SPATIAL PATTERNS OF LAND USE CHANGE
SPATIAL PATTERNS OF LAND USE CHANGE
- 1. Introduction
Similar partial patterns of land use have occurred across the research sites in east Africa over the pastor 50 years, characterized by increasingly intensively managed landscape outside of protected areas or extremely marginal environments. This general pattern has occurred at a very uneven pace across the region depending on historical conditions and varying driving forces. The most important land use conversions can be summarized as follows:-
- An expansion of cropping into grazing areas, particularly in the semi-arid to sub-humid areas.
- An expansion of rainfed and irrigated agriculture in wetlands or along streamed especially in semi-arid areas,
- A reduction in size of many woodlands and forests on land that is not protected
- An intensification of land use in areas already under crops in the more humid areas , and
- The maintenance of natural vegetation in most protected areas.
Perhaps less land use important from a geographical size standpoint, the main secondary towns in the study sites also grew rapidly. Their relatively small size belies their economic role in rural households and the impact of off and non farm activities in rural land and land management.
This main land use will be examined across the study sites, organized first by changes occurring in the semi-arid to sub-humid areas, and then those in the humid areas. Rural land use systems in East Africa, including pastoralism, agro-pastoralism and agriculture, have in the past been roughly associated with particular agro -ecological zones and particular groups of people. Change in where these land use systems are located and in who is conducting the activities is the story behind the large land use conversions in the region.
- 2. The semi-aid to sub-humid areas: these expansions of crops into grazing areas.
a) The spatial pattern of land use change
The largest conversion of land use in the study sties was the expansion of rainfed agriculture at the expense of grazing land in sub-humid and semi-arid areas. Between 1887 and 1950, semi-arid and sub-humid areas were predominantly pastoral with scattered settlement and cultivation. From the 1950s to the present there has been significant transformation of grazing land to crop land, a transformation experienced in all the study sites. The rate of expansion appears to be slowing in many areas (e.g. around Mt. Kilimanjaro on both the Kenya and Tanzania sides, and on the eastern slopes of Mt. Kenya) where the frontier of conversion is now in drought-prone land, but in other sites (e.g. Uganda sites) the expansion of agriculture had either not yet slowed, or the conversion had not yet occurred ( the predominantly pastoral sites of Sango Bay And Kabala/Ntungamo).
The conversion was usually an extension of cultivation from previously more humid areas into adjacent, if drier lands. With each succeeding period examined, the land under cultivation spread into increasing marginal land. In a few study sites where land ownership or social access to land was altered, in-migrants or large scale land users came to farm inside the rangelands forming islands of cultivation.
In our study sites on the slopes of Mt. Kilimanjaro and Mt. Kenya, the spatial pattern has been an expansion of rainfed agriculture down the agro-ecological gradient, from the high elevation, high potential(Cooler ,wetter) zones progressively into the lower potential(hotter, drier))zones. This expansion of cultivation down slopes formed land use change “rings” around the mountains that expanded outwards with each time period examined (Map 1 to 4). Both small holders and large scale enterprises played a part.
Statistically speaking, 13% of the land use in the Mt. Kilimanjaro /Kenya site changed between 1973 and 2000- almost all a conversion from rangeland (99% of the loss) to rainfed agriculture (80%) or to irrigated agriculture(20%). The conversion rate slowed with the earliest period of 1973 to 1984 having the most rapid conversion (Map 2) (Campbell, Lusch et al 20004) on the southern
- 3. Expansion of agriculture in wetlands and along streams in semi-arid areas.
Prior to the 20th Century the semi-arid lands of each of the tree countries were the domain of wildlife and livestock herders. Land management by herders allowed for access t water and grazing for both livestock and wildlife. The wetlands represented secure sources of water during annual season(s) and particularly during recurrent droughts. The productivity of vast areas of semi-arid land depended upon access of wildlife and livestock to these small perennial sources of water.
The case studies along altitudinal gradients in Tanzania ad Kenya show that over the past 75 years, and particularly the past 30 years, demands have increased for access to these lowland water resources from farmers practicing irrigated cultivation of high value crops, such as horticulture , rice and flowers. Farmers have migrated to these wetter margins of the rangelands in response to a shortage of land in areas of higher potential rainfed agriculture and to market opportunities. In some cases the irrigation is under an informal smallholders system (Lokitakitok, lower Moshi), in others it is by medium landowners (Mt. Kenya), while others it is organized under a scheme sponsored by a state organization or other institution( the Japanese rice project , the Tanganyika Planting Company(TPC) sugarcane plantation and the National Food Company (NAFCO) farm in lower Moshi Tanzania and the Mwea Rice Scheme below Mt. Kenya. More recently immigrant farmers have been joined by herders who have diversified their economy to include crop production, often in response to the impact of drought or of the decreased access of livestock to the water in swamps and rivers. Wildlife has experienced a similar decline in access to water.
The amount of land under irrigation has grown rapidly. In Kilimanjaro/ Kenya site, for example, irrigated land expanded from 245 to 4768 between 1973 and 2000, and in the Kilimanjaro /Tanzania site from 336 to 4078 hectares during the same period. The source of the water is usually rivers or swamps except for the sugarcane plantation in Kilimanjaro/Tanzania, which uses water being pumped from aquifers. Rice, flowers and vegetables are the main crops, though sugarcane is grown in Mr. Kilimanjaro/Tanzania. The crops are destined for both national and export markets.
In Uganda the case studies illustrates a “horizontal gradient” where wetlands are found in river valleys, the borders of lakes and as swamps within semi-arid lowlands. The importance of such sources to the livelihood systems within which they are located is similar to that found along the altitudinal gradients, they offer both water grazing, as is the competition between land uses for access to water.
The presence of wetlands has allowed the economy of the semi-arid lands to diversify to include herding, wildlife and associated tourism and irrigated agriculture. Each depends upon access to water, and while the land management practices of herders in the past allowed for wildlife, the addition and expansion of agriculture had resulted in increased competition over access to water between and among the three uses.
Although small in land area, thee activities have become important sources of income particularly for those who have ownership rights over the land or water. The vegetables and fruit produced with irrigation draws high prices in the national and international markets. Access to that water, however, is also becoming an increasingly important source of conflict between farmers and cattle and wildlife led the streams and swamps to be contested key resources even before those same resources were used for irrigation.
The patterns of land use change exemplified by these case studies is representative of similar areas elsewhere in east Africa , for example the Turkwel River in Kenya, the Ruaha River Basin in Tanzania and the Karamoja region in Uganda.
- 4. Reduction of Woodlands and forests outside of protected areas.
Many woodlands and forests without enforced protected areas have been reduced in size and /or their vegetative over has diminished. They have either been converted to pasture for grazing too fields for rainfed agriculture, or their woody plants have been extremely cut for charcoal production(Mbonile et al 2003;Oslo et al 2004)(Map 4).
The Mt. Kenya site illustrates the changes. Small hills in the semi-arid zone at the foot of the mountain were mostly covered by woody savannah or woodlands in the 1950s and even into the 1970s. The expansion of cultivation in the zone occurred these hills, leaving that did not have government status as reserves were being intensively used for wood fuel collection, charcoal production and grazing , and they were classed during land cover interpretation as degraded woodlands or as mixed bush/cultivation. Some of the hills still have in contrast , intact woodlands or forest because the surrounding communities have strongly protected them as sacred groves.
- 5. Intensification of cultivation in humid zones
In areas that were already cultivated in the 1950s, land use changes have been less dramatic. They have been primarily an in-filling of cultivation into valleys, hills and other pieces of land that had not yet been cropped, changed in types of crops, fragmentation and shrinkage of farms and (although this was not measured in our analysis) am increase in planted trees in densely populated areas. These changes have been primarily associated with intensification of the existing farming system, reflecting an increase in the application of Labour and in most places, capital inputs on the land.
The general pattern of land use change in the higher elevation or more humid areas is one of early settlement and cultivation, and of later intensification of cultivation. These regions in general have high agricultural potential, and this has shaped how they have developed. The general pattern has been.
- Early clearance of the forest grazing domestic animals and for shifting cultivation. The land cover reflected the patchwork mixture of remnants of forest, riverain woodlands, grassland covered hills and small fields.
- Gradual conversion to crops as cultivation expanded s population densities rose from the 1940s
- Conversion of the remaining pastureland to permanently cropped fields, and a switch from clan-based land holding to individual family farms. Perennial crops, such as bananas, trees, coffee and tea dominated the landscape.
- Livestock systems changed as animals were tethered or placed in paddocks and fed cut fodder planted on the farm from the drier zones. Dairy cows replaced meat cattle, and the size of the goat/sheep herds shrunk. The manure was placed on the fields.
- Continued intensification, including of use manure, soil conversation and chemical fertilizers and pesticides.
- Governments and other large scale land users have converted some land to commercial often export, crops.
The current trend is one of changing crop choice and related land management as markets and prices evolve and labour availability changes with out-migration and in-migration and income diversification. For example, the amount of land under coffee has diminished as coffee prices have declined and been replaced by horticultural crops sold nationally or internationally. Bananas are becoming a commercial crop for the market in large Tanzania cities, including Dar es Salaam. On the Kenya side of Mr. Kilimanjaro, the maize/beans farming systems continues to dominate though there re reports of declining soil fertility, increasing use of fallow and change crops that are less demanding of soil nutrients such as sweet potatoes and millet. In Sango Bay, Uganda the coffee/banana system remains but with reported declining soil fertility.
- 6. Some protected areas remain intact others not
Protected areas such as parks and reserves have, for the most part, remained intact. Protected constitute a large percentage of the land-12% in Kenya, 26% in Uganda, and 40% in Tanzania. The land cover within protected areas and the other mandated lands is often the most stable in the region. The exceptions have protected areas and the other government has changed the boundaries of a protected area, during periods of civil strife, or where a government has changed enforcement of deforestation rules. In Uganda, for example, some reserve land have been degazetted to legalize existing or permit new settlement, but wetlands gained enforced protected status (Mugisha 2002). In a section of lower Mt. Kenya forest, government representatives temporarily permitted forest clearance and cultivation (Oslo et al 2004)
The Shamba System, a mixed cultivation/tree plantation system established by colonial administration, is a special land use within protected forests. It has been expanded in some places but shrunk in others. Much of natural forest on the Tanzania side of Mt. Kilimanjaro (the eastern and northern slopes) has recently been replaced by Shamba System tree planting and crops. Forest villages are expanding while the land under crops is slowly replacing land under planted trees. Either no tree replanting is taking place or, if planted, the trees do not survive. In contrast, the Kenya government evicted villages cultivating Shamba System fields on Mt. Kenya in 2003, but it may change policies again to permit the villagers to return.
Despite the generally intact status of vegetation within protected areas in the past 20 to 30 years cultivation has extended to their borders and abrupt transition between natural vegetation for wildlife and cultivation and settlement. Since wildlife are common outside parks and are protected there, several sites experienced human-wildlife conflict with wildlife destroying crops and harming people. The expansion of agricultural settlements between protected areas and to protected area borders has also reduced wildlife access to grazing and water resources and reduced or blocked wildlife migration corridors. Wildlife and tourists that they draw, however, can be a source of income for some. In the Mt. Kilimanjaro/Kenya site, a savannah land with a swamp has been partially fenced and privately developed with tourist’s lodges.