Gross and net nitrogen transformation rates and availability in late summer in tall shrub and birch hummock ecosystems of the Canadian low Arctic

Climate change is occurring most rapidly in the Arctic where warming has been twice as fast as the rest of the globe over the last few decades. Arctic soils contain a vast store of carbon and warmer arctic soils may mediate current atmospheric CO2 concentrations and global warming trends. Warmer soils could increase nutrient availability to plants, leading to increased primary production and sequestration of CO2. Presumably because of these effects of warming on shrub ecosystems, shrubs have been expanding across the arctic over the last 50 years, Arctic shrub expansion may track or cause changes in nutrient cycling and availability that favour growth of larger, denser shrubs. This study aimed at measuring gross and net nitrogen cycling rates, major soil nitrogen and carbon pool sizes, and elucidating controls on nutrient cycling and availability between a mesic birch (Betula nana) hummock tundra ecosystem and an ecosystem of dense, tall, birch (B. nana) shrubs. Nitrogen cycling and availability was enhanced at the tall shrub ecosystem compared to the birch hummock ecosystem. Net nitrogen immobilization by microbes was approximately threefold greater at the tall shrub ecosystem. This was in part because of larger microbial biomass nitrogen and carbon (interpreted as a larger microbial community) at the tall shrub ecosystem. Nitrogen inputs via litter were significantly larger at the tall shrub ecosystem and were hypothesized to be the major contributor to the higher dissolved organic and inorganic nitrogen pools in the soil at the tall shrub ecosystem. The results from this study suggest a positive feedback mechanism between litter nitrogen inputs and the enhancement of nitrogen cycling and availability as a driver of shrub expansion across the Arctic.

CONSTITUTIONAL JUSTICE IN AFRICA: An Examination of Constitutional Positivism, Fundamental Law and Rights in Ghana and Nigeria

This work explores the idea of constitutional justice in Africa with a focus on constitutional interpretation in Ghana and Nigeria. The objective is to develop a theory of constitutional interpretation based upon a conception of law that allows the existing constitutions of Ghana and Nigeria to be construed by the courts as law in a manner that best serves the collective wellbeing of the people. The project involves an examination of both legal theory and substantive constitutional law. The theoretical argument will be applied to show how a proper understanding of the ideals of the rule of law and constitutionalism in Ghana and Nigeria necessitate the conclusion that socio-economic rights in those countries are constitutionally protected and judicially enforceable. The thesis argues that this conclusion follows from a general claim that constitutions should represent a ‘fundamental law’ and must be construed as an aspirational moral ideal for the common good of the people. The argument is essentially about the inherent character of ‘legality’ or the ‘rule of law.’ It weaves together ideas developed by Lon Fuller, Ronald Dworkin, T.R.S. Allan and David Dyzenhaus, as well as the strand of common law constitutionalism associated with Sir Edward Coke, to develop a moral sense of ‘law’ that transcends the confines of positive or explicit law while remaining inherently ‘legal’ as opposed to purely moral or political. What emerges is an unwritten fundamental law of reason located between pure morality or natural law on the one hand and strict, explicit, or positive law on the other. It is argued that this fundamental law is, or should be, the basis of constitutional interpretation, especially in transitional democracies like Ghana and Nigeria, and that it grounds constitutional protection for socio-economic rights. Equipped with this theory of law, courts in developing African countries like Ghana and Nigeria will be in a better position to contribute towards developing a real sense of constitutional justice for Africa.