• Publications connexes au projet

    Douze publications en lien avec le projet smallFOREST ont été publiées entre 2013 et 2017 :

    * Molecular identification of novel phlebovirus sequences in European ticks.
    Prinz, M., Fuchs, J., Ehrmann, S., Scherer-Lorenzen, M., Kochs, G., Panning, M.
    Ticks and Tick-Borne Diseases 8, 795-798 / DOI :

    Abstract : In recent years the number of newly described tick-borne phleboviruses has been steadily growing. Some of these novel viruses are highly pathogenic in humans, e.g. the Heartland and severe fever with thrombocytopenia syndrome virus. We aimed to analyse ticks sampled across Europe to investigate the diversity of phleboviruses using a comprehensive PCR-based screening approach. A total of 4387 ticks were collected from the vegetation in regions of France, Belgium, Germany, Sweden, and Estonia, respectively. Ticks were pooled and 22/979 pools tested positive using a PCR targeting the large (L) segment of phleboviruses. Phylogenetic analysis of a 500-bp fragment of the L segment showed a distinct novel clade provisionally named Glabbeek/Osterholz group (Belgium and Germany). In addition, sequences from ticks sampled in France clustered together with the recently described Antigone virus from Greece and AnLuc from Portugal. Our results extend the current diversity of phleboviruses in Europe. Future research should address the ecological processes driving the occurrence of phleboviruses and the impact of these novel phleboviruses for public health.


    * Community response to alkaline pollution as an adjusting re-assembly between alternative stable states
    Suija, A.; Liira, J.
    Journal of Vegetation Science, 28 (3), 527−537.10.1111/jvs.12506 / DOI :

    Abstract :
    We hypothesize that the community response to disturbances can be interpreted as a large-scale dynamic equilibrium between multiple alternate states stemming from different species pools within a regional meta-pool and being limited by species’ multi-dimensional niches. We explore this hypothesis by examining the re-assembly of an acidophilous lichen community in response to long-term alkaline dust pollution, assuming understorey as a potential side-factor.
    Around a cement factory in Kunda, Estonia.
    Lichen communities on Scots pine (Pinus sylvestris) trunks in 40 stands around a cement factory and in nine distant limestone habitats were assessed.
    The formed bark pH gradient from pH 2.4 to 8.1 was reflected in a continuum of lichen communities on pines from acidophilous to basidophilous communities. Besides suppressing species richness, understorey density more evidently caused the compositional divergence from neutral bark conditions. The effect of hidden interactions among drivers was explained through reactions of individual species – almost all species across the pollution gradient were pH-limited, whereas species adapted to neutral or alkaline substrate were additionally sensitive to understorey conditions. The hump-shaped distribution of pH niche ranges along the observed niche optima, rather than ecological indicator values, showed that the shape of species’ multi-dimensional niche-space still needs to be quantified.
    Each alternative community state along the disturbance gradient represents a realization of its specific species pool within the meta-pool. Degradation can be defined if the community state is not supported by a meta-pool. Species infiltration during community re-assembly can be predicted using species source communities as cost-efficient proxies.


    * Both spatiotemporal connectivity and habitat quality limit the immigration of forest plants into wooded corridors
    Paal, T.; Kütt, L.; Lõhmus, K.; Liira, J.
    Plant Ecology, 218 (4), 417−431.10.1007/s11258-017-0700-7 / DOI :

    Abstract : Extensive afforestation of agricultural areas has increased the importance of green corridors as a dispersal network. We tested the effect of spatiotemporal connectivity, edge effect and habitat structural quality of wooded corridors on the long-term immigration success of forest specialist plants relative to the performance of forest generalists. In agricultural landscapes of central and southern Estonia, we sampled 28 historically connected and 52 isolated tree lines and alleys with a minimum age of 50 years, and 93 edges of ancient forests. The regional pool of common forest plants was compiled using species’ frequency data in 91 ancient forests. Both landscape connectivity and habitat quality affected the richness of response groups, but specialists and generalists responded to different drivers. Forest specialists required long-term neighbourhoods of ancient forest and benefited from a direct connection between forest and corridor. Habitat generalists reacted positively to the recently modified structure of the landscape. When a corridor was connected to forest, the dual edge in the corridor did not result in an increased negative edge effect on forest specialist arrival. Even if both specialists and generalists required wide corridors with optimum shade, forest specialists also benefited from mature overstorey and outward overhanging branches, whereas forest generalists used disturbance-created microhabitats. We conclude that only wooded corridors with long-term connectivity to seed source forests and widely branched tree canopies will function as a green infrastructure supporting forest-specific biodiversity.


    * Multi-scale ecology of insectivorous bats in agricultural landscapes
    Kalda, O.; Kalda, R.; Liira, J.
    Agriculture, Ecosystems & Environment: 199: 105–113 / DOI :

    Abstract : During the last century, agricultural landscapes have gone through a process of homogenization, driven by the intensification of land use. Homogenization has led to a decline in biodiversity and a degradation of ecosystem services; for instance, biological pest control. Bats have been fairly invisible service providers and the effect of landscape structural changes on them is poorly understood.
    We assessed the relative roles of woody habitats and the composition of agricultural landscapes on the diversity and activity of bats in southern Estonia. The study applied a stratified double-point sampling scheme in 30 rural landscape windows comprised of three habitat types, where bats were recorded using automated recording devices. The structure of each stand was described, and the typology of solitary trees, linear objects (alleys and tree-lines) and woodland patches was transformed into a continuous gradient of tree density to simplify the extrapolation of results.
    Among 10 species and the Myotis brandtii/mystacinus complex, Eptesicus nilssonii and Pipistrellus nathusii prevailed. Species richness and the flight activity of bats were the highest in woodlands, as expected. Linear corridors and solitary trees shared relatively equal richness, while flight activity was three times higher around double-tree-lines (alleys) than around single-tree-lines and solitary trees. Such a pattern was log-linearly related to tree density. Large-scale factors, such as landscape structure and the local species pool, were important drivers for both response indicators; flight activity was additionally dictated by a stand’s vertical structure.
    We conclude that in order to promote bat diversity and the service potentially provided to agriculture, future agri-environmental schemes should incorporate multi-scale management planning: (i) coordinated establishment or maintenance of alleys and small woodland patches within field complexes over neighbouring farms in the scale of several kilometres; (ii) forming water bodies in the vicinity of woody habitats to improve the landscape quality for bats; and (iii) paying special attention on the preservation of old and low branching trees in each woody habitat type.


    * Multi-scale ecology of woodland bat the role of species pool, landscape complexity and stand structure
    Kalda R; Kalda, O; Lõhmus K; Liira J.
    Biodiversity and Conservation 24: 337-353 / DOI :

    Abstract : Fragmentation of forest landscapes and structural degradation of woodlands have a holistic negative effect on biodiversity. Bats are considered as indicators of woodland’s structural quality. However, as bats commute long distances on a nightly basis, their diversity should also be limited by large-scale drivers such as landscape and species availability in the region. Therefore we examined roles of the local species pool, landscape structure and habitat properties on species richness of bats through three spatial scales with emphasis on top–down relationships. Our aim for conservation ecology was to evaluate habitat quality and the importance of stand origin, i.e. contrast between mature forests and old parks. Bats were surveyed in 28 landscape windows, which consisted of at least one park and forest site. In total we sampled 63 deciduous woodlands in Estonia. In each site we sampled two microhabitats: edge and stand interior. Bat species richness was mostly explained by large-scale drivers, such as local species pool and landscape composition within 1 km radius. Stand properties had a weaker effect, driven by understory clutter. At the finest scale, the importance of edge habitats was emphasized by greater species richness at the edge in comparison to the stand interior and the edge’s predictive power on species richness in the stand interior. Habitat origin (park vs. forest) was an important aspect only for small-scale species richness, specifically in woodland interiors. The conservation policy of woodland bats should be based on complex multi-scale planning, in which natural and anthropogenic woodlands can be considered as a single land-cover type. To provide optimal foraging habitat for bats, the forest landscape should be diversified with integrated small waterbodies and canopy gaps with sharp edges.


    * Platybunus pinetorum (Arachnida, Opiliones) new to Sweden
    Fritzén N.R., Rinne V., Sunhede M., Uddström A., Van de Poel S., De Smedt P.
      Memoranda Soc. Fauna Flora Fennica 91: 37-40 /

    Abstract : In 2013 and 2015 several specimens of the opilionid Platybunus pinetorum (C.L. Koch, 1839) were found in Sweden in two different places almost 500 kilometers from each other. The species was not previously known in the country. The discovery initiated a survey of specimens reported as Rilaena triangularis (Herbst, 1799) on two Swedish web pages, in search for misidentified P. pinetorum. A further three specimens of the new species were found, indicating that it is already rather widespread in southern Sweden.


    * Do forest plants conform to the theory of island biogeography: the case study of bog islands
    Liira, J.; Jürjendal, I.; Paal, J.
    Biodiversity and Conservation, 23: 1019 – 1039 / DOI :

    Abstract : Biodiversity conservation is confronted with increasing risk of extinction in isolated small-area remnants and the limitation of species to colonize recently formed habitats. We hypothesized that the equilibrium pattern of forest herb layer in long-term fragmented landscape should comply with the theory of island biogeography. Forests on mineral soil islands located in large mires of western Estonia were considered as dispersal target habitats, and forests on mainland and peninsulas in mires as sources. Species richness was the lowest in mainland forests and the effect was confounded by habitat structure, suggesting a negative effect of silvicultural management in easily accessible forests. We observed the ‘small island effect’, i.e. greater overall species richness in small-area habitats, which was determined by the habitat preference of shade tolerant generalists. The average species richness of common mainland forest specialists varied little, but capitalizing on the traditional approach and analyzing only island data, weak effects of distance and habitat quality were detected. At single species level, unexpectedly, many habitat specialists were observed to have successfully dispersed to islands, indicating insufficient knowledge of the long-distance dispersal mechanisms of forest-dwelling plants. In fragmented forest landscapes the theory of island biogeography can be applied to habitat specialist plant species, but only regarding the effect of isolation and in conditions of persistent forest structural quality. In the light of global changes, optimized conservation planning should primarily target on (i) the conservation of ancient habitat fragments independent of their current area, and (ii) the promotion of diversity of potential dispersal vectors in the landscape.


    * Long-term colonization ecology of forest-dwelling species in a fragmented rural landscape – dispersal versus establishment
    Lõhmus, K.; Paal, T.; Liira, J.
    Ecology and Evolution 4: 3113 – 3126 / DOI :

    Abstract : Species colonization in a new habitat patch is an efficiency indicator of biodiversity conservation. Colonization is a two-step process of dispersal and establishment, characterized by the compatibility of plant traits with landscape structure and habitat conditions. Therefore, ecological trait profiling of specialist species is initially required to estimate the relative importance of colonization filters. Old planted parks best satisfy the criteria of a newly created and structurally matured habitat for forest-dwelling plant species. We sampled species in 230 ancient deciduous forests (source habitat), 74 closed-canopy manor parks (target habitats), 151 linear wooded habitats (landscape corridors), and 97 open habitats (isolating matrix) in Estonia. We defined two species groups of interest: forest (107 species) and corridor specialists (53 species). An extra group of open habitat specialists was extracted for trait scaling. Differing from expectations, forest specialists have high plasticity in reproduction mechanisms: smaller seeds, larger dispersules, complementary selfing ability, and diversity of dispersal vectors. Forest specialists are shorter, less nutrient-demanding and mycorrhizal-dependent, stress-tolerant disturbance-sensitive competitors, while corridor specialists are large-seeded disturbance-tolerant competitors. About 40% of species from local species pools have immigrated into parks. The historic forest area, establishment-related traits, and stand quality enhance the colonization of forest specialists. The openness of landscape and mowing in the park facilitate corridor specialists. Species traits in parks vary between a forest and corridor specialist, except for earlier flowering and larger propagules. Forest species are not dispersal limited, but they continue to be limited by habitat properties even in the long term. Therefore, the shady parts of historic parks should be appreciated as important forest biodiversity-enhancing landscape structures. The habitat quality of secondary stands can be improved by nurturing a heterogeneous shrub and tree layer, and modest herb layer management.


     * Plant species richness of very small forests related to patch configuration, quality, heterogeneity and history
    Wulf, M. & Kolk, J.
    Journal of Vegetation Science 26, 1267-1277/ DOI : 10.1111/jvs.12172

    Abstract :
    (i) Is plant species richness related to patch configuration, quality, heterogeneity and history in very small forest patches? (ii) Is there a similar effect of patch configuration, quality, heterogeneity and history on all plant species or does it vary for different plant groups? (iii) Does the importance of patch configuration, quality, heterogeneity and history vary for plant species richness between patch size classes?
    Prignitz region, western part of Brandenburg, Germany
    Plant species lists for 183 forest patches (0.08–12.7 ha) were compiled. We conducted a hierarchical partitioning analysis to test which of the four patch variables – configuration, quality, heterogeneity and history – explained most of the variance in plant species richness and richness of various plant groups.
    Irrespective of patch size class, species richness is mainly predicted by patch quality and heterogeneity. In particular, generalists are primarily affected by the soil moisture and nutrient level, and specialists additionally by patch heterogeneity and history. A higher historical habitat quality, together with long habitat continuity, led to an increase in forest specialists and geophytes in all patches. In the >5-ha patches only historical habitat quality accounted for a significant increase in the number of species with short-distance dispersal capacity in all species. Regardless of patch size, the number of locally infrequent species increased significantly with historical habitat quality. The effect of patch configuration was negligible, except for space-filling trees and shrubs, when considering all patches.
    Our more comprehensive statistical approach shows, in general, that all complex variables have an effect on species richness and should be considered in future studies. The fact that patch heterogeneity and quality are the main predictors of species richness indicates that very small forest patches covered a range of highly structured patches and sites having various growth conditions. We assume that the century-old tradition of private ownership with smallholder social structure is the main reason for variability in stand structure and species assemblage, resulting in the uniqueness of each patch. Since the number of locally infrequent plant species increases significantly with historical habitat quality, we suggest that it is particularly important to consider this variable in future studies on the decline of infrequent plant species.


    * Do forest-dwelling plant species disperse along landscape corridors?
    Liira, J.; Paal, T.
    Plant Ecology 214: 455−470 /
    DOI : 10.1007/s11258-013-0182-1

    Abstract : Woody corridors in fragmented  land- scapes have been proposed as alternative habitats for forest plants, but the great variation in species-specific responses blurs the overall assessment. The aim of this study was to estimate the dispersal success of forest- dwelling plants from a stand into and along an attached woody corridor, and to explain the observed patterns from the point of view of species’ dispersal traits and corridor properties. We sampled 47 forest–corridor transects in the agricultural landscapes of southeastern Estonia. Regionally common forest-dwelling species (observed in at least 10 % of seed-source forests) were classified on the basis of their ecological response profile—forest-restricted species (F-type) and forest- dwelling generalists (G-type). Species richness and the proportion of F-type species decreased sharply from the seed-source forest core to the forest edge and to the first 10–15 m of the corridor, while G-type species richness remained constant throughout the transect. Corridor structure had a species-specific effect—F species were promoted by old (C50 years) and wide (C10 m) corridors, while G species were supported by young and narrow corridors with ditch- related soil disturbances. Moderate shade (canopy cover <75 %) was optimal for all forest-dwelling species. Large dispersule weight, and not seed weight, dispersal vector or Ellenberg’s indicator values, was the trait that differentiated F species from G species. We conclude that most woody corridors are only dispersal stepping-stone habitats for habitat generalist species, and not for specialists. Only century old corridors can relieve the dispersal limitation of forest- restricted species.


    * Old rural parks support higher biodiversity than forest remnants 
    Lõhmus, K.; Liira, J.
    Basic and Applied Ecology 14: 165−173 / DOI :

    Abstract : One of the main challenges in biodiversity conservation is to curb a further degradation and loss of high-quality habitats. In agricultural matrix landscapes, the detection of alternative habitats for habitat specialists may be a solution. Historic old parks or landscape gardens around manor houses and castles are cultural heritage of nobles, but their value in harbouring biodiversity is poorly acknowledged. Therefore we evaluated the potential of old rural parks to serve as a habitat for nemoral forest species. We recorded stand structure and the presence of forest biodiversity indicators in 74 closed-canopy stands of historic parks and compared them with 93 neighbouring mature forest remnants on ancient forest land. We estimated the importance of stand structure in relation to habitat type on biodiversity indicators. Finally we suggest single-value indicator-complexes for the cost-efficient assessment of the conservation value of forests and forest-like habitats. Park stands outclassed reference forests in several individual structural characteristics, and in combined indicators of habitat quality and biodiversity. Forests had higher estimates for the combined indicator of dead wood, but large-diameter dead wood types were more abundant in parks. Woodpeckers, several old-growth indicator epiphytes and forest herbs had successfully become established in planted forest-like park fragments. Old rural parks resemble high-conservation-value forests more than the best preserved contemporary forest remnants. After the century needed to overcome immigration delay, old parks do provide a refugium for temperate deciduous forest species. Consequently, biodiversity-targeted management should retain and enhance old-growth attributes in forests and on the peripheries of parks: e.g. preserving old trees to provide service for epiphytes, hollow trees and an understorey mosaic for birds and bats; dead wood elements for saproxylic insects and fungi; limited mowing frequency and increased cutting height for forest herbs. Forestry should enhance the recovery of mixed deciduous stands and avoid conifer plantations.


     * Biodiversity composition reflects the history of ancient semi-natural woodland and forest habitats – Compilation of an indicator complex for restoration practice
    Palo, A.; Ivask, M.; Liira, J.
    Ecological Indicators 34: 336−344 /
    DOI : 10.1016/j.ecolind.2013.05.020

    Abstract : For centuries, Fennoscandian wooded meadows and woodland pastures (Habitats Directive habitat types *6530 and 9070 respectively) covered large areas of Northern Europe. In the Twentieth Century, abandonment-driven encroachment has led to the wooded grasslands changing into what may be considered as old-growth deciduous forests. The present paper examined whether the present stand structure and the composition of three contrasting functional groups (herbaceous layer vascular plants, epiphytic bryophytes, and earthworms) could serve as indicators of the historic origin of the forest patches, i.e. to what extent changes in ecological conditions in overgrown woodlands have shifted towards broad-leaved forests with ancient trees. Indicators were tested for the objective of restoration planning of habitat quality, i.e. whether semi-open woodlands could be restored or if it would be more appropriate to preserve them as broad-leaved forests. The study was carried out by comparing the composition of ancient forest cores, forest edges and overgrown wooded grasslands. The land use history of sample sites was examined from historical topographical maps and aerial photos.

    The results showed that as long as 60 years after abandonment, parts of the studied forests still retained some light-demanding plant species characteristic of historical wooded grasslands. The composition of earthworm communities was similar in all of the studied historical forest groups. Only some of the stand structure characteristics and epiphytic mosses indicated that there were differences between ancient forest cores and overgrown wooded grasslands. We conclude that the combination of various functional indicators should be used in the evaluation of successional woodlands for habitat restoration.




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