Fruit Removal Rates Research Articles

Drivers of intraspecific variation in seed dispersal can differ across two species of fleshy‐fruited savanna plants

AbstractVarious factors may mediate the visitation of frugivores to fruiting plants, which can dictate the quantum of seeds removed (dispersed) away from the parent plant. Past studies have laid emphasis on species‐specific factors and environmental contexts that frugivores may use as cues to make foraging decisions and differentially visit various plant species. However, differences in plant traits (intrinsic factors) and local environmental contexts (extrinsic factors) can influence the diversity and abundance of frugivores that visit individual plants of the same species, resulting in intraspecific variation in seed dispersal. We observed individuals of two co‐fruiting plant species with morphologically similar fruits—Naringi crenulata and Ziziphus oenopolia—for 134 h and examined the influence of fruit crop size, plant height, and fruiting neighborhood on the diversity of visiting avian frugivores and quantum of fruit removal for individual plants. We found that despite their similarity in fruits and sharing of a similar set of frugivore species, the two plant species differed in how they attracted frugivores, with consequences for fruit removal rates. Fruit crop size was an important determinant of fruit removal for N. crenulata¸ while plant height led to greater visitation and fruit removal for Z. oenopolia. We discuss potential reasons for the difference in frugivore visitation and fruit removal for the two plant species. Our results support a growing body of evidence that intraspecific variation in seed dispersal is pervasive and highly context‐dependent, and describe frugivore interactions of two plant species from an understudied tropical savanna.

Frugivory and seed predation of fishtail palm (Caryota mitis Lour.) on the remote oceanic island of Narcondam, India

Abstract Oceanic islands, due to their evolutionary history and isolation, play a dual role of having high endemicity and being vulnerable to extinctions, with most known extinctions occurring on islands. Plant–animal interactions are particularly important on islands, as island systems generally have low redundancy and are more vulnerable to disruption either via extinction or by invasive species. Here, we examined the fruit removal and seed predation of a keystone palm, Caryota mitis, on Narcondam, a remote oceanic island. The island endemic Narcondam Hornbill (Rhyticeros narcondami) was the sole seed disperser of the palm (90 hours; N = 15 trees), with mean (± SE) visitation rate being 0.23 (± 0.06) individuals per hour and fruit removal rates of 3.5 (± 1.5; range: 0–16) fruits per visit, indicating a lack of redundancy in seed dispersal of the palm on this island. Whereas the invasive rodent, Rattus cf. tiomanicus, was the sole predator of palm seeds (N = 15 individual fruiting palms, 416 trap nights). Overall, 17.1% of the seeds placed (N = 375 seeds) were removed. Seeds placed under and away from the canopy, and at different densities (2 plots with 10 seeds each; 1 plot with 5 seeds, respectively), showed similar removal rates. This indicates density-independent seed predation and the lack of safe regeneration sites for Caryota mitis, with potential deleterious effects on subsequent stages of the ‘seed dispersal cycle’. Here, from a data-deficient site, we provide baseline information on the plant–frugivore interaction of a keystone palm and the potential impacts of an invasive rodent.

Evaluation of the Potential Seed Dispersal Effectiveness of Malus sieversii (Lebed.) M. Roem. by Cattle

The success of plant reproduction is highly dependent on effective seed dispersal. This study aimed to evaluate the potential seed dispersal effectiveness of cattle for Malus sieversii. The impact of cattle on the dispersal quantity and dispersal quality of M. sieversii seeds was explored based on camera trapping, GPS tracking, and germination trials. The results showed that, on average, cattle visited M. sieversii trees 477.33 times during a two-month observation period. Out of these visits, 315 were specifically for fruit removal. The fruit removal rate per cattle visit was as high as 96.67%. Additionally, cattle were able to disperse M. sieversii seeds up to a maximum distance of 533.67 m, with an average dispersal distance of 134.62 m. The average distance of cattle movement was recorded as 176.95 m/h, with peak activity observed during 11:00–13:00 and 19:00–21:00. The germination rate of M. sieversii seeds that passed through the digestive tract of cattle was significantly higher than that of control seeds. Finally, the emergence rate and survival rate of seeds dispersed by cattle to forest edges and gaps were significantly higher than those dispersed to understory. These findings suggest that cattle can serve as effective long-distance dispersers of M. sieversii seeds and may play a crucial role in the regeneration and expansion of M. sieversii populations in the Ili Botanical Garden.

Spillover of avian seed dispersers between secondary forests and degraded areas in a tropical island

Seed arrival to degraded areas often represents a limiting factor to forest regeneration, but seed-dispersing birds able to move into such areas may help to overcome such constraint. As the number of degraded areas prone to regeneration is increasing in the tropics, it is important to know which bird species and associated traits make such spillover movements. We studied the interactions between frugivorous birds and eight plant species in contiguous degraded and secondary forest areas in a Brazilian land-bridge island, evaluating the potential of avian cross-habitat spillover to disperse seeds to degraded areas and thus contribute to their vegetation recovery. We recorded 21 and 17 bird species removing fruits in degraded areas and secondary forests, respectively. Avian communities dispersing seeds in both habitats are dominated by habitat generalist species. Visitation and fruit removal rates did not differ between the two habitats. Avian cross-habitat spillovers were more frequent from secondary forests to degraded areas than the reverse. A few bird species (Dacnis cayana, Elaenia flavogaster, and Turdus spp.) stood out in the spillover between habitats due to their generalist habitat occupancy and capacity for foraging in disturbed areas. We likewise identified the plants that most attracted birds (including an exotic palm, Livistona chinensis) so as to pinpoint the plant species that may occasionally be the focus of management actions to enhance the arrival of seeds to degraded areas. We conclude that the spillover dynamics reported herein shed some light on how tropical forest regeneration could benefit from native species’ spatial behaviour, offering a biological alternative to overcome practical issues, such as seed limitation in degraded environments.

基于能量利用率的油茶果机械化采摘试验与分析

In order to use the resonance principle for vibratory picking of Camellia oleifera fruit, the frequency sweep tests were carried out on the fruiting branches of Camellia oleifera trees. The results showed that the acceleration response of fruit-bearing branches had good consistency. The use of fruit removal rate alone to evaluate the picking effect is not reliable, and the introduction of energy utilization to evaluate the vibration picking effect is significant. The best results were a vibration frequency of 8 Hz and an excitation time of 10 s. The fruit removal rate was 88.12% and the energy utilization rate was 36.72%. Compared with the traditional fruit shedding rate, the application of energy utilization rate to evaluate the picking effect can improve the reliability of the results and reduce the energy loss.

Fruit secondary metabolites alter the quantity and quality of a seed dispersal mutualism.

Plant secondary metabolites are key mechanistic drivers of species interactions. These metabolites have primarily been studied for their role in defense, but they can also have important consequences for mutualisms, including seed dispersal. Although the primary function of fleshy fruits is to attract seed-dispersing animals, fruits often contain complex mixtures of toxic or deterrent secondary metabolites that can reduce the quantity or quality of seed dispersal mutualisms. Furthermore, because seeds are often dispersed across multiple stages by several dispersers, the net consequences of fruit secondary metabolites for the effectiveness of seed dispersal and ultimately plant fitness are poorly understood. Here, we tested the effects of amides, nitrogen-based defensive compounds common in fruits of the neotropical plant genus Piper (Piperaceae), on seed dispersal effectiveness (SDE) by ants, which are common secondary seed dispersers. We experimentally added amide extracts to Piper fruits both in the field and lab, finding that amides reduced the quantity of secondary seed dispersal by reducing ant recruitment (87%) and fruit removal rates (58% and 66% in the field and lab, respectively). Moreover, amides not only reduced dispersal quantity but also altered seed dispersal quality by shifting the community composition of recruiting ants (notably by reducing the recruitment of the most effective disperser by 90% but having no detectable effect on the recruitment of a cheater species that removes fruit pulp without dispersing seeds). Although amides did not affect the distance ants initially carried seeds, they altered the quality of seed dispersal by reducing the likelihood of ants cleaning seeds (67%) and increasing their likelihood of ants redispersing seeds outside of the nest (200%). Overall, these results demonstrate that secondary metabolites can alter the effectiveness of plant mutualisms, by both reducing mutualism quantity and altering mutualism quality through multiple mechanisms. These findings present a critical step in understanding the factors mediating the outcomes of seed dispersal and, more broadly, demonstrate the importance of considering how defensive secondary metabolites influence the outcomes of mutualisms surrounding plants.

Certified forest management and conservation of medium and large-sized mammals: biodiversity, trampling, browsing and seed removal in the Argentine Austral Yungas

Timber extraction is one of the most widespread human activities in forested environments, and subsequent environmental degradation and impacts on wildlife have been extensively studied. Reduced impact logging under certification standards could help reconcile forest production with biodiversity conservation. However, whether this is a convenient strategy for the conservation of the medium and large-sized mammal assemblage of the Argentine Austral Yungas remains unknown. Here, we compared species richness, diversity and composition, sign frequency and species identity of medium and large mammals considering body mass and trophic guilds, as well as three mammal-plant interactions (seedling trampling, plant browsing and fruit removal) between an area under logging certification and a similar unlogged area (control). Our results indicate that, 3–4 years after logging stopped, 16 of the 32 variables analyzed showed no changes between the logged area and the control (species composition, richness and 2 diversity indices, frequency of herbivores and omnivores, frequency of 7 species, browsing rate in the 2 lowest strata and trampling rate). In the logged area, we found a higher frequency of medium-sized mammals and 5 mammals species, a higher browsing rate in the upper stratum and a higher fruit removal rate. However, we also found a lower frequency of carnivores, large mammals, and of six mammal species. Although in our study we found certain species-specific differences, with a predominance of generalist species and certain reduced biological interactions in the logged compared to the unlogged area, we propose that forest intervention under responsible management may help to conserve a significant proportion of medium and large-sized mammal diversity of the Argentine Austral Yungas. Effective forest management, which balances the conservation of natural resources with sustainable use, is a crucial solution to preserving biodiversity. Both environmental and governmental organizations should prioritize and support this approach as a way to mitigate deforestation and promote responsible use of our forests.

Significance of seed dispersal by the largest frugivore for large-diaspore trees

How do large-bodied frugivores contribute to seed dispersal of large-diaspore plants? This study examined seed dispersal effectiveness for two large-diaspore tree species, Astrotrichilia asterotricha (AA) and Abrahamia deflexa (AD), in a Madagascan forest. I evaluated fruit removal rates through focal tree observations and factors affecting seedling recruitment up to the 2-year-old seedling stage. I confirmed brown lemur (Eulemur fulvus) as the sole disperser, removing 58.8% and 26.0% of fruits produced by AA and AD. Brown lemurs frequently visited large-crowned AA trees with high density of fallen fruits and more adjacent fruiting trees during seasons with low fruit diversity. Most AA seedlings were removed by predators, although canopy openness slightly improved seedling establishment. Although AD seeds were severely attacked by predators under mother trees, the seedlings survived under dispersal conditions distant from the mother trees, and with low density of diaspores. AD had a higher cumulative probability from fruit removal to seedling recruitment (6.5%) than AA (1.5%) in the first rainy season. This study clarifies the significance of seed dispersal to tree recruitment strategies, which vary among different combinations of tree species and large frugivores, i.e. quantitative dispersal to reach suitable microhabitats, and qualitative dispersal to escape from dangerous zones near mother trees.

Effects of canopy cover on fruiting intensity and fruit removal of a tropical invasive weed

Lantana camara (hereafter, Lantana) is among the worst invasive alien plants spread extensively across Africa, Australia and Asia at an alarming rate, posing significant challenges to conservation of native biodiversity. While, Lantana invasion is widely recognised to be more pronounced in open-canopy habitats (including deciduous forests, forest edges and gaps), the potential role of variation in seed dispersal across habitats varying in overstory canopy cover is poorly understood.Avian frugivores are among primary seed dispersers of the fleshy-fruited Lantana. We monitored 45 Lantana shrubs across a gradient of overstory canopy cover to determine the relationship between fruiting intensity and canopy cover. We watched 80 Lantana shrubs (240 h) across a canopy cover gradient to determine 1) differences in frugivore assemblage visiting Lantana across open- and closed-canopy habitats, 2) drivers of frugivore visitation on Lantana, and 3) relationship between seed disperser visitation rate and overstory canopy cover. We found that Lantana shrubs under low overstory canopy cover had higher fruit abundance than those in high canopy cover. Frugivore assemblage differed between Lantana shrubs in open- versus closed-canopy cover habitats. Drivers of frugivore visitation on Lantana varied across different frugivore species with a greater probability of occurrence of bulbuls (the primary seed dispersers of Lantana) on shrubs under low overstory canopy cover.Visitation rates of the effective seed dispersers were higher on shrubs under low overstory canopy cover. Thus, there was greater chances of dispersal of seeds in habitats with low overstory canopy cover.The study demonstrates variable fruiting intensity and fruit removal rate as a driver of differences in dispersal of seeds across habitats. It highlights greater vulnerability of open habitats to invasion and the need to prioritise Lantana management efforts in open habitats. Anthropogenic activities that lead to canopy openings (e.g. tree lopping and logging) likely facilitate Lantana invasion through greater fruit production and seed dispersal.

Green Fruit Removal Dynamics for Development of Robotic Green Fruit Thinning End-Effector

HighlightsPulling and stem-cutting methods were used for measuring the green fruit removal dynamics.A stem-cutting end-effector prototype was designed, developed, and tested for green fruit removal.No significant correlation was found between the fruit or stem size and the force required for fruit removal.The success rate of the stem-cutting end-effector prototype for all experiments was over 90%.Abstract. Green fruit thinning is one of the most important operations in apple production for obtaining high-quality fruit. Manual thinning is time-intensive, making it impractical for large orchards. Some alternative methods, such as chemical and mechanical thinning, have greatly improved work efficiency, but both methods have drawbacks due to non-selective targeting. Robotic green fruit thinning can potentially be as selective as manual thinning. This study developed an effective end-effector for robotic green fruit thinning. Prior to designing the end-effector, a series of fruit removal dynamics tests were conducted to determine the forces required for robotic thinning using pulling or stem-cutting methods on three different apple cultivars. The overall mean forces for pulling detachment were 24.78 ±0.48 N and 19.91 ±0.55 N when detaching stem from the fruit-end and the spur-end, respectively. The average force required for stem-cutting was 33.6 ±8.0 N among the three cultivars. No significant differences were found between the fruit or stem dimensions and the force required for fruit removal. A stem-cutting end-effector prototype was then developed to conduct fruit removal experiments in field conditions. Two end-effector prototype configurations were tested: one placing the end-effector on a handheld bar, and the other integrating the end-effector with a six DoF robotic manipulator. The success rates of green fruit removal for all end-effector prototype experiments were over 90%. The end-effector is a core component of an automated green fruit thinning system. Integration with the robotic manipulator also indicated the potential of a robotic green fruit system to remove fruit at different locations and orientations. A machine vision system will be developed and integrated with the end-effector to develop a robotic green fruit thinning system. Keywords: Apple, Crop load management, End-effector, Fruit removal dynamics, Robotic thinning.

Plant origin and fruit traits shape fruit removal patterns by native birds in invaded plant communities

Biotic interactions and mutualisms in particular have an important role in ecosystem structure and functioning as well as in the maintenance of biodiversity. Understanding how communities respond to the introduction of non-native species and what determines the establishment of novel interactions between native and introduced species will help in determining the potential impacts of biological invasions. The aims of this work were to assess patterns of frugivory and fruit removal in environments with invasion of non-native fleshy-fruited plants and to evaluate whether novel associations between native frugivores and non-native plants are determined by fruit traits. For this we selected eight study sites in areas with different degrees of invasion of non-native fleshy-fruited plants. In each site, we measured fruit availability and fruit traits of native and non-native plants. In addition, we conducted direct frugivory observations. We found that native and non-native fruits differed based on morphological trait variables, such as fruit weight and dimensions. Only two birds, Elaenia albiceps (smaller and migrant) and Turdus falcklandii (bigger and resident), are the main frugivorous present in the area. At the scale of the community of frugivores, neither visit nor fruit removal rates differ between natives and non-natives. However, at the species scale, while E. albiceps preferentially foraged on native plants, T. falcklandii preferred non-natives. Thus, some generalist frugivorous species like T. falcklandii can play a key role in promoting the invasion of non-native plants.

Differences in the fruit removal patterns of Cleyera japonica by frugivorous birds in two forest stands at different developmental stages in a warm‐temperate region

AbstractWe investigated the fruit removal patterns of Cleyera japonica by frugivorous birds in two adjacent forest stands at different developmental stages due to secondary succession (a secondary deciduous forest stand, and an evergreen forest stand where evergreen oak is the dominant species) in a warm‐temperate region in western Japan. The fruit removal rate was significantly higher in the evergreen forest stand than in the deciduous forest stand, whereas the abundance of C. japonica fruits and that of all fleshy‐fruited woody species did not positively affect the fruit removal. However, the Cox proportional‐hazards model with mixed effects, using data concerning the disappearing patterns of mature fruits from twigs, implied that the fruit removal of C. japonica by birds within the crown was not significantly different from that between the stands. The timing of seed dispersal of C. japonica was prolonged in the evergreen forest stand compared with that in the deciduous forest stand. In the evergreen forest stand, considerable numbers of seeds were found in seed traps after early January, when almost all the fruits had disappeared from the crown. In the evergreen forest stand, we constantly observed gulpers that are assumed to forage C. japonica fruits frequently on the ground. These results suggested that the differences in the structural attributes between the forest stands influence the bird assemblage and their foraging patterns, which would lead to changes in the fruit removal patterns of C. japonica with the shift of forest stands due to secondary succession.

Effects of habitat fragmentation on frugivorous birds and on seed removal from Pistacia lentiscus in two contrasting fruiting seasons

Successful animal seed dispersal is the result of the interaction between frugivore behavior and the distribution of food resources, which can vary over space and time. We evaluated the interaction between avian frugivores and the masting shrub Pistacia lentiscus in both connected and isolated forest fragments along the Guadalquivir valley (south Iberian Peninsula) in two contrasting fruiting seasons (mast and non-mast). We compared the abundance and composition of avian dispersers and seed predators, recorded fruit removal rates by dispersers and predators, and investigated potential changes in the arrival of seeds to forest fragments. Our results showed that there was a greater abundance of dispersers in connected than in isolated fragments in the mast season (i.e. high fruit availability) but the opposite pattern in the non-mast season (i.e. low fruit availability). The effects of habitat fragmentation were more noticeable on medium-sized than small bird dispersers. Medium-sized birds were more abundant in isolated forest fragments but their abundance was highly dependent on the season, while small bird dispersers were apparently unaffected by fragmentation. Seed removal rates were higher in isolated than in connected fragments in the mast season but not in the non-mast season; predation rates were negligible in both seasons. Seed arrival was consistent between seasons and microhabitat where the dispersed seeds were deposited, most seeds being dispersed under the canopy of female Pistacia plants. We highlight the influence of the interplay between seasonality and landscape configuration on patterns of frugivore-mediated seed dispersal. Thus, despite its direct link to plant–frugivore interaction, the effects of habitat fragmentation on frugivores and plants were decoupled in our study system. These decoupled responses seemed to be chiefly due to the high feeding dependence of dispersers on P. lentiscus fruits.

Urbanization increases seed dispersal interaction diversity but decreases dispersal success in Toxicodendron radicans

Urbanization is increasing at a rapid pace with negative consequences for native biodiversity. While it is well-known that urbanization can lead to biotic homogenization (dominance of a few competitive species), effects of urbanization on ecological functions that rely on the frequency and efficiency of species interactions are less understood. Seed dispersal success depends on seed disperser feeding rate and diversity, which can affect the probability of fruit removal (i.e. seed dispersal) and germination rates. However, how these factors are affected by urbanization is unknown. In this study, we evaluate the effects of urbanization on factors that contribute to seed dispersal success (seed disperser diversity, frequency, probability of fruit removal and germination rate using Toxicodendron radicans and its seed disperser community as a model system. We found that urban sites had three times more disperser species and two times higher feeding rate compared to natural sites. However, the probability of individual fruit removal did not differ between natural and urban sites. Moreover, germination rate after dispersal was 20% lower in urban sites, leading to overall negative effects of urbanization on T. radicans seed dispersal. We propose differences in seed germination rate are driven by changes in seed disperser species composition and their differences in seed gut transit time. This in turn affects disperser species’ ability to successfully scarify seeds. Overall, our results highlight the need to evaluate urbanization’s effects on functional ecological processes, in addition to biotic homogenization effects, in order better understand and mitigate its negative impacts on biodiversity.

Evaluation of Shake-and-Catch Methods on Harvesting of Tall Spindle Apples

HighlightsBoth frequency and amplitude were influencing factors in analyzing the fruit removal efficiency and fruit damage.This research focused on tall spindle ‘Fuji’ apple trees, which enriched the study of the variety and architecture resources of apple trees.The advice for shake-and-catch harvesting was based on the analysis of amplitude and frequency from the perspective of energy consumption.Abstract. Almost all fresh-market apples are picked manually, and these apples rank among the most labor-intensive fruit crops to produce. Due to declining labor supply and rising labor costs, fresh-market apple growers are seeking mechanical harvesting solutions. Shake-and-catch is a potential method that has been well studied. However, because of fruit damage, this method cannot be widely used for fresh-market apples. The primary goal of this study was to investigate how the physical properties of the fruit tree and the shaker parameters affect fruit removal efficiency and fruit damage in an effort to help growers find solutions to the above-mentioned issues. A test system was developed, and its performance was evaluated in certain shaking modes. Based on the experimental results, the physical properties of the tree (length and diameter of limb, length and diameter of twig, and apple weight) and the frequency and amplitude of the shaker influenced the effectiveness of fruit detachment. When the amplitude of the shaker was 14.3 mm and the frequency was less than 15 Hz, the length of the twig had the greatest effect on fruit harvesting. However, with increasing frequency and amplitude, the effect of tree properties on fruit harvesting declined, and amplitude had a more significant effect on fruit harvesting than frequency. Moreover, the fruit removal rate reached 91.43% when the amplitude was 14.3 mm and the frequency was 20 Hz. The results of this study contribute to the development of an effective mechanical harvester that is adapted to tall spindle apple trees. Keywords: Amplitude, Apple fresh market, Frequency, Physical properties, Shake-and-catch, Tall spindle.

Interspecific competition for frugivores: population-level seed dispersal in contrasting fruiting communities.

Indirect interactions among plant species mediated by frugivorous animals can be central to population and community dynamics, since the successful seed dispersal of species may depend on facilitative or competitive interactions with heterospecific plants. Yet, empirical evidence on these interactions is very scarce and mostly available at small spatial scales, within populations. Because lipid-rich fruits are known to be preferred by migratory birds, here we test our prediction of competitive inferiority of a carbohydrate-rich fruited species (the hawthorn Crataegus monogyna) compared to lipid-rich co-fruiting species in a Mediterranean region where the bulk of seed dispersal relies on migratory birds. We assessed avian seed dispersal in both relative (fruit removal rate) and absolute terms (seed dispersal magnitude) in seven hawthorn populations distributed across an altitudinal gradient encompassing three contrasting fruiting contexts: hawthorn is scarce in the lowlands, common in the midlands, and the dominant fruit species in the highlands. We found evidence of seed dispersal reduction due to interspecific competition in the lowland populations, where lipid-rich fruits dominate. Besides, DNA barcoding analysis of bird-dispersed seeds revealed that only a small subset of the local frugivore assemblages consumed hawthorn fruits in the lowland communities. Instead, the consumers of hawthorn fruits resembled the local frugivore assemblages where hawthorn fruits were more dominant and frugivore choices more limited. Our study suggests mechanisms by which the rarity or dominance of plant species might be jointly influenced by environmental constraints (here, precipitation along the altitudinal gradient) and frugivore-mediated indirect interactions among plants hindering or facilitating seed dispersal.

Detecting plant spatial pattern change after disperser loss: A simulation and a case study

AbstractDisruption of seed dispersal processes may affect plant population spatial structure. We used a spatial simulation model and an empirical case study to assess the conditions under which the loss of seed dispersers has a detectable effect on a species' spatial pattern. Our simulation experiments suggested that detecting spatial change following disperser loss will be difficult, except when rates of fruit removal are initially high and then completely disappear. To contextualize the simulation modeling, we used spatial point pattern analyses to characterize the spatial pattern of two large‐seeded species (Leucopogon nutans, a fire‐killed seeder shrub and Macrozamia riedlei, a long‐lived, resprouting cycad) in the jarrah (Eucalyptus marginata) forests of southwestern Australia. The plant species' primary disperser, the emu (Dromaius novaehollandiae), was absent from one of the sites we considered, but present at the other two. There was no detectable difference for either plant species in the strength of aggregation between sites with and without emu. However, even if disperser loss may not greatly affect local spatial structure for most plant species, it is likely to be important for long distance dispersal and genetic structuring of populations, so accurate characterization of the dispersal kernel is critical, especially in terms of plant emigration.

Effects of temporal variation in community-level fruit abundance on seed dispersal by birds across woody species.

In animal-dispersed plants, seed dispersal patterns of the same species in the same habitat can greatly differ among individuals and temporally. Many studies have revealed the pervasive effects of spatial variation in fruit abundance on seed dispersal of individual plants. By contrast, very few studies have investigated the temporal variation in seed dispersal. We investigated the effects of conspecific and community-level fruit abundance on fruit removal rate and seed dispersal distance of six bird-dispersed woody species in a Japanese temperate forest for 3 yr. The six species share similar fruit characteristics but have different fruiting seasons. In addition, we also considered the effects of bird seasonality in diet and species composition on seed dispersal. Inter-annual and inter-seasonal variation in community-level fruit abundance determined both fruit removal and the seed dispersal distance across species, but the effect differed with seasonal changes in bird behavior. Abundant fruit satiated fruit removal by birds only during fruit-feeding periods, not during insect-feeding periods. A scarcity of fruit increased the dispersal distance, but only during the migratory period. This difference was probably due to the different foraging behaviors of passing migrants and territorial birds. Our results illustrated that temporal variation in community-level fruit abundance could be a determining factor for seed dispersal in temperate forests. The effects of temporal variations in fruit abundance on seed dispersal patterns should be investigated in other ecosystems in order to understand their importance and associations with frugivore phenology.

Intraspecific variation in fruit-frugivore interactions: effects of fruiting neighborhood and consequences for seed dispersal.

The extent of specialization/generalization continuum in fruit-frugivore interactions at the individual level remains poorly explored. Here, we investigated the interactions between the Neotropical treelet Miconia irwinii (Melastomataceae) and its avian seed dispersers in Brazilian campo rupestre. We built an individual-based network to derive plant degree of interaction specialization regarding disperser species. Then, we explored how intraspecific variation in interaction niche breadth relates to fruit availability on individual plants in varying densities of fruiting conspecific neighbors, and how these factors affect the quantity of viable seeds dispersed. We predicted broader interaction niche breadths for individuals with larger fruit crops in denser fruiting neighborhoods. The downscaled network included nine bird species and 15 plants, which varied nearly five-fold in their degree of interaction specialization. We found positive effects of crop size on visitation and fruit removal rates, but not on degree of interaction specialization. Conversely, we found that an increase in the density of conspecific fruiting neighbors both increased visitation rate and reduced plant degree of interaction specialization. We suggest that tracking fruit-rich patches by avian frugivore species is the main driver of density-dependent intraspecific variation in plants' interaction niche breadth. Our study shed some light on the overlooked fitness consequences of intraspecific variation in interaction niches by showing that individuals along the specialization/generalization continuum may have their seed dispersed with similar effectiveness. Our study exemplifies how individual-based networks linking plants to frugivore species that differ in their seed dispersal effectiveness can advance our understanding of intraspecific variation in the outcomes of fruit-frugivore interactions.

Differentiation of Fruiting Phenology and Seed Dispersal of Arisaema (Araceae) in Japan: The Effect of Fruiting Season on the Rates of Fruit Removal by Avian Frugivores

Differentiation of Fruiting Phenology and Seed Dispersal of <i>Arisaema</i> (<i>Araceae</i>) in Japan: The Effect of Fruiting Season on the Rates of Fruit Removal by Avian Frugivores