A general to specific approach for constructing composite business cycle indicators

Combining economic time series with the aim to obtain an indicator for business cycle analyses is an important issue for policy makers. In this area, econometric techniques usually rely on systems with either a small number of series, N, or, at the other extreme, a very large N. In this paper we propose tools to select the relevant business cycle indicators in a â mediumâ N framework, a situation that is likely to be the most frequent in empirical works. An example is provided by our empirical application, in which we study jointly the short-run co-movements of 24 European countries. We show, under not too restrictive conditions, that parsimonious single-equation models can be used to split a set of N countries in three groups. The first group comprises countries that share a synchronous common cycle, a non-synchronous common cycle is present among the countries of the second group, and the third group collects countries that exhibit idiosyncratic cycles. Moreover, we offer a method for constructing a composite coincident indicator that explicitly takes into account the existence of these various forms of short-run co-movements among variables

Assessing Conservation Values: Biodiversity and Endemicity in Tropical Land Use Systems

Despite an increasing amount of data on the effects of tropical land use on continental forest fauna and flora, it is debatable whether the choice of the indicator variables allows for a proper evaluation of the role of modified habitats in mitigating the global biodiversity crisis. While many single-taxon studies have highlighted that species with narrow geographic ranges especially suffer from habitat modification, there is no multi-taxa study available which consistently focuses on geographic range composition of the studied indicator groups. We compiled geographic range data for 180 bird, 119 butterfly, 204 tree and 219 understorey plant species sampled along a gradient of habitat modification ranging from near-primary forest through young secondary forest and agroforestry systems to annual crops in the southwestern lowlands of Cameroon. We found very similar patterns of declining species richness with increasing habitat modification between taxon-specific groups of similar geographic range categories. At the 8 km2 spatial level, estimated richness of endemic species declined in all groups by 21% (birds) to 91% (trees) from forests to annual crops, while estimated richness of widespread species increased by +101% (trees) to +275% (understorey plants), or remained stable (- 2%, butterflies). Even traditional agroforestry systems lost estimated endemic species richness by - 18% (birds) to - 90% (understorey plants). Endemic species richness of one taxon explained between 37% and 57% of others (positive correlations) and taxon-specific richness in widespread species explained up to 76% of variation in richness of endemic species (negative correlations). The key implication of this study is that the range size aspect is fundamental in assessments of conservation value via species inventory data from modified habitats. The study also suggests that even ecologically friendly agricultural matrices may be of much lower value for tropical conservation than indicated by mere biodiversity value

Distribution of phytoplanktonic parameters in the Indian sector of the Southern Ocean during Indigo III Cruise

The distribution of chlorophyll-a obtained by HPLC along vertical and horizontal profiles during Indigo I11 cruise in the Indian sector of the Southern Ocean was used to correlate the phytoplankton and watermasses patterns. They confirm that the Southern Ocean is not ecologically uniform as is implied by the general term "Antarctic and Subantarctic ecosystem" (Hempel,1985). Highest chlorophyll-a standing crops are associated with the main frontal systems (the Subtropical Convergence, the Antarctic Polar Front and the Antarctic Divergence), In these particular areas, significant amounts of living phytoplankton are found as far as 70 meters deep, suggesting a downwards transport of chlorophyll-a along isopycnals, in relation with the frontal hydrodynamics. In interfrontal areas, chlorophyll-a concentrations are generally very low and restricted to the upper layers of the water column. Therefore, the vertical distribution of phytoplankton in the Southern Ocean is not as uniform as expected, referring to El Sayed (1978) or to Jacques et Minas (1981) . These preliminar results show that a more intensive and detailed study of the Antarctic frontal systems might lead to a better understanding of the phytoplankton distribution and productivity