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opencc-zeroDec 2013View details →

Data from: Hydrology, shore morphology and species traits affect seed dispersal, germination and community assembly in shoreline plant communities

1.Seed dispersal and germination are two primary processes influencing plant community assembly. On freshwater shores, water levels regulate both processes. However, it is still unclear how water levels, shore morphology and species traits interactively affect seed dispersal and germination, and how these interactions determine plant community assembly. We hypothesize that a drawdown water regime enhances seed establishment compared to a year-round stable water level, that this increases species richness and diversity, and that this is modulated by species traits and shore morphology. 2.Germination of 20 wetland plant species with different dispersal capacities (floating capacity expressed as seed floatation half-time) and soil moisture preferences for germination (Ellenberg F) was tested on artificial shores in 24 outdoor ponds in 2 complementary experiments over 8 weeks. The "dispersal experiment" tested the effect of water regime on recruitment of hydrochorously dispersing seeds. The "seed bank experiment" tested the effect of water regime on germination from a sown seed bank, on steep and gradual shores. 3.In the dispersal experiment, the drawdown regime increased recruitment and species richness. Longer floating species colonised a larger shoreline section. Soil moisture preference for germination did not determine colonisation patterns. 4.In the seed bank experiment, the drawdown regime increased the number of seedlings on gradual sloping shores, but not on steep shores. The number of germinating seedlings corresponded to the area subjected to the drawdown regime in both shore types. Species richness was not affected by water regime or shore morphology, and species traits did not determine shoreline colonisation. Most seeds germinated in moist soil conditions for all species. 5.Synthesis. A spring drawdown instead of stable water regime stimulates establishment of hydrochorously dispersing seeds in temperate wetlands, leading to higher species richness and diversity. Germination from the seed bank is more affected by water regime and shore surface than by the tested species traits. Species traits, water levels and shore morphology together determine wetland plant community assembly, with dispersal as the main driver of seedling community diversity. Water level regulations and shore morphology can be used to influence plant communities in wetland restoration.

opencc-zeroDec 2016View details →

Data from: White-tailed deer as the last megafauna dispersing seeds in Neotropical dry forests: the role of fruit and seed traits

Endozoochory is a prominent form of seed dispersal in tropical dry forests. Most extant megafauna that perform such seed dispersal are ungulates, which can also be seed predators. White-tailed deer (Odocoileus virginianus) is one of the last extant megafauna of Neotropical dry forests, but whether it serves as a legitimate seed disperser is poorly understood. We studied seed dispersal patterns and germination after white-tailed deer gut passage in a tropical dry forest in southwest Ecuador. Over 23 mo, we recorded ca 2000 seeds of 11 species in 385 fecal samples. Most seeds belonged to four species of Fabaceae: Chloroleucon mangense, Senna mollissima, Piptadenia flava, and Caesalpinia glabrata. Seeds from eight of the 11 species dispersed by white-tailed deer germinated under controlled conditions. Ingestion did not affect germination of C. mangense and S. mollissima, whereas C. glabrata showed reduced germination. Nevertheless, the removal of fruit pulp resulting from ingestion by white-tailed deer could have a deinhibition effect on germination due to seed release. Thus, white-tailed deer play an important role as legitimate seed dispersers of woody species formerly considered autochorous. Our results suggest that more research is needed to fully understand the ecological and evolutionary effects of the remaining extant megafauna on plant regeneration dynamics in the dry Neotropics.

opencc-zeroDec 2014View details →

Data from: Locomotion during digestion changes current estimates of seed dispersal kernels by fish

Dispersal of seeds by animals is an important mechanism regulating plant diversity, range expansions and invasions. Many birds, mammals, fish, and reptiles regularly ingest, transport and excrete viable seeds (known as endozoochory). The effectiveness of endozoochory is modelled in dispersal kernels: functions that describe seed shadows in the landscape by combining movement of animals with experimentally obtained seed retention times and survival. Currently, dispersal kernels use experimental data from resting animals, yet only moving animals disperse seeds. Although physical activity is known to affect digestive processes, little is known on how and to what extent this may influence current estimates of endozoochory. Activity may either prolong seed retention in the animal's gut (locomotion-priority mode hypothesis) or may not affect seed excretion rate (digestion-priority mode hypothesis), and may affect seed survival and germination positively or negatively. We tested how activity alters dispersal estimates in fish. We compared the seed dispersal potential of two riparian plant species (Carex acuta and C. riparia) by the common carp (Cyprinus carpio) subjected to three different activity levels: low (basal metabolic rate, BMR), medium (2×BMR), or high activity (3×BMR). Physical activity of the fish did not affect the number of intact retrieved seeds over 15 h of activity, but significantly affected seed retrieval patterns over time for both seed species. More active fish started seed excretion about 1 h later and kept excreting seeds at least 2 h longer. Effects of gut passage on germination could only be tested for C. acuta, where it reduced the percentage of germinating seeds by 22%, independent of the activity level. Seeds ingested by the fish germinated on average 3.5 days later than non-ingested control seeds. Seed retention times did not affect the timing of germination. Our results support the locomotion-priority mode hypothesis, and show that modelling dispersal kernels using parameters from inactive fish may underestimate potential dispersal distances. Because a trade-off between physical activity and digestive physiology is likely common in animals, it should be taken into account in future modelling of endozoochorous seed dispersal kernels.

opencc-zeroDec 2017View details →

Data from: Costs and benefits of non-random seed release for long distance dispersal in wind-dispersed plant species

The dispersal ability of plants is a major factor driving ecological responses to global change. In wind-dispersed plant species, non-random seed release in relation to wind speeds has been identified as a major determinant of dispersal distances. However, little information is available about the costs and benefits of non-random abscission and the consequences of timing for dispersal distances. We asked: 1) To what extent is non-random abscission able to promote long-distance dispersal and what is the effect of potentially increased pre-dispersal risk costs? 2) Which meteorological factors and respective timescales are important for maximizing dispersal? These questions were addressed by combining a mechanistic modelling approach and field data collection for herbaceous wind-dispersed species. Model optimization with a dynamic dispersal approach using measured hourly wind speed showed that plants can increase long-distance dispersal by developing a hard wind speed threshold below which no seeds are released. At the same time, increased risk costs limit the possibilities for dispersal distance gain and reduce the optimum level of the wind speed threshold, in our case (under representative Dutch meteorological conditions) to a threshold of 5-6 m s-1. The frequency and predictability (auto-correlation in time) of pre-dispersal seed-loss had a major impact on optimal non-random abscission functions and resulting dispersal distances. We observed a similar, but more gradual, bias towards higher wind speeds in six out of seven wind-dispersed species under natural conditions. This confirmed that non-random abscission exists in many species and that, under local Dutch meteorological conditions, abscission was biased towards winds exceeding 5-6 m s-1. We conclude that timing of seed release can vastly enhance dispersal distances in wind-dispersed species, but increased risk costs may greatly limit the benefits of selecting wind conditions for long-distance dispersal, leading to moderate seed abscission thresholds, depending on local meteorological conditions and disturbances.

opencc-zeroDec 2012View details →

Data from: Allometric scaling of long-distance seed dispersal by migratory birds

Migratory birds are often suggested to be important vectors for long-distance dispersal (LDD) of plant and animal propagules. The scale of such dispersal events (hundreds to thousands of kilometers) can influence landscape-level biological processes and species distributions. However, the few vector species studied and the lack of proper integration of their migratory movement in models of LDD has precluded the study of their potential as long-distance biotic dispersers. By means of a mechanistic model parameterized with empirical data, we first investigated the properties of seed dispersal curves generated by migratory birds and then analyzed the effect of bird size on model parameters and consequent seed dispersal patterns. Seed dispersal curves showed in most cases large and heavy tails, resulting in relatively frequent LDD (up to 3.5% of dispersal distances longer than 100 km). Bird size mediated trade-offs between bird movement and seed retention time that, in turn, determined seed dispersal patterns and the potential of each bird species as an LDD vector. Our modeling framework builds on a mechanistic understanding of seed dispersal by migratory birds and may thus be a useful tool to estimate the scale and frequency of bird-mediated, large-scale transport of native, invasive, and pathogenic organisms.

opencc-zeroNov 2021View details →

Lifespan, clonality and polyploidy regulate the global environmental niches of plants via seed dispersal in space and time

Global environmental niches have been considered in relation to the effectiveness of environmental management. Functional traits can explain the environmental niches of plant species at different spatial scales, from community to globe. However, the roles of seed dispersal in space and time in plant environmental niche and tolerance are not clear. Furthermore, knowledge of the regulation of plants' global environmental niches by lifespan, clonality and polyploidy remains limited. In response, the main objective of the research reported here was to explore how these factors regulate the global environmental niches of plants via seed dispersal in space and time. We obtained data on plant species' seed mass, seed dispersal ability, dormancy, lifespan, clonality and polyploidy from a variety of databases and quantified global environmental niche and tolerance based on the niche axes of climate, soil and elevation. Subsequently, we used phylogenetic generalized least square linear regression and structural equation models to assess the relationships of seed traits (i.e. seed mass, seed dispersal distance and dormancy), lifespan, clonality and polyploidy with environmental niches. We found significant relationships between seed mass, seed dispersal distance, dormancy, lifespan, clonality and polyploidy on the one hand and environmental niche and tolerance on the other, based on the axes of climate, soil and elevation. Compared with lifespan, ploidy and clonality, seed traits explained more variations in environmental niches and tolerance for plants. Importantly, we built pathways indicating that lifespan, clonality and polyploidy regulate the global environmental niche and tolerance of plants via seed mass and/or seed dispersal in space and time. Our study clearly highlights the mechanisms underlying environmental niches from different perspectives, including seed temporal-spatial dispersal, lifespan, clonality and polyploidy. Environmental niche theory may broadly support global-change-adaptation management for biodiversity conservation and ecosystem maintenance using the perspective of spatial and temporal patterns in ecology.

opencc-zeroDec 2021View details →

Seed dispersal by carnivores in temperate and tropical dry forests

The seed dispersal mechanisms and regeneration of various forest ecosystems can benefit from the actions of carnivores via endozoochory. This study aims to evaluate the role of carnivores in endozoochory and diploendozoochory, as well as their effect on seed viability, scarification, and germination in two forest ecosystems: temperate and tropical dry forest. We collected carnivore scat in the Protected Natural Area of Sierra Fría in Aguascalientes, Mexico, for two years to determine the abundance and richness of seeds dispersed by each carnivore species, through scat analysis. We assessed seed viability through optical densitometry using X-rays, analyzed seed scarification by measuring seed coat thickness using a scanning electron microscope, and evaluated seed germination in an experiment as the percentage of seeds germinated per carnivore disperser, plant species, and forest type. In the temperate forest, four plant species (but mainly Arctostaphylos pungens) were dispersed by four mammal species. The gray fox dispersed the highest average number of seeds per scat (66.8 seeds). Bobcat dispersed seeds through diploendozoochory, which was inferred from rabbit (Sylvilagus floridanus) hair detected in their scats. The tropical dry forest presented higher abundance of seeds and richness of dispersed plant species (four species) than in the temperate forest, and the coati dispersed the highest number of seeds (8639 seeds). Endozoochory and diploendozoochory did not affect viability in thick testas seeds in temperate forest and thin testas seeds in tropical dry forest. Endozoochory improved the selective germination of seeds. Nine plant species were dispersed by endozoochory, but only one species (Juniperus sp.) by diploendozoochory. These results suggest that carnivores can perform an important ecological function by dispersing a great abundance of seeds, scarifying these seeds causing the formation of holes and cracks in the testas without affecting viability and promoting the selective germination of seeds.

opencc-zeroMar 2022View details →

Avian seed dispersal may be insufficient for plants to track future temperature change on tropical mountains - data

Abstract Aim: Climate change causes species' range shifts globally. Terrestrial plant species often lag behind temperature shifts, and it is unclear to what extent animal-dispersed plants can track climate change. Here, we estimate the ability of bird-dispersed plant species to track future temperature change on a tropical mountain. Location: Tropical elevational gradient (500–3500 m a.s.l.) in the Manú biosphere reserve, Peru Time period: 1960–1990 to 2061–2080 Taxa: Fleshy-fruited plants, avian frugivores Methods: Using simulations based on the functional traits of avian frugivores and fruiting plants, we quantified the number of long-distance dispersal (LDD) events that woody plant species would require to track projected temperature shifts on a tropical mountain by the year 2070 under different greenhouse gas emission scenarios (RCP 2.6, 4.5 and 8.5). We applied this approach to 343 bird-dispersed woody plant species. Results: Our simulations reveal that bird-dispersed plants differ in their climate-tracking ability, with large-fruited and canopy plants exhibiting a higher climate-tracking ability. Our simulations also suggest that even under scenarios of strong and intermediate mitigation of greenhouse gas emissions (RCP 2.6 and 4.5), sufficient upslope dispersal would require several LDD events by 2070, which is unlikely for the majority of woody plant species. Furthermore, the ability of plant species to track future temperature changes increased in simulations with a low degree of trait matching between plants and birds, suggesting that plants in generalised seed-dispersal systems may be more resilient to climate change. Main conclusion: Our study illustrates how plant and animal functional traits can inform predictive models of species dispersal and range shifts under climate change and suggests that the biodiversity of tropical mountain ecosystems is highly vulnerable to future warming. The increasing availability of functional trait data for plants and animals globally will allow parameterisation of similar models for many other seed-dispersal systems.

opencc-zeroJul 2022View details →

Improving measurements of the falling trajectory and terminal velocity of wind-dispersed seeds

1. Seed dispersal by wind is one of the most important dispersal mechanisms in plants. The key seed trait affecting seed dispersal by wind is the effective terminal velocity (hereafter "terminal velocity", Vt), the maximum falling speed of a seed in still air. Accurate estimates of Vt are crucial for predicting intra- and interspecific variation in seed dispersal ability. However, existing methods produce biased estimates of Vt for slow- or fast-falling seeds, fragile seeds, and seeds with complex falling trajectories. 2. We present a new video-based method that estimates the falling trajectory and Vt of wind-dispersed seeds. The design involves a mirror that enables a camera to simultaneously record a falling seed from two perspectives. Automated image analysis then determines three-dimensional seed trajectories at high temporal resolution. To these trajectories, we fit a physical model of free fall with air resistance to estimate Vt. We validated this method by comparing the estimated Vt of spheres of different diameters and materials to theoretical expectations, and by comparing the estimated Vt of seeds to measurements in a vertical wind tunnel. 3. Vt estimates closely match theoretical expectations for spheres and vertical wind tunnel measurements for seeds. However, our Vt estimates for fast-falling seeds are markedly higher than those in an existing trait database. This discrepancy seems to arise because previous estimates inadequately accounted for seed acceleration. 4. The presented method yields accurate, efficient and affordable estimates of the three-dimensional falling trajectory and terminal velocity for a wide range of seed types. The method should thus advance the understanding and prediction of wind-driven seed dispersal.

opencc-zeroSep 2022View details →

Data for: Quantifying patch-specific seed dispersal and local population dynamics to estimate population spread of an endangered plant species

Dataset on seed dispersal and population spread for the paper Quantifying patch-specific seed dispersal and local population dynamics to estimate population spread of an endangered plant species Jinlei Zhu1, 2, *, Karolína Hrušková1, 3, Hana Pánková1, Zuzana Münzbergová1, 3 1Institute of Botany, Czech Academy of Sciences, Průhonice, Czech Republic 2Institute of Landscape and Plant Ecology, University of Hohenheim, Stuttgart, Germany 3Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic *Corresponding author: jinlei.zhu@uni-hohenheim.de Institute of Landscape and Plant Ecology University of Hohenheim Ottilie-Zeller-Weg 2, 70599 Stuttgart, Germany

opencc-zeroOct 2022View details →

Seed dispersal by wind decreases when plants are water-stressed, potentially counteracting species coexistence and niche evolution

Hydrology is a major environmental factor determining plant fitness, and hydrological niche segregation (HNS) has been widely used to explain species coexistence. Nevertheless, the distribution of plant species along hydrological gradients does not only depend on their hydrological niches but also on their seed dispersal, with dispersal either weakening or reinforcing the effects of HNS on coexistence. However, it is poorly understood how seed dispersal responds to hydrological conditions. To close this gap, we conducted a common-garden experiment exposing five wind-dispersed plant species (Bellis perennis, Chenopodium album, Crepis sancta, Hypochaeris glabra, and H. radicata) to different hydrological conditions. We quantified the effects of hydrological conditions on seed production and dispersal traits, and simulated seed dispersal distances with a mechanistic dispersal model. We found species-specific responses of seed production, seed dispersal traits, and predicted dispersal distances to hydrological conditions. Despite these species-specific responses, there was a general positive relationship between seed production and dispersal distance: plants growing in favourable hydrological conditions not only produce more seeds but also disperse them over longer distances. This arises mostly because plants growing in favourable environments grow taller and thus disperse their seeds over longer distances. We postulate that the positive relationship between seed production and dispersal may reduce the concentration of each species to the environments favourable for it, thus counteracting species coexistence. Moreover, the resulting asymmetrical gene flow from favourable to stressful habitats may slow down the microevolution of hydrological niches, causing evolutionary niche conservatism. Accounting for context-dependent seed dispersal should thus improve ecological and evolutionary models for the spatial dynamics of plant populations and communities.

opencc-zeroDec 2017View details →

Data from: Local extinctions of obligate frugivores and patch size reduction disrupt the structure of seed dispersal networks

A central problem in ecology is to understand how human impacts affect plant-animal interactions that lead to effective seed dispersal services for plant communities. Seed dispersal services are the outcome of plant-frugivore interactions that often form local networks of interacting species. Recent work has shown that some frugivorous bird species are more critical to network organization than others. Here, we explore how patch size and the potential local extinctions of obligate frugivorous birds affect the reorganization of seed dispersal networks. We examined the structure of 20 empirical seed dispersal networks documented across tropical avian assemblages occupying widely variable habitat patch sizes, a surrogate of the amount of remaining habitat. Networks within small forest patches consistently supported both lower plant and bird species richness. Forest patch size was positively associated with nestedness, indicating that reductions in patch size disrupted the nested organization of seed dispersal networks. Obligate frugivores, especially large-bodied species, were almost entirely absent from small forest patches. Analysis at the species level showed that obligate frugivores formed the core of interacting species, connecting species within a given seed dispersal network. Our combined results revealed that patch size reduction erodes frugivorous bird diversity, thereby affecting the integrity of seed dispersal networks. We highlight the importance of conserving large forest patches to maintain tropical forest functionality.

opencc-zeroDec 2016View details →

Data from: Neglected seed dispersers: endozoochory by Javan lutungs (Trachypithecus auratus) in Indonesia

Leaf monkeys are known to be leaf eaters, and thus, their potential role as seed dispersers has been neglected. However, they do also feed on fruits. To examine the role of leaf monkeys as endozoochorous seed dispersers, we studied the Javan lutung (Trachypithecus auratus) in Indonesia. We compared multiple aspects of seed dispersal processes (amount and diversity of seeds ingested, dispersal distance, and germination rate) of lutungs with that of the sympatric long-tailed macaque (Macaca fascicularis). Over the study period, 54 percent of the lutung feces contained intact seeds, which was equivalent to the macaque feces contained seeds (62%). Seeds of at least six plant species were detected in the lutung feces, which was less than those found in the macaque feces (>19 plant species). The main species of seeds defecated by both lutungs and macaques was Ficus spp. (seed size: 0.7 mm). Seed shadow, estimated from travel distance (range: 1–299 m) and gut passage rate (24–96 h), had a unimodal-distribution with a peak at 51–100 m, and was shorter than that reported in published accounts of macaques and other similar and smaller sized frugivores. Finally, germination rates of Ficus spp. seeds ingested by both lutungs and macaques were lower than that of the control seeds. These results imply that the dispersal effectiveness of lutungs would be lower than that of the sympatric primate frugivores. However, at a population level, lutungs could play a significant role as seed dispersers for the small-seeded species, and therefore, more research into their frugivorous habits is warranted.

Figure 4 from: Mar SS, Saunders RMK (2015) Thismia hongkongensis (Thismiaceae): a new mycoheterotrophic species from Hong Kong, China, with observations on floral visitors and seed dispersal. PhytoKeys 46: 21-33. https://doi.org/10.3897/phytokeys.46.8963

Figure 4 - Thismia hongkongensis sp. nov. (S.S. Mar 2, HK). A Entire flower. B Flower with proximal part of perianth tube removed, showing pendent stamens. C Apex of the perianth tube, showing annulus (a) and pendent stamens, with filament (f), thecae (th), lateral appendage (la), and aperture (ap) between filaments. D Longitudinal section through fused carpels. Scale bars: A, B, D = 2 mm; C = 1 mm. Drawings by Caren Pearl Shin.

Figure 2 from: Mar SS, Saunders RMK (2015) Thismia hongkongensis (Thismiaceae): a new mycoheterotrophic species from Hong Kong, China, with observations on floral visitors and seed dispersal. PhytoKeys 46: 21-33. https://doi.org/10.3897/phytokeys.46.8963

Figure 2 - Flower structure in Thismia hongkongensis sp. nov. A Mature flower, showing outer tepals (ot), inner tepals (it) and abscission zone (ab) at the base of the perianth tube. B Entire plant (S.S. Mar 1, HK). C Perianth tube with annulus (a), following removal of the proximal face of the tube, exposing pendent stamens with filament (f), thecae (th), connective (c) and lateral appendage (la) (S.S. Mar 2, HK). D Inner face of perianth tube, showing network patterning and putative nectaries (arrowed) (S.S. Mar 2, HK). Scale bars: A, D = 2 mm; B = 5 mm; C = 1 mm. Photos: A, B S.S. Mar; C, D R.M.K. Saunders.

Figure 1 from: Mar SS, Saunders RMK (2015) Thismia hongkongensis (Thismiaceae): a new mycoheterotrophic species from Hong Kong, China, with observations on floral visitors and seed dispersal. PhytoKeys 46: 21-33. https://doi.org/10.3897/phytokeys.46.8963

Figure 1 - Flower development in Thismia hongkongensis sp. nov. A, B Root system, with young flowering stalk developing (arrowed). C–H Developing flower, photographed over a 17-day period (10th, 14th, 16th, 19th, 23rd and 27th May, respectively) (S.S. Mar 1, HK). I, J Post-fertilization flower, showing abscission of perianth tube. Photos by S.S. Mar.

Figure 3 from: Mar SS, Saunders RMK (2015) Thismia hongkongensis (Thismiaceae): a new mycoheterotrophic species from Hong Kong, China, with observations on floral visitors and seed dispersal. PhytoKeys 46: 21-33. https://doi.org/10.3897/phytokeys.46.8963

Figure 3 - Fruit structure in Thismia hongkongensis sp. nov. A Flower (rear right), immature fruit, shortly after fertilization (left), and mature fruit with exposed seeds (front). B Two fruiting individuals, each with three fruits. C Lateral view of fruiting specimen, illustrating elongated fruit stalk. D Mature fruit with exposed seeds. E Dehydrated fruit. F Rehydrated fruit, after rainfall. Photos by S.S. Mar.

publicJul 2019View details →

Data from: Seed size regulates plant dispersal distances in flowing water

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publicApr 2018View details →

Data from: Costs and benefits of non-random seed release for long distance dispersal in wind-dispersed plant species

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