Effects of wind speed,underlying surface,and seed morphological traits on the secondary seed dispersal in the Tengger Desert,China

The maintenance of sand-fixing vegetation is important for the stability of artificial sand-fixing systems in which seed dispersal plays a key role.Based on field wind tunnel experiments using 11 common plant species on the southeastern edge of the Tengger Desert,China,we studied the secondary seed dispersal in the fixed and semi-fixed sand dunes as well as in the mobile dunes in order to understand the limitations of vegetation regeneration and the maintenance of its stability.Our results indicated that there were significant variations among the selected 11 plant species in the threshold of wind speed(TWS).The TWS of Caragana korshinskii was the highest among the 11 plant species,whereas that of Echinops gmelinii was the lowest.Seed morphological traits and underlying surface could generally explain the TWS.During the secondary seed dispersal processes,the proportions of seeds that did not disperse(no dispersal)and only dispersed over short distance(short-distance dispersal within the wind tunnel test section)were significantly higher than those of seeds that were buried(including lost seeds)and dispersed over long distance(long-distance dispersal beyond the wind tunnel test section).Compared with other habitats,the mobile dunes were the most difficult places for secondary seed dispersal.Buried seeds were the easiest to be found in the semi-fixed sand dunes,whereas fixed sand dunes were the best sites for seeds that dispersed over long distance.The results of linear mixed models showed that after controlling the dispersal distance,smaller and rounder seeds dispersed farther.Shape index and wind speed were the two significant influencing factors on the burial of seeds.The explanatory power of wind speed,underlying surface,and seed morphological traits on the seeds that did not disperse and dispersed over short distance was far greater than that on the seeds that were buried and dispersed over long distance,implying that the processes and mechanisms of burial and long-distance dispersal are more complex.In summary,most seeds in the study area either did not move,were buried,or dispersed over short distance,promoting local vegetation regeneration.

Modeling Analysis of Factors Influencing Wind-Borne Seed Dispersal: A Case Study on Dandelion

A weed is a plant that thrives in areas of human disturbance, such as gardens, fields, pastures, waysides, and waste places where it is not intentionally cultivated. Dispersal affects community dynamics and vegetation response to global change. The process of seed disposal is influenced by wind, which plays a crucial role in determining the distance and probability of seed dispersal. Existing models of seed dispersal consider wind direction but fail to incorporate wind intensity. In this paper, a novel seed disposal model was proposed in this paper, incorporating wind intensity based on relevant references. According to various climatic conditions, including temperate, arid, and tropical regions, three specific regions were selected to establish a wind dispersal model that accurately reflects the density function distribution of dispersal distance. Additionally, dandelions growth is influenced by a multitude of factors, encompassing temperature, humidity, climate, and various environmental variables that necessitate meticulous consideration. Based on Factor Analysis model, which completely considers temperature, precipitation, solar radiation, wind, and land carrying capacity, a conclusion is presented, indicating that the growth of seeds is primarily influenced by plant attributes and climate conditions, with the former exerting a relatively stronger impact. Subsequently, the remaining two plants were chosen based on seed weight, yielding consistent conclusion.

Seed Dispersal of Citharexylum tetramerum and Ziziphus penduculata by Carnivorous in a Xerophilous Scrub at Tehuacan, Puebla, Mexico

Seed dispersion reduces the depredation rate and increases genetic flow. Some species of Carnivora consume fruits as a standard component of their diet, so they become potential seed dispersers. In Mexico, a few studies evaluated carnivorous as seed dispersers, especially in dry ecosystems. Citharexylum tetramerum and Ziziphus pedunculata are endemic plants from the Tehuacán-Cuicatlán’s Biosphere Reserve (TCBR);however, there are very little data about dispersal seeds for both species. We assessed the germination of seeds ingested by carnivores obtained from feces. We compared them with seeds from fruits as a control group. At the Metropolitan University laboratory, we germinated seeds, from: plants, scats, and fruits, and we used Kruskall Wallis Test to compare percentage and germination rate. C. tetramerum seeds ingested by a carnivorous decreased in germination percentage and rate. In contrast, the percentage and rate of germination of Z. pedunculata seeds from carnivorous feces were higher than the control group. However, Z. pedunculata control seeds did not germinate during tests, but at the end of the tests, we found that 90% of control seeds were not dead, so they were dormant seeds. Carnivores interact as legitime dispersers for both plants because they are keeping the viability of seeds. Still, we only showed that Z. pedunculata gut carnivores broke with the dormancy of seeds. We consider that in future research, it could be essential to identify other animals that consume fruits of those plants and if it is possible to follow seeds after they have been removed. Those points could help to get better understanding of those endemic plants from Tehuacán.

Bulbuls and crows provide complementary seed dispersal for China's endangered trees

Background: Different functional frugivores generally exhibit unequal contributions,both in terms of quantity(seed removal) and quality(seedling recruitment),to effective seed dispersal of plant species.However,variations in this dispersal pattern generated by frugivores across different regions are still unknown.Methods: In our study,we evaluated the contributions of two functional frugivore bird groups,the bulbuls(Pycnon?otidae) and crows(Corvidae),in both the seed removal and seedling recruitment of the endangered Chinese yew tree(Taxus chinensis) across three different geographical regions in eastern China.Results: The dominant crow species,Urocissa erythrorhyncha,was the most common disperser crow species at all sites,while the dominant bulbul species varied across the three sites.Furthermore,the two functional groups of dispersers diverged in the aspects of seed removal(quantity) and seedling recruitment pattern(quality).While bulbuls outperformed crows in seed removal(quantity),crows took more seeds to a safer site for seedlings(quality).Conclusions: Our results highlight the importance of variations in the effective seed dispersal patterns of different functional disperser groups across different regions in the conservation and management of endangered tree species.

Pollination and seed dispersal of Aquilaria sinensis(Lour.)Gilg(Thymelaeaceae):An economic plant species with extremely small populations in China

Pollination and seed dispersal in angiosperms have long been investigated in order to understand the coevolution of plants and animals.However,the signals from flowers and/or seeds to attract pollinators and/or seed dispersers have received comparatively little attention.In this study,the pollination biology and seed dispersal of the vulnerable agarwood plant Aquilaria sinensis(Lour.) Gilg,a traditional medicinal plant in China,was studied in its natural distribution range.The reproductive tactics of A.sinensis were studied in detail by employing various tests dealing with fruit set and also seed dispersal.Dynamic headspace extraction followed by GC-MS analysis was also performed in order to reveal the composition of floral scent.The results showed that noctuids and pyralids are the most effective pollinators of pollinator-dependent A.sinensis.The main compounds of the floral scent were(E,E)-α-Farnesene(61.9 ± 3.2%),trans-Ocimene(16.6 ± 1.2%),and Benzyl salicylate(4.6 ± 1.1%).The results obtained from seed dispersal experiments indicate that hornets are effective seed dispersers and they may play an important role in long-distance seed dispersal of A.sinensis.Based on our findings,we recommend several protection methods for this threatened agarwood plant in China.

Bird functional traits affect seed dispersal patterns of China's endangered trees across different disturbed habitats

Background: The most dominant global threat to natural forests and their biodiversity is land-cover change, which has negative impacts on both species persistence and ecosystem functions. Land-cover change could alter animal behaviour and disrupt seed dispersal mutualisms. However, its effects on the role of bird functional traits in seed dispersal are not well studied.Methods: In the present study, we assessed the contributions of bird functional traits(behavioural traits: food habit, foraging pattern, foraging frequency, and habitat specialisation; morphological traits: weight, body length, wing length, and tail length) to both seed removal patterns and seed dispersal distances of an endangered and native tree species, Chinese yew(Taxus chinensis), in farmland, patchy habitat, and natural habitat, of southeast China.Results: We found that the ability of T. chinensis trees to form seed dispersal mutualisms with local birds varied across the different disturbed habitats. As a consequence of these mutualisms, more seeds were removed by birds from the patchy habitat than from the other two habitats. The number of seeds removed increased with bird foraging frequency. Moreover, the dispersal distance from the three habitats differed, and the longest dispersal distances were observed at both the patchy habitat and the farmland site. Seed dispersal distance increased with bird tail and wing length.Conclusions: Our results highlight the importance of bird functional traits in the seed dispersal patterns of endangered trees across disturbed forest habitats, which should be considered for tree conservation and management.

Seed traits and taxonomic relationships determine the occurrence of mutualisms versus seed predation in a tropical forest rodent and seed dispersal system

Although many studies have been carried out on plant-animal mutualistic assemblages,the roles of function­al traits and taxonomy in determining both whether interactions involve mutualisms or predation and the struc­ture of such assemblages are unclear.We used semi-natural enclosures to quantitatively assess the interaction strengths between seeds of 8 sympatric tree species and 4 rodent species in a tropical forest in Xishuangban­na,Yunnan,Southwest China.We found 2 clusters of species in the seed-rodent network represented by 2 gen­era in the Fagaceae(Castanopsis,Lithocarpus).Compared to seeds of 3 Castanopsis species,seeds with heavy weight,hard coat or caloric content(including 3 Lithocarpus species)were eaten less and more frequently hoarded by rodents.In turn,hoarded seeds showed less predation and more mutualism with rodents.Our results suggest that seed traits significantly affected the hoarding behavior of rodents,and,consequently,the occurrence of mutualisms and predation as well as assemblage structure in the plant-animal seed dispersal system.Taxo­nomically-related species with similar seed traits as functional groups belong to the same substructures in the assemblage.Our results indicate that both seed traits and taxonomic relationships may simplify thinking about seed dispersal systems by helping to elucidate whether interactions are likely to be dominated by predation or mutualism.

Scatterhoarding rodents favor higher predation risks for cache sites:The potential for predators to influence the seed dispersal process

Scatterhoarding rodents often place caches in the open where pilferage rates are reduced,suggesting that they tradeoff higher risks of predation for more secure cache sites.We tested this hypothesis in two study systems by measuring predation risks inferred from measures of giving-up densities(GUDs)at known cache sites and other sites for comparison.Rodent GUDs were measured with small trays containing 3 L of fine sand mixed with sunflower seeds.In the first experiment,we relied on a 2-year seed dispersal study in a natural forest to identify caches of eastern gray squirrels(Sciurus carolinensis)and then measured GUDs at:(i)these caches;(ii)comparable points along logs and rocks where rodent activity was assumed highest;and(iii)a set of random points.We found that GUDs and,presumably,predation risks,were higher at both cache and random points than those with cover.At the second site,we measured GUDs of eastern gray squirrels in an open park system and found that GUDs were consistently lowest at the base of the tree compared to more open sites,where previous studies show caching by squirrels to be highest and pilferage rates by naïve competitors to be lowest.These results confirm that predation risks can influence scatterhoarding decisions but that they are also highly context dependent,and that the landscape of fear,now so well documented in the literature,could potentially shape the temporal and spatial patterns of seedling establishment and forest regeneration in systems where scatterhoarding is common.

Importance of bird traits for seed dispersal patterns of co-fruiting trees in a patchy forest

Habitat fragmentation is globally one of the most important drivers of change in biodiversity.Seed dispersal by birds is crucial for tree regeneration in remnant patchy forests,yet how bird traits affect seed dispersal pattern is still poorly understood.We studied the extent to which bird traits affect seed-removal networks and whether these traits affect seed deposition and seedling recruitment for 3 co-fruiting tree species(Taxus chinensis,Cin­namomum bodinieri and Machilus thunbergii)in a patchy forest.A total of 17,18 and 10 bird species were re­corded foraging for seeds of T.chinensis,M.thunbergii and C.bodinieri,respectively.Frequency of bird visi­tation increased with tail length,wing length and body length.Furthermore,bird body length,bill length,body weight and wing length were important in the strength of the seed removal network.During foraging,6 bird species exhibited different patterns of microhabitat utilization and their perching frequency increased with bird weight and tarsus length.As a consequence,frequency of habitat use,bird length and tarsus length were im­portant in determining the number of deposited seeds.For seedling recruitment,seedling number increased with bird tarsus length and weight,but decreased with wing length.Overall,our results showed that various bird traits not only affected seed removal,but also influenced the subsequent processes of seed deposition and seed­ling distribution in a patchy forest.These results thus highlight the importance of large-bodied birds for plant recruitment and point out the need to prioritize the protection and conservation of these birds in remnant patchy forests.

Spatial and temporal effects on seed dispersal and seed predation of Musa acuminata in southern Yunnan, China

Wild bananas are abundant in tropical areas and many ecologists have observed that the succession process is quicker following increased disturbance.This study was conducted to analyze animal–seed interactions and their effects on the seed fate of a wild banana species(Musa acuminata)in tropical southern Yunnan(China)through experiments considering spatial(site and habitat)and temporal(seasons)variation.The largest proportion of fruits(81%)was removed by frugivorous seed dispersers,especially by bats at nighttime.Only 13%of the fruits were removed by climbing seed predators(different species of rats).In the exclosure treatment,rodents accounted for a significantly higher total artificially exposed seed removal number than ants,but with spatial and temporal differences.The highest seed predation rate by rodents(70%)was found in forest with wild banana stands,corresponding with the highest rodent diversity(species numbers and abundance)among the habitat types.In contrast,the seed removal number by ants(57%)was highest in the open land habitats,but there was no close correlation with ant diversity.Seed removal numbers by ants were significantly higher in the dry compared to the rainy season,but rodent activity showed no differences between seasons.The overall results suggest that the largest proportion of seeds produced by wild banana are primarily dispersed by bats.Primary seed dispersal by bats at nighttime is essential for wild banana seeds to escape seed predation.

Seed dispersal by hornets:An unusual insect-plant mutualism

Vespicochory, seed dispersal by hornets, is a rare seed dispersal mechanism in angiosperms and, to date, there are few records of this phenomenon.Through field investigations and behavioral assays conducted in four populations of Stemona tuberosa from 2011–2016, we demonstrate that hornets are the primary seed dispersers of S. tuberosa and play an important role in "long-distance" seed dispersal in this species. Furthermore, some ant species act as secondary dispersers and may transport the seeds to safe sites.Hornets and ants provide complementary seed dispersal at different spatial scales. This unique example of insect-plant mutualism may be an underestimated but important strategy to ensure "long-distance" seed dispersal in other myrmecochorous plants.

Endozoochorous seed dispersal by golden snub-nosed monkeys in a temperate forest

Seed dispersal is essential for plant recruitment and the maintenance of biodiversity.Colobine monkeys are primarily folivorous,but they also consume fruits and are often assumed to be seed predators.Although they are known to be epizoochorous seed dispersers,their role as endozoochorous seed dispersers needs reassessment.We examined potential endozoochory in golden snub-nosed monkeys(Rhinopithecus roxellana)at Dalongtan in Shennongjia National Park,central China,by assessing potential germination of ingested seeds(n=1806,9 species)from fecal samples.Intact seeds were in almost all fecal samples(ranging from 5-130 seeds),and ingested seeds were from small seeded species(seed width<4.5 mm).The 2 most abundant species were Actinidia arguta(73%)and Rosa caudata(15%).The fruits of A.arguta were unripe when ingested(i.e.effective seed predation)and the ingested seeds did not germinate in the trials.Therefore,ingestion of unripe seeds does not lead to effective seed dispersal.However,germination rates of defecated R.caudata(9%)were greater than control seeds(6%and 0%),demon-strating potential endozoochorous seed dispersal.Thus,colobine monkeys do indeed disperse mainly small-seeded from multi-seeded fruits through potential endozoochory and this process enhances the recruitment of seedlings.

A GPU-based multi-resolution algorithm for simulation of seed dispersal

In forest dynamics models, the intensive computation and load involved in the simulation of seed dispersal can become unbearably huge for large-scale forest analysis. To solve this problem, we propose a multi-resolution algorithm to compute seed dispersal on GPU. By exploiting the computation parallelism of seed dispersal, the computation of the whole forest plot is divided into multiple small plot cells, which are computed independently by parallel threads on GPU. To further improve the calculation efficiency with limited threads scale for GPU computation, we propose a hierarchical method to cluster the plot cells into a multi-resolution form according to the biological curves of tree seed dispersal. Experimental results show that our algorithm not only greatly reduces computational time but also obtains comparably correct results as compared to the naive GPU algorithm, which makes it especially suitable for large-scale forest modeling.

Seed dispersal and seedling recruitment of trees at different successional stages in a temperate forest in northeastern China

spatial distribution of adult trees in a forest community is determined by patterns of both seed dispersal and seedling recruitment.the objectives of our study were to understand the processes of seed dispersal and seedling recruitment of dominant tree species in a temperate forest of northeastern China and to identify the factors constraining seed dispersal and seedling establishment at different stages of forest succession.Methods During three summer and autumn sessions between 2006 and 2008,altogether 113080 seeds from 22 different tree species were collected in three large field plots representing different for-est types in the Changbai mountain region of northeastern China.the spatial distribution of seed abundance was analyzed using a syrjala test.regeneration success of nine major tree species was assessed using variables defining‘limitations’in‘seeds’and‘seed-ling establishment’.Important Findings We found that seed production fluctuated between years and varied greatly with forest types.Four tree species,Acer spp.,Fraxinus man-dshurica,Tilia amurensis and Betula spp.,had the greatest seed pro-duction and the widest range of seed dispersal,whereas Quercus mongolica showed the most sustained seed production pattern.the spatial patterns of seed abundance differed significantly among forest types and years.the tree species investigated in this study differed in the degree of seed limitation,as well as in limitation of seedling establishment.there were both negative and positive correlations between seed density and seedling density,depending on site and parental tree density.seeds of 16 tree species were found in the Populus davidiana-Betula platyphylla forest(PbF)plot,11 in the conifer and broad-leaved mixed forest(CbF)plot but only 8 in the broad-leaved-Korean pine mixed forest(bKF)plot.the number of seed-contributing species was not only greater in the secondary forests(CbF and PbF plots)than in the primary forest(bKF plot)but was also more variable during the 3 years of assessment.results from the correlations between seed density and seedling occurrence and that between parental tree density or seed weight and dispersal limitation confirm our intuitive expectations,i.e.heavy seeds had greater dispersal limitation but higher establishment success than light seeds.

Seed dispersal in Hong Kong,China:past,present and possible futures

In the present article,published and unpublished information regarding seed dispersal in the degraded landscape of Hong Kong,China,is reviewed.Information was available for 1681 native plant species,of which 1165 were assigned to probable seed dispersal modes.Endozoochory accounted for one-third(34.4%)of all species evaluated,half(54.4%)of those from forests,and more than two-thirds(69.2%)of all trees and tall shrubs.Wind dispersal(25.9%)and dispersal by an unknown agent(30.7%)accounted for most of the rest,with the unknown species mostly small-seeded herbs.Although the frugivore fauna of the Hong Kong region has been truncated since the late Pleistocene,there are few clear examples of failed mutualisms.The most striking is the absence of scatter-hoarding rodents from Hong Kong,despite the presence of forest trees that appear to require them for effective dispersal.There are also some large Lauraceae fruits that appear to be targeted at larger-gaped birds than currently present.Most endozoochorous species are dispersed by 3 small passerine birds(Pycnonotus jocosus,P.sinensis,and Zosterops japonicus),with larger birds,fruit bats(Cynopterus sphinx,Rousettus leschenaulti),rhesus macaques(Macaca mulatta),civets(Paguma larvata,Viverricula indica),and muntjacs(Muntiacus muntjac)accounting for the remainder.The low plant diversity in frugivore droppings,seed traps,and secondary vegetation suggests plant succession may be dispersal limited,although this has not been investigated experimentally.Planting underdispersed species is the simplest solution but,in the longer term,the(re)introduction of a scatter-hoarding rodent should be considered as well as that of other locally and regionally extinct frugivores.

Dispersal and germination of winged seeds of Brandisia hancei,a shrub in karst regions of China

Brandisia hancei(Paulowniaceae)is a widely distributed shrub in karst regions in southwestern China.Its seeds have a membranous wing,and they mature just before the rainy season begins.To assess the effect of the wing on seed dispersal and germination of B.hancei,we measured the dispersal distance at varying wind speeds and release heights,falling duration from different release heights,floating duration on still water,rates of imbibition of water,and drying and soil adherence to seeds.Germination experiments were conducted on intact and de-winged seeds immediately after harvest.The wing increased the falling duration in still air and the floating ability on water.Dispersal distance of winged and de-winged seeds did not differ at a wind speed of 2.8 m s1,but at 3.6 and 4.0 m s1 dispersal distances were greater for de-winged than for winged seeds.Seed wing had little effect of absorption and retention of water,but significantly increased soil adherence to the seeds.Mature seeds were non-dormant and germinated to over 90%with a mean germination time of about 10 days.By combining the environmental conditions in karst habitat with the seed traits of B.hancei,we conclude that dispersal and germination of winged seeds are adapted to the precipitation seasonality in heterogeneous habitats absence of soil.

Habitat differences in dung beetle assemblages in an African savanna–forest ecotone:implications for secondary seed dispersal

The probability and pattern of secondary seed dispersal by dung beetles(Scarabaeinae)depend on their community structure and composition at the site of primary deposition,which,in turn,seem to be strongly determined by vegetation.Consequently,we expected pronounced differences in secondary seed dispersal between forest and savanna in the northern Ivory Coast,West Africa.We found 99 dung beetle species at experimentally exposed dung piles of the olive baboon(Papio anubis(Lesson,1827)),an important primary seed disperser in West Africa.Seventy-six species belonged to the roller and tunneler guilds,which are relevant for secondary seed dispersal.Most species showed a clear habitat preference.Contrary to the Neotropics,species number and abundance were much higher in the savanna than in the forest.Rollers and tunnelers each accounted for approximately 50%of the individuals in the savanna,but in the forest rollers made up only 4%.Seeds deposited into the savanna by an omnivorous primary disperser generally have a higher overall probability of being more rapidly dispersed secondarily by dung beetles than seeds in the forest.Also,rollers disperse seeds over larger distances.In contrast to other studies,small rollers were active in dispersal of large seeds,which were seemingly mistaken for dung balls.Our results suggest that rollers can remove seeds from any plant dispersed in primate dung in this ecosystem.

Roles of species-preferential seed dispersal by ants and endozoochory in Melampyrum(Orobanchaceae)

Aims Melampyrum pratense and M.subalpinum are two myrmeco-chorous species,which possess similar habitat requirements and frequently occur together.Despite this,their population sizes differ markedly.Melampyrum pratense populations are usually very large,whereas M.subalpinum has rather small and isolated populations.We suggest that such an imbalance might be partially influenced by the difference in ant-mediated seed-removal rates.genus Melampyrum is considered to be exclusively myrme-cochorous,though to achieve the recent distribution of some Melampyrum species during the Holocene myrmecochory would be highly insufficient.We suggest that endozoochory takes place in the long-distance migration,whereas myrmecochory is important for the removal of seeds on a local scale.Methods For seed-preference analysis,M.pratense and M.subalpinum mixed seed samples were placed around Formica polyctena anthills.after a period of time,the remaining seeds of both species were counted for each sample.The results were analysed by analysis of variance and generalized linear mixed-effect model.To test myrmecochorous removal distances,M.pratense seeds were covered with fluorescent dactyloscopic powder and placed in the vicinity of a large ant trail.The area around the starting plot was searched in the dark using uV lED torchlight 7 h after the beginning.The distance from the starting plot was measured for each seed found.birds,rodents,leporine and a ruminant were fed with M.pratense seeds and fresh plants to test the possibility of endozoochorous dispersal of the species.animal droppings were searched for intact seeds.Important Findingsour field studies show that from mixed seed samples,containing both species,ants significantly preferred the seeds of M.pratense.This may be one of factors that has positive influence on M.prat-ense success in seed dispersal on mixed stands and consequently in the colonization of favourable sites.Experiments focusing on ant-mediated dispersal distance revealed that F.polyctena ants are able to move seeds over a distance of 36 m in only 7 h.This distance is among the furthest known myrmecochorous removals of forest plant seeds.a new Melampyrum seed disperser Oligolophus tridens(opiliones)was observed repeatedly.our pilot study documented that Melampyrum seeds are able to pass through the digestive tract of a cow intact.This suggests that large ruminants such as deer,bison or forest-grazing livestock may function as important long-distance dispersers of Melampyrum species.

Effectiveness of seed dispersal by ants in a Neotropical tree

Seed dispersal and subsequent recruitment is the template on which forest regeneration takes place.Hence,considering the scale over which ecological processes occur is key for understanding the overall impact of various dispersal agents.To explore leafcutter ant(Atta colombica)dispersal effectiveness in space and time,seed movement and subsequent recruitment of a large-seeded predominately vertebrate-dispersed tree,Simarouba amara(Aubl.Simaroubaceae),was investigated on Barro Colorado Island,Panama.At each of 218 reproductive-sized adults(>20 cm diameter at breast height),presence or absence of a leafcutter ant colony was noted,with extensive checks for Atta activity taking place at or in close proximity to seed and seedling transects,which extended 4 cardinal directions for 30 m from each reproductive female tree(n=74).Only at 2 S.amara trees were nests observed,and in these areas a dense S.amara seedling carpet was observed.Although nearby nest and dump sites might increase local S.amara recruitment in the short term,mortality at these sites is complete or nearly so.Hence,the seed dispersal effectiveness by leafcutter ants appears to be ephemeral and likely contributes inconsequentially to the long-term recruitment and distribution patterns of the species.This finding highlights the importance of evaluating disperser effectiveness at ecologically relevant spatiotemporal scales.

Fruits foraging patterns and seed dispersal effect of frugivorous birds on Hippophae rhamnoides sinensis

Behaviors of 18 species of birds eating fruits of Hippophae rhamnoides spp.sinensis were observed from September 2003 to March 2004.Their foraging patterns were found to be very different and can be divided into five classes:(1)direct swallowing the fruits on crown of the shrubs and sometimes regurgitating seeds soon after;(2)carrying the fruits to their perching sites and swallowing;(3)pecking the fruits from the shrubs to the ground,eating pulp and seeds but leaving pericarp;(4)pecking through the pericarp,eating pulp and leaving pericarp and seeds;(5)pecking through the pericarp on the top of fruits,and only eating seeds.These foraging patterns have different effects on seed dispersal of H.rhamnoides spp.sinensis.The germina-tion experiment of three groups of seeds(seeds from feces,dry fruits and extracted seeds from dry fruits)was carried out.Although ingestion processes of birds had some adverse effects on the seed germination of H.rhamnoides spp.sinensis,the seeds from feces still have a relatively higher germination ratio.H.rhamnoides spp.sinensis provides food to a variety of frugivorous birds,and the birds disperse its seeds.Thus,a mutually beneficial relationship between the bird and the seed is formed.