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Phenological response of flood-plain forest ecosystem during 1961-2011
Bartošová, Lenka ; Trnka, Miroslav ; Bauer, Z. ; Štěpánek, P. ; Možný, M. ; Žalud, Zdeněk
The presented study is focused on 50 years of phenological observations (1961–2011) of the herbs, shrubs, trees and bird populations and the phenological phases that create a continuous phenological sequence covering the whole spring aspect of the fl oodplain forest ecosystem. Th e phenological phases were observed for 5 herbs, 5 shrubs, 3 trees and 2 bird species. Th e phenological phases were observed as precisely as possible by only one observer during the whole time of observation. All observed plants and bird species showed statistically signifi cant shift s to the earlier time but the rate of shift ing among the parts of the fl ood-plain forest ecosystem was diff erent. Th e most progressive shift s were detected for herbs (the rate of shift ing was on average 13.9 days), followed by shrubs (phenophases advanced by 11.3 days on average), trees (phenophases advanced by 10.2 days) and fi nally by bird species (phenophases advanced by 9.6 days on average). Consequently the length of overlap of the chosen phenological phases was elaborated. Th e rate of shortening or lengthening of the overlap diff ers among all parts of the ecosystem and indicates not only the separation of phenophases but also no statistically signifi cant change in the length of overlap in each part of the ecosystem.
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Quality control and homogeneity testing of daily time series of eca ECA&D
Zahradníček, Pavel ; Štěpánek, Petr ; Farda, Aleš ; Skalák, Petr
For any meaningful climate analysis, it is necessary for analysed time series to be homogeneous, which means that their variations are caused solely by variations in weather and climate (Conrad and Pollak 1950). Th us, prior to any analysis, the need to homogenize data and check their quality arises. Unfortunately, most of the climatological series that span over decades, to centuries, contain inhomogeneities caused by station relocations, exchange of observers, changes in the vicinity of the stations (e.g. urbanization), changes in instruments, observing practices (e.g. diff erent formulas for calculating daily means, diff erent observation times), etc. In this work we focused on testing the quality and homogeneity of daily data produced by ECA&D. Th is is a free available dataset of daily meteorological elements from the European Climate Assessment & Dataset (http://eca.knmi.nl/). Th is database was used to create a regular grid of EOBS points, which are oft en used to validate climate models.
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Spatial heterogeneity of soil CO2 efflux in four different ecosystems
Dařenová, Eva
Manual measurements of soil CO2 effl ux on a larger number of positions can give precise estimation of CO2 effl ux from the investigated area and together with temporal dynamics, observed in continuous measurements, can provide a good view on the ecosystem carbon balance. In this study we investigated the spatial heterogeneity of soil CO2 effl ux in four diff erent ecosystems (spruce forest, beech forest, wetland, grassland). Soil CO2 was measured on a net of 25–65 positions using a manual measurement system. We tried to fi nd responsible factors for the heterogeneity and to determine a measurement protocol for the most precise estimation of soil CO2 effl ux. Th e highest respiration activity was observed in the spruce forest, the lowest in the wetland ecosystem, where it was caused by a high water table. In the wetland ecosystem, there was the highest spatial heterogeneity of respiration activity, which reached almost 60 %. Th is high heterogeneity was caused by the gradient of the water table depth. Contrary to this, the lowest heterogeneity was found in the grassland where it was only about 15 %. In the spruce and beech forest the heterogeneity ranged between 35 and 45 %. As infl uencing factors we investigated e.g. soil moisture, tree distance and amount of the above ground biomass.
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Natural disturbances in central-european mountain spruce forests. A basis for forest restoration
Edwards-Jonášová, Magda ; Čermák, Martin
Risk of natural disturbances is a frequently discussed topic in the context of mountain spruce forests and global climate change. Recently, large-scale natural disturbances such as bark beetle outbreaks and windfalls have appeared relatively more frequently in Central-European mountain spruce (Picea abies L.) forests, which led to the enforcement of salvage logging even in some protected areas. Our study was performed as part of a long-term observation of recovery of spruce forests aff ected by bark beetle and windfall with and without interventions in two Central-European national parks, Šumava National Park in the Czech Republic and Tatra National Park in Slovakia. Th e results proved the ability of spruce forests to recover unassisted even from stand-replacing natural disturbances. Th eir biological legacies, which include standing and lying dead wood, are important for natural regeneration of tree species, and provide critical habitats for particular forest species. In comparison to natural disturbances, the artifi cial disturbances resulting from salvage logging destroyed a substantial part of the natural regeneration, which led to the need for artifi cial reforestation. Th us, the non-intervention strategy appears to be the best option for restoration of disturbed forests in the zone of mountain spruce forests. Based on our results, we propose that natural disturbances be considered as a basis for forest regeneration and restoration of their natural structure.
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Remotely sensed NDVI as a support tool for agricultural drouhgt assessment
Hlavinka, Petr ; Semerádová, Daniela ; Trnka, Miroslav ; Lukas, V. ; Bohovic, R. ; Balek, J. ; Wardlow, B. ; Hayes, M. ; Tseagaye, T. ; Žalud, Zdeněk
Th e main aim of the submitted study was to introduce how the remotely sensed NDVI (Normalized Diff erence Vegetation Index) could be used for agricultural drought assessment within the Czech Republic. Th e relationship between NDVI values and observed yields of spring barley and winter wheat was analyzed for selected districts. Moreover the ability of NDVI (at district level in the form of seasonal greenness – SG) to explain the water balance or drought occurrence and severity was tested. For this purpose a data mining technique was used. A relative form of the Palmer Drought Severity Index (rPDSI) was used as a dependent variable to indicate drought occurrence. A Standardized Precipitation Index (SPI), percentage of average SG (PASG), Start of Season Anomaly (SOSA) and district identifi cation were used as independent variables. MODIS (Moderate Resolution Imaging Spectroradiometer) observations from the Terra satellite were used as a source of NDVI. Th e situation within 6 selected districts (Olomouc, Přerov, Znojmo, Břeclav, Žďár nad Sázavou and Havlíčkův Brod) during the period from 2000 to 2012 was analyzed. Promising results were achieved, so practical use of this approach (e.g. for spatial and temporal assessment of drought stress within the vegetation) could be expected.
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Towards the issue of ecosystem services of small watercourses in the Czech Republic
Jakubínský, Jiří
Th e issue of ecosystem services represents a hot topic especially in connection with quantitative expression of their values and research of functions, which the landscape provides to a human society. Th e question of ecosystem values research is solved with a focus on the river landscape, defi ned as the ecosystem along watercourses whose functioning is directly conditioned by the presence of the hydrographical network. Since it is a very attractive area for the implementation of human needs, there is oft en what is seen as a confl ict between activities of human society and the eff ects of natural processes. Catchment areas of small watercourses or their parts which are specifi c in terms of mutually diff erent intensity of anthropogenic pressure on the landscape were selected as the model sites. Th e main aim of this paper is to analyse the relationship between the value of landscape ecosystem services – either usage of existing methodologies for ecosystem valuation, the rate of small watercourse degradation and changes in their natural parameters (morphology of the river channel and riparian zones).
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Precipitation variability in the czech land since ad 1500. How strong is the signal contained within documentary sources?
Dobrovolný, Petr ; Brázdil, Rudolf ; Trnka, Miroslav ; Kotyza, O. ; Valášek, H.
Past climate may be reconstructed from a number of proxies. Some of them are “natural archives”, such as tree rings, ice cores and boreholes, most of which are sensitive to air temperature. Other valuable information can be also found in “man-made archives”. Various sources of documentary data very oft en refer not only to temperature but also to other aspects of past weather and climate, such as dry and wet periods. We use the long and homogeneous precipitation series from the recent instrumental period to calibrate precipitation indices derived from older documentary sources. Th e primary objective of this contribution is to provide a quantitative reconstruction of precipitation in the Czech Lands for the last 500 years. Calibration and verifi cation statistics are used to evaluate the strength of the signal. Reconstructed precipitation series are compared with similar Central European documentary-based reconstructions, as well as with reconstructions based on a range of natural proxies.
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Climate change impacts and migration in Bangladesh
Stojanov, Robert ; Ullah, A. ; Duží, Barbora ; Vikhrov, Dmytro
Climate change (variability) is a set of changes in the climatic system and regardless of whether it is caused by natural or anthropogenic infl uence, external or internal factors or mutual combinations, it has serious eff ects on patterns of livelihood activities and the quality of life in many regions around the world. Th is paper explores migration as an adaptation and coping strategy of people living in climate change aff ected areas in South Bangladesh. Th e occurrence of diff erent fl ood types and their impacts on the quality of human life are analysed as well as the various adaptation techniques and activities used to cope with risks of climate change. Th e paper is based on the results of a fi eld survey conducted in localities in South Bangladesh.
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Droughts in the Czech Lands during 18th century
Brázdil, Rudolf ; Řezníčková, Ladislava ; Kotyza, O. ; Valášek, H. ; Dobrovolný, Petr
Th is paper addresses dry episodes and droughts in the Czech Lands during the 18th century. It is based on various types of documentary evidence, including data describing phenomena related to drought patterns, from the occurrence of precipitation (or lack of it) to derived impacts (bad yields, water shortages, drying watercourses, etc.). Th e documentary data include various degrees of detail, but their interpretation allows work at the level of monthly resolution. Dry conditions for at least two consecutive months in a given year were considered as drought for our purposes. A total of 49 years with droughts were derived from documentary data, with the prevailing occurrence of dry months in the summer half-year (April–September: 66.0%) associated with the most severe impacts. Th is shows that probably all the droughts with two-year re-occurrence intervals were identifi ed from the documentary data available. As examples of impacts and their territorial extent, some years with severe droughts in the eastern part of the Czech Lands, Moravia, are described (1718, 1719, 1726, 1746, and 1790). Th e results obtained are an important contribution to the more broadly-oriented study of droughts in the Czech Lands during the past 500 years based on documentary and instrumental data.
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Past hydrometeorological extremes in south-western Moravia (Czech republic) derived from taxation records
Chromá, Kateřina ; Brázdil, Rudolf ; Valášek, H. ; Zahradníček, Pavel ; Dolák, L.
Historical records related to taxation at fi ve landed estates located in the south-western part of Moravia in today’s Czech Republic are employed for the study of hydrological and meteorological extremes during the 1761–1900 period. At that time, the tax system in Moravia allowed farmers to request tax relief if their crops or land were damaged by natural disaster. Th is study disclosed a total of 69 hydrometeorological events resulting in damage in the 1761–1900 period, with the highest concentration of extreme events in 1771–1799 and 1822– 1849 (together 82.6%). Of 113 extremes classifi ed, torrential rains (34.5%) and hailstorms (31.9%) were the most frequent, followed by thunderstorms, fl oods, windstorms and fl ash fl oods. June (30.4%) was the month with the highest occurrence of extreme events and July (31.0%) for classifi able extremes; in both cases their highest frequency occurred in May–August. However, the results obtained are infl uenced by uncertainties related to taxation records, such as temporal and spatial incompleteness or limitation of the vegetation period, as well as by the local occurrence of the phenomena studied, a trend demonstrated by comparison with the results of Dolák et al. (2013). Taxation records constitute a very important source of data for historical climatology and hydrology.
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