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Soil seed banks have a high potential for vegetation re-establishment in restoration projects. We studied the soil seed bank in an oxbow system of a disconnected floodplain of the Danube River in Southern Germany. The aim of the study was to analyze if floodplain target species were still present in the seed bank after more than 150 years of embankment and disconnection from fluvial dynamics. In this context we investigated seed density, seed bank species richness and species composition in four broad habitat types with and without water-level fluctuations during the time of embankment (permanent water, fluctuating water, reed bed, hardwood floodplain forest). In addition, the similarity between seed bank and above-ground vegetation in these habitat types was studied in order to predict the success of future restoration measures. In total, 124 vascular plant species were determined in the seed bank samples. More than 50 % (66 species) were target species typical for floodplain habitats and 26 of these target species were lost or very rare in the above-ground vegetation. The four habitat types differed significantly in mean seed density and mean species richness. Mean species richness and the number of target species in the seed bank as well as the mean seed density were greatest in the habitats with fluctuating water level whereas mean seed density was much lower in the parts with more or less stable conditions like permanently standing water and hardwood floodplain forest. Sørensen similarity between seed bank and above-ground vegetation was very low in habitats with more or less stable water levels and desirable floodplain target species were very rare or completely absent. Our results indicate that the soil seed bank can be an important seed reservoir for the ecological restoration of floodplain plant communities especially for habitats with unstable environmental conditions during the period of disconnection. Restoration of water level dynamics is important to maintain the seed bank of populations of floodplain target species.
Despite the high significance of the Western Siberian grain belt for crop production in Russia, its weed communities are largely unknown. In this region spring wheat is grown on fertile Chernozem soils with large field sizes but land-use intensity per area is low compared to Central Europe. By usin a randomized sampling design we studied arable weed assemblages in the northern forest-steppe zone of Tyumen region on 99 within-field sampling plots of 100 m² size. Surprisingly, with average of 9.8 ± 3.8 species 100 m-2 species richness was low when compared with low-input farming in Central Europe and did not differ between areas of different land-use intensity. Against expectations species composition was not predominantly controlled by soil characteristics and climate, most likely due to short natural gradients. Instead, management factors such as fertilization and tillage intensity seemed to be important factors. Except for two species the Tyumen weed flora consisted mainly of species that are widespread throughout the temperate zone. We found only 10 species with an origin or core area in North Asia or Eastern Europe. The species pool was generally small and with 26% the proportion of non-native spe cies (archaeophytes) was low, when compared to Central European weed communities. Given that weed communities with higher species richness are described from neighboring Bashkiria, we conclude that arable land-use intensity in Tyumen region is high enough to reduce community species richness within arable fields estimated by a randomized sampling design. Since measured soil nutrient values did not affect species richness, herbicide use is most likely the crucial management factor. Furthermore, species-richness was vitally restricted by the small species pool. The low proportion of thermophilous arable weed species that originate from the Mediterranean or Middle-Eastern area and contribute signif icantly to the Central European weed diversity indicate that climatic dispersal limitations may be re sponsible for the small number of weed species in the Tyumen flora. An additional constraint was the short history of arable farming in Western Siberia, where considerable arable land use was started only by the end of the 17th century.
Are natural floods accelerators for streambank vegetationdevelopment in floodplain restoration?
(2021)
Riverbanks are very dynamic habitats for riparian vegetation strongly influenced byfluvial and geomorphic processes. This habitat type was severely reduced in the pastby river straightening and bank stabilisation. Restoration and establishment of newfloodplain streams promote this habitat, but a directed succession to later stages wasobserved many times. Our study aimed to analyse whether the often observeddirected succession of the streambank vegetation after restoration implementationcould be reversed by a natural flood along a newly created floodplain stream. Weinvestigated the effects of a natural flood in 2013 and different prerestorationconditions on species development in the riparian zone. Vegetation was studiedalong 12 transects in four different sections from 2011 to 2014. Species composi-tion differed strongly between the sections. Species richness was lowest in a newlydug steep section with high morphological dynamics and highest on wider flatstreambanks. Changes during the years reflecting different hydrological eventsvaried between sections. The high natural flood in 2013 reduced the cover of theherb layer and increased bare ground, which led in most sections to a loss of non-target species. Total target species richness did not change due to the natural flood,while target species showed a high turnover rate. In the following year, however,the flood‐induced development of species composition, in general, was reversed.Natural floods changed abiotic and biotic conditions along the streambank, but theydid not accelerate ecological restoration towards predefined target ecosystems.However, they were necessary to preserve the needed dynamic vegetation changesand species turnover to hinder the succession to later stages dominated by a fewspecies. Our study shows that riparian vegetation near the streambank can bemonitored most effectively in cross‐profile transects, both in the long‐term andevent‐related.
Aims
Understanding fine-grain diversity patterns across large spatial extents is fundamental for macroecological research and biodiversity conservation. Using the GrassPlot database, we provide benchmarks of fine-grain richness values of Palaearctic open habitats for vascular plants, bryophytes, lichens and complete vegetation (i.e., the sum of the former three groups).
Location
Palaearctic biogeographic realm.
Methods
We used 126,524 plots of eight standard grain sizes from the GrassPlot database: 0.0001, 0.001, 0.01, 0.1, 1, 10, 100 and 1,000 m2 and calculated the mean richness and standard deviations, as well as maximum, minimum, median, and first and third quartiles for each combination of grain size, taxonomic group, biome, region, vegetation type and phytosociological class.
Results
Patterns of plant diversity in vegetation types and biomes differ across grain sizes and taxonomic groups. Overall, secondary (mostly semi-natural) grasslands and natural grasslands are the richest vegetation type. The open-access file ”GrassPlot Diversity Benchmarks” and the web tool “GrassPlot Diversity Explorer” are now available online (https://edgg.org/databases/GrasslandDiversityExplorer) and provide more insights into species richness patterns in the Palaearctic open habitats.
Conclusions
The GrassPlot Diversity Benchmarks provide high-quality data on species richness in open habitat types across the Palaearctic. These benchmark data can be used in vegetation ecology, macroecology, biodiversity conservation and data quality checking. While the amount of data in the underlying GrassPlot database and their spatial coverage are smaller than in other extensive vegetation-plot databases, species recordings in GrassPlot are on average more complete, making it a valuable complementary data source in macroecology.
Semi-natural grasslands (SNGs) are an essential part of European cultural landscapes. They are an important habitat for many animal and plant species and offer a variety of ecological functions. Diverse plant communities have evolved over time depending on environmental and management factors in grasslands. These different plant communities offer multiple ecosystem services and also have an effect on the forage value of fodder for domestic livestock. However, with increasing intensification in agriculture and the loss of SNGs, the biodiversity of grasslands continues to decline. In this paper, we present a method to spatially classify plant communities in grasslands in order to identify and map plant communities and weed species that occur in a semi-natural meadow. For this, high-resolution multispectral remote sensing data were captured by an unmanned aerial vehicle (UAV) in regular intervals and classified by a convolutional neural network (CNN). As the study area, a heterogeneous semi-natural hay meadow with first- and second-growth vegetation was chosen. Botanical relevés of fixed plots were used as ground truth and independent test data. Accuracies up to 88% on these independent test data were achieved, showing the great potential of the usage of CNNs for plant community mapping in high-resolution UAV data for ecological and agricultural applications.
Ecological restoration of an urban demolition site through introduction of native forb species
(2020)
Urban brownfields can provide habitats for endangered native plant species but may also support invasive non native species. The aim of our study was to develop and test different measures for the ecological restoration of an urban brownfield. We aimed to enhance native plant species richness by seeding two native forb seed mix tures containing 25 (HD-mixture) and 13 species (LD-mixture), respectively, without affecting spontaneously colonizing plant species of nature conservation value. Additionally, we tested the effects of species introduction and mowing on the establishment of invasive non-native plant species, woody species development, and per ennial grass dominance.
With establishment rates of 84% (HD) and 92% (LD) in the first study year and about 60% for both seed mixtures in the fourth year, species introduction was successful and led to rapid re-vegetation of the formerly bare brownfield. Although seeding did not result in increased species richness using either seed mixture, the dominance of perennial grasses was significantly reduced by the establishment of forb species from the HD mixture. Overall, we observed the spontaneous establishment of ten plant species of conservation value; seeding affected these species only temporarily, in the second year. Seeding (with either seed mixture) and mowing both resulted in reduced cover of woody species and a lower frequency of the invasive non-native Robinia pseudoa cacia.
Our study demonstrated the high nature conservation value of dry and nutrient-poor urban brownfields for spontaneously occurring threatened plant species. Further studies have to evaluate if the reduced cover of grasses and woody species through introduction of site-specific native forb species might increase these sites’ aesthetic value and broader acceptance of brownfields by urban residents.
Establishment of calcareous grassland on ex-arable fields by introducing target species is one of the most frequently used methods to restore the species assemblages of this highly endangered habitat type. The present study evaluates the long-term success of calcareous grassland restoration on former arable land in the vicinity of one of the oldest nature reserves in Bavaria, the “Garchinger Heide”. The restoration experiment combined different measures like topsoil removal, transfer of freshly cut seed-containing hay and additional sowing to the following variants in a 21-year experiment: (1) No topsoil removal, no hay transfer (control), (2) no topsoil removal with immediate hay transfer, (3) topsoil removal with immediate hay transfer and (4) topsoil removal with hay transfer 10 years after the start of restoration. Eleven Red List species which had not been transferred successfully were additionally sown after 9 to 19 years. Due to a limited availability of seeds, sowing of these species was mainly restricted to areas with topsoil removal, where better establishment was expected due to low vegetation cover. Five rare species with abundant seed production were also sown to plots without topsoil removal and hay transfer. The nature reserve served both as the donor area of the target species and as the reference to evaluate restoration success. Regarding aboveground biomass and total vegetation cover, greatest similarity to the donor site was observed on plots without topsoil removal. In contrast, the highest numbers of target species occurred on plots with topsoil removal, hay transfer and additional sowing. Similarity in species composition between restoration sites and the reference area increased over time, but species composition of restored sites did not fully reflect the reference after 21 years. One reason for the remaining dissimilarity was probably that topsoil removal favored stress tolerant species which were less common on the mature and more fine-grained soils of the nature reserve. Plots without topsoil removal still differed from the reference by their high vegetation cover and a significantly higher proportion of mesophytic grassland species. The study also showed that 19 Red List species were successfully established on the former arable fields, eight of them presumably by sowing. Nevertheless, various other rare species have not been observed yet. Results on functional traits characterizing environmental adaptation and reproduction also underlined the differences between restoration plots and the reference site. Our study presents a ʽdynamic restoration approachʼ where managers evaluated the original factorial treatments after a decade and modified them by additional treatments where development was sub-optimal. Such additional treatments may have confounded the experimental design, but from a management perspective proved to be a promising option to establish species rich grassland of high conservation value with a reasonable expenditure of time.
15 δ N signals in plant and soil material integrate over a number of biogeochemical processes
related to nitrogen (N) and therefore provide information on net effects of multiple
processes on N dynamics. In general little is known in many grassland restoration projects
on soil–plant N dynamics in relation to the restoration treatments. In particular, 15 δ N signals
may be a useful tool to assess whether abiotic restoration treatments have produced the
desired result. In this study we used the range of abiotic and biotic conditions provided
by a restoration experiment to assess to whether the restoration treatments and/or plant
functional identity and legume neighborhood affected plant 15 δ N signals. The restoration
treatments consisted of hay transfer and topsoil removal, thus representing increasing
restoration effort, from no restoration measures, through biotic manipulation to major
abiotic manipulation. We measured 15 δ N and %N in six different plant species (two nonlegumes and four legumes) across the restoration treatments. We found that restoration
treatments were clearly reflected in 15 δ N of the non-legume species, with very depleted
15 δ N associated with low soil N, and our results suggest this may be linked to uptake of
ammonium (rather than nitrate). The two non-legume species differed considerably in their
15 δ N signals, which may be related to the two species forming different kinds of mycorrhizal
symbioses. Plant 15 δ N signals could clearly separate legumes from non-legumes, but our
results did not allow for an assessment of legume neighborhood effects on non-legume
15 δ N signals. We discuss our results in the light of what the 15 δ N signals may be telling
us about plant–soil N dynamics and their potential value as an indicator for N dynamics in
restoration.
Farmland bird populations are in a deep crisis across Europe. Agri-environment schemes (AES) were implemented by the European Union to stop and reverse the general decline of biodiversity in agricultural landscapes. In Germany, flower strips are one of the most common AES. Establishing high-quality perennial wildflower strips (WFS) with species-rich native forb mixtures from regional seed propagation is a recent approach, for which the effectiveness for birds has not yet been sufficiently studied. We surveyed breeding birds and vegetation on 40 arable fields with WFS (20 with single and 20 with aggregated WFS) and 20 arable fields lacking WFS as controls across Saxony-Anhalt (Germany). Additionally, vegetation composition, WFS quantity and landscape structure (e.g. distance to nearest woody element) were considered in our analyses. All WFS were established with species-rich native seed mixtures (30 forbs) in agricultural practice as AES. Arable fields with WFS had a higher species richness and territory density of birds than controls, confirming the effectiveness of this AES. A forb-rich vegetation was the main driver promoting birds. Flower strip quantity at the landscape level had positive effects only on bird densities, but also single WFS achieved benefits. A short distance from WFS to woody elements increased total bird species richness. However, the density of farmland birds, which are target species of these AES, were negatively affected by the proximity and proportion of woody elements in the vicinity. The effect of the proportion of non-intensively used open habitats and overall habitat richness was unexpectedly low in the otherwise intensively farmed landscape. Species-rich perennial WFS significantly promoted breeding birds. Successful establishment of WFS, resulting in high-quality habitats, a high flower strip quantity as well as implementation in open landscapes were shown to maximise the effectiveness for restoring declining and AES target farmland birds.
1. Flower strips are a fundamental part of agri-environment schemes (AESs) introduced by the European Union to counteract the loss of biodiversity and related ecosystem services in agricultural landscapes. Although vegetation composition of the strips is essential for most fauna groups, comprehensive studies analysing vegetation development and influencing factors are rare.
2. From 2017 to 2019, we investigated the vegetation composition of 40 perennial wildflower strips (WFSs) implemented in 2015 or 2016, and 20 cereal fields without WFS across Saxony-Anhalt, Germany. We analysed environmental factors on plot (cover of grasses, shading, soil fertility) and four landscape-scale levels (habitat diversity, proportion of WFS and open habitats). The provision of nectar and pollen resources was estimated by the newly developed Pollinator Feeding Index (PFI). All strips had been implemented by farmers as AES with species- rich seed mixtures comprising 30 native forbs.
3. In all study years, forb species richness, cover and related nectar and pollen supply were much higher on WFSs than on controls, confirming the effectiveness of this AES. Although sown native forbs contributed the most to the high PFI values, spontaneously established forbs expanded the total range of species considerably, especially in winter and spring. While sown forb communities remained similar over time, spontaneous forbs showed a higher species turnover. Altogether, shading and grass cover had the greatest negative effect on the performance of the sown forbs. Landscape variables had only minor effects and were inconsistent in their importance across scale levels and years.
4. Synthesis and applications. Successfully established perennial wildflower strips (WFSs) sown with species-rich native seed mixtures provided a forb-rich and diverse vegetation throughout the AES funding period of 5 years. By supplying feeding resources for pollinators under various landscape situations, WFSs have significant potential to promote farmland biodiversity and related ecosyste services. We recommend the mandatory use of species-rich wildflower mixtures for perennial flower strips and to avoid their creation in heavily shaded field edges. Advisory services for farmers are necessary to prevent failures in WFS implementation and management and to improve their ecological effectiveness.