Institut für Landschafts- und Pflanzenökologie

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Ableitung von Restitutionspotenzialen als Entscheidungshilfe bei der Umsetzung von Moorschutzprogrammen
(2005) Röhl, Markus; Böcker, Reinhard
As one of the last peatland-rich states of Germany, Baden-Württemberg possesses no self-standing, conservation program to protect its peatlands. Therefore, after consideration of the state administration, a strategy should be created in the next few years for a Baden-Württemberg peatland protection concept. With this in mind, a methodology for the derivation of peatland restitution potential was developed that can direct the future implementation of such a strategy. The exemplary methodology was developed for the nature conservation area ?Schwenninger Moos?, a medium sized former raised bog strongly disturbed by peat digging and agricultural amelioration. The results were applied to the entire surrounding bio-geographical region, the Baar and the Baaralb. Through this verification of the methodology, significant shortfalls in the state-wide dataset could become evident. As the basis of the evaluation of the restitution potential, data concerning the water level, trophy, and species and biotypes in Schwenninger Moos were collected. The water level of Schwenninger Moos was documented through 34 water gauges, the data from which was analysed through various methods. The half-year median and the combined examination of amplitude, average, and minimum values proved especially suitable for the characterisation of the sites. The trophic classifications of the sites were compared through measuring the principal nutrient levels, pH and conductivity values, as well as the C/N ratio. The vegetation of the investigation area was mapped and the results were subsequently compared to the mapping of biotypes of Baden-Württemberg, the mapping performed in the frame of Natura 2000, as well as that of indicator species groups. The mapping of indicator-species groups proved particularly suitable for the appraisal of the current status of a moor complex. The available data on the mires from the peatland register of Baden-Württemberg were somewhat old (40 years). Therefore these data were verified through comparison-boring and continued measurement by means of georadar. Significant differences arose in a number of comparisons between the peatland register and the author?s investigations with respect to the positional accuracy and the stratum sequence. The derivation of the restitution potential was carried out through the combination of three separate assessments: rewetting-possibility, biotic potential, and conversion potential. These three factors were derived through verbal-argument and brought together in a simple, five-step classification. The rewetting-possibility of an area is the main factor determining the restitution, and it depends considerably on drainage systems, topography, condition of the peat, and the water level. The biotic potential consists of the presence of peat-producing plants and the effects of rewetting on populations of endangered species. The conversion potential is essentially dependent on the dominant uses, ownership and social framework. The methodology was applied to altogether 34 peatland complexes of the Baar and Baaralb. The identification of these locations was only possible by a laborious combination of the peatland register, pedological cartography and conservation-oriented publications. It was found that the peatland register exhibited substantial deficits regarding the classification of small and shallow-layered locations in the Baar. Data concerning vegetation and the occurrence of animals and plants were available for the derivation of the restitution potential. However, some of these proved too old and/or too inaccurate or not spatially verified. Little to no data were present as to the water balance and drainage systems. Only three of the 34 locations exhibited a high restitution potential. 23,5% were classified as having moderate restitution potential; most of these sites are already under protection as nature conservation sites. A slight restitution potential was present in a total of 38.2% of the mire complexes, which consist mostly of small-scale spring mires and intensively agriculturally and silviculturally used locations. Likewise, 29.4% of the moorlands exhibited no more restitution potential. For the implementation of a state-wide mire protection program in the context of the investigation, the substantial deficits were pointed out and recommendations for action were formulated. Primarily, an updated and complete peatland register must be available. Furthermore, vegetation and endangered species maps of the entire peatland complexes protected as high conservation value areas should be available. It is in this regard that a system of indicator vegetation units of south German mires is to be aimed for, as is employed in northeast Germany, for example. Lists of priority sites should be made by regional teams of experts for the respective moor regions or administrative districts.
Automatic classification of submerged macrophytes at Lake Constance using laser bathymetry point clouds
(2024) Wagner, Nike; Franke, Gunnar; Schmieder, Klaus; Mandlburger, Gottfried; Wagner, Nike; Department of Geodesy and Geoinformation, TU Wien, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria;; Franke, Gunnar; Institute of Landscape and Plant Ecology (320), University of Hohenheim, Ottilie-Zeller-Weg 2, 70599 Stuttgart, Germany; (G.F.); (K.S.); Schmieder, Klaus; Institute of Landscape and Plant Ecology (320), University of Hohenheim, Ottilie-Zeller-Weg 2, 70599 Stuttgart, Germany; (G.F.); (K.S.); Mandlburger, Gottfried; Department of Geodesy and Geoinformation, TU Wien, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria;; Stateczny, Andrzej
Submerged aquatic vegetation, also referred to as submerged macrophytes, provides important habitats and serves as a significant ecological indicator for assessing the condition of water bodies and for gaining insights into the impacts of climate change. In this study, we introduce a novel approach for the classification of submerged vegetation captured with bathymetric LiDAR (Light Detection And Ranging) as a basis for monitoring their state and change, and we validated the results against established monitoring techniques. Employing full-waveform airborne laser scanning, which is routinely used for topographic mapping and forestry applications on dry land, we extended its application to the detection of underwater vegetation in Lake Constance. The primary focus of this research lies in the automatic classification of bathymetric 3D LiDAR point clouds using a decision-based approach, distinguishing the three vegetation classes, (i) Low Vegetation, (ii) High Vegetation, and (iii) Vegetation Canopy, based on their height and other properties like local point density. The results reveal detailed 3D representations of submerged vegetation, enabling the identification of vegetation structures and the inference of vegetation types with reference to pre-existing knowledge. While the results within the training areas demonstrate high precision and alignment with the comparison data, the findings in independent test areas exhibit certain deficiencies that are likely addressable through corrective measures in the future.
Biomonitoring von Fluorwasserstoff : neue Ansätze zum Einsatz Höherer Pflanzen als Akkumulationsindikatoren
(2009) Blanckart, Peter; Fangmeier, Andreas
The standardised grass culture as described in VDI guideline 3957 sheet 2 has successfully been used for years to identify pollution related effects and to assess pollution load with hydrogen fluoride. At the moment, two directives are in preparation for the evaluation of the results from the exposure of standardised grass cultures which provide scales for judging and values for orientation on the basis of detailed studies. The directives will be published as VDI 3857 sheet 1 and sheet 2 as green print in 2009. The directive VDI 2310 sheet 3 is being revised as well. Its publication (green print) is also expected for 2009. According to no. 5.3 of the directive VDI 3957 sheet 2, samples with less than 2 g of dry substance have to be rejected. However, the rejection of these samples leads to a time gap for assessing of 14 days or even of 4 weeks. In this context it should be tested how the accumulation of fluoride after exposure with air containing hydrogen fluoride would be affected at lower growth rates. It should also be tested if samples of exposed grass with a minimum weight of less than the required 2 g of dry substance can be used for determining the pollution situation. To evaluate these problems, exposures were performed with standardised grass cultures and with modified methodology in an area ? the city of Ransbach-Baumbach ? which is highly contaminated by fluorides. Parallel to bioindication, the fluoride concentration in the air was assessed with radial symmetric passive samplers as a physicochemical method. By this means a direct comparison of the concentration of air pollutants with the pollutant concentration in the grass could be performed. The tests confirmed that the study area is indeed quite contaminated with fluoride from anthropogenic sources. The area around Ransbach-Baumbach can be considered as a hot-spot for higher fluoride concentrations within Germany. The results confirm that fluoride pollution in Central Europe is still an ongoing problem, even though the pollution is mostly scattered and small scale limited. Therefore, evaluation fundamentals for bioindication methods for fluoride (passive and active) should be worked out for the future, although fluoride accumulations are no longer regularly determined in large scale bioindication monitoring networks. The application of Deschampsia flexuosa (L.) Trin. as an accumulation indicator as a possible alternative to Lolium multiflorum Lam. could not be confirmed in this study; the deviations of fluoride concentrations in Deschampsia flexuosa (L.) Trin. and in Lolium multiflorum Lam. were too large in the spatiotemporal comparison. The measurements performed with radialsymmetric passive samplers did not show a good relationship between the hydrogen fluoride concentration in the air and the fluoride concentration F- [µg g-1 ds] in the Lolium grass cultures. There were only very low correlations between the fluoride concentration and the increase of biomass as raw and dry weight of Lolium multiflorum Lam. (R2 of 0.0258 and 0.0099 at two measurement stations, respectively). Since conventionally an R2 of ≥ 0,6 is required to indicate significant relationships in ecological/ecotoxicological field studies, no link between the increase of biomass and fluoride concentration for the accumulation indicator Lolium multiflorum Lam. is concluded. Therefore, it is recommended to revise the VDI guideline 3957 sheet 2 so that standardised grass culture samples of less than 2 g dry substance are also accounted for in the determination of the accumulation of air pollutants like fluoride in plants.
Bird and insect pollinators differ in specialization and potential pollination services along disturbance and resource gradients
(2023) Neu, Alexander; Cooksley, Huw; Esler, Karen J.; Pauw, Anton; Roets, Francois; Schurr, Frank M.; Schleuning, Matthias
Combined studies of the communities and interaction networks of bird and insect pollinators are rare, especially along environmental gradients. Here, we determined how disturbance by fire and variation in sugar resources shape pollinator communities and interactions between plants and their pollinating insects and birds. We recorded insect and bird visits to 21 Protea species across 21 study sites and for 2 years in Fynbos ecosystems in the Western Cape, South Africa. We recorded morphological traits of all pollinator species (41 insect and nine bird species). For each site, we obtained estimates of the time since the last fire (range: 2–25 calendar years) and the Protea nectar sugar amount per hectare (range: 74–62 000 g/ha). We tested how post‐fire age and sugar amount influence the total interaction frequency, species richness and functional diversity of pollinator communities, as well as pollinator specialization (the effective number of plant partners) and potential pollination services (pollination service index) of insects and birds. We found little variation in the total interaction frequency, species richness and functional diversity of insect and bird pollinator communities, but insect species richness increased with post‐fire age. Pollinator specialization and potential pollination services of insects and birds varied differently along the environmental gradients. Bird pollinators visited fewer Protea species at sites with high sugar amount, while there was no such trend for insects. Potential pollination services of insect pollinators to Protea species decreased with increasing post‐fire age and resource amounts, whereas potential pollination services of birds remained constant along the environmental gradients. Despite little changes in pollinator communities, our analyses reveal that insect and bird pollinators differ in their specialization on Protea species and show distinct responses to disturbance and resource gradients. Our comparative study of bird and insect pollinators demonstrates that birds may be able to provide more stable pollination services than insects.
Development of assessment tools for Lake Sevan (Armenia) by the application of remote sensing data and geographic information systems (GIS) techniques
(2011) Agyemang, Thomas Kwaku; Schmieder, Klaus
Lake Sevan is the biggest source of water in Armenia. Its littoral zone, in addition to being a food source and a substrate for macrophytes, algae and invertebrates, provide refuge and spawning habitats for both young & old organisms especially fishes. Between 1933 and 1960s, the lake level had been lowered by 20 m below the original level by increasing the lake outflow intermittently for irrigation and electricity generation. This evidently had ecological and economical consequences on the lake ecosystem. The importance of assessing the accuracy of spatial data classifications derived from remote sensing methods and used in geographic information system (GIS) analyses has been regarded as a critical component of many projects. In this project, supervised classified QuickBird satellite imageries of both submersed macrophytes and landcover types (emersed vegetation) of the Gavaraget, Tsovazard and Masrik Regions of the study area were validated in a GIS environment. The results of these assessments were represented by error matrices presenting the overall accuracy, the user and producer accuracies in each category, as well as the kappa coefficients. For submersed macrophytes at the vegetation level, the overall accuracy ranging between 77-88% was achieved in all the investigation years. Alga blooms in the different years impacted on the accuracy of the classification. However, even through severe algal blooms user accuracies between 55% and 95% were achieved. On the other hand, at the growth type level, the overall accuracy was as high as over 70% and as low as below 49%. For emersed vegetation types, predominantly high overall accuracies of more than 70% were obtained in 2 of the investigation years. Above all, in 2008, only slight overall accuracy could be obtained. For reeds areas, high user accuracies of more than 78% could be obtained, while for shrubs, trees, no vegetation and grasses in the different years, very different classification accuracies were attained. Two habitat suitability models (one for fishes and one for birds) were built in a GIS environment in this project. While the Crucian Carp (Carassius auratus Gibelio Bloch) was chosen as lead species for the fish habitat, the Common Coot (Fulica atra) and the Great Crested Grebe (Podiceps cristatus) were chosen for the bird habitat models based on expert knowledge on Lake Sevan. Five fish habitat suitability classes were assigned in the model. There was a similar trend in the fish habitat areas in all the landscapes in Gavaraget, Tsovazard and Masrik regions. The habitat areas increased in 2007 and decreased in 2008. The increases in all the regions were the same (around 43%) while the highest reduction occurred in Gavaraget (47%) followed by Masrik (38%) and Tsovazard (25%) respectively. Apart from the reductions in habitat areas in 2008, there were severe decreases in the quality of the habitat areas in all the regions of interests. The increases and decreases were as a result of interannual fluctuations due to water level fluctuations and algal blooms of Lake Sevan. Also, for the bird habitat model, five classes were assigned. Tsovazard and Masrik had a similar trend in habitat areas with an initial increase in 2007 followed by a decrease in 2008. However, Gavaraget had reductions in 2007 and 2008. Again, in addition to the severe reductions in the habitat areas in 2008, there were severe decreases in the quality of the habitat areas in all the regions of interests. The changes in emersed macrophyte vegetations and the lake water level fluctuations effected the different changes in the bird habitat areas.
Evaluation der Richtlinienkonformität von Verträglichkeitsprüfungen nach Artikel 6 Flora-Fauna-Habitat-Richtlinie in der Planungspraxis
(2011) Matthäus, Gunther; Dieterich, Martin
The dissertation presents findings of a study on the practical implementation of the Habitats Direktive, Art. 6 (3). The formal und methodological quality of 50 appropriate assessments according to the Habitats-Direktive was analysed. Overall, a solid or even high to very high level of quality was found. Only few assessments exhibited serious shortcomings or mistakes with relevant effects on the finding of the assessments. These shortcomings coud be avoided by the introdiktion of binding quality standards.
Floral visitation to alien plants is non‐linearly related to their phylogenetic and floral similarity to native plants
(2022) Razanajatovo, Mialy; Rakoto Joseph, Felana; Rajaonarivelo Andrianina, Princy; van Kleunen, Mark
Biological invasions are key to understanding ecological processes that determine the formation of novel interactions. Alien species can negatively impact floral visitation to native species, but native species may also facilitate early establishment of closely related alien species by providing a preadapted pollinator community. We tested whether floral visitation to alien species depended on phylogenetic relatedness and floral similarity to native species. In a field experiment, we simulated the early stages of an invasion by adding potted alien plants into co‐flowering native communities. We paired each alien plant with a host native plant, and recorded floral visitation to them for 3,068 hr (totalling 84,814 visits). We used 34 alien and 20 native species in 151 species combinations. We tested whether the number of floral visits to alien plants, the proportion of visits to alien plant relative to visits to both alien and native plants, and the similarity in flower visitor compositions of alien and native plants depended on phylogenetic and floral trait distances between alien and native species. Floral visitation to alien species was highest when they had intermediate floral trait distances to native species, and either low or high phylogenetic distances. Alien species received more similar flower‐visitor groups to natives when they had low phylogenetic and either low or high floral trait distances to native species. Co‐flowering native species may facilitate floral visitation to closely related alien species, and distantly related alien plants seem to avoid competition for flower visitors with native plants. Alien species with similar floral traits to natives compete with them for flower visitors, and alien species with dissimilar floral traits may not share flower visitors with native species. Alien species with intermediate floral trait distances to natives are most likely to receive flower visitors, as they are not too dissimilar and may still share flower visitors with native species, but not too similar to compete for flower visitors with them. The non‐linear patterns between floral visitation and similarity of the alien and native species suggest that an interplay of facilitation and competition simultaneously drives the formation of novel plant‐pollinator interactions.
Increases in functional diversity of mountain plant communities is mainly driven by species turnover under climate change
(2023) Schuchardt, Max A.; Berauer, Bernd J.; Duc, Anh Le; Ingrisch, Johannes; Niu, Yujie; Bahn, Michael; Jentsch, Anke
Warming in mountain regions is projected to be three times faster than the global average. Pronounced climate change will likely lead to species reshuffling in mountain plant communities and consequently change ecosystem resilience and functioning. Yet, little is known about the role of inter‐ versus intraspecific changes of plant traits and their consequences for functional richness and evenness of mountain plant communities under climate change. We performed a downslope translocation experiment of intact plant‐soil mesocosms from an alpine pasture and a subalpine grassland in the Swiss and Austrian Alps to simulate an abrupt shift in climate and removal of dispersal barriers. Translocated plant communities experienced warmer and dryer climatic conditions. We found a considerable shift from resource conservative to resource acquisitive leaf‐economy in the two climate change scenarios. However, shifts in leaf‐economy were mainly attributable to species turnover, namely colonization by novel lowland species with trait expressions for a wider range of resource use. We also found an increase in vegetative height of the warmed and drought‐affected alpine plant community, while trait plasticity to warming and drought was limited to few graminoid species of the subalpine plant community. Our results highlight the contrast between the strong competitive potential of novel lowland species in quickly occupying available niche space and native species' lack of both the intraspecific trait variability and the plant functional trait expressions needed to increase functional richness under warming and drought. This is particularly important for the trailing range of many mountain species (i.e. subalpine zone) where upward moving lowland species are becoming more abundant and abiotic climate stressors are likely to become more frequent in the near future. Our study emphasizes mountain plant communities' vulnerability to novel climates and biotic interactions under climate change and highlights graminoid species as potential winners of a warmer and dryer future. Keywords: alpine grassland, functional diversity, invasion, species turnover, traitspace, translocation
Interactions between protea plants and their animal mutualists and antagonists are structured more by energetic than morphological trait matching
(2022) Neu, Alexander; Cooksley, Huw; Esler, Karen J.; Pauw, Anton; Roets, Francois; Schurr, Frank M.; Schleuning, Matthias
Traits mediate mutualistic and antagonistic interactions between plants and animals, and should thus be useful for predicting trophic species interactions. Studies to date have examined the importance of morphological trait matching for plant–animal interactions, but have rarely explored the extent to which these interactions are shaped by matching between energetic provisions of plants and energetic demands of animals. We tested whether energetic and/or morphological trait matching shapes interactions between Protea plant species and their interacting animal mutualists and antagonists in the Cape Floristic Region, South Africa. We recorded interactions between 22 Protea species, pollinating insects and vertebrates as well as seed predators (endophagous insect larvae in protea cones) at 21 study sites. To relate species interactions to matching trait pairs, we measured key morphological traits (shape and size of flower heads and seed cones, and mouth part length as well as body length) and quantified the animals' energetic demands (metabolic rate) together with the plants' energetic provisions (nectar sugar amount, seed‐to‐cone mass ratio). We calculated log ratios of both energetic and morphological traits between animals and plants as predictor variables for the number of observed interactions between Protea species and their animal interaction partners. For both mutualistic and antagonistic interactions, we found significant effects of morphological and energetic trait ratios on the interactions between plants and animals. Trait ratios accounted for 11% to 22% of variation in species interactions. Consistent with energetic trait matching, we found a hump‐shaped relationship between interaction frequency and log ratios of energetic traits of animals and plants, indicating that interactions were most frequent at intermediate log ratios between energetic demand and provision. Effects of morphological trait ratios on interactions were statistically supported in most cases, but were variable in the magnitude and shape of the predicted relationships. Across animal taxa and interaction types, energetic traits had more consistent effects on interactions between plants and animals than morphological traits. This suggests that energy can function as an important interaction currency and facilitate the understanding and prediction of trophic species interactions.
Nitrogen dynamics of grassland soils with differing habitat quality: high temporal resolution captures the details
(2023) Kukowski, Sina; Ruser, Reiner; Piepho, Hans‐Peter; Gayler, Sebastian; Streck, Thilo
Excessive nitrogen (N) input is one of the major threats for species‐rich grasslands. The ongoing deterioration of habitat quality highlights the necessity to further investigate underlying N turnover processes. Our objectives were (1) to quantify gross and net rates of mineral N production (mineralization and nitrification) and consumption in seminatural grasslands in southwest Germany, with excellent or poor habitat quality, (2) to monitor the temporal variability of these processes, and (3) to investigate differences between calcareous and decalcified soils. In 2016 and 2017, gross N turnover rates were measured using the 15N pool dilution technique in situ on four Arrhenatherion meadows in biweekly cycles between May and November. Simultaneously, net rates of mineralization and nitrification, soil temperature, and moisture were measured. The vegetation was mapped, and basic soil properties were determined. The calcareous soils showed higher gross nitrification rates compared with gross mineralization. In contrast, nitrification was inhibited in the decalcified soils, most likely due to the low pH, and mineralization was the dominant process. Both mineralization and nitrification were characterized by high temporal variability (especially the former) and short residence times of N in the corresponding pools (<2 days) at all sites. This illustrates that high temporal resolution is necessary during the growing season to detect N mineralization patterns and capture variability. Parallel determination of net N turnover rates showed almost no variability, highlighting that net rates are not suitable for drawing conclusions about actual gross turnover rates. During the growing season, the data show no clear relationship between soil temperature/soil moisture and gross N turnover rates. For future experiments, recording of microbial biomass, dissolved organic matter, and root N uptake should be considered.

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