Grid Mapping of Flora and Its Employment at Various Spatial Scales

Katedra botanikyDepartment of BotanyPřírodovědecká fakultaFaculty of Scienc

Loss factor estimation of the layered panels

The loss factor identification is the effective way to get the proper acoustic analysis in the virtual environment. Using the predictive model is a necessary part of the virtual development. The detection of the inappropriate materials or malfunction designs in the early phase of product development and can dramatically save the cost and development time. The loss factor is the nonlinear parameter for the material modeling of the noise suppression during acoustic analysis. The identification of the loss factor is necessary to perform on the real specimen. The Decay Rate Method is the effective methodology to get accurate results by using standard measuring equipment and is ideal to use in-situ environment. The article describes loss factor identification for plywood material and applications for the automotive industry for glass materials. The complete results analysis is confidential, but the overall procedure of the method is described in specimen analysis

Loss factor estimation of the plywood materials

The acoustic analysis in virtual environment enables the design optimization in the earlier phase of the new product development in term of the noise suppression of the structure. The structural material damping behavior is the most important parameter for the predictive acoustic simulations. The method for the damping loss factor identification involves the measurement of the real specimen and post-processing analysis. The result of the estimation is the structural damping behavior of plywood materials needed for the virtual acoustic analysis

Dark side of the fence: ornamental plants as a source of wild-growing flora in the Czech Republic

Ornamental plants constitute an important source of alien, and potentially invasive species, but also include a substantial part of native flora and consist of taxa that occur both in the wild and in cultivation; yet garden floras are largely ignored in ecological studies.We studied ornamental plants in the Czech Republic in order to provide detailed information, based on field sampling, on the diversity of taxa grown in cultivation in private gardens. Sampling was done in accessible public areas, private gardens and private areas in villages, town- and city neighbourhoods, garden allotments, cemeteries, areas of dispersed farmhouse settlements not accessible to the public, and in new urban sprawl. The data can be used to estimate the propagule pressure of individual taxa, measured in terms of the frequency with which they are planted in the gardens. To make the data comparable across sites, we adopted a two-level approach that resulted in producing a detailed list (including all the taxa recorded) and an aggregated list (merging closely related and similar taxa, which was necessary in order to assess the frequency of planting across sites). Each species on the detailed list was assigned an origin, status, life history and cultivation requirements. Comparing the field records with national checklists of both native and alien vascular plants we quantified particular components of the ornamental flora. The floristic inventories for 174 sites yielded 1842 taxa on the detailed list, consisting of 1642 species (standard binomials), 9 cultivars assigned to genera, 147 hybrids and hybridogenous taxa, and 44 taxa identified at higher than species level. Of these taxa 1417 (76.9%) were alien and 420 (22.8%) native. The ornamental flora consisted of not-escaping aliens, escaping aliens and cultivated natives. Of the recorded taxa, 841 (45.6%) occur both in cultivation and the wild. The aggregated list comprised 1514 taxa and resulted from merging 533 taxa from the detailed list into 205 taxa. Most alien ornamentals are native to Asia and Americas. The proportion of escaped and not-escaping aliens significantly differed from wild aliens in the spontaneous flora with underrepresentation of escaped, which originated from Australia, Africa and the Mediterranean area. Taxa from Africa and anecophytes were overrepresented and those from Australia, the Mediterranean and other parts of Europe underrepresented among not escaping aliens. The assessment of planting frequency revealed that 270 taxa were found at more than 25% of the sites, while 584 (40%) occurred at only one or two sites.Winter annuals and shrubs are most represented among the commonly planted aliens; the only native species with comparably high planting frequencies among the aliens, are Vinca minor, Hedera helix and Aquilegia vulgaris. Related to the invasion potential of ornamental garden flora we analysed the recorded taxa with respect to the transient/persistent character of their occurrence. The core (persistent) part of the flora comprised 599 taxa (32% of the total number of taxa) and the transient 240 (13%) taxa. The “grey zone” between the two included 1003 taxa (55%). The results reported here provide quantitative insights into the role of horticulture as a major pathway of plant invasions

Paleomeander at the Northern bailey of the archaeological site Pohansko near Břeclav

The site is situated in the bottomland near the confluence of Dyje and Morava rivers. The junction area is split by many sides and inactive channels. The human impact (settlement establishment, deforestation and landscape management) is also reflected in the bottomland development. Processes lead to erosion, accumulation of sediments in river beds and changes in vegetation. One of the peaks of the settlement of the studied area can be considered during existence of the Great Moravian Empire when the settlement agglomerations developed directly in the floodplain. The area has been intensively archaeologically studied for a long time. In the context of the ongoing climate change and increasing intensity of floods the relationship between climate, natural conditions and the functioning of the human settlements comes to the forefront of scientific interest. For the reconstruction of the complicated floodplain development a combination of different research methods was used. For direct determination of stratigraphy an excavated transect through the sediments connecting the edge of the settlement (in the area of the so called Northern bailey) on the sand elevation („hrúd“) and lower flood-plain step in the area of presumptive paleomeander has been studied. Direct field documentation and palynological and sedimentological studies and 14C dating method were utilized. These methods have been supplemented by remote sensing methods: Geophysics (ERT, DEMP), Lidar. On their basis a digital relief model (extend of measured area was 54 000 m2) was created as well as a map of conductivity anomalies. The study documented a sequence of extinct riverbeds (a series of fluvial point bars) of various ages at the northern edge of Pohansko. Their stratigraphic position proves the stage when the active channel was eroding the edge of the archaeological site. The sediments stored in previous periods were destroyed by erosion in this space. The aggradation of the floodplain occurred in 14th–16th century. Results of pollen analysis indicate the presence of a mosaic of forested and open landscape of mesophilous alluvial woodlands and open areas. The immediate vicinity of the sedimentary area was not too much affected by agricultural activity at that time. Compared to palynospectra from sediments of the Great Moravian settlement, the deforestation intensity and the proportion of anthropogenic indicators were noticeably lower.The site is situated in the bottomland near the confluence of Dyje and Morava rivers. The junction area is split by many sides and inactive channels. The human impact (settlement establishment, deforestation and landscape management) is also reflected in the bottomland development. Processes lead to erosion, accumulation of sediments in river beds and changes in vegetation. One of the peaks of the settlement of the studied area can be considered during existence of the Great Moravian Empire when the settlement agglomerations developed directly in the floodplain. The area has been intensively archaeologically studied for a long time. In the context of the ongoing climate change and increasing intensity of floods the relationship between climate, natural conditions and the functioning of the human settlements comes to the forefront of scientific interest. For the reconstruction of the complicated floodplain development a combination of different research methods was used. For direct determination of stratigraphy an excavated transect through the sediments connecting the edge of the settlement (in the area of the so called Northern bailey) on the sand elevation („hrúd“) and lower flood-plain step in the area of presumptive paleomeander has been studied. Direct field documentation and palynological and sedimentological studies and 14C dating method were utilized. These methods have been supplemented by remote sensing methods: Geophysics (ERT, DEMP), Lidar. On their basis a digital relief model (extend of measured area was 54 000 m2) was created as well as a map of conductivity anomalies. The study documented a sequence of extinct riverbeds (a series of fluvial point bars) of various ages at the northern edge of Pohansko. Their stratigraphic position proves the stage when the active channel was eroding the edge of the archaeological site. The sediments stored in previous periods were destroyed by erosion in this space. The aggradation of the floodplain occurred in 14th–16th century. Results of pollen analysis indicate the presence of a mosaic of forested and open landscape of mesophilous alluvial woodlands and open areas. The immediate vicinity of the sedimentary area was not too much affected by agricultural activity at that time. Compared to palynospectra from sediments of the Great Moravian settlement, the deforestation intensity and the proportion of anthropogenic indicators were noticeably lower

Responses of competitive understorey species to spatial environmental gradients inaccurately explain temporal changes

Understorey plant communities play a key role in the functioning of forest ecosystems. Under favourable environmental conditions, competitive understorey species may develop high abundances and influence important ecosystem processes such as tree regeneration. Thus, understanding and predicting the response of competitive understorey species as a function of changing environmental conditions is important for forest managers. In the absence of sufficient temporal data to quantify actual vegetation changes, space-for-time (SFT) substitution is often used, i.e. studies that use environmental gradients across space to infer vegetation responses to environmental change over time. Here we assess the validity of such SFT approaches and analysed 36 resurvey studies from ancient forests with low levels of recent disturbances across temperate Europe to assess how six competitive understorey plant species respond to gradients of overstorey cover, soil conditions, atmospheric N deposition and climatic conditions over space and time. The combination of historical and contemporary surveys allows (i) to test if observed contemporary patterns across space are consistent at the time of the historical survey, and, crucially, (ii) to assess whether changes in abundance over time given recorded environmental change match expectations from patterns recorded along environmental gradients in space. We found consistent spatial relationships at the two periods: local variation in soil variables and overstorey cover were the best predictors of individual species’ cover while interregional variation in coarse-scale variables, i.e. N deposition and climate, was less important. However, we found that our SFT approach could not accurately explain the large variation in abundance changes over time. We thus recommend to be cautious when using SFT substitution to infer species responses to temporal changes.</p

Forest microclimate dynamics drive plant responses to warming

Climate warming is causing a shift in biological communities in favor of warm-affinity species (i.e., thermophilization). Species responses often lag behind climate warming, but the reasons for such lags remain largely unknown. Here, we analyzed multidecadal understory microclimate dynamics in European forests and show that thermophilization and the climatic lag in forest plant communities are primarily controlled by microclimate. Increasing tree canopy cover reduces warming rates inside forests, but loss of canopy cover leads to increased local heat that exacerbates the disequilibrium between community responses and climate change. Reciprocal effects between plants and microclimates are key to understanding the response of forest biodiversity and functioning to climate and land-use changes

Replacements of small- by large-ranged species scale up to diversity loss in Europe’s temperate forest biome

The loss of biodiversity at the global scale has been difficult to reconcile with observations of no net loss at local scales. Vegetation surveys across European temperate forests show that this may be explained by the replacement of small-ranged species with large-ranged ones, driven by nitrogen deposition. Biodiversity time series reveal global losses and accelerated redistributions of species, but no net loss in local species richness. To better understand how these patterns are linked, we quantify how individual species trajectories scale up to diversity changes using data from 68 vegetation resurvey studies of seminatural forests in Europe. Herb-layer species with small geographic ranges are being replaced by more widely distributed species, and our results suggest that this is due less to species abundances than to species nitrogen niches. Nitrogen deposition accelerates the extinctions of small-ranged, nitrogen-efficient plants and colonization by broadly distributed, nitrogen-demanding plants (including non-natives). Despite no net change in species richness at the spatial scale of a study site, the losses of small-ranged species reduce biome-scale (gamma) diversity. These results provide one mechanism to explain the directional replacement of small-ranged species within sites and thus explain patterns of biodiversity change across spatial scales

Observer and relocation errors matter in resurveys of historical vegetation plots

Aim: Revisits of non-permanent, relocatable plots first surveyed several decades ago offer a direct way to observe vegetation change and form a unique and increasingly used source of information for global change research. Despite the important insights that can be obtained from resurveying these quasi-permanent vegetation plots, their use is prone to both observer and relocation errors. Studying the combined effects of both error types is important since they will play out together in practice and it is yet unknown to what extent observed vegetation changes are influenced by these errors. Methods: We designed a study that mimicked all steps in a resurvey study and that allowed determination of the magnitude of observer errors only vs the joint observer and relocation errors. Communities of vascular plants growing in the understorey of temperate forests were selected as study system. Ten regions in Europe were covered to explore generality across contexts and 50 observers were involved, which deliberately differed in their experience in making vegetation records. Results: The mean geographic distance between plots in the observer+relocation error data set was 24m. The mean relative difference in species richness in the observer error and the observer+relocation data set was 15% and 21%, respectively. The mean pseudo-turnover between the five records at a quasi-permanent plot location was on average 0.21 and 0.35 for the observer error and observer+relocation error data sets, respectively. More detailed analyses of the compositional variation showed that the nestedness and turnover components were of equal importance in the observer data set, whereas turnover was much more important than nestedness in the observer+relocation data set. Interestingly, the differences between the observer and the observer+relocation data sets largely disappeared when looking at temporal change: both the changes in species richness and species composition over time were very similar in these data sets. Conclusions: Our results demonstrate that observer and relocation errors are non-negligible when resurveying quasi-permanent plots. A careful interpretation of the results of resurvey studies is warranted, especially when changes are assessed based on a low number of plots. We conclude by listing measures that should be taken to maximally increase the precision and the strength of the inferences drawn from vegetation resurveys