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Within a species, the distance travelled by a particular diaspore depends on its morphology. In Poaceae, the presence of terminal sterile florets can lead to diaspore heteromorphism, which may influence dispersal. We tested the hypothesis that the presence of sterile florets favored dispersal in Bromus tectorum L., an invasive grass in the Western US. We used field and controlled experiments to study the dispersal of caryopses with and without sterile florets attached (respectively complex and simple diaspores), as well as pieces of inflorescence that detached from the mother plants. We considered both primary and secondary dispersal, as well as abiotic and biotic dispersal agents. The distance travelled by the diaspores and their attachment to animal fur were related to the presence and number of sterile florets. Abiotic agents moved diaspores over relatively short distances, both in terms of primary and secondary dispersal. A significant proportion of diaspores attached to fur, suggesting a potential for dispersal over long distances. Complex diaspores were better dispersers than simple ones (and pieces of inflorescence), and this pattern was consistent across the study. However, among complex diaspores, the number of sterile florets had little or no influence. Considering primary and secondary dispersal by abiotic and biotic agents provided a general picture of the dispersal ecology of B. tectorum . For all the dispersal steps and dispersal agents we studied, the presence of sterile florets favored dispersal. These results highlight the functional significance of diaspore heteromorphism induced by floret sterility in the dispersal of Poaceae. [ABSTRACT FROM AUTHOR]

In southeastern D. R. Congo, about 550 metallophytes grow on soils with high copper and cobalt concentrations, 57 of which are endemics to these metalliferous environments. About 70% of those endemics are considered threatened by destruction of habitats through mining activities. To provide guidelines for future restoration programs, the edaphic ecological niches of eight endemic metallophytes (i.e. copper endemics) were studied using a pragmatic sampling method adapted for urgent conservation needs. Niches were modelled using violin plot along Cu, Co and C:N gradients representing the two main independent edaphic gradients among nine edaphic variables (C, N, C:N, K, P, pH, Co, Cu, and Mn). Copper endemics presented distinct edaphic niches along the copper and cobalt gradients, but differentiation was lower along the C:N gradient. In addition, edaphic elements presented covariations among them and metalliferous soils had higher nutrient and element content compared to the non-metalliferous soils of the region dominated by the Miombo woodland. The complexity of the soil composition and the edaphic niches of copper endemics revealed an important challenge in the implementation of the species conservation and the habitat restoration strategies of post-mining sites. [ABSTRACT FROM AUTHOR]

In last decades, farmland biodiversity came under large threat. To counteract farmland biodiversity loss and other environmental impacts of intensive agriculture, European farmers can apply Agri-environmental schemes. One of these is the creation of flower strips, a part of the cropping field where flowers are sown or naturally settled. Flower strips are known to increase biodiversity in the agricultural landscape, notably attracting specific insects groups, such as pollinators and natural enemies that can provide valuable pollination and biocontrol services to the crop. However, the plant species composition and management of the strips can have a large influence on the identity and amount of useful insects present in the strips, suggesting the need to develop tailored flower strips to maximize the services delivered. Functional diversity (FD) is sometimes proposed as a promising approach, focusing on plant functional traits rather than plant species itself. Yet, it is not certain that sowing a set of plant species results in the desired vegetation with the desired functional trait composition. Species from soil seed bank or dispersing from neighboring vegetation can settle in the strip, while sown species might not always be equally adapted to local conditions. To test this, we developed seed mixtures with four different levels of FD, based on flower traits, and sew them as flower strips in a conventional arable field. We monitored the vegetation to calculate the FD of the realized vegetation. While the absolute FD values of the realized vegetation were lower than the expected FD values, the realized vegetation showed the same FD gradient as expected from the sown mixtures, indicating that it is possible to manipulate FD in flower strips. [ABSTRACT FROM AUTHOR]

Reducing pesticide use is one the major issues of today's agriculture. Among other possibilities, attracting and conserving pest natural enemies in agricultural landscapes by providing them habitats is promising. Wildflower strips (WFS) sown at field margins are one of these potential habitats. They are known to attract and conserve a large diversity of insects, as they provide them food resources such as pollen and nectar, as well as shelter and overwintering sites. However, the risk of attracting insect pests at field margins may represent an obstacle to their adoption by farmers. Conversely, it would be interesting if such WFS could play the role of pest trap crops. In an experimental field sown with WFS intercropped with oilseed rape (OSR) ( Brassica napus L.), its coleopteran pests were trapped in both WFS and OSR using yellow pan traps between April and June 2014. More than 130 000 Meligethes spp., Ceutorhynchus spp. and Psylliodes chrysocephalla (L.) adults were trapped. Meligethes spp., Ceutorhynchus spp. were significantly more abundant in the OSR compared with WFS when adults emerged and populations reached their abundance peak. Before and between these periods, the few adults trapped were significantly more abundant in the WFS compared with the OSR. Concerning P. chrysocephala , too few individuals were caught for analysis. Results showed that OSR was more attractive than WFS when coleopteran pests were abundant. In this study, WFS sown for insect conservation may neither favour insect pest conservation at field margin, nor be considered as trap crops. [ABSTRACT FROM AUTHOR]

Alien plant species invasion depends on biotic and abiotic conditions that can represent environmental barriers as compared to their native range conditions. Specifically, little is known about how alien plant species distribute along the urban-to-rural gradients based on their native climatic conditions, and how environmental conditions along these gradients could influence intraspecific trait variation. We studied the distribution of eight woody alien plant species from contrasted native range climates along urban-to-rural gradients in European areas with a temperate climate (hereafter termed oceanic Europe). During two consecutive summers and in the Belgian part of oceanic Europe, we then measured their intraspecific trait variation using the nitrogen balance index (NBI), chlorophyll content, flavonols index, specific leaf area (SLA) and internode space. Urban-to-rural gradients were characterized by a system of local climate zones (LCZ), the percentage of artificially sealed surfaces (urbanity) and the sky view factor (SVF). We found that the distribution of studied species in the LCZ classes was highly dependent on the climate of their native range, with species from warm climates occurring more in the most urban areas while the ones from cool climates preferred the more rural or natural areas. However, their intraspecific trait variation was not related to the LCZ class in which they grew, nor to their native climate. Instead, we found a surprisingly consistent effect of shielded environments (low SVF) along the entire urban-to-rural gradient on leaf and development traits. Such environments induced a lower leaf flavonols index and higher NBI and SLA, suggesting a shade response and possibly lower heat and drought stress. Our results show that although woody alien plant species from warmer or cooler native climates distributed differently along the urbanization gradient in oceanic Europe, they did not show contrasted intraspecific trait variation. Nevertheless, our findings highlight that even if the woody alien plant species from cooler native ranges are currently more present in the most natural areas, special attention should be paid to woody alien plant species from warmer native ranges that are yet restricted to the most urban areas and could potentially have severe impacts in the future when the barriers to their spread weaken with climate change. [ABSTRACT FROM AUTHOR]

An individual distance-independent girth increment model for pure stands of Douglas-fir (Pseudotsuga menziesii (MIRB.) FRANCO), comprising two equations, is presented. The data used to fit the model were collected from 1007 trees in 42 plots installed in regularly stocked and even-aged stands located in Wallonia (southern Belgium). Both equations predict girth increment from individual girth, dominant height, basal area per hectare, stand mean girth and variables linked to site fertility. These last variables are the site index H50 in the first equation, and a combination of mean annual rainfall and altitude in the second. The coefficient of determination ranges from 0.434 to 0.481 and the root mean square error ranges from 0.7857 to 0.8194cmyear−1. Estimated increments of 224 Douglas-fir trees in 12 different and independent stands were used to validate the model, which is expected to provide reliable predictions for most of the pure Douglas-fir stands located in the study area. [Copyright &y& Elsevier]

The reintroduction of plant species is a technique increasingly used to restore extirpated populations. Although most often used to improve the conservation status of endangered species, it can also be considered for species extinct in the wild. The process of resurrecting extinct plant species is however still in its infancy, and it entails additional challenges compared to the reintroduction of locally extinct populations. This study proposes a framework to analyse constraints to post-extinction recovery based on the case of Bromus bromoideus , a species endemic to southern Belgium and northern France, extinct in the wild since 1935. The plant still exists in ex situ collections, and seeds stored for decades at 5% moisture content and -20 °C have shown a good viability. We initiated a feasibility study to assess the risks associated to a programme aiming at reviving this long-extinct species. Several constraints were identified. Biological constraints are related to the fuzzy taxonomy of the species, the unknown origin of the seeds and undocumented ex situ cultivation, and the likely low genetic diversity of the material available for reintroduction. Ecological constraints are linked to the habitat of the species. B. bromoideus has no known natural habitat and is only found in cultivated fields, which are by definition highly anthropized unprotected areas. This study shows the importance of undertaking a preliminary study that addresses all aspects of technical feasibility, scientific justification, biological and societal risks. Based on this exercise and inspired by international standards, we developed a decision tool to assist conservationists to resurrect a plant species in the best possible way. [ABSTRACT FROM AUTHOR]

To ensure the rescue, temporary conservation and further restoration of plant populations and communities threatened by exploitation, translocation appears to be an appropriate method in the context of mining. Little is known, however, on its effect on mutualistic interactions, such as pollination, and on the resulting plant population dynamics. Whole-rock translocations were performed as a conservation strategy for the endemic metallophyte flora of Katanga, Democratic Republic of the Congo. The aim of this study was to quantify the flower visitation, sexual reproduction and ramet demographic structure in such a translocated population, and to compare the data with those from natural populations of Aeollanthus saxatilis , one of the threatened species of the chasmophytic community. The study also documented the plant's flower visitor guild. The ramet density, demographic structure, pollination success and seed abortion rate were assessed in 10 quadrats per population, in the translocated population and in two subsisting natural populations. The flower visitation rate was quantified during three observation periods (20 min each) in six quadrats per population. Small differences were observed in the visitor guild between the translocated and natural populations, but the flower visitation rate was equivalent. No clear difference in the reproductive performance or ramet demographic structure of the populations was found. The flower visitor guild was mainly composed of generalist pollinators, which probably helped in establishing a functional visitor guild at the receptor site. Rock translocation therefore appears to be an encouraging approach, allowing the conservation of functional mutualistic interactions and the maintenance of a population structure comparable to that of natural chasmophytic plant populations. [ABSTRACT FROM AUTHOR]

• Three patterns of the species response curves of the realised niches have been highilighted along macronutrient gradient. • Copper is micronutrient, Cobalt is supposed to be a beneficial element with higher toxicity than Copper. • Realised niches of 80 metallophytes along copper and cobalt have been modelled using GAMs. • Realised niches along Copper and Cobalt gradients excerpt similar pattern than common species along macronutrient gradients. • Results are encouraging for restoration purposes. Ecological niche modelling helps us to understand the spatial assembly of species in heterogeneous environments. Three patterns have been widely reported in the research literature regarding the relationship between realised niches and macronutrient concentration gradients: (1) species' optima are unevenly distributed, with a higher frequency in mesic conditions; (2) species' response curves are narrower when optima density is higher; and (3) species with optima at the extremes of the gradients have skewed response curves with a longer tail toward mesic conditions. This study aims to test the existence of these patterns on a vegetation model occurring in metalliferous soils comprising copper and cobalt along a toxicity gradient in south-eastern D.R. Congo. Realised niches of 80 taxa were modelled using generalised additive models. The niche optima and the niche widths were determined for each taxon. Results highlighted three groups which differ according to the niche optima location along the soil metal concentration gradients. The patterns found along macronutrient concentration gradients were, to some extent, transposable along micronutrient concentration gradients. Our findings on the diversity and assembly of realised niches has consequences for plant conservation strategies. [ABSTRACT FROM AUTHOR]

Seedling performance can determine the survival of a juvenile plant and impact adult plant performance. Understanding the factors that may impact seedling performance is thus critical, especially for annuals, opportunists or invasive plant species. Seedling performance can vary among mothers or populations in response to environmental conditions or under the influence of seed traits. However, very few studies have investigated seed traits variations and their consequences on seedling performance. Specifically, the following questions have been addressed by this work: 1) How the seed traits of the invasive Ambrosia artemisiifolia L. vary among mothers and populations, as well as along the latitude; 2) How do seed traits influence seedling performance; 3) Is the influence on seedlings temperature dependent. With seeds from nine Western Europe ruderal populations, seed traits that can influence seedling development were measured. The seeds were sown into growth chambers with warmer or colder temperature treatments. During seedling growth, performance-related traits were measured. A high variability in seed traits was highlighted. Variation was determined by the mother identity and population, but not latitude. Together, the temperature, population and the identity of the mother had an effect on seedling performance. Seed traits had a relative impact on seedling performance, but this did not appear to be temperature dependent. Seedling performance exhibited a strong plastic response to the temperature, was shaped by the identity of the mother and the population, and was influenced by a number of seed traits. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Substrate was determinant in the establishment of native and invasive species. • Dry grasslands species responded slowly to sowing on the tested materials. • Native cover was higher and invasive success was lower on dust material. • Dust addition is recommended given its availability and low commercial value. Abstract Habitats being restored in Belgian quarries are easily invaded by non-native plant species, which can hamper the germination and development of vegetation deemed to be of high conservation value. Substrates of terraces created when mining limestone quarries could be inhospitable to native plants. However, they can provide opportunities for establishing specific vegetation, such as dry calcareous grasslands. Applying suitable mining spoils could be a cost-effective way to provide growing substrate when restoring limestone terraces. We assessed the efficacy of using mining spoils, collected on-site, as a potential growing substrate (bedding material). We tested gravely limestone (product of on-site mining activities), limestone dust (by-product), and no addition (bare limestone bedrock) to determine which was best for favoring the growth of native, dry calcareous grassland species and discourage the growth of two non-native invasive species that commonly invade altered mining sites: Buddleja davidii Franch and Senecio inaequidens DC. In a field experiment (in two quarries), we studied short-term (2 y) growth response of native and invasive species after sowing three seed mixtures of native grassland species, varying in functional diversity (and one no-sowing control treatment), all treatments subjected to competitive pressure exerted by invasive species. Percent cover of native and invasive species, species abundance and reproductive characteristics of the invasive species were monitored during 2-y. Native grasslands coverage was low on all substrate types, demonstrating how slowly calcareous grasslands species establish in such harsh substrate conditions. However, type of substrate did show a significant relationship with plant abundance, with limestone dust being the most beneficial for native species establishment (coverage). Although limestone dust appeared to be the best option for restoring grassland species to limestone quarries (based on its low cost, wide availability, and potential to support native species), it was also likely to support the two invasive species. Functional diversity of the seed mixture had no consistent effect. Our study shows the importance of identifying the most appropriate substrate to both establish calcareous grasslands and resist invasive species. This approach provides insights into developing strategies to conserve biodiversity in industrial and agricultural landscapes with limestone quarries. [ABSTRACT FROM AUTHOR]

Intensification of agriculture has been one of the major drivers for biodiversity loss in recent decades. Pollinators, which serve an important role in pollinating crops as well as wild plants, have shown a decline in species richness. Flower strips can be used to support pollinators in agro-ecosystems, however the question remains as to how their design can be optimized in order to best benefit pollinators. Increasing plant species diversity has been shown to be beneficial for pollinators, and it is often suggested that functional traits are driving this relationship. Therefore, increasing plant functional diversity could be a tool to support pollinator abundance and diversity. As experimental evidence on this relationship is scarce, we developed a field study with experimental sown flower strips with four functional diversity levels, based on multiple flower traits and with equal plant species richness. We monitored vegetation development, as well as the flower-visiting pollinator community and their interaction networks with flowers. We were able to create a functional diversity gradient while controlling for plant species richness and evenness. However, in contrast to our expectations, pollinator species richness and evenness were not influenced by functional diversity, and increasing functional diversity even resulted in lower flower visitation rates. Network stability metrics showed no effect or negative relationships with functional diversity. We conclude that increasing functional diversity was not the key for supporting pollinators in wildflower strips. Our results also suggest that, for a constant amount of flower resources, increasing plant functional diversity and thus decreasing redundancy of potential pollinator feeding niches, decreases the amount of flower resources present per feeding niche. As pollinator species tended to have less overlap in their feeding niches in flower strips with increased functional diversity, this may lead to a reduction of flower resources available for pollinator species with a more specialized feeding niche. [ABSTRACT FROM AUTHOR]

The occurrence of an invasive plant across a continent is generally not homogeneous; typically, some areas are highly invaded whereas others show moderate or low invasion levels. This situation might be a snapshot of an ongoing spread, but it could also remain stable under the pressure of factors that constrain the invasion. Among those factors, plant performance variation among invasion levels can explain an invasion slowdown. However, few studies have investigated the large-scale variation of invasive plant performance in the field. Ambrosia artemisiifolia L. in Western Europe represents a good opportunity to address this issue, with areas of high, moderate and low invasion levels being documented across a ca. 1000 km transect. In this study, we compared in situ plant performance-related traits in 12 populations from areas of contrasting invasion levels. We also tested whether performance-related traits were influenced by the intra-and inter-specific competition, by the local climatic conditions or by latitude (a proxy for growing season length). Overall, we did not find differences in performance-related traits across invasion levels, and intra-and inter-specific competition had low effects on plant performance. This study highlights the fact that A. artemisiifolia individuals express similar performance across invasion levels, even beyond what can be considered the present invasion front. Further research has to expand this study northwards, and assess other factors that could constrain the invasion in order to highlight if the species invasion northward is constrained or if it has the potential to invade new areas. [ABSTRACT FROM AUTHOR]