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Traditionally, economists measure middle class from the income perspective. Considering quality of data for many African countries, relying solely on income may, unfortunately, lead to an incorrect picture. This article compares and analyses the African middle class measured by income and by ownership of assets. Results indicate that middle class sizes differ significantly in some countries, while in others they are more or less the same. Regression analyses performed to investigate potential correlates of the African income and assets middle class sizes indicate that the African assets middle class size is positively associated with income per capita and negatively with assets inequality. To a lesser extent, it is positively affected by education and negatively by ethnic fractionalisation. The African income middle class size depends positively on income per capita and education, while negatively on income inequality.

The retention forestry approach is considered as one of the potentially effective tools for sustainable forest management for conservation of biodiversity in managed temperate and boreal forests. Retention of old-growth forest structures (e.g., very large old living trees) in forest stands during clear-cutting provides maintenance of key habitats for many old-growth forest interior-species. Most of ecological studies on green tree retention (GTR) consequences for biodiversity have been focused on birds. However, the long-term studies of GTR impacts on forest birds are very poor. In this paper, we focused on assessment of the long-term consequences of leaving legacy oak trees on the cut areas for bird diversity 18–22 years after clear-cutting in managed temperate European hardwood floodplain forests. Results based on bird counting using mapping of bird nesting territories revealed a key importance of legacy oak trees for maintaining bird diversity in the study area. These results are widely applicable for managed temperate hardwood forests with serious dominance of oak (Quercus sp.) in forest stands. Legacy oak trees in this habitat type are keystone structures for bird diversity. Retention approach focused on these trees is potentially an important conservation tool for preserving forest bird diversity and other associated species in temperate hardwood forests managed by clear-cutting.

The paper examines the issue of weights and importance in composite indices of development. Building a composite index involves several steps, one of them being the weighting of variables. The nominal weight assigned to a variable often differs from the degree to which the variable affects the scores of the overall index. The newly suggested notion of importance is based on the idea that an important indicator, if omitted from the index, causes large changes in countries' results. We propose a method of measuring the importance and apply it to inequality variables in composite indices of development. The results show a low importance for most inequality variables, and for some of them, a large discrepancy between the nominal weights and the importance. We argue that the importance of variables should be considered in the process of index construction. This may imply a modification of the index when there is a large discrepancy between the nominal weights and importance and when the importance of some variables is extremely low. Whether any such modification is justified must be decided within the context of the particular index.

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