Relative Importance Of Dispersal Limitation Research Articles

Soil bacterial communities and co-occurrence changes associated with multi-nutrient cycling under rice-wheat rotation reclamation in coastal wetland

Coastal reclamation is a global threat to coastal wetland ecosystems, but the impacts of coastal reclamation on belowground biodiversity and their consequences for ecosystem nutrient cycling remain poorly understood. In this study, we examined soil bacterial communities, bacterial co-occurrence pattern and soil multi-nutrient cycling index after natural vegetated coastal wetlands were converted for 6-year and 30-year rice-wheat rotation fields. The soil multi-nutrient cycling index was higher in 6-year and 30-year rice-wheat rotation fields than natural vegetated coastal wetlands. For bacterial community, rice-wheat rotation reclamation increased soil bacterial alpha diversity but decreased beta diversity and co-occurrence network complexity than those in the vegetated coastal wetland. Rice-wheat rotation reclamation also changed soil bacterial community assemblages by increasing the relative abundance of Actinobacteriota and Desulfobacterota while decreasing the relative abundance of Alphaproteobacteria and Gammproteobacteria. Changes in the relative importance of dispersal limitation and homogenizing dispersal mainly controlled the variations in soil bacterial community assemblages. Soil bacterial community variations induced by rice-wheat reclamation were strongly related to soil multi-nutrient cycling, especially bacterial connection complexity. Our results provide experimental support that belowground microbial interactions are crucial for maintaining ecosystem functioning.

Assembly processes of abundant and rare microbial communities in orchard soil under a cover crop at different periods

Soil microorganisms play key roles in agricultural ecosystems. However, little is known about their dynamic diversity patterns and community assembly processes, especially in the rare microbial biosphere in agriculture systems. In this study, we determined the responses of diversities and assembly processes of abundant and rare bacterial and fungal subcommunities to agricultural practice (i.e. cover crop) in a semiarid orchard soil by using 16S and ITS rRNA gene sequencing. We found that the community structures of abundant and rare taxa exhibited a similar response to cover crop or growth periods. Growth periods significantly changed the bacterial and fungal subcommunities structure. Only the fungal subcommunities structure was affected by cover crop. The community assembly of abundant and rare fungi was respectively dominated by stochastic process and deterministic process and less affected by cover crop and growth period. For abundant bacteria, the assembly process was dominated by heterogeneous and undominated processes, and the importance of heterogeneous selection process was increased by cover crop at setting and maturing period. The assembly process of rare bacterial community was dominated by a homogeneous selection and the relative importance of dispersal limitation was increased at maturing period. We also found that the assembly processes of abundant taxa were significantly related to the soil DON, NH4+-N, NO3–-N and pH, while the assembly processes of rare taxa were significantly related to the soil DOC, AP and SOC. Our results provide new insights into the formation of the microbial community in orchard soil under a cover crop, especially the seasonal succession of abundant and rare bacterial and fungal subcommunities.

Little trace of floristic homogenization in peri‐urban Andean secondary forests despite high anthropogenic transformation

Abstract Pervasive human impact in heavily transformed landscapes may lead disturbance‐adapted species to thrive, resulting in floristic homogenization across forest stands. However, environmental heterogeneity and dispersal limitation may be antagonistic forces to homogenization, maintaining inherent floristic differentiation across sites. We evaluated the extent to which peri‐urban Andean forests are undergoing floristic homogenization in both late‐ and early‐successional stands. We considered seedling assemblages as well, as they provide key insights into forests’ future. We then quantified the relative importance of dispersal limitation and environmental filtering in determining the observed patterns of floristic similarity across the landscape. We used tree, seedling, soil and climatic data from six sites located in the high plain where Bogotá lies (Colombia). Within each site, we established six 20 × 20 m plots, three in early‐successional stands and three in late‐successional stands, for a total of 36 plots. To evaluate the extent of floristic homogenization, we defined tree floristic similarity among late‐successional stands as a baseline, reflecting our best‐guess of the original species composition that would have once occurred previous to intense anthropogenic intervention. Tree floristic turnover across the landscape was alike in late‐ and in early‐secondary stands, a finding that does not support the homogenization scenario. Seedling species composition, in contrast, was more homogeneous among early‐ than among late‐secondary stands, an outcome suggestive of homogenization. The relative importance of spatial and environmental drivers shifted between life stages. Distance between plots was the best predictor of tree species dissimilarity (29% of variance explained), whereas seedling compositional variation was more sensitive to changes in environmental conditions (41% of the variance explained). Relative humidity and several variables related to soil fertility showed a significant effect on floristic dissimilarity across the landscape, although significant factors were often different between life stages. Synthesis. Despite high anthropogenic transformation, we found little trace of floristic homogenization in these peri‐urban landscapes. Inherent floristic differentiation, promoted both by dispersal limitation and environmental heterogeneity, suggests that all patches are important to the conservation in these Andean forests, critical centres of endemism.

Homogeneous selection shapes free‐living and particle‐associated bacterial communities in subtropical coastal waters

AbstractAimIn microbial biogeography, it is crucial to link spatial patterns with underlying drivers in natural ecosystems. Bacterial communities driving key biogeochemical processes in coastal zones, which are important interfaces between terrestrial and marine ecosystems, are affected by perturbations due to both natural and anthropogenic factors. However, the assembly of bacterioplankton communities, either free‐living (FL) or particle‐associated, in coastal ecosystems is still poorly understood.LocationCoastal South China Sea influenced by the Pearl River (SCSPR).MethodsIn this study, we investigated FL, nanoparticle‐associated (NA) and microparticle‐associated (MA) bacterial communities in the SCSPR, using environmental DNA metabarcoding based on the V4 region of the 16S rRNA gene. We assessed the relative importance of ecological processes using null model analyses based on a two‐step framework.ResultsWe found that the observed amplicon sequence variants (ASVs) increased from FL, NA to MA communities, and a remarkably pervasive core set of ASVs closely belonged to potential hydrocarbonoclastic bacteria with wide habitat niche breadths. Analyses of similarity tests revealed that FL, NA and MA communities differed significantly but weakly, based on unweighted (R = 0.27, p < .001) and weighted (R = 0.18, p < .001) dissimilarities. Fundamental regulation of bacterial communities via homogeneous selection was most prominent in FL (90%), followed by NA (86.8%) and MA (73.3%), whereas the relative importance of dispersal limitation was most pronounced in MA (13.2%), followed by NA (11.7%) and FL (8.6%).Main conclusionsBacterial communities in the SCSPR can be predominantly influenced by human activities, as indicated by the core ASVs closely related to hydrocarbonoclastic bacteria. Importantly, anthropogenic influences can temporally overwhelm the large environmental heterogeneities in coastal ecosystems. This study fills knowledge gaps in bacterial community assembly, which may facilitate future studies regarding anthropogenic influences on coastal ecosystems.

The impact of dispersal, plant genotype and nematodes on arbuscular mycorrhizal fungal colonization

While the majority of parasitic and mutualistic microbes have the potential for long-range dispersal, the high turnover in community composition among nearby hosts has often been interpreted to reflect dispersal constraints. To resolve this apparent contradiction, we need further insights into the relative importance of dispersal limitation, host genotype and the biotic environment on the colonization process. We focused on the important root symbionts, the arbuscular mycorrhizal (AM) fungi. We studied AM fungal colonization ability in a controlled mesocosm setting, where we placed Plantago lanceolata plants belonging to four different genotypes in sterile soil at 10, 30 and 70 cm from a central AM fungal inoculated P. lanceolata plant. In part of the mesocosms, we also inoculated the source plants with nematodes. AM fungi colonized receiver plants <1 m away over the course of ten weeks, with a strong effect of distance from source plant on AM fungal colonization. Plant genotype influenced AM fungal colonization during the early stages of colonization, while nematode inoculation had no effect on AM fungal colonization. Overall, the effect of both dispersal limitation and plant genetic variation may underlie the small-scale heterogeneity found in natural AM fungal communities.

Distinct large-scale biogeographic patterns of fungal communities in bulk soil and soybean rhizosphere in China

Fungi play a crucial role in the agroecological system; however, little is known about their large-scale biogeographical patterns and how various ecological processes contribute to community assembly, especially in the crop rhizosphere. In this study, we investigated the spatial distribution and community assembly of fungi in the bulk soil and rhizosphere of soybean collected from 43 sites across China using high-throughput sequencing. The alpha diversity of the rhizosphere was lower than that of bulk soil. The fungal community structures of the two soil compartments were distinct. Fungal communities in the rhizosphere had a steeper distance-decay relationship slope between sampled sites than those in bulk soil, suggesting a greater influence of historical processes (geographical separation) in the rhizosphere. The relative importance of dispersal limitation and environmental filtering for the fungal community composition differed between bulk soil and rhizosphere. Sloan neutral model analysis suggested that niche-based processes dominated the assemblage of fungal communities in the two soil compartments, while neutral processes had a weaker influence in the rhizosphere than in bulk soil. Additionally, we analyzed the structures of abundant and rare fungal sub-communities in each soil compartment. Rare sub-communities were more strongly influenced by dispersal limitation than abundant sub-communities. These results expand the current understanding of root-associated fungal community biogeography in agricultural soils on a large scale.

The multifactorial effects of dispersal on biodiversity in environmentally forced metacommunities

AbstractDisentangling the effects of dispersal and environmental heterogeneity on biodiversity is a central goal in ecology. Although metacommunity structure can be partitioned into spatial and environmental fractions, it remains unclear whether these statistical results can be used to infer the relative importance of dispersal limitation (spatial fraction) and environmental forcing (environmental fraction). Using an environmentally forced, spatially explicit metacommunity model, we show that the distinct effects of the mean (advection) and the standard deviation (diffusion) of the dispersal kernel on biodiversity are not easily detectable via variation partitioning alone. Although increasing dispersal ultimately leads to a decrease in the spatial fraction due to reduced dispersal limitation and greater species sorting, the magnitude of the spatial fraction depends on the complex interplay between the nature of dispersal and the type of boundary conditions in the metacommunity. Indeed, metacommunities characterized by either high or low dispersal can exhibit a small spatial fraction. A case study of a marine metacommunity experiencing strong alongshore transport is consistent with these findings, as the size of the spatial fraction is not associated with dispersal. Overall, our results suggest that accounting for the nature of environmental forcing as well as the multifactorial effects of dispersal is critical for understanding how ecological and environmental processes give rise to biodiversity across spatial scales.

Environmental heterogeneity blurs the signature of dispersal syndromes on spatial patterns of woody species in a moist tropical forest.

We assessed the relative importance of dispersal limitation, environmental heterogeneity and their joint effects as determinants of the spatial patterns of 229 species in the moist tropical forest of Barro Colorado Island (Panama). We differentiated five types of species according to their dispersal syndrome; autochorous, anemochorous, and zoochorous species with small, medium-size and large fruits. We characterized the spatial patterns of each species and we checked whether they were best fitted by Inhomogeneous Poisson (IPP), Homogeneous Poisson cluster (HPCP) and Inhomogeneous Poisson cluster processes (IPCP) by means of the Akaike Information Criterion. We also assessed the influence of species’ dispersal mode in the average cluster size. We found that 63% of the species were best fitted by IPCP regardless of their dispersal syndrome, although anemochorous species were best described by HPCP. Our results indicate that spatial patterns of tree species in this forest cannot be explained only by dispersal limitation, but by the joint effects of dispersal limitation and environmental heterogeneity. The absence of relationships between dispersal mode and degree of clustering suggests that several processes modify the original spatial pattern generated by seed dispersal. These findings emphasize the importance of fitting point process models with a different biological meaning when studying the main determinants of spatial structure in plant communities.

Mycorrhizal specificity does not limit the distribution of an endangered orchid species.

What factors determine the distribution of a species is a central question in ecology and conservation biology. In general, the distribution of plant species is assumed to be controlled by dispersal or environmentally controlled recruitment. For plant species which are critically dependent on mycorrhizal symbionts for germination and seedling establishment, specificity in mycorrhizal associations and availability of suitable mycorrhizal fungi can be expected to have a major impact on successful colonization and establishment and thus ultimately on a species distribution. We combined seed germination experiments with soil analyses and fungal assessments using 454 amplicon pyrosequencing to test the relative importance of dispersal limitation, mycorrhizal availability and local growth conditions on the distribution of the orchid species Liparis loeselii, which, despite being widely distributed, is rare and endangered in Europe. We compared local soil conditions, seed germination and mycorrhizal availability in the soil between locations in northern Belgium and France where L.loeselii occurs naturally and locations where conditions appear suitable, but where adults of the species are absent. Our results indicated that mycorrhizal communities associating with L.loeselii varied among sites and plant life cycle stages, but the observed variations did not affect seed germination, which occurred regardless of current L.loeselii presence and was significantly affected by soil moisture content. These results indicate that L.loeselii is a mycorrhizal generalist capable of opportunistically associating with a variety of fungal partners to induce seed germination. They also indicate that availability of fungal associates is not necessarily the determining factor driving the distribution of mycorrhizal plant species.

Disentangling the drivers of taxonomic and phylogenetic beta diversities in disturbed and undisturbed subtropical forests.

Understanding the relative importance of dispersal limitation and environmental filtering processes in structuring the beta diversities of subtropical forests in human disturbed landscapes is still limited. Here we used taxonomic (TBD) and phylogenetic (PBD), including terminal PBD (PBDt) and basal PBD (PBDb), beta diversity indices to quantify the taxonomic and phylogenetic turnovers at different depths of evolutionary history in disturbed and undisturbed subtropical forests. Multiple linear regression model and distance-based redundancy analysis were used to disentangle the relative importance of environmental and spatial variables. Environmental variables were significantly correlated with TBD and PBDt metrics. Temperature and precipitation were major environmental drivers of beta diversity patterns, which explained 7–27% of the variance in TBD and PBDt, whereas the spatial variables independently explained less than 1% of the variation for all forests. The relative importance of environmental and spatial variables differed between disturbed and undisturbed forests (e.g., when Bray-Curtis was used as a beta diversity metric, environmental variable had a significant effect on beta diversity for disturbed forests but had no effect on undisturbed forests). We conclude that environmental filtering plays a more important role than geographical limitation and disturbance history in driving taxonomic and terminal phylogenetic beta diversity.

Soil microbial community variation correlates most strongly with plant species identity, followed by soil chemistry, spatial location and plant genus.

Soil ecologists have debated the relative importance of dispersal limitation and ecological factors in determining the structure of soil microbial communities. Recent evidence suggests that 'everything is not everywhere', and that microbial communities are influenced by both dispersal limitation and ecological factors. However, we still do not understand the relative explanatory power of spatial and ecological factors, including plant species identity and even plant relatedness, for different fractions of the soil microbial community (i.e. bacterial and fungal communities). To ask whether factors such as plant species, soil chemistry, spatial location and plant relatedness influence rhizosphere community composition, we examined field-collected rhizosphere soil of seven congener pairs that occur at Bodega Bay Marine Reserve, CA, USA. We characterized differences in bacterial and fungal communities using terminal-restriction fragment length polymorphism. Plant species identity was the single best statistical predictor of both bacterial and fungal community composition in the root zone. Soil microbial community structure was also correlated with soil chemistry. The third best predictor of bacterial and fungal communities was spatial location, confirming that everything is not everywhere. Variation in microbial community composition was also related to combinations of spatial location, soil chemistry and plant relatedness, suggesting that these factors do not act independently. Plant relatedness explained less of the variation than plant species, soil chemistry, or spatial location. Despite some congeners occupying different habitats and being spatially distant, rhizosphere fungal communities of plant congeners were more similar than expected by chance. Bacterial communities from the same samples were only weakly similar between plant congeners. Thus, plant relatedness might influence soil fungal, more than soil bacterial, community composition.

Environmental filtering affects soil fungal community composition more than dispersal limitation at regional scales

The relative importance of dispersal limitation versus environmental filtering for community assembly has received much attention for macroorganisms. These processes have only recently been examined in microbial communities. Instead, microbial dispersal has mostly been measured as community composition change over space (i.e., distance decay). Here we directly examined fungal composition in airborne wind currents and soil fungal communities across a 40 000 km2 regional landscape to determine if dispersal limitation or abiotic factors were structuring soil fungal communities. Over this landscape, neither airborne nor soil fungal communities exhibited compositional differences due to geographic distance. Airborne fungal communities shifted temporally while soil fungal communities were correlated with abiotic parameters. These patterns suggest that environmental filtering may have the largest influence on fungal regional community assembly in soils, especially for aerially dispersed fungal taxa. Furthermore, we found evidence that dispersal of fungal spores differs between fungal taxa and can be both a stochastic and deterministic process. The spatial range of soil fungal taxa was correlated with their average regional abundance across all sites, which may imply stochastic dispersal mechanisms. Nevertheless, spore volume was also negatively correlated with spatial range for some species. Smaller volume spores may be adapted to long-range dispersal, or establishment, suggesting that deterministic fungal traits may also influence fungal distributions. Fungal life-history traits may influence their distributions as well. Hypogeous fungal taxa exhibited high local abundance, but small spatial ranges, while epigeous fungal taxa had lower local abundance, but larger spatial ranges. This study is the first, to our knowledge, to directly sample air dispersal and soil fungal communities simultaneously across a regional landscape. We provide some of the first evidence that soil fungal communities are mostly assembled through environmental filtering and experience little dispersal limitation.

Ground layer plant species turnover and beta diversity in southern-European old-growth forests.

Different assembly processes may simultaneously affect local-scale variation of species composition in temperate old-growth forests. Ground layer species diversity reflects chance colonization and persistence of low-dispersal species, as well as fine-scale environmental heterogeneity. The latter depends on both purely abiotic factors, such as soil properties and topography, and factors primarily determined by overstorey structure, such as light availability. Understanding the degree to which plant diversity in old-growth forests is associated with structural heterogeneity and/or to dispersal limitation will help assessing the effectiveness of silvicultural practices that recreate old-growth patterns and structures for the conservation or restoration of plant diversity. We used a nested sampling design to assess fine-scale species turnover, i.e. the proportion of species composition that changes among sampling units, across 11 beech-dominated old-growth forests in Southern Europe. For each stand, we also measured a wide range of environmental and structural variables that might explain ground layer species turnover. Our aim was to quantify the relative importance of dispersal limitation in comparison to that of stand structural heterogeneity while controlling for other sources of environmental heterogeneity. For this purpose, we used multiple regression on distance matrices at the within-stand extent, and mixed effect models at the extent of the whole dataset. Species turnover was best predicted by structural and environmental heterogeneity, especially by differences in light availability and in topsoil nutrient concentration and texture. Spatial distances were significant only in four out of eleven stands with a relatively low explanatory power. This suggests that structural heterogeneity is a more important driver of local-scale ground layer species turnover than dispersal limitation in southern European old-growth beech forests.

Recruitment limitation of dominant tree species with varying seed masses in a subtropical evergreen broad-leaved forest

Recruitment limitation has been hypothesized to promote the maintenance of high species diversity in forests by slowing down competitive exclusion. However, the difference of recruitment limitation for tree species with varying seed masses, which is a common phenomenon in tropical or subtropical forests, is largely unknown. In this study we conducted a seed sowing experiment for five dominant tree species with varying seed mass (a proxy of dispersal ability) in a subtropical evergreen broad-leaved forest at different successional stages to test the hypothesis that the determinants of species recruitment vary with their seed masses in Heishiding Nature Reserve (Guangdong Province, China). The effects of seed predators, soil pathogens, light conditions, plant litter, seed additions, and the presence of adult conspecific trees on the performance of seeds and seedlings for the five species were examined. We particularly investigated the effects of habitat hazards and seed size on the relative importance of dispersal limitation and establishment limitation. The results show that all five sowing species experienced recruitment limitation at the microsite level, although the causes of the limitation of these species varied between pathogen infection, animal predation, litter covering and shading. Seedling recruitment of the wind-dispersed, small-seeded species was mostly limited by microsite condition, while large-seeded species were mostly limited by dispersal ability.

Dispersal limitation, speciation, environmental filtering and niche differentiation influence forest tree communities in West Polynesia

AbstractAimRegional patterns of forest composition in West Polynesia were analysed to determine the relative importance of dispersal limitation, speciation, environmental filtering and biotic interactions.LocationWest Polynesia (Fiji, Tonga, Samoa).MethodsWe applied clustering and indicator species analysis to presence/absence data for 397 tree taxa in 338 forest plots to detect groups of plots sharing similar species composition. Patterns of plot composition and co‐occurrence of congeneric species were compared between archipelagos for evidence of dispersal limitation, speciation, and environmental filtering versus competitive displacement or niche differentiation across the three archipelagos at the local (plot) and regional scales.ResultsDispersal limitation was evident in the compositional segregation of inland rain forests across the three archipelagos, whereas compositional overlap was widespread for coastal forests, which are composed of species dispersed by water. Within genera, species numbers attenuated from Fiji to Tonga to Samoa, but speciation also contributed to compositional differences in all three island groups. Environmental filtering was suggested by the distinct composition of both secondary and mature inland rain forest versus coastal forest. At the local scale, however, clumping of congeners, which might suggest fine‐scale environmental filtering, was observed for only a minority of inland forest genera. Most genera showed either overdispersion, suggesting competitive displacement or niche differentiation, or patterns not significantly different from random.Main conclusionsWell‐established biogeographical patterns of dispersal limitation and speciation contribute to West Polynesian tree diversity at the community scale. Environmental filtering and competitive displacement further structure forest communities; the evidence from this study suggests that environmental filtering is more important at a landscape scale, while competitive displacement may be more important at a local scale, although their relative importance varies considerably among taxa.

The relative importance of dispersal limitation and habitat preference in shaping spatial distribution of saplings in a tropical moist forest: a case study along a combination of hydromorphic and canopy disturbance gradients

• Introduction Various processes contribute to shaping the local assemblage of species in hyperdiverse tropical forest. The relative contribution of environmental factors and dispersal limitation in determining the spatial distribution of saplings at local scale is unclear.

Metacommunity assembly and sorting in newly formed lake communities

new habitats are created, community assembly may follow independent trajectories, since the relative importance of dispersal limitation, priority effects, species interactions, and environmental gradients can vary as assembly proceeds. Unfortunately, tracking community colonization and composition across decades is challenging. We compiled a multiyear community composition data set and reconstructed past communities with remains from sediment cores to investigate cladoceran assembly dynamics in six older (1920s) and two more recently formed (1950s) lakes. We found that current communities cluster along a gradient of thermal stratification that is known to influence predation intensity. Assembling communities showed evidence for a greater influence of species sorting and a reduced influence of spatial structure since the first colonizations. However, lake community trajectories varied considerably, reflecting different colonization sequences among lakes. In the older lakes, small-bodied cladocerans often arrived much earlier than large-bodied cladocerans, while the two younger lakes were colonized much more rapidly, and one was quickly dominated by a large-bodied species. Thus, by combining contemporary community data with paleoecological records, we show that assembly history influences natural community structure for decades while patterns of ecological sorting develop.

Limitations to seedling establishment in a mesic Hawaiian forest

While invasive species may be visible indicators of plant community degradation, they may not constitute the only, or even the primary, limitation to stand regeneration. We used seed-augmentation and grass-removal experiments under different canopy conditions to assess the relative importance of dispersal limitation, resource availability, and competition on seedling establishment in the understory shrubs Sophora chrysophilla, Dodonea viscosa, and Pipturus albidus in a montane mesic forest in Hawaii. The study location was an Acacia koa-Metrosideros polymorpha forest at 1000-1500 m elevation on the leeward side of Hawaii Island; it is a closed-canopy forest historically subject to logging and grazing by cattle and sheep and currently dominated by the exotic grass, Ehrharta stipoides, in the herb layer. Seedling establishment after 1 and 2 years was strongly dispersal limited in Sophora and Dodonea, but not in Acacia, a non-augmented species in which abundant seedlings established, nor in Pipterus, in which only one seedling established in 2 years. Grass cover reduced seedling establishment in Acacia, Sophora, and Dodonea and, for the latter two species, seedling establishment was substantially greater in the warmer, more moist forest at the lowest elevation. Light, moisture, and resin-captured N and P were more strongly affected by elevation and canopy composition than by grass cover, but in most cases seedling establishment was not positively correlated with resource availability. Limitations to the establishment of woody seedlings in this forest-grassland mixture vary among species; however, both dispersal limitation and competition from a shade-tolerant grass are important deterrents to regeneration in these forests.

Population structure and adult plant performance of forest herbs in three contrasting habitats

In Flanders, forests have been subjected to subsequent periods of reclamation and reforestation, leading to a mosaic of forest patches of various ages and with different abiotic conditions, depending on the duration and intensity of the past agricultural activities. While extensive research has been done on the relative importance of dispersal limitation and establishment limitation in explaining colonization patterns of so‐called ancient forest plant species, little is known about the viability of populations of these species once they have colonized recent forests. Therefore, a comparative study on population structure and plant performance was carried out for three forest plant species with different colonization capacity (Primula elatior, Geum urbanum and Arum maculatum) in three different habitat types: ancient forests, recently established forests and small landscape elements (hedgerows). Contrary to the expectation, it was shown that adult plant performance – a combination of vegetative as well as reproductive characteristics – of the three species was generally higher in recent forests and small landscape elements. This also led to higher seedling densities and proportions in these habitat types. Adult densities, however, were extremely low in newly established forests, suggesting reduced seedling and juvenile survival under these circumstances, probably due to higher light availability and hence increased competition from species like Urtica dioica. Although there might be no immediate establishment limitation, installing a shrub layer in recent forests might enhance survival and result in a stable population structure. Hedgerows on the other hand seemed to contain viable populations of certain forest plant species and can therefore function as an important colonization source when incorporated in recently established forests.

The relative importance of dispersal limitation of vascular plants in secondary forest succession in Muizen Forest, Belgium

Abstract Distribution patterns (frequency and percentage cover) of 18 forest plant species were studied in 34 ha of mixed deciduous forest (Muizen Forest, north Belgium). Stands varied in age between 6 and more than 223 years and both slow and fast colonizing species were studied. Detailed land use history data were combined with the species distribution maps to identify species‐specific colonization sources and calculate colonization distances. A multiple logistic regression model was constructed with four covariables: pH (which can impose limits on the potential species‐distribution), secondary forest age, distance from nearest colonization source and age–distance interaction, to allow us to account for the gradual completion of colonization over time. We could distinguish species which are limited by both dispersal and recruitment (Primula elatior, Arum maculatum and Lamium galeobdolon), mainly by dispersal (Anemone nemorosa, Deschampsia cespitosa), mainly by recruitment (Paris quadrifolia and Polygonatum multiflorum) and by neither (Geum urbanum, Ranunculus ficaria, Glechoma hederacea, Aegopodium podagraria, Ajuga reptans, Adoxa moschatellina and Oxalis acetosella). The low colonizing capacity of ancient forest plants cannot be attributed to a single cause; rather both dispersal and recruitment are limiting but the relative importance varies.