Land health surveillance for identifying land constraints and targeting land management options in smallholder farming systems in Western Cameroon.

Abstract

Quantitative and up-to-date information on ecosystem characteristics and land health constraints are needed to understand land degradation trends and patterns, as well as formulating appropriate and specific interventions. A study was carried out in the Western Highlands of Cameroon using the Land Degradation Surveillance Framework (LDSF) to: (1) establish baseline measurements to monitor and assess land management impact and ecosystem health over time; (2) describe land health patterns in land uses and associated degradation; and (3) deduce implications and propose targets to engage with stakeholders to develop site-specific agroforestry and other sustainable land management interventions. The LDSF is a spatially stratified, random sampling design framework use to characterize sentinel sites consisting of 10 km×10 km blocks and clusters of 160 plots. This report provides preliminary analyses of the key factors that indicate the land and vegetation health of the Bamendjou sentinel site. These indicators provide a basis for assessing land degradation and productivity as well as the availability of key ecosystem services that are ecological functions and contribute to livelihoods improvement. The study identified and classified the indicators into ecological characteristics, soil physical and chemical indicators. It was observed that the site is dominated by mountainous relief which is as inappropriate for intensive and continuous cropping without conservation practices. Over 88% of the site (8800 ha) was under cultivation at the time of the survey implying that nearly every hectare of the land including the steepest slopes is cultivated. Majority of land of the site (>55%) has slope greater than 10% however, the soil erosion risk across the site was minimal. Trees and shrubs densities across the site were on average 143 tree ha^-1 and 192 shrub ha^-1, respectively. Though not significant, both shrub and tree densities were higher in cultivated as compared to uncultivated. The herbaceous cover rate across the entire site was found to be annual and was estimated to be between 15-40% for cultivated and between 40-65% for uncultivated lands. Textural analysis of the samples indicated that the soils have a high content of clay (75.64%). Infiltration was observed to be higher in cultivated than uncultivated lands. The estimated cluster-level frequencies of root depth restriction were 0.62 and 3.62% within the 0-20m and 0-50cm depth, respectively. A wide range was observed among values for SOC across the study site with significant differences in SOC concentration among land uses. The high proportions of lands of the study site are slightly acidic with pH ranging from 5.1-6.1 without any significant difference among land use. The findings of this study provide a set of indicators and attributes of land degradation for smallholder farmers and decision makers and form a basis for targeting specific agroforestry and other land management interventions that help in reversing the trends of land degradation.

Key words

• agroforestry
• clay fraction
• continuous cropping
• ecosystem services
• ecosystems
• erosion
• highlands
• infiltration
• intensive cropping
• land degradation
• land management
• land use
• livelihoods
• monitoring
• mountain areas
• organic carbon
• productivity
• relief
• shrubs
• slopes
• small farms
• soil chemical properties
• soil organic matter
• soil pH
• soil physical properties
• soil texture
• stakeholders
• sustainability
• trees
• vegetation
• woody plants