Data from: Loss of animal seed dispersal increases extinction risk in a tropical tree species due to pervasive negative density dependence across life stages
Caughlin, T.T. ; Ferguson, J.M. ; Lichstein, J.W. ; Zuidema, Pieter ; Bunyavejchewin, S. ; Levey, D.J. - \ 2014
University of Florida
tropical forests - Anthropocene - fruit production - neighborhood model - seed addition experment - Saccopetalum - extinction - germination - tree demography - seedling demography - tree population - seedlings - neighborhood - tropical forest dynamics - negative density dependence - Miliusa - Annonaceae - seed dispersal - spatial model - Frugivory - Miliusa horsfieldii - overhunting
Overhunting in tropical forests reduces populations of vertebrate seed dispersers. If reduced seed dispersal has a negative impact on tree population viability, overhunting could lead to altered forest structure and dynamics, including decreased biodiversity. However, empirical data showing decreased animal-dispersed tree abundance in overhunted forests contradict demographic models which predict minimal sensitivity of tree population growth rate to early life stages. One resolution to this discrepancy is that seed dispersal determines spatial aggregation, which could have demographic consequences for all life stages. We tested the impact of dispersal loss on population viability of a tropical tree species, Miliusa horsfieldii, currently dispersed by an intact community of large mammals in a Thai forest. We evaluated the effect of spatial aggregation for all tree life stages, from seeds to adult trees, and constructed simulation models to compare population viability with and without animal-mediated seed dispersal. In simulated populations, disperser loss increased spatial aggregation by fourfold, leading to increased negative density dependence across the life cycle and a 10-fold increase in the probability of extinction. Given that the majority of tree species in tropical forests are animal-dispersed, overhunting will potentially result in forests that are fundamentally different from those existing now.
Of mice and oaks : conditional outcomes in a seed-dispersal mutualism
Suselbeek, L. - \ 2014
Wageningen University. Promotor(en): Herbert Prins; Frans Bongers, co-promotor(en): Patrick Jansen; Sip van Wieren. - Wageningen : Wageningen University - ISBN 9789462571020 - 120
zaadverspreiding - verspreiding - mutualisme - knaagdieren - boomvruchten - sus scrofa - apodemus sylvaticus - ecologie - seed dispersal - dispersal - mutualism - rodents - tree fruits - sus scrofa - apodemus sylvaticus - ecology
PhD Thesis (defence scheduled for 10 October 2014, 4pm) – abstracts for library
Of Mice and Oaks: conditional outcomes in a seed-dispersal mutualism
Rodents like to wood mouse store acorns to overcome winter, but some of the stored acorns are never retrieved by the rodents. Those acorns that are not retrieved have a chance to germinate and establish into a new tree. Thus, the interaction between mice and oaks is potentially mutualistic. However, the interaction is only mutualistic when the acorns are placed in locations where germination is likely to take place. The aim of this study was to investigate whether and how the strategy of hoarding (i.e. storing the seeds) depended on the presence of wild boar (who are very fond of acorns too!), de abundance of acorns and the abundance of mice in the area. Wild boar did not seem to be very capable to detect the acorns that had been hidden in the soil by the rodents, and as a consequence they seem to have little effect on the hoarding strategy of rodents. The abundance of rodents and of acorns does affect the hoarding patterns of rodents. With more competition (i.e. more mice or fewer acorns), seeds are hidden more quickly and are being scattered more widely. The acorns benefit from this, as their chance to survive and successfully establish as a new tree increases with dispersal distance and seed spacing.
Muizen leggen een wintervoorraad aan van eikels, maar een deel van deze voorraad wordt vaak niet opgegeten door de muizen. De niet opgegeten eikels hebben een kans om zich te vestigen als nieuwe eik, en daarmee is de interactie tussen muizen en eiken in potentie een mutualisme. Echter, er is alleen sprake van een mutualisme als de eikels op goede kiemplaatsen terecht komen. Doel van deze studie was te onderzoeken of de verstopstrategie van muizen afhankelijk was de aanwezigheid van wilde zwijnen (die ook dol op eikels zijn!), van het aanbod aan eikels, en van het aantal muizen in het gebied. De wilde zwijnen lijken niet goed in staat te zijn om de door muizen in de grond verstopte eikels terug te vinden, en daardoor hebben zij weinig invloed op het hamstergedrag van de muizen. Het aantal eikels en muizen heeft wel invloed op de verstopstrategie. Hoe meer concurrentie (dus, meer muizen of juist minder eikels), hoe sneller en meer verspreid de zaden verstopt worden. De eikels profiteren daar van, want hoe beter ze verspreid worden des te groter hun overlevingskans.
Plant movements and climate warming: intraspecific variation in growth responses to nonlocal soils
Frenne, P. De; Coomes, D. ; Schrijver, A. De; Staelens, J. ; Alexander, J.M. ; Bernhardt-Romermann, M. ; Brunet, J. ; Chabrerie, O. ; Chiarucci, A. ; Ouden, J. den - \ 2014
New Phytologist 202 (2014)2. - ISSN 0028-646X - p. 431 - 441.
local adaptation - latitudinal gradient - vascular plants - forest herbs - nitrogen deposition - seed dispersal - range shifts - germination - colonization - temperature
Most range shift predictions focus on the dispersal phase of the colonization process. Because moving populations experience increasingly dissimilar nonclimatic environmental conditions as they track climate warming, it is also critical to test how individuals originating from contrasting thermal environments can establish in nonlocal sites. We assess the intraspecific variation in growth responses to nonlocal soils by planting a widespread grass of deciduous forests (Milium effusum) into an experimental common garden using combinations of seeds and soil sampled in 22 sites across its distributional range, and reflecting movement scenarios of up to 1600 km. Furthermore, to determine temperature and forest-structural effects, the plants and soils were experimentally warmed and shaded. We found significantly positive effects of the difference between the temperature of the sites of seed and soil collection on growth and seedling emergence rates. Migrant plants might thus encounter increasingly favourable soil conditions while tracking the isotherms towards currently ‘colder’ soils. These effects persisted under experimental warming. Rising temperatures and light availability generally enhanced plant performance. Our results suggest that abiotic and biotic soil characteristics can shape climate change-driven plant movements by affecting growth of nonlocal migrants, a mechanism which should be integrated into predictions of future range shifts.
Forage patch use by grazing herbivores in a South African grazing ecosystem
Venter, J.A. ; Nabe-Nielsen, J. ; Prins, H.H.T. ; Slotow, R. - \ 2014
Acta Theriologica 59 (2014)3. - ISSN 0001-7051 - p. 457 - 466.
predation risk - heterogeneous pastures - antipredator response - distribution patterns - behavioral-responses - habitat selection - seed dispersal - burned patches - wolf predation - elk
Understanding how different herbivores make forage patch use choices explains how they maintain an adequate nutritional status, which is important for effective conservation management of grazing ecosystems. Using telemetry data, we investigated nonruminant zebra (Equus burchelli) and ruminant red hartebeest (Alcelaphus buselaphus subspecies camaa), use of burnt patches in a landscape mosaic of nutrient-poor, old grassland interspersed with young, recently burnt, nutrient-rich grass patches. The Mkambati Nature Reserve landscape on the east coast of South Africa provided large grazers with a challenge in finding and using appropriate patches in which to forage to meet their nutritional requirements. In Mkambati, grassland fires, mostly ignited by poachers, induce regrowth of young nutrient-rich grass, which subsequently attract grazers. We tested if the study animals foraged more in burnt patches than in the unburned grassland and whether burnt patch use was related to the distance to the previously visited burnt patch, burnt patch size, burnt patch age, and distance to areas with high poaching risk using MANOVA. In general, zebra moved faster than red hartebeest, and both species moved faster in unburnt grassland than in burnt patches. Red hartebeest and zebra patch selection were influenced by interpatch distance, patch age, patch size, and poaching risk. A limited set of intrinsic traits, i.e., body mass, digestion strategy, and muzzle width, yielded different patch use rules for the two species. Large ungulates patch use behaviour varied among species and across conditions and was influenced by anthropogenic impacts such as poaching and changed fire regimes. This could potentially affect biodiversity negatively and needs to be factored into management of conservation areas.
Tropical secondary forest management influences frugivorous bat composition, abundance and fruit consumption in Chiapas, Mexico
Vleut, I. ; Levy-Tacher, S.I. ; Boer, W.F. de; Galindo-Gonzalez, J. - \ 2013
PLoS ONE 8 (2013)10. - ISSN 1932-6203
rain-forest - community structure - neotropical forest - foraging habitat - scattered trees - seed dispersal - eating bats - succession - vegetation - diversity
Most studies on frugivorous bat assemblages in secondary forests have concentrated on differences among successional stages, and have disregarded the effect of forest management. Secondary forest management practices alter the vegetation structure and fruit availability, important factors associated with differences in frugivorous bat assemblage structure, and fruit consumption and can therefore modify forest succession. Our objective was to elucidate factors (forest structural variables and fruit availability) determining bat diversity, abundance, composition and species-specific abundance of bats in (i) secondary forests managed by Lacandon farmers dominated by Ochroma pyramidale, in (ii) secondary forests without management, and in (iii) mature rain forests in Chiapas, Southern Mexico. Frugivorous bat species diversity (Shannon H’) was similar between forest types. However, bat abundance was highest in rain forest and O. pyramidale forests. Bat species composition was different among forest types with more Carollia sowelli and Sturnira lilium captures in O. pyramidale forests. Overall, bat fruit consumption was dominated by early-successional shrubs, highest late-successional fruit consumption was found in rain forests and more bats consumed early-successional shrub fruits in O. pyramidale forests. Ochroma pyramidale forests presented a higher canopy openness, tree height, lower tree density and diversity of fruit than secondary forests. Tree density and canopy openness were negatively correlated with bat species diversity and bat abundance, but bat abundance increased with fruit abundance and tree height. Hence, secondary forest management alters forests’ structural characteristics and resource availability, and shapes the frugivorous bat community structure, and thereby the fruit consumption by bats
Inter-and intraspecific variation in fern mating systems after long-distance colonization: the importance of selfing
Groot, G.A. de; Verduyn, B. ; Wubs, E.R.J. ; Erkens, R.H.J. - \ 2012
BMC Plant Biology 12 (2012). - ISSN 1471-2229 - 13 p.
genetic load - inbreeding depression - reproductive-biology - population-structure - homosporous ferns - blechnum-spicant - osmunda-regalis - seed dispersal - plants - fertilization
Background: Previous studies on the reproductive biology of ferns showed that mating strategies vary among species, and that polyploid species often show higher capacity for self-fertilization than diploid species. However, the amount of intraspecific variation in mating strategy and selfing capacity has only been assessed for a few species. Yet, such variation may have important consequences during colonization, as the establishment of any selfing genotypes may be favoured after long-distance dispersal (an idea known as Baker’s law). Results: We examined intra-and interspecific variation in potential for self-fertilization among four rare fern species, of which two were diploids and two were tetraploids: Asplenium scolopendrium (2n), Asplenium trichomanes subsp. quadrivalens (4n), Polystichum setiferum (2n) and Polystichum aculeatum (4n). Sporophyte production was tested at different levels of inbreeding, by culturing gametophytes in isolation, as well as in paired cultures with a genetically different gametophyte. We tested gametophytes derived from various genetically different sporophytes from populations in a recently planted forest colonized through long-distance dispersal (Kuinderbos, the Netherlands), as well as from older, less disjunct populations. Sporophyte production in isolation was high for Kuinderbos genotypes of all four species. Selfing capacity did not differ significantly between diploids and polyploids, nor between species in general. Rather selfing capacity differed between genotypes within species. Intraspecific variation in mating system was found in all four species. In two species one genotype from the Kuinderbos showed enhanced sporophyte production in paired cultures. For the other species, including a renowned out crosser, selfing capacity was consistently high. Conclusions: Our results for four different species suggest that intraspecific variation in mating system may be common, at least among temperate calcicole ferns, and that genotypes with high selfing capacity may be present among polyploid as well as diploid ferns. The surprisingly high selfing capacity of all genotypes obtained from the Kuinderbos populations might be due to the isolated position of these populations. These populations may have established through single-spore colonization, which is only possible for genotypes capable of self-fertilization. Our results therewith support the idea that selection for selfing genotypes may occur during long-distance colonization, even in normally outcrossing, diploid ferns
Distorted-distance models for directional dispersal: a general framework with application to a wind-dispersed tree
Putten, B. van; Visser, M.D. ; Muller-Landau, H.C. ; Jansen, P.A. - \ 2012
Methods in Ecology and Evolution 3 (2012)4. - ISSN 2041-210X - p. 642 - 652.
seed dispersal - pollen dispersal - recruitment limitation - anisotropic dispersal - mechanistic models - patterns - environments - forests - identification - consequences
1. Seed and pollen dispersal is often directionally biased, because of the inherent directionality of wind and many other dispersal vectors. Nevertheless, the vast majority of studies of seed and pollen dispersal fit isotropic dispersal kernels to data, implicitly assuming that dispersal is equally likely in all directions. 2. Here, we offer a flexible method for stochastic modelling of directional dispersal data. We show how anisotropic models can be constructed by combining standard dispersal functions with ‘distorted- distance functions’ that transform the circular contour lines of any isotropic dispersal kernel into non-circular shapes. Many existing anisotropic phenomenological models of seed and pollen dispersal are special cases of our framework. 3. We present functional forms for the specific case of elliptic distorted-distance functions, under which contour lines of the seed shadow become non-concentric, nested ellipses, and show how models using these functions can be constructed and parameterized. R-code is provided. 4. We applied the elliptic anisotropic models to characterize seed dispersal in the wind-dispersed Neotropical tree Luehea seemannii (Malvaceae) on Barro Colorado Island, Panama. We used inverse modelling to fit alternative models to data of seed rain into seed traps, the locations of seed traps and adult trees, and tree size. 5. Our anisotropic model performed considerably better than commonly applied isotropic models, revealing that seed dispersal of L. seemannii was strongly directional. The best-fitting model combined a 3-parameter elliptic distorted-distance function that captured the strong directional biases with a 1-parameter exponential dispersal kernel, a 1-parameter negative binomial probability distribution describing the clumping of seed rain and a 1-parameter function relating tree fecundity to tree diameter. 6. The framework presented in this paper enables more flexible and accurate modelling of directional dispersal data. It is applicable not only to studies of seed dispersal, but also to a wide range of other problems in which large numbers of particles disperse fromone or more point sources.
Comparison of pollen gene flow among four European beech (Fagus sylvatica L.) populations characterized by different management regimes
Piotti, A. ; Leonardi, S. ; Buiteveld, J. ; Geburek, T. ; Gerber, S. ; Kramer, K. ; Vettori, C. ; Vendramin, G.G. - \ 2012
Heredity 108 (2012). - ISSN 0018-067X - p. 322 - 331.
pinus-sylvestris l. - paternity analysis - parentage analysis - mating patterns - silvicultural practices - microsatellite markers - habitat fragmentation - plant-populations - sorbus-torminalis - seed dispersal
The study of the dispersal capability of a species can provide essential information for the management and conservation of its genetic variability. Comparison of gene flow rates among populations characterized by different management and evolutionary histories allows one to decipher the role of factors such as isolation and tree density on gene movements. We used two paternity analysis approaches and different strategies to handle the possible presence of genotyping errors to obtain robust estimates of pollen flow in four European beech (Fagus sylvatica L.) populations from Austria and France. In each country one of the two plots is located in an unmanaged forest; the other plots are managed with a shelterwood system and inside a colonization area (in Austria and France, respectively). The two paternity analysis approaches provided almost identical estimates of gene flow. In general, we found high pollen immigration (~75% of pollen from outside), with the exception of the plot from a highly isolated forest remnant (~50%). In the two unmanaged plots, the average within-population pollen dispersal distances (from 80 to 184¿m) were higher than previously estimated for beech. From the comparison between the Austrian managed and unmanaged plots, that are only 500¿m apart, we found no evidence that either gene flow or reproductive success distributions were significantly altered by forest management. The investigated phenotypic traits (crown area, height, diameter and flowering phenology) were not significantly related with male reproductive success. Shelterwood seems to have an effect on the distribution of within-population pollen dispersal distances. In the managed plot, pollen dispersal distances were shorter, possibly because adult tree density is three-fold (163 versus 57 trees per hectare) with respect to the unmanaged one
Het plantendispersiemodel DIMO; verbetering van de modellering in de Natuurplanner
Wamelink, G.W.W. ; Jochem, R. ; Greft-van Rossum, J.G.M. van der; Grashof-Bokdam, C.J. ; Wegman, R.M.A. ; Franke, G.J. ; Prins, A.H. - \ 2011
Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-werkdocument 241)
vegetatie - zaadverspreiding - verspreiding van planten - zaadbanken - landgebruik - klimaatverandering - natuurgebieden - modellen - vegetation - seed dispersal - plant dispersal - seed banks - land use - climatic change - natural areas - models
Verandering van landgebruik en de daaruit voortvloeiende versnippering maken de dispersie van soorten die afhankelijk zijn van natuurgebieden moeilijker. Daarbij komt dat als gevolg van klimaatverandering dispersie van plantensoorten belangrijker wordt. Om de effecten van deze veranderingen te kunnen inschatten op landelijke en later Europese schaal is het plantendispersiemodel DIMO ontwikkeld. Op basis van dispersiekenmerken voor wind, water en dierlijke dispersie, zaadbank en huidige voorkomen wordt de verspreiding van zaden en de vestiging van soorten op gridbasis gemodelleerd. Het model is gevalideerd voor de exoot Tengere rus (Juncus tenuis). Sinds de introductie in 1825 heeft deze soort zich vanuit drie punten over Nederland uitgebreid. Het model was goed in staat deze kolonisatie te simuleren. De verspreiding van de soort gebaseerd op waarnemingen sinds 1950 tot aan heden loopt ongeveer tien jaar voor op de modelsimulaties. Een belangrijk onderdeel dat nog mist in het model is het effect van waterdispersie. Hieraan wordt verder gewerkt.
Is spatial structure the key to promote plant diversity in Mediterranean forets plantations?
González-Moreno, P. ; Quero, J.L. ; Poorter, L. ; Bonet, F.J. ; Zamora, R. - \ 2011
Basic and Applied Ecology 12 (2011)3. - ISSN 1439-1791 - p. 251 - 259.
pine plantations - seed dispersal - fragments - restoration - recruitment - vegetation - patterns - distance - spain - edge
Mediterranean forest plantations are currently under an intense debate related to their ecological function, sustainability and future performance. In several Mediterranean countries, efforts are directed to convert pine plantations into mixed and more diverse forests. This research aims to evaluate the effect of the spatial configuration of pine plantations on regeneration and plant diversity in order to facilitate plantation management towards more diversified stands. Spatial characteristics of plantations (proximity to different vegetation types, fragmentation and internal patch structure) were related to abundance of seedlings of an ecologically important broadleaved species, Holm Oak (Quercus ilex L.), and the Shannon diversity index of the community. Q. ilex seedling abundance and plant diversity in pine plantation patches are favoured by the proximity to oak patches located uphill. Fragmentation affected only plant diversity, with smaller patches having more diversity. The internal structure of the pine patch influenced both regeneration of Q. ilex and diversity. Pine patches with lower pine tree density were characterized by higher diversity and less Q. ilex regeneration confirming that internal structure affects species differently. From a management perspective, the process of conversion of Mediterranean pine plantations to mixed oak–pine forests could be facilitated by (1) having the seed source uphill from the plantation, (2) increasing the fragmentation of plantations and (3) promoting the internal heterogeneity of plantations to create a diverse range of light environments matching the different requirements of species
Spatial variation in ditch bank plant species composition at the regional level: the role of environment and dispersal
Leng, X. ; Musters, C.J.M. ; Snoo, G.R. de - \ 2010
Journal of Vegetation Science 21 (2010)5. - ISSN 1100-9233 - p. 868 - 875.
seed dispersal - beta-diversity - similarity - distance - conservation - patterns - ecology - communities - biodiversity - forests
Questions: Can patterns of species similarity on ditch banks be explained by environmental and dispersal factors and, if so, to what extent? Does the pattern of distance decay differ among different species groups (all species versus target species of conservation interest; species of different dispersal type)? Location: Krimpenerwaard, the Netherlands. Methods: In 2006-2007, ditch bank vegetation data on 130 terrestrial herbaceous species were collected on 72 plots. Species similarity was measured and related to environmental distance (soil type and nutrient level) and dispersal distance (geographic distance and limitation of dispersal by water, wind and agricultural activities) as explanatory factors using multiple regression on distance matrices (MRM). Differences in rates of distance decay in species similarity among different subsets of data (species groups) were investigated using randomization tests. Results: In all species, patterns of similarity of composition are influenced mainly by variations in dispersal, while for target species these are due to combined effects of environmental and dispersal variation. Compared with species using other dispersal mechanisms, water-dispersed species had half the rate of distance decay. Conclusions: For all species considered here, dispersal limitation seems more responsible for the spatial variation in species composition than environmental determinism. Conservation management focused on plant species diversity would be more successful in areas adjacent to those where a similar management regime is already in force. For target species of conservation interest, besides dispersal limitation, environmental determinants like nutrient level are also important. As a means of conserving such target species, therefore, focusing on reducing nutrient levels and facilitating species dispersal will be more effective than current management practices, which mainly focus on reducing fertilizer inputs.
Modeling the Spatial Distribution and Fruiting Pattern of a Key Tree Species in a Neotropical Forest: Methodology and Potential Applications
Caillaud, D. ; Crofoot, M.C. ; Scarpino, S.V. ; Jansen, P.A. ; Garzon-Lopez, C.X. ; Winkelhagen, A.J.S. ; Bohlman, S.A. ; Walsh, P.D. - \ 2010
PLoS ONE 5 (2010)11. - ISSN 1932-6203 - 10 p.
approximate bayesian computation - dipteryx-panamensis - movement patterns - habitat selection - tropical forest - seed dispersal - el-nino - behavior - panama - recruitment
Background - The movement patterns of wild animals depend crucially on the spatial and temporal availability of resources in their habitat. To date, most attempts to model this relationship were forced to rely on simplified assumptions about the spatiotemporal distribution of food resources. Here we demonstrate how advances in statistics permit the combination of sparse ground sampling with remote sensing imagery to generate biological relevant, spatially and temporally explicit distributions of food resources. We illustrate our procedure by creating a detailed simulation model of fruit production patterns for Dipteryx oleifera, a keystone tree species, on Barro Colorado Island (BCI), Panama. Methodology and Principal Findings - Aerial photographs providing GPS positions for large, canopy trees, the complete census of a 50-ha and 25-ha area, diameter at breast height data from haphazardly sampled trees and long-term phenology data from six trees were used to fit 1) a point process model of tree spatial distribution and 2) a generalized linear mixed-effect model of temporal variation of fruit production. The fitted parameters from these models are then used to create a stochastic simulation model which incorporates spatio-temporal variations of D. oleifera fruit availability on BCI. Conclusions and Significance - We present a framework that can provide a statistical characterization of the habitat that can be included in agent-based models of animal movements. When environmental heterogeneity cannot be exhaustively mapped, this approach can be a powerful alternative. The results of our model on the spatio-temporal variation in D. oleifera fruit availability will be used to understand behavioral and movement patterns of several species on BCI.
Modelling small-scale dispersal of the Great Reed Warbler Acrocephalus arundinaceus in a fragmented landscape
Bosschieter, L. ; Goedhart, P.W. ; Foppen, R.P.B. ; Vos, C.C. - \ 2010
Ardea 98 (2010). - ISSN 0373-2266 - p. 383 - 394.
gap crossing decisions - breeding dispersal - metapopulation dynamics - agricultural landscape - seed dispersal - forest birds - habitat - conservation - movement - consequences
We studied dispersal of Great Reed Warblers Acrocephalus arundinaceus, using a mark–resight model for dispersal. We assessed the relevance of ecological distance, defined as movement along reed edges, as opposed to straight line distance for predicting the distribution of dispersal. In a mark–resight study in the northern Netherlands, 1158 birds were ringed. 178 birds were resighted at least once, with 254 movements between known nesting locations in successive years. Dispersal was defined as movement between successive nesting sites, and modelled as an exponential function of ecological and geographical distances. To correctly model dispersal probabilities in the fragmented study area, the model discriminates between suitable habitat sections and intermediate gaps. Several nested models for dispersal were compared by means of the likelihood ratio test. Models incorporating ecological distance gave a better fit than models using geographical distance, although the difference was not large. To describe dispersal probabilities, combined models were necessary at both local and long distance scales, and separate models were needed for juveniles and adults. For a landscape without gaps, the parameter estimates of the best model can be interpreted as follows. An estimated 65% of the adult dispersal distances were within a close range of the previous nesting location with a mean ecological dispersal distance of 0.58 km. The remaining 35% had an estimated mean distance of 10.3 km. An estimated 39% of the juvenile movements were random over the study area. The remaining 61% had a mean dispersal distance of 3.1 km. These results suggest that there might be two dispersal strategies in the Great Reed Warbler. There is also an indication that adults disperse further when connectivity decreases. These findings indicate that dispersal of Great Reed Warblers is not random, but smaller dispersal distances are more likely than larger distances. This might result in a limited dispersal ability of the species over the fragmented landscape.
Weinig gevaar van distelzaad
Zeeland, M.G. van; Hoek, H. - \ 2010
Akker magazine 2010 (2010)10. - ISSN 1875-9688 - p. 19 - 19.
onkruiden - cirsium arvense - verspreiding van planten - zaadverspreiding - onkruidbestrijding - weeds - cirsium arvense - plant dispersal - seed dispersal - weed control
Telers zijn zeer beducht op de verspreiding van akkerdistelzaad uit natuurgebieden, omdat ze bang zijn voor veronkruiding van percelen. Toch blijkt deze verspreiding erg mee te vallen, zo blijkt uit veldproeven van PPO-AGV en PRI.
Identifying and prioritising services in European terrestrial and freshwater ecosystems
Harrison, P.A. ; Vandewalle, M. ; Sykes, M.T. ; Berry, P.M. ; Bugter, R.J.F. ; Bello, F. de; Feld, C.K. ; Grandin, U. ; Harrington, R. ; Haslett, J.R. ; Jongman, R.H.G. ; Luck, G.W. ; Martins da Silva, P. ; Moora, M. ; Settele, J. ; Sousa, J.P. ; Zobel, M. - \ 2010
Biodiversity and Conservation 19 (2010). - ISSN 0960-3115 - p. 2791 - 2821.
land-use - climate-change - agricultural landscapes - calcareous grasslands - species-diversity - seed dispersal - long-term - information-systems - vegetation dynamics - economic valuation
Ecosystems are multifunctional and provide humanity with a broad array of vital services. Effective management of services requires an improved evidence base, identifying the role of ecosystems in delivering multiple services, which can assist policy-makers in maintaining them. Here, information from the literature and scientific experts was used to systematically document the importance of services and identify trends in their use and status over time for the main terrestrial and freshwater ecosystems in Europe. The results from this review show that intensively managed ecosystems contribute mostly to vital provisioning services (e.g. agro-ecosystems provide food via crops and livestock, and forests provide wood), while semi-natural ecosystems (e.g. grasslands and mountains) are key contributors of genetic resources and cultural services (e.g. aesthetic values and sense of place). The most recent European trends in human use of services show increases in demand for crops from agro-ecosystems, timber from forests, water flow regulation from rivers, wetlands and mountains, and recreation and ecotourism in most ecosystems, but decreases in livestock production, freshwater capture fisheries, wild foods and virtually all services associated with ecosystems which have considerably decreased in area (e.g. semi-natural grasslands). The condition of the majority of services show either a degraded or mixed status across Europe with the exception of recent enhancements in timber production in forests and mountains, freshwater provision, water/erosion/natural hazard regulation and recreation/ecotourism in mountains, and climate regulation in forests. Key gaps in knowledge were evident for certain services across all ecosystems, including the provision of biochemicals and natural medicines, genetic resources and the regulating services of seed dispersal, pest/disease regulation and invasion resistance.
Prunus serotina unleashed: invader dominance after 70 years of forest development
Vanhellemont, M. ; Wauters, L. ; Baeten, L. ; Bijlsma, R.J. ; Frenne, P. De; Hermy, M. ; Verheyen, K. - \ 2010
Biological Invasions 12 (2010)5. - ISSN 1387-3547 - p. 1113 - 1124.
black-cherry - propagule pressure - agricultural landscape - biotic invasions - tropical forests - spatial-patterns - acer-platanoides - seed dispersal - tree - temperate
Propagule pressure and disturbance have both been found to facilitate invasion. Therefore, knowledge on the history of introduction and disturbance is vital for understanding an invasion process, and research should focus on areas in which the invasive species has not been deliberately introduced or managed to study unconfounded colonization patterns. Comparing the outcome of such spontaneous colonization processes for different ecosystems might provide a useful framework for setting management priorities for invasive species that enter new, uninvaded areas. We focused on the 70-year spontaneous spread of the invasive tree species Prunus serotina in a pine forest in the Netherlands. To reconstruct the invasion pattern, we combined historical maps, tree ring analysis, spatially explicit tree inventory data, seed density data, and regeneration data for both native and non-native species. Prunus serotina was the only species that showed successful regeneration: the species was present throughout the forest in the tree, shrub, and herb layer. Native species were not able to outgrow the seedling stage. Our data demonstrate that P. serotina is a gap-dependent species with high seed production that builds up a seedling bank. We also compared the results of this study with a similar study on P. serotina colonization in a deciduous forest in Belgium, where P. serotina invasion was not successful. The sharp contrast between the outcomes of the two invasion processes shows the importance of studying an invasive species and the recipient ecosystem jointly and made us raise the hypothesis that herbivore pressure may facilitate P. serotina invasion
Travelling to a former sea floor: colonization of forests by understorey plant species on land recently reclaimed from the sea
Pierik, M. ; Ruijven, J. van; Bezemer, T.M. ; Berendse, F. - \ 2010
Journal of Vegetation Science 21 (2010)1. - ISSN 1100-9233 - p. 167 - 176.
bosecologie - habitatfragmentatie - plantenkolonisatie - klimaatverandering - flevoland - forest ecology - habitat fragmentation - plant colonization - climatic change - flevoland - central new-york - seed dispersal - agricultural landscape - relative importance - potential impact - vascular plants - climate-change - woodlands - migration
Questions: What are important forest characteristics determining colonization of forest patches by forest understorey species? Location: Planted forests on land recently reclaimed from the sea, the Netherlands. Methods: We related the distribution of forest specialist species in the understorey of 55 forests in Dutch IJsselmeer polders to the following forest characteristics: age, area, connectivity, distance to mainland (as a proxy for distance to seed source) and path density. We used species of the Fraxino-Ulmetum association for the Netherlands as reference for species that could potentially occur in the study area. Results: Area and age of the surveyed forests explained a large part of the variation in overall species composition and species number of forest plant species. The importance of connectivity and distance to the mainland of forest habitats became apparent only at a more detailed level of dispersal groups and individual species. The importance of forest parameters differed between dispersal groups and also between individual species. After 60 years, 75% of the potential pool of wind-dispersed species has reached the polders, whereas this was only 50% for species lacking specific adaptations to long-distance dispersal. However, the average percentage of successful colonizing species present per forest was substantially lower, ranging from 15 to 37%. Conclusions: The data strongly suggest that the colonization process in polder forests is still in its initial phase, during which easily dispersed species dominate the vegetation. Colonization success of common species that lack adaptations to long-distance dispersal is affected by spatial configuration of the forests, and most rare species that could potentially occur in these forests are still absent. Implications for conservation of rare species in fragmented landscapes are discussed
DIMO 184.108.40.206 manual
Malinowska, A.H. ; Greft-van Rossum, J.G.M. van der; Wamelink, G.W.W. - \ 2009
Wageningen : Alterra (Alterra-rapport 1821) - 25
verspreiding van planten - zaadverspreiding - degradatie - kieming - modellen - plant dispersal - seed dispersal - degradation - germination - models
DIMO 220.127.116.11 is a plant dispersal model. It simulates plant dispersal in time, given (abiotic) suitability and species-specific characteristics. DIMO comprises three main processes: seed dispersal, seed-bank degradation and germination. The Manual for DIMO 18.104.22.168 consists of instructions on how to install the program, prepare the input data, run the model and uninstall the program.
Establishment limitation of holm oak (Quercus ilex subsp. Ballota (Desf.) Samp.) in a Mediterranean savanna - forest ecosystem
Smit, C. ; Díaz, M. ; Jansen, P.A. - \ 2009
Annals of Forest Science 66 (2009)5. - ISSN 1286-4560 - p. 511p1 - 511p7.
spatial-patterns - seed dispersal - food - regeneration - recruitment - rodents - shrubs - acorns - landscape - pilferage
¿Tree recruitment in Mediterranean savannas is generally hampered, in contrast with the original oak forests where these savannas are derived from. We asked whether this difference in recruitment success can be explained by differential post-dispersal survival. For one year we monitored experimentally cached holm oak acorns in a savanna ¿ forest ecosystem in Central Spain, and recorded cache pilferage, type of pilferer, boar rooting, seedling emergence, seedling survival and the cause of mortality. ¿Cache pilferage was significantly lower in savanna (8%) than in forest (21%). However, the higher cache survival was more than offset by lower seedling emergence and, particularly, by nine times higher seedling mortality in savanna, mainly due to desiccation. Wild boar rooting did not differ between experimental caches and controls without acorns, indicating that individual cached acorns do not trigger rooting activity. ¿Our results indicate that the difference in post-dispersal survival between savanna and forest is due to lower emergence and, primarily, higher seedling mortality in savanna, not to higher cache pilferage. Absence of safe sites such as shrubs, abundantly present in the forest, may well explain the lack of recruitment in the savanna. Management measures appear necessary for long-term persistence of Mediterranean savannas in general
Darwin's wind hypothesis: does it work for plant dispersal in fragmented habitats?
Riba, M. ; Mayol, M. ; Giles, B.E. ; Ronce, O. ; Imbert, E. ; Velde, M. van der; Chauvet, S. ; Ericson, L. ; Bijlsma, R. ; Vosman, B. ; Smulders, M.J.M. ; Olivieri, I. - \ 2009
New Phytologist 183 (2009)3. - ISSN 0028-646X - p. 667 - 677.
habitatfragmentatie - plantenecologie - klimaatverandering - windeffecten - habitat fragmentation - plant ecology - climatic change - wind effects - seed dispersal - centaurea-corymbosa - island populations - mycelis-muralis - crepis-sancta - gene flow - evolution - metapopulation - range - strategies
• Using the wind-dispersed plant Mycelis muralis, we examined how landscape fragmentation affects variation in seed traits contributing to dispersal. • Inverse terminal velocity (V(t)¯¹) of field-collected achenes was used as a proxy for individual seed dispersal ability. We related this measure to different metrics of landscape connectivity, at two spatial scales: in a detailed analysis of eight landscapes in Spain and along a latitudinal gradient using 29 landscapes across three European regions. • In the highly patchy Spanish landscapes, seed V(t)¯¹ increased significantly with increasing connectivity. A common garden experiment suggested that differences in V(t)¯¹ may be in part genetically based. The V(t)¯¹ was also found to increase with landscape occupancy, a coarser measure of connectivity, on a much broader (European) scale. Finally, V(t)¯¹ was found to increase along a south–north latitudinal gradient. • Our results for M. muralis are consistent with 'Darwin's wind dispersal hypothesis' that high cost of dispersal may select for lower dispersal ability in fragmented landscapes, as well as with the 'leading edge hypothesis' that most recently colonized populations harbour more dispersive phenotypes.