Martin Magnes

Semi-Dry Grassland Restoration in the Se Alpine Foreland of Austria – A Study of Early Spontaneous Colonisation Patterns

Abstract We investigated early spontaneous colonisation patterns during semi-dry grassland restoration at two sites in SE Austria. The sites were left to regenerate passively without addition of plant propagules on a former arable field and an apple orchard. The sites were prepared only by ploughing (arable field) or clear cutting (apple orchard) and subsequently mowed annually. We studied whether, four years after project initiation, target species from adjacent semi-dry grasslands had established at the restored sites. We asked: 1) Does passive restoration lead to the establishment of target species? 2) Do abiotic parameters or distance to reference sites explain early colonisation patterns? 3) Do plant traits predict the colonisation success of different species? At each site, we collected data in 4 m × 4 m plots, in which we sampled the vegetation, analysed abiotic parameters (soil potassium- and phosphorus-content, soil-pH, slope) and recorded the minimum distance to the reference site. We tested for correlations between abiotic variables, plant traits and colonisation success. Colonisation patterns were not driven by abiotic soil conditions but rather by nearest distance to the reference sites. In addition, the vegetation developed differently in the former arable field and the apple orchard. Competitive species of the Arrhenatherion and thermophilic ruderal associations dominated the early restoration stage at both sites. Passive restoration of semi-dry grasslands on former agricultural land is unlikely to succeed unless complemented by initial ploughing, nutrient stripping and addition of propagules of rare species. Izvleček Preučevali smo vzorce zgodnje naselitve vrst med obnovo polsuhih travišč na dveh lokacijah v jugovzhodni Avstriji. Travišča smo prepustili pasivni obnovi brez vnosa propagul na nekdanjo obdelano površino in sadovnjak jablan. Obe površini smo predhodno obdelali tako, da smo polje preorali, sadovnjak pa posekali in nato kosili vsako leto. Po štirih letih od začetka projekta smo spremljali, ali se na obnovljenih površinah pojavljajo tarčne vrste s sosednjih polsuhih travišč. Zanimalo nas je: 1) Ali pasivna obnova omogoča naselitev tarčnih vrst? 2) Ali lahko z abiotskimi dejavniki ali oddaljenostjo ciljnega travišča razložimo vzorce zgodnje naselitve? 3) Ali lahko z rastlinskimi znaki napovemo uspešnost naselitve različnih vrst? Na vsaki lokaciji smo postavili poskusne ploskve 4 m × 4 m, kjer smo vzorčili vegetacijo, abiotske dejavnike (vsebost kalija in fosforja v tleh, pH tal, naklon) in izmerili minimalno oddaljenost od ciljnega travišča. Testirali smo korelacijo med abiotskimi dejavniki, rastlinskimi znaki in uspešnostjo naselitve vrst. Vzorci kolonizacije so bolj odvisni od bližine ciljnega travišča kot pa od abiotskih dejavnikov tal, poleg tega se je vegetacija razvijala drugače na nekdanji njivi kot v sadovnjaku. Na obeh rastiščih so v zgodnjih fazah obnove prevladovale konkurenčno uspešnejše vrste zveze Arrhenatherion in termofilnih ruderalnih združb. Pasivna obnova polsuhih travišč na nekdanjih obdelovanih površinah bo verjetno neuspešna brez predhodnega oranja, odstranjevanja hranil in dodajanja propagul redkih vrst

Can Naturalness Indicator Values Reveal Habitat Degradation? A Test of Four Methodological Approaches

ABSTRACT Assessing habitat naturalness belongs to the most current issues in conservation biology. It has been recognized that plants are able to indicate the naturalness of their habitat. Thus, species may be given relative naturalness indicator values (i.e. scores on an ordinal scale), reflecting their different tolerances against habitat degradation. In the present study, our first goal was to test whether relative naturalness indicator values are able to reveal known differences in naturalness levels. Our second purpose was to compare four different methodological approaches in order to identify which is the most reliable when analyzing habitat naturalness. We compared near-natural and degraded plots on the bases of (1) unweighted plot means, (2) plot medians, (3) unweighted naturalness indicator value populations, and (4) frequency-weighted naturalness indicator value populations. We found that relative naturalness indicator values performed well in differentiating among near-natural and degraded vegetation. Unweighted mean indicator values were the most reliable, but frequency-weighted indicator value populations were nearly as efficient as unweighted means. We conclude that relative naturalness indicator values provide a simple but reliable tool for estimating habitat deterioration.

A test of naturalness indicator values to evaluate success in grassland restoration

How should the somewhat vague term of restoration success be measured? This is a critical question rooted in European law, where in fact the creation of proper replacement habitats is a prerequisite for permitting projects that trigger a loss of species or habitats. Previous studies have used indices that relied on a comparison to reference sites, for example the number of a predefined pool of target species or compositional similarity. However, since restoration sites have rarely the same biotic and abiotic conditions as reference sites, plant communities in restored sites will not perfectly match the reference sites. Furthermore, such indices fail when reference sites are lacking or degraded. Hence, there is a need for an alternative approach that evaluates the conservation value of a restored site independently from reference sites. We propose that naturalness indicator values can be an option to measure restoration success. The approach of using naturalness indicator values makes use of the fact that plants are able to indicate environmental parameters, including degradation and regeneration. We compared and measured the restoration success of three well-established methods for grassland restoration (sod transplantation, hay transfer, seeding) with three commonly used indices (diversity, number of target species, similarity to reference sites). The results verified earlier studies and showed that sod transplantation led to the highest restoration success followed by hay transfer and seeding of sitespecific seed mixtures. Further, we used those well-established indices for an evaluation of novel, naturalness-based indices (unweighted and cover-weighted mean naturalness indicator values, the sum of naturalness indicator values). While calculating the means of naturalness indicator values failed to offer conclusive information on restoration success, we could show that the sum of naturalness indicator values was highly correlated with the number of target species and compositional similarity to reference sites. Thus, our case study demonstrated that naturalness indices can be an excellent option to estimate success in grassland restoration.

Biotope mapping of extensive/intensive grassland supported by Remote Sensing and Mobile GIS in Eastern Styria (Austria)

Abstract Sulzer W., Gspurning J., Magnes M., Pink R., Muick M., Sengl P.: Biotope mapping of extensive/ intensive grassland supported by remote sensing and mobile GIS in Eastern Styria (Austria). Ekológia (Bratislava), Vol. 32, No. 4, p. 335-344, 2013. The paper presents a case study for the application of remote sensing data (ASTER, LAND SAT and RG B orthophotographs) and GIS and methods in the context of biotope/grassland mapping/ monitoring in the Province of Styria (Austria). The range of the applied case study covers the detection of extensive/intensive grassland by techniques of multi-temporal satellite and airborne classification for grassland detection. The methodologies of three topics are discussed in this paper: special intensive used grassland detection, the preparation of a field map, with pre-processed land use polygons, and the description of a conceptual approach for a mobile client/server GIS grassland management and monitoring support system. Although from the legal (Government of Styria) point of view these methodologies cannot be used for the specific biotope mapping purposes, the verified results are showing valuable additional information for the intensive mapping activity during the fieldwork and postprocessing.

The influence of forest/grassland proportion on the species composition, diversity and natural values of an eastern Austrian forest-steppe

Eastern Austrian forest-steppe remnants are extremey important both from conservation and a scientific perspective, yet case studies integrating the examination of the grassland and the forest components are relatively scarce. Consequently, the knowledge on how the pattern of forested vs. non-forested patches influences species composition and diversity remains rather limited. In this study, we compared three sites with different forest/grassland proportions: grassland with a low canopy cover, a mosaic area with alternating forest and grassland habitats, and a forest with some canopy gaps. Our aim was to find out which one of them is the best for conservation purposes. We found that the grassland and the mosaic area had a similar composition, while the forested one was distinct from them. The mosaic vegetation seemed to be the most species rich, also hosting a high number of red-listed species. Beside forest-related and grassland-related species, the mosaic plot also supported some edge-related plants. We conclude that the preservation of mosaic-like forest- grassland habitats is the most favorable for conservation aims. Nevertheless, several species, among them some red-listed ones, were clearly linked either to the forest or to the grassland plot. Therefore, even though mosaics deserve a special attention, open grasslands and xeric forests should also be preserved.

The effects of different canopy covers on the herb layer in the forest-steppes of the Grazer Bergland (Eastern Alps, Austria)

The submontane belt of the eastern Alps is dominated by beech forests. However, on rocky and steep south-facing slopes, small vegetation mosaics have developed, which, to a certain degree, are similar to the Pannonian forest-steppes. In spite of their unique conservation importance and threatened status, they have received relatively little scientific attention. In this study we analyzed the spatial pattern of such mosaics. More specifically, our objective was to find out how canopy cover value influences the species composition of the herb layer. According to our results, canopy cover of Pinus sylvestris has a rather limited effect on the herb layer composition and species richness. Thus, in the studied canopy cover range (ca. 5–75% canopy cover), most species occurred under all canopy cover grades. This is presumably a result of the canopy characteristics and branching pattern of P. sylvestris: it can be assumed that the physical conditions of the canopy and intercanopy patches are somewhat similar. This is in sharp contrast with the Pannonian forest-steppes dominated by Quercus pubescens. We conclude that, even though the cessation of traditional land-use may not result in a rapid change of the composition in eastern Austrian forest-steppes, every effort must be made to conserve these valuable habitats.