WP1: Desertification and degradation processes
The main objective of WP 1 is to increase the understanding of how degradation and desertification processes affect plant diversity and plant species distribution patterns in West Africa. This main objective encompasses three objectives.
Objective 1.1. a set of 8 relevant spatial and 29 relevant plot-based indicators was derived that can be effectively used in West Africa to assess desertification/degradation processes and their impact on plant distribution and diversity patterns. Most of the indicators can be applied at low costs. The potential of each indicator to determine the causes of desertification/degradation processes and the consequences on plant distribution and diversity patterns was tested by advanced statistical analyses and novel models. The meaning, range and application of each indicator are expounded in the UNDESERT List of Indicators of Desertification and Degradation available via the UNDESERT DSS.
Objective 1.2. was to set up models to analyze the cause and effect relationships between degradation processes and plant species and diversity patterns. To adequately assess and analyze these complex relationships a systematic approach of studies at different spatial and temporal scales considering specific local conditions as well as the entire Sahelo-Sudanian climatic gradient was set up. The studies sites are representative for the different climatic, soil and land use gradients prevailing in the Sahelian and Sudanian zones of the UNDESERT countries. Species distribution models (SDM), the Genetic Algorithm for Rule Set Production (GARP), One-Class Support Vector Machines (SVM), Generalized Linear Model (GLM) and the Multinomial Logit Model were applied. Results show amongst others that future climate changes are predicted to affect more negatively the Sudanian than the Sahelian flora. Comparing the weight of the factors climate and land use change for species patterns/diversity respectively, climate change proved to be more important than land use.
Objective 1.3 was to establish an ecological risk assessment to investigate the influence of land use and climate change on plant species distribution and diversity patterns.
Altogether six risk assessment case studies were conducted in the UNDESERT study sites representative for different climatic zones and spatial scales.
At local scale we investigated the risks of a) present land use and b) future land use for plant species and diversity patterns.
At national scale the risks of c) future climate change and the combined factors d) future land use and future climate change on plant species and diversity patterns were assessed. Advanced species distribution models (SDM), specifically regression models (GLM, GAM), machine learning models (ANN, GBM), classification models (CTA, MDA) and a maximum entropy model (Maxent) were calibrated to estimate the magnitude and probability of risks of changes in plant species distributions and diversity loss in relation to land use and climate changes.
Our results for the national scale reveal that both factors land use and climate pose high risks for plant species distribution and diversity patterns, being climate change the more significant one. In regard to present land use in the Sudanian zone adult individuals and juveniles of useful woody species often respond differently. The risk can be characterized as follows: Human activities influence negatively the diversity of juveniles of useful woody species. The risk of future land use (investigated in the North-Sudanian zone) consists in high probabilities that forest, woodland and tree savanna will transform into degraded savanna and farmland resulting in a concomitant loss of near natural vegetation. Future climate and future land use changes combined show a serious risk for the diversity patterns of highly valued woody species in Burkina Faso. The most diverse patterns of highly valued woody species for nutrition purposes are presently found in the southern parts of the North-Sudanian zone. By 2050 this zone will face a severe diversity loss and the highest species diversity is then predicted to occur in the transition zone between the North-Sudanian and South-Sahelian zone. Evaluating the risks of climate and land use change, climate change will affect the future diversity patterns of these highly valued woody species more seriously than land use change. These findings enable an improved understanding of the complex processes of plant distribution and diversity patterns in relation to land use and climate change. They were integrated by different data sets into the decision support system to facilitate sound environmental decision making.
Undesertworks to create an improved understanding of the effects of desertification and degradation processes in West Africa and to develop and implement best practices, such as carbon forestry, in close collaboration between scientists and local communities.
Financed by EU-FP7.