 20 liters of water.
The residents of the fraction and non-residents contributed to the digging of new wells and maintenance of existing wells. The contribution could be in terms of money or labour. According to my informants, there were strict regulations as to who may dig wells in the territory of each fraction. The decision comes from the chief of that fraction. He too may not have authority for the development of wells until the fractions traditional superior grants such permission. This was the case of El Sidi Cedeq and Ahel Lawal fractions where the last decision comes from Ahel Lawal’chief (Table1).
Drawing of water from the deep wells involved animal tractions using systems of fork, pulleys and ropes tied to animals (Fig7). A fork was made from tree trunks. Holes through which pulleys rotated were made through the tree trunks, the pulleys made from Balannites aegyptiaca or Acacia raddiana. The pulleys were made by craftmen and highly priced. A pulley on average cost 3000 to 4000F (CFA) an equivalent of $5.45 to
$7.27. The pulley, ropes and bucket for drawing water were private and were not left at the wells but transported to the camps (tents) after watering. The watering is by skin buckets of about 15 liters tied to a rope which was passed over the pulley and the other end tied to traction animals. Usually, pairs of donkeys (Fig7) or camel were used. The animals are driven for a distance of up to 80-150 m to lift the water container from the well. After water was of pulled and poured into a trough the traction animals were driven closer to the well, the process which allowed the lowering of the rope into the well and the process of pulleys, the water container were repeated again. Individual wells may be operated by multiple pulley systems, which varied from well to well, related to the depth and amount of water.
Individual families using the wells may have their own fork. For the wells included in the current study, the numbers of forks varied from 2 to 9 (Fig6). A fork was owned by a person or a tent but a large group of people used someone’s fork when the owner was absent but after gaining permission. If the animals of the owner of the fork returned, he would usually take over the use of the fork and the pulleys although the outsiders might not have finished watering their animals. The implications being that the rights to the use of the wells were different between the members of fraction and the outsiders. I was told that most conflicts arose when the outsiders refused to give up using the fork. One such case occurred in 1996 when there was misunderstanding among the users over the Inamankor well (Table 1). The conflict was settled by the community at the water points and any outstanding issues settled at the pastoral tents. If not settled such conflicts sometimes resulted in fatalities, particularly during years of water and pasture shortages.
However, such conflicts were rarely reported to the government authorities. When I asked why every body in the fraction did not make their own fork in order to avoid conflict, I was told, in the case of Inamankor well, the patriachal parent was the first to come in the area and established ownership over the well that has been dug by others between 1913-1914. The patriarchal head was responsible for removing the sand, repairing the well and thereafter his family took responsibility for managing the well.
Similarly, an elder claimed that the Tintates well (Table 1) was dug by his ancestors.
Thus, according to the local custom of the Arabs and the Touareg nomads of Azaoud, the wells belonged to the family whose ancestor first initiated the digging.
Fig6. Traditional well with four forks
Fig7. Pairs of donkeys watering at Traditional well
3.2. Effects of radial distances on plant cover, species richness
Radial distances had significant effects on plant cover, species richness (all p<
0.001). Annual and perennial covers increased away from the wells and were unchanged between 200-800 m (p < 0.001, Fig8b, Fig8d). Grass cover, when the data of perennial and annual covers were combined occurred also unchanged between 200-800 m. This indicated that a large amount change in plant cover occurred within 800 m of the wells (p<0.001, Fig8a). Even in transects most distant from wells, grass cover did not exceed 5%. We found significant difference between annual and perennial mean cover (p
<0.001). Perennial mean covers differed significantly for all the wells (p = 0.8, Fig11b).
Moreover, annual mean cover also differed significantly for all Traditional wells (p
<0.001, Fig11a). At species level, over fifteen annual species, six perennial species and six tree species were recorded. Cover and frequency of Boerhavia repens (p<0.0001, Fig9b, Fig10b), Gisekia pharnacioides (p<0.0001, Fig9c, Fig10a) and
Trianthema pentandra (p<0.0001, Fig9a) increased away from the wells. The remaining species (all p>0.05, Table2) and woody cover (p = 0.52, r2 = 0.11, Fig8c) did not appear to vary with distances from wells. Grass species richness (p<0.0001, r2 = 0.94, Fig12a) also increased with distances and the fit of the regression was good. However tree species richness did not appear to respond (p = 0.70, r2 = 0.01, Fig12b).
Table2. Grasses species cover along radial distance from Traditional wells in the haoussa region.
Species Autors Distance (m) . 400 600 800 1000 1200 1400
Aristida mutabilis (Trinius, Carl Bernhard von) + + + Boerhavia repens (Linnaeus, Carl) + + + + + +
Cenchrus biflorus (Roxburgh, William) + + + Cenchrus prieuri (Kunth, Karl Sigismund) +
Corchorus tridens (Linnaeus, Carl) + + + +
Dactyloctenium aegyptiacum (Willd, H.B) + + Eragrostis tremula (Lamarck, Jean Baptiste) + Fagonia cretica (Linnaeus, Carl) + +
Gisekia pharnacioides (Linnaeus, Carl) + + + + + + Indigofera Senegalensis (Lamarck, J. B.A.P.M) + + + + + + Indigofera astragalina (Candolle, Augustin .P) +
Indigofera strobilifera (Hochst) + + + +
Mollugo nudicaulis (Lamarck, J.B.A.P.M) + Trianthema pentandra (Linnaeus, Carl) + + + + + + Tephrosia bracteolata (Guillemin, J.B.A) +
Acacia sieberiana (Candolle, Augustin .P) + + +
Aerva javanica (Juss) + + + + Colocynthis citrullus (Kuntze, Carl Ernst Otto) +
Cyperus jeminicus (Rottbøll, Christen Friis) + + + + Cyperus conglomeratus (Thwaites, G.H.K) + + + Panicum turgidum (Forsskål, Pehr) + + + + +
(a) (b)
(c) (d)
ccC
distance (m)
grass cover (%)
1400 1200
1000 800
600 400
200 6
5
4
3
2 SR-Sq 0.55128970.3%
R-Sq(adj) 65.9%
annual cover (%)
200 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5
distance (m)
1400 1200 1000 800 600 400
S 0.383295
R-Sq 80.1%
R-Sq(adj) 77.2%
distance (m)
woody cover (%)
1400 1200 1000 800 600 400 200 20
15
10
5
0
S 5.28006
R-Sq 11.3%
R-Sq(adj) 2.4%
distance (m)
perennial cover (%)
1400 1200 1000 800 600 400 200 2.00 1.75 1.50 1.25 1.00 0.75 0.50
S 0.183808
R-Sq 68.9%
R-Sq(adj) 64.3%
Fig8. Relationship between plant cover and radial distances from Traditional wells in Haoussa region, for (a) grass, (b) annual grass, (c) woody, (d) perennial grass.
(a)
Distance (m)
T.pentandra cover (%)
1400 1200
1000 800
600 400
200 0.35 0.30 0.25 0.20 0.15
0.10 SR-Sq 0.028625588.2%
R-Sq(adj) 86.4%
(b) (c)
Distance (m)
B.repens cover (%)
1400 1200
1000 800
600 400
200 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1
S 0.0666770
R-Sq 84.7%
R-Sq(adj) 82.5%
Distance (m)
G.pharnacioides cover (%)
1400 1200
1000 800
600 400
200 0.5
0.4
0.3
0.2
0.1
S 0.0273882
R-Sq 94.2%
R-Sq(adj) 93.4%
Fig9. Relationship between plant cover and radial distances from Traditional wells in Haoussa region, for (a) T. pentandra, (b) B. repens, (c) G. pharnacioides.
(a) (b)
400
Distance (m)
G. pharnacioides frequency (%)
1400 1200 1000 800
600 200
3.5 3.0 2.5 2.0 1.5 1.0
S 0.180728
R-Sq 91.9%
R-Sq(adj) 90.7%
Distance (m)
B. repens frequency (%)
1400 1200
1000 800
600 400
200 15.0 12.5 10.0 7.5 5.0
S 1.22217
R-Sq 88.7%
R-Sq(adj) 87.0%
Fig10. Relationship between grass species frequency and radial distances from Traditional wells in Haoussa region, for (a) G. pharnacioides, (b) B. repens
(a) (b)
Fig11. Mean (±SE) for Annual grass cover (a) and Perennial cover (b) showing response with wells
Wells
Perennial grass cover (%)
Tintates Tamayort
Tabahockomat Sidi Mousse
Inamankor Clanssare
3.5 3.0 2.5 2.0 1.5 1.0 0.5 Wells 0.0
Annual grass cover (%)
Tintates Tamayort
Tabahockomat Sidi Mousse
Inamankor Clanssare
8 7 6 5 4 3 2 1 0
(a) (b)
distance (m)
grass species richness
1400 1200
1000 800
600 400
200 1.50
1.25
1.00
0.75
0.50 SR-Sq 0.070613194.7%
R-Sq(adj) 93.9%
distance (m)
Tree species richness
1400 1200
1000 800
600 400
200 0.06 0.05 0.04 0.03 0.02 0.01 0.00
S 0.0205641
R-Sq 1.5%
R-Sq(adj) 0.0%
Fig12. Relationship between plant species richness and radial distances from Traditional wells in Haoussa region, for (a) grass, (b) Tree.
3.3. Effects of grazing pressure on plant cover and species richness
Grass cover (p<0.001, r2 = 0.41, Fig14a) and grass species richness (p<0.001, r2 = 0.68, Fig13) decreased linearly in relation to grazing pressure. Only, covers of B. repens (p<0.0001, r2 = 0.68, Fig14d), G. pharnacioides (p <0.0001, r2 = 0.63, Fig14c) and T. pentandra (p<0.0001, r2 = 0.58, Fig14b) showed negative correlation to grazing pressure.
66.7%
R-Sq(adj) 68.1%
R-Sq
0.165488 S
0.50 0.75 1.00 1.25 1.50
Light Moderate Heavy
Grazing pressure
Grass species richness
Fig13. Relationship between grass species richness and grazing pressure
(a) (b)
T. pentandracover (%)
56.3%
58.2%
0.0513330 S
R-Sq R-Sq(adj)
0.05 0.10 0.15 0.20 0.25 0.30 0.35
Light Heavy
Grazing pressure Moderate
38.6%
R-Sq(adj) 41.3%
R-Sq 0.739512 S
2 3 4 5 6
Light Heavy
Grass cover (%)
Grazing pressure Moderate
(c) (d)
67.4%
R-Sq(adj) 68.8%
R-Sq
0.0909408 S
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
Grazing pressure Moderate
62.0%
R-Sq(adj)
63.7%
R-Sq
0.0654519 S
0.1 0.2 0.3 0.4 0.5
Light Heavy
Grazing pressure Moderate
G. pharnacioides cover (%)
B. repens cover (%)
Light Heavy
Fig14. Relationship between plant cover and grazing pressure, for (a) grass, (b) T. pentandra, (c) G. pharnacioides and (d) B. repens
3.4. Age of wells as predictors of plant cover and species richness
When we combined grass species richness data for Tintates and Tamayort in age category 3-45 (youngest), for Inamankor and Tabahakamat in age category 150-350 (oldest), for Clanssar and Sidi Mousse in age category 60-80 years, the analysis showed grass mean species richness to differ for age categories 150-350 to age category 3-45 years and 60-80 years (p<0.0001, Fig15a), but did not for age category 60-80 and 3-45 years. The higher grass mean species richness was found for the oldest category of 150- 350 years. Grass mean cover differed significantly for all age categories (p<0.002, Fig15b). Higher grass mean cover was in youngest category 3-45 years (6.1%).
(a) (b)
0 1 2 3 4 5 6 7 8 9
3-45 150-350
Age category (years)60-80 0.0
0.2 0.4 0.6 0.8 1.0 1.2
3-45
Age category (years)60-80 150-350
Grass mean cover (%)
Grass species richness
Fig15. Mean (±SE) for grass species richness (a) and grass cover (b) showing response to Age category of wells.
Chapter 4 4. Discussion
4.1. Wells ownership and management
We found, the traditional wells in haoussa region to be the property of the fraction.
The wells users were not required to pay taxes for access to water but could contribute labour for the maintainance of the well. In this regard excludability over water points poses problems when decentralisation in mali encourages control over local resources.
The only exception for the Tabahockomat well where a pastoral committee taxes 10 F cfa ($0.01) for 20 liters of water for which the initiative was purely external encouraged by NGOs. The community at large considers this as interferance of the traditional system of water management.
Under the traditional system, the ownership strengths the social relation in the fraction and the wells are constructed with the resources of the fraction thereby the fractions are committed for their maintenance in contrast. The wells created under donor funded programs, very often experienced conflict because they lacked clearly laid down procedures for priority over use of the wells (de Boer, 2000). We found powerful traditional institutions could contribute to rangeland biodiversity conservation through strict restriction of access and control on animal numbers watered at each well.
The decision to do so is a long and complex process. The reason for restricting the rights to dig new wells is linked to pasture management. For individual fractions, herders are concerned that development of more wells will have pulling effects of other pastoralists into their territories that would result in overexploitations of the pastures.
Wells in Haoussa region are operated by animal tractions. For wells deeper than 40 m that use camel traction amount of water extracted is up to 500 liters per hour (de Boer, 2000). This limited yield of water may be environmental friendly. Another study comes to confirm that management type of water plays important role. Privately managed boreholes have few livestock numbers than do group and government managed boreholes (Roe and Fortman. 1981). In Northern Senegal, routes leading to the wells are closed after a period of five years to allow vegetation to generate while others that have been left as fallow are used (Toure, 1988).
4.2. Effects of radial distances on plant cover, species richness
Our finding showed that radial distances have significant effects on plant cover, species richness. Grass cover and grass species richness were after 800 m from the wells, while in the piosphere zone the vegetation indicators were highly impacted. One reason why the 800 m zone had greater cover and species richness was probably being a transitional zone, animals walking to water spent less time in the area. The area also takes the benefits of rest during the wet season when the herds are moved from the wells.
However, around the wells, the impacts on vegetation indicators were greater because of greater concentrations and trampling. As in other studies conducted in Namibia, the grass cover increased with increasing distances from water points (Nangula & Oba.
2004). We found significant difference between annual and perennial mean cover which could be attributed to time and useful rain. In 2005, when the present research was conducted the area received the heaviest rainfall of 223.2 mm and at the time of collecting the data the livestock was mostly far from wells relying on surface water. The lower stocking density (estimated at 0-16 Goats/km2) allowed annual grasses to germinate, confirming what others have reported that closer to water points annual grasses is more abundant during the wet season (James, al. 1999). In the areas immediately close to the wells i.e. 100-200 m continuous trampling (Lange,1969) and heavy grazing might change grass species composition (Larsson, 2003) ). In other studies it has been shown that perennial plant cover increased rapidly away from watering points (Todd, 2006). In our study, Boerhavia repens, Gisekia pharnacioides and Trianthema pentandra covers increased away from the wells implying that the species were sensitive to livestock grazing and heavy tramping. The remaining species and woody covers did not appear to vary with distances from wells. Furthermore, radial distances from water points had significant effects on herbaceous species richness (Nangula & Oba. 2004;
Todd, 2006). Overall, increased plant cover and species richness away from the wells could be largely attributed to reduced tramping and grazing pressure. A previous study conducted by Deyoko (2005) discounted the effects as a reponse of soil texture. In the study area the sub desert soil appeared to have had little influence on the variations of plant cover and plant species richness. The crucial factor was rainfall and soil moisture (de Leeuw, Diarra & Hiernaux, 1993)
4.3. Effects of grazing pressure on plant cover and species richness
Plant cover and grass species richness decreased linearly in relation to grazing pressure gradients. Only, the cover of B. repens, G. pharnacioides and T. pentandra showed negative correlations with grazing pressure. The finding supported the evidence that provision of water points rises grazing intensity (Van Rooyen al. 1994). In other regions such as the semi and humid areas of southern Africa heavy use around water points resulted in bush encroachment (Martens. 1971; Wergen. 1977; Tolsma, al. 1987;
Skarpe, 2000) which was not evident in Northern Mali. The impact of grazing pressure around water points showed a general trend as reported for southern Africa and south- western and North-America (Jeltsch, al. 1997). Since livestock are more likely to walk closer to get watered plant cover and species richness are likely to be impacted by livestock grazing; Boerhavia repens, Gisekia pharnacioides, Trianthema pentandra are palatable to livestock and might constitute important component of forage.
4.4. Age of wells as predictors of plant cover and species richness
Grass mean species richness differed for age categories 150-350 to 3-45 years and category 60-80 years, but did not for 60-80 and 3-45 years. Higher grass mean species richness was found for the oldest category 150-350. Grass mean cover differed significantly for all age categories. Higher grass mean cover was in younger category of 3-45 years. Increase in age of wells might increase species richness but progressive loss of plant cover. This is in contrast to the studies conducted in Namibia where herbaceous species richness declined in response to water point age (Nangula & Oba. 2004). In response to the age of water sources, gradual negative changes in desirable species composition and vegetation cover, has been reported by others (Larsson, 2003).
Chapter 5 5. Summary
In Haoussa (northern Mali), the traditional wells ownership was maintained by individual fractions. A fraction refers to a territory with spatial delimitation. The fractions were responsible for wells management and control access to the wells by people from outside the fractions. The wells users were not required to pay taxes whether residents or non-residents. Radial distances from wells had negative effects on plant cover and species richness. Annual and perennial cover increased away from wells and unchanged from 800m but annual grass was dominant. However, woody cover and tree species richness did not appear to vary with distances from wells. At species level, only cover and frequency of Boerhavia repens, Gisekia pharnacioides and Trianthema pentandra increased away from Traditional wells, suggesting that B. repens, G. pharnacioides and T. pentandra were in majority and fairly distributed across radial distances from wells.
Grass species richness also increased with distances. Plant cover and grass species richness decreased linearly in relation to grazing pressure. Only, cover of Boerhavia repens, Gisekia pharnacioides and Trianthema pentandra showed negative correlation to grazing pressure, suggesting B. repens, G. pharnacioides and T. pentandra are palatable to livestock and constitute important component of forage. The highest grass mean cover was found in younger category 3-45 years while the oldest category 150-350 years showed the highest grass mean species richness; suggest age of wells played an influential role. Increase in age of wells might increase species richness in contrast to grazing pressure but progressive loss of plant cover. Over all, increased in plant cover and species richness away from wells were largely attributed to reduced tramping and grazing pressure.
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Appendix Questionnaires
Village:
Date:
Respondent name: interviewer name:
1-what do you do as main activities in rainy season?
………
………..
2-What do you do as main activities in dry season?
………
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3-do you have:
Sheep Yes No Cattle Yes No Camels Yes No Donkeys Yes No 4-how many well do you have around?
……….
………
……….
5-To whom do well do belong?
………..
……….
………
……….
6-Do you have rules of using the wells
Yes No
7-How do the rules function?
………
………
8-Do the rules in respect by the users?
………
………..
……….
9-what explain the no respect of rules by the users?
………
………
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10-Do you have any conflict around the wells?
Yes no 11-Tell me about different conflict happed and the year
………..
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12-what could be the cause of conflict?
………..
……….
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13-How the conflict is resolved?
……….
………
14- Are the conflict resolution strategies effective ?
……….
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15-Do animals graze around the well in rainy season?
Yes no
Why………..
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16-How do you take out water from well?
……….
……….
17-do you know the age of this well
………..
………
……….
And its size?
………
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18-Do you use well in:
full year:
dry season:
rainy season:
why
………
……….
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19-Do this well a permanent source of water in use?
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20-Do both animals and human use the same well for drink?
………
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21-do you know any disappeared tree around the well?
………
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22-do you know any unfunctional well?
………
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23-What are the most used wells?
………
………
24-How many livestock/persons are supplied in water by this well?
………
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25-Do you wish many wells?
………
……….
And why
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