Palynomorphs in southern Western Australian lake sediments: evidence of climate change and hypersalinity during the Cenozoic

Palynology ◽  
2020 ◽  
pp. 1-14
Author(s):  
Carlos A. Sanchez Botero ◽  
Francisca E. Oboh-Ikuenobe ◽  
Lutfia Grabel ◽  
Onema C. Adojoh
2015 ◽  
Vol 37 (4) ◽  
pp. 331 ◽  
Author(s):  
Ellena Shaw ◽  
G. Bradd Witt

This research analysed contemporary publications concerning climate change adaptation in the agricultural systems of the Western Australian rangelands. The term ‘systems’ refers to the supportive economic and social systems as well as agricultural industries. The aim of the study was to evaluate how the adaptive capacity of agricultural systems is supported given the anticipated challenges of climatic changes. The conceptual framework of adaptive capacity was employed to evaluate progress towards improving adaptation and resilience. Eight key indicators of adaptive capacity formed the evaluative criteria, and were applied to a wide range of publicly available documents relevant to the Western Australian rangelands. Progress towards building adaptive capacity was also evaluated by classifying the documents as ‘aspirational’, ‘in action’ or ‘assessed’. The institutional support for adaptive capacity was found to be adequate, as there was sufficient evidence that relevant institutions were providing mechanisms for social, economic and environmental adaptation in the face of climate change. The viability of the agricultural systems of the Western Australian rangelands has been in decline for some time and, therefore, the degree to which efforts to improve adaptive capacity have been successful was difficult to assess. There were methodological limitations of this research due to the limited breadth of available data and subjectivity within the data analysis process, which may have inhibited the accuracy of the findings and recommendations. Also difficulties inherent in quantifying social, economic and environmental processes at differing geographic and temporal scales, were apparent. This raises important questions regarding the extent to which the literature is able to appropriately reflect actual adaptation within the rangelands, and the extent to which stakeholders (community, pastoralists and regional organisations) perceive that adequate institutional support is being provided.


Quaternary ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 11 ◽  
Author(s):  
Sien Thys ◽  
Maarten Van Daele ◽  
Nore Praet ◽  
Britta Jensen ◽  
Thomas Van Dyck ◽  
...  

Snow avalanches cause many fatalities every year and damage local economies worldwide. The present-day climate change affects the snowpack and, thus, the properties and frequency of snow avalanches. Reconstructing snow avalanche records can help us understand past variations in avalanche frequency and their relationship to climate change. Previous avalanche records have primarily been reconstructed using dendrochronology. Here, we investigate the potential of lake sediments to record snow avalanches by studying 27 < 30-cm-long sediment cores from Kenai Lake, south-central Alaska. We use X-ray computed tomography (CT) to image post-1964 varves and to identify dropstones. We use two newly identified cryptotephras to update the existing varve chronology. Satellite imagery is used to understand the redistribution of sediments by ice floes over the lake, which helps to explain why some avalanches are not recorded. Finally, we compare the dropstone record with climate data to show that snow avalanche activity is related to high amounts of snowfall in periods of relatively warm or variable temperature conditions. We show, for the first time, a direct link between historical snow avalanches and dropstones preserved in lake sediments. Although the lacustrine varve record does not allow for the development of a complete annual reconstruction of the snow avalanche history in the Kenai Lake valley, our results suggest that it can be used for long-term decadal reconstructions of the snow-avalanche history, ideally in combination with similar records from lakes elsewhere in the region.


2012 ◽  
Vol 60 (2) ◽  
pp. 128 ◽  
Author(s):  
Pippa J. Michael ◽  
Paul B. Yeoh ◽  
John K. Scott

The factors determining the distribution of the Western Australian endemic Solanum hoplopetalum Bitter & Summerh. (Solanaceae) were assessed because it was identified as a potential weed risk to Australian cropping regions, including under climate change scenarios. Incubation at constant temperatures determined daily plant growth rates and plants required 1380 degree-days above a threshold of 12.4°C to complete growth to flowering. From this and published information on the plant’s biology, we developed a mechanistic niche model using CLIMEX. The model projection for current climates produced a highly significant match to known distribution records. Spatially, the lower south-west and areas eastwards to South Australia, western New South Wales and southern parts of the Northern Territory were climatically suitable for growth of S. hoplopetalum. However, by 2070 the area under risk decreases, with the projected distribution under climate change contracting southwards. We hypothesise that climatic extremes and edaphic factors, possibly high soil pH, may be major factors determining the current distribution of S. hoplopetalum. Containment on the southern edge of the current distribution, interstate quarantine and local eradication in new areas of invasion are recommended as management options to combat the potential for this native weed to spread.


2020 ◽  
Vol 709 ◽  
pp. 136115 ◽  
Author(s):  
Clare B. Miller ◽  
Michael B. Parsons ◽  
Heather E. Jamieson ◽  
Omid H. Ardakani ◽  
Braden R.B. Gregory ◽  
...  

2013 ◽  
Vol 79 (2) ◽  
pp. 284-291 ◽  
Author(s):  
Yan Zeng ◽  
Jingan Chen ◽  
Jule Xiao ◽  
Liang Qi

AbstractThe Rb/Sr ratio of lake sediments has been demonstrated to be a potential indicator of chemical weathering by increasing work. However, Rb and Sr in lake sediments are derived from both chemical weathering and physical erosion. Rb and Sr of different forms in lake sediments may record different environmental processes and information. In this study, the variation patterns of Rb and Sr of different forms in sediments of Daihai Lake were investigated. The results show that Rb and Sr of different forms display noticeably different variation patterns due to their different sources and associated environmental processes. Using the Rb/Sr ratios of bulk lake sediments to reflect chemical weathering is not accurate. The non-residual Sr of the sediments without detrital carbonates, representing the Sr leached from the catchment, can be used as an index of chemical weathering because the weathering of Sr minerals is very sensitive to climate change, and the non-residual Sr content of the sediment is determined more by Sr2 + influx than by the physicochemical conditions of lake water. The correspondence between the non-residual Sr and TIC/TOC in Daihai Lake also indicates that the non-residual Sr of the sediments is a good indicator of chemical weathering in the catchment.


1999 ◽  
Vol 18 (3) ◽  
pp. 321-329 ◽  
Author(s):  
Achim Brauer ◽  
Christoph Endres ◽  
Christina Günter ◽  
Thomas Litt ◽  
Martina Stebich ◽  
...  

2013 ◽  
Vol 28 (2) ◽  
pp. 189-199 ◽  
Author(s):  
B. Wilhelm ◽  
F. Arnaud ◽  
P. Sabatier ◽  
O. Magand ◽  
E. Chapron ◽  
...  

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