Ove Eriksson

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.

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.

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.

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.

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.

We propose to consider semi-natural habitats—hotspots for biodiversity—being caught in a socio-ecological extinction vortex, similar to the phenomenon described for species threatened with extinction. These habitats are essentially socioecological systems, in which socioeconomic drivers are interlinked with ecological processes. We identify four highly interlinked and mutually reinforcing socio-economic processes, pertaining to the importance of semi-natural habitats for (i) agricultural production, (ii) policy, research and development; (iii) vocational education in the fields of agricultural sciences and (iv) public’s experiences with semi-natural habitats. Evidence from six countries in the boreal region demonstrates that recent slowing down or even reversal of two processes are insufficient to stop the extinction vortex phenomenon. We suggest research directions to ascertain the phenomenon, monitor its development and develop proactive actions to weaken the vortex. It is highly plausible that interventions directed at most, if not all, of the key vortex processes are needed to reverse the overall deteriorating trends of a socio-ecological system.

Iron production was historically associated with major impacts on forests worldwide, as vast amounts of wood were harvested to produce the charcoal needed for heating the furnaces and reducing iron oxides in the ore to iron. This impact has left abundant legacies which potentially may remain in the present‐day vegetation. We investigated how remains of historic charcoal production, mainly from the 18th to the early 20th century, at still remaining charcoal kiln platforms (CKPs), affect the current species richness, species occurrences and cover of vascular plants in the ground vegetation in a Swedish mining district located in the boreo‐nemoral forest zone. CKPs have a significantly higher species richness than the surrounding forest, and they also affect cover (negatively) for ericaceous species typically dominating the forest ground vegetation. Several forest species are more frequent at CKPs, and these also harbor significantly more uncommon species, of which many are typical for traditionally managed grasslands. These latter species are likely to represent remnants in present‐day forests reflecting former land‐use such as livestock grazing. The soil chemistry at CKPs is strongly deviating from the surrounding forest, and this, together with a lower cover of ericaceous shrubs, are the most likely mechanisms behind the higher species richness. CKPs represent conspicuous and abundant historic anthropogenic habitats in the forest vegetation. As far as we are aware, the flora at CKPs in boreal and boreo‐nemoral forests has not previously been investigated in detail, and they deserve more attention, both from a biological and a cultural–historical perspective.

Species‐rich semi‐natural grasslands are declining all over northern Europe, and many plant species confined to such grasslands are currently under threat. We studied the development of populations of one such species, the field gentian Gentianella campestris , during three decades in the County of Södermanland, south of Stockholm, Sweden. Gentianella campestris is Red Listed as Endangered in Sweden. It is a strict biennial, and as far as known with only a transient seed bank. Large population fluctuations are a characteristic of this species, and its life history makes the species inherently sensitive to factors causing population reductions. We found that the number of sites with G. campestris has declined with over 60% in the last three decades. The total number of flowering individuals also show a strong decreasing trend, although there was an increase the last year (2020) at a few remaining sites. Cessation of grazing management is a major cause of the decline, but populations also disappeared from managed sites. It is possible that the management has been inappropriate, and circumstantial evidence suggests that summer drought might be an additional cause of population decline. Data from 2018, a year with an exceptional summer drought, supports this explanation. A sowing experiment indicated that recruitment of new populations is unlikely in the present‐day landscape where most vegetation is unsuitable for G. campestris . Due to the poor prospects for long‐term maintenance of grazing management in still remaining semi‐natural grasslands, and the decline even at sites with current management, G. campestris faces a risk of becoming regionally extinct within the coming decades.