Assessment of the effects of changing land use from pastoralism to crop farming on Lake Nakivale wetland system in Isingiro District , Uganda

The paper assessed the effects of changing the land use from transhumant pastoralism to crop farming on Lake Nakivale Wetland system. Semi-structured questionnaire was administered directly to 315 respondents from randomly selected households in three parishes bordering Lake Nakivale Wetland. In order to trace trends in land use practices overtime and understand the associated environmental problems, analysis of satellite images was carried out, structured interviews and focussed group discussions held. Five transect walks of 6 km perpendicular to the wetland were carried out to confirm information generated from the analysis of satellite images and discussions. The results indicate that over the last two decades, land use practices around Lake Nakivale Wetland have changed at an alarming rate from semi-nomadic and transhumant pastoralists’ way of rearing cattle to sedentary subsistence crop farming, leading to unprecedented human induced environmental problems such as land degradation, loss of wildlife habitat, wetland encroachment, destruction of important historical and cultural sites as well as siltation of Lake Nakivale. Integrated land use planning and management should guide the restoration program, if the wetland and the surrounding landscape are to regain their integrity.


INTRODUCTION
In recent years, there has been much concern on the increased destruction and conversion of Uganda's wetlands to other forms of land use like human settlement and agriculture (Stuip et al., 2002;IUCN, 2003;Kyambadde, 2005;Kaggwa et al., 2009;Mugisha, 2011).Lake Nakivale Wetland is one of the vital ecosystems of international importance (Ramsar Site) in the country that were experiencing human Nakivale Wetland has over the last two decades changed from semi-nomadic and transhumant pastoralism to subsistence crop farming at unprecedented rate, with far reaching negative effects on the conservation of the wetland and wildlife therein.
Lake Mburo -Lake Nakivale Wetland system supports globally threatened species of birds such as Papyrus yellow Warbler (Chloropeta gracilirostris), red faced barbet (Lybius rubrifacecies), Papyrus Gonolek (Laniarius mufumbiri) and shoebill (Balaeniceps rex).It also hosts two of the endangered cichlid fish species Astatoreochromis sps and Astatotilapia sps.In addition, it is the only area in Uganda in which the Impala (Aepyceros melampus) is found (WMD and NU, 2008).Other animal species such as hippopotamus (Hippopotamus amphibius), sitatunga (Tragelaphus spekii) and Nile crocodile (Crocodylus niletic reside in the wetland.A recent survey indicates that wetland system has a total of 123 plant species.Of all of these, 16 are trees, 21 shrubs and 86 herbaceous (Nature Uganda 2009 a).
The wetland is located in Isingiro District and falls within geographic coordinates of 30°49´ -31°04´ East and 00°33´ -00°47´South.In the middle of the wetland is Lake Nakivale which is 14km long, 6km wide and has a maximum depth of 3.5 metres at high water level (NAFIRRI, 2010).The Wetland system intertwines with Lake Kachera and Lake Kijjanibarola Wetlands through River Rwizi Wetland, which is the major inflow as well as outflow that feeds into Lake Victoria.The local people living adjacent to the wetland regardless of their sex, ethnicity, nationality and socio-economic status utilise the wetland resources such as fish, medicinal herbs, handcraft and building materials to improve their livelihoods.However, of great concern are the poor farming practices which have triggered environmental problems that are threatening the conservation of the wetland.
The increased human settlement and simultaneous shift in land use practices around Lake Nakivale Wetland system can be traced as far back as late 1950s when Rwanda experienced tribal and ethnic conflicts that forced Tutsi who were pastoralists and rulers to flee with their herds of livestock into exile in Uganda (Bagenda et al., 2003;Bitware, 2012).They settled around Lake Nakivale Wetland.In 1960, the land estimated to be about 138.5 km 2 was designated as a refugee resettlement area.In 1990 the Tutsi waged a war against the Hutu government in Rwanda and finally toppled it in 1994.Most of the Tutsi pastoralists returned to their motherland, but were replaced by the crop growing Hutus and other different groups of refugees from different countries.Unlike the pastoralists whose traditional livestock rearing practices were able to maintain stable ecological balance through mobility without causing great pressure on the ecosystem (De Carvalho, 1974;Simpkin, 2005;PFE et al., 2010;Secretariat of the convention on Biodiversity, 2010;Bhasin, 2011), the activities of the new crop growing refugees degraded the wetland and adjacent landscape.They cleared natural vegetation and opened land for food production which exposed soils to erosion leading to land degradation and siltation of Lake Nakivale.The land use rapidly changed from seminomadic and transhumant pastoralism to sedentary subsistence crop cultivation with a myriad of environmental challenges.The conversion of land cover and the wetland increased in size and intensity at a high rate.The situation was also compounded by the influx of over 10,000 nationals into the refugee resettlement area in search of land for food production.Many of them settled on the fringes of Lake Nakivale Wetland, exerting more pressure on the wetland resources.The problem was also exacerbated by the government policy that supported refugees to participate in food production activities as a means of reducing reliance on relief food items and promoting self reliance amongst refugee community (Bagenda et al., 2003;Hunter, 2009).
Although the intention of promoting self reliance within refugee community was good, agricultural expansion became a key driving force of land cover changes and wildlife decline (Mundia and Murayama, 2009).Indeed, the use of land adjacent Lake Nakivale Wetland for crop production and human settlement unlike pastoralism culminated into interlinked, and interdependent environmental problems such as encroachment of wetland, loss of natural vegetation cover and wildlife species as well as soil erosion, leading to the siltation of water bodies to mention a few.This adversely compromised the wetland's capacity to perform natural functions (Nature Uganda, 2009 a).The replacement of pastoralists with crop farming community promoted poor land use practices like clearing of forests and bush land to open up land for crop farming, concentrating grazing of the remaining livestock in flood plains, wetlands and surrounding steep hills, setting up human settlements on the fringes of Lake Nakivale Wetland, using of fire to burn natural vegetation and crop residues as well as extending the crop farming into the wetland.The traditional practice of clearing bush land as a means of opening land for crop production exposed the bare land to soil erosion and other forms of degradation (Sharma et al., 2007).
The earlier research on wetlands in Uganda focused on ecological, socio-economic and community attitude assessment (Bagenda et al., 2003;Nature Uganda, 2009 a and b), sustainable utilization of wetland resources and services (Kyambadde, 2005;Nyakana, 2008;NAFFIRI, 2010) and a few studies which have tried to look at the effects of land use put much emphasis on people's livelihoods and farming practices (Mirongo, 2005;Makalle et al., 2008).Therefore, it is against the foregoing that this study was carried out to assess the effect of rapid shift from the traditional transhumant pastoralists' life style and land use practices to sedentary subsistence crop farming, on the wetland system.More specifically, the study points out the key threats to the conservation of Lake Nakivale wetland which cropped up as a result of this change.These are: degradation of wetlands, loss of vital wildlife habitats and important cultural and historical wetland forests, siltation of Lake Nakivale as well as increased human pressure on wetland resources.The findings show that introduction of crop farming on Nakivale refugee settlement area and the landscape adjacent Lake Nakivale Wetland has had far reaching negative impacts on the conservation of the wetland system.It is crucial for the policy makers and wetland managers to implement appropriate interventions to restore the integrity of the wetland through integration of land use practices into the planning and management of wetlands.

MATERIALS AND METHODS
The study area encompasses the wetland system around Lake Nakivale and Landscape within a radius of 6 km from the edge of the wetland.Triangulation approach that applies multiple methods, (qualitative and quantitative) to capture data which was used.The study primarily utilised between-method triangulation and to some extent data triangulation by designing household survey tool, the questionnaire, in a manner that targeted both the household heads and other members of a family.The use of triangulation technique was the best suited for this study because it created a deep understanding of pastoralists' and crop farming communities' land use practices on one hand and wetland management issues on the other.At the same time, it enhanced the accuracy and validity of data.Participatory Rural Appraisal (PRA) techniques such as, focused group discussions and structured interviews were used to generate a deeper understanding of environmental and socioeconomic problems emanating from changes in land practices as a result of crop farming community replacing pastoralists.
A total of 315 households were randomly selected and either the household head or another family member was administered with a semi-structured a questionnaire.In total 153 of respondents (48.6%) were male and 162 (51.4%) were females.Most of respondents involved in the survey had lived in the study area for more than 10 years.One hundred and sixty nine respondents (53.7%) had lived in the study area for more than 10 years, 64 (20.3%) had lived in the area for a period of 2 to 5years, 62 (19.7%) for 6 to 10years and only 20 (6.3%) respondents for a period less than one year.
The group discussions were kept focused by the use of a semistructured group discussion guide.The guide was first pretested using six members of Rukinga fishing village beach management committee to assess its effectiveness in generating desired information and also determine the length of time required to obtain adequate and meaningful data.After the pre-test, a few alterations were made to fine tune the guide in order to make the questions clearer and well understood by the group.In total, four group discussions were held as follows: Rukinga Village (n=10), Kikutsi Village (n=6), Rubondo Village (n=8) and Kabazana Village (n=10).Assessment of satellite images that were taken in July 1984, July 1999 and August 2010 complemented information generated from the household surveys, focused group discussion and interviews.In order to minimise incidences of confusing agricultural crops to be natural vegetation, the satellite images used were taken in months of dry season (July and August) after harvesting seasons.

A shift from pastoralism to crop farming practices
The results from the household survey showed that land use practices around Lake Nakivale wetland had greatly changed from semi-nomadic and transhumant cattle keeping which used to be a dominant economic activity before 1994 (47% of land use) to crop farming (Figure 1), adversely affecting the wetland system and surrounding vegetation cover.The destruction of Lake Nakivale wetland was now widespread and intense.As more cattle grazing rangeland was converted to crop gardens, the cattle keeping activities were restricted either to small patches of isolated pasture land or marginal land such as flood plains, wetland fringes and steep slopes of surrounding hills that form catchment areas.
In terms of economic activities, about 62.5% of the respondents (n = 197) were actively engaged in crop cultivation alone while 19.7% of the respondents (n = 62) were practicing mixed farming that is, rearing of livestock and crop cultivation (Table 1).Only 1.3% of the respondents (n = 4) were practicing cattle keeping.Use of land to put up commercial shops was being practiced by 7.0% of the respondents (n = 22).About 4.8% of the respondents (n = 15) were not actively involved in any significant economic activity apart from being casual workers.Fisheries activities occupied 2.9% of the respondents (n = 9).The form of cattle keeping before 1994 was communal, semi-nomadic and transhumant in nature.This was confirmed by 60% of the respondents (n = 189) who indicated that although the cattle keepers had their homesteads around Lake Nakivale, depending on seasons, they used to move with their livestock from place to place even beyond Uganda's international borders to the United Republic of Tanzania in search of pasture (Table 2).
The comparison of land cover map of 1994 and 2011 revealed a great conversion of the former pastoralists' grazing rangeland into crop farmland.The grazing areas were reduced from approximately 12,120ha to merely 4,340ha (36%).On contrary, in the same period, the land under crop cultivation had increased from 120ha to more than 5,560ha (46.3 times) and wetland encroachment from zero to about 189ha (Figure 1).

Clearing of wetland forests and bush land
The crop growing community had increasingly and extensively cut down wetland forests, bush land and shrubs in order to open fresh land for subsistence crop cultivation.About 18.4% of respondents (n = 58) noted that deforestation was now one of the major threats to the conservation of Lake Nakivale wetland (Table 3).The forests and bush land on the fringes on Lake Nakivale wetland were indiscriminately converted to crop gardens.A total of 138 respondents (43.8%) ranked the level of deforestation high while 42 respondents (13.3%) put it medium level (Table 6).The trees and other woody materials that were cut down were either burnt into charcoal for commercial purposes or directly utilised as fuel wood.The rest of the plant residues and debris which would later improve soil fertility (humus) were being burnt to create a clear and open land for crop cultivation.Furthermore, two important historical and cultural forests of Ishanze and Kabeigarire where the former Kings and Queens of Ankole kingdom were respectively buried were completely destroyed.

Increased incidences of human-wildlife conflicts
In all sampled villages, residents indicated that due to the destruction of bush land and expansion of crop fields, incidences of human-wildlife conflicts had increased.In 12 out 15 villages (80%) hippopotamus was the main problem animal that was responsible for eating and destroying the crops.Leopard was mentioned in 5 villages (33.3%) as a key problem animal.It was accused of killing livestock, while Nile crocodile was considered as the most notorious and dangerous animal in 3 villages (20%).As to why the wild animals were increasingly becoming a problem to residents, three factors were mentioned namely, increased human settlement and crop cultivation in areas that were once wild animals' habitat and the proximity of Lake Mburo national park to their villages.

Use of agro-chemicals
Farmers were applying agro-chemicals on crops grown in and on the edge of Lake Nakivale in order to control crop pests and diseases.The application of agro-chemicals on crops like tomatoes was found to be common in 5 out of 15 sampled villages (33.3% of the villages).Unlike the application of pesticides to kill livestock ticks which was widespread but taking places outside the wetland, the use of chemicals on crops was being carried out in or on fringes of the wetland.

Human settlement on the fringes of wetland
The human settlement on the fringes of Lake Nakivale wetland increased in intensity and magnitude.The population of refugees from the Democratic Republic of Congo increased from 1,294 individuals in September, 2004 to 27,053 people in June, 2011 (1983% increase).The number of other refugees raised in the same period as follows; Burundians from 326 to 5,281, Eritreans from 0 to 1,286 and Ethiopians from 73 to 330.Similarly, population of Ugandans who illegally settled on the refugee resettlement land increased from 4,892 in 1994 to over 10,000 people in 2012 (Figure 2).About 82.4% of the homesteads which were situated within 400 metre strip along the shores of Lake Nakivale (n =574) had no proper human waste disposal facilities.The existing pit latrines were shallow, weak and potentially risky to human life as there was high potential of human wastes joining water system (pollution), causing waterborne diseases.The population exerted pressure on wetland resources.About 43.2% of the respondents (n = 136) ranked the level of human exploitation of wetland resources as a high threat while 21% (n = 66) put it at a medium level (Table 5).

Overgrazing
About 26% of the respondents (n = 82) were still keeping livestock.On average each respondent had 15 heads of cows and about 21 goats.This was much less than what they used to possess in 1990s which were in hundreds.
The life style of cattle keepers was no longer transhumant but sedentary in nature.However, they were confined in flood plains, wetlands and steep slopes of surrounding hills.These areas were overgrazed and signs of land and wetland degradation were evident (Plate 1).Deep gullies were observed in banana plantations in the lower slopes of Rwendama and Kigyende hills (Plate 2).Soils and earth materials from these gullies were finding their way into Lake Nakivale through erosion and runoffs.The gullies were beginning small and shallow on the upper part of banana plantation, thereafter, go deepening and widening further and further as water runoffs move down hill taking soils and crop residues.The assessment of gullies showed that all of them were following the natural water drainage system that leads to Lake Nakivale Wetland.The eroded soils were ending up in the wetland system.It was observed that crops within a distance of 10 metres from the gully appeared weaker and poorer than those that were far away from gullies.

Wetland encroachment
About 14% of the respondents (n = 44) had their gardens either in or on the edge of Lake Nakivale Wetland.Majority of them (88.6%) were nationals and the rest (11.4%) were refugees.All the respondents (n=315) said that the problem of wetland reclamation and conversion to crop fields did not exit at the time when the landscape was dominantly utilized by transhumant pastoralists for cattle keeping.They indicated that encroachment of the wetland intensified in late 1990s and early 2000s as a result of the scramble for land for food production.About 68.9% of the respondents (n = 217) indicated that wetland reclamation was now a serious threat to the conservation of Lake Nakivale Wetland (Table 3).However, 82.2% of the respondents (n = 259) ranked the level of wetland reclamation as high while 7% of the respondents put it at medium level (Table 4).It was established that by the end of 2011 approximately189ha of the wetland had been encroached.When the Landsat 7 Thematic Maper (TM) satellite images taken in July 1984, July 1999 and August 2010 and land cover map were analysed, it became clear that over a period of time, the wetland experienced human induced degradation.It was most damaging threat that with time, was like wipe out the whole wetland system (Figure 3).Areas which were heavily degraded include fringes of Lake Nakivale Wetland, some sections of River Rwizi banks, as it Plate 1.Some section of hilly areas around lake Nakivale Wetland which have been heavily degraded by overgrazing.
Plate 2: Deep gullies in a banana plantation on the slopes of Rwendama hill: eroded soils are deposited in Lake Nakivale wetland.
approaches Lake Mburo-Nakivale wetland system and islands on Lake Nakivale.

Increased commercial centres and other infrastructure development
The commercial centres around Lake Nakivale Wetland have over the last two decades had increased in number, size and quality.They increased from three in 1994 to over 15 in 2012, with Isingiro Town which according to respondents is believed to have had a few shops, growing into a major town council.A rural road network was constructed to improve accessibility to remote areas, ease transportation of agricultural produce such as beans, maize and banana to urban markets and expedite the general service delivery to the increased population.However, it was established that poor drainage system in some sections of feeder roads had contributed to the siltation of Lake Nakivale as earth materials eroded from these roads (Plate 3) were ending up in the water system.

DISCUSSION
The results of the study indicate that subsistence crop farming which replaced semi-nomadic and transhumant pastoralists' land use practices had emerged as a dominant economic activity and the greatest source of livelihoods for the neighbouring communities around Lake Nakivale Wetland.However, the traditional crop farming practices have had more disturbing and destructive effects on the wetland system than pastoralists' practices.This could be attributed to two major factors.One, pastoralists used to make strategic seasonal movements to allow sustainable utilization of pasture and other wetland resources thus conserving the rangeland (Simpkin, 2005).Second, crop farmers have destroyed natural vegetation cover at an alarming rate, encouraged wetland encroachment and exposed soils to erosion (Nunes et al., 2011;Sharm and Tiwari, 2010).The practice of burning crop residues and vegetation matter while preparing land for crop cultivation was a bad practice that did not only compromise the gradual Plate 3. Heavily degraded section of one of the feeder roads, earth materials eroded are deposited in the wetland.
recycling of soil nutrients but sometimes acted as a source of seasonal fires that burn Lake Nakivale Wetland system.
Although the national environment management regulations prohibit cultivation of crops within a 200 metre strip along the shores of Lake Nakivale wetland (protected zone) and empower the local government authorities to protect wetlands (GOU 1997;GOU, 2000), farmers who had planted banana, watermelon and cabbage within the wetland and protected zone.The causes of shift in land use practices around Lake Nakivale Wetland seem to be both by coincidence and as a government policy issue.By coincidence because when the Tutsi refugees (traditionally pastoralists) left the study area and returned to their motherland, Rwanda in 1994, they were replaced by the Hutu ethnic group who are crop cultivators.This created a drastic change in land use and land cover.It was also the government of Uganda and UNHCR's policy to make refugees self reliant and less dependent on relief items (Hunter, 2009).However, allocating land parcels to refugees to grow crops stimulated the influx of nationals in search of either free or cheap land for crop cultivation.Many nationals settled on the fringes of Lake Nakivale wetland as this was the only land that was perceived to be available for them as the rest of it was reserved for refugees.
The loss of natural vegetation cover in the study area can be attributed to the poor farming methods and land use practices involved in the crop production such as clearance of tree cover coupled with the use of fire to prepare land for crop production.This has led to the decimation of wetland forests, bush land and woodland which are critical habitat for wildlife.This explains why the remaining wild animals were increasingly becoming a source of conflict between wildlife managers and residents.The rapid loss of tree cover and the degradation of Lake Nakiale Wetland and adjacent landscape can also be associated with the exponential human population growth.For instance, the refugee population grew from 15,304 people as 30 th September, 2004 to 53,153 individuals as of 30 th June, 2011 which is 247.3% increase.In other words, within a period of just seven years, the population of refugees multiplied by 3.5 times.The population of nationals also doubled.The only decline in population was noted on Rwandese refugees (Figure 2).This was basically due to the fact that Rwanda government took an important step towards repatriation of her citizens who were refugees in neighbouring countries.The government in collaboration with UNHCR encouraged refugees of Rwanda origin to go back home as the country was now peaceful and stable.Many refugees responded positively and were repatriated during the time of this study.
The depletion of two important sacred forests of Ishangye and Kabeigarire that possess historical and cultural values could be attributed to the failure by the government of republic of Uganda to restore and support the institution of Ankole Kingdom.This has not only denied people who take pride in their history and culture a chance to protect their heritage but destroyed a vital tourism attraction.Developing the two sites into a tourist facility such as constructing a five star hotel or recreation facility that offers among other services such as a boat ride on Lake Nakivale, forest walk, cultural and historical interpretation and picnic beach facilities could easily promote tourism industry in Isingiro district.This would in turn, create jobs for the youth and attract private sector to invest in rural areas.At the long run, the local people would accrue economic benefits from cultural tourism which would act as incentives for them to conserve Lake Nakivale Wetland system.
Although the application of agrochemicals to crops is one of the modern ways of protecting crops against pests and diseases thus, improving yields, their use on crops grown in wetlands was likely to have a long term negative effect on the quality of water system and wildlife habitats.If the use of pesticides was not well regulated/controlled early enough, it would be potentially dangerous to human beings and aquatic species, as there were high chances of these chemicals to find their way to the water system.The threat of water pollution was also eminent because of human settlement on the edge of the wetland without proper housing and human waste disposal system.The conversion of livestock grazing areas into crop fields made it difficult for the remaining pastoralists to continue practicing transhumant lifestyle.The cattle keepers were forced to abandon their pastoralists' lifestyle and practices to adopt sedentary livestock management.They were squeezed out of cattle rangeland and confined in an "empty" land (Bagenda, et al., 2003), most of it being either flooded plains, wetlands and steep slopes of surrounding hills.
Consequently, overgrazing has become more rampant and widespread, accentuating the land degradation.The bare hills can no longer hold heavy water runoffs because they are devoid of grass and tree cover that would naturally control the speed of water runoffs.Soil and other earth materials are eroded uncontrollably leading to the development of deep gullies in banana plantations in the lower slopes.The deposition of earth materials into the wetland is considered to be one of the causes of current siltation and seasonal receding of Lake Nakivale (NAFIRRI, 2010).This situation was accentuated by overgrazing that takes place on the upper parts of the hill slopes, leaving the land bare.
The encroachment and reclamation of wetland was widespread in the southern part of the wetland where land is predominantly owned by the government of Uganda in collaboration with UNHCR as refugee settlement.The situation was quite different in the northern part of the wetland, where land was either owned by private farmers or Lake Mburo national park.This perhaps raises the critical issue of land tenure system and how it influences the land use practices and conservation of wetland resources.It appears, where farmers had the right to access, control and use the land, they were more responsible for the protection of wetland resources than where they were not sure of their future stay on land.This is possible because it has been noted that right to land is crucial in determining what role land plays in the livelihood of a household (Soini, 2006).The growth in urbanisation has had two major effects on Lake Nakivale wetland.First, residents of urban centres were depending on wetland for fuel wood, handcraft materials and fisheries resources.Second, the poor waste disposal system in urban centres which are built in boggy areas was a potential source of water pollution.

CONCLUSION
From the study, it can be concluded that, change in land use from traditional transhumant pastoralism to subsistence crop farming has accentuated human induced degradation of Lake Nakivale Wetland, a Ramsor site.Traditional crop farming, as a form of land use practice has negatively affected wetland system because it encourages direct clearance of natural vegetation cover and reclamation of the wetland.The loss of tree cover exposes soils to erosion leading to the siltation of Lake Nakivale and loss of soil fertility.It is also imperative that restoration of degraded areas and overall management of Lake Nakivale wetland should integrate issues of land use.Land use planning and formulation of general management plan of the wetland should also put into consideration trends in land use practices, if the integrity of the wetland system is to be enhanced.

Figure 1 .
Figure 1.Changes in land use practices around Lake Nakivale Wetland between January 1994 and December 2011

Table 1 .
Current land use in Lake Nakivale and adjacent landscape based on major economic activities.

Table 2 .
Form of cattle grazing during 1959 to 1994 period.

Table 3 .
Major threats to conservation of Lake Nakivale Wetland.

Table 4 .
Level of wetland reclamation as a threat to conservation of L. Nakivale Wetland system.Change in human population in Nakivale Refugee Settlement from 30 th September 2004 to 30 th June 2011 (Source: Regional Office of Prime Minister, Mbarara).

Table 5 .
Level of overexploitation of wetland resources.

Table 6 .
Level of deforestation.