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The time it takes for ingested seeds to pass through the gut of animals is an important aspect of endozoochorous seed dispersal because it influences seed dispersal distance. Variations in the physical characteristics of seeds, such as their weight, volume, and specific gravity, can affect their movement through the gastrointestinal system of a given animal. We conducted feeding experiments with captive Japanese martens, Martes melampus (n = 4), at Toyama Municipal Family Park Zoo, central Japan to examine the effects of the physical characteristics of seeds on their passage times. The mean (±SD) transit time, mean retention time, and time of last appearance of four different types of commercial seeds were 2.6 ± 0.3 h (range 0.6–5.4), 9.7 ± 1.1 h (3.8–17.3), and 23.8 ± 3.1 h (12.2–51.8), respectively. All of these values are greater than those found during previous experiments conducted with mustelids. Similar to previous studies, however, none of these passage time variables was correlated with the physical characteristics of seeds. Our results thus indicate that martens disperse seeds of different plant species, whose size, volume, and specific gravity all fall within the range of those used in the present study, from parent plants at similar distances.
Various methods have been used to track seed dispersal of large-seeded species; however, the influence of different seed tracking methods on ecological outcomes of seed dispersal by animals is not well evaluated. Acorn removal by food hoarding animals and the following seedling establishment of Mongolian oak (Quercus mongolica) were investigated in Xiaoxing’anling Mountain, Heilongjiang, northeastern China, by using four different marking methods: plastic tagging, nail insertion, hole drilling, and isotope labeling. The acorn removal speed differed among marking methods, with plastic-tagged acorns being removed more slowly than those marked with nails, holes, and isotope. By checking the attached cotyledons and performing isotope analyses, more seedlings were found to establish from nailed acorns and isotope-soaked acorns than from drilled acorns and plastic-tagged acorns. Plastic-tagged acorns were transported closer than those marked with nails, holes, and isotope. Moreover, seedlings were often found clustered in caches containing acorns marked with plastic tags. Low level of cotyledon predation by animals makes it possible to directly identify focal seedlings of white oaks based on the attached cotyledons. Considering cotyledon predation by animals, coupling minor modification of cotyledons with isotope labeling appears to be an easy way to explore the actual pattern of seed dispersal of large-seeded trees, e.g., oaks.
The effectiveness of dispersers on seeds of Korean pine (Pinus koraiensis Siebold et Zuccarini) was investigated in three fragmented stands and one primary stand. The proportion of Korean pine trees was less than 7% in the fragmented stands but more than 90% in primary stand. Five estimates related seed dispersal (proportion of removed seeds, scatter-hoarded seeds, cache dynamics, dispersal distance and microhabitat) were assessed to see the effect of forest fragmentation on the probability of seed dispersal of Korean pine seeds. Our results indicated fast seed harvest of Korean pine by small rodents at the seed stations and no difference among the four stands. Scatter-hoarding rodents were potentially important in promoting natural regeneration of Korean pine as revealed by high proportion of seed removal (up to 50%), short seed lifetime from the seed release locations and lower proportion of seeds remained on the ground surface. Although a proportion of seeds were scatter-hoarded in fragmented stands, no seedling successfully established due to heavy predation. Dispersal distances were strongly left-skewed in fragmented stands, indicating that fragmentation is likely to be disadvantageous for longer distance dispersal. The effective dispersal was suffered from a very heavy cost as accompanied by a great portion of seed predation and lower level of scatter-hoarded seeds. Failing to see seedling establishment in fragmented stands rather than in primary stand indicated that fragmentation and deforestation have negative effects on dispersal behavior and consequently seed destination. Artificial tree plantation and pinecone protection are highly recommended for Korean pine regeneration.
Although the Ring Ouzel has been considered accidental in the Canary Islands, it has been observed for the last five years in the high mountain zone of Tenerife (Canary Islands), showing it to be a regular winter visitor. Its interaction with female Juniperus cedrus cones and seeds was studied by analysing its wintering diet during January-April 2008. This juniper is endemic to the Canaries and Madeira and is classified as endangered by the IUCN. Previously, its sole long-distance disperser was known to be the Raven Corvus corax, which is unfortunately now extinct in the distribution range of J. cedrus. The results show that the diet of T. torquatus in Tenerife consists mostly of female J. cedrus cones (95% of the biomass consumed). Due to the large amount of seeds dispersed by Ring Ouzels and the effectiveness in seed germination, this winter visitor constitutes an important vector in the dispersal of J. cedrus that appears to have gone undetected in the past. This passerine plays a key role in its seed dispersal system, being able to move seeds over long distances, thus connecting fragmented populations of this plant. The present work is one of the few cases described in which a plant endemic to an oceanic island is so dependent on a winter visitor, and highlights the importance of insular environments in the wintering range of the Ring Ouzel. Owing to the absence of native long-distance seed dispersers, the future fate of this conifer is now probably dependent on the wintering population of this thrush.
Anastatica hierochuntica is a monocarpic desert annual whose dry skeletons, enclosing mature fruits, often persist for a number of years. The aerial seed bank in these hygrochastic ‘resurrection plants’ therefore persists too. Life tables and fecundity schedules were constructed for A. hierochuntica populations raised under four water treatments, equivalent to 100, 200, 500 and 1000 mm rainfall. Seedling survivorship showed a Deevey type III curve for 100 mm, and a type II curve for 200 mm, while 500 and 1000 mm treatments produced Deevey type I curves. Fewer seeds germinated and seedling survivorship was lower in the low water treatments. The stage-specific mortality rate reached 0.75 under the 100 mm treatment in the seed germination stage, compared to 0.08 under the 1000 mm treatment. Increased water availability resulted in greater plant growth and reproductive output, in terms of both number of seeds per individual and reproductive value. In field studies, aerial seed banks of small plant sizeclasses (from 1 to 32 cm³) were depleted within 3-to-7 years. For the large size-classes, > 32 cm³, only a portion (79.7-44.4%) of the seeds produced were dispersed during the observational experiment (the rest remaining within the tumbleweed ball, available for subsequent germination). The projected seed bank life-time for populations raised under different water treatments increased more than fivefold (from 3 to 17 years) for the 100 mm compared to the 1000 mm rainfall treatments. Local persistence of populations was thus likely to be reduced by water stress. Populations of A. hierochuntica characterized by weak plant growth and a preponderance of small size-classes will be more vulnerable to extinction due to their low reproductive output and reduced aerial seed bank reserve.
Plant diaspore dispersal is a fundamental process affecting the development of forest vegetation and its natural regeneration, especially with regard to typical woodland species, which spread slowly and form short-term soil seed banks. Most of these species have poor seed dispersal mechanisms, which is the major cause of their very slow expansion. The following questions were asked: (i) is there a relationship between the age of a woodland and the presence of forest vascular plant species representing different seed dispersal types; (ii) how do the proportions change between species representing different seed dispersal types in relation to the age of woodland; (iii) what factors determine the presence of species representing a given seed dispersal type; (iv) which factors affect the presence and which ones influence the abundance of selected woodland species? A multiple regression models were developed based on data obtained from 144 woodland patches designated for the study. A probit regression analysis was performed for selected species exhibiting various seed dispersal models. Woodland plants of all seed dispersal types show a significant relationship with the age of woodland, starting from the strongest linkage: anemochores, myrmecochores, endozoochores, epizoochores, barochores, autochores. As the woodland ages, the proportion of forest myrmecochores and anemochores grows, whilst the proportion of autochores, epizoochores and endozoochores shrinks. Results obtained indicate that the direct proximity of ancient woodland has a major effect on the occurrence of more poorly dispersing plants in recent woodlands, such as myrmecochores and heavy anemochores.
To examine multi-annual variations in the food habits of the Japanese marten (Martes melampus), we analyzed the composition of marten feces in the Bonbori Forest Path in western Tokyo, central Japan, in two time periods a decade apart (1997–1998 and 2007–2008). The staple foods of martens in both periods were fruits/seeds and animal materials (mainly insects and mammals). The martens fed frequently on fruits/seeds and insects throughout the year in both periods, but the consumption of mammals, birds, and arthropods/other animals showed seasonal variations. The composition of fruits/seeds and the frequency of occurrence for each fruit-bearing species differed between the two periods. These results suggest that both the foraging strategy and role of martens as a seed dispersal agent changes yearly, presumably according to multi-annual variation in the availability of prey animals and/or fruits. We emphasize the importance of multi-annual studies both on food habits and to monitor food availability in the temperate region where the food environment changes among seasons, as well as years.
As the main predator and disperser of seeds, rodents play an important role in the process of vegetation regeneration by adopting different foraging and hoarding strategies in forest ecosystems. Infrared automated detection cameras and seed-tagging methods were used to understand the effects of rodents on seeds in natural environments. We chose the dominant species Apodemus peninsulae (Korean field mouse) as the focus of this study, and seeds of the three species Pinus koraiensis, Corylus mandshurica and Quercus mongolica were released and tracked in a temperate forest in northeast China. The results showed that approximately 80% of the seeds were manipulated by A. peninsulae, 15.1% of the seeds were used as food, 20.4% of the seeds were handled after feeding, 41.3% of the seeds were handled during storage, and 23.3% of the seeds remained intact. In addition, A. peninsulae preferred Q. mongolica (85.3%) and P. koraiensis (85.6%) over C. mandshurica (59.2%). The rodents frequently hoarded seeds from every species in many small, close-range, widely dispersed, single scatter-hoarded caches around the seed station. Most caches were dispersed approximately 2–4 m from the seed station. The results indicated that A. peninsulae adopted significant discriminatory processing strategies for predation, consumption, dispersal and hoarding of the different seeds of sympatric species. Seed size, proportion of kernel mass, nutrient content, and hull thickness characteristics affected the scatter-hoarding decision processes.
The recovery of species composition typical for ancient forests in recent woods is a very slow process and may last for decades or even centuries. It is enhanced only when postagricultural woods are adjacent to ancient ones. However, even in such a situation of the spatial contact of both forest types, colonization of recent woods by true forest species is a gradual process. According to studies focusing on the behaviour of individual species and their colonization rates into recent woods, it can be concluded that in more fertile habitats the migration process proceeds faster than on poorer sites. Thus, studies were conducted on light, acidic soils both in ancient and in adjoining post-agricultural pine woods (the Dicrano-Pinion Libb. 1933 alliance) and were focused on the process of the colonization of the herbaceous layer by woodland flora in recent woods. In eight transects 80 m in length perpendicular to the ancient/recent ecotone and consisting of 10 sample plots of 16 m2 laid out at intervals of 4 m, the percentage cover of herb layer species was recorded. The migration rates (based on the occurrence of the farthest individual and on the occurrence of the maximum cover of a species) for 12 forest species were calculated. The mean migration rate for all species reached 0.54 m yr–1 when based on maximum cover and 0.67 m yr–1 when based on the farthest individual and appeared to be lower than those reported in investigations in more fertile and moister habitats. The migration rates for individual species ranged from 0 to 1.21 m yr–1 and were also lower than in more fertile, black alder woodlands. The migration pattern of Vaccinium myrtillus L., the most abundant species in pine woods, fits the model based on the establishment of isolated individuals. The cover of most woodland species increased with the increasing age of a recent wood. Herb layer recovery on such sites is slower than in the more productive, fertile habitats of broadleaved forests. The ancient and recent pine woods investigated here differed in herb layer species composition despite the secondary succession having lasted for over 50–60 years.
Recent studies have demonstrated the higher likelihood of regeneration in forest gaps compared with the understory for the dominant species in pine-oak mixed forest. Here, we tested whether rodent seed predation or dispersal was beneficial for gap regeneration. We tracked the seed predation and dispersal of Quercus aliena var. acuteserrata and Pinus armandii using coded plastic tags in the forest understory close to gaps. Our results demonstrated that the proportions of initial buried seeds of both species were significantly more abundant in the forest understory compared with gaps. After seed caching, however, significantly lower proportions of the seeds of both species survived in the forest understory compared with gaps during the 30-day observation period. The final survival proportions of the seeds cached in the forest understory were lower than those cached in the gaps the next spring, which indicated that small rodents rarely retrieved scatter-hoarded seeds from forest gaps. Our findings suggest that rodent seed predation patterns contribute to the regeneration of the dominant species in gaps compared with the understory in a pine-oak mixed forest. In the study area, reforestation usually involves planting seedlings but direct sowing in forest gaps may be an alternative means of accelerating forest recovery and successional processes.
The study aimed to describe the seed pool accumulated in the nest material of Magpie Pica pica, and to determine the importance of this mechanism of seed dispersal for such ecological processes as colonization of new habitats and expansion of alien plants. The seedling germination and seed extraction methods were used to determine seed abundance in the soil layer, the inner layer, and in the lining of 9 nests collected in three types of agricultural landscape: the first with domination of arable fields; the second with similar shares of arable fields and other landscape elements such as meadows of different types, shrubs, tree clumps and rushes; and the third with domination of lowland hay meadows. In all the nests, considerable numbers of diaspores were found (from 26 to 371 seeds per nest, belonging to more than 80 taxa). The main plant groups found in the nests are species connected with field roads, weeds and ruderal species, but also meadow and brushwood species were found there. The soil was gathered by birds from habitats with low vegetation cover and large areas of bare soil. Although the structure of seed pool of nests suggests that soil was mainly collected in the close vicinity of the nests’ future location, this mechanism of seed dispersal can probably be involved in long distance dispersal. Seeds of two rare kenophytes: Erucastrum gallicum (Willd.) O. E. Schulz and Diplotaxis tenuifolia (L.) DC were found in the material of nests localized more than 100 m away from their closest populations. It can be assumed that this mechanism of seed dispersal can play a potential role in the expansion of alien plants and colonisation of new habitats.
All yew plants in the Kórnik Arboretum have been plotted onto maps of individual sectors and analysed with respect to location category (“near trunk”, “under canopy”, “in the open”), size (assumed to reflect age), genus of tree associated with in the “near trunk” category and environmental factors characterising the respective Arboretum sectors. There is practically no regeneration “in the open” (0.2%), most of it 82.5% is “under canopy” and only 17.3% “near the trunk”. It is assumed that thrushes (Turdidae) are primarily responsible for regeneration in the under canopy category (endozoochoria) and nuthatches (Sitta europea L.) in the near trunk category (synzoochoria). Under canopy regeneration exists in all size classes while near the trunk there is a distinct decline in the number of yew plants with increase in size (age) suggesting that conditions for further development there are less favourable. Nutchatches disperse yew seeds in the vicinity of mother plants, for cleaning them preferring trees to shrubs and particularly trees with smooth bark trunks (Fagus, Carpinus), however yew survival near the trunk is better under conifers. Thrushes disperse yew seed over wider areas. Survival of yews is best under loose canopies, in moderate shade, on drier well draining, low pH, soils.
It was proposed previously that passive dispersal by migratory aquatic birds explain the widespread distribution of many wetland organisms. Several experimental studies have shown that many widespread wetland plant species can be readily dispersed within the guts of Anatidae. However, it is unclear whether plants with a more restricted distribution are able to disperse via waterbirds. This paper addresses the dispersal ability and germination ecology of the little-known Hungarian milkvetch Astragalus contortuplicatus, which occurs on banks of continental rivers and has a limited and unpredictable distribution. To test whether limited capacity for endozoochory by waterfowl could explain the sporadic appearance of this species, we force-fed ten captive mallards (Anas platyrhynchos) with 100 milkvetch seeds each. Droppings were collected for up to 45 h after feeding. Intact and viable seeds were found in the droppings of each mallard, and altogether 24.7% of seeds fed were recovered intact. The proportion of retrieved seeds that germinated (27.0%) was significantly higher than that of untreated control seeds (0.5%), but significantly lower than that of mechanically scarified seeds (96.0%). Retrieved seeds that germinated developed into healthy mature plants. Given the average flight velocity of mallards, seeds of A. contortuplicatus may travel up to 1600 km inside the digestive tract of migrating individuals. Our results suggest that avian vectors may be more important for the dispersal of rare higher plants (especially those with a hard seed-coat) than hitherto considered. Moreover, they suggest that rarity does not necessarily indicate limited dispersal ability, and may instead be explained by specific habitat requirements.
The foraging behavior of greater short-nosed fruit bats (Cynopterus sphinx) on wild banana (Musa acuminata) and subsequent dispersal of seeds were studied in the Tropical Rainforest Conservation Area, Xishuangbanna Tropical Botanical Garden, Yunnan province, by direct observation of marked fruits, mist netting, and seed collection. The mean number (± SE) of individual C. sphinx captured by mist net were 2.2 ± 0.33/day and 1.4 ± 0.32/day in the rainy season (September to October) and dry season (November to December), respectively; the difference was not significant. The number of seed pellets expelled was 9.0 ± 1.12/day and 7.2 ± 1.37/day in the rainy and dry seasons respectively; again the difference was not significant. The removal curves for marked fruit were similar for 10 focal trees. Fruits were consumed heavily within two weeks after ripening and all the marked fruit were removed within one month. The difference in seed dispersal was significant between different feeding roosts indicating that patterns of seed dispersal may not be uniform. We found the seeds of M. acuminata can be dispersed by C. sphinx to a distance of about 200 m, and C. sphinx can be considered as an effective seed disperser of M. acuminata.
The droppings of the Grey Partridge Perdix perdix L. wintering on a set-aside field were found to contain 99.3% of Amaranthus retroflexus and 0.7% of Chenopodium album seed coat fragments. A bird consumed on average 3008 (± 95% CL = 2699–3317) weed seeds per 1 g of droppings. The excreted seed coat remnants made up c. 21% of the swallowed seed mass. Approximately 0.3% of the ingested seeds passed undamaged through the gut. The number of undamaged seeds in the droppings was not significantly correlated with the weight of droppings and the amount of the excreted sand grains, seed coat fragments and other plant parts. After over 1.5 years of storage, 3 out of 18 sown undamaged seeds of A. retroflexus germinated. The average germination time of the excreted seeds was 10 days, while for the fresh ones it amounted to 8.5 days. Our results shows that the Gray Partridge is poor seed disperser and it play important role as predator of A. retroflexus seeds.
The study aimed to evaluate the role of the Rook Corvus frugilegus in the long-distance seed dispersal in agricultural landscape. According to the literature, Rooks feed in the distance 0.3–1 km from the breeding colonies and 10–40 km from winter communal roosts, and these can be also the potential seed dispersal distances. We concentrated on the dispersal of diaspores of ornitochorous species and weeds (called non-ornitochorous) taken probably incidentally during foraging for other edible plant material. The contents of 528 pellets was analysed, 304 were collected at six sites of breeding colonies located in five rural parks and in one park on the city outskirts, and 224 under three winter roosts in the cities. Seeds representing 45 taxa were found, the most important groups among them are: ornitochorous species (10 taxa), non-ornitochorous (27 taxa, mainly weeds and ruderal species) and cereals (4 species). The mean number of seeds varied between 221 and 442 seeds per 100 pellets in the case of breeding colonies, and between 102 and 347 for wintering roosts. Fruits of ornitochorous species are an important element of the diet of the Rook: Cerasus avium and Fragaria sp. during breeding season and Vitis sp., Sorbus aucuparia and Sambucus nigra during winter. Nonornitochorous species are present in pellets in lower numbers and frequencies than ornitochorous ones and they can be divided into two groups: those transported during breeding season (mainly Stellaria media) and those during winter (Setaria sp. and Echinochloa crus-galli). We estimated that the number of non-ornitochorous seeds transported by birds from the biggest observed winter roosts can exceed 400 thousands seeds per month. The value is much lower in the case of the biggest breeding colony: approximately 16 thousands of propagules. We also checked if species found in pellets can germinate in natural conditions under the studied colonies. Viable individuals of 15 nonornitochorous and of one ornitochorous species were found there, and it was observed that disturbances of soil surface promote germination of some analysed species.
The study examine s the vegetation diversity (235 herbaceous species) in variable road-site types in terms of life history components (life traits) like life form, type of pollination, seed dispersal, spreading ability, life strategy according to Grime’s classification, and in terms of habitat preferences using Ellenberg’s indicator value (in relation to light, temperature, moisture, nitrogen, soil pH and soil salinity). Plants registered as alien species were evaluated also according to invasive status, level of abundance, introduction mode and land use habitat. Study localities (9 sites) were situated in the Českomoravská highlands and the South Bohemian regions (Czech Republic). The plant species were recorded in the bands (width in range of 1.5–3.0 m) along the verge of two types of roads (motorways with median stripes) and secondary roads (II and III classes). In total – road length of about 15 km and the total area of roadside vegetation of about 8 ha were surveyed. The annual/therophyte species with a tendency to seed dispersed by wind, preferring a light and dry habitat, and having the RC (competitive-ruderal) life strategy were mainly found along the motorways. It means that road verges along motorways are quite insolated and constitute the dry habitats, probably suitable for ruderal, weedy, non-native, and invasive species. On the contrary, species with a tendency to vegetative reproduction and the C (competitive) strategy occur mainly along the secondary roads. It seems that the secondary roads are alternative habitats for grassland flora. Species occurred on the verges of the secondary roads do not belong to the particular group of the life traits. The salt tolerant species Puccinellia distans (Jacq.) Parl. was found along all types of roads. Almost 24% of all recorded herbaceous species growing in road-sites were alien species.
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