Using fine-scale field data modelling for planning the management of invasions of Oenothera stucchii in coastal dune systems

Invasive alien species risk assessment and adaptive management are often hindered by a lack of information for most species. This work aims at predicting the probability of successful establishment and invasion of Oenothera stucchii Soldano, a neophyte invasive species belonging to the sect. Oenothera subsect. Oenothera, in xerophilous grasslands of grey dunes. Based on fine-scale field data, we modelled O. stucchii presence/absence and abundance as a function of environmental factors, human disturbance, and attributes of the recipient community through a zero-inflated Poisson model. The invasion success of O. stucchii depended on a combination of factors which differed when considering either the patterns of occurrence (species presence/absence) or those of species abundance. While human-driven disturbance strongly influenced the probability of presence/absence of O. stucchii, patterns of abundance were mostly driven by a combination of environmental and biotic features. Attributes of the recipient community remarkably influenced both O. stucchii presence and abundance. Based on fine-scale field data, we determined the mechanisms which drive the spatial patterns of presence and abundance of O. stucchii in xerophilous grasslands and provided quantitative thresholds to identify the most susceptible areas of grey dune habitats prone to invasion, which combine human disturbance (distance from the nearest beach access), attributes of the resident community (resident vegetation cover and structure), and environmental disturbance (foredune ridge height). These results provide useful insights to be used to plan cost-effective measures to prevent O. stucchii establishment and spread in sandy coastal systems. Our model may also be applied to closely related congener species included in the subsect. Oenothera, sharing similar biological and ecological traits

Ecological intensification: multifunctional flower strips support beneficial arthropods in an organic apple orchard

Flower strips are a fundamental part of agri-environment schemes in the Common Agricultural Policy (CAP). Although vegetation is central for many arthropod groups, a few studies have evaluated the effects of flower strip structural and functional attributes on arthropod communities. In this study, we explored the relationship between flower strip attributes and the abundance of different arthropod functional groups in annual flower strips located in an organic apple orchard. We surveyed plant and arthropod communities in 30 1 m × 6 m plots. In each plot, we collected data on species composition and vegetation structure (e.g., total cover, density, number of floral displays). For each plant species, we also retrieved data on leaf palatability and nutritional value. Arthropods were collected using sweep netting technique. Structural and functional attributes of the flower strip revealed a crucial role in regulating arthropod abundance, which however depended on the specific arthropod functional group. We identified three main attributes (plant species richness, composition, and vegetation density) of flower strips that should be considered when implementing multifunctional flower strips. Specifically, plant species richness to ensure complementarity of resources and niches, plant species composition to ensure complementary floral resources, and vegetation density to ensure sheltering microhabitats and suitable microclimatic conditions and to increase the density of floral resources. Our results suggest that by considering structural and functional attributes of flower strips, it is possible to design multifunctional flower strips with greater effectiveness as measures for ecological intensification

Increasing the germination percentage of a declining native orchid (Himantoglossum adriaticum) by pollen transfer and outbreeding between populations

The declining native orchid Himantoglossum adriaticum H. Baumann is a European endemic of priority interest (92/43/ EEC, Annex II). Northern Italian populations of H. adriaticum are small and isolated, with depressed seed set. Given the important implications for plant population conservation, we tested the hypothesis that artificial pollen transfer (hand-pollination) and outbreeding between populations increases fruit set and seed germination percentage. The background fruit set and in vitro germination rates were determined for ten reference populations. An artificial cross-pollination experiment included (a) pollen transfer from one large population to two small and isolated populations; (b) pollen transfer between two small but not isolated populations; (c) within-population pollen transfer (control). All seeds were sown on a modified Malmgren's medium and cultured in a controlled environment. Germination percentage was compared using a Kruskal-Wallis anova. The background fruit set (mean = 18%) and germination (<5%) rates were consistently low across populations. Fruit set after hand-pollination was consistently 100%. Pollen transfer from the largest population to smaller populations resulted in an increase in total germination ranging from 0.9% to 2.9%. The largest increase in germination occurred between small-sized and less isolated populations (from 1.7% to 5.1%). The results of pollen transfer between the small populations are particularly encouraging, as the mean increase in germination was almost four times that of the control. Outbreeding can be considered a valuable tool to increase genetic flow and germination in natural populations, limit the accumulation of detrimental effects on fitness driven by repeated breeding with closely-related individuals, thereby increasing the possibility of conservation of rare or endangered species

The germination niche of coastal dune species as related to their occurrence along a sea–inland gradient

Aims: The early phases in the life cycle of a plant are the bottleneck for successful species establishment thereby affecting population dynamics and distribution. In coastal environments, the spatial pattern of plant communities (i.e. vegetation zonation) follows the ecological gradient of abiotic stress changing with the distance from the sea. This pattern has been mainly explained based on the adaptation and tolerance to the abiotic stress of adult plants. However, the adult niche may considerably differ from the germination niche of a plant species. The aim of this work was to investigate to what extent abiotic factors (specifically salinity, temperature, nitrogen and their interactions) constrain seed germination along the sea–inland gradient. Location: Latium coast (Central Italy). Methods: Germination tests were performed on seeds of focal species of three different plant communities which establish at increasing distances from the coastline: Cakile maritima subsp. maritima, Elymus farctus, Crucianella maritima. We tested increasing concentrations of NaCl (one of the main abiotic factors which decrease across the sea–inland gradient), and their interactions with temperature and KNO3, to consider other factors which drive germination processes. Results: The tolerance to salinity significantly decreased in relation to the position of species along the coastal zonation. Crucianella maritima was shown to be the least tolerant species, having a decrease in germination >80% across all conditions. KNO3 significantly (although slightly) increased the germination percentage in Cakile maritima subsp. maritima and Elymus farctus. When combined with NaCl, KNO3 alleviated the negative effects of salinity only in Cakile maritima subsp. maritima. Conclusions: The germination responses to the interaction among the tested factors suggest that the germination niche may explain vegetation zonation filtering species at their early stages. Quantifying environmental niches in different phases of the life cycle of plants may provide important insights into community assembly processes

Local versus landscape-scale effects of anthropogenic land-use on forest species richness

The study investigated the effects of human-induced landscape patterns on species richness in forests. For 80 plots of fixed size, we measured human disturbance (categorized as urban/industrial and agricultural land areas), at ‘local’ and ‘landscape’ scale (500m and 2500m radius from each plot, respectively), the distance from the forest edge, and the size and shape of the woody patch. By using GLM, we analyzed the effects of disturbance and patch-based measures on both total species richness and the richness of a group of specialist species (i.e. the ‘ancient forest species’), representing more specific forest features. Patterns of local species richness were sensitive to the structure and composition of the surrounding landscape. Among the landscape components taken into account, urban/industrial land areas turned out as the most threatening factor for both total species richness and the richness of the ancient forest species. However, the best models evidenced a different intensity of the response to the same disturbance category as well as a different pool of significant variables for the two groups of species. The use of groups of species, such as the ancient forest species pool, that are functionally related and have similar ecological requirements, may represent an effective solution for monitoring forest dynamics under the effects of external factors. The approach of relating local assessment of species richness, and in particular of the ancient forest species pool, to land-use patterns may play an important role for the science-policy interface by supporting and strengthening conservation and regional planning decision making

Habitat quality assessment through a multifaceted approach: the case of the habitat 2130* in Italy

Sand dune perennial grasslands are valuable coastal habitats, considered among those with major conservation concerns. The priority EU habitat 2130* has an almost continuous distribution area along the coasts of Northern Europe and the Black Sea. In the Mediterranean basin it is found only along the North Adriatic coast, isolated from the rest of the distribution area, thereby representing a unique aspect of the habitat variability. The first aim of this study was to evaluate the conservation status of the EU habitat 2130* by using the concept of ‘diagnostic species pool’ and a ‘reference state’ approach by comparing extant plant community attributes to the expected condition in the absence of major environmental and anthropogenic disturbances. The second aim was to investigate the effects of natural and anthropogenic factors on EU habitat 2130* conservation status. Our study allowed to evidence an overall bad conservation status of the habitat, with a generalized decrease in the average species richness and modifications of the habitat structure. The concepts of ‘diagnostic species pool’ and ‘reference state’ turned out as the most straightforward tools to assess the conservation status. While geomorphological features, in particular dune width, and human disturbance revealed significant correlation with the conservation status, sedimentological data were not useful to detect community’s quality changes. To preserve the EU 2130* priority habitat, representing a peculiar element of the North Adriatic coast, the entire dune system integrity should be pursued, avoiding direct foredune destruction and other actions preventing dune development. In addition to this, the access to the dune system should be managed in order to protect the sensitive dune vegetation from trampling impacts

Pollination and dispersal trait spectra recover faster than the growth form spectrum during spontaneous succession in sandy old‐fields

Question: Spontaneous succession is the most natural and cost‐effective solution for grassland restoration. However, little is known about the time required for the recovery of grassland functionality, i.e., for the recovery of reproductive and vegetative processes typical of pristine grasslands. Since these processes operate at different scales, we addressed the question: do reproductive and vegetative processes require different recovery times during spontaneous succession? Location: Kiskunság sand region (Central Hungary). Methods: As combinations of plant traits can be used to highlight general patterns in ecological processes, we compared reproductive (pollination‐ and dispersal‐related) and vegetative (growth form) traits between recovered grasslands of different age (<10 years old; 10–20 years old; 20–40 years old) and pristine grasslands. Results: During spontaneous succession, the reproductive trait spectra became similar to those of pristine grasslands earlier than the vegetative ones. In arable land abandoned for 10 years, pollination‐ and dispersal‐related trait spectra did not show significant difference to those of pristine grasslands; anemophily and anemochory were the prevailing strategies. Contrarily, significant differences in the growth form spectrum could be observed even after 40 years of abandonment; in recovered grasslands erect leafy species prevailed, while the fraction of dwarf shrubs and tussock‐forming species was significantly lower than in pristine grasslands. Conclusions: The recovery of the ecological processes of pristine grasslands might require different amounts of time, depending on the spatial scale at which they operate. The reproductive trait spectra recovered earlier than the vegetative one, since reproductive attributes first determine plant species sorting at the regional level towards their respective habitats. The recovery of the vegetative trait spectrum needs more time as vegetative‐based interactions operate on a smaller spatial scale. Thus, vegetative traits might be more effective in the long‐term assessment of restoration success than the reproductive ones

Phenotypic differentiation among native, expansive and introduced populations influences invasion success

Aim: Humans influence species distributions by modifying the environment and by dispersing species beyond their natural ranges. Populations of species that have established in disjunct regions of the world may exhibit trait differentiation from native populations due to founder effects and adaptations to selection pressures in each distributional region. We compared multiple native, expansive and introduced populations of a single species across the world, considering the influence of environmental stressors and transgenerational effects. Location: United States Gulf and Atlantic coasts, United States interior, European Atlantic and Mediterranean coasts, east coast of Australia. Taxon: Baccharis halimifolia L. (eastern baccharis). Methods: We monitored seed germination, seedling emergence, survival and early growth in a common garden experiment, conducted with over 18,200 seeds from 80 populations. We also evaluated the influence of environmental stress and maternal traits on progeny performance. Results: Introduced European Atlantic populations had faster germination and early growth than native populations. However, this was not the case for the more recently naturalized European Mediterranean populations. Introduced Australian populations grew faster than native populations in non-saline environments but had lower survival in saline conditions commonly encountered in the native range. Similarly, expansive inland US populations germinated faster than coastal native populations in non-saline environments but grew and germinated more slowly in saline environments. Maternal inflorescence and plant size were positively related with seed germination and seedling survival, whereas flower abundance was positively correlated with seedling early growth and survival. However, maternal traits explained a much lower fraction of the total variation in early demographic stages of B. halimifolia than did distributional range. Main conclusions: Phenotypic differentiation could allow B. halimifolia to adapt to different biotic and abiotic selection pressures found in each distributional range, potentially contributing to its success in introduced and expansive ranges

Pollination networks along the sea-inland gradient reveal landscape patterns of keystone plant species

Linking the functional role of plants and pollinators in pollination networks to ecosystem functioning and resistance to perturbations can represent a valuable knowledge to implement sound conservation and monitoring programs. The aim of this study was to assess the resistance of pollination networks in coastal dune systems and to test whether pollination interactions have an explicit spatial configuration and whether this affect network resistance. To this aim, we placed six permanent 10 m-wide belt transects. Within each transect we placed five plots of 2 m x 2 m, in order to catch the different plant communities along the dune sequence. We monitored pollination interactions between plants and pollinators every 15 days during the overall flowering season. The resulting networks of pollination interactions showed a relatively low degree of resistance. However, they had a clear spatial configuration, with plant species differently contributing to the resistance of pollination networks occurring non-randomly from the seashore inland. Our results evidenced that beside contributing to the creation and maintenance of dune ridges, thereby protecting inland communities from environmental disturbance, plant species of drift line and shifting dune communities have also a crucial function in conferring resistance to coastal dune pollination networks