Variability in water use by phreatophytic Banksia woodland vegetation of the Swan Coastal Plain, Western Australia

Seasonal changes exist in source-water utilisation by Banksia woodland species overlying a shallow aquifer on the Swan Coastal Plain in Western Australia These were studied to identify the importance of groundwater as a water source to this vegetation. Intra-and interspecific variation in seasonal water use was investigated across the dominant overstorey and understorey species, with particular emphasis on species of different rooting morphologies. Seasonal water use was investigated across a topographical gradient ranging from a groundwater depth of 2.5 to 30 metres, a scenario representative of the coastal sand-dune system. An examination was also made of the response of woodland vegetation to an induced and rapid temporal separation from the groundwater able, beyond the normal range of groundwater fluctuation. To investigate a species\u27 seasonal water usage, measurements of the naturally occurring stable isotope of hydrogen in water (deuterium, δ2H) were used to distinguish among potential plant water sources. Isotopic ratios from vascular water of the study species were compared with those of potential sources of precipitation, soil moisture and groundwater. The primary assumptions of this method were validated for the study species in laboratory experiments, and field-sampling strategies were developed. Through this process, the water sources available to plants were identified. Mixing models were employed to calculate the proportion of groundwater used. The results of this study confirm that groundwater is an important water source to both overstorey and understorey components of the woodland. Phreatophytic species were characterised by a deep root system, in which the tap root played a significant role in groundwater uptake. These species derived some of their water from groundwater throughout the dry-wet cycle. With the onset of the hot, Mediterranean summer, they increased their use of deep moisture sources, including groundwater. Variability in groundwater usage was observed at the interspecific and intraspecific level. This was dependent on root-system distribution and maximum root depth. For those species capable of using groundwater, the degree to which it was utilised was dependent on the proximity of groundwater (i.e. the depth to the water table), and the availability of moisture in shallower horizons of the soil profile (i.e. the season). For individuals occurring at shallow depth to water (\u3c 8 m), groundwater was an important water source: whereas, at greater depths (≥8 m) its importance decreased as it was used in lower proportions and/or for shorter durations. Comparisons of within-species variation revealed disparities in groundwater usage, and possibly dependency, between the dominant overstorey Banksia species. Banksia ilicifolio, a species confined to habitats where groundwater depth is ≤8 m, was dependent on groundwater during the dry summer period (up to 90% of water used was groundwater) and may be considered a summer obligate phreatophyte. B. attenuata is a summer facultative phreatophyte, occurring where groundwater depth is 2 to \u3e30m with groundwater accounting for between 5 to 75% of water used depending on depth to the water table. These results suggest the possibility of an obligate-facultative phreatophyte distinction. The response of phreatophytic Banksia species to changes in the groundwater regime beyond the normal range of groundwater fluctuation confirmed the seasonal nature of groundwater dependence, and varied sensitivity of individuals according to their position within the sandplain landscape (i.e. proximity to groundwater)

Miomatosis uterina

Los miomas uterinos son tumores primariamente benignos que se originan en el músculo liso. Tienen un comportamiento clínico variable, desde no ser percibidos por su carácter asintomático hasta situaciones límites en la que comprometen la calidad de vida. La práctica del examen ginecológico periódico proporciona hallazgos y permite el accionar de terapéuticas acordes a cada caso. Con prevalencia en la madurez sexual, suelen detectarse en pacientes adolescentes, en las que debe controlarse su evolución. La incorporación de tecnologías quirúrgicas endoscópicas y los fármacos actuales combinan una terapéutica cada vez más aceptada, logrando la preservación uterina como también permiten una perspectiva diferente en pacientes jóvenes. No puede omitirse la importancia de la miomatosis uterina sobre la reproducción humana y su evolución, como también en distintas situaciones de salud/enfermedad en las que muestra su importancia como patología prevalente.Facultad de Ciencias Médica

Projected risks to groundwater-dependent terrestrial vegetation caused by changing climate and groundwater abstraction in the Central Perth Basin, Western Australia

The effect of potential climate change on groundwater-dependent vegetation largely depends on the nature of the climate change (drying or wetting) and the level of current ecosystem dependence on groundwater resources. In south-western Australia, climate projections suggest a high likelihood of a warmer and drier climate. The paper examines the potential environmental impacts by 2030 at the regional scale on groundwater-dependent terrestrial vegetation (GDTV) adapted to various watertable depths, on the basis of the combined consideration of groundwater modelling results and the framework for GDTV risk assessment. The methodology was tested for the historical period from 1984 to 2007, allowing validation of the groundwater model results\u27 applicability to such an assessment. Climate change effects on GDTV were evaluated using nine global climate models under three greenhouse gas emission scenarios by applying the climate projections to groundwater models. It was estimated that under dry climate scenarios, GDTV is likely to be under high and severe risk over more than 20% of its current habitat area. The risk is also likely to be higher under an increase in groundwater abstraction above current volumes. The significance of climate change risk varied across the region, depending on both the intensity of the change in water regime and the sensitivity of the GDTV to such change. Greater effects were projected for terrestrial vegetation dependent on deeper groundwater (6-10m)

Water relations of evergreen and drought-deciduous trees along a seasonally dry tropical forest chronosequence

Seasonally dry tropical forests (SDTF) are characterized by pronounced seasonality in rainfall, and as a result trees in these forests must endure seasonal variation in soil water availability. Furthermore, SDTF on the northern Yucatan Peninsula, Mexico, have a legacy of disturbances, thereby creating a patchy mosaic of different seral stages undergoing secondary succession. We examined the water status of six canopy tree species, representing contrasting leaf phenology (evergreen vs. drought-deciduous) at three seral stages along a fire chronosequence in order to better understand strategies that trees use to overcome seasonal water limitations. The early-seral forest was characterized by high soil water evaporation and low soil moisture, and consequently early-seral trees exhibited lower midday bulk leaf water potentials (ΨL) relative to late-seral trees (−1.01 ± 0.14 and −0.54 ± 0.07 MPa, respectively). Although ΨL did not differ between evergreen and drought-deciduous trees, results from stable isotope analyses indicated different strategies to overcome seasonal water limitations. Differences were especially pronounced in the early-seral stage where evergreen trees had significantly lower xylem water δ18O values relative to drought-deciduous trees (−2.6 ± 0.5 and 0.3 ± 0.6‰, respectively), indicating evergreen species used deeper sources of water. In contrast, drought-deciduous trees showed greater enrichment of foliar 18O (∆18Ol) and 13C, suggesting lower stomatal conductance and greater water-use efficiency. Thus, the rapid development of deep roots appears to be an important strategy enabling evergreen species to overcome seasonal water limitation, whereas, in addition to losing a portion of their leaves, drought-deciduous trees minimize water loss from remaining leaves during the dry season

Floodplain ecohydrology : climatic, anthropogenic, and local physical controls on partitioning of water sources to riparian trees

This research was financially supported by Observatoire Hommes/Milieux Vallee du Rhone, The Royal Society (RG100590), The Carnegie Trust for the Universities of Scotland, and the Rhone-Alpes region via the ARC Environment program 2013. We also acknowledge NERC PhD studentship support to Sargeant and Evans.Seasonal and annual partitioning of water within river floodplains has important implications for ecohydrologic links between the water cycle and tree growth. Climatic and hydrologic shifts alter water distribution between floodplain storage reservoirs (e.g., vadose, phreatic), affecting water availability to tree roots. Water partitioning is also dependent on the physical conditions that control tree rooting depth (e.g., gravel layers that impede root growth), the sources of contributing water, the rate of water drainage, and water residence times within particular storage reservoirs. We employ instrumental climate records alongside oxygen isotopes within tree rings and regional source waters, as well as topographic data and soil depth measurements, to infer the water sources used over several decades by two co-occurring tree species within a riparian floodplain along the Rhône River in France. We find that water partitioning to riparian trees is influenced by annual (wet versus dry years) and seasonal (spring snowmelt versus spring rainfall) fluctuations in climate. This influence depends strongly on local (tree level) conditions including floodplain surface elevation and subsurface gravel layer elevation. The latter represents the upper limit of the phreatic zone and therefore controls access to shallow groundwater. The difference between them, the thickness of the vadose zone, controls total soil moisture retention capacity. These factors thus modulate the climatic influence on tree ring isotopes. Additionally, we identified growth signatures and tree ring isotope changes associated with recent restoration of minimum streamflows in the Rhône, which made new phreatic water sources available to some trees in otherwise dry years.Publisher PDFPeer reviewe