The establishment of enclosures has become an important measure to combat land degradation in many of the world’s semi-arid rangelands. In view of the increased pressure exerted by this land reclamation strategy on the neighbouring agricultural lands, knowledge of the time required for restoring vegetation cover and soil health, and of the potential positive impact of an adapted management strategy, is highly required. This paper assesses the vegetation and soil rehabilitation in a 23-year chronosequence of two different enclosure management types. In the severely degraded, semi-arid Njemps Flats plain of the Lake Baringo Basin in Kenya communal enclosures characterised by high quality inputs and strict control, and private enclosures managed by individual farmers, were installed since the 1980s. Six communal enclosures (3-17 years since establishment) and six private enclosures (13-23 years since establishment) were selected. Vegetation cover was estimated along three 50 m transects set within each enclosure and in the adjacent open grazing area using the point-to-line transect method. Five 0.5 m2 quadrats systematically placed alongside each transect were sampled for herbaceous standing biomass and topsoil physical, chemical and biological analyses. Grass cover and herbaceous biomass production proved to be the most responsive biotic parameters under both management types, whereas the recovery of the forbs was unsuccessful. Under communal management, the biomass production fully recovered up to its optimal level as recorded in the neighbouring nature reserves. Within private enclosures however, the adopted management strategies seriously restricted biomass production to a significantly lower level. Soil quality generally recovered more slowly with time. Significant improvements compared to the open rangeland were recorded in topsoil bulk density, organic C and total N stocks, and microbial biomass C and N stocks of the communal enclosures. Unlike the communal enclosures, only topsoil bulk density and the microbial biomass C stock showed a significant difference in the private enclosures. With respect to C and total N stocks, and the microbial biomass N a non-significant improving trend was recorded. The level of chemical and biological soil quality obtained under both management types is still low and draws the attention to the importance of careful monitoring of grazing and grass cutting activities under both enclosure management strategies. The chronosequences further highlight the potential of some well-managed private enclosures, whereas intrinsic soil properties such as high alkalinity, as well as changes in management, limit the rehabilitation of some other private as well as communal enclosures.
INT-2 The private enclosures, reseeded and managed by individual farmers with limited financial and technical means, are much smaller, with sizes smaller than 1 ha. Fencing is done using cut thorn bushes (Acacia and Prosopis sp.) and/or planted thorn cactus (Opuntia sp.).
Climate change impacts | Effect of Nbs on CCI | Effect measures |
---|---|---|
Biomass cover loss | Positive | Biomass cover loss: dry herbaceous biomass production (Kg/ha), grass/forbs/sedges (% of total vegetation), Bare ground (%), litter (%), vascular plant seedlings (%) |
Loss of food production | Positive | Productivity: dry herbaceous biomass production (Kg/ha), grass/forbs/sedges (% of total vegetation) |
Reduced soil quality | Positive | Soil quality: 1. Physical fertility = sand/silt/clay (%). 2. Chemical fertility = bulk density, pH, CaCO3, electrical conductivity, exchangeable sodium percentage, Organic C (g/m), total N. 3. Biological fertility = microbial biomass N & C (g/m) |
The Njemps Flats range unit is located between 18450 and 08150 northern latitude and 358450 and 368300 eastern longitude in the Baringo District of the Eastern Rift Valley in Kenya
INT-1 Communal enclosures, varying in size from 6 to 140 ha, are perimeter fenced using a solar-powered electric fence. After clearing of much of the existing undesirable vegetation, the land is prepared for planting by the construction of micro-catchments. A mixture of drought-resistant trees and grasses, such as the fast- growing exotic Prosopis and Leucaena tree species and the indigenous grasses Cenchrus ciliaris, Enteropogon macrostachyus and Eragrostis superba, have been selected for planting and seeding.
Climate change impacts | Effect of Nbs on CCI | Effect measures |
---|---|---|
Loss of food production | Positive | Productivity: dry herbaceous biomass production (Kg/ha), grass/forbs/sedges (% of total vegetation) |
Biomass cover loss | Positive | Biomass cover loss: dry herbaceous biomass production (Kg/ha), grass/forbs/sedges (% of total vegetation), Bare ground (%), litter (%), vascular plant seedlings (%) |
Reduced soil quality | Positive | Soil quality: 1. Physical fertility = sand/silt/clay (%). 2. Chemical fertility = bulk density, pH, CaCO3, electrical conductivity, exchangeable sodium percentage, Organic C (g/m), total N. 3. Biological fertility = microbial biomass N & C (g/m) |
The Njemps Flats range unit is located between 18450 and 08150 northern latitude and 358450 and 368300 eastern longitude in the Baringo District of the Eastern Rift Valley in Kenya