Does extreme environmental severity promote plant facilitation? An experimental field test in a subtropical coastal dune.

The stress gradient hypothesis (SGH) postulates how the balance between plant competition and facilitation shifts along environmental gradients. Early formulations of the SGH predicted that facilitation should increase monotonically with stress. However, a recent theoretical refinement of the SGH postulates stronger facilitation under moderate stress, followed by a decreasing role of facilitation in the most severe environments. We conducted field experiments along the most severe part of a coastal dune gradient in southeast Brazil to test the effect of stress on the intensity and importance of the net interactions between two tree species. First, we compared the performance of distinct life stages of Ternstroemia brasiliensis in the presence and absence of Guapira opposita adults along a beach-to-inland gradient, a gradient of environmental severity. To test the effect of one stress factor in particular, we also manipulated water availability, a limiting resource due to the sandy soils. At the most severe part of the coastal gradient (i.e. closest to the seashore), both intensity and importance of the interaction between G. opposita and T. brasiliensis were negatively related to stress, with a pattern consistent across distinct life stages of the target species. However, the sign of the net interaction depended on the life stage of the target species. Our results provide empirical evidence that the role of facilitation tends to wane, leading to neutral or even negative net interactions between species as stress reaches its maximum, as predicted by the recent refinements of the SGH.

[Nursing, a quality service? The patient answers]. / Enfermagem, um serviço de qualidade? O paciente responde.

Being quality an updated concept in several productive sectors, we have tried to study this concept in nursing service environment at the patient's point of view. For reaching this goal, a questionnaire has been made upon which 45 Hospital de Clínicas de Porto Alegre interned patients have produced their opinions. It has been shown that generally speaking, the nursing service has been satisfactory although there is some critic from some clients and improvement could be worked out.