Diaspore Dispersal Research Articles

Topsoil disturbance reshapes diaspore interactions with ground‐foraging animals in a megadiverse grassland

AbstractQuestionsAnthropogenic disturbances are known to be followed by extremely poor recovery in edaphic grasslands. However, the role of interactions with diaspore predators and secondary dispersers, which compose the dispersal filter and modulate plant community recovery, has been overlooked. We performed field experiments to investigate how soil disturbances affect diaspore interactions with the ground‐foraging fauna to better understand how disturbance influences regeneration potential.LocationCampo rupestre vegetation, megadiverse edaphic grasslands, southeastern Brazil.MethodsWe used diaspores from five native species to compare removal rates between disturbed (top soil removal) and preserved sites; we also controlled invertebrate and vertebrate access to determine their role. In addition, we assessed differences in the diaspore removal effectiveness (DRE) and the structure of animal–diaspore interactions through network based‐approach.ResultsFor three species, the average diaspore removal rates was relatively high (between 30% and 70%). Invertebrates were the most common removal agents in both disturbed and preserved sites. Interactions with foraging fauna and removal rates were 20% smaller in disturbed sites. Considering all diaspore removal events in disturbed sites, 24% resulted in the displacement from disturbed to preserved sites, but no diaspore was transported from preserved to disturbed ones. The animal–diaspore network was exclusively composed by ant–diaspore interactions and was more diverse and robust in preserved sites compared with disturbed ones. Seed predator ants (Pheidole and Dorymyrmex) were more common in disturbed sites. Furthermore, significant differences were found in the DRE between ant species and site types, suggesting specificity in the provision of dispersal services.ConclusionsTopsoil removal affected removal proportions, DRE and ant–diaspore interaction network structure. The lack of diaspore dispersal towards disturbed sites indicates that soil removal affects secondary seed removal dynamics, impeding recovery potential. Disturbance negatively affected diaspore fate by reshaping interactions with ground‐foraging secondary seed dispersers and predators, constraining the development of seed bank and thus impacting upon vegetation dynamics and resilience.

Vulnerability to Copper Smelter Emissions in Species of the Herb–Dwarf Shrub Layer: Role of Differences in the Type of Diaspore Dispersal

The type of diaspore dispersal may have a significant effect on the vulnerability of herbaceous plants to anthropogenic transformation of ecosystems. However, there is still no unified opinion on the relationship between the type of diaspore dispersal and the processes of extinction and colonization. Here, descriptions of vegetation performed in the zone of impact from the Middle Ural Copper Smelter in the periods of high and low emission levels (1995–1998 and 2014–2016, respectively) have been analyzed to test two hypotheses: (1) the type of diaspore dispersal has an effect on plant vulnerability, with the species whose diaspores are dispersed farther being less vulnerable to habitat transformation; and (2) irrespective of the type of dispersal, recolonization is less intense under high than under low pollution levels. It has been found that the species richness of all plant groups highly varies in space: it decreases sharply in the zone of heavy toxic loads, but localities with high species richness occur even under conditions of heavy pollution. With the increasing pollution level, the species diversity within plant groups on a mesoscale (hundreds of meters) decreases more strongly than that on a macroscale (kilometers). Species with different types of diaspore dispersal differ from each other both in sensitivity to pollution and in the capacity for recolonization after reduction of emissions, but the relationship between vulnerability and the distance of diaspore dispersal is ambiguous. High sensitivity to pollution and low recolonization capacity have been revealed in species characterized by either the lowest (autochores) or the highest dispersal distance (epi- and endozoochores), with anemochores being the least vulnerable. The diversity of most groups in the zone of heavy pollution has remained low over the past 20 years; some positive shifts have occurred in myrmecochores and typical anemochores, with the dynamics of the latter being independent of pollution level.

Dispersal of a forest liana into grasslands and post-establishment stand expansion

Encroachment into the moist coastal grasslands within eThekwini Municipality by Dalbergia obovata, an indigenous forest liana that forms dense monospecific stands, poses a potential biodiversity threat. Identification of the mechanisms of D. obovata diaspore dispersal from neighbouring adjacent forests, and subsequent patterns of propagation within the grasslands, was required to understand how D. obovata encroached into the grasslands. A simple wind dispersal model for D. obovata diaspores was developed to determine potential dispersal distances under different wind conditions. Field surveys were undertaken to map the distribution of plants within stands of D. obovata in the grasslands of two urban nature reserves and these were compared against historic orthophoto records to determine when establishment occurred. Stands were excavated to investigate the primary method of propagation by D. obovata once it had become established. The results of the wind dispersal modelling and field surveys showed that D. obovata dispersal was a product of the height of diaspore release and wind velocity. For successful dispersal to occur, diaspores would have to occupy positions close to the forest margin. Successful establishment of D. obovata was infrequent, and likely associated with extreme weather events, but once established, clonal propagation via roots and lateral branches resulted in expansion of the stands. The progressive expansion of the stands in the grasslands represents a threat to the grasslands.

Wind-Generated Seed Shadow in Southern Brazil: The Influence of the Mother Plant and Wind Direction

Abstract Diaspore dispersal is an essential function of plant species, with effects on plant populations and natural forest dynamics. This study examines how traits of the mother plant (height, crown spread and distance from the diaspores) and the wind (wind speed) affect the spatial distribution of anemochorous diaspores of Apuleia leiocarpa, Peltophorum dubium, and Jacaranda micrantha in Southern Brazil. The number of diaspores from A. leiocarpa, P. dubium, and J. micrantha decrease with the increase in distance from the mother plant and there was no influence of wind direction on the spatial distribution of diaspores. Diaspore sizes of these plants were not related to their dispersal distances. Diaspore dispersal for A. leiocarpa was negatively correlated to the plant height and the crown spread. The dispersal of Peltophorum dubium and Jacaranda micrantha were not influenced by the diaspores and plants traits considered in this study.

Responses of secondary wind dispersal to environmental characteristics and diaspore morphology of seven Calligonum species

AbstractSecondary diaspore dispersal by wind, that is, wind‐driven movement along the ground surface (GS), is important for the structure and dynamics of plant populations and communities. However, how wind velocity (WV), GS, and diaspore morphology influence diaspore secondary dispersal by wind are unclear. We used a wind tunnel and video camera to measure the threshold of WV (TWV) and diaspore velocities (DV) of secondary diaspore dispersal. Diaspores of seven Calligonum species with different appendages (wings, bristles, membranous balloon, and wings + thorns) were used to determine the TWV and DV under variable wind speed (4, 6, 8, and 10 m s‐1) and four GSs (cement, sand, loam, and gravel). GS and diaspore morphological traits explained 37.1 and 18% of diaspore TWV, respectively. Meanwhile, WV, GS, and diaspore morphological traits explained 62.4, 13.6, and 3.2% of DV, respectively. An increasing trend was shown for TWV, and a decreasing trend was shown for DV in the order of cement, sand, loam, and gravel surfaces. Spherical and light diaspores had low TWV and high DV, whereas winged and heavy diaspores had high TWV and low DV. Our results indicated that adaptive features of diaspore appendages might be the result of selection for primary dispersal or secondary dispersal. The mechanism of diaspore secondary dispersal is important for understanding the recovery of degraded sand dunes and providing theoretical support for restoration practices.

Maarja Öpik

Maarja Öpik

Dandelion diaspore dispersal: frictional anisotropy of cypselae of Taraxacum officinale enhances their interlocking with the soil

We analysed the surface anisotropy of Taraxacum officinale cypselae, without their pappus, microscopically and biomechanically. A scanning electron microscope was used for visual analyses. We then measured the angle, at which cypselae start to slide from tilted substrates of different roughness and compared cypselae sliding along their structure with those sliding against their structure. Finally, forces during pushing cypselae into the soil and pulling them out were measured with a force transducer moved by a micromanipulator. The cypselae had a ribbed surface pattern with apically pointing spines, plenty of scale-like structures and small protuberances. In general, the angle at which cypselae started to slide-off from an inclined surface increased with increasing roughness of the inclined surface, but this did not hold for cypselae sliding along their structure and for the glass surface. The angles at which the cypselae started to slide were on all but the glass surface significantly higher for cypselae sliding against the structure compared to cypselae sliding along the structure. Pull-out forces were higher when pulling cypselae out of the soil against their structure compared to pulling along their structure. Anisotropic structures hinder cypselae from being drawn from soil by wind.

First evidence for the joint dispersal of mycorrhizal fungi and plant diaspores by birds.

Seed dispersal allows plants to colonise new sites and escape from pathogens and intraspecific competition, maintaining plant genetic diversity and regulating plant distribution. Conversely, most plant species form mutualistic associations with arbuscular mycorrhizal (AM) fungi in a symbiosis established immediately after seed germination. Because AM fungi are obligate symbionts, using the same dispersal vector as their host should be highly advantageous for their survival, but the co-dispersal of seeds and AM fungal spores has never been confirmed. We aim to clarify the potential role of European birds, essential dispersers for many plant species, as co-dispersers of seeds and AM fungal spores. In total, 63 bird droppings with intact seeds were placed in sterilised soil and maintained for 4months in a protected environment to avoid contamination. Additionally, 173 bird droppings and 729 gauze swabs used to clean birds' feet were inspected for AM fungal spores. Although no spores were detected by direct observation of these samples, seven Rubus ulmifolius seedlings obtained from four independent droppings of Erithacus rubecula and Sylvia melanocephala were colonised by AM fungi. Our results show that birds can effectively co-disperse viable seeds and AM fungal spores, potentially over long distances, providing a pivotal mechanism to understand the cosmopolitan distribution of AM fungi.

An awn typology for Australian native grasses (Poaceae)

Australia has a large diversity of native grasses. The diaspores of many species possess awns that vary considerably in their number and shape. Some variations of awn shape have been found to be effective at diaspore dispersal. Although morphological descriptions of awns exist for most native grass species, the number of species that possess awns and the extent of awn variation is unknown. This makes it difficult to determine the evolutionary importance of awns and the potential function of the various morphologies. The aim of this study was to construct an awn typology based on morphological descriptions collated from published flora databases that will quantify the awn type diversity of all native grass species in Australia, and will inform awn type relationships and help to clarify the role of differing awn morphologies in diaspore dispersal. We found that 42.1% of 1000 Australian native grasses with a single awn type were determined to have a ‘significant’ awn. These could be classified into one of 20 awn types, the most common being (1) single, apical, geniculate (once-sharply bent) awns (93 species; 28 genera, especially Iseilema), (2) three, apically-attached, straight awns (59 species, mainly Aristida) and (3) single, apical, bigeniculate (twice-sharply bent) awns (46 species, mainly Austrostipa). Among Australian grasses, slightly (though significantly) more C3 species (49.2%) had awns than C4 species (39.9%), although the most common awn types in both contained sharply bent awns (bigeniculate and geniculate respectively). Our classification system will help to improve our understanding of the amount of awn morphological variation in Australian grasses and will enable further investigation into the important ecological role of awns in species fitness.

Distribution of Plant Species and Dispersal Traits along Environmental Gradients in Central Mediterranean Summits

High-mountain ecosystems are spots of plant diversity in which species composition and traits depict a long evolutionary history of species adaptation to steep environmental gradients. We investigated the main trends in plant species composition and reproductive and dispersal traits (pollen vector, diaspore appendages, dispersal of diaspores and fruit type) in central Mediterranean summits in relation to environmental factors (altitude, aspect, debris cover and slope). Based on 114 plots, with floristic and environmental data collected in the year 2016 on alpine calcareous grasslands in the central Apennines, we explored how species composition varies in relation to environmental factors using CCA (canonical correspondence analysis). Then, we analyzed the relationships among species presence, the occurrence of reproductive and dispersal traits and environmental variables. We used for this analysis the fourth-corner model approach. Our results highlight a consistent response of floristic composition and of structural and ecological characteristics to environmental gradients, with elevation and debris cover being the most important ones. The environmental characteristics of the analyzed ecosystems (e.g., steep slopes and harsh environments) combined with the persistence of perennial plant species already present in each stand, the high precision of pollination and the prevalence of short-distance dissemination strategies should allow the calcareous endemic plant communities of the analyzed Mediterranean summits to be conserved at least for a mid-term period slowing down the expansion of the warm-adapted species, less adapted to the local environmental constrains.

The stability of moss populations on stream banks along two first-order, temperate-forest, headwater streams

The occurrence of terrestrial mosses in temperate deciduous forests is limited by abundant leaf litter that covers almost all of the soil, except along stream banks where mineral substrates are exposed by wind. However, stream banks are also subject to erosion that is a major disturbance for moss populations. Utilizing transplants and observations over a three period (2015–2017), we examined maintenance of current populations and establishment of new ones along the banks of two headwater streams, one in Virginia (Meadowood) and one in Illinois (Vishnu). Of the 224 plots, some with and some without mosses, that we monitored at the two stream study areas, 78 (35%) were lost to erosion or stochastic events. Areas with established moss populations had similar losses than areas without mosses (43% lost vs. 39% lost); however, losses at the two sites were very different—in Illinois, 41% of the original plots were lost, compared to 29% in Virginia. These differences in losses from erosion correspond to 32% greater number of high (>2 cm) and extreme (>4 cm) precipitation events at the Illinois site. In general, areas with mosses were lost at the same rate as those with leaf-covered bare soil. Leaf cover of moss plots, measured at height of the autumn leaf fall, averaged 12% at the Illinois site and 14% in Virginia, compared to plots without mosses that averaged 56–57% leaf cover, indicating that established moss populations are associated with exposed microsites, whereas microsites without mosses have high leaf cover. We examined the potential for colonization of new sites using transplants. Mosses transplanted onto bare soil successfully established 52% of the time, with unsuccessful ones mostly lost due to high leaf cover. Bare areas that did not receive transplants were colonized only 14% of the time, while bare areas within established moss populations were recolonized 48% of the time. We conclude that: 1) stream bank bryophyte populations are limited by leaf litter on the forest-side and erosion on the stream-side—the latter influenced by high precipitation events; 2) new potential habitats are often covered by leaf litter prohibiting establishment; 3) establishment of new populations in the local area appear to also be limited by availability (or dispersal) of diaspores; and 4) despite these limitations, losses from erosion appear to be counter-balanced by persistence and slow expansion of existing populations that remain largely litter free owing to slightly raised canopy surfaces and rapid recolonization of internally disturbed microsites.

Impacts of the Invasive European Red Ant (Myrmica rubra (L.): Hymenoptera; Formicidae) on a Myrmecochorous System in the Northeastern United States.

We investigated the impact of an invasive ant species from Europe, Myrmica rubra (L.), on a myrmecochorous system (seeds dispersed by ants) in its invaded range in North America. We assessed: 1) how M. rubra process the myrmecochorous diapsores (seeds and elaiosome as a single dispersal unit transported by ants) in comparison with native ants; 2) its preference for common native and invasive diaspore species relative to native ants; 3) how far they disperse diaspores in the field; and 4) the diaspore removal rate by invertebrates and vertebrates in infested areas compared to noninvaded sites. Field experiments demonstrated higher diaspore removal rates over a 10-min and 24-h period by M. rubra compared to native ants. M. rubra's diaspore dispersal distance was 40% greater compared to native ants. In two of three laboratory studies and one field study, there was no significant difference between the seed species which M. rubra and native ants selected. Our data suggest no long-term deleterious effects of M. rubra's invasion on diaspore dispersal in the Maine plant community that is comprised of both native and invasive species. This implies that M. rubra benefits from the myrmechorous plant species' diaspores by increasing their dispersal range away from the parent plant and potentially reducing seed predation. However, it is not known whether the fact that the native ant fauna and M. rubra are attracted to the same plant species' diaspores creates a high level of competition between the ants with deleterious effects on the native ant community.

Internal and External Dispersal of Plants by Animals: An Aquatic Perspective on Alien Interference.

Many alien plants use animal vectors for dispersal of their diaspores (zoochory). If alien plants interact with native disperser animals, this can interfere with animal-mediated dispersal of native diaspores. Interference by alien species is known for frugivorous animals dispersing fruits of terrestrial plants by ingestion, transport and egestion (endozoochory). However, less attention has been paid to possible interference of alien plants with dispersal of diaspores via external attachment (ectozoochory, epizoochory or exozoochory), interference in aquatic ecosystems, or positive effects of alien plants on dispersal of native plants. This literature study addresses the following hypotheses: (1) alien plants may interfere with both internal and external animal-mediated dispersal of native diaspores; (2) interference also occurs in aquatic ecosystems; (3) interference of alien plants can have both negative and positive effects on native plants. The studied literature revealed that alien species can comprise large proportions of both internally and externally transported diaspores. Because animals have limited space for ingested and adhering diaspores, alien species affect both internal and external transport of native diaspores. Alien plant species also form large proportions of all dispersed diaspores in aquatic systems and interfere with dispersal of native aquatic plants. Alien interference can be either negative (e.g., through competition with native plants) or positive (e.g., increased abundance of native dispersers, changed disperser behavior or attracting additional disperser species). I propose many future research directions, because understanding whether alien plant species disrupt or facilitate animal-mediated dispersal of native plants is crucial for targeted conservation of invaded (aquatic) plant communities.

Epizoochorous dispersal by ungulates depends on fur, grooming and social interactions.

The transport phase of the animal‐mediated plant dispersal process is critical to dispersal effectiveness as it determines the spatial distribution of the diaspores released and their chance for further recruitment. Assessing this specific phase of the dispersal process generally requires combining diaspore retention times with the associated distances covered. Here, we specifically tested the effect of grooming behavior, interindividual contacts and ungulate fur on diaspore retention times and associated dispersal distances for the hooked diaspores of Xanthium strumarium L. experimentally attached to tamed individuals of three ungulate species. We used a comparative approach based on differing fur quality on different body zones of these three ungulates. During 6‐hr sessions, we monitored for grooming and social interactions that may induce intended or inadvertent diaspore detachment. Additionally, we proposed innovative approaches to directly assessing diaspore dispersal distances by red deer in situ. Fat‐tailed functions fitted diaspore retention time, highlighting the potential for long‐distance dispersal events. The longer the hair, the higher the retention capacity of diaspores in the animal's fur. As predicted, donkey retained diaspores longer than red deer and dwarf goat; and we also confirmed that diaspores attached to the short hair of the head fell off more quickly than did those on the other body zones. Dwarf goat groomed more often than both red deer and donkey, but also when it carried diaspores. Up to 14% of the diaspores detached from animal fur after specific grooming behavior. We observed, in controlled conditions, for the first time and for each ungulate species, interindividual transfers of diaspores, representing 5% of the diaspores attached to animals’ fur. Our results militate for incorporating animal behavior into plant dispersal modeling approaches.

Experimental Measurements of Terminal Velocity of Fern Spores

The dispersal of diaspores is a key process for successful reproduction, survival and evolution of plants. To model the dispersal of biological propagules (e.g., spores, pollen) it is necessary to measure their terminal velocity (Vt) in air. In this study, we used a new method based on video image analysis to measure Vt of spores of seven fern taxa. The average Vt of fern spores was 7.0 cm s−1, but varied among species from 1.6 to 11.3 cm s−1. Similar values were reported previously for airborne particles of mosses and seed plants. Spores of Danaea nodosa and Lophosoria quadripinnata had a lower Vt than other spores of similar size, perhaps owing to their surface ornamentation that increases their drag coefficient, or an air cavity, which diminishes their density. The reliability of the video image analysis method used here on fern spores was verified by comparing observed and theoretically calculated Vt of glass beads of known diameter and density. This method also allows the observation of spore behavior (e.g., rotation) as they move through the air. Because the method is relatively easy and inexpensive, it can promote future aerobiological research on other biological airborne particles as well.

Biogeographic Events Are Not Correlated with Diaspore Dispersal Modes in Boraginaceae

Long-distance dispersal seems to be the main biogeographic event responsible for intriguing distribution patterns in plant groups in which sister taxa are separated by thousands of kilometers of distance across oceans and continents. The biotic and abiotic mechanisms behind such dispersal events are poorly understood and many attempts have been made to explain how plants can manage to disperse and survive these long journeys. The biogeographic history of Boraginaceae, a subcosmopolitan plant family with many disjunct clades, is here addressed and analyzed in the context of the different dispersal modes exhibited by the species. The lack of a clear pattern between the main dispersal events in Boraginaceae and the phylogenetic distribution of the dispersal modes indicates that no single dispersal mechanism can be associated with the events of dispersal in the family. Moreover, adaptations to different dispersal agents and unassisted dispersal modes in some clades might have promoted the diversification of Boraginaceae in various habitats across several continents. Our study reveals that long-distance dispersal is a very complex process that needs to be analyzed in the context of climatic and environmental changes and the response of plants and their dispersal vectors to these variable conditions.

The assembly of ant-farmed gardens: mutualism specialization following host broadening.

Ant-gardens (AGs) are ant/plant mutualisms in which ants farm epiphytes in return for nest space and food rewards. They occur in the Neotropics and Australasia, but not in Africa, and their evolutionary assembly remains unclear. We here use phylogenetic frameworks for important AG lineages in Australasia, namely the ant genus Philidris and domatium-bearing ferns (Lecanopteris) and flowering plants in the Apocynaceae (Hoya and Dischidia) and Rubiaceae (Myrmecodia, Hydnophytum, Anthorrhiza, Myrmephytum and Squamellaria). Our analyses revealed that in these clades, diaspore dispersal by ants evolved at least 13 times, five times in the Late Miocene and Pliocene in Australasia and seven times during the Pliocene in Southeast Asia, after Philidris ants had arrived there, with subsequent dispersal between these two areas. A uniquely specialized AG system evolved in Fiji at the onset of the Quaternary. The farming in the same AG of epiphytes that do not offer nest spaces suggests that a broadening of the ants' plant host spectrum drove the evolution of additional domatium-bearing AG-epiphytes by selecting on pre-adapted morphological traits. Consistent with this, we found a statistical correlation between the evolution of diaspore dispersal by ants and domatia in all three lineages. Our study highlights how host broadening by a symbiont has led to new farming mutualisms.

“Sticky invasion” – the physical properties ofPlantago lanceolataL. seed mucilage

The mucilage envelope of seeds has various functions including the provision of different ways for the dispersal of diaspores. Chemical composition and water content of the mucilage yield particular adhesive and frictional properties in the envelope that also influence the dispersal of seeds. To determine the physical properties of Plantago lanceolata seed mucilage we studied (1) composition, (2) desiccation, (3) adhesion, and (4) friction properties of the mucilage under different hydration conditions. We revealed the presence of cellulose fibrils in the mucilage, which are responsible for a continuous and even distribution of the mucilaginous layer on the seed surface. The measured values of adhesive and frictional properties differed significantly in comparison to the previously studied pectic mucilage of Linum usitatissimum. Also, the water loss from the cellulose mucilage was more rapid. The obtained different values can result from the presence of cellulose fibrils and their interaction with pectins in the mucilage. Because of this feature the mucilage of P. lanceolata may represent a more regularly ordered and stabile system than the pectic mucilage of flax, which lacks cellulose. In spite of the fact that P. lanceolata mucilage revealed different adhesive and frictional properties than the pectic mucilage, it still demonstrates an effective system promoting zoochoric seed dispersal. Cellulose may additionally prevent the mucilage against loss from the seed surface.

Diversity and ecology of vascular plants established on the extant world-longest ancient city wall of Nanjing, China

Spontaneous vegetation established on the city wall constitutes a characteristic greenspace within the urban matrix. Nanjing city wall of the Ming Dynasty (NJCW), as an extraordinary huge defensive masonry project, was built in 1393, the extant, basically intact ancient city wall is 25.09km long, 9–26m high, and is protected now as a key national cultural relic. Species composition and life forms of the vascular plants established on the vertical or inclined wall surfaces of NJCW were investigated, and its diaspore sources and dispersal modes were also analyzed. Totally, 159 species in 125 genera of 70 families were found inhabiting the joints between bricks or between block stones, trees, shrubs and woody lianas accounts for 51.57% of the species assemblage, while herbaceous plant species makes up 48.43% of them. Fifteen alien species were found colonizing NJCW, including 12 invasive species. Six 100-m-long quadrats were sampled in different segments of NJCW, each quadrat contained 39–77 species, and 755–3006 individuals. In total, 10785 individuals of vascular plants were recorded, consisting of 104 species in 89 genera of 56 families. 65.25% of the total individuals, and 53.85% of the total species are adapted to the primary dispersal of diaspores by wind, whereas 34.75% of the individual assemblage, and 46.15% of the species assemblage are adapted to the primary dispersal of seeds by birds. A bird-dispersed, native pioneer tree, Broussonetia papyrifera, was the most abundant species among the six quadrats, even developed coppices on the vertical wall surface. Location and aspect of the quadrats may have affected the species diversity of vascular plants established on its wall surfaces. A diversity of vascular plants established on NJCW, as a valuable urban ecological heritage, is worthy of sustainable wall management, while management priorities should be given to those large trees inhabiting the walls made of bricks, and to the invasive alien species to prevent them from further spreading over the adjacent urban habitats.

Distribution of vascular plant species in woodland patches of Ojców National Park (southern Poland) in relation to seed dispersal

<p>Plant diaspore dispersal is a fundamental process affecting the development of forest vegetation and its natural regeneration, especially with regard to typical woodland species, which spread slowly and form short-term soil seed banks. Most of these species have poor seed dispersal mechanisms, which is the major cause of their very slow expansion.</p><p>The following questions were asked: (<em><strong>i</strong></em>) is there a relationship between the age of a woodland and the presence of forest vascular plant species representing different seed dispersal types; (<em><strong>ii</strong></em>) how do the proportions change between species representing different seed dispersal types in relation to the age of woodland; (<em><strong>iii</strong></em>) what factors determine the presence of species representing a given seed dispersal type; (<em><strong>iv</strong></em>) which factors affect the presence and which ones influence the abundance of selected woodland species? A multiple regression models were developed based on data obtained from 144 woodland patches designated for the study. A probit regression analysis was performed for selected species exhibiting various seed dispersal models.</p><p>Woodland plants of all seed dispersal types show a significant relationship with the age of woodland, starting from the strongest linkage: anemochores, myrmecochores, endozoochores, epizoochores, barochores, autochores. As the woodland ages, the proportion of forest myrmecochores and anemochores grows, whilst the proportion of autochores, epizoochores and endozoochores shrinks. Results obtained indicate that the direct proximity of ancient woodland has a major effect on the occurrence of more poorly dispersing plants in recent woodlands, such as myrmecochores and heavy anemochores.</p>