scholarly journals Floristic Diversity of Lakes Subjected to Long Term Changes in the Water Network of the West Polesie (Eastern Poland)

2017 ◽  
Vol 19 (3) ◽  
pp. 1-16
Author(s):  
Joanna Sender ◽  
Weronika Maślanko
Keyword(s):  
Water Surface ◽  
Peat Bogs ◽  
Floristic Diversity ◽  
Water Network ◽  
The West ◽  
Natural Lakes ◽  
Hydrological Changes ◽  
Long Term Changes

Abstract The Wieprz-Krzna Canal, built in 1961, is one of the longest in Poland (142 km). Although the drainage construction was intended to revitalize the region of wetlands and peat-bogs of the West Polesie, it caused large hydrological changes. Research on catchments of three natural lakes and three retention reservoirs involved cartographic analysis using photointerpretation, as well as the Braun-Blanquet method. In the studied area, between 1939 and 2016 the length of rivers and ditches increased more than three times. Macrophytes covered about 20-27% of the natural lakes water surface, whereas in retention reservoirs the coverage was 12-15.5%. Also a greater diversity of macrophytes occurred in natural lakes. In retention reservoirs it was restricted to only emerged macrophytes.

scholarly journals Long-Term Changes in Floristic Diversity as an Effect of Transforming the Lake into a Retention Reservoir

2021 ◽  
Vol 13 (14) ◽  
pp. 7642
Author(s):  
Joanna Sender ◽  
Danuta Urban ◽  
Monika Różańska-Boczula ◽  
Antoni Grzywna
Keyword(s):  
Drainage System ◽  
High Water ◽  
Diversity Indices ◽  
Habitat Diversity ◽  
Peat Bogs ◽  
Ecological Index ◽  
Natural Lakes ◽  
Lighting Conditions ◽  
Low Reaction Temperature

The Łęczna-Włodawa Lake District is one of the most valuable natural regions in Europe. It is an area of numerous lakes, peat bogs, swamps and forests, which has been undergoing intensive transformation for decades. Among the largest projects were the creation of the Wieprz Krzna Canal system along with the drainage system and the transformation of natural lakes into retention reservoirs. Among the transformed lakes is Lake Wytyckie. The land was used for analyses near the lake, and floristic and habitat analyses were carried out within the boundaries of the contemporary embankment. The studies were carried out from the 1950s, when the lake functioned as a natural reservoir, through to the 1980s (the transformation of the lake), to the 2020s. Lake Wytyckie was transformed into a retention reservoir by increasing its size and flooding the areas inhabited mainly by peat bog, meadow and forest vegetation, which contributed to the impoverishment of both species and habitat diversity of the area, while it increased the nutrient richness of the water. This was reflected both in the decline in the value of individual diversity indices as well as in the ecological index numbers. In the first period of the research, the area was dominated by wetlands, not drained, with a large variety of species that preferred good lighting conditions. Additionally, the habitat was characterized by low reaction, temperature and trophic values. In the following period, there was an increase in the depth of the water of the reservoir, characterized by high water visibility values, which contributed to the presence of protected species, as did the low moisture content of the areas within the embankment and a neutral pH. The factors currently influencing the formation of the vegetation structure are the high humidity of the entire embankment area, the increase in pH, and the significant increase in the share of built-up areas in the immediate vicinity.

scholarly journals Long-term changes of the ice regime of rivers in Latvia

2016 ◽  
Vol 47 (4) ◽  
pp. 782-798
Author(s):  
Inese Latkovska ◽  
Elga Apsīte ◽  
Didzis Elferts
Keyword(s):  
Regional Differences ◽  
Severity Index ◽  
Ice Cover ◽  
Ice Thickness ◽  
Positive Trend ◽  
The West ◽  
Climate Conditions ◽  
Long Term Changes ◽  
Ice Regime

The ice regime of rivers is considered a sensitive indicator of climate change. This paper summarises the results of research on the long-term changes in the ice regime parameters under changing climate conditions and their regional peculiarities in Latvia from 1945 to 2012. The ice cover duration on Latvian rivers has decreased during recent decades. The research results demonstrated that there is a positive trend as regards the formation of the ice cover and in 31.8% of the cases the trend is statistically significant at p < 0.05. As regards the breaking up of ice, there is a statistically significant negative trend in 93.2% of the cases at p < 0.05. This indicates an earlier ice break-up date, which in turn, displays a strong correlation with the increase of the air temperature. The same pattern applies to the reduction of the length of ice cover (a statistically significant trend in 86.4% of the cases at p < 0.05). In approximately 60% of the cases, there is a statistically significant reduction of the ice thickness. The estimated winter severity index indicates warmer winters over the last 20 years as well as regional differences in the west–east direction.

scholarly journals Variability and past long-term changes of brominated very short-lived substances at the tropical tropopause

2020 ◽  
Vol 20 (11) ◽  
pp. 7103-7123
Author(s):  
Susann Tegtmeier ◽  
Elliot Atlas ◽  
Birgit Quack ◽  
Franziska Ziska ◽  
Kirstin Krüger
Keyword(s):  
Central America ◽  
Temporal Variability ◽  
Spatial And Temporal Variability ◽  
Positive Trend ◽  
The West ◽  
West Pacific ◽  
Mixing Ratios ◽  
Long Term Changes ◽  
Averaged Model

Abstract. Halogenated very short-lived substances (VSLSs), such as bromoform (CHBr3), can be transported to the stratosphere and contribute to the halogen loading and ozone depletion. Given their highly variable emission rates and their short atmospheric lifetimes, the exact amount as well as the spatio-temporal variability of their contribution to the stratospheric halogen loading are still uncertain. We combine observational data sets with Lagrangian atmospheric modelling in order to analyse the spatial and temporal variability of the CHBr3 injection into the stratosphere for the time period 1979–2013. Regional maxima with mixing ratios of up to 0.4–0.5 ppt at 17 km altitude are diagnosed to be over Central America (1) and over the Maritime Continent–west Pacific (2), both of which are confirmed by high-altitude aircraft campaigns. The CHBr3 maximum over Central America is caused by the co-occurrence of convectively driven short transport timescales and strong regional sources, which in conjunction drive the seasonality of CHBr3 injection. Model results at a daily resolution reveal isolated, exceptionally high CHBr3 values in this region which are confirmed by aircraft measurements during the ACCENT campaign and do not occur in spatially or temporally averaged model fields. CHBr3 injection over the west Pacific is centred south of the Equator due to strong oceanic sources underneath prescribed by the here-applied bottom-up emission inventory. The globally largest CHBr3 mixing ratios at the cold point level of up to 0.6 ppt are diagnosed to occur over the region of India, Bay of Bengal, and Arabian Sea (3); however, no data from aircraft campaigns are available to confirm this finding. Inter-annual variability of stratospheric CHBr3 injection of 10 %–20 % is to a large part driven by the variability of coupled ocean–atmosphere circulation systems. Long-term changes, on the other hand, correlate with the regional sea surface temperature trends resulting in positive trends of stratospheric CHBr3 injection over the west Pacific and Asian monsoon region and negative trends over the east Pacific. For the tropical mean, these opposite regional trends balance each other out, resulting in a relatively weak positive trend of 0.017±0.012 ppt Br per decade for 1979–2013, corresponding to 3 % Br per decade. The overall contribution of CHBr3 together with CH2Br2 to the stratospheric halogen loading accounts for 4.7 ppt Br, in good agreement with existing studies, with 50 % and 50 % being injected in the form of source and product gases, respectively.

scholarly journals Variability and long-term changes of brominated VSLS at the tropical tropopause

2019 ◽  
Author(s):  
Susann Tegtmeier ◽  
Elliot Atlas ◽  
Birgit Quack ◽  
Franziska Ziska ◽  
Kirstin Krüger
Keyword(s):  
Central America ◽  
Spatial And Temporal Variability ◽  
Positive Trend ◽  
The West ◽  
Asian Monsoon Region ◽  
West Pacific ◽  
Mixing Ratios ◽  
Long Term Changes ◽  
Averaged Model

Abstract. We combine available observational data sets with Lagrangian atmospheric modelling in order to analyze the spatial and temporal variability of the CHBr3 injection into the stratosphere. Regional maxima with mixing ratios of up to 0.4–0.5 ppt at 17 km altitude are diagnosed to be over Central America (1) and over the Maritime Continent/West Pacific (2), both of which are confirmed by high-altitude aircraft campaigns. The CHBr3 maximum over Central America is caused by the co-occurrence of convectively-driven short transport time scales and strong regional sources, which in conjunction drive the seasonality of CHBr3 injection. Model results at a daily resolution reveal isolated, exceptionally high CHBr3 values in this region which are confirmed by measurements during the ACCENT campaign and do not occur in spatially or temporally averaged model fields. CHBr3 injection over the West Pacific is centered south of the equator due to strong oceanic sources underneath prescribed by the here applied bottom-up emission inventory. The globally strongest stratospheric CHBr3 injection of up to 0.6 ppt is diagnosed to occur over the region of India, Bay of Bengal and Arabian Sea (3), however, no data from aircraft campaigns are available to confirm this finding. Interannual variability of stratospheric CHBr3 injection of 10–20 % is to a large part driven by the variability of coupled ocean-atmosphere circulation systems. Long-term changes, on the other hand, correlate with the regional SST trends resulting in positive trends of stratospheric CHBr3 injection over the West Pacific and Asian monsoon region and negative trends over the East Pacific. For the tropical mean, these opposite regional trends balance each other out resulting in a relatively weak positive trend of 0.017 ± 0.012 ppt Br/dec for 1979–2013, corresponding 3 % Br/dec. The overall contribution of CHBr3 together with CH2Br2 to the stratospheric halogen loading accounts for 4.7 ppt Br, in good agreement with existing studies, with 50 %/50 % being injected in form of source and product gases, respectively.

scholarly journals Long-term changes in regional vegetation cover along the west coast of southern Norway: The importance of human impact

2018 ◽  
Vol 29 (3) ◽  
pp. 404-415 ◽  
Author(s):  
Kari Loe Hjelle ◽  
Lene S. Halvorsen ◽  
Lisbeth Prøsch-Danielsen ◽  
Shinya Sugita ◽  
Aage Paus ◽  
...  
Keyword(s):  
Human Impact ◽  
West Coast ◽  
Vegetation Cover ◽  
The West ◽  
Long Term Changes ◽  
Southern Norway

scholarly journals Long-term changes in the snow–firn pack stratigraphy on Ürümqi glacier No. 1, eastern Tien Shan, China

2007 ◽  
Vol 46 ◽  
pp. 331-334 ◽  
Author(s):  
Feiteng Wang ◽  
Zhongqin Li ◽  
R. Edwards ◽  
Huilin Li
Keyword(s):  
Ablation Rate ◽  
Tien Shan ◽  
Coarse Grained ◽  
Climatic Warming ◽  
The West ◽  
Branch Site ◽  
Snow Stratigraphy ◽  
Long Term Changes ◽  
The Mean

AbstractWe report on changes to the snowpack of Ürümqi glacier No. 1, eastern Tien Shan, China, resulting from climate change between 1961 and 2005. Data from more than 120 snow pits were used to investigate temporal changes in the snow stratigraphy for three periods 1961–62, 1980–83 and 2002–05. Both the thickness and structure of the snow were found to be significantly altered by climatic warming. The proportion of coarse-grained firn, which is usually formed by infiltration water, was found to have increased from 40% to 65% over the period 1961–2005, and the distribution of the glacier zones also changed significantly, with all boundaries moving up-slope. The recrystallization–infiltration zone disappeared in 1989. The mean ablation rate over the melt season increased by ~26% from 1962 to 1980 at the west branch site and by ~75% from 1980 to 2004 at the east branch site.

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