On the density-dependence of seed predation in<Emphasis Type="Italic"> Dipteryx micrantha</Emphasis>, a bat-dispersed rain forest tree

We studied the effect of seed density on seed predation by following the fate of bat-dispersed Dipteryx micrantha (Leguminosae) seeds deposited under bat feeding roosts. The study was conducted in Cocha Cashu biological station, Amazonian Peru, during the fruiting period of Dipteryx. Predation of Dipteryx seeds in the area is mainly by large to medium-sized rodents. Seed deposits beneath bat feeding roosts were monitored for a 13-week period in an 18-ha study area. A total of 210 seed deposits were found, and on average, seed predators encountered 22% of them during any one week. About one-third of the seed deposits escaped predation, and those deposits that had relatively few seeds were more likely to go unnoticed by rodents than were deposits with many seeds. The mean seed destruction rate was 8% per week; deposits with many seeds tended to lose a smaller proportion of their seeds to seed predators than did deposits with few seeds. Regression tests for the weekly data showed that, at the beginning of the observation period, seed predation was not density-dependent. Later, when the total seed crop beneath roosts was high, the number of seeds predated per deposit was positively density-dependent, while the proportion of seeds predated was negatively density-dependent, indicating predator satiation. Seed deposits that had been visited by seed predators once had a higher probability of being revisited the week after, especially if they contained many seeds when first encountered. This indicates that the foraging behavior of rodents may be affected by their remembering the location of seed-rich patches.     

Bimodal colour pattern of individual Pinus halepensis Mill. seeds: a new type of crypsis

Variation in seed traits is a well‐known phenomenon affecting plant ecology and evolution. Here we describe, for the first time, a bimodal colour pattern of individual seeds, proposing an adaptive explanation, using Pinus halepensis as a model. Pinus halepensis disperses its seeds either by wind on hot dry days, from regular cones, or after fires, mainly from serotinous cones. Post‐dispersal seeds are exposed to strong predation by passerine birds, making crypsis important for seed survival. Individual seeds from non‐serotinous cones have a bimodal colour pattern: one side is light brown and the other black, exposing only one colour when lying on the ground. Serotinous cones from most trees have seeds with similar bimodal colour patterns, whereas seeds from serotinous cones of some trees are light brown on both sides. The dark side provides the seed with better crypsis on dark soils, whereas the light‐brown side is better adapted to light‐coloured soils, and mainly to light‐grey ash‐covered soil, which is the natural post‐fire regeneration niche of P. halepensis. The relative reflection curves of the black and brown seed colours differ, and their calculated relative chromatic distance is 5: meaning that seed‐predating passerine birds see them differently, and probably prefer seeds that present a higher contrast against the soil background. We propose that such a bimodal colour pattern of individual seeds is probably an overlooked general phenomenon mainly linked to seed dispersal in post‐fire and other heterogeneous environments. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 271–278.     

Seed predation of two alien Opuntia species invading Mediterranean communities

Invasibility depends on the interaction of the introduced species with the abiotic and biotic factors of the recipient community. In particular, the biotic resistance posed by native herbivores has been claimed to be of great importance in controlling plant invasion. We investigated fruit and seed predation of two exotic Opuntia species within and between Mediterranean communities in order to determine how patterns of predation matched patterns of invasion. Predators were small mammals, presumably mice, which could consume more than 50% of the seeds produced. Predators could be equally effective in consuming fruit and single seeds. O. maxima fruits were slightly preferred to O. stricta fruits, but predators did not distinguish between seeds. Seed predation was more intense in invaded than in non-invaded communities. However, there was a high spatial variation in seed predation that did not always match patterns of invasion, suggesting that seed predation alone is not a good predictor of community invasibility to Opuntia. According to these results invasibility to Opuntia is limited in some (but not all) communities by native mice. Seed losses by predation were high for both species. However, we estimated that more than 75% of seeds dispersed by birds to non-invaded areas are not predated.     

Post‐dispersal seed predation and its relations with seed traits: a thirty‐species‐comparative study

Post‐dispersal seed predation is a key process determining the variability in seed survival in forests, where most seeds are handled by rodents. Seed predation is thought to affect seedling regeneration, colonization ability and spatial distribution of plants. Basic seed traits are the essential factors affecting rodent foraging preferences and thus seed survival and seedling recruitment. Many studies have discussed several seed traits and their effects upon seed predation by rodents. However, the results of those previous studies are usually equivocal, likely because few seed traits and/or plant species tend to be incorporated into these studies. In order to elucidate the relationships between seed predation and seed traits, we surveyed the predation of 48 600 seeds in a natural pine forest, belonging to 30 species, for three consecutive years. The results demonstrated that: (i) seed size and seed coat hardness did not significantly affect seed predation; (ii) total phenolics had a negative effect upon seed predation; (iii) positive effects of nitrogen content upon seed predation were found. From our study, it seems that the better strategy to prevent heavy predation is for plants to produce seeds with higher total phenolics content rather than physical defenses (i.e. hard seed coat) or larger seeds. Additionally, rodent foraging preference may depend more on Nitrogen content than other nutrient content of seeds.     

Effect of distance,aggregation, and habitat on levels of seed predation for two mammal — dispersed neotropical rain forest tree species

The effect of seed aggregation and distance from conspecific trees on seed predation was experimentally examined for two neotropical tree species, Macoubea guianensis (Apocynaceae) and Pouteria sp. (Sapotaceae) in a lowland tropical rain forest in northeastern Peru. Results of these experiments are discussed in the context of the Janzen-Connell model (Janzen 1970; Connell 1971), which predicts decreased seed survival near parent trees due to either density-or distance-responsive mortality, and Howe's model (Howe 1989) which predicts that trees with seeds dispersed in clumps (aggregated) will not suffer density-dependent predation, and will have higher survival of seeds near the parent tree than other trees. We also examined whether predation on seeds of these species was affected by seed placement in or near 30-m-wide strips regenerating after clear-cutting. Both species appeared to be mammal-dispersed but differed in how frugivores handled seeds, seed size, overall fruit crop size, and gemination time. Neither of the two species studied appeared to suffer seed predation in a manner predicted by the Janzen-Connell model, and patterns of seed predation for only one of the species was similar to predictions of Howe's model. For neither species did seed predation along the edge of, or in the center of, regenerating clear cuts differ from predation 15 m into the primary forest. For Pouteria, seed predation in and near regnerating strips was significantly greater than around forest trees, but the opposite pattern held for Macoubea. Overall, seed predation was much greater on Macoubea. The difference in seed predation for these two species was most likely a result of differences in the types of seed predators that attacked these two species.     

REPRODUCTIVE ATTRITION IN THE RARE CHAPARRAL SHRUB FREMONTODENDRON DECUMBENS LLOYD (STERCULIACEAE)

We examined reproductive attrition in Fremontodendron decumbens to characterize sexual reproduction in this rare California shrub. Reproductive individuals produced an average of 2,900 flower buds in a season, with no significant difference in bud production between two seasons. Because of intense insect predation, <;2% of initiated flower buds became mature fruits. A threefold decrease in predation of flower buds between seasons resulted in an increase in seed output the second season, indicating that seed production was partially predator-limited. Most seeds (97.8%) were dormant due to an impermeable seed coat. Breaking of the coat, mechanically or by heat, allowed high levels of germination. Chamise charate and ash added to the potting medium resulted in the highest level of germination and emergence. Rodents were more important than birds as seed predators, destroying 90% of seeds under parent shrub canopies within 8–10 months. Seeds already integrated into the seed bank were comparatively safe from predation, relative to newly added seeds. If predation was prevented, seeds were long-lived under field conditions (>;80% survived after 5.75 years). Most seedlings produced in unburned chaparral by planting heat-treated seeds in openings between shrubs were destroyed by predators (rodents and insects). All seedlings that escaped predation died during the summer drought. We concluded that sexual reproduction was limited by (in order of importance): 1) lack of fire, 2) predehiscence predation by insects, and 3) postdehiscence predation by rodents. Size distributions from two populations revealed that, despite the apparent absence of sexual reproduction in unbumed chaparral, two unbumed sites contained a large proportion of individuals in small size classes. Excavation of several small individuals demonstrated they were sprouts from the roots of nearby larger shrubs. Because asexual reproduction by rootsprouting circumvents the high attrition of sexual reproductive effort on unbumed sites, rootsprouting may be a significant reproductive strategy of some ‘sprouter’ species in chaparral.     

Allometric allocation in fruit and seed packaging conditions the conflict among selective pressures on seed size

Selective pressures on seed size could vary among the different stages of plant life cycles, so no simple relation could explain a priori its evolution. Here, we determined the relationships between seed size and two fitness components—seed dispersal and survival from predation—in a bird-dispersed tree, Crataegus monogyna. We interpret these relationships in relation to the patterns of mass allocation to fruit and seed components. Selection patterns were assessed at two levels (1) selection pressures on the parent tree; comparing seed dispersal efficiency among individual plants and (2) selection pressures at the individual seed level; comparing seed size variation (i) before and after dispersal, and (ii) before and after postdispersal seed predation. Dispersal efficiency (percentage of seed crop dispersed) was positively correlated with fruit mass and fruit width. Differences in crop size did not offset this effect, and larger seeds were overrepresented in the seed rain relative to the seed pool before dispersal. However, the advantage of larger seeds during the dispersal stage was cancelled later by an opposite selection pressure exerted by seed predators. As a result, smaller seeds had a higher probability of surviving postdispersal seed predation, establishing an evolutionary conflict imposed by the need for dispersal and the danger of being predated. Birds and rodents preferentially selected highly profitable fruits and seeds in terms of the relative proportion of their components. Larger fruits had a higher pulp to seed proportion than smaller ones, and all seeds had the same proportion of coat relative to the embryo-plus-endosperm fraction. Hence, although predator pressures were stronger than disperser ones, larger seeds invested proportionally less in structural defense than in dispersal.     

Effects of the seed predator Acanthoscelides schrankiae on viability of its host plant Mimosa bimucronata

Seeds of Mimosa bimucronata are heavily infested (pre-dispersal predation) by the bruchid beetle Acanthoscelides schrankiae in Brazil. In this study, firstly we set up experiments to assess seed germination under seven and six different light and temperature regimes, respectively, and then we evaluated the ability of seeds to germinate after predation. We tested the hypothesis that the non-predated seeds from infested fruits may respond differently when set for germination than those seeds of non-infested fruits. We also hypothesized that predation may increase the production of unviable seeds. Seeds under 18 hours of light presented the highest percentage of germination, and the alternating temperature 20-30 degrees C was considered as optimum for germination (abnormal seedlings were not considered as a successful germination). Germination of seeds from non-infested fruits was significantly higher than germination of non-predated seeds from infested fruits, and predation also caused a significant increase in the proportion of dead seeds. Our results also show a positive correlation between proportions of unviable seeds and predated seeds. These results demonstrated that seeds of M. bimucronata are strongly affected by predation because predated seeds did not germinate and non-predated seeds had their viability reduced when located in infested fruits, supporting our hypothesis.     

Dangerous life at the edge: Implications of seed predation for roadside revegetation

Question

Anthropogenic edges caused by transport infrastructure such as dirt roads and trails (also known as Soft Linear Developments; SLD) are pervasive in almost every terrestrial ecosystem. Revegetating these edges may reduce some of their negative effects, such as their permeability to biological invasions and detrimental effects on wildlife, potentially becoming suitable habitat for a broad range of species. Selecting species with low post‐dispersal seed predation rates may improve the effectiveness of revegetation programmes.

Location

Mediterranean scrublands in SW Spain.

Methods

We made offerings of a total of 16,000 seeds of eight species of fleshy‐fruit shrubs both along SLD edges and scrubland interiors in two independent blocks in each of three distant locations. Using four types of selective enclosure, we assessed the relative contribution of three seed predator guilds (ants, rodents and birds) to seed predation rates both along SLD edges and scrubland interiors.

Results

The effects of anthropogenic edges on seed predation rates were species‐specific. The large and hard‐seeded species Chamaerops humilis was not predated at all. Juniperus phoenicea and Corema album seeds had higher predation rates in scrubland interiors than in edges. The small‐seeded Rubus ulmifolius experienced relatively low seed predation rates compared to the other species. Predation rates for this species were higher along SLD edges than in scrubland interiors. Ants were the main seed predators in the area, and showed marked preferences for J. macrocarpa and C. album seeds at both SLD edges and scrubland interiors.

Conclusions

Our results show the strong context‐dependency of seed predation rates in both SLD edges and scrubland interiors, and thus the importance of well spatially and temporally replicated studies. Species with large and hard seeds may be good candidates for roadside revegetation programmes. However, the relative suitability of plant species would depend on the seed predator community. Our findings confirm that studies on seed predation may help planning cost‐effective species selection for edge revegetation efforts worldwide.     

Identification of a characteristic antioxidant,anthrasesamone F,in black sesame seeds and its accumulation at different seed developmental stages

Assay-guided fractionation of the methanol extract from black seeds of sesame (Sesamum indicum L.) led to the isolation of an active compound that had a 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity. This antioxidant was confirmed to be anthrasesamone F, an anthraquinone derivative previously isolated from different black sesame seeds and biogenetically related to other anthrasesamones in sesame roots. The radical scavenging assay showed that anthrasesamone F had more potent activity than Trolox. The content of anthrasesamone F in different parts and at different developmental stages of black sesame seeds was investigated to clarify the accumulation pattern of this antioxidant in the black seeds. Anthrasesamone F was localized in the seed coat of black seeds and accumulated after the seed coat color changed to black. The content of anthrasesamone F increased gradually with seed maturation and drastically on air-drying, the final stage in sesame cultivation.     

Early reduction of post-fire recruitment of Pinus nigra by post-dispersal seed predation in different time-since-fire habitats

This study analyses the effects of post-dispersal predation of Pinus nigra seeds on the initial recruitment of this species in areas burned by large wildfires, where P. nigra shows very low regeneration. In three different habitats obtained in a gradient of time since fire in Catalonia (NE Spain), we have evaluated the effects of seed predators (ants, rodents and birds) on post-dispersal seed removal and early seedling establishment of P. nigra by using selective exclosures limiting their access to seeds. Ants were the most efficient seed predator group, followed by rodents and birds. The contribution of each group to overall predation showed large seasonal variations. The first seeds dispersed in winter were mainly predated by rodents, which also registered their highest abundance in this season of the year. In spring, at the end of the natural dissemination period of P. nigra seeds, ants became the major predators, this fact coinciding with their increased abundance. Birds showed the lowest predation values. In the seedling establishment experiment, only in the exclusion treatment of the three predator groups was there initial establishment in all habitats, especially in the recently burned area, where there was seedling establishment in all exclusion treatments. The post-dispersal seed predation by different animal groups and low seedling emergence in the different habitats obtained in this study, together with the low seed availability of P. nigra seeds in burned areas, do not predict a favourable outlook for the natural post-fire recolonization of this species, which might even affect its overall distribution area in the region.     

A stochastic model of seed dispersal pattern to assess seed predation by ants in annual dry grasslands

A combined field experiment and modelling approach has been used to provide evidence that ants may be responsible for an observed lower patchiness and higher plant diversity in the neighbourhood of ant nests, within Mediterranean dry grasslands belonging to the phytosociological class Tuberarietea guttatae. The hypothesis was that seeds occurring in clumps may have a higher probability to be harvested than seeds having a scattered distribution. In order to test this hypothesis, four analysis steps were performed. First, pattern of seed production and dispersal of four species was recorded; two of them were more abundant next to ant nests (Tuberaria guttata, Euphorbia exigua), whereas the other two were more abundant away from ant nests (Bromus scoparius and Plantago bellardi). Second, a stochastic model was developed to simulate the observed dispersal patterns of each studied species. Third, 10 seed spatial arrangements in accordance to the distribution patterns created by the model were offered to ants and the location of predated seeds was recorded. Finally, the observed pattern of seed predation was matched to models performed by different distributions of probability. Results showed that the probability of being predated decreased as distance among seeds increased. This preference of ants for high concentration of food items holds down the dominant species sufficiently to allow the subordinates to survive, thus increasing diversity near nests. The observed higher frequency of small-seeded, small-sized, or creeping therophytes close to the ant nests can be therefore seen as an example of indirect myrmecophily.     

Empty Seeds Are Not Always Bad: Simultaneous Effect of Seed Emptiness and Masting on Animal Seed Predation

Seed masting and production of empty seeds have often been considered independently as different strategies to reduce seed predation by animals. Here, we integrate both phenomena within the whole assemblage of seed predators (both pre and post-dispersal) and in two contrasting microsites (open vs. sheltered) to improve our understanding of the factors controlling seed predation in a wind-dispersed tree (Ulmus laevis). In years with larger crop sizes more avian seed predators were attracted with an increase in the proportion of full seeds predated on the ground. However, for abundant crops, the presence of empty seeds decreased the proportion of full seeds predated. Empty seeds remained for a very long period in the tree, making location of full seeds more difficult for pre-dispersal predators and expanding the overall seed drop period at a very low cost (in dry biomass and allocation of C, N and P). Parthenocarpy (non-fertilized seeds) was the main cause of seed emptiness whereas seed abortion was produced in low quantity. These aborted seeds fell prematurely and, thus, could not work as deceptive seeds. A proportion of 50% empty seeds significantly reduced ground seed predation by 26%. However, a high rate of parthenocarpy (beyond 50% empty seeds) did not significantly reduce seed predation in comparison to 50% empty seeds. We also found a high variability and unpredictability in the production of empty seeds, both at tree and population level, making predator deception more effective. Open areas were especially important to facilitate seed survival since rodents (the main post-dispersal predators) consumed seeds mostly under shrub cover. In elm trees parthenocarpy is a common event that might work as an adaptive strategy to reduce seed predation. Masting per se did not apparently reduce the overall proportion of seeds predated in this wind-dispersed tree, but kept great numbers of seeds unconsumed.     

Effects of seed colour heterogeneity on germination behaviour of the desert plant Lotononis platycarpa (Fabaceae)

We aimed to determine the ecological role of three seed morphs observed for the first time in a desert population of Lotononis platycarpa (Fabaceae), with respect to their germination requirements. Seeds sorted by seed coat colour (olive green, orange and brown) were germinated under laboratory conditions under two photoperiods (12/12‐h light and continuous dark) and three alternating temperature regimes (15/25, 20/30, 25/35°C). We found that the three distinct seed types differ in their seed mass, germination percentage and speed of germination. Overall, the light‐incubated seeds germinated with higher percentages than seeds in the total darkness. Furthermore, seeds with orange coat germinated with higher percentages at 15/25 and 25/35°C (up to 60%, for both) and significantly faster than the other two colour morphs. Our results suggest an adaptive significance of seed colour heterogeneity in the harsh desert habitat inhabited by the study species.     

A preliminary investigation of pre-dispersal seed predation by Acanthoscelides schrankiae Horn (Coleoptera: Bruchidae) in Mimosa bimucronata (DC.) Kuntze trees

This is the first record of Acanthoscelides schrankiae Horn. feeding in seeds of Mimosa bimucronata (DC.) Kuntze. We investigated the pattern of oviposition and seed exploitation by A. schrankiae, and the distribution of mature fruits and seed predation in the inflorescences. We also compared the percentage of predated seeds, the total dry weight of fruits and non-predated seeds, the percentage of aborted seeds, and the percentage of non-emergent insects, among different quadrants of the M. bimucronata canopy. To determine the occurring species, the emergence of bruchids and parasitoids was observed in the laboratory, resulting altogether, only in individuals of A. schrankiae and Horismenus sp. (Hymenoptera: Eulophidae) species, respectively. Mean number of fruits produced in the median region of inflorescence was significantly higher than in the inferior and superior regions, and the frequencies (observed and expected) of predated and non-predated seeds differed among the different regions of inflorescence. Females of A. schrankiae laid their eggs on fruits, and larvae, after emergence, perforated the exocarp to reach the seeds. Most fruits presented one to three eggs and only one bruchid larva was observed in each seed. The highest value of the rate "number of eggs/fruit" and the highest percentage of predated seeds were recorded in April. Dry weight of fruits (total) and seeds (non-predated), proportions of predated seeds, seed abortions, and non-emergent seed predators, were evenly distributed in the canopy.     

Seed removal,seed dispersers,and the allocation of tissues in Myrtaceae seeds

To avoid seed predation, plants may invest in protective seed tissues. Often related to seed size, allocation in seeds' physical defenses can also be influenced by dispersers. We explore the relationships between seed traits (seed mass and hardness) and seed removal in 22 Myrtaceae species of the Brazilian Atlantic Forest, a dominant and diverse fleshy-fruited taxon dispersed by birds, rodents, and other mammals. Our goal is to understand how seed traits influence seed removal rates, and whether dispersers can affect tissue allocation in the seed coat. Seeds were exposed to field removal experiments. In the laboratory, total seed mass and seed coat mass were obtained. To evaluate the influence of seed traits on removal, we performed Kruskal–Wallis and Simple Linear Regression tests. We assessed seed coat and seed mass covariation through standardized major-axis allometric regressions. Harder seeds were larger than softer ones. Seed traits affect removal rates, as tougher and heavier seeds had lower removal. Seed mass significantly predicts seed coat proportion in seven of the 14 species tested. Bird-dispersed species tend to exhibit lower proportions of seed coat as seed mass increases, whereas rodent-dispersed species apparently present the opposite trend, with seed coat proportion increasing with seed mass. Such difference may be caused by the contrasting seed predation pressure represented by birds and rodents. Energy allocation for defense, expressed in seed coat proportion, is greater in large seeds, as these are mostly dispersed by rodents whose propensity to cache and disperse seeds is greater for large and well-protected seeds.     

Seed predation of Copaifera langsdorffii (Fabaceae): a tropical tree with supra‐annual fruiting

Seed predation is an important ecological and evolutionary force that directly affects the distribution of plant species. Copaifera langsdorffii is a tropical tree species with supra‐annual fruiting, which has its seeds predated by a specialist endogenous insect (Rynochenus brevicollis: Curculionidae) in the Brazilian savanna. Three hypotheses were addressed: (i) the predator satiation hypothesis, (ii) the resource concentration hypothesis and (iii) the larger seed predation hypothesis. A total of 112 individual C. langsdorffii were monitored monthly from January to August during four consecutive years (from 2008 to 2011) to determine the presence of fruits on each plant. All trees produced fruits in the year 2008, whereas none of them produced flowers or fruits in 2009 or 2010. Moreover, only 65 individuals (58%) marked in 2008 produced fruits in 2011. The number of fruits per plant was approximately 21% greater in 2008 than in 2011, while the percentage of seed predation was 76% greater in 2011, thereby supporting the predator satiation hypothesis. The percentage of seeds predated was not affected by the number of fruits per plant. Therefore, our data did not support the resource concentration hypothesis. Plants producing large seeds experienced more seed predation by R. brevicollis, supporting the larger seed predation hypothesis. In addition, we also observed a positive relationship between seed volume and adult R. brevicollis weight. This study demonstrates the importance of supra‐annual fruiting for increasing survivorship of C. langsdorffii seeds both at the individual and the population level, and suggests that seed predators select plants producing large seeds as a way of increasing the number of offspring.     

Assessing ant seed predation in threatened plants: a case study

Erodium paularense is a threatened plant species that is subject to seed predation by the granivorous ant Messor capitatus. In this paper we assessed the intensity and pattern of ant seed predation and looked for possible adaptive strategies at the seed and plant levels to cope with this predation. Seed predation was estimated in 1997 and 1998 at the population level by comparing total seed production and ant consumption, assessed by counting seed hulls in refuse piles. According to this method, ant seed predation ranged between 18% and 28%. A more detailed and direct assessment conducted in 1997 raised this estimate to 43%. In this assessment spatial and temporal patterns of seed predation by ants were studied by mapping all nest entrances in the studied area and marking the mature fruits of 109 reproductive plants with a specific colour code throughout the seed dispersal period. Intact fruit coats were later recovered from the refuse piles, and their mother plants and time of dispersal were identified. Seeds dispersed at the end of the dispersal period had a greater probability of escaping from ant seed predation. Similarly, in plants with late dispersal a greater percentage of seeds escaped from ant predation. Optimum dispersal time coincided with the maximum activity of granivorous ants because, at this time, ants focused their harvest on other plant species of the community. It was also observed that within-individual seed dispersal asynchrony minimised seed predation. From a conservation perspective, results show that the granivorous ant–plant interaction cannot be assessed in isolation and that the intensity of its effects basically depends on the seed dispersal pattern of the other members of the plant community. Furthermore, this threat must be assessed by considering the overall situation of the target population. Thus, in E. paularense, the strong limitation of safe-sites for seedling establishment reduces the importance of seed predation.     

Postdispersal seed predation and seed viability in forest soils: implications for the regeneration of tree species in Ethiopian church forests

Almost all dry Afromontane forests of Northern Ethiopia have been converted to agricultural, grazing or scrub lands except for small fragments left around churches (‘Church forests’). Species regeneration in these forests is limited. We investigated (i) how intense postdispersal seed predation was in church forest, and if this seed predation varied with species and/or habitat, and (ii) for how long tree seeds maintained their viability while buried in forest soil. In the seed predation experiment, we monitored seeds of six tree species in four habitats for a period of 14 weeks (the peak seeding season). In the seed viability experiment, we assessed seed viability of five species in four habitats after being buried 6, 12, or 18 months. Ninety‐two percent of the tree seeds were predated within 3.5 months. Predation was mainly dependent on species whereas habitat had a weaker effect. Seed viability decreased sharply with burial time in soil for all species except for Juniperus. To minimize seed availability limitation for regeneration of such species in the forest, the standing vegetation needs to be persistently managed and conserved for a continuous seed rain supply. Additional seed sowing, and seed and seedling protection (by e.g. animal exclosures) may increase successful regeneration of important species in these forests.     

Seed Removal and Predation as Factors Affecting Seed Availability of Tree Species in Degraded Habitats and Restoration Plantings in Rainforest Areas of Queensland,Australia

The post‐dispersal removal or predation of seeds of native tree species was investigated in Queensland, Australia, at degraded habitats and rainforest restoration sites where direct seeding might be used to facilitate tree regeneration (old fields or open habitats, lantana thicket, rainforest edge, and 5‐ and 10‐year‐old restoration plantings). Seed removal/predation was assessed in relation to tree seed weight and canopy density of the habitats during the wet season period. Results indicated that seed removal/predation imposes limitations on seed availability, particularly for small seeded species. In most situations, larger seeds were less removed/predated, most likely due to the more limited range of large seed consumers. The use of large, hard‐coated seeds may potentially reduce seed loss in open situations (from both seed removal and desiccation), unless large seed consumers frequent the site. Canopy cover exerted an influence on seed removal/predation, though trends varied in relation to site and the time of season. Broadcast sowing of seed under planted tree canopies at the more advanced stages of closure may in some areas result in higher seed removal/predation. Likewise, seeding in areas dominated by woody weeds may result in high seed losses to consumers such as rodents. Results suggested that undertaking direct seeding to coincide with the maximal period of fruit production may in some situations be beneficial to minimize seed loss. Overall, site context, canopy cover, and species selection appear to be important considerations when aiming to reduce loss of seeds to animal seed consumers in restoration work.