Reading past landscapes: combining modern and historical records,maps, pollen-based vegetation reconstructions,and the socioeconomic background

Context

Anthropogenic and environmental changes are reshaping landscapes across the globe. In this context, understanding the patterns, drivers, and consequences of these changes is one of the central challenges of humankind.

Purpose

We aim to test the possibilities of combining modern multidisciplinary approaches to reconstruct the land-cover and linking the changes in land-cover to socioeconomic shifts in southern Estonia over the last 200 years.

Methods

The historical records from five, and maps from six time periods and 79 pollen-based land-cover reconstructions from four lakes are used to determine the land-cover structure and composition and are thereafter combined with the literature based analyses of socioeconomic changes.

Results

All information sources recorded similar changes in the land-cover. The anthropogenic deforestation was comparable to today’s (approximately 50%) during the nineteenth century. Major political and socioeconomic changes led to the intensification of agriculture and maximal deforestation (60–85%) at the beginning of the twentieth century. The land nationalisation following the Soviet occupation led to the reforestation of the less productive agricultural lands. This trend continued until the implementation of European Union agrarian subsidies at the beginning of the twenty first century.

Conclusions

Pollen-based reconstructions provide a trustworthy alternative to historical records and maps. Accounting for source specific biases is essential when dealing with any data source. The landscape’s response to socioeconomic changes was considerable in Estonia over the last 200 years. Changes in land ownership and the global agricultural market are major drivers in determining the strength and direction of the land-cover change.

     

Seasonal Fluxes of Particulate Matter in a Small Closed Lake in Northern Estonia

The seasonal fluxes of dry matter, spheroidal fly-ash particles and pollen were studied in a small mesotrophic lake in order to reveal the patterns of their spatial-temporal distribution in regard to seasonal variations. Sediment traps deployed in the lake at different depths and locationswere used to collect samples for calculating sediment fluxes in two years. The results show that resuspension of settled particles in the lake with a small dynamic ratio is moderate and depends on seasonal changes in thermal stratification. The rate of particle deposition during the summer stratification period was low. The weather conditions during early spring, such as air temperature and the thickness of snow-cover, influence the intensity of resuspension. Air temperature and cloudiness during the summer stratification period determine the rate of bioproduction and thermocline parameters, which also have a major effect on the seston composition and fluxes.     

Effect of storage on the essential oil composition of Piper nigrum L. fruits of different ripening states

The qualitative and quantitative composition of the essential oil from black, green, and white pepper was determined by using a simultaneous distillation and extraction micromethod for oil isolation and gas chromatography (GC)/flame ionization detection (FID) and GC/mass spectrometry (MS) analysis techniques. The most abundant compounds in pepper oils were (E)-beta-caryophyllene (1.4-70.4%), limonene (2.9-38.4%), beta-pinene (0.7-25.6%), Delta-3-carene (1.7-19.0%), sabinene (0-12.2%), alpha-pinene (0.3-10.4%), eugenol (0.1-41.0%), terpinen-4-ol (0-13.2%), hedycaryol (0-9.1%), beta-eudesmol (0-9.7%), and caryophyllene oxide (0.1-7.2%). Green pepper corn obtained by a sublimation drying method gave more oil (12.1 mg/g) and a much higher content of monoterpenes (84.2%) in the oil than air-dried green pepper corn (0.8 mg/g and 26.8%, respectively). The oil from ground black pepper contained more monoterpenes and less sesquiterprnes and oxygenated terpenoids as compared to green and white pepper oils. After 1 year of storage of pepper samples in a glass vessel at room temperature, the amount of the oils isolated decreased, the content of terpenes decreased, and the amount of oxygenated terpenoids increased. Differently from other pepper samples, 1 year storage of green pepper corn raised the oil amount more than twice of both drying methods.     

Characteristic Fly-ash Particles from Oil-shale Combustion Found in Lake Sediments

Fly-ash particles accumulate in sediments and can be used to assess spatial distribution and temporal trends of atmospheric deposition of pollutants derived from high temperature combustion of fossil fuels. Previous work has concerned fly-ash derived from oil and coal. Oil-shale is the main fossil fuel used in Estonia and a major source of atmospheric pollution in the Baltic states. To assess if oil-shale power plants produce specific fly-ash particles, we used scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) to compare fly-ash particles from oil-shale combustion with particles from oil and coal combustion. Two types were analysed, large black (10–30 μm) and small glassy (<5 μm) spheroidal particles. Although particle morphology to some extent is indicative of the fuel burnt, morphological characters are not sufficient to differentiate between particles of different origin. However, our results indicate that with EDX analysis the fly-ash from oil-shale can be distinguished from oil and coal derived particles in environmental samples. Concentrations of large black and small glassy spheroidal fly-ash particles in a sediment core from an Estonian lake showed similar trends to oil-shale combustion statistics from Estonian power plants.     

A comparative analysis of decline in the distribution ranges of orchid species in Estonia and the United Kingdom

National databases were interrogated to analyse and compare proportional alterations in the distribution ranges of orchid species between two surveys in the UK (surveys completed in 1969 and 1999) and in Estonia (surveys completed in 1970 and 2004). Nearly every species declined between the surveys in both countries, and two species may have become extinct in the UK. Mean decline in distribution range for 49 species in the UK was 50% (range 14-100%), and 23 species declined by over 50%. The mean decline for 33 orchid species in Estonia was 25% (range 0-62%), and three species declined by over 50%. These results corroborate serious range declines recently reported for orchids in other regions of Europe (the Netherlands and Flanders, Belgium). In contrast with these other regions, we found that species associated with calcareous grassland and woodland habitats had suffered greater mean contractions in range than species of wet grassland habitats. Greater decline was recorded for species found on drier soils, and for species characteristic of open habitats. In addition, greater decline was found in species with short inflorescences, and in species that were short-lived, and clonal. Our results suggest that levels of decline shown both by groups of species associated with specific habitat types, and by particular species of orchid, depend strongly on local policies and specific conservation action, and indicate the habitat types on which conservation efforts may need to be concentrated in the future. The results suggest that grazing and mowing of competing vegetation, and avoidance of substrate disturbance, will produce the greatest rewards for the most vulnerable species.     

Porcine proliferative enteropathy in Estonian pig herds: histopathology and detection of Lawsonia intracellularis by PCR

Lawsonia intracellularis is the causative agent of proliferative enteritis in pigs (PPE). This bacterium is difficult to culture from clinical samples and antemortem demonstration is therefore usually performed by PCR on faecal samples. The aim of this study was to elucidate the frequency of L. intracellularis infection in pig herds in Estonia using PCR, histopathological methods and electronmicroscopical studies. The frequency of demonstration of L. intracellularis was highest in 9-12 weeks old pigs (68.1%). It was more frequent in growing pigs with enteritis on small farms where the system of "all-in all-out" was not practiced and where standards of hygiene were poor. Gross and histopathological studies demonstrated that characteristic macroscopic changes associated with PPE were localised to the distal jejunum and ileum.Thickened longitudinal and circumferential folds occurred in the mucosa of the affected regions of the bowel. Samples from pigs aged 4 to 20 weeks exhibited the most intensive inflammatory changes. The distal part of the jejunum, ileum and the upper third of proximal colon and cecum wall were visibly thickened with reduced luminal diameter. Hyperplasia of lymphoid tissue and, in many cases, pseudomembranous or fibrinous inflammation was found. L. intracellularis was detected in 56 young pigs using histopathological methods. Additionally, in 8 of these pigs intracellular bacteria were demonstrated in ilial epithelial cells by transmission electronmicroscopical (TEM) investigation. On the basis of these TEM investigations it was concluded that L. intracellularis causes disturbances of normal growth, differentiation and apoptosis of the epithelial cells of ileum.     

The Spatial Distribution of Characterised Fly-Ash Particles and Trace Metals in Lake Sediments and Catchment Mosses: Estonia

The concentrations of fly-ash particles were studied in the surface sediments of 42 lakes in Estonia. Concentrations of both spheroidal carbonaceous particles (SCPs) and inorganic ash spheres (IASs) were determined and the particles chemically characterised to different fuel types. This was accompanied by trace metal analyses from lake surface sediments and catchment mosses in order to determine the distribution of atmospheric pollutants. The obtained spatial distribution data for fly-ash particles varied to a great extent, partly due to differences in sedimentation rates but mainly due to higher deposition in industrial areas. The distribution patterns of the different particle types in lake sediments, as well as the trace metals in mosses, show that the deposition of airborne particulates is of local origin around pollution sources and that the share of long-range transported atmospheric impurities is high along the main cyclonic routes in Estonia.     

Fluorescence spectroscopy of sedimentary pore-water humic substances: a simple tool for retrospective analysis of lake ecosystems

Purpose

The feasibility of applying the method of single-scan fluorescence emission spectra of humic substances (HSs) without chemical pretreatments of sediment pore-water samples was tested to ascertain the past productivity and sources of organic matter of lakes.

Materials and methods

Sediment samples were collected from ten Estonian lakes (located between 57°36′ and 59°25′N and 22°12′ and 26°59′E) covering all levels of the trophic scale. The height (fluorescence intensity), location (fluorescence maximum) and shape (fluorescence index, the ratio of intensities at the emission wavelengths 450 and 500 nm) of the fluorescence emission spectrum at an excitation of 340 nm were under consideration.

Results and discussion

Pore-water humic substances (pwHSs) from sediments of eutrophic lakes had generally a high fluorescence intensity and fluorescence index and their fluorescence maximum was located at shorter wavelengths. Characteristic features of pwHSs from oligotrophic lakes were low fluorescence intensity, emission of maximum fluorescence at shorter wavelengths and high fluorescence index values. Pore-water humic substances from sediments of dystrophic lakes were characterized by a low fluorescence intensity and fluorescence index and their spectral peak was shifted to longer wavelengths. The study also demonstrated that a shift in the peak location of pwHSs fluorescence was accompanied with a change in the C/N ratios of sedimentary organic matter, and the alteration in the fluorescence index of pwHSs was synchronous with the changes in their molecular weight.

Conclusions

The obtained results suggest that fluorescence spectroscopy of pwHSs without using chemical pretreatments has a great potential in the reconstruction of past lake conditions.