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.

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.

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.

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.

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.

Using endocarp-remains of seeds of wild apricot Prunus armeniaca to identify rodent seed predators

Some rodent-dispersed seeds have a hard seed-coat(e.g.woody endocarp).Specific scrapes or dental marks on the hard seed-coat left by rodents when they eat these seeds can be used to identify seed predators.In this study we measured the morphological traits of endocarp-remains of seeds of wild apricot Prunus armeniaca used by Chinese white-bellied rats Niviventor confucianus and Korean field mice Apodemus peninsulae.We established their Fisher's linear discriminant functions to separate endocarp-remains between the two predators.A total of 90.0% of the endocarp-remains left by Korean field mice and 88.0% of those left by Chinese white-bellied rats were correctly classified.The overall percentage of correct classification was 89.0%.One hundred and sixty endocarp-remains of unknown what species predated them were classified using the functions.The method may allow more reliable quantitative studies of the effects of Chinese white-bellied rats and Korean field mice on seed consumption and dispersal of wild apricot and this study might be used for reference in other studies of seed predators identification on hard seeds.

Rodent-mediated plant community competition:what happens to the seeds after entering the adjacent stands?

Background:Seed dispersal by scatter-hoarding animals can affect the developmental dynamics of plant communities.However,how animals might participate in plant inter-community competition has rarely been investigated.Forest community junction is an area where the competition between plant communities is most prominent and animal activity is more frequent.At present,little is known about how scatter-hoarding animals might assist competitions by adjacent plant communities.Thus,for 3 years(2015–2017),we tracked the fate of 2880 tagged seeds(Quercus aliena var.acuteserrata,Pinus tabuliformis,and P.armandii seed)placed near an edge where the forest composition changes from a pine forest to an oak forest in northwestern China.Results:We found that the seed fates differed when Quercus and Pinus seeds entered adjacent stands.In contrast to Pinus seeds,acorns that entered pine forests were characterized by higher caching rates and longer dispersal distances.Pinus seeds had the highest probability of being predated(85%)by rodents,and eleven Q.aliena var.acuteserrata seedlings were established in pine forests,although none survived in the later stages.In addition,rodents exhibited obvious selectivity in terms of the microhabitats for the seed caching sites.Conclusions:Seed fates differed when Quercus and Pinus seeds entered adjacent stands.The predation pressure by rodents on the seeds of Pinus species limited the germination of seeds and seedling establishment in oak forests.The different seed fates after their bidirectional dispersal could affect the differences in natural regeneration between pine and oak forests,and they might increase the recruitment rates for oak at the edge of an adjacent community.Rodent-mediated seed dispersal could potential unintentionally affect the competition between plant communities.

Influencing Factors of Seed Long-distance Dispersal on a Fragmented Forest Landscape on Changbai Mountains,China

Seed long-distance dispersal(LDD) events are typically rare, but are important in the population processes that determine large-scale forest changes and the persistence of species in fragmented landscapes. However, previous studies focused on species dispersed via animal-mediated LDD, and ignored those dispersed by wind. The aim of this study was to assess the effects of canopy openness, edge, seed source, and patch tree density on the LDD of seeds by wind in forest. We collected birch seeds, a typical wind-dispersed species, throughout a larch plantation. We then assessed the relationship between birch LDD and each factor that may influence LDD of seeds by wind including distance to edge, canopy openness size, distance to mature forest, and the tree density of the larch plantation. We used univariate linear regression analysis to assess the influence of those factors on birch LDD, and partial correlations to calculate the contribution of each factor to LDD. The results showed that both canopy openness and edge had significant influences on birch LDD. Specifically, a negative relationship was observed between distance to edge and birch LDD, whereas there was a positive correlation between canopy openness size and LDD. In contrast, the distance to the mature forest was not correlated with birch LDD. Our results suggest that patch tree density could potently affect the probability of LDD by wind vectors, which provides novel and revealing insights regarding the effect of fragmentation on wind dynamics. The data also provide compelling evidence for the previously undocumented effect of habitat fragmentation on wind-dispersed organisms. As such, these observations will facilitate reasonable conservation planning, which requires a detailed understanding of the mechanisms by which patch properties hamper the delivery of seeds of wind-dispersed plants to fragmented areas.

Reproductive biology of Magnolia sinica(Magnoliaecea),a threatened species with extremely small populations in Yunnan,China

Magnolia sinica is one of the most threatened trees endemic to Southeast Yunnan.Based on our investigations,only 52 individuals and eight populations are found in the wild.M.sinica has been categorized as Critically Endangered on the IUCN Red List and identified as a "Plant Species with Extremely Small Populations(PSESP)".Its fruit/seed set is very low and seedlings are rarely found in the wild.It is hypothesized that it may encounter obstacles to reproductive success.This study,therefore,focuses on its reproductive biology,knowledge of which is essential for effective conservation.Flowers of this species are protogynous and nocturnal,and possess a two-day rhythm of sexual presentation.For the first night of anthesis,the flowers are in the pistillate stage during which tepals open at dusk and close approx.1 h later(except for the open outer ones).They remain closed until the next afternoon,when flowers,now in the staminate stage,re-open and remain so until the tepals drop.Nocturnal beetles enter into the flowers and remain trapped throughout the night as the flower closes,during which time they feed on tepals.Pollen-gathering bees are found to visit the re-opened flowers and the beetles are released during this stage.Two species of Pleocomidae and Curculionidae beetles appear to be effective pollinators.M.sinica is a self-compatible,pollinator-dependent species,and its fruit/seed set can be significantly increased by hand-pollination.No functional seed dispersers have been found in its extant natural habitats.These findings suggest that it may face both pollination and seed disperser insufficiencies in its current fragmented habitats,which may account for its low regeneration.Here we propose conservation strategies based on our findings.

Regenerative Role of Soil Seed Banks of Different Successional Stages in A Saline-alkaline Grassland in Northeast China

Soil seed banks can act as a potential seed source for natural revegetation and restoration. However, in a saline-alkaline grassland, it remains unclear how the stages of vegetation succession affect the characteristics of soil seed banks and the potential of soil seed banks of different successional stages for vegetation restoration. In this study, seasonal changes of the soil seed bank, and seed production and dispersal dynamics along degradation successional gradients were investigated in a saline-alkaline grassland in Northeast China, where the dominant grass during the 1960 s, Leymus chinensis was replaced with the secondary successional order of Puccinellia chinampoensis, Chloris virgata, and Suaeda salsa, together with bare patches. It was found that the soil seed bank composition varied according to the changing vegetation and had the highest species richness(7–16) in the climax successional stage, but had a low S?rensen similarity(0.22–0.37) with the aboveground vegetation. There was a high seed density of the soil seed bank(21 062–62 166/m2 in August and December) and also high S?rensen similarity index values(0.47–0.60) in the secondary successional stages of P. chinampoensis, C. virgata, and S. salsa. In bare patches, there were many seeds in the soil seed bank and some seedlings also appeared in the aboveground vegetation, indicating the existence of a persistent soil seed bank. Seed density and species richness differed substantially among the different successional stages, which was related to the reproductive characteristics of the standing plants in vegetation communities. Due to the lack of propagules of perennial species, especially the climax species of L. chinensis, in the soil, the successful restoration of the degraded saline-alkaline grassland was not possible. The study proved that in a degraded saline-alkaline grassland dominated by biennial or annual species, the soil seed bank was important for the revegetation of the current dominant plants, but not for the restoration of the original target species. Therefore, it is necessary to induce seeds or other propagules of the target perennial species.

Effects of vegetation cover on recruitment of Ulmus pumila L. in Horqin Sandy Land, northeastern China

Understanding the effects of vegetation cover on seedling survival is helpful for promoting vegetation restoration in environmentally fragile zones. This study was conducted in the desertified, moving sand dunes of Horqin Sandy Land, Inner Mongolia, northeastern China. We hyphothesized that （1） seed density （i.e., number/m2） increases as vegetation cover increases, and （2） there will be more surviving seedlings in locations with higher vegetation covers. Total vegetation cover and initial densities of seeds, germinated seeds and surviving seedlings of Ulmus pumilia were evaluated under various vegetation covers in trying to clarify the effects of vegetation cover on the early stages of the plant life history. In agreement with the first hypothesis, initial seed densities were greater （P〈0.05） under higher vegetation covers. The relationship between vegetation cover and initial seed density was represented by a quadratic regression, where a threshold occurred with a vegetation cover of 36% （P〈0.05）. The higher total vegetation covers, however, did not result in increased densities of germinated seeds （P〉0.05）, which on average represented 16.7% of initial seed densities. Even more, three months after the study initiation, total vegetation covers were similar （P〉0.05） at all positions in the dunes, and they determined a similar number （P〉0.05） of surviving seedlings at those positions （i.e. the second hypothesis had to be rejected）. The mean number of seedlings that survived at all positions was only 4.5% of germinated seeds. The number of surviving elm seedlings （0 to 1.7 seedlings/m2） under various vegetations covers （12.2% to 20.8%） at all dune positions by late summer would most likely not contribute to vegetation restoration in the study area.

Dispersal of invasive Phytolacca americana seeds by birds in an urban garden in China

Although seed dispersal is a key process determining the regeneration and spread of invasive plant populations,few studies have explicitly addressed the link between dispersal vector behavior and seedling recruitment to gain insight into the invasion process within an urban garden context.We evaluated the role of bird vectors in the dispersal of pokeweed(Phytolacca americana),a North American herb that is invasive in urban gardens in China.Fruiting P.americana attracted both generalist and specialist bird species that fed on and dispersed its seeds.The generalist species Pycnonotus sinensis and Urocissa erythrorhyncha were the most frequent dispersers.Seedling numbers of P.americana were strongly associated with the perching behavior of frugivorous birds.If newly recruited bird species use seedling-safe perching sites,the P.americana will regenerate faster,which would enhance its invasive potential.Based on our observations,we conclude that the 2 main bird vectors,P.sinensis and U.erythrorhyncha,provide potential effective dispersal agents for P.americana.Our results highlight the role of native birds in seed dispersal of invasive plants in urban gardens.

Soil seed bank assembly following secondary succession on abandoned agricultural fields in Nicaragua

The composition and density of seeds in soils of secondary forests derived on abandoned fields after 4, 9 and 14 years of aban- donment were quantified to examine whether the soil seed bank assembles during secondary succession as the plant communities assemble. A total of 18, 37 and 48 soil samples from 4-, 9- and 14-year old sites, respectively were collected in 15 cm × 15 cm plots up to 9 cm depth. A total of 3, 5 and 9 species were found on sites abandoned 4, 9 and 14 years ago, respectively, Among different life forms, trees were highly represented in the soil seed bank of 9-year （60%） and 14-year （33%） old sites compared to 4-year old site entirely dominated by non- woody flora. The total number of seeds ranged from 327 in the 4-year old site to 146 in the 14-year old site, and the corresponding density of viable seeds ranged from 141 seeds m^-2 in the 4- year old site to 26 seeds m^-2 in the 14-year old site with a consistent decreasing pattern in the chronosequence. The similarity between the soil seed flora and the standing woody vegetation was low for both 9- and 14-year old sites while complete dissimilarity was found for 4-year old site. We concluded that the species composition of soil seed banks assemble gradually during secondary succession, but the overall seed density is still low for natural regeneration of trees to rely on. To expedite the recovery of secondary forests on such abandoned fields, the seed bank needs to be supplemented by direct seeding, enrichment planting of desired species and installing artificial perches for facilitating seed dispersal.

Maintenance of an abrupt boundary between needle-leaved and broad-leaved forests in a wetland near coast

There is an abrupt boundary between two well-developed wetland forests, a stand consisting of a broad-leaved, nitrogen-fixer Alnusjaponica and a stand of the needle-leaved Picea glehnii Masters, in eastern Hokkaido, Japan. To clarify maintenance mechanisms, we studied the forest profile, water level, groundwater and precipitation chemistry, seedling establishment patterns in relation to microhabitats, and seed migration. The profile of groundwater level insufficiently explained the abrupt boundary formation, while the groundwater chemistry differed significantly between the two forests ; i.e., EC, Na^＋, K^＋, Mg^2＋, Ca^2＋ and Cl^- were higher in P. glehnii forest and pH was lower. Precipitation in P. glehnii forest contained richer Na＋, Ca^2＋ and Cl^-, indicating that the differences in surface-water chemistry were mostly derived from precipitation. Solar radiation was less than 2.2 MJ.m^-2.d^-1 on P. glehnii forest in late June, while that was patchily distributed in A.japonica forest with a range from 1.0 to 3.7 MJ＇m^-2＇d^-1. Moss cover on the soil surface, most of which were made of Sphagnum spp., was 60% in P. glehnii forest, but was 10% in A. japonica forest. Surface water chemistry represented by pH was considered to determine the development of Sphagnum moss. About 70% of P. glehnii seedlings 〈 1.3 m in height established on moss cover. Seed-sowing experiments suggested that seed germination and seedling survival for both species were significantly higher in P. glehnii forest. Therefore, the regeneration of P. glehnii in A. japonica forest was negligible, owing to the paucity of favorable microhabitats and low seedling establishment. A. japonica regenerated only by resprouting, and the seedlings were few in both forests. In addition, A. japonica seed migration into the P. glehnii forests was greatly restricted, and low solar radiation in the P. glehnii forest contributed to low seedling survival. Based on those results, we concluded that Picea glehnii and Alnusjaponica could develop distinct and selfish environments being unsuitable for the other species and inhibit natural afforestation of another species each other by excluding invasion.

Interaction network between frugivorous birds and zoochorous plants in cloud forest riparian strips immersed in anthropic landscapes

Worldwide,tropical montane cloud forest is one of the most important and biodiverse ecosystems;however,it is also one of those most threatened by anthropic activities.These activities lead to a fragmented,deforested landscape with narrow riparian forest strips immersed in an agricultural matrix dominated by pastures.Here,we characterize the interaction network between frugivorous birds and zoochorous plants in riparian strips of cloud forest in deforested landscapes of Central Veracruz,Mexico.To characterize the network of this mutualistic interaction,we estimated network-and species-level metrics using the Bipartite R package.Nestedness,modularity and robustness were used to describe network structure.Centrality measures of degree,closeness,betweenness centrality and their relative contribution to nestedness were used to determine the importance of each bird/plant species to the network’s structure.This interaction network has 24 species of birds and 30 species of plants,with low connectance(0.11),low nestedness(11.53),and intermediate but not significant modularity(0.49).The bird species most important to network stability were Chlorospingus flavopectus,Myadestes occidentalis,and Catharus mexicanus.The most important plants were Conostegia xalapensis,C.arborea,and Rubus ulmifolius.Network robustness varied from 0.36 to 0.86 and its stability is compromised when species of birds or plants with the highest values of centrality are removed,with plant removal more detrimental.Riparian strips of cloud forest crossing deforested areas maintain a relatively rich set of birds that disperse the seeds of many forest plants,thus they are crucial to the preservation of this mutualistic network in anthropic landscapes.Network stability is severely undermined by the loss of any of the few species—whether birds or plants—with high centrality values.The most important plants for this stability are pioneer tree and shrub species that provide food for several bird species,and they are also crucial to cloud forest regeneration.A worrisome finding is that some of the bird species most important to network stability are also among the most sought-after as ornamental birds by illegal collectors in the region.

Maintenance of an abrupt boundary between needle-leaved and broad-leaved forests in a wetland near coast

There is an abrupt boundary between two well-developed wetland forests, a stand consisting of a broad-leaved, nitrogen-fixer Alnus japonica and a stand of the needle-leaved Picea glehnii Masters, in eastern Hokkaido, Japan.To clarify maintenance mechanisms, we studied the forest profile, water level, groundwater and precipitation chemistry, seedling establishment patterns in relation to microhabitats, and seed migration.The profile of groundwater level insufficiently explained the abrupt boundary formation, while the groundwater che-mistry differed significantly between the two forests;i.e., EC, Na+, K+, Mg2+, Ca2+ and Cl-were higher in P.glehnii forest and pH was lower.Precipitation in P.glehnii forest contained richer Na+, Ca2+ and Cl-, indicating that the differences in surface-water chemistry were mostly derived from precipitation.Solar radiation was less than 2.2 MJ·m-2·d-1 on P.glehnii forest in late June, while that was patchily distributed in A.japonica forest with a range from 1.0 to 3.7 MJ·m-2·d-1.Moss cover on the soil surface, most of which were made of Sphagnum spp., was 60% in P.glehnii forest, but was 10% in A.japonica forest.Surface water chemistry represented by pH was considered to determine the development of Sphagnum moss.About 70% of P.glehnii seedlings < 1.3 m in height established on moss cover.Seed-sowing experiments suggested that seed germination and seedling survival for both species were significantly higher in P.glehnii forest.Therefore, the regeneration of P.glehnii in A.japonica forest was negligible, owing to the paucity of favorable microhabitats and low seedling establishment.A.japonica regenerated only by resprouting, and the seedlings were few in both forests.In addition, A.japonica seed migration into the P.glehnii forests was greatly restricted, and low solar radiation in the P.glehnii forest contributed to low seedling survival.Based on those results, we concluded that Picea glehnii and Alnus japonica could develop distinct and selfish environments being unsuitable for the other species and inhibit natural afforestation of another species each other by excluding invasion.

Environmental and biological factors affecting the abundance of Prosopis flexuosa saplings in the central-west Monte of Argentina

Background:Trees and forests in drylands help mitigate the challenges through provision of economic products and vital environmental services such as habitat for biodiversity,prevention of erosion and desertification,regulation of water,microclimate,and soil fertility.The condition and changes in dry forests can be assessed by using ecological indicators able to quantify spatial and temporal changes in vegetation.One of the ways to determine the condition of the forest is to study the dominant tree species and its regeneration.Our study aimed to assess whether the abundance of Prosopis flexuosa saplings is affected by environmental and biological factors.Results:To evaluate the first variables we used data from remote sensing such as satellite images and Aster Global Digital Model(GDEM).The second set of variables was about exotic and native ungulates and we used feces of these animals and camera traps to take data.We found that sapling abundance related positively to sandy substrates and negatively to Wetness Index.On the other hand,in relation to biological variables,the abundance of saplings was positively affected by density of adult trees and by number of seeds dispersed by equines,but space use by Lama guanicoe had a negative relationship with saplings.This research shows that P.flexuosa saplings are benefited from sandy substrates and the conditions around adult trees.In addition to this,we found that exotic ungulates in low densities have neutral(i.e.cattle)or positive(i.e.equines)effects on sapling abundance.Conclusions:Based on these findings,we conclude that regeneration of the population of P.flexuosa in our study area has no major problems.In addition,we corroborated that the presence of exotic and domestic ungulates in low densities does not have deleterious consequences for saplings of the dominant tree,P.flexuosa.

Effects of active molecules of Korean pine seed on rodent health and implications for forest regeneration

After maturation, Korean pine (Pinus koraiensis Siebold & Zucc.) seeds often cannot disperse to reach a suitable germination site. It is therefore difficult to naturally regenerate by itself and relies on animal dispersal. Squirrels hoard pine seeds as winter food and Korean pine seeds stored for overwintering might become the source of regeneration of the species. From field observations, the pine seeds are the food preference for squirrels during autumn in the Lesser Khingan Mountains in Northeast China. Such preference by squirrels has been attributed to high seed energy content and the ease of seed storage. However, it may also be expected from nutritional aspects that a coevolutionary relationship between squirrels and Korean pine species could be partially explained by the effect of active seed components and their physiological regulatory effects on squirrels. To test this hypothesis, control experiments were carried out to examine the modulatory effects of Korean pine nut oil (PNO) on intestinal microbiota, inflammatory profile and oxidative stress in mice. The results showed that, compared with mice fed a high-fat diet, PNO significantly improved the physical and the healthy state of mice. Histological analysis of the liver and epididymal fat tissue showed that PNO alleviated liver and adipocyte lesions, and inflammation caused by high-fat diets. PNO also significantly decreased atherosclerotic index and ameliorate serum lipid accumulation to prevent cardiovascular disease, which effect the positive control SG group. Moreover, PNO elevated superoxide dismutase and glutathione peroxidase enzyme activities and reduced malondialdehyde levels in the serum. 16S rRNA sequencing showed that PNO restored intestinal microbiota composition, significantly increasing the relative abundance of Lactobacillus and Akkermansia bacteria. These results suggest that Korean pine seeds not only provide adequate fat, protein and energy for squirrels, but also promote physical health and improve body immunity.