title: Extreme high lichen growth rates detected in recently deglaciated areas in Tierra del Fuego

authors: Sancho, Leopoldo G.

subjects: Tierra del Fuego

abstract: The goals of this study were to accurately determine the annual growth rate of two key lichen species for lichenometric studies in Tierra del Fuego and to provide more information on recent glacial evolution in the southernmost mountain range of South America. The study site was located on recent moraines deposited in front of a terminus of Pia Glacier in the East Arm of Pia Bay, a fjord of the Beagle Channel. Lichenometric measurements were made of the maximum and minimum axes on the five largest thalli of Rhizocarpon geographicum and Placopsis perrugosa at selected localities in the recently deglaciated area. Average growth rates were estimated from dated surfaces to be 0.63 mm year⁻¹ for R. geographicum and of 9.0 mm year⁻¹ for P. perrugosa. However, maximum growth rate of individual thalli of P. perrugosa could be as high as about 20 mm year⁻¹ increase in diameter directly measured from comparison between pictures taken over a 2-year interval. Both species had an almost linear increase in diameter size with the age of the rock surfaces and the distance from the glacier. The rapid colonization and growth of the lichens is mirrored by the higher plants with ecesis for Nothofagus trees being estimated at 4 years and height growth elongation at 30 cm year⁻¹.

text: Extreme high lichen growth rates detected in recently deglaciated areas in Tierra del Fuego The goals of this study were to accurately determine the annual growth rate of two key lichen species for lichenometric studies in Tierra del Fuego and to provide more information on recent glacial evolution in the southernmost mountain range of South America. The study site was located on recent moraines deposited in front of a terminus of Pia Glacier in the East Arm of Pia Bay, a fjord of the Beagle Channel. Lichenometric measurements were made of the maximum and minimum axes on the five largest thalli of Rhizocarpon geographicum and Placopsis perrugosa at selected localities in the recently deglaciated area. Average growth rates were estimated from dated surfaces to be 0.63 mm year⁻¹ for R. geographicum and of 9.0 mm year⁻¹ for P. perrugosa. However, maximum growth rate of individual thalli of P. perrugosa could be as high as about 20 mm year⁻¹ increase in diameter directly measured from comparison between pictures taken over a 2-year interval. Both species had an almost linear increase in diameter size with the age of the rock surfaces and the distance from the glacier. The rapid colonization and growth of the lichens is mirrored by the higher plants with ecesis for Nothofagus trees being estimated at 4 years and height growth elongation at 30 cm year⁻¹.

year: 2010

title: Geochemically defined space-for-time transects successfully capture microbial dynamics along lacustrine chronosequences in a polar desert

authors: Monteiro, Maria R.

subjects: Science & Technology

abstract: The space-for-time substitution approach provides a valuable empirical assessment to infer temporal effects of disturbance from spatial gradients. Applied to predict the response of different ecosystems under current climate change scenarios, it remains poorly tested in microbial ecology studies, partly due to the trophic complexity of the ecosystems typically studied. The McMurdo Dry Valleys (MDV) of Antarctica represent a trophically simple polar desert projected to experience drastic changes in water availability under current climate change scenarios. We used this ideal model system to develop and validate a microbial space-for-time sampling approach, using the variation of geochemical profiles that follow alterations in water availability and reflect past changes in the system. Our framework measured soil electrical conductivity, pH, and water activity in situ to geochemically define 17 space-for-time transects from the shores of four dynamic and two static Dry Valley lakes. We identified microbial taxa that are consistently responsive to changes in wetness in the soils and reliably associated with long-term dry or wet edaphic conditions. Comparisons between transects defined at static (open-basin) and dynamic (closed-basin) lakes highlighted the capacity for geochemically defined space-for-time gradients to identify lasting deterministic impacts of historical changes in water presence on the structure and diversity of extant microbial communities. We highlight the potential for geochemically defined space-for-time transects to resolve legacy impacts of environmental change when used in conjunction with static and dynamic scenarios, and to inform future environmental scenarios through changes in the microbial community structure, composition, and diversity.

text: Geochemically defined space-for-time transects successfully capture microbial dynamics along lacustrine chronosequences in a polar desert The space-for-time substitution approach provides a valuable empirical assessment to infer temporal effects of disturbance from spatial gradients. Applied to predict the response of different ecosystems under current climate change scenarios, it remains poorly tested in microbial ecology studies, partly due to the trophic complexity of the ecosystems typically studied. The McMurdo Dry Valleys (MDV) of Antarctica represent a trophically simple polar desert projected to experience drastic changes in water availability under current climate change scenarios. We used this ideal model system to develop and validate a microbial space-for-time sampling approach, using the variation of geochemical profiles that follow alterations in water availability and reflect past changes in the system. Our framework measured soil electrical conductivity, pH, and water activity in situ to geochemically define 17 space-for-time transects from the shores of four dynamic and two static Dry Valley lakes. We identified microbial taxa that are consistently responsive to changes in wetness in the soils and reliably associated with long-term dry or wet edaphic conditions. Comparisons between transects defined at static (open-basin) and dynamic (closed-basin) lakes highlighted the capacity for geochemically defined space-for-time gradients to identify lasting deterministic impacts of historical changes in water presence on the structure and diversity of extant microbial communities. We highlight the potential for geochemically defined space-for-time transects to resolve legacy impacts of environmental change when used in conjunction with static and dynamic scenarios, and to inform future environmental scenarios through changes in the microbial community structure, composition, and diversity.

year: 2022

title: Violation of te whare tangata - the maternal body: Young women's journeys through pregnancy and partner terrorism

authors: Marsh, Tuihana M.

subjects: Partner Terrorism

abstract: Partner terrorism is a leading social issue in Aotearoa. It occurs with such frequency and ferocity that it is often considered an epidemic. This has placed us in the shameful position of being the highest ranked nation in the western world for the prevalence of intimate partner violence. This research explored young women’s experiences of intimate partner violence during pregnancy. Eleven women aged 14 - 17 years when pregnant were interviewed. A mana wāhine theoretical perspective was employed, guided by a kaupapa Māori research methodology. Pūrākau was used as a method to present and validate the women’s voices.
The key findings identified that these relationships began with the potential of any other relationship. However, they typically followed a pattern of co-habituation and entrapment through pregnancy and financial dependence. It was evident the partner terrorism was brought into these relationships by the terrorist partners, and was the first experience of this violence for many of the women. The terrorism continued to escalate. Separating from their terrorist partners did not result in the women being any safer, with some continuing to experience life-threatening acts of terrorism post separation. Pregnancy did not serve as a protective factor: the violation of te whare tangata generally occurred before, during and after pregnancy. Often, the acts of terrorism escalated following the birth of their pēpī, with their partner’s terrorism being a direct assault on ūkaipō, disrupting bonding and mothering practices. Many of the women were able to recognise the terrorism to which they were subjected only in hindsight. Despite this, they showed ingenuity and resilience in the ways they resisted the terrorism in efforts to keep themselves and their pēpī safe. Breaking free of these relationships demanded intervention and support from outsiders. The women remain strongly committed to the welfare of their pēpī.

text: Violation of te whare tangata - the maternal body: Young women's journeys through pregnancy and partner terrorism Partner terrorism is a leading social issue in Aotearoa. It occurs with such frequency and ferocity that it is often considered an epidemic. This has placed us in the shameful position of being the highest ranked nation in the western world for the prevalence of intimate partner violence. This research explored young women’s experiences of intimate partner violence during pregnancy. Eleven women aged 14 - 17 years when pregnant were interviewed. A mana wāhine theoretical perspective was employed, guided by a kaupapa Māori research methodology. Pūrākau was used as a method to present and validate the women’s voices.
The key findings identified that these relationships began with the potential of any other relationship. However, they typically followed a pattern of co-habituation and entrapment through pregnancy and financial dependence. It was evident the partner terrorism was brought into these relationships by the terrorist partners, and was the first experience of this violence for many of the women. The terrorism continued to escalate. Separating from their terrorist partners did not result in the women being any safer, with some continuing to experience life-threatening acts of terrorism post separation. Pregnancy did not serve as a protective factor: the violation of te whare tangata generally occurred before, during and after pregnancy. Often, the acts of terrorism escalated following the birth of their pēpī, with their partner’s terrorism being a direct assault on ūkaipō, disrupting bonding and mothering practices. Many of the women were able to recognise the terrorism to which they were subjected only in hindsight. Despite this, they showed ingenuity and resilience in the ways they resisted the terrorism in efforts to keep themselves and their pēpī safe. Breaking free of these relationships demanded intervention and support from outsiders. The women remain strongly committed to the welfare of their pēpī.

year: 2019