Primary succession in Mount Pinatubo: Habitat availability and ordination analysis.

Vegetation structure on the east flank of Mount Pinatubo was investigated to determine the inventory of species at 15 y post-eruption, then to ascertain environmental variables that have influenced the early patterns of primary succession. Unconstrained and constrained ordination methods were used to determine the influence of spatial, elevation, and substrate patterns on vegetation. Vegetation was assigned to one of 3 habitat types. Scours were eroded flat surfaces, terraces were perched flat surfaces, and talus piles were created along the canyon edges as mass waste events. The influence of habitat type on vegetation was multifaceted because they represent different conditions and different histories. The talus piles have preferential access to colonists from the vegetation on the canyon walls above and a more benign microclimate than the exposed terrace and scour sites. Scoured sites on the valley floor exhibited the least vegetation cover, as these substrates had the least mature surfaces and the most restricted capacity for root exploration. Perched terraces exhibited greater plant dominance than did the other habitats in the early stages of succession because of the ubiquitous appearance of Parasponia rugosa as initial colonists on these relatively flat surfaces. Polynomial canonical correspondence analysis was more closely aligned with the pattern of vegetation than linear canonical correspondence analysis, and therefore more closely approximated accurate descriptions of correlations among site ordination positions and measured variables. These results confirm that a variety of statistical approaches can clarify applications for restoration ecology following landslide and volcanic disturbances or agriculture and forestry anthropogenic disturbances in the lowland tropics.

Grado de implementación de actividades preventivas por parte de los médicos residentes de Medicina Familiar y Comunitaria en las consultas de Atención Primaria / Implementation of preventive activities by family and community medicine residents in primary care clinics

ObjetivoDeterminar el grado en que los médicos residentes de medicina familiar y comunitaria realizan actividades preventivas durante su estancia en el centro de salud, así como estimar el tiempo empleado en llevarlas a cabo.DiseñoEstudio observacional, descriptivo y transversal.EmplazamientoCentros de salud docentes de los distritos de atención primaria de Córdoba (centro) y Guadalquivir.ParticipantesCuarenta médicos residentes y 384 entrevistas clínicas realizadas con pacientes que acuden a la consulta.Mediciones principalesTres médicos residentes videograban y visualizan las consultas que registran las actividades preventivas efectuadas según las recomendaciones del Programa de Actividades Preventivas y de Promoción de la Salud del año 2005 y el tiempo empleado en cada entrevista en llevar a cabo estas actividades.ResultadosEn el 72,1% de las consultas (IC del 95%: de 67,6 a 76,5) no se realiza ninguna actividad preventiva. Las actividades más frecuentes son las de prevención secundaria (70,1%), destaca en primer lugar la toma de la presión arterial (8,1%). El tiempo medio por consulta en aquéllas en las que no se realizan actividades preventivas es de 5,6min (DE=3,1), mientras que en las que sí se realizan es de 7,04 (DE=3,05) (p<0,0001).ConclusionesLa realización de actividades preventivas por parte de los médicos residentes en las consultas de atención primaria es muy escasa. Una consulta que incluya actividades preventivas requiere de un tiempo significativamente mayor que una que no las incluya(AU)

ObjectiveTo determine the level of preventive activities carried out by Family and Community Medicine medical residents during their stay in the Health Centre, as well as to estimate the time involved in carrying them out.DesignCross-sectional, descriptive, observational study.SettingTeaching Health Centres in the Central- Cordoba and Guadalquivir Primary Care Districts.ParticipantsForty medical residents and 384 clinical interviews with patients who were seen at the clinic.Main measurementsThe consultations were video recorded and looked at by three medical residents who recorded the preventive activities carried out according to the 2005 PAPPS (Health Promotion and Disease Prevention Activities) recommendations, as well as the time employed in performing these activities.ResultsNo preventive activities were performed in 72.1% (95% CI: 67.6 to 76.5%) of the consultations. The most frequent activities were secondary prevention (70.1%), mainly the taking of blood pressure (8.1%). The mean consultation time when there were no preventive activities carried out was 5.6min (SD=3.1), whilst in those that did perform them it was 7.04min (SD=3.05) (P<0.0001).ConclusionsThe performing of preventive activities by medical residents in Primary Care clinics is very limited. A consultation that includes preventive activities requires a significantly longer time than in those that do not include them(AU)

[Implementation of preventive activities by family and community medicine residents in primary care clinics]. / Grado de implementación de actividades preventivas por parte de los médicos residentes de Medicina Familiar y Comunitaria en las consultas de Atención Primaria.

OBJECTIVE: To determine the level of preventive activities carried out by Family and Community Medicine medical residents during their stay in the Health Centre, as well as to estimate the time involved in carrying them out. DESIGN: Cross-sectional, descriptive, observational study. SETTING: Teaching Health Centres in the Central- Cordoba and Guadalquivir Primary Care Districts. PARTICIPANTS: Forty medical residents and 384 clinical interviews with patients who were seen at the clinic. MAIN MEASUREMENTS: The consultations were video recorded and looked at by three medical residents who recorded the preventive activities carried out according to the 2005 PAPPS (Health Promotion and Disease Prevention Activities) recommendations, as well as the time employed in performing these activities. RESULTS: No preventive activities were performed in 72.1% (95% CI: 67.6 to 76.5%) of the consultations. The most frequent activities were secondary prevention (70.1%), mainly the taking of blood pressure (8.1%). The mean consultation time when there were no preventive activities carried out was 5.6 min (SD=3.1), whilst in those that did perform them it was 7.04 min (SD=3.05) (P<0.0001). CONCLUSIONS: The performing of preventive activities by medical residents in Primary Care clinics is very limited. A consultation that includes preventive activities requires a significantly longer time than in those that do not include them.

Impact of curve construction and community dynamics on the species-time relationship.

The species-time relationship (STR) describes how the species richness of a community increases with the time span over which the community is observed. This temporal scaling provides insight into theoretical questions on species diversity patterns as well as applied questions on the appropriate time scale for biodiversity assessments. To better understand STRs, we discuss the methods used to construct STRs in the literature and derive the impact of curve construction on STR properties. Using vegetation data from Mount St. Helens, Washington, USA, we illustrate the sensitivity of the STR to construction under colonization-dominated dynamics. This study highlights the importance of considering the type of STR when interpreting, comparing, and applying STRs, particularly in disturbed or successional systems.

Vegetation patterns 25 years after the eruption of Mount St. Helens, Washington, USA.

In 2004, we surveyed the vegetation on Mount St. Helens to document changes since 1992. We asked how communities differentiate and if they develop predictable relationships with local environments. We sought evidence from links between species and environment and changes in community structure in 271 250-m(2) plots. The habitats of the seven community types (CTs) overlapped broadly. Ordination methods demonstrated weak correlations among species distributions and location, elevation, and surface variables. Comparisons to 1992 by habitat demonstrated a large increase in plant cover and substantial development of vegetation structure. Pioneer species declined while mosses increased proportionately leading to more pronounced dominance hierarchies in most habitats. In Lupinus colonies, dominance declined, and diversity increased due to the increased abundance of formerly rare species. On once barren sites, dominance increased, but diversity changed slightly, which suggested the incipient development of competitive hierarchies. Weak correlations between vegetation and the environment suggested that initially stochastic establishment patterns had not yet been erased by deterministic factors. A vegetation mosaic that is loosely controlled by environmental factors may produce different successional trajectories that lead to alternative stable communities in similar habitats. This result has implications for restoration planning.

Colonization of volcanic deserts from productive patches.

Dense vegetation can augment landscape biodiversity, promote recovery of surrounding ecosystems, and facilitate colonization. However, dispersal limits affect vegetation structure early in succession to a degree that is not widely appreciated. We studied two contrasting densely vegetated habitats located on Mount St. Helens to explore their effects on surrounding vegetation. We sampled refugia and adjacent barrens and compared them to a study conducted 5 yr earlier. We sampled isolated wetlands and their surroundings. Species richness, total cover, cover of most dispersal types, the information statistic (H'), and the complement of Simpson's Index (D) were negatively correlated with distance from the refugia up to 32 m. Compared to 1997, the 2002 transects had higher cover, and adjacent samples were more similar to one another. Dominance had shifted from wind-dispersed species to more persistent species with less effective dispersal mechanisms. The pattern of these results demonstrated that refugia were a major, but indirect source of recruitment for many species. The influence of wetlands on surrounding vegetation recovery was even more spatially localized. This study demonstrates that dispersal from surviving and rapidly recovered vegetation has been overemphasized as a mechanism for vegetation recovery. The effects of dense vegetation did not extend beyond 32 m in our studies, and local effects appear to diminish over time.

On the variability of chlorogenic acid concentration.

The plasticity of phenolic acid concentration in plants under various physiological stress situations raises questions concerning the ecological significance of such behavior. Helianthus annuus L. is remarkably plastic with regard to chlorogenic and ischlorogenic acid concentrations when subjected to nitrogen deficiency, NaCl-stress, short exposures to UV radiation or to combinations of these stresses. Stress due to NaCl has not previously been reported to produce this effect.I propose that chlorogenic acid is representative of a group of chemicals which have originated as regulators of various metabolic systems under stress and have subsequently acquired allelochemic properties against pathogens, herbivores, and competitors. If this hypothesis is correct then specific patterns of distribution with regard to concentrations of phenolic acids should be found. Some such predictions are discussed and means of distinguishing between various selective agents are explored. Generally, if natural environmental stress stimulates phenolic acid concentrations and hence more efficient growth patterns, then for several kinds of variables, higher concentrations should be found in more rather than less stressful habitats. If biological agents are significant agents of natural selection for this group of substances, such a pattern should not occur in some cases.