Soil surface disturbances in cold deserts: effects on nitrogenase activity in cyanobacterial-lichen soil crusts

Cyanobacterial-lichen soil crusts can be a dominant source of nitrogen for cold-desert ecosystems. Effects of surface disturbance from footprints, bike and vehicle tracks on the nitrogenase activity in these crusts was investigated. Surface disturbances reduced nitrogenase activity by 30–100%. Crusts dominated by the cyanobacterium Microcoleus vaginatus on sandy soils were the most susceptible to disruption; crusts on gypsiferous soils were the least susceptible. Crusts where the soil lichen Collema tenax was present showed less immediate effects; however, nitrogenase activity still declined over time. Levels of nitrogenase activity reduction were affected by the degree of soil disruption and whether sites were dominated by cyanobacteria with or without heterocysts. Consequently, anthropogenic surface disturbances may have serious implications for nitrogen budgets in these ecosystems.     

An investigation of the potential existence of ``food deserts' in rural and urban areas of Northern Ireland

Food Deserts have recently beenidentified in the United Kingdom. They havebeen defined by Tessa Jowell, UK GovernmentHealth Minister, as an area ``where people donot have easy access to healthy, fresh foods,particularly if they are poor and have limitedmobility.' The above definition is particularlyrelevant in Northern Ireland, where it isestimated that 32% of households do not haveeasy access to a car and it is recognized thatcertain groups in Northern Ireland are amongstthe poorest consumers in the United Kingdom.The phenomenon has been further exacerbated bythe effect of large grocery retailers locatingon the periphery of towns and the subsequentdisplacement effect of independent retailers inthe town center. The resultant effect is suchthat disadvantaged consumers cannot accessfresh, quality, nutritious foods at anaffordable price. Preliminary researchindicates that certain consumer groups areexcluded from equitable shopping provision –possibly to the detriment of their healthstatus. Research methodology includes aconsumer questionnaire, consumer focus groups,interviews, and comparative shopping exercisesthat confirm an inability among vulnerableconsumer groups to achieve an affordable,healthy diet. This was further complicated bynon-car owners' and lower-income family unitsneeding to shop locally and more frequentlythan their higher-income, car-ownercounterparts. This was demonstrated with theuse of shopping diaries. Future research to beconducted includes a large-scale survey acrossNorthern Ireland to ascertain accessibility,availability, and affordability of qualityfresh foods and to distinguish the consumergroups who are most vulnerable.