The water–food–energy nexus: an introduction to nexus concepts and some conceptual and operational problems

This introduction sets the scene for the special issue compiled by Martin Keulertz, Eckart Woertz and Tony Allan.     

Identification of Argentinian saline drylands suitable for growing Salicornia bigelovii for bioenergy

Salicornia bigelovii is an oilseed halophyte species that can be grown using saltwater in saline and coastal areas where conventional crops cannot be grown. Due to its high oil content, comparable with commercial crops, is a promising feedstock for biodiesel production. To determine the agroclimatic zoning of S. bigelovii in Argentina, thermal and rainfall indexes from its center of origin were taken into account and plotted for the period 1981–2010. The overlapping of the temperature and rainfall maps defined the agroclimatic zoning which determined optimal, very suitable, suitable, marginal and non-suitable areas for cultivation of S. bigelovii in Argentina. Subsequently, the Dryland Salinity classification of FAO was used to identify putative sites of implantation of S. bigelovii in moderately and strongly saline phases where soil electrical conductivity ranges from 12.4 to 22.1 mmhos/cm. Finally, the overlapping of both the agroclimatic suitability and Dryland Salinity maps afforded the agro-ecological suitability map, which showed the same five fitness classes defined in the agroclimatic zoning.     

Dryland lakes1

Dry regions of the world, that is, hyper‐arid to subhumid regions that are mostly warm to hot and so‐called ‘drylands’, cover almost 50% of the total land area. They are inhabited by human populations that are approaching one billion worldwide. Despite low rainfall levels, dry regions have some of the world’s largest lakes and reservoirs. They also have the widest variety of standing water types that include permanent freshwater lakes and reservoirs, temporary freshwater lakes, and permanent and temporary saline lakes. Many characteristics of these waters are different from waters in temperate, better‐watered areas, upon which most limnological knowledge is based. Notwithstanding many economic, scientific, ecological and other values, lakes in drylands are subject to extensive and intensive anthropogenic impacts. Included are almost all those affecting lakes in temperate, tropical and subtropical regions, as well as some impacts more or less confined to dryland lakes, especially salinization. These anthropogenic impacts and their importance have not been fully recognized at national and international levels.