Litter N:P ratios indicate whether N or P limits the decomposability of graminoid leaf litter

The N:P ratio of leaf litter may determine if decomposability is N-limited (litter with low N:P ratio) or P-limited (litter with high N:P ratio). To test this hypothesis and to determine the threshold between N and P limitation, we studied relationships between litter N and P concentrations, litter mass loss and effects of fertilisation on litter mass loss in laboratory experiments. Leaf litter of 11 graminoid species was collected in Swiss and Dutch wetlands, yielding 84litter samples with a broad range of N and P concentrations (3.2-15.1mg N g−1, 0.04-1.93mg P g−1) and with N:P mass ratios ranging from 5 to 100. On nutrient-free sand, dry mass loss after five or ten weeks (5.5-53% of initial mass) correlated positively with the N and P concentrations of the litter. Within species, mass loss correlated mainly with N for litter with low N:P ratio, and with P for litter with high N:P ratio, in agreement with our hypothesis. Among species, however, these relationships did not exist, and decomposition rather correlated with the specific leaf area. When the litter was incubated on fertilised sand, 35 out of 50litter samples decomposed faster than on nutrient-free sand. Decomposition was generally accelerated by P fertilisation (i.e. P-limited) when the N:P ratio of the litter was above 25 and the P concentration below 0.22mg g−1, supporting our hypothesis. N-limited decomposition was not significantly related to the litter N:P ratio but occurred rarely for litter with N:P ratio greater than 25, and only for litter with N concentration below 11.3mg g−1. We conclude that the N:P ratio of leaf litter indicates whether its decomposability is more likely to be N- or P-limited. The critical N:P ratio (threshold between N and P limitation) appeared to be 25 for graminoid leaf litte

Income Inequality Decomposition, Russia 1992-2002: Method and Application

Decomposition methods for income inequality measures, such as the Gini index and the members of the Generalised Entropy family, are widely applied. Most methods decompose income inequality into a between (explained) and a within (unexplained) part, according to two or more population subgroups or income sources. In this article, we use a regression analysis for a lognormal distribution of personal income, modelling both the mean and the variance, decomposing the variance as a measure of income inequality, and apply the method to survey data from Russia spanning the first decade of market transition (1992-2002). For the first years of the transition, only a small part of the income inequality could be explained. Thereafter, between 1996 and 1999, a larger part (up to 40%) could be explained, and ‘winner’ and ‘loser’ categories of the transition could be spotted. Moving to the upper end of the income distribution, the self-employed won from the transition. The unemployed were among the losers

Реакція української інтелігенції на Голокост: моделі ситуативної поведінки

The article regards the types of behawor attitude of the Ukranian intellegensy to the Holocaust, which was realigeb by nazi on the Kiev region

Earthworm abundance and availability does not influence the reproductive decisions of black-tailed godwits in an agricultural grassland

Maintaining the biodiversity of agricultural ecosystems has become a global imperative. Across Europe, species that occupy agricultural grasslands, such as black-tailed godwits (Limosa limosa limosa), have undergone steep population declines. In this context, there is a significant need to both determine the root causes of these declines and identify actions that will promote biodiversity while supporting the livelihoods of farmers. Food availability, and specifically earthworm abundance (Lumbricidae), during the pre-breeding period has often been suggested as a potential driver of godwit population declines. Previous studies have recommended increasing the application of nitrogen to agricultural grasslands to enhance earthworm populations and aid agricultural production. Here we test whether food availability during the pre-breeding period affects when and where godwits breed. Using large-scale surveys of food availability, a long-term mark-recapture study, focal observations of foraging female godwits, and tracking devices that monitored godwit movements, we found little evidence of a relationship between earthworm abundance and the timing of godwit reproductive efforts or the density of breeding godwits. Furthermore, we found that the soils of intensively managed agricultural grasslands may frequently be too dry for godwits to forage for those earthworms that are present. The increased application of nitrogen to agricultural grasslands will therefore likely have no positive effect on godwit populations. Instead, management efforts should focus on increasing the botanical diversity of agricultural grasslands, facilitating conditions that prevent hardening soils, and reducing the populations of generalist predators. </ol

Decompositie van inkomensongelijkheid: Rusland 1992-2002

Introductie: Economen en sociale wetenschappers gebruiken kerngetallen om de inkomensongelijkheid van landen te beschrijven. In de meeste studies worden de Gini index, de leden van de “Generaliz Entropy” familie van indices (zoals de Theil en Atkinson coëfficiënten en de “Mean Logarithmic Deviation”), en de percentielratio’s P90/P10 en P75/P25 gebruikt. De waarden van al deze coëfficiënten vertellen iets over de inkomensongelijkheid op een bepaald moment of, via een tijdreeks van coëfficiënten, over trends in de inkomensongelijkheid. Een van de centrale vragen bij de bestudering van inkomensongelijkheid betreft die naar de onderliggende factoren. Decompositie van inkomensongelijkheid kan daar op een antwoord geven. Decompositie van inkomensongelijkheid naar subgroepen in de populatie of naar bronnen van inkomen werd in het begin van de jaren ’80 geïntroduceerd in publicaties van Bourguignon (1979) en Shorrocks (1980; 1982; 1984). Zij lieten zien dat een aantal, maar niet alle maten voor ongelijkheid additief kunnen worden gedecomponeerd. Sinds die tijd is een groot aantal sociaal-economische studies met deze (inmiddels) standaard toepassingen verschenen...