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Land‐use changes and habitat fragmentation can alter biodiversity and associated ecosystem functions.We investigated whether cropland expansion in south‐east Amazonia decreases ecosystem functions performed by ants and dung beetles by altering their communities.We sampled both groups in two forest types, in south‐eastern Amazonia: undisturbed riparian forests and riparian forests surrounded by croplands. We sampled ants and dung beetles with epigaeic pitfall traps, and experimentally assessed seed removal and predation by ants, and faeces and seed removal by dung beetles.Although ant and dung beetle abundance and richness did not differ across riparian forests, species composition of both groups did. Ants found seeds faster in undisturbed riparian forests, but the proportion of seed removal did not differ between forests. The abundance of predatory ants and the predation of termites by ants did not differ between forests.Seed and dung removal by dung beetles did not differ across riparian forests. Despite the observed differences in dung beetle composition, we did not find the effects on ecosystem functions probably due a functional redundancy of species.The quality of ecosystem functions provided by ants is lower in riparian forests surrounded by croplands, while changes in dung beetle diversity did not impact their ecosystem functions, with potential effects on the natural recovery of these disturbed riparian forests. [ABSTRACT FROM AUTHOR]

Seed predation may reduce the quantity and diversity of seeds and limit seedling recruitment. However, the extent to which seed predation may depend on the species and vegetational microhabitat has been less studied. We studied seed predation of woody species in the Mediterranean-type ecosystem of central Chile. We explored if interspecific differences in the magnitude of seed predation depends on the seed mass, evaluated the role vertebrate herbivores in seed predation, and examined if seed predation depends on the vegetation patch type. We conducted a seed removal experiment with eight woody species in three vegetation patch types (forest, shrub, and open) and replicated in two localities. We established exclosures for birds and mammals (wire cages covering 1 m2) and evaluated seed removal during 18 days within and outside of them. We also evaluated the soil seed availability by collecting soil samples inside and outside these exclosures after 2 years of exclusion in the same vegetation patches, adding other three localities. Exclosures significantly reduced the number of seeds removed in all species and patch types of both localities (overall 24.02% of removal in non-exclusion areas vs. 1.77% in exclosures). The magnitude of seed predation was negatively related to the seed mass of species. Exclosures significantly increased the number and species richness of seeds in the soil of forest and shrub patches of four localities. The results suggest that seed predation is mainly produced by vertebrates, affects several woody species from central Chile, and is more common in forest and shrub patches. [ABSTRACT FROM AUTHOR]

Ants and other insects are often a source of localized secondary dispersal for wind‐dispersed plants and thus play an important ecological role in their spatial dynamics, but there is limited information on how climate change will affect such dispersal processes. Here, we use field experiments to investigate how climate warming affects seed removal, as this initiation of movement represents the first step in insect‐driven secondary dispersal. Our results indicate that for the invasive thistles Carduus nutans and Carduus acanthoides, increased growing temperature influences seed attractiveness to insect dispersers, with seeds from maternal plants grown at temperatures 0.6°C above ambient removed by insect dispersers at higher rates than their unwarmed counterparts. We also observe that seed elaiosomes in these two species play an important role in dispersal, as seeds without elaiosomes were significantly less likely to be removed over the same period. Significant interactions between elaiosome presence/absence and warming treatment were also observed, though only for C. acanthoides, with the boost in seed removal from warming dampened when the elaiosome was present compared to when it was absent. These findings provide evidence that climate warming may alter aspects of dispersal such as seed removal by secondary dispersers, with potential ramifications for dispersal in future climates since seed‐bearing plants around the world may be subject to increased growing temperatures, and many of these plant species bear elaiosomes and experience seed dispersal by insects. [ABSTRACT FROM AUTHOR]

Seed dispersal influences the survival and distribution of plant species and is an important mechanism for maintaining floristic diversity. Bushpigs (Potamochoerus larvatus) are large mammals of indigenous forests and well-wooded areas of eastern and southern Africa and may play an important role as seed dispersers. However, the diversity of fruits consumed and the effect of digestion on seeds remains poorly understood. This study was conducted from October 2018 to January 2019 and gives first insights into seed dispersal by bushpigs in the Soutpansberg Mountain range, South Africa. Here, we collected bushpig faeces and assessed the number of seeds and seed species found. Furthermore, germination experiments with digested and nondigested seeds and fruits were conducted. Our results show that bushpigs are omnivorous, consuming fruits and seeds of 126 different plant species. The proportion of seeds per plant species found in faeces was unhomogeneously distributed with a few hyperabundant species, in particular Searsia chirindensis (55%). The germination experiments showed that gut passage did, overall, not influence germination or seedling growth rates. However, seeds remaining within fruits showed reduced growth, pointing to a high importance of fruit consumption for seed fate. Our results suggest that bushpigs are major seed dispersers of a large variety of fruiting plant species in wooded areas of Africa. [ABSTRACT FROM AUTHOR]

Objective: In order to solve the problem of poor integrity with mechanical coring and get the lantern pulp, and explore the factors affecting the performance of longan coring. Methods: Taking Guangdong 'Chuliang' longan fresh fruit as the research object, the key parts of core removal were designed and the core removal test platform was built. The core removal method with the ejector pin and flexible washer positioning was adopted. The ejector diameter, the rubber washer bore diameter and the ejector speed were chosen as the three main factors,and the stoning success rate, the stoning loss rate and the pulp integrity coefficient were chosen as the evaluation indicators. The single factor and orthogonal experiments were designed. Results: The experiments showed that the ranking of influence was rubber washer aperture ＞ ejector diameter ＞ ejector speed. When the ejector diameter was 7 mm, the rubber washer bore diameter was 14 mm and the ejector speed was 400 mm/min, the best stoning effect was got. Conclusion: It is feasible to obtain longan lantern pulp by the ejector rod mechanical enucleation method positioned with flexible washer and appropriate enucleation operation parameters.

In degraded drylands, direct sowing is one of the most widespread revegetation practices, but its efficiency is low and usually seed enhancement techniques are needed to increase its success. We evaluated how to induce seed dispersal by ants (myrmecochory), as this interaction could improve the chances of seed germination and seedling establishment, via seed transport to ants' nests where seeds are protected and the soils enriched. Our objective was to develop seeds with the addition of baits attractive to ants without affecting seed germination. First, we tested the attractiveness of baits of different sizes and ingredients by performing cafeteria experiments in nests of the omnivorous ant Dorymyrmex tener, the most abundant and effective seed disperser ant in the Patagonian steppe. Then, we attached the most preferred baits (small baits containing pate, sugar and clay) to seeds of two native plants species (Acaenasplendens and Oenothera odorata) with relevant characteristics for restoration purposes and tested their attractiveness to ants. We used different strategies to attach the bait to the seeds (e.g. encrusted, agglomerate and seeds on the surface) looking for the most attractive and simplest one. We found that only baited seeds were removed and the interaction was induced regardless of the way the bait was attached. Also, germination of seeds with bait was similar to that of seeds without bait in O. odorata, but reduced in A. splendens. We showed that it is possible to encourage ants to transport previously non‐attractive seeds through the design of baits, potentially improving direct sowing efficiency. [ABSTRACT FROM AUTHOR]

Secondary diaspore removal on the ground is an important ecosystem process. In this process, solitary foraging ants with larger body sizes are more efficient because they may remove more diaspores, faster and carry them at greater distances. Therefore, we sought to test the effects of the sizes of the morphological traits of ants, removal strategy, and nest distance on secondary diaspore removal, testing hypotheses related to the efficiency of this process. We evaluated the removal of artificial diaspores by ants in 15 areas of Cerrado sensu stricto (tropical savanna), collecting data on diaspore removal strategy (solitary or group), nest distance, diaspore discovery time, diaspore removal time, and the number of diaspores removed. Larger ants tended to remove diaspores alone and remove diaspores faster than smaller ones. Ants that removed diaspores alone removed more diaspores than ants that removed diaspores in groups. However, we did not find a linear relationship between ant size and diaspore removal. This is likely due to a limitation on, or a preference by larger ants for removing larger diaspores, while the smaller diaspores may have hindered manipulation or been less attractive to larger ants. Thus, the removal strategy was the best predictor of efficient diaspore removal performance, where the solitary foraging ants discover and remove diaspores quickly and remove more diaspores, mainly from the closest nests to the sampling point. However, the benefits (or not) of removing more diaspores still need to be evaluated.

Seed predation by rodents can strongly influence plant recruitment and establishment. The extent to which predation risk indirectly alters plant survival in tropical forests via impacts on granivory is unclear, making it difficult to assess the cascading impacts of widespread predator loss on tree recruitment and species composition. Experimental field studies that manipulate predation risk can help address these knowledge gaps and reveal whether antipredator responses among small mammals influence plant survival. We used camera traps and seed predation experiments to test the effects of perceived predation risk (via predator urine gel) on foraging behaviour of and seed removal by murid rodents in an unlogged and unhunted rainforest in Malaysian Borneo. We also explored the influence of seed traits (e.g., seed size) on removal by granivores and assessed whether granivore preferences for particular species were affected by predator urine. Murid visits to seed plots were positively related to overall seed removal, but were not affected by predator scent. Granivory was the lowest for the largest-seeded (>6 g) plant in our study, but was not influenced by predation risk. Predator urine significantly affected removal of one seed taxon (Dimoocarpus, ∼0.8 g), suggesting that removal by granivores may be affected by predation risk for some seed species but not others. This could have implications for plant species composition but may not affect the overall level of granivory. [ABSTRACT FROM AUTHOR]

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Abstract A better understanding of seed movement in plant community dynamics is needed, especially in light of disturbance‐driven changes and investments into restoring degraded plant communities. A primary agent of change within the sagebrush‐steppe is wildfire and invasion by non‐native forbs and grasses, primarily cheatgrass (Bromus tectorum). Our objectives were to quantify seed removal and evaluate ecological factors influencing seed removal within degraded sagebrush‐steppe by granivorous Owyhee harvester ants (Pogonomyrmex salinus Olsen). In 2014, we sampled 76 harvester ant nests across 11 plots spanning a gradient of cheatgrass invasion (40%–91% cover) in southwestern Idaho, United States. We presented seeds from four plant species commonly used in postfire restoration at 1.5 and 3.0 m from each nest to quantify seed removal. We evaluated seed selection for presented species, monthly removal, and whether biotic and abiotic factors (e.g., distance to nearest nest, temperature) influenced seed removal. Our top model indicated seed removal was positively correlated with nest height, an indicator of colony size. Distance to seeds and cheatgrass canopy cover reduced seed removal, likely due to increased search and handling time. Harvester ants were selective, removing Indian ricegrass (Achnatherum hymenoides) more than any other species presented. We suspect this was due to ease of seed handling and low weight variability. Nest density influenced monthly seed removal, as we estimated monthly removal of 1,890 seeds for 0.25 ha plots with 1 nest and 29,850 seeds for plots with 15 nests. Applying monthly seed removal to historical restoration treatments across the western United States showed harvester ants can greatly reduce seed availability at degraded sagebrush sites; for instance, fourwing saltbush (Atriplex canescens) seeds could be removed in

Abstract Seed removal by birds has been recognized as an important part of seed dispersal process in patchy forest areas; however, few studies have focused on the contribution of both plant and bird traits to seed removal. In this study, field data of seed removal for Taxus chinensis was combined with the data of bird and plant traits for analysis. The relevant traits of plants and birds that influenced T. chinensis–bird interaction were identified in a remnant patchy forest in yew ecological garden, Fujian Province, southeast China. Twenty bird species were found to forage and remove the seeds of T. chinensis. The number of bird species varied in different forest patches; however, their contribution to seed removal showed no significant differences. Both bird and plant traits were found to affect seed removal. The seed removal rate was positively affected by bird traits, such as foraging frequency and wing length, but decreased with body weight. The plant traits, such as number of fruits, tree height, canopy density, and crown width, which are related to safe shelter and food resource conditions, increased the seed removal rate. Our results underline the functional importance of bird and plant traits in the seed removal from endangered trees in patchy forests. Therefore, future conservation strategies should prioritize and recognize the role of both plant and bird traits in seed dispersal in remnant patchy forests.

Abstract Frugivorous birds vary in seed dispersal effectiveness (SDE) depending on their body mass. It has been suggested that large birds are more effective dispersers than small ones because they consume a large number of fruits, disperse seeds of distinct sizes, and transport seeds over long distances. Yet, few studies have evaluated the impact of body mass on SDE of birds. In this study, we compiled one database for the quantity (i.e., frequency of visits to plants and number of seeds removed per visit) and quality (i.e., germination of seeds after gut passage and gut retention time of seeds) of seed dispersal by frugivorous birds to evaluate the impact of body mass on SDE. In addition, we compiled data on plant characteristics such as life‐form, fruit type, number of seeds per fruit, and size of seed to evaluate their influence on the quantity and quality of seed dispersal. Data were analyzed with linear mixed effects models and quantile regressions to evaluate the relationship between body mass of birds and quantity, quality, and SDE, in addition to the influence of plant characteristics on SDE. The body mass of birds was negatively related to the frequency of visits to plants. Furthermore, it was positively related to the number of seeds removed per visit, although negatively related to seed size. The life‐form of plants was the only factor explaining the germination of seeds after gut passage. Yet, the body mass of birds was positively related to the gut retention time of seeds. Small and medium birds have a relatively higher SDE than large birds. These results differ from the assertion that large birds are more effective dispersers of plants. Small and medium birds are also effective dispersers of plants that should be preserved and protected from the impact of human activities.

Anthropogenic provisioning of food to wildlife is ubiquitous across the globe. It may be intentional such as in the form of bird feeders or offering of food to animals by tourists, or unintentional when animals use anthropogenic food sources like crops, plantations or garbage dumps. Provisioning has profound effects on wildlife ecology and behaviour, but the consequences of these changes to mutualistic and antagonistic interactions have rarely been investigated. Here we demonstrate how provisioning can affect the role of wildlife as seed dispersers. As provisioning directly influences the amount and quality of resources, it can substantially impact fruit removal by wildlife, seed displacement and the probability of germination at the sites of deposition – more often in ways that are detrimental. In most cases, fruit removal decreases as animals choose to feed more on the abundant and higher‐calorie anthropogenic foods. However, for animals whose size and abundance are increased by provisioning, dispersal quantity could be enhanced. Seed dispersal distances are also reduced by provisioning, and seeds are often deposited at sites unsuitable for germination. More studies are required to understand how these broad patterns might vary across different contexts and wildlife species. Provisioning has the potential to greatly modify plant communities through the direct impacts it has on resources and wildlife seed dispersal services. [ABSTRACT FROM AUTHOR]

Introduction: Seed removal by ants is an interaction that may greatly affect the dynamic and structure of the vegetation. This aspect is well known for granivorous ants; however, there is little information on the effect of omnivorous ants. Objective: To assess the potential impact of the omnivorous ant Dorymyrmex insanus on vegetation. Methods: In the Pedregal Reserve, Mexico City, we identified the items in the refuse piles of ten ant colonies, for one year, covering the rainy and dry seasons. For each season we calculated seed diversity and analyzed the possible relationship between seed size and their abundance in the refuse piles, with regression models. We also did germination tests with seeds of Tagetes micrantha, comparing seeds from piles and from plants. Results: D. insanus removed seeds of 19 plant species as well as plant remains (such as leaves, twigs, roots), and remains of insects. Seed diversity was higher in the rainy season but the greatest abundance was in the dry season. When analyzing the relationship between seed length and abundance in the refuse piles, we found that the ants preferred seeds of around 10 mm. We also found that more seeds of T. micrantha germinated when they were previously handled by ants. Conclusions: The ant D. insanus actively participates in the removal of seeds from several species, favoring germination, and seasonality affects the selectivity of resources. [ABSTRACT FROM AUTHOR]

Ants are able to interact with fruits and seeds that are not adapted for ant seed dispersal. In Brazil, several studies show interactions of ants with non-myrmecochorous diaspores; however, few of them have studied the structure of ant-fruit networks. The use of the network approach allows visualising multiple interactions between partners and how they are shaped by the community context. Our study aims to investigate ant-fruit networks as well as quantitative and qualitative dispersal components in a fragment of the Brazilian Atlantic Forest. We investigated the structure of interaction networks, diaspore removal rates, diaspore destination and dispersal distance over two years of observation. We constructed three interaction networks: dry season, rainy season and total, with the latter comprising the two formers. The diaspore removal rate, dispersal distance and diaspore destination experiments were performed for the plant species Miconia calvescens, Miconia prasina, Psychotria leiocarpa and Inga edulis. We recorded a large number of interactions, with diaspore cleaning being more frequent than removal. Ant-diaspore networks were nested, non-modular and little specialized. M. calvescens, M. prasina and I. edulis showed higher diaspore removal rates. Diaspore removal distances were the same among M. calvescens, M. prasina and I. edulis. In M. calvescens and I. edulis, the main diaspore destination was the ant’s nest. Our study shows that diaspore cleaning is the most common behavior in ant-diaspore interactions and there are no differences in the organization of interaction networks over the seasons. These results have implications for the future structure of plant communities, considering that a small part of the diaspores is removed, and that most of them are cleaned, favouring germination at the deposition site.

Mutualistic interactions form the basis for many ecological processes and are often analyzed within the framework of ecological networks. These interactions can be sampled with a range of methods and first analyses of pollination networks sampled with different methods showed differences in common network metrics. However, it is yet unknown if metrics of seed dispersal networks are similarly affected by the sampling method and if different methods detect a complementary set of frugivores. This is necessary to better understand the (dis‐)advantages of each method and to identify the role of each frugivore for the seed dispersal process. Here, we compare seed removal networks based on the observation of 2189 frugivore visits on ten focal plant species with seed deposition networks constructed by DNA barcoding of plant seeds in 3094 frugivore scats. We were interested in whether both methods identify the same disperser species and if species‐level network metrics of plant species were correlated between network types. Both methods identified the same avian super‐generalist frugivores, which accounted for the highest number of dispersed seeds. However, only with DNA barcoding, we detected elusive but frequent mammalian seed dispersers. The overall networks created by both methods were congruent but the plant species' degree, their interaction frequency and their specialization index (d′) differed. Our study suggests that DNA barcoding of defecated and regurgitated seeds can be used to construct quantitative seed deposition networks similar to those constructed by focal observations. To improve the overall completeness of seed dispersal networks it might be useful to combine both methods to detect interactions by both birds and mammals. Most importantly, the DNA barcoding method provides information on the post‐dispersal stage and thus on the qualitative contribution of each frugivore for the plant community thereby linking species interactions to regeneration dynamics of fleshy‐fruited plant species. [ABSTRACT FROM AUTHOR]

It has been hypothesized that biotic interactions are stronger towards lower latitudes and elevations. However, results vary among interaction systems and experimental protocols. Our goal was to examine the validity of this prediction by using a standardized method to investigate seed–animal interaction. We assessed removal by animals for 40 960 seeds belonging to 32 non‐native tree species along an elevation gradient from 600 m to 2910 m on Mount Victoria (Nat Ma Taung), western Myanmar. We analyzed the elevational trends of seed removal at both individual seed level (probability of depot encounter, proportion of seeds removed after encounter and total proportion of seeds removed) and community level (Shannon diversity and species evenness indices). The dry and wet seasons had opposite relationships between seed removal and elevation, i.e. hump‐shaped in the dry season and U‐shaped in the wet season. Individual plant species displayed almost all possible patterns: U‐shaped and hump‐shaped, monotonic decrease and increase, and elevation‐independent patterns. As a consequence of the hump‐shaped seed removal pattern with elevation in the dry season, the diversity and evenness of surviving seeds showed U‐shaped patterns. Our study shows that elevational trends in seed–animal interactions do not follow a constant rule, but differ between seasons and among species, suggesting that a one‐off survey with few species might give misleading information on overall macroecological patterns. Future studies of trends in biotic interactions along gradients should bear this in mind. [ABSTRACT FROM AUTHOR]

Decomposition, vegetation regeneration, and biological control are essential ecosystem functions, and animals are involved in the underlying processes, such as dung removal, seed removal, herbivory, and predation. Despite evidence for declines of animal diversity and abundance due to climate change and land-use intensification, we poorly understand how animal-mediated processes respond to these global change drivers. We experimentally measured rates of four ecosystem processes in 134 grassland and 149 forest plots in Germany and tested their response to climatic conditions and land-use intensity, that is, grazing, mowing, and fertilization in grasslands and the proportion of harvested wood, non-natural trees, and deadwood origin in forests. For both climate and land use, we distinguished between short-term effects during the survey period and medium-term effects during the preceding years. Forests had significantly higher process rates than grasslands. In grasslands, the climatic effects on the process rates were similar or stronger than land-use effects, except for predation; land-use intensity negatively affected several process rates. In forests, the land-use effects were more pronounced than the climatic effects on all processes except for predation. The proportion of non-natural trees had the greatest impact on the process rates in forests. The proportion of harvested wood had negative effects, whereas the proportion of anthropogenic deadwood had positive effects on some processes. The effects of climatic conditions and land-use intensity on process rates mirror climatic and habitat effects on animal abundance, activity, and resource quality. Our study demonstrates that land-use changes and interventions affecting climatic conditions will have substantial impacts on animal-mediated ecosystem processes. [ABSTRACT FROM AUTHOR]

Seed removal behaviors of rodents are largely influenced by microhabitat. Although the karst ecosystem is composed of a broad variety of microhabitats, we have no information on how they affect such behaviors. We investigated rodents’ seed removal behaviors in four karst microhabitats (stone cavern, stone groove, stone surface, and soil surface) using three types of Kmeria septentrionalis seeds: fresh, black (intact seeds with black aril that dehydrates and darkens), and exposed (clean seeds without the aril). We show that Rattus norvegicus, Leopoldamys edwardsi and Rattus flavipectus were the predominant seed predators. Even though all seed types experienced a high removal rate in all four microhabitats, but rodents preferentially removed seeds from the three stone microhabitats (stone caves: 69.71 ± 2.74%; stone surface: 60.53 ± 2.90%; stone groove: 56.94 ± 2.91%) compared to the soil surface (53.90 ± 2.92%). Seeds that had been altered by being exposed to the environment were more attractive to rodents than fresh seeds (76.25 ± 2.20% versus 36.18 ± 2.29%). The seed removal behavior of rodents was significantly affected by the microhabitat and seed type. Finally, seeds that had fallen on the soil surface microhabitat incurred a lower predation risk than seeds fallen on other microhabitats, which increased their probability to germinate. Our results indicate that the lower predation rate of seeds from the endangered K. septentrionalis dropped on the soil surface increases trees’ likelihood of survival.

Granivore ant foraging should respond to seed density through changes in individual and collective behaviour. Overall seed availability and the presence of multiple types of seeds in a patch may affect these behaviours. We presented ants with three species of seeds in different mixtures and in two seasons contrasting in seed availability to assess differences in probabilities of seed collection. Removal rates were recorded every 2 h. We fitted a model that uses data on seed removal to disentangle the individual (probability that an ant removes a seed of species i, pi) and collective (number of active ants h) components of foraging. We found that removal increased with seed density due to increased pi values and recruitment of new ants. This suggests that ants evaluated resource density, collecting seeds only from dense patches. This was confirmed by observations. The presence of additional seeds of other species in the seed mixture elicited recruitment but had nearly no effect on pi. This may be observed if different ants prefer a seed species and ignore the rest. In the low seed-availability season, h increased, ants travelled longer distances, and foraging was directed to the most profitable seed-patches. This selectivity for some seed-patches during times of scarcity may appear surprising. It is true that, by abandoning low-density patches, individuals may reduce their seed acquisition rates, but also increase collective gains by forming trails only to dense patches. This may compensate for the large collective investments in the form of more scouts that explore longer distances. [ABSTRACT FROM AUTHOR]

Seed dispersal and predation are paramount for tropical plant diversity. When encountered by scatter-hoarding frugivores, seeds can be either eaten, dispersed or ignored. But even after dispersal, seed caches are still subjected to predation. Many factors are known to influence these dynamics; however, how frequently hoarders use certain patches has seldom been related to cache predation rates. We used the interaction between agoutis (Dasyprocta leporina), a scatter-hoarding rodent, and Joannesia princeps, a tropical tree, as a model to investigate how the number of visits by hoarders in certain areas influences cache predation and seed fate. Camera-traps were used for 30 days in twenty different locations in Tijuca National Park to assess number of visits by agoutis. Thereafter, we placed seed piles on the same areas and determined their fate using the spool-and-line method to track seeds for over one hundred days. We found a non-linear relationship between how often an area is used by hoarders and the final proportion of dispersed seeds. At areas with a low number of visits, proportion of dispersed seeds was low due to low removal. As frequency of visits by hoarders increased, seed removal and the number of dispersal events increased but so did cache predation. Thus, in areas intensively used by hoarders, high cache predation resulted in a low number of dispersed seeds that remained alive in caches. As a result, dispersal was maximized in areas with intermediate use by scatter-hoarders, where there was a balance between primary seed dispersal and cache predation. [ABSTRACT FROM AUTHOR]

A better understanding of seed movement in plant community dynamics is needed, especially in light of disturbance‐driven changes and investments into restoring degraded plant communities. A primary agent of change within the sagebrush‐steppe is wildfire and invasion by non‐native forbs and grasses, primarily cheatgrass (Bromus tectorum). Our objectives were to quantify seed removal and evaluate ecological factors influencing seed removal within degraded sagebrush‐steppe by granivorous Owyhee harvester ants (Pogonomyrmex salinus Olsen). In 2014, we sampled 76 harvester ant nests across 11 plots spanning a gradient of cheatgrass invasion (40%–91% cover) in southwestern Idaho, United States. We presented seeds from four plant species commonly used in postfire restoration at 1.5 and 3.0 m from each nest to quantify seed removal. We evaluated seed selection for presented species, monthly removal, and whether biotic and abiotic factors (e.g., distance to nearest nest, temperature) influenced seed removal. Our top model indicated seed removal was positively correlated with nest height, an indicator of colony size. Distance to seeds and cheatgrass canopy cover reduced seed removal, likely due to increased search and handling time. Harvester ants were selective, removing Indian ricegrass (Achnatherum hymenoides) more than any other species presented. We suspect this was due to ease of seed handling and low weight variability. Nest density influenced monthly seed removal, as we estimated monthly removal of 1,890 seeds for 0.25 ha plots with 1 nest and 29,850 seeds for plots with 15 nests. Applying monthly seed removal to historical restoration treatments across the western United States showed harvester ants can greatly reduce seed availability at degraded sagebrush sites; for instance, fourwing saltbush (Atriplex canescens) seeds could be removed in <2 months. Collectively, these results shed light on seed removal by harvester ants and emphasize their potential influence on postfire restoration within invaded sagebrush communities. [ABSTRACT FROM AUTHOR]

Frugivorous birds vary in seed dispersal effectiveness (SDE) depending on their body mass. It has been suggested that large birds are more effective dispersers than small ones because they consume a large number of fruits, disperse seeds of distinct sizes, and transport seeds over long distances. Yet, few studies have evaluated the impact of body mass on SDE of birds. In this study, we compiled one database for the quantity (i.e., frequency of visits to plants and number of seeds removed per visit) and quality (i.e., germination of seeds after gut passage and gut retention time of seeds) of seed dispersal by frugivorous birds to evaluate the impact of body mass on SDE. In addition, we compiled data on plant characteristics such as life‐form, fruit type, number of seeds per fruit, and size of seed to evaluate their influence on the quantity and quality of seed dispersal. Data were analyzed with linear mixed effects models and quantile regressions to evaluate the relationship between body mass of birds and quantity, quality, and SDE, in addition to the influence of plant characteristics on SDE. The body mass of birds was negatively related to the frequency of visits to plants. Furthermore, it was positively related to the number of seeds removed per visit, although negatively related to seed size. The life‐form of plants was the only factor explaining the germination of seeds after gut passage. Yet, the body mass of birds was positively related to the gut retention time of seeds. Small and medium birds have a relatively higher SDE than large birds. These results differ from the assertion that large birds are more effective dispersers of plants. Small and medium birds are also effective dispersers of plants that should be preserved and protected from the impact of human activities. [ABSTRACT FROM AUTHOR]

Tropical rain forests worldwide are under increasing pressure from human activities, which are altering key ecosystem processes such as plant–animal interactions. However, while the direct impact of anthropogenic disturbance on animal communities has been well studied, the consequences of such defaunation for mutualistic interactions such as seed dispersal remains chiefly understood at the plant species level. We asked whether communities of endozoochorous tree species had altered seed removal in forests affected by hunting and logging and if this could be related to modifications of the frugivore community. At two contrasting forest sites in French Guiana, Nouragues (protected) and Montagne de Kaw (hunted and partly logged), we focused on four families of animal‐dispersed trees (Sapotaceae, Myristicaceae, Burseraceae, and Fabaceae), which represent 88% of all endozoochorous trees that were fruiting at the time and location of the study. We assessed the abundance of the seed dispersers and predators of these four focal families by conducting diurnal distance sampling along line transects. Densities of several key seed dispersers such as large‐bodied primates were greatly reduced at Montagne de Kaw, where the specialist frugivore Ateles paniscus is probably extinct. In parallel, we estimated seed removal rates from fruit and seed counts conducted in 1‐m2 quadrats placed on the ground beneath fruiting trees. Seed removal rates dropped from 77% at Nouragues to 47 % at Montagne de Kaw, confirming that the loss of frugivores associated with human disturbance impacts seed removal at the community level. In contrast to Sapotaceae, whose seeds are dispersed by mammals only, weaker declines in seed removal for Burseraceae and Myristicaceae suggest that some compensation may occur for these bird‐ and mammal‐dispersed families, possibly because of the high abundance of Toucans at the disturbed site. The defaunation process currently occurring across many tropical forests could dramatically reduce the diversity of entire communities of animal‐dispersed trees through seed removal limitation. [ABSTRACT FROM AUTHOR]

Post‐dispersal seed predation plays an important role in plant demography and biodiversity maintenance. However, the effects of seed density on seed predation from previous studies have been inconsistent. We dissected the effects of density on the 2‐step processes of seed predation using 101 520 seeds from 62 plant species in an alpine pine forest for 3 consecutive years. In this study we explained the current controversy surrounding the effects of density on seed predation. Seed encounter frequency (at least 1 seed being predated from an experiment depot) showed positive density dependence, while seed exploitation (the proportion of seeds being predated of the encountered depots) showed negative density dependence. Both density effects showed a consistent trend but with different magnitudes of effect across years. Final seed predation is the combination of seed encounter and seed exploitation. Final seed predation could be either positively or negatively density‐dependent and was contingent on the magnitude of the difference between positive density‐dependent seed encounter and negative density‐dependent seed exploitation. Our results also indicated that studies including only a few species would produce biased results, because the density effect on seed predation differed greatly among plant species. Future studies should include a large number of plant species that possess a wide range of diverse seed traits to avoid potential bias and produce more comprehensive and accurate results. [ABSTRACT FROM AUTHOR]

Abstract 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 (Pycnonotidae) 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.

Seed sowing is a common early step in restoration, but seed consumers can impede plant establishment and alter community structure. Moreover, seed consumers vary in feeding behaviors and the relative importance of different seed consumer groups during restoration are not well understood. At 12 first‐year prairie restorations in Michigan, we studied seed predation using seed removal trays to ask: What is the relative magnitude of seed removal by insects and mammals? Do seed removal rates change over the growing season? Do habitat edges influence seed removal? At what rates are 10 prairie plant species' seeds removed by mammals and insects? Seed removal depended on consumer type, time of year, and seed species. Insects accounted for the majority of seed removal, contrary to previous research in similar systems. In May, insects removed 1.8 times more seeds than mammals, while in August, they removed 5.1 times more. There was greater seed removal in August. During May 28% of seeds were removed, compared to 54% of seeds removed during August, an increase driven by insects. Edge proximity did not influence seed removal. Certain seed species were removed more than others. For example, Lespedeza capitata (round‐headed bush clover) was always removed at high rates, whereas Coreopsis lanceolata (lance‐leaved coreopsis) and Andropogon gerardii (big bluestem) were always removed at low rates. Mammals and insects showed different preferences for several species. This research suggests a prominent role of seed predation, particularly by insects, for early prairie restoration dynamics, with influences varying temporally and among species. [ABSTRACT FROM AUTHOR]

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

High rates of seed removal can impede forest recovery, but tropical seed removal studies are few and mainly from the neotropics. Little is known about the comparative influences of active restoration (i.e. planting) and passive restoration (i.e. protection of natural regrowth) on seed removal. We conducted an evaluation of seed removal in grasslands, natural forests (tropical moist semideciduous forest), and actively (21‐, 17‐, 16‐, 11‐, 8‐, and 6‐year‐old) and passively (21‐year‐old) restored forests in Kibale National Park, Uganda. We wanted to compare the effect of vegetation type, time since restoration and restoration actions (i.e. active vs. passive) on removal of seeds of five animal‐dispersed tree species during wet and dry seasons. Seeds were either fully exposed or placed in closed mesh cages or under a mesh roof. We used differential removal rates between these treatments to attribute seed removal to different animal taxa. Seed removal rate (percentage of seed removed over a 4‐day period) was highest in passively restored forests, compared with actively restored forests, grasslands, and natural forests. We detected no significant relationship between time since restoration and seed removal rates within actively restored sites. Seed removal rate from roofed treatments was not significantly different from removal from open treatments but was significantly higher than removal from closed treatments, which we interpret as reflecting the greater effect of small mammals versus insects. Smaller seeds tended to be removed at a greater rate than larger seeds. We discuss the implications of these findings for forest regeneration. [ABSTRACT FROM AUTHOR]

Invasive alien plant species in a new location usually lose their native enemies, but new interactions with local herbivores can also significantly influence their population dynamics. Seed predators have a strong effect on the seed banks, seedling recruitment, and establishment of a plant population. A given plant’s effective defence of its seeds from seed predators ensures its survival. Here, we describe a new kind of physical protection in the wild cucumber (Echinocystis lobata) in its invasive range: the production, in the central part of the fruit’s fibre frame, of 1 or 2 additional seeds which cannot be released. Research was conducted in riparian habitats in the central part of Poland. After performing three different studies to examine this phenomenon, we found that, on average, 34% of individual wild cucumber fruits contained additional trapped seeds which could not be released. Our results showed that trapped seeds have the same ability to germinate as normally released seeds, but that they differ from normal seeds in weight and shape. The frequency of removal of trapped seeds by rodents was significantly lower than that of normally released seeds. This mechanism is likely to change seed distribution in the wild cucumber’s environment. [ABSTRACT FROM AUTHOR]

Abstract: Considerable areas dominated by bracken Pteridium aquilinum (L.) Kuhn occur worldwide and are associated with arrested forest recovery. How forest recovery is impeded in these areas remains poorly understood, especially in the African highlands. The component processes that can lead to recruitment limitation—including low seed arrival, availability and persistence—are important determinants of plant communities and offer a potential explanation for bracken persistence. We investigated key processes that can contribute to recruitment limitation in bracken‐dominated clearings in the Bwindi Impenetrable National Park, Uganda. We examined if differences in seed rain (dispersal limitation), soil seed bank, or seed removal (seed viability and persistence) can, individually or in combination, explain the differences in tree regeneration found between bracken‐dominated areas and the neighboring forest. These processes were assessed along ten 50‐m transects crossing the forest–bracken boundary. When compared to the neighboring forest, bracken clearings had fewer seedlings (bracken 11,557 ± 5482 vs. forest 34,515 ± 6066 seedlings/ha), lower seed rain (949 ± 582 vs. 1605 ± 335 tree seeds m−2 year−1), comparable but sparse soil seed bank (304 ± 236 vs. 264 ± 99 viable tree seeds/m2), higher seed removal (70.1% ± 2.4% vs. 40.6% ± 2.4% over a 3‐day interval), and markedly higher rodent densities (25.7 ± 5.4 vs. 5.0 ± 1.6 rodents per 100 trapping sessions). Camera traps revealed that rodents were the dominant animals visiting the seeds in our seed removal study. Synthesis: Recruitment limitation contributes to both the slow recovery of forest in bracken‐dominated areas, and to the composition of the tree species that occur. Low seed arrival and low persistence of unburied seeds can both explain the reduced density of seedlings found in bracken versus neighboring forest. Seed removal, likely due to rodents, in particular appears sufficient to constrain forest recovery and impacts some species more severely than others. [ABSTRACT FROM AUTHOR]

Seed removal can influence plant community dynamics, composition, and resulting vegetation characteristics. In the African savanna, termites and large herbivores influence vegetation in various ways, likely including indirect effects on seed predators and secondary dispersers. However, the intensity and variation of seed removal rates in African savannas has seldom been studied. We experimentally investigated whether termites and large herbivores were important factors in the mechanisms contributing to observed patterns in tree species composition on and off mounds, in Lake Mburo National Park, Uganda. Within fenced (excluding large herbivores) and unfenced termite mound and adjacent savanna plots, we placed seeds of nine native tree species within small open 'cages,' accessed by all animals, roofed cages that only allowed access to small vertebrates and invertebrates, and closed cages that permitted access by smaller invertebrates only (5 mm wire mesh). We found that mean seed removal rate was high (up to 87.3% per 3 d). Mound habitats experienced significantly higher removal rates than off-mound habitats. The mean removal rate of native seeds from closed cages was 11.1% per 3 d compared with 19.4% and 23.3% removed per 3 d in the roofed and open cages, respectively. Smaller seeds experienced higher removal rates than larger seeds. Large herbivore exclusion on mounds reduced native seed removal rates by a mean of 8.8% in the open cages, but increased removal rates by 1.7% in the open cages when off-mound habitats were fenced. While removal rates from open cages were higher on active mounds (30.9%) than on inactive mounds (26.7%), the removal rates from closed cages were lower on active vs. inactive mounds (6.1% vs. 11.6%, respectively). Thus, we conclude that large herbivores and Macrotermes mounds influence seed removal rates, though these effects appear indirect. [ABSTRACT FROM AUTHOR]

Aim Biotic interactions have traditionally been predicted to be stronger towards the tropics. However, all previous studies about the latitudinal gradient in seed predation were either based on single species or compiled data from studies that used different methods in different ecosystems. Our goal was to provide the first broad-scale quantification of the latitudinal gradient in seed predation at both cross-species and within-species levels. Location Twenty-five sites spanning 28° of latitude on the east coast of Australia. Methods Using consistent protocols, we measured pre-dispersal seed predation for 256 species × site combinations (including a total of 170 species) and post-dispersal seed removal for 126 species × site combinations (including a total of 91 species), as well as removal of standard rice grains at each site. The relationships between seed predation and latitude were quantified using generalized mixed-effects models and meta-analyses. Results Contrary to expectations, the proportion of seeds lost to pre-dispersal seed predation increased with latitude at the cross-species level and showed no latitudinal trend at the within-species level. There was no significant relationship between latitude and the proportion of seeds lost to post-dispersal seed removal, either within species or across species. We found significantly higher removal of standard rice grains at lower latitudes, but this trend reversed if we excluded the four island sites from analysis. Main conclusions Seed predation on natural seeds was not higher at lower latitudes. Thus, our study joins a growing body of evidence contrary to the idea that tropical species suffer greater losses to herbivores than do temperate species. The latitudinal gradient in removal rates for standard rice grains suggests that natural seeds from low latitudes may have achieved a similar predation rate to high-latitudinal species through increased investment in defenses. However, additional data will be necessary to test this hypothesis. [ABSTRACT FROM AUTHOR]

Tree species often exhibit considerable variability among individuals in seed crop size and averaged seed mass within the same year. However, very little is known about the consequences for seed consumers’ preferences of this potentially large between-individual variability. In this study we quantified seed production and seed manipulation rates by animals over three years in two coexisting oak species of southeast Mexico ( Quercus germana and Q. xalapensis ) with the principal aim of evaluating the influence of two relevant plant traits (individual crop size and seed mass) on the responses of two guilds of acorn consumers with contrasting foraging behaviors and dietary breadths (vertebrate versus granivorous insects). We detected interactive effects of these two plant traits on seed consumers’ preferences, with important differences between the two groups of acorn-feeding animals. In general, high densities of large-sized acorns triggered a negative density-dependent response (i.e. satiating effect) in granivorous insects and a positive response (i.e. attractive effect) in vertebrates, whereas the opposite occurred when considering the fraction of small-sized acorns. The potential consequences of producing bigger seeds will partly depend on the relative abundance of the two guilds of acorn consumers. Thus, in plant populations with overabundance of vertebrates, the higher attraction of large-sized seeds for these generalist consumers could counteract the satiating effect exercised on granivorous insects through multi-infestation. However, in forest sites with less abundance of vertebrates, the risk of seed predation (mostly by insects) could be reduced in those trees producing huge quantities of large-sized seeds. In summary, we found clear evidences that the direction and magnitude of density-dependent seed removal can differ not only between different groups of seed consumers but also among different fractions of seed size, which highlights the importance of considering this plant trait to better understand the complexity of mechanisms operating in these plant-animal interactions. [ABSTRACT FROM AUTHOR]

The assisted regeneration of oaks can be achieved through seeding or planting. Whereas direct seeding of acorns has several advantages over planting nursery-grown seedlings, the problem of seed predation by mammals precludes its widespread application. We investigated the potential of diesel as a mammal repellent to prevent the consumption of Holm oak acorns. We tested the effect of submerging acorns in diesel for 0, 6, 12, and 24 h on acorn predation in a field experiment in the Sierra Nevada Natural Park (Granada province, Spain), and the potential effect of the same treatments on seedling emergence and growth in a nursery experiment. The field experiment showed no reduction in acorn predation through diesel. On the other hand, submersion in diesel hindered the germination of one in every four sown acorns regardless of submersion time. Our results are in line with many failed attempts to protect acorns with chemical repellents and suggest that an effective, universally-abundant, inexpensive, and easy-to-apply acorn protector to enhance the success of seeding operations is yet to be found. [ABSTRACT FROM AUTHOR]