西双版纳热带季节雨林145个树种繁殖体特征

分析了西双版纳热带季节雨林20公顷动态监测样地中145个树种的繁殖体特征。结果表明：雨季散布的种类最多（71.03%）,在雾凉季及干热季散布的种类相对较少;果实类型以核果,蒴果,浆果居多,黑色、黄色、褐色果实最为常见;动物散布的种类最多（56.55%）,其次为机械散布,独立散布,风力散布;大种子树种（种子最大长度〉10mm）较占优势（53.10%）;树种单粒种子重量从2.3×10^-5～22.29g不等,但76.55%的种子的重量集中在0.01～10g之间;干热季散布的种子平均重量显著高于雨季和雾凉季;独立散布的种子重量最大,风力散布的种子重量最小,而机械弹射的种子重量和动物散布的种子重量之间差异不显著;树种的成年个体最大胸径与种子重量之间存在显著正相关。     

不同年际间异子蓬种子大小、萌发能力及结实格局

异子蓬(Borszczowia aralocaspica)为中亚荒漠特有种,在我国仅分布于新疆,其果实具有二型性。对同一生长地2006、2007、2008年异子蓬种子的大小、萌发特性及结实格局进行比较,结果表明:(1)年份和种子类型对种子大小和重量均有显著影响(P<0.05)。(2)2种类型种子具有不同的萌发行为,褐色种子萌发率高(>90%),萌发速度快,而黑色种子萌发率低(2006年的萌发率为31%),萌发速度慢;2种类型种子的萌发指数在不同年际间均差异显著。(3)不同年际间,种子总数、褐色种子数、黑色种子数均具有极显著差异(P<0.001),且随个体的增大黑色种子的比例逐渐减小,褐色种子的比例逐渐增大,并且黑色种子数目均高于褐色种子数目。该研究为深入认识异型种子的生态适应对策提供理论基础。     

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

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

Ecological correlates of seed desiccation tolerance in tropical African dryland trees

In the tropics, species with recalcitrant or desiccation-sensitive, Type III seeds are largely restricted to regions with comparatively high rainfall, because desiccation-induced seed death will be minimal in these environments. However, species with recalcitrant seeds do occur in drylands, although little is known about ecological adaptations to minimize seed death in these environments. Here we present data for the seed desiccation tolerance of 10 African dryland species and examine the relationships between seed size, rainfall at the time of seed shed, and desiccation tolerance for these and a further 70 species from the scientific literature. The combined data set encompasses species from 33 families. Three species (Syzygium cumini, Trichilia emetica, and Vitellaria paradoxa) had desiccation-sensitive seeds, and the remaining seven species investigated were desiccation-tolerant. The desiccation-sensitive species had large (>0.5 g) seeds, germinated rapidly, and had comparatively small investments in seed physical defenses. Furthermore, seed was shed in months of high rainfall (>60 mm). In comparison, for species with desiccation-tolerant seeds, seed mass varied across five orders of magnitude, and seed was shed in wet and dry months. Although infrequent in dryland environments (approximately 11% of the species examined here), species with desiccation-sensitive seeds do occur; large size, rapid germination, and the timing of dispersal all reduce the likelihood of seed drying. Furthermore, desiccation-sensitivity may be advantageous for large-seeded species by increasing the efficiency of resource use in seed provisioning.     

Frugivory and Seed Dispersal by Four Species of Primates in Madagascar's Eastern Rain Forest1

In the unique faunal assemblage of the Malagasy rain forest, lemurs appear to play particularly important roles as seed-dispersing frugivores. A three-month study of feeding ecology and seed dispersal by four species of lemurs in Madagascar's eastern rain forest found that three species, Eulemur rubriventer, Eulemur fulvus, and Varecia variegata were seed dispersers, and the fourth, Propithecus diadema, was a seed predator. In germination trials, seeds passed by lemurs sprouted significantly faster and in greater numbers than those not passed by lemurs. Analysis of fruit morphologies of 69 local plant taxa producing fleshy fruits during the study period found that these fruits fell into two well-defined color categories that correlated significantly with fruit size. Seventy seven percent of fleshy fruits greater than 10 mm in diameter were colored green, brown, tan, purplish, or black, while all fruits less than 10 mm in diameter were colored red, yellow, orange, pink, blue, or white. Three introduced exotic plant species provided exceptions to this pattern, producing fruits which were larger than 10 mm and pink or orange. Fruits chosen by the primates in this study were usually larger than 10 mm in diameter and were in nearly all cases colored green, brown, tan, purplish, red, or some combination of these colors. Morphological traits shared by fruits of multiple plant taxa in the diets of seed-dispersing lemurs suggest possible coevolved relationships between Malagasy rain forest plants and lemurs.     

Frugivory and Seed Dispersal by Northern Pigtailed Macaques (Macaca leonina), in Thailand

Tropical rain forest conservation requires a good understanding of plant–animal interactions. Seed dispersal provides a means for plant seeds to escape competition and density-dependent seed predators and pathogens and to colonize new habitats. This makes the role and effectiveness of frugivorous species in the seed dispersal process an important topic. Northern pigtailed macaques (Macaca leonina) may be effective seed dispersers because they have a diverse diet and process seeds in several ways (swallowing, spitting out, or dropping them). To investigate the seed dispersal effectiveness of a habituated group of pigtailed macaques in Khao Yai National Park, Thailand, we examined seed dispersal quantity (number of fruit species eaten, proportion in the diet, number of feces containing seeds, and number of seeds processed) and quality (processing methods used, seed viability and germination success, habitat type and distance from parent tree for the deposited seeds, and dispersal patterns) via focal and scan sampling, seed collection, and germination tests. We found thousands of seeds per feces, including seeds up to 58 mm in length and from 88 fruit species. Importantly, the macaques dispersed seeds from primary to secondary forests, via swallowing, spitting, and dropping. Of 21 species, the effect of swallowing and spitting was positive for two species (i.e., processed seeds had a higher % germination and % viability than control seeds), neutral for 13 species (no difference in % germination or viability), and negative (processed seeds had lower % germination and viability) for five species. For the final species, the effect was neutral for spat-out seeds but negative for swallowed seeds. We conclude that macaques are effective seed dispersers in both quantitative and qualitative terms and that they are of potential importance for tropical rain forest regeneration.     

Patterns of Seed Size,Germination and Seed Viability of Tropical Tree Species in Southern India1

Seed weight, days to germination and seed viability were observed for 99 species growing in the Western Ghats of Karnataka, India. Seed size was strongly correlated with days to germination; smaller seeds germinated faster than larger seeds. Species which flowered during the rainy season had lighter seeds than species which flowered during the dry season. It was also found that seed size and viability of seeds were related to the season of fruiting. Species which fruit during the rainy season had heavier seeds and shorter viability than species which fruit during the dry season. These flowering and fruiting patterns and varying seed sizes are argued to be adaptations to the time of dispersal, time of moisture availability in the habitat and seedling survival.     

异子蓬二型种子的萌发与休眠特性及其生态适应

异子蓬为中亚荒漠的特有种,其果实为胞果,花被片在结果时宿存包被果实形成浆果状的散布单位.对异子蓬的散布单位、果实形态进行比较观察,并在5/15℃、5/25℃、15/25 ℃(暗/光=12h/12h)3个温变周期下进行种子萌发实验,结果表明:(1)异子蓬的散布单位绿色、浆果状,有大小两种形态;大小两种散布单位内包被的果实在形状、大小、颜色上存在着明显差异.(2)大的散布单位内包被的果实圆形,扁平,褐色,无光泽,直径(2.64±0.03) mm,重量(3.68±0.04) mg;小的散布单位内包被的果实双凸镜形,黑色,有光泽,直径(2.40±0.04) mm,重量(2.86±0.06) mg.(3)褐色种子在3个温变周期下的萌发率都在81%以上,萌发速度快,而黑色种子萌发率低,萌发慢,具有休眠现象.(4)划破种皮及低温层积处理可显著提高黑色种子在3个温变周期下的萌发率,延长储存时间也可有效地促进黑色种子的萌发,表明黑色种子处于非深度生理休眠状态.异子蓬产生的两种不同类型的种子及其在时间和空间上的萌发差异对荒漠异质环境具有重要的适应意义.     

Fruit Bats (Chiroptera: Pteropodidae) as Seed Dispersers and Pollinators in a Lowland Malaysian Rain Forest1

The aims of this study were to (1) characterize the food resources exploited by fruit bats (Pteropodidae) within an old‐growth Malaysian dipterocarp forest, (2) test the viability of the seeds they disperse, and (3) provide an estimate of the proportion of trees that are to some degree dependent upon bats for seed dispersal and/or pollination. Fruit species exploited by bats could be distinguished from those eaten by birds largely on the basis of color (as perceived by human beings). Bat‐dispersed fruits were typically inconspicuous shades of green–yellow or dull red–brown, whereas fruits eaten by birds were generally bright orange to red. Dietary overlap between bats and nonflying mammals was relatively high. In contrast to primates and squirrels, which were major seed predators for several of the plant species under investigation, fruit bats had no negative impact on seed viability. A botanical survey in 1 ha of old‐growth forest revealed that 13.7 percent of trees (?15 cm girth at breast height) were at least partially dependent upon fruit bats for pollination and/or seed dispersal.     

Patterns of Seed Dispersal and Dispersal Failure in a Hawaiian Dry Forest Having Only Introduced Birds

Dry forests are among the most endangered natural communities in the Hawaiian Islands. Most have been reduced to isolated trees and small forest fragments in which native tree species reproduce poorly. The replacement of native birds by introduced generalists may be contributing to dry forest decline through modification of seed dispersal patterns. To document seed dispersal by introduced birds, we conducted foraging observations on fleshy-fruited trees and measured seed rain under trees and in adjacent open areas for 1 year in a dry forest dominated by native trees. Although trees covered only 15.2 percent of the study area, 96.9 percent of the bird-dispersed seeds were deposited beneath them. The Japanese white-eye (Zosterops japonicus) was the principal dispersal agent. Among bird-dispersed seeds, those of the invasive tree Bocconia frutescens accounted for 75 percent of all seeds collected beneath trees (14.8 seeds/m²/yr) and the invasive shrub Lantana camara accounted for 17 percent. Although nearly 60 percent of the reserve's native woody species possess fleshy fruits, introduced birds rarely disperse their seeds. Native trees accounted for <8 percent of all bird-dispersed seeds and are consequently experiencing dispersal failure by falling directly under parent trees. Smaller-seeded non-native plants, in contrast, may be benefiting from dispersal by introduced birds. Current dispersal patterns suggest that these readily disseminated non-native plants may eventually replace the remaining native flora.     

Frugivory and Seed Dispersal by Brown Lemurs in a Malagasy Tropical Dry Forest

In the Ankarafantsika tropical dry forest (northwestern Madagascar), the common brown lemur (Eulemur fulvus fulvus) is the largest frugivore and probably the sole disperser of large‐seeded plants (seed diameter > 10 mm). To investigate seed dispersal by this primate, I recorded the feeding activities of a troop; also conducted fecal analyses, germination trials on defecated seeds, and a vegetation survey over 1 yr (beginning Dec 2006). Brown lemurs mostly consumed fruit (68%). The fruit of Vitex beraviensis was the most exploited resource (21% of total feeding time). Among dung samples, 1126 contained intact seeds of 70 plant species, with a median of six seeds and two species per sample. These data indicate that the brown lemur population dispersed approximately 9854 seeds/km²/d. Although the number of annually defecated seeds was overwhelmingly the largest in Grewia triflora, many of the small seeds were often clumped in dung piles. In contrast, large seeds of V. beraviensis occurred in the largest number of dung samples. The rate and time of seed germination in V. beraviensis were improved by passage through brown lemur guts. Therefore, V. beraviensis may readily establish seedlings in sites of brown lemur fecal deposition. Vitex beraviensis and brown lemurs are probably involved in a strong mutualism. Twenty‐three large‐seeded plants were probably dependent on brown lemurs for seed dispersal and some of these species were common trees in the forest. Maintenance of these key plant–animal interactions will probably contribute to the conservation of species diversity and intact regeneration of the Ankarafantsika forest.     

Frugivory by the fish Brycon hilarii (Characidae) in western Brazil

Frugivory and seed dispersal have been poorly studied in Neotropical freshwater fishes. We studied frugivory and seed dispersal by the piraputanga fish (Brycon hilarii, Characidae) in the Formoso River, Bonito, western Brazil. We examined the stomach contents of 87 fish and found the diet of piraputanga consisted of 24% animal prey (arthropods, snails, and vertebrates), 31% seeds/fruits and 45% other plant material (algae/macrophytes/leaves/flowers). The piraputangas fed on 12 fruit species, and were considered as seed dispersers of eight species. Fruits with soft seeds larger than 10 mm were triturated, but all species with small seeds (e.g. Ficus, Psidium) and one species with large hard seed (Chrysophyllum gonocarpum) were dispersed. Piraputangas eat more fruits in the dry season just before the migration, but not during the spawning season. Fish length had a positive relation with the presence of fruits in their guts. The gallery forest of the Formoso River apparently does not have any plant species that depend exclusively on B. hilarii for seed dispersal because all fruit species are also dispersed by birds and mammals. Based on seed size and husk hardness of the riparian plant community of Formoso River, however, the piraputangas may potentially disperse at least 50% of the riparian fleshy fruit species and may be particularly important for long-distance dispersal. Therefore, overfishing or other anthropogenic disturbances to the populations of piraputanga may have negative consequences for the riparian forests in this region.     

Do rivers function as corridors for plant dispersal?

Abstract. We evaluated the importance of dispersal for species frequencies and distribution by comparing dispersal properties of vascular plant species with their frequencies along river banks. We assumed that species with long-floating seeds would be more frequent than species with short-floating seeds. We compiled data on frequencies of vascular plants and their dispersal properties from ten rivers in northern Sweden and compared these with boreal forests and grasslands in the same region. In all rivers, but in none of the reference areas, there was a positive relationship between floating capacity and frequency of species. A comparison of floating capacity between species with and without certain dispersal devices showed that seeds of vegetatively dispersed species had higher floating capacities than other seeds. For other dispersal categories (animal and wind dispersal), floating time did not differ from contrast groups. The results indicate that water dispersal has a certain role in structuring the riparian flora, and provide a basis for explaining species distribution patterns from dispersal characteristics. They also suggest that continuous river corridors are important for maintaining regional biodiversity.     

Seed dispersal by rivers in tropical dry forests: An overlooked process in tropical central Mexico

Aims

Rivers are important corridors for the movement, migration and dispersal of aquatic organisms, including seeds from riparian plants. Although tropical dry forests (TDF) are among the most extensive and floristically rich ecosystems of tropical habitats, and the most globally endangered ecosystem, less attention has been given to riparian corridors within this ecosystem. Although most TDFs manifest peak seed dispersal during dry seasons, we hypothesized that riparian corridors may show a dispersal peak during the rainy season, due to an anticipated ‘sweep or drag effect’, resulting from river overflow and bank erosion. Our main aims were to investigate whether there were any differences in the seed communities transported by the river to sites in rainy as opposed to dry seasons, and to evaluate any possible relationship between the riparian seed community and river flow.

Location

Amacuzac River, drainage of the Balsas basin, State of Morelos, Mexico.

Methods

To evaluate the above assumption, we associated Amacuzac River flow with the number of species and seeds dispersed by water. We also characterized and evaluated differences between seed communities transported by the river during the rainy and dry seasons, and between four different sites located along the river. We used univariate and ordination NMDS techniques to evaluate patterns between seasons at the community level.

Results

Forty‐five plant species were identified from 909 seeds collected from the river. The composition of riparian seed communities was markedly different between seasons but not between sites. Seed abundances were significantly higher in the rainy than in the dry season and varied between sites. Seed species diversity in the river (H’ = 1.6–1.9) showed no significant differences between seasons or sites, but species assemblages and dominance varied according to season. Ordination techniques and subsequent fitting analyses showed that seed species composition was positively associated with river flow.

Conclusions

Seed dispersal patterns generated by rivers are significant mechanisms for structuring the composition and distribution of the riparian plant community in Mexican TDF. Varying species assemblages and seed abundance dispersed by the river throughout the year is a relevant and until now unknown consequence that may affect the dynamics and composition of riparian plant communities in this region. This study initiative will promote new avenues of research regarding plant establishment and succession.     

What are the consequences of ant–seed interactions on the abundance of two dry-fruited shrubs in a Mediterranean scrub?

Strong interactions between dry-fruited shrubs and seed-harvesting ants are expected in early successional scrubs, where both groups have a major presence. We have analysed the implications of the seed characteristics of two dry-fruited shrub species (Coronilla minima and Dorycnium pentaphyllum) on seed predation and dispersal mediated by harvester ants and the consequences of these processes on spatio-temporal patterns of plant abundance in a heterogeneous environment. We found that large C. minima seeds were collected much more (39%) than small D. pentaphyllum seeds (2%). However, not all of the removed seeds of these plant species were consumed, and 12.8% of the seeds were lost along the trails, which increased dispersal distances compared with abiotic dispersal alone. Seed dropping occurred among all microhabitats of the two plant species, but especially in open microhabitats, which are the most suitable ones for plant establishment. The two plant species increased their presence in the study area during the study period: C. minima in open microhabitats and D. pentaphyllum in high vegetation. The large size of C. minima seeds probably limited the primary seed dispersal of this species, but may have allowed strong interaction with ants. Thus, seed dispersal by ants resulted in C. minima seeds reaching more suitable microhabitats by means of increasing dispersal distance and redistribution among microhabitats. In contrast, the smaller size of D. pentaphyllum seeds arguably allows abiotic seed dispersal over longer distances and colonization of all types of microhabitats, although it probably also limits their interaction with ants and, consequently, their redistribution in suitable microhabitats. We suggest that dyszoochory could contribute to the success of plant species with different seed characteristics in scrub habitats where seeds are abundantly collected by seed-harvesting ants.     

Frugivory and Seed Dispersal by the Lowland Tapir Tapirus terrestris in the Peruvian Amazon

The lowland tapir Tapirus terrestris is the largest herbivore in the Neotropics and feeds on a large quantity of fruits, often ingesting the seeds and defecating them intact. Seed dispersal by the lowland tapir in the southwestern Amazon was studied by examining seeds from 135 dung samples collected between 2005 and 2007. Seeds of a total of 122 plant species were identified, representing 68 genera and 33 families. The species accumulation curve showed that more species can be expected with further sampling. Many species (45%) were only encountered once, and only 10 percent of all species were found in >10 samples, indicating that the lowland tapir is an opportunistic forager. Seed diversity showed a clear seasonal pattern and was highly correlated with fruit availability. Seed diameter ranged from <1 to 25 mm with 81 percent <10 mm diam. The size distribution of seeds found in lowland tapir dung generally followed that of seeds found in the forest, but had a lower proportion of seeds in the smallest size class (<2.5 mm) and a larger proportion found in the largest size class (20–25 mm). The diversity of seeds encountered in dung of the lowland tapir in this study was much higher than in previous studies. We conclude that the lowland tapir is a potential disperser for a large number of plant species, including many that previously have been thought to be dispersed only by large primates.     

A multi-scale test for dispersal filters in an island plant community

Constraints on plant distributions resulting from seed limitation (i.e. dispersal filters) were evaluated on two scales of ecological organization on islands off the coast of British Columbia, Canada. First, island plant communities were separated into groups based on fruit morphology, and patterns in species diversity were compared between fruit‐type groups. Second, abundance patterns in several common fleshy‐fruited, woody angiosperm species were compared to species‐specific patterns in seed dispersal by birds. Results from community‐level analyses showed evidence for dispersal filters. Dry‐fruited species were rare on islands, despite being common on the mainland. Island plant communities were instead dominated by fleshy‐fruited species. Patterns in seed dispersal were consistent with differences in diversity, as birds dispersed thousands of fleshy‐fruited seeds out to islands, while dry fruited species showed no evidence of mainland‐island dispersal. Results from population‐level analyses showed no evidence for dispersal filters. Population sizes of common fleshy‐fruited species were unrelated to island isolation, as were rates of seed dispersal. Therefore, island isolation distances were not large enough to impose constraints on species’ distributions resulting from seed limitation. Rates of seed dispersal were also unrelated to island area. However, several species increased in abundance with island area, indicating post‐dispersal processes also help to shape species distributions. Overall results suggest that seed dispersal processes play an important role in determining the diversity and distribution of plants on islands. At the community‐level, dry‐fruited species were seed limited and island communities were instead dominated by fleshy‐fruited species. At the population‐level, common fleshy‐fruited species were not seed limited and showed few differences in distribution among islands. Therefore, although evidence for dispersal filters was observed, their effects on plant distributions were scale‐dependent.     

Seed Dispersal Modes of the Sandstone Plateau Vegetation of the Middle Caquetá River Region,Colombian Amazonia1

We characterized the dispersal spectra and phenology of 298 vascular plant species of the sandstone plateaus of Colombian Amazonia. Dispersal modes were determined by the morphology of dispersion units, personal observations on fruit consumption, and an extensive literature review. We obtained the number of species per dispersal mode for the sandstone plateaus and for two recognized vegetation types: open‐herbaceous vegetation and low forest‐shrub vegetation. Dispersal modes were assigned to 295 plant species. Animals dispersed the highest percentage of species (46.6%), while the percentage of autochorous and anemochorous species was 29.4 and 23 percent, respectively. The dispersal spectrum of the low forest‐shrub vegetation type, based on the coverage of every species, showed that percentages of anemochorous (40.2%) and zoochorous species (37.8%) were similar. Autochory was the most important seed dispersal mode of the open‐herbaceous vegetation (60%). Birds were the principal group of potential dispersers (58.9%) of zoochorous species and reptiles the least important. We found two marked fruiting peaks, one from the end of the dry season to the beginning of the wet season and the second one from the beginning to the middle of the dry season. Our results showed that besides the differences in the vegetation structure and floristic composition between the sandstone plateaus and the adjacent tall forest, there also exist differences in the dispersal spectra and the fruiting rhythms.     

Seed dispersal spectra: a comparison of temperate plant communities

Abstract. We compare the dispersal spectra of diaspores from varied plant communities in Australia, New Zealand, and North America, assigning dispersal mode to each diaspore type on the basis of apparent morphological adaptations. Species with ballistic and external dispersal modes were uncommon in most communities we surveyed. Ant dispersal was also rather uncommon, except in some Australian sclerophyll vegetation types. The frequency of vertebrate dispersal ranged up to 60% of the flora, the highest frequencies occurring in New Zealand forests. Wind dispersal ranged as high as 70% of the flora, with the highest values in Alaska, but usually comprised 10–30% of the flora. Many species in most communities had diaspores with no special morphological device for dispersal. Physiognomically similar vegetation types indifferentbiogeographic regions usually had somewhat dissimilar dispersal spectra. The frequency of dispersal by vertebrates often increased and the frequency of species with no special dispersal device decreased along gradients of increasing vertical diversity of vegetation structure. Elevation and moisture gradients also exhibited shifts in dispersal spectra. Within Australia, vertebrate- and wind-dispersal increased in frequency along a soil-fertility gradient, and dispersal by ants and by no special device decreased. Habitat breadths (across plant communities) and microhabitat breadths (within communities) for species of each major dispersal type did not show consistent differences, in general. Ant-dispersed species often had lower cover-values than other species in several Australian vegetation types. We discuss the ecological bases of these differences in dispersal spectra in terms of the availability of dispersal agents, seed size, and other ecological constraints. Seed size is suggested to be one ecological factor that is probably of general relevance to the evolution of dispersal syndromes.     

Seed Dispersal by Birds and Bats in Lowland Philippine Forest Successional Area

In the tropical forests of SE Asia, only a few studies have dealt with the role animal dispersal plays in early forest succession and rehabilitation, and a comparison of bird and bat dispersal is even rarer. We investigated seed dispersal by birds and bats in a successional area in the lowland dipterocarp forest of the Subic Watershed Forest Reserve (SWFR) in Luzon Island, Philippines. Using pairs of day and night traps, we collected seeds during 3 mo of wet season and 3 mo of dry season in a 1.2-ha study site. Bird-dispersed seeds predominated over those dispersed by bats in terms of both seed abundance and number of seed species. The most abundant endozoochorous seed species were significantly biased toward either bird or bat dispersal. Birds and bats appeared to compete more strongly for fruit resources during the dry season than during the wet season, and bats responded more to changes in the seasons than birds did. GLM analyses showed that the factor that had the strongest influence on overall seed distribution was the number of fleshy-fruited trees surrounding the traps, and that the distribution pattern of day-dispersed seeds was affected by more physical factors (number of trees, size of trees, presence of fleshy-fruited and conspecific trees) in the study site than the pattern of night-dispersed seeds were. Given that birds are the more important dispersers in the study site, restoration efforts in SWFR might benefit by focusing on attracting these dispersers into its degraded habitats.