2013. december 18., szerda

Albert et al. (2014) Applied Vegetation Science

Ágnes-Júlia Albert, András Kelemen, Orsolya Valkó, Tamás Miglécz, Anikó Csecserits, Tamás Rédei, Balázs Deák, Béla Tóthmérész & Péter Török (2014): Secondary succession in sandy old-fields: a promising example of spontaneous grassland recovery. Applied Vegetation Science, DOI: 10.1111/avsc.12068, PDF itt

Question: Based on the spontaneous vegetation development of old-fields in the Nyírség and Kiskunság sand regions (Hungary), we aimed to answer the following questions using the chronosequencemethod: (1) how do the proportions of different functional groups change during succession; (2) which target species establish successfully in the old-fields during the course of succession; and (3) how successful is spontaneous succession in the recovery of target grasslands?
Location: Two sand regions of the Great Hungarian Plain: (1) the Nyírség sand region (East Hungary, acidic sand, moderately continental climate) and the Kiskunság (Central Hungary, calcareous sand, continental climate).
Methods: Altogether 24 old-fieldswere classified into young (<10-yr-old),middle-aged (10–20-yr-old) and late-succession (20–40-yr-old) old-fields; four fields in each age category. For baseline vegetation reference, three open and three closed sand grassland stands in both regions were sampled in the vicinity of the old-fields. The percentage cover of vascular plants was recorded in five 2 9 2-m plots in each field, in early May and late June 2012. We used life forms, clonal spreading traits and Ellenberg indicator values for nutrients in the analysis. Species of Festuco-Brometea class were considered as target species.
Results: The cover of hemicryptophytes and geophytes increased, the cover of short-lived species decreased with time. Cover of species without clonal spreading ability decreased, while cover of species with clonal spreading ability increased with increasing field age. The cover of invasive species decreased with increasing field age. The majority of target species had established already in the young and middle-aged old-fields, although their cover was significantly higher in the two older age groups.
Conclusion: Spontaneous succession can be a vital option in recovery of sand grassland vegetation in Central Europe; the majority of the species pool of sandy grasslands can be recovered in the first 10–20 yrs. However, the success of grassland recovery can be strongly influenced by the surrounding species pool and can be slowif seed dispersal is limited. Spontaneous succession ismost promising when the target species of grasslands immigrate at the very beginning of the succession, within the first few years.

abandonment, acidic sand, calcareous sand, clonal traits, grassland restoration, invasion, spontaneous succession

2013. december 16., hétfő

Király et al. (2013) Preslia

Rubus balatonicus Borbás, belonging to ser. Micantes Sudre and a long-neglected apomictic species occurring in Hungary, is herein re-evaluated. This species is a nemophilous bramble occurring in the Transdanubian Mts (central Hungary) and has distinctive morphological features that clearly differ from those of related species. A list of localities and a distribution map are presented in addition to the designation of a lectotype and the description and first complete illustration of this species. As part of a general revision of Rubus ser. Micantes occurring in Hungary, the characteristics, distribution and ecology of three additional species (R. clusii Borbás, R. styriacus Halácsy and R. tabanimontanus Figert) of this series reported from Hungary are also assessed.

biogeography, distribution, ecology, Hungary, Rubus, ser. Micantes, taxonomy

Király et al. (2013) Biologia

A remarkable population of Carex extensa (Cyperaceae) was found south of Lake Fertő (Neusiedler See) in Hungary in 2012. This species typically occurs in coastal salt marshes in Europe and was hitherto unknown from the Pannonian Basin. The locality is situated in a territory which has been embanked in 1911. Keeping also in mind that the vegetation developed here from reed beds to saline habitats, we conclude that C. extensa reached the salt marshes of the area through long distance dispersal by water birds from the European coast in the last century. Nevertheless, several other maritime littoral species grow in the region, and the possibility that there is a hidden population of C. extensa at another site(s) nearby cannot be excluded. Lake Fertő is often described as the “westernmost steppe lake” and supports one of the richest European inland littoral floras. Although it appears likely that C. extensa has only recently colonised the site, we consider this discovery to be of significant biogeographical importance.

Juncion maritimi, biogeography, drainage, landscape history, long distance dispersal, salt marshes

2013. december 6., péntek

Biró et al. (2013) Community Ecology

M. Biró, K. Szitár, F. Horváth, I. Bagi, Zs. Molnár (2013): Detection of long-term landscape changes and trajectories in a Pannonian sand region: comparing land-cover and habitat-based approaches at two spatial scales. Community Ecology 14(2): 219-230. DOI: 10.1556/ComEc.14.2013.2.12

A key driver of biodiversity loss is human landscape transformation. Change detection and trajectory analysis are frequently applied methods for studying landscape change. We studied to what degree habitat-specific change detection and trajectory analysis provide different information on landscape change compared to the analysis with land-cover statistics. Our research was carried out at two spatial scales (regional, 1800 km2, 360 random points; local, 23 km2, polygon-based maps) in the Kiskunság, Hungary. Spatio-temporal databases were prepared using historical maps, aerial photos and satellite images from 1783, 1883, 1954, and 2009. Local expert knowledge of landscape history and recent vegetation was used during the historical reconstructions. We found large differences at both scales between land-cover based and habitat-specific analyses. Habitat-specific change detection revealed that grassland loss was not continuous in the different habitats, as land-cover based analysis implied. Ploughing affected open sand grasslands and sand steppes differently in the periods studied. It was only apparent from the habitat-specific analyses that from the grasslands only mesotrophic and Molinia meadows were relatively constant, up until the 1950s. The gradual increase in forest area revealed by land-cover CHD analyses was split into natural and anthropogenic processes by habitat-specific analyses. Habitat specific trajectory analysis also revealed ecologically important historical differences between habitats. Afforestation affected especially the open sand grasslands, whereas wetland habitats were relatively stable. The most important trajectory was the one in which closed sand steppes were ploughed during the 19th century, and remained arable fields until present. Fifty percent of the regional trajectories of 18th century open sand grasslands terminated in tree plantations at present, though 82% of the current open sand grasslands of the local site can be regarded as ancient. We concluded that dividing land-cover categories into finer habitat categories offered an opportunity for a more precise historical analysis of key habitats, and could reveal important ecological processes that cannot be reconstructed with land-cover based analyses. It also highlighted habitat-specific processes making natural and social drivers better interpretable. Information on the diversity of habitat-histories may serve as a basis for spatially more explicit conservation management.

Change detection analysis, Habitat change, Habitat continuity, Land-cover change, Regional scale

2013. december 4., szerda

Mücke et al. (2013) Canadian Journal of Remote Sensing

Mücke, W., Deák, B., Schroiff, A., Hollaus, M., Pfeifer N. (2013): Estimation of dead wood using small footprint airborne laser scanning data. Canadian Journal of Remote Sensing. DOI: 10.5589/m13-013
URL: http://pubs.casi.ca/doi/abs/10.5589/m13-013

Deadwood was identified as an important indicator for habitat condition and biodiversity in forests. The assessment of downed trees is therefore part of sustainable forest management and ecological monitoring. However, manual quantification of deadwood in forests is challenging, time consuming, and considered cost-inefficient. Full-waveform airborne laser scanning (FWF-ALS) can be used to support the assessment process. The amplitude and width of the backscattered pulses contain information on the properties of the surface. We used these observations for the identification of downed trees in a Natura2000 forest site. A high density FWF-ALS data set was acquired under leaf-off conditions. Echo width and type (i.e., first,intermediate, and last) information as well as normalized echo heights were used to filter the point cloud and derive a digital height model (DHM). This DHM depicts downed stems as line-like features. Image processing was applied to derive and refine regions representing fallen trees. Terrestrial reference data consisting of locations and dimensions of downed trees, as well as state of decay were used for evaluation. Direct identification of downed trees in FWF-ALS point clouds was possible (completeness 75%, correctness 90%), but it was influenced by factors such as dimension, state of decay, vegetation density, and penetration of the laser.

Valkó et al. (2013) Basic and Applied Ecology

Orsolya Valkó, Péter Török, Balázs Deák, Béla Tóthmérész (2013): Prospects and limitations of prescribed burning as a management tool in European grasslands. Basic and Applied Ecology, in press. http://dx.doi.org/10.1016/j.baae.2013.11.002

Grassland managers and scientists are increasingly interested in cost-effective alternative ways of grassland biodiversity conservation. Prescribed burning is a promising management tool which should be integrated in the planning of management efforts. In addition, small-scale prescribed burning is an effective fire suppression strategy to decrease the serious negative impacts of uncontrolled burnings on ecosystems and human life. Prescribed burning forms an integral part of the North-American grassland management practice, while in Europe it is rarely applied, despite the fact that uncontrolled burning occurs frequently in some regions. Our goal was to evaluate the use of prescribed burning as a promising but neglected management tool in European grasslands. We found that European studies on prescribed burning of grasslands are scarce and we conclude that annual burning is usually not an appropriate option for the conservation of species-rich grasslands. We reviewed burning studies from North-America to identify findings which might be adapted to the European grassland conservation strategy. In North-America, contrary to Europe, the application of burning is fine tuned in terms of frequency and timing, and usually combined with other restoration measures (grazing or seed sowing). Thus, we conclude that with the application of carefully designed prescribed burning, multiple conservation goals, e.g. invasion control and enhancing landscape-level heterogeneity, can be linked with an effective fire suppression strategy. We emphasize that for the application of prescribed burning in Europe, the general findings of carefully designed case studies should be combined with the practical knowledge of conservation managers concerning the local application circumstances to reach specific management objectives.

Biomass, Ecosystem services, Fire, Grazing, Mowing, Prairie

2013. december 1., vasárnap

Zlinszky et al. (2012) Remote Sensing

A. Zlinszky, W. Mücke, H. Lehner, C. Briese, N. Pfeifer (2012): Categorizing Wetland Vegetation by Airborne Laser Scanning on Lake Balaton and Kis-Balaton, Hungary". Remote Sensing, 4 (6): 1617-1650.

Outlining patches dominated by different plants in wetland vegetation provides information on species succession, microhabitat patterns, wetland health and ecosystem services. Aerial photogrammetry and hyperspectral imaging are the usual data acquisition methods but the application of airborne laser scanning (ALS) as a standalone tool also holds promises for this field since it can be used to quantify 3-dimensional vegetation structure. Lake Balaton is a large shallow lake in western Hungary with shore wetlands that have been in decline since the 1970s. In August 2010, an ALS survey of the shores of Lake Balaton was completed with 1 pt/m2 discrete echo recording. The resulting ALS dataset was processed to several output rasters describing vegetation and terrain properties, creating a sufficient number of independent variables for each raster cell to allow for basic
multivariate classification. An expert-generated decision tree algorithm was applied to outline wetland areas, and within these, patches dominated by Typha sp. Carex sp., and Phragmites australis. Reed health was mapped into four categories: healthy, stressed, ruderal and die-back. The output map was tested against a set of 775 geo-tagged ground photographs and had a user’s accuracy of >97% for detecting non-wetland features (trees, artificial surfaces and low density Scirpus stands), >72% for dominant genus detection and >80% for most reed health categories (with 62% for one category). Overall classification accuracy was 82.5%, Cohen’s Kappa 0.80, which is similar to some hyperspectral or multispectral-ALS fusion studies. Compared to hyperspectral imaging, the processing chain of ALS can be automated in a similar way but relies directly on differences in vegetation structure and actively sensed reflectance and is thus probably more robust. The data  acquisition parameters are similar to the national surveys of several European countries, suggesting that these existing datasets could be used for vegetation mapping and monitoring.

LIDAR, wetlands, Phragmites australis, Carex, Typha, ecosystem health, vegetation classification

Zlinszky & Tímár (2013) Hydrology and Earth System Sciences

Socio-hydrology is the science of human influence on hydrology and the influence of the water cycle on human social systems. This newly emerging discipline inherently involves a historic perspective, often focusing on time scales of several centuries. While data on human history is typically available for this time frame, gathering information on the hydrological situation during such a period can prove difficult: measured hydrological data for such long periods are rare, while models and secondary datasets from geomorphology, pedology or archaeology are typically not accurate enough over such a short time. In the first part of this study, the use of historic maps in hydrology is reviewed. Major breakthroughs were the acceptance of historic map content as valid data, the use of preserved features for investigating situations earlier than the map, and the onset of digital georeferencing and data integration. Historic maps can be primary quantitative sources of hydro-geomorphological information, they can provide a context for point-based measurements over larger areas, and they can deliver time series for a better understanding of change scenarios.
In the second part, a case study is presented: Water level fluctuations of Lake Balaton were reconstructed from maps, levelling logs and other documents. An 18th century map system of the whole 5700 km2 catchment was georeferenced, integrated with two 19th century map systems, and wetlands, forests and open water digitized. Changes in wetland area were compared with lake water level changes in a 220-year time series. Historic maps show that the water level of the lake was closer to present-day levels than expected, and that wetland loss pre-dates drainage of the lake.
The present and future role of historic maps is discussed. Historic hydrological data has to be treated with caution: while it is possible to learn form the past, the assumption that future changes will be like past changes does not always hold. Nevertheless, old maps are relatively accessible datasets and the knowledge base for using them is rapidly growing, and it can be expected that long-term time series will be established by integrating georeferenced map systems over large areas.
In the Appendix, a step-by-step guide to using historic maps in hydrology is given, starting from finding a map, through georeferencing and processing the map to publication of the results.

Mahon et al. (2013) Forest Ecology and Management

Mahon, C. L., Bayne, E. M., Sólymos, P., Matsuoka, S. M., Carlson, M., Dzus, E., Schmiegelow, F. K. A., Cumming, S. G., & Song, S. J. (2013): Does expected future landscape condition support proposed population objectives for boreal birds? Forest Ecology and Management, DOI: 10.1016/j.foreco.2013.10.025

Assessing the feasibility of proposed Bird Conservation Region (BCR) population objectives requires comparing expected future population size estimates to proposed population objectives. Linking statistical bird habitat models with landscape simulation models can provide a direct method for assessing the ecological and economic implications of alternative land and resource scenarios within a BCR or BCR sub-region. We demonstrate our approach for analyses of future habitat supply and population size for a suite of priority landbird species using the ALCES® landscape simulation model and empirical bird habitat models within a multi-use landscape located in northeast Alberta, Canada and BCR 6-Boreal Taiga Plans. We used ALCES® to simulate future landscape condition over a 100 year time period under three scenarios: business as usual, protected areas, and climate change. Shortfalls between simulated population size estimates at year 30 and proposed population objectives existed for each of the four priority bird species examined suggesting that expected future landscape condition will not support proposed population objectives for these species. Boreal species strongly associated with mature and old forest habitats exhibited population declines over the 100 year simulation period. One habitat generalist, a species associated with both early and late seral stages, appeared to benefit from the range of land use scenarios examined. Our approach improves upon current static approaches used to step down BCR scale population objectives to sub-regional scale habitat objectives by utilizing statistical bird population response models to estimate density and a dynamic landscape simulation model to estimate expected future habitat condition.

Bird Conservation Regions, Boreal forest, Landscape simulation model, Land use scenarios, Partners in Flight, Population objectives