Abstract:
In Ethiopia, wetland resources play a vital role in the lives of adjacent communities by helping them to
achieve food security and livelihoods. However, many wetlands throughout the country are facing degradation as high population growth rate increases the need for more fertile agricultural land. Lack of awareness
and logistic constraints are important reasons for the weak consideration of wetland ecosystems by the country's development planners. In this paper, we set out to develop methods for predicting species–environment
relationships. Decision tree models and Canonical Correspondence Analysis (CCA) were used to identify factors influencing macroinvertebrate community structure in natural wetlands of Southwest Ethiopia. The
models were based on a dataset of 109 samples collected from 57 sites located in eight different wetlands.
Sixteen macroinvertebrate taxa were selected based on their frequency of occurrence to determine the status
of the wetlands. It was found that Corixidae, Baetidae and Hydrophilidae had the highest predictive model
performance. This indicates that these taxa have clear requirements regarding their environmental conditions. The low Kappa value combined with the high number of Correctly Classified Instances of Chironomidae
may be related to their high frequency of occurrence, so that their presence is of little predictive power. This
was also further illustrated by the Canonical Correspondence Analysis (CCA) where the family of Chironomidae,
common at nearly every sampling station in the wetlands, was plotted in the centre of the CCA axis. Vegetation
cover, water depth, and conductivity were the most important variables determining the presence or absence of
macroinvertebrate taxa. These variables were selected in more than 80% of the classification tree models and
played a critical role in the ordination analyses. The sensitivity analysis, based on the regression tree models,
also showed that vegetation cover and conductivity were affecting the abundance of some macroinvertebrate
taxa. Information on habitat quality and environmental factors preserving a high diversity are essential to develop
conservation and management programs for wetlands and their related ecosystem services in Ethiopia, where
wetland resources are being lost at a high rate, and continue to be at high risk due to expansion of agricultural
and other development activities.
