Effects of grassland management on plants and invertebrates in Transylvania, Romania : a threat to local biodiversity hotspots

Abstract: Recent changes in agriculture (intensification or abandonment) have resulted in a critical reduction of steppe‐like grasslands in Eastern Europe. These grasslands harbor an extraordinarily high diversity of plants and invertebrates, including endemics, and are considered refugia for numerous threatened open‐land species. We examined species richness, and abundance, proportion of open‐land, endemic and threatened vascular plants, gastropods, and diurnal and nocturnal Lepidoptera in six different vegetation types all originating from steppe‐like grasslands in Transylvania, Romania. Vegetation types included extensively grazed pastures (initial stage), three seral stages of succession (early stage of abandoned grassland, abandoned grassland with shrubs, and mature forest), and two human‐made grassland alterations, namely abandoned vineyards and Pinus plantations. A total of 852 species (291 vascular plants, 24 gastropods, 129 diurnal and 408 nocturnal Lepidoptera) were found in the 22 study sites. The four taxonomic groups differed in their response to the abandonment of steppe‐like grassland, except that species richness of plants and diurnal Lepidoptera were positively correlated. The complementarity of species composition increased with successional age in all taxonomic groups examined. The number of characteristic open‐land species decreased with successional age in plants and gastropods. All investigated vegetation types harbored threatened (red‐listed) species. Endemic species were found in all vegetation types except mature forests and Pinus plantations. All Transylvanian endemics and the majority of threatened species found were open‐land species. Extensively cultivated vineyards, which have been abandoned for two to three decades, also maintained high plant and invertebrate diversities, comparable to those of the corresponding stages of grassland succession. In contrast, Pinus plantations (a recent grassland alteration) have changed habitat quality and will have a devastating effect on the unique, indigenous diversity of these steppe‐like grasslands as soon as the canopy closes. To prevent losses of characteristic species, we suggest a rotational grassland management program that maintains different seral stages. Succession to mature forest and additional Pinus plantations should be prevented.

Effects of abandonment of subalpine hay meadows on plant and invertebrate diversity in Transylvania, Romania

Plant-diversity hotspots on a global scale are well established, but smaller local hotspots within these must be identified for effective conservation of plants at the global and local scales. We used the distributions of endemic and endemic-threatened species of Myrtaceae to indicate areas of plant diversity and conservation importance within the Atlantic coastal forests (Mata Atlântica) of Brazil. We applied 3 simple, inexpensive geographic information system (GIS) techniques to a herbarium specimen database: predictive species-distribution modeling (Maxent); complementarity analysis (DIVA-GIS); and mapping of herbarium specimen collection locations. We also considered collecting intensity, which is an inherent limitation of use of natural history records for biodiversity studies. Two separate areas of endemism were evident: the Serra do Mar mountain range from Paraná to Rio de Janeiro and the coastal forests of northern Espírito Santo and southern Bahia. We identified 12 areas of approximately 35 km(2) each as priority areas for conservation. These areas had the highest species richness and were highly threatened by urban and agricultural expansion. Observed species occurrences, species occurrences predicted from the model, and results of our complementarity analysis were congruent in identifying those areas with the most endemic species. These areas were then prioritized for conservation importance by comparing ecological data for each.

Semi-natural grasslands including hay meadows belong to the most species-rich habitats in central Europe and are therefore of high conservation value. The high biodiversity of these grasslands has been maintained for many centuries through the regular disturbance by traditional management practices. In the Valais, an arid mountain region of Switzerland, traditional management of hay meadows includes irrigation by open water channels. In the past decades, however, the traditional irrigation technique was increasingly replaced by more efficient sprinkler-irrigation systems or irrigation was stopped on marginal and poorly accessible areas. Within the scope of this thesis, four studies were conducted to investigate different aspects of these changes in meadow irrigation. The aim of the first study was to examine whether land-use abandonment resulting from the cessation of irrigation influenced the biodiversity of hay meadows in the Valais. For this purpose, plant and gastropod surveys were conducted in three serial stages of succession (hay meadows, early abandoned meadows and young forests). Meadow abandonment resulted in an increase in gastropod species richness and a loss of plant and gastropod species characteristic for open grassland habitats. Furthermore, functional traits of plants (plant height, the start of seed shedding and the type of reproduction) and gastropods (shell size) were affected by abandonment. Traditional meadow irrigation is assumed to distribute the water more heterogeneously than sprinkler irrigation, which might affect meadow biodiversity as well as the distribution of plants in a small scale. The aim of the second study was to examine whether the change from traditional to sprinkler irrigation affected the local biodiversity (plants and gastropods) of hay meadows in the Valais. A high plant species richness was found in the hay meadows investigated. The diversity and composition of plant and gastropod species did not differ between traditionally and sprinkler-irrigated meadows. However, the installation of sprinkler systems resulted in an increase in the grass-to-forb ratio and affected the leaf distribution and the start of seed shedding in plants. The third study aimed to investigate whether the change in irrigation technique affected the small-scale distribution of plants and soil characteristics in these hay meadows. Three sampling plots consisting of 13 subplots of increasing size were installed in traditionally and sprinkler-irrigated meadows to assess plant species richness and soil characteristics within subplots. The type of irrigation technique did not affect the shape of the plant species-area relationship. Furthermore, spatial autocorrelation in the soil characteristics examined was low and their small-scale distributions were mostly not influenced by the irrigation technique. These findings indicate a pronounced small-scale heterogeneity in the distribution of plant species and soil characteristics in the hay meadows investigated. Therefore, as practiced in our study areas, the distribution of water by sprinklers might be less homogenous than commonly assumed. The abandonment of traditional management practices of semi-natural grasslands is suggested to result in a reduced landscape heterogeneity, which in turn might contribute to the loss of local plant diversity. The fourth study aimed to investigate whether the change from traditional to sprinkler irrigation resulted in alterations in the surrounding landscape of species-rich hay meadows. Furthermore, we asked if plant diversity of differently irrigated meadows is influenced by landscape composition and the heterogeneity of the surrounding landscape. Landscape composition was more diverse for traditionally than for sprinkler-irrigated meadows, but did not differ prior to the installation of sprinklers. A diverse small-scale landscape composition in the close surroundings of hay meadows had a positive effect on the number of generalists but not on total plant species richness or the number of specialists. Finally, sprinkler-irrigated meadows had an increased number of generalist plant species. The findings of this thesis suggest that the installation of sprinklers did not affect the local species richness of plants and gastropods in the hay meadows investigated. Nevertheless, the change in irrigation technique influenced functional aspects of plant diversity (plant traits, grass-to-forb ratio and generalist species). Furthermore, the installation of sprinklers was associated with a homogenization of the landscape, which may eventually result in an intensification of land use. For the conservation of the biodiversity of these hay meadows it is recommended to maintain the relatively extensive irrigation and management practices.

Nutrient-poor, dry calcareous grasslands in Central Europe harbour an extraordinary high diversity of plants and invertebrates. Consequently, they are of high conservation value. However, changes in agriculture (intensification or abandonment) have resulted in a dramatic reduction of semi-natural grasslands in the twentieth century. Today, dry grasslands are among the most endangered habitats. Furthermore, these grasslands are frequently fragmented and surrounded by forest or intensively cultivated agricultural areas. Semi-natural grasslands are fragile because their maintenance depends on traditional farming techniques. In order to avoid any loss of species by inappropriate land use, it is important to assess the responses of threatened species to particular types of grassland management. Although different types of present and past pasture management are known to affect the species richness and composition of plant communities, knowledge of the effects on invertebrates is limited. In particular, no studies exist on the influence of different types of pasture management on animals with limited mobility, such as gastropods. In the present thesis, I examined the effects of different pasture management practices on the snail community in dry, nutrient-poor grasslands of the Swiss Jura mountains, where extensive grazing with low stocking rate and without use of fertilizers is a traditional form of grassland management. I assessed the snail communities in extensive pastures grazed by horses, cattle or sheep, in cattle pastures with different management intensity and in extensive pastures with different management history in the last 55 years. Furthermore, gastropod species richness and abundance were examined in transects running from extensive pastures through gradual or abrupt forest edges into the forest interior. Grazing by different livestock species did not affect the species richness, abundance and species composition of land snails. However, independent of livestock species, snail species richness, abundance and number of red-listed species decreased with increasing grazing intensity. Furthermore, cattle pastures without fertilizer application and with low grazing intensity harboured more snail species and more threatened snails than pastures with annual addition of fertilizer and higher grazing intensity. Management intensity had also a negative influence on individual snail species (Cochlicopa lubricella, Truncatellina cylindrica, Vitrina pellucida, Helicella itala and Helix pomatia). Former changes in pasture use for a period of 10–40 years altered the present-day snail fauna. Past shrub cover had a negative effect on the total number of snail species and individuals, the number of open-land species and individuals and the number of red-listed individuals. Former use of fertilizer and higher grazing intensity reduced red-listed species and individuals and altered the snail community. The grassland snail communities of the pastures changed distinctly to forest communities at the first bushes or trees of edges towards forest interior irrespective of the type of forest edge. In pastures, at a distance of 10 m from gradual forest edges, more open-land snail species were found than at the corresponding distance from abrupt forest edges. Furthermore, ecotones of gradual forest edges harboured more open-land individuals than those of abrupt forest edges. For the conservation of grassland land snail communities, it does not matter whether pastures are stocked with horses, cattle or sheep, provided the grazing intensity is low. To preserve the threatened snail species in dry, nutrient-poor grasslands, a network of pastures should be managed without fertilization and grazing intensity should not exceed 180 LU.ha-1.d (product of livestock units per hectare and grazing days). Furthermore, to recover the typical grassland snail community in shrub cleared pastures or former fertilized pastures, the connection between intact pastures and grasslands under restoration should be improved by creating and maintaining new semi-natural areas and by exchanging livestock among these areas during the grazing season. Since shadowing of trees and alterations of the microclimate close to the forest edge may reduce the actual size of small grassland fragments, encroaching shrubs should be regularly removed and gradual forest edges created and maintained.

Extensively managed pastures harbour rare and endangered species and have a decisive role in maintaining grassland biodiversity. Traditional herding of local robust cattle breeds is considered as a feasible tool for preserving these habitats. We studied the scale-dependent effects of grazing on the species richness and composition of three dry grassland types in the Great Hungarian Plain: Achilleo setaceae-Festucetum pseudovinae and Artemisio santonici-Festucetum pseudovinae alkaline grasslands, and Potentillo arenariae-Festucetum pseudovinae sand grassland. We asked the following questions: (1) Does extensive grazing have a scale-dependent effect on plant species richness of alkaline and sand grasslands? (2) How does grazing affect the proportion of specialists, generalists and weeds in the three grassland types? We sampled ten sites of each grassland type, including five extensively grazed and five non-grazed sites (altogether we had 30 sites). We used a series of nested plots each consisting of 10 plots from the size of 0.01 m² to 16 m². We revealed that grazing has contrasting effects in the three grassland types, and had a considerable effect on their species richness even at small scales. In both alkaline grassland types, total species richness was overall higher in grazed plots but it increased in a similar manner for both ungrazed and grazed habitats across plot sizes. Small-scale heterogeneity likely due to the uneven distribution of grazing, trampling and defecation together with mitigated rate of competition allowed more species to co-exist even at small scales in grazed alkaline grasslands. Grazing increased the richness of specialists, but likely due to the salt stress, establishment of weeds was hampered. Open gaps formed by trampling likely supported the establishment of several specialist species such as Plantago tenuiflora and Puccinellia limosa which are typical to open alkali grasslands. Contrary, in sand grasslands, we did not detect any effect of grazing on total species richness, likely due to the adverse effect of grazing on the species richness of specialists and weeds. In contrast with the former findings we detected significantly higher species richness in 0.01 m² and 0.0625 m² plots in the grazed sand grasslands, but found no differences at larger scales. Whilst species richness of specialists was significantly decreased, richness of weeds was increased by grazing. Decrease in the specialist species richness was likely due to the lack of their evolutionary adaptation to grazing. Degradation caused by grazing and trampling together with the propagule pressure from the neighbouring anthropo-genic habitats resulted in an increased richness of weeds in the grazed sites.

The warming global climate is threatening terrestrial ecosystem stability, including plant community structure and diversity. However, it remains unclear how distribution, richness, and turnover of plant species are impacted by warming and wetting in northern China. In the present study, species distribution models were applied to predict the spatial distribution of 5111 plant species based on 111,071 occurrence records in northern China. Additionally, variations in species richness and turnover rates were predicted for 2100 under 3 scenarios. The results indicated that approximately 70% of plant species will expand in their distribution, resulting in an increase in species richness. These changes will be driven mainly by temperature seasonality (TSN), annual precipitation (MAP), and mean temperature of the coldest quarter (MTCQ). However, about 30%-40% of the species will face extinction risks, including a considerable number of endemic and Red-Listed species, and suitable habitat loss (LSH) will exceed 30%. Narrow-ranging species will be more likely to lose a larger percentage of their suitable habitats than wide-ranging species, highlighting their sensitivity to environmental changes. Importantly, it emerged that species turnover rates will increase linearly with ecological vulnerability at the grid level, indicating that community structure and species composition are easily affected by climate change in ecologically vulnerable areas. Therefore, biodiversity hotspots with high species richness in the southern study areas, as well as regions exhibiting both fast species turnover and significant ecological vulnerability, should be prioritized for conservation. These findings provide insights into how species composition and richness in plant communities vary with global climate change and provide effective ecological conservation and management strategies.

Dispersal traits as indicators of vegetation dynamics in long-term old-field succession

Knowledge of spatial patterns of species richness (SR) is highly relevant for theoretical research in ecology and the development of conservation plans. In Poland, despite a long tradition of botanical surveys, vascular plant SR has not been mapped, nor have the correlations in richness among different plant species groups been explored at the entire country scale. Here, we used a recently published data set to examine spatial patterns and relationships among the joined SR of vascular plant species, including native species, archaeophytes, neophytes, and species with high conservation value (i.e., red-list species). The basic spatial unit employed was a 10 × 10 km grid from the Atlas of Distribution of Vascular Plants in Poland (ATPOL). We found that SR of native species and archaeophytes, neophytes, and red-list species were positively correlated. The main patterns of SR and the percentage of particular groups in the joined SR were based on three components: (1) gradient of overall SR, (2) invasion level, and (3) peculiarity of flora in some regions resulting from the high number and proportion of rare species that often have high conservation value (red-list species). In general, northeastern Poland was species-poor, while the Carpathian Mountain range, the uplands in southern Poland, and some parts of Wisła River valley had the highest SR concentrations. e location of SR hotspots usually did not overlap with the existing national parks system. The correlations among native SR, high conservation value species, and neophyte SR suggest that biological invasions are among the most important threats to vascular plant diversity in Poland. Finally, despite likely biases in SR assessments, we demonstrated that the presented maps seem to reflect general ecological gradients influencing vascular plant distribution in Poland.

Vegetation diversity, distribution and species endemism were studied in high altitude (>3300 m) Himalayan plateau in Northern Pakistan. A heterogeneous vegetation structure and distribution was observed due to complex environmental variables. A total of 83 species belonging to 31 families were recorded from the area. The recorded range of species diversity (1.02 to 2.17) and species richness (1.19 to 1.97) was very low as compared to other Himalayan regions. Detrended correspondence analyses (DCA) revealed slope steepness and associated moisture gradient as the main limiting factors controlling vegetation distribution and community structure. Species diversity and richness were negatively whereas evenness was positively correlated with slope steepness and moisture content. Chorological spectrum of vegetation revealed a high (41%) level of species endemism with 34 recorded Himalayan endemic species. Dominance of unpalatable species indicated prevalent impacts of overgrazing on the local flora and possible threats to endemic plant diversity. The high species endemism suggests the conservative value of the area. Key words: Deterrended correspondence analyses, Himalayas, moisture gradient, species endemism, slope steepness.

Passive restoration of subtropical grasslands leads to incomplete recovery of ant communities in early successional stages

Invasive alien species cause major changes to ecosystem functioning and patterns of biodiversity, and the main factors involved in invasion success remain contested. Using the Mediterranean island of Crete as a case study, we present a framework for analyzing spatial data of alien species distributions, based on environmental predictors, aiming to gain an understanding of their spatial patterns and spread. Mediterranean islands are under strong ecological pressure from invading species due to their restricted size and increased human impact. Four hypotheses of invasibility, the ‘propagule pressure hypothesis’ (H1), ‘biotic resistance hypothesis vs. acceptance hypothesis’ (H2), ‘disturbance-mediated hypothesis’ (H3), and ‘environmental heterogeneity hypothesis’ (H4) were tested. Using data from alien, native, and endemic vascular plant species, the propagule pressure, biotic resistance versus acceptance, disturbance-mediated, and environmental heterogeneity hypotheses were tested with Generalized Additive Modelling (GAM) of 39 models. Based on model selection, the optimal model includes the positive covariates of native species richness, the negative covariates of endemic species richness, and land area. Variance partitioning between the four hypotheses indicated that the biotic resistance versus acceptance hypothesis explained the vast majority of the total variance. These results show that areas of high species richness have greater invasibility and support the acceptance hypothesis and “rich-get-richer” distribution of alien species. The negative correlation between alien and endemic species appears to be predominantly driven by altitude, with fewer alien and more endemic species at greater altitudes, and habitat richness. The negative relationship between alien and endemic species richness provides potential for understanding patterns of endemic and alien species on islands, contributing to more effective conservation strategies.

In this study we investigated the temporal variability of N-source utilization of pioneer plant species in different early successional stages of dry acidic grasslands. Current theory states that plant species occupy distinct ecological niches and that there are species-specific, temporal N-uptake patterns. We hypothesized that small-scale dynamics in the natural habitat may affect niche differentiation among plant species. We investigated N-uptake patterns of two co-occurring plant species from different functional groups (Corynephorus canescens, Rumex acetosella) under natural conditions using 15N-labeled nitrate and ammonium in three different early successional stages during early and late summer. We found (1) marked seasonal dynamics with respect to N-uptake and N-source partitioning, and (2) different uptake rates across successional stages but a similar N-form utilization of both species. Nitrate was the main N-source in the early and later successional stages, but a shift towards enhanced ammonium uptake occurred at the cryptogam stage in June. Both species increased N-uptake in the later successional stage in June, which was associated with increasing plant biomass in C. canescens, whereas R. acetosella showed no significant differences in plant biomass and root/shoot-ratio between successional stages. Ammonium uptake decreased in both species across all stages with increasing drought. Nevertheless, the peak time of N-uptake differed between the successional stages: in the early successional site, with the lowest soil N, plants were able to extend N-uptake into the drier season when uptake rates in the other successional stages had already declined markedly. Hence, we found a pronounced adjustment in the realized niches of co-occurring plant species with respect to N-uptake. Our results indicate that ecological niches can be highly dynamic and that niche sharing between plant species may occur instead of niche partitioning.

Local and landscape factors affecting communities of plants and diurnal Lepidoptera in black coal spoil heaps: Implications for restoration management

(1) In the subalpine region of Central Switzerland (Tavetsch Valley) studies were made of the day-active Lepidoptera faunas in different types of cultivated grassland, in various stages in the development of abandoned grassland and in woodlands (climax vegetation). (2) The results show a close correlation between bufferfly fauna and vegetation type concerning species composition and species richness of Lepidoptera. (3) Species richness of butterflies is highest in early abandoned stages and falls rapidly with the arrival of shrubs and trees. It is also high in traditionally lightly cultivated grassland (unfertilized mown and lightly grazed meadows), but it declines drastically with increasing intensity of cultivation. (4) In general, species richness of butterflies is closely correlated with species richness of vascular plants, but cultivation methods and the short time since abandonment (<5 years) of lightly cultivated grassland have strongly different influences on species richness of Lepidoptera and vascular plants. (5) The results are in contrast to former studies in Central Europe and parallel studies in England. (6) The natural primary habitats of butterflies living in the anthropogenetic types of vegetation investigated and the consequences for nature conservation are discussed.