Causes and consequences of variation in snow incidence on the high mountains of Tasmania, 1983–2013

2017 ◽  
Vol 65 (3) ◽  
pp. 214 ◽  
Author(s):  
Jamie B. Kirkpatrick ◽  
Manuel Nunez ◽  
Kerry L. Bridle ◽  
Jared Parry ◽  
Neil Gibson
Keyword(s):  
Plant Species ◽  
Aerial Photographs ◽  
Climate Indices ◽  
Small Subset ◽  
Climatic Data ◽  
Shrub Cover ◽  
Bare Ground ◽  
Landsat Images ◽  
Decadal Scale ◽  
Warming World

Alpine plant species are considered to have a precarious near future in a warming world, especially where endemic on mountains without a nival zone. We investigated how and why snow patch vegetation and snow incidence varied over recent decades in Tasmania, Australia. Landsat images between 1983 and 2013 were used to calculate the proportion of clear days with snow visible on Mt Field. We compared average annual snow incidence on 74 Tasmanian alpine mountains for 1983–1996 with that for 1997–2013 using the small subset of Landsat runs in which most of Tasmania was clear of cloud. We related the temporal data from Mt Field to Tasmanian climatic data and climate indices to determine the predictors of change. We recorded plant species and life form cover from quadrats in transects through a snow patch on Mt Field in 1983, 2001 and 2014, and mapped decadal scale changes in boundaries and shrub cover at five other snow patches across the extent of the Tasmanian alpine areas from aerial photographs. The incidence of snow fluctuated between 1983 and 2013 at Mt Field with no overall trend. Snow incidence was less on lower elevation alpine mountains in the period 1997–2013 than in the period 1983–1996, but showed a weak opposite trend on mountains higher than 1350 m. The contrast in trends may be a consequence of the effect on lapse rates of stronger frontal winds associated with a steepening of latitudinal pressure gradients. At Mt Field, bare ground decreased, cover of cushion plants and tall shrubs increased and obligate snow patch species were persistent. The trends we observed in both vegetation and snow incidence differ markedly from those observed on mainland Australia. The increase in shrub cover and decrease in bare ground on Mt Field were unexpected, given the constancy in incidence of snow. These results may relate to ongoing recovery from a fire in the 1960s, as the shrub species that have increased are fire-sensitive, obligate seeders and there has been no indication of warming since 1983 in the climatic record for western Tasmania. There is a possibility that some Tasmanian alpine areas might act as long-term refugia from general warming.

Contemporary challenges for Shoreline Change Analysis

2020 ◽  
Author(s):  
Sue Brooks ◽  
Jamie Pollard ◽  
Tom Spencer
Keyword(s):  
Water Level ◽  
Methodological Approach ◽  
Shoreline Change ◽  
Data Availability ◽  
Aerial Photographs ◽  
Publication Date ◽  
Landsat Images ◽  
Change Analysis ◽  
Decadal Scale ◽  
Shoreline Change Analysis

<p>Shoreline change analysis has been deployed across a range of spatio-temporal scales. Accordingly, shoreline change studies have sought to capture shoreline dynamics at a variety of scales, ranging from the local impacts of individual storms to global trends measured over multiple decades. The scale at which we can approach the issue of shoreline change is, to a large extent, determined by the availability of data over time and space. With existing threats from the interactions between accelerated sea level rise, changing storminess and human intervention, shoreline change analysis has never been more relevant or challenging. Historic, centennial-scale shoreline change analysis relies on historic maps where there is normally just a single proxy indicator for consistent shoreline position; the mean water level of ordinary tides on UK Ordnance Survey maps, for example. Occasionally where there are specific coastal landforms that can be mapped, there might be a second proxy such as cliff top position. Shoreline change rates can be determined by extracting these proxies from sequential map surveys, provided the survey dates (ie: not the map publication date) are known.</p><p> </p><p>Shoreline change quantification for more recent decadal-scale periods has been greatly enhanced by increased data availability. This is exemplified by analyses that use widespread coverage available from aerial photographs (past 3 decades). Even more recently on near-annual scales Light Detection and Ranging (LiDAR) data are becoming the norm for capturing storm impacts and shoreline change, enabling volumetric assessments of change in addition to the more traditional linear approaches. LiDAR is enhanced by ground survey Real Time Kinematic (RTK) Instrumentation that can be timed to coincide with storms. As the frequency of dataset capture has increased so has the spatial scale of coverage. Hence the latest shoreline change assessments are global in scale and use Landsat images to focus on hotspots of shoreline change (advance as well as retreat) over the past 30 years. Considering all scales together raises three central questions for shoreline change analysis and these are addressed in this paper.</p><p> </p><p>Firstly, what methodological approach is most suitable for delimiting shorelines and generating the underpinning digitised shorelines for shoreline change assessment?</p><p>Secondly, what lessons can be learnt from using an approach that combines both proxy-based (visually discernible signatures) and datum-based (related to a particular water level) shorelines that change differentially with respect to different process-drivers?</p><p>Thirdly, given the current state-of-the-art around data availability, what is the most appropriate scale to approach shoreline change assessments?</p>

Dynamics of Perennial Plants in the Mulga (Acacia aneura F. Muell) Zone of Western Australia. I. Rates of Population Change.

1986 ◽  
Vol 8 (1) ◽  
pp. 18 ◽  
Author(s):  
HG Gardiner
Keyword(s):  
Environmental Factors ◽  
Plant Species ◽  
Western Australia ◽  
Population Change ◽  
Aerial Photographs ◽  
Normal Period ◽  
Macropus Rufus ◽  
Arid Rangelands ◽  
Acacia Aneura ◽  
Dynamics Of Populations

The dynamics of populations of six plant species and their responses to environmental factors were examined at Yeelirrie station in the Mulga Zone rangelands of Western Australia. Populations of plants were sampled using sequential maps drawn from low level aerial photographs of areas from which livestock had been removed and which were fenced either to exclude or permit grazing by kangaroos (Macropus rufus Desmarest and Macropus robustus Gould). All six plant species were favoured by the combination of wet years (1973-76) and the removal of livestock from these arid rangelands. Increases ranged from about 20 plants/ha/yr (Eremophila leucophylla, Benth.) to more than 700 plants/ha/yr (Eremophila spectabilis, C.A. Gardn.) during this period. Drought (1977-1979) resulted in significant declines that ranged from about 10 plants/ha/yr (Eremophila leucophylla) to nearly 600 plants/ha/yr (Eremophila spectabilis) while three species (Eremophila leucophylla, Maireana glomerifolia, (F. Muell. et Tate) P.G. Wilson and Ptilotus obovatus, Gaud.) either did not change or increased by only 30 to 60 plants/ha/yr during this period. Responses to kangaroo grazing were strongest during 'normal', post-drought years (1980-82) when Eragrostis xerophila, Domin. decreased by 178 plants/ha/yr on grazed areas while on protected areas there was an increase of 299 plants/ha/yr. This response was due to effects on both recruitment and, as discussed by Gardiner (1986), survival. Maireana glomerifolia, another important plant for livestock was suppressed by kangaroo grazing via reduced recruitment during the 'normal' period. Other species (Frankenia paucifora, DC. and Eremophila spectabilis) responded positively to kangaroo grazing activity during the same period.

Remote Sensing of Chinese Tamarisk (Tamarix chinensis) and Associated Vegetation

Weed Science ◽  
1990 ◽  
Vol 38 (3) ◽  
pp. 273-278 ◽  
Author(s):  
J. H. Everitt ◽  
C. J. Deloach
Keyword(s):  
Plant Species ◽  
Aerial Photographs ◽  
Winter Period ◽  
Herbaceous Plant ◽  
Tamarix Chinensis ◽  
Color Film ◽  
Light Reflectance ◽  
Yellow Orange ◽  
Computer Analyses ◽  
Orange Color

Chinese tamarisk is an invader of riparian sites in the southwestern United States and northern Mexico. Plant canopy light reflectance measurements showed that Chinese tamarisk had higher visible (0.55- and 0.65-μm wavelengths and 0.63- to 0.69-μm waveband) reflectance than did associated woody and herbaceous plant species in the late fall-early winter period when its foliage turned a yellow-orange to orange-brown color prior to leaf drop. Chinese tamarisk had a yellow-orange color on conventional color (0.40- to 0.70-μm) aerial photographs during this phenological stage that made it distinguishable from other plant species. Computer analyses of conventional color film positive transparencies showed that Chinese tamarisk populations could be quantified from associated vegetation. This technique can permit area estimates of Chinese tamarisk infestations on wildland areas.

Effects of wildlife grazing on the production, ground cover and plant species composition of an established perennial pasture in the Midlands region, Tasmania

2012 ◽  
Vol 39 (2) ◽  
pp. 123 ◽  
Author(s):  
Rowan W. Smith ◽  
Mick Statham ◽  
Tony W. Norton ◽  
Richard P. Rawnsley ◽  
Helen L. Statham ◽  
...  
Keyword(s):  
Species Composition ◽  
Plant Species ◽  
Ground Cover ◽  
Faecal Pellet ◽  
Individual Plant ◽  
Bare Ground ◽  
Pasture Production ◽  
Wildlife Control ◽  
Biomass Loss ◽  
The Impact

Context Management of grazing wildlife on private land in Tasmania is a contentious issue for landowners, animal-welfare groups and the Tasmanian Government. Wildlife species known to graze pasture include Tasmanian pademelon (Thylogale billardierii), Bennett’s wallaby (Macropus rufogriseus rufogriseus), forester kangaroo (Macropus giganteus), brushtail possum (Trichosurus vulpecula) and fallow deer (Dama dama). Understanding the spatio-temporal patterns of wildlife grazing is important when considering wildlife-control options to mitigate pasture loss; however, limited research has been undertaken. Aims To quantify the impact of wildlife grazing on pasture production and to assess the spatial and temporal pasture biomass loss from an established pasture; to investigate the effect of protecting pastures from wildlife grazing on species composition of an existing perennial pasture; to determine whether wildlife grazing contributes to a decline in the composition of improved pasture species over time and an increase in-ground cover of less desirable grasses and broadleaf weeds; and to examine whether protecting pastures from wildlife grazing could increase ground cover. Methods Pasture biomass loss to wildlife grazing was determined by a paired exclusion-cage method over a 26-month period from February 2008 to April 2010. A quantitative pasture model was used to simulate pasture growth at the study site. Changes in the botanical composition of the sward in response to wildlife grazing were determined by hand-separation, drying and weighing of harvested material, and also by visual estimation of the ground cover of individual plant species. A wildlife faecal-pellet survey was used to develop an index of wildlife feeding activity. Key results Pasture loss to wildlife grazing varied spatially and temporally. Pasture loss decreased with increasing distance from the edge of cover vegetation. The proportion of pasture lost increased during periods of slow pasture growth. Visual estimates of ground cover showed that grazing by wildlife resulted in an increase in bare ground in unprotected swards, whereas protection from grazing resulted in an increase in production of perennial and annual species, as determined by hand-separation of harvested material, and a decrease in bare ground as determined by visual estimate. Faecal-pellet surveys were found to be strongly correlated with pasture biomass losses. Conclusions The proportion of pasture loss to wildlife grazing was found to be influenced by distance from native vegetation and also by pasture availability, which was seasonal. Wildlife can alter the composition of pastures by reducing the ground cover and yield of improved grasses. Continual grazing of pastures by wildlife in addition to rotational sheep grazing may increase the amount of bare ground. Implications Wildlife-control methods need to be carefully chosen if the intended benefits of alleviating pasture biomass losses are to be achieved. Quantifying the loss of pasture is important because it enables the extent and significance of losses to be determined and may inform decisions about the most appropriate wildlife control measures to adopt. Controlling wildlife during periods of slow pasture growth may be important in preventing damage and yield loss of plant species actively growing during these times. Failure to control wildlife may result in a decrease in the composition of desirable plant species.

Wintertime Extreme Precipitation Events along the Pacific Northwest Coast: Climatology and Synoptic Evolution

2012 ◽  
Vol 140 (7) ◽  
pp. 2021-2043 ◽  
Author(s):  
Michael D. Warner ◽  
Clifford F. Mass ◽  
Eric P. Salathé
Keyword(s):  
Pacific Northwest ◽  
Extreme Precipitation ◽  
Precipitable Water ◽  
Small Subset ◽  
Climatic Data ◽  
Central Pacific ◽  
Extreme Precipitation Events ◽  
The Pacific ◽  
Upper Level ◽  
Precipitation Events

Abstract Extreme precipitation events impact the Pacific Northwest during winter months, causing flooding, landslides, extensive property damage, and loss of life. Outstanding questions about such events include whether there are a range of associated synoptic evolutions, whether such evolutions vary along the coast, and the associated rainfall duration and variability. To answer these questions, this study uses 60 years of National Climatic Data Center (NCDC) daily precipitation observations to identify the top 50 events in two-day precipitation at six coastal stations from northern California to northwest Washington. NCEP–NCAR reanalysis data were used to construct synoptic composite evolutions of these events for each coastal location. Most regional flooding events are associated with precipitation periods of 24 h or less, and two-day precipitation totals identify nearly all major events. Precipitation areas of major events are generally narrow, roughly 200 km in width, and most are associated with atmospheric rivers. Composite evolutions indicate negative anomalies in sea level pressure and upper-level height in the central Pacific, high pressure anomalies over the southwest United States, large positive 850-hPa temperature anomalies along the coast and offshore, and enhanced precipitable water and integrated water vapor fluxes over southwest to northeast swaths. A small subset of extreme precipitation events over the southern portion of the domain is associated with a very different synoptic evolution: a sharp trough in northwesterly flow and post-cold-frontal convection. High precipitable water values are more frequent during the summer, but are not associated with heavy precipitation due to upper-level ridging over the eastern Pacific and weak onshore flow that limit upward vertical velocities.

scholarly journals The influence of plant species richness on stress recovery of humans

Web Ecology ◽  
2018 ◽  
Vol 18 (2) ◽  
pp. 121-128 ◽  
Author(s):  
Petra Lindemann-Matthies ◽  
Diethart Matthies
Keyword(s):  
Blood Pressure ◽  
Species Richness ◽  
Plant Species ◽  
Landscape Management ◽  
Plant Species Richness ◽  
Stress Recovery ◽  
Intermediate Species ◽  
Bare Ground ◽  
Relaxation Period ◽  
Post Stress

Abstract. Natural sceneries or single plants may have positive influences on human health. Here we show that plant species richness can positively influence recovery from stress. Meadow-like arrays of different species richness (1, 16, 32, 64 species) were presented to visitors (n=171) of a popular park in Zurich, Switzerland (one array per participant). Participants' systolic blood pressure was measured twice: directly after they had been stressed and once again after a 2 min post-stress relaxation period during which they looked at one of either the meadow-like arrangements of plants in pots or at bare ground, shielded on three sides by a tent-like structure. The decrease in blood pressure was larger when respondents could view an arrangement of plants instead of ground without vegetation. Relaxation was strongest at intermediate species richness (32 species). Age, gender, and a person's attachment to nature did not influence relaxation. Our results indicate that species-rich vegetation may contribute to recovery from stress which should be considered in landscape management and planning.

scholarly journals Impact of transposable elements on methylation and gene expression across natural accessions of Brachypodium distachyon

2020 ◽  
Author(s):  
Michele Wyler ◽  
Christoph Stritt ◽  
Jean-Claude Walser ◽  
Célia Baroux ◽  
Anne C. Roulin
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Transposable Elements ◽  
Plant Species ◽  
Brachypodium Distachyon ◽  
Expression Patterns ◽  
Small Subset ◽  
Molecular Evidence ◽  
Specific Gene ◽  
Plant Genomes

AbstractTransposable elements (TEs) constitute a large fraction of plant genomes and are mostly present in a transcriptionally silent state through repressive epigenetic modifications such as DNA methylation. TE silencing is believed to influence the regulation of adjacent genes, possibly as DNA methylation spreads away from the TE. Whether this is a general principle or a context-dependent phenomenon is still under debate, pressing for studying the relationship between TEs, DNA methylation and nearby gene expression in additional plant species. Here we used the grass Brachypodium distachyon as a model and produced DNA methylation and transcriptome profiles for eleven natural accessions. In contrast to what is observed in Arabidopsis thaliana, we found that TEs have a limited impact on methylation spreading and that only few TE families are associated to a low expression of their adjacent genes. Interestingly, we found that a subset of TE insertion polymorphisms is associated with differential gene expression across accessions. Thus, although not having a global impact on gene expression, distinct TE insertions may contribute to specific gene expression patterns in B. distachyon.Significance statementTransposable elements (TEs) are a major component of plant genomes and a source of genetic and epigenetic innovations underlying adaptation to changing environmental conditions. Yet molecular evidence linking TE silencing and nearby gene expression are lacking for many plant species. We show that in the model grass Brachypodium DNA methylation spreads over very short distances around TEs, with an influence on gene expression for a small subset of TE families.

scholarly journals The Impact of Vegetation on Archaeological Sites in the Low Arctic in Light of Climate Change

ARCTIC ◽  
2020 ◽  
Vol 73 (2) ◽  
pp. 141-152 ◽  
Author(s):  
Henning Matthiesen ◽  
Rasmus Fenger-Nielsen ◽  
Hans Harmsen ◽  
Christian Koch Madsen ◽  
Jørgen Hollesen
Keyword(s):  
Plant Species ◽  
Aerial Photographs ◽  
The Arctic ◽  
Archaeological Sites ◽  
Physical Disturbance ◽  
Vegetation Growth ◽  
Archaeological Preservation ◽  
Low Arctic ◽  
The Moment ◽  
The Impact

Vegetation is changing across the Arctic in response to increasing temperatures, which may influence archaeological sites in the region. At the moment, very little is known about how different plant species influence archaeological remains. In this study we visited 14 archaeological sites stretching across a climatic gradient from the outer coast to the inner fjords in the Nuuk Fjord area of West Greenland to assess the impact of vegetation growth on archaeological preservation. Examination of the physical disturbance of archaeological layers and materials by roots from different plant species showed that horsetail (Equisetum arvense) was particularly destructive because of its deep penetrating rhizomes and ubiquity across the study area. Willow (Salix glauca) also caused physical disturbance due to a dense root network, but its roots were mainly found in the upper 30 cm of the soil. Focus was also given to the impact from vegetation on the visibility of sites, where growth of willow was found be the main problem, especially in the inner fjords. Historic descriptions and aerial photographs from the sites show that shrub growth was already widespread in the region by the 1930s, but photos of some of the sites investigated show that the willow shrubs are significantly taller today, which has decreased the visibility of site features. The impact from horsetail and willow on archaeological sites may be mitigated using geotextiles and grazing by livestock, but both methods require further studies before being implemented in the study area.

scholarly journals Reliable Future Climatic Projections for Sustainable Hydro-Meteorological Assessments in the Western Lake Erie Basin

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 581 ◽  
Author(s):  
Sushant Mehan ◽  
Margaret Gitau ◽  
Dennis Flanagan
Keyword(s):  
Lake Erie ◽  
Transformation Method ◽  
Climate Indices ◽  
Absolute Maximum ◽  
Climate Projections ◽  
Power Transformation ◽  
Climatic Data ◽  
Western Lake ◽  
Rcp 8.5 ◽  
Western Lake Erie

Modeling efforts to simulate hydrologic processes under different climate conditions rely on accurate input data. Among other inaccuracies, errors in climate projections can lead to incorrect decisions. This study aimed to develop a reliable climate (precipitation and temperature) database for the Western Lake Erie Basin for the 21st century. Two statistically downscaled bias-corrected sources of climate projections (GDO: Global Downscaled Climate and Hydrology Projections and MACA: Multivariate Adaptive Constructed Analogs) were tested for their effectiveness in simulating historic climate (1966–2005) using ground-based station data from the National Climatic Data Center. MACA was found to have less bias than GDO and was better at simulating selected climate indices; thus, its climate projections were subsequently tested with different bias correction methods including the power transformation method, variance scaling of temperature, and Stochastic Weather Generators. The power transformation method outperformed the other methods and was used in bias corrections for 2006 to 2099. From the analysis, mean daily precipitation values were expected to remain more or less the same under both RCP (Representative Concentration Pathway) 4.5 and RCP 8.5 scenarios, ranging between 2.4 mm and 3.2 mm, while standard deviations were expected to increase, pointing to a rescaling of the distribution. Maximum one-day precipitation was expected to increase and could vary between 120 and 650 mm across the basin, while the number of wet days could potentially increase under the effects of RCP 4.5 and RCP 8.5. Both mean maximum and mean minimum daily air temperatures were expected to increase by up to 5.0 °C across the basin, while absolute maximum and minimum values could increase by more than 10 °C. The number of days in which precipitation could potentially fall as snow was expected to decrease, as was the annual number of days for optimal corn growth, although an earlier start to the growing season could be expected. Results from this study were very useful in creating a reliable climate database for the entire Western Lake Erie Basin (WLEB), which can be used for hydrologic, water resources, and other applications in the basin. The resulting climate database is published and accessible through the Purdue University Research Repository (Mehan et al., 2019), which is an open-access repository.

Traditional forest protection and woodlots in the coastal savannah of Ghana

2004 ◽  
Vol 31 (3) ◽  
pp. 225-232 ◽  
Author(s):  
MICHAEL O'NEAL CAMPBELL
Keyword(s):  
Plant Species ◽  
Deciduous Forest ◽  
Peer Pressure ◽  
Plant Species Richness ◽  
Geographical Information ◽  
Aerial Photographs ◽  
Sacred Groves ◽  
Forest Protection ◽  
Religiously Based ◽  
Time Series Images

There is increased international interest in religiously based restrictions on land and forest stand use. However, the extent to which so-called sacred groves represent earlier forest ecosystems, and their possible role in biodiversity conservation, are interrelated and complex issues, and neglected in the context of Ghanaian savannahs, which are believed to be in transition from a forested past. Geographical information system (GIS) analysis of time-series images, aerial photographs, statistical analysis of ecological field data and social surveys were used to investigate the Ghanaian savannah. Sacred groves were found to be similar in plant species content and structure to the deciduous forest of southern Ghana. Between 1960 and 1996, these groves experienced far fewer forest losses than unprotected tree stands (<20%, as opposed to up to 100%). Non-sacred groves also contained lower plant species richness and higher numbers of invasive species such as neem (Azadirachta indica A. Juss). Sacred groves, while dependent on respect for religion, local cultural structures and individual peer pressure, offer a role that may support and also be supported by official conservation efforts.

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