Anthropogenic biodiversity decline threatens the functioning of ecosystems and the many benefits they provide to humanity. As well as causing species losses in directly affected locations, human influence might also reduce biodiversity in relatively unmodified vegetation if far-reaching anthropogenic effects trigger local extinctions and hinder recolonization. Here we show that local plant diversity is globally negatively related to the level of anthropogenic activity in the surrounding region. Impoverishment of natural vegetation was evident only when we considered community completeness: the proportion of all suitable species in the region that are present at a site. To estimate community completeness, we compared the number of recorded species with the dark diversity—ecologically suitable species that are absent from a site but present in the surrounding region2. In the sampled regions with a minimal human footprint index, an average of 35% of suitable plant species were present locally, compared with less than 20% in highly affected regions. Besides having the potential to uncover overlooked threats to biodiversity, dark diversity also provides guidance for nature conservation. Species in the dark diversity remain regionally present, and their local populations might be restored through measures that improve connectivity between natural vegetation fragments and reduce threats to population persistence.

Context

Habitat loss and land use homogenization cause a decline in biodiversity in agricultural landscapes. Plant community in small landscape features which remain post-land use change (small natural or semi-natural habitats) may overlap with plant community in semi-natural grasslands and buffer species decline in landscapes where little or no grassland remains.

Objectives

We explored if small natural or semi-natural habitats buffer the decline of semi-natural grasslands when it comes to number of plant species with fleshy fruits and a variety of food resources for pollinators, throughout the vegetation season.

Methods

We surveyed plants in grasslands and small habitats in five agricultural landscapes; 13 semi-natural grasslands (area 7016–85547 m²), 50 forest edges (area 145–1850 m²) and 130 midfield islets (area 17–4788 m²). We than explored how the richness of plants and plant traits (fleshy fruits, flower morphology and flowering period) are related to habitat type, landscape and canopy cover in the focal habitats.

Results

Semi-natural grasslands and midfield islets had the highest richness of plant species and flower shapes compared to forest edges. In addition, midfield islets harboured more species with fleshy fruits. When comparing the plant community on midfield islets with the plant community in forest edges, midfield islets and semi-natural grasslands contributed equally with number of blooming plant species during the seasons. Landscapes that were less intensively used (less crop fields) provided food resources for a higher diversity of pollinators compares to less open landscapes, as there was a higher richness of plant species and flower morphologies. Forest edges were not as valuable to pollinators and frugivores as midfield islets.

Conclusions

Small natural or semi-natural habitats can provide food resources to pollinators and frugivores at the landscape scale in fragmented landscapes. More crop field in the landscape had a negative impact on the richness of plants and flower morphologies in the habitats. Forest borders may not be as species rich as midfield islets but are still a part of the green infrastructure in the landscape. Particularly, in intensively managed landscapes, small natural habitats can contribute to landscape plant diversity and have a complementary function to each other, but this does not fully compensate for the loss of semi-natural grasslands.

1. Wild pollinators are crucial for ecosystem functioning and human food production and often rely on floral resources provided by different (semi-) natural ecosystems for survival. Yet, the role of European forests, and especially the European forest herb layer, as a potential provider of floral resources for pollinators has scarcely been quantified.
2. In this study, we measured the potential nectar production (PNP) of the forest herb layer using resurvey data across 3326 plots in temperate forests in Europe, with an average time interval of 41 years between both surveys in order to assess (i) the importance of the forest herb layer in providing nectar for wild pollinators, (ii) the intra-annual variation of PNP, (iii) the overall change in PNP between survey periods and (iv) the change in intra-annual variation of PNP between survey periods. The PNP estimates nectar availability based on the relative cover of different plant species in the forest herb layer. Although PNP overestimates actual nectar production, relative differences amongst plots provide a valid and informative way to analyse differences across time and space.
3. Our results show that the forest herb layer has a large potential for providing nectar for wild pollinator communities, which is greatest in spring, with an average PNP of almost 16 g sugar/m²/year. However, this potential has drastically declined (mean plot-level decline >24%).
4. Change in light availability, associated with shifts in canopy structure and canopy composition, is the key driver of temporal PNP changes.
5. Synthesis. Our study shows that if management activities are carefully planned to sustain nectar-producing plant species for wild pollinators, European forest herb layers and European forests as a whole can play key roles in sustaining wild pollinator populations.

This study explores how resource colonization for iron in central Sweden during the early Iron Age may have affected the use of forest landscapes. Slag heap volume at iron production sites was used to estimate the amount of forest resources required for charcoal production. Forest resources required for livestock grazing and fodder were estimated from literature sources. To produce charcoal at iron production sites, forests were harvested, creating conditions suitable for grazing. Production of livestock winter fodder, leaf-hay, became a constraint due to the conflict between grazing grounds and fodder producing areas near main settlements. Although availability of forest was not limiting, a combination of opportunities and constraints is suggested to have promoted a new spatial ordering of land use. This included land closest to the main settlements allocated to fodder production and development of secondary seasonal settlements (shielings) at iron production sites, which could be exploited for livestock grazing. 

In insect-pollinated, bird-dispersed plants, both investment in reproduction and reproductive success involve interactions between plants and their pollinators and dispersers. The outcome of these plant–animal interactions may be affected by the number of flowers and fruits, as well as by the plants' local environment and by spatial associations among plants. In this study we mapped the spatial distribution of individuals in a population of the early flowering, fleshy-fruited shrub Daphne mezereum, in a forest in boreo-nemoral Sweden. For all mapped individuals we collected data on numbers of flowers and fruits and fruit removal, for three consecutive years. We analysed spatial associations among individuals, and the effects on reproductive performance and fruit removal of plant height, numbers of flowers and fruits, distance to forest edge, and neighbouring flower and fruit density. Our results show that the density of D. mezereum increases with increasing proximity to forest edge. The number of flowers produced, as well as fruit set and fruit removal, show the same positive relationship with increasing proximity to forest edges. We further show that individuals are aggregated up to distances of about 10 m. The flower production of neighbouring conspecific individuals within 10 m is negatively related to fruit set whereas the fruit production of neighbours is positively related to fruit removal. Our main conclusion is that the spatial distribution of D. mezereum affects reproductive success and fruit removal, which in turn has the potential to feed back to the spatial distribution pattern. Combining studies of reproduction with spatial analyses is important to advance our understanding of the dynamics of plant populations. 

Although often overlooked, the Danish botanist Eugen Warming was one the founders of ecology as a science. He also wrote extensively on plant life forms, including an essay from 1918, Om Jordudløbere (‘Underground runners'), which specifically focused on clonal plants. As was common among naturalists during the 19th century, Warming was exceptionally skillful in drawing conclusions from plain observation. The present paper examines how Warming understood and interpreted the ecology and evolution of clonal plants, and compares his insights with those emanating during the revival of research on clonal plants from the late 1970s onward. Several of the key topics in this revival were treated already by Warming, particularly clonal plants' ability of mobility by horizontal growth, the features affecting the ‘splitting' of genets into independent ramets, and how clonal life forms evolve. Despite these thematic similarities, Warming's direct impact on later research was limited, with the possible exception of the concept of plant functional types. This does not preclude that Warming's insights have bearing on the current research agenda on the ecology and evolution of clonal plants. The paper ends with a brief discussion of horizontal growth as a means to extend genet lifespan, thereby providing a basis for evolution of clonal plant life form through processes acting within genets. 

The Crafoord Prize is awarded in partnership between the Royal Swedish Academy of Sciences and the Crafoord Foundation in Lund. The Academy is responsible for selecting the Crafoord Laureates.

This year, the Crafoord Prize in Biosciences is awarded to the Canadian evolutionary biologist Dolph Schluter (Fig. 1) for fundamental contributions to the understanding of adaptive radiation and ecological speciation. Schluter now joins the line of prominent earlier Crafoord Laureates in Biosciences, which includes, for example, Edward O. Wilson, William Hamilton, Robert May, John Maynard Smith, Ernst Mayr, George Williams, Robert Trivers, Ilkka Hanski, Tomoko Ohta, Richard Lewontin and, most recently (2019), Sallie Chisholm.

Livestock has been a backbone of people's livelihood as long as agriculture has existed in Scandinavia, c. 6,000 years. In the early Iron Age, c. 2,000 years ago, a land management system began to form, composed of infields (enclosed hay-meadows and crop fields) and outlying land used for livestock grazing. Despite many later innovations and societal changes affecting agricultural technology and practices, this way of organizing land use was a template for how landscapes were managed and structured until the modernization of agriculture and forestry during the last centuries. There are legacies of this historic land-use, mainly as semi-natural grasslands managed by livestock grazing (open or semi-open; long continuity of management; not much influenced by commercial fertilizers, plowing etc.). These semi-natural grasslands harbor an exceptional small-scale biodiversity, particularly plants and insects. Landscapes with semi-natural grasslands represent cultural heritage, and are appreciated for their beauty. The total area of semi-natural grasslands has declined considerably during the past 100 years, and the current trend suggest that further declines are expected. A large fraction of threatened biodiversity in Sweden thrives in these grasslands. Livestock grazing in semi-natural grasslands makes an important contribution to food production, and there is an increasing interest in consumption of products, mainly meat, from these grasslands. This implies that there is a positive feedback between food production, maintenance of biological diversity, and cultural heritage. This paper gives an overview of semi-natural grasslands, focusing on Sweden, from a historic, cultural and ecological perspective, and aims at discussing challenges and prospects for developing and maintaining positive associations between producing food, biodiversity, and cultural heritage, in the future.

Species turnover is ubiquitous. However, it remains unknown whether certain types of species are consistently gained or lost across different habitats. Here, we analysed the trajectories of 1827 plant species over time intervals of up to 78 years at 141 sites across mountain summits, forests, and lowland grasslands in Europe. We found, albeit with relatively small effect sizes, displacements of smaller- by larger-ranged species across habitats. Communities shifted in parallel towards more nutrient-demanding species, with species from nutrient-rich habitats having larger ranges. Because these species are typically strong competitors, declines of smaller-ranged species could reflect not only abiotic drivers of global change, but also biotic pressure from increased competition. The ubiquitous component of turnover based on species range size we found here may partially reconcile findings of no net loss in local diversity with global species loss, and link community-scale turnover to macroecological processes such as biotic homogenisation. 

Many forests throughout the world contain legacies of former human impacts and management. This study reviews evidence of floristic legacies in the understory of Swedish boreo-nemoral forests, and presents a case study on two currently declining forest plants, suggested to have been favored by historical use of forests. The review provides evidence of forest remnant populations of 34 grassland species. Thus, many floristic legacies have their main occurrence in semi-natural grasslands, but maintain remnant populations in forests, in some cases more than 100 years after grazing and mowing management have ceased. Despite less information on true forest understory plants appearing as legacies of historical human use of boreo-nemoral forests, a putative guild of such species is suggested. The case study on two species, Chimaphila umbellata and Moneses uniflora (Pyroleae, Ericaceae) suggests that both species are currently declining, mainly due to modern forestry and ceased livestock grazing in forests. Chimaphila maintains remnant populations during decades, due to its extensive clonal capacity and its long-lived ramets. Moneses is more sensitive, due to a lower stature, weaker clonal capacity and short-lived ramets, flowering only once during their lifetime. Thus, Moneses have more transient occurrences, and will decline rapidly under deteriorating conditions.