Seed Predation

Predispersal seed predation may have implications for plant population dynamics and the evolution of plant traits, but assessing the level of seed predation for an individual plant is not always straightforward. Seeds of Lotus corniculatus (Fabaceae) are often only partially eaten by a weevil seed predator, Apion loti. Samples of these seeds were tested for viability and subsequent seedling vigour. A large proportion of these damaged seeds were viable, and the resulting seedlings almost as vigorous as those from undamaged seeds. The ubiquity of these findings, and their ecological significance, is discussed.(Received January 31 1996)(Accepted February 28 1996)

The tree species Xylocarpus granatum is commonly described as occurring in the upper intertidal zone of mangrove forests, but mature trees are occasionally found at lower elevations. In the Utwe River basin, on the Pacific island of Kosrae, we investigated the relative importance of several biotic and abiotic factors that may control the intertidal distribution of X. granatum. Factors we evaluated included differential seed predation across the lower, mid, and upper intertidal zones and seedling responses to salinity, tidal flooding, and shade. Seed predation was 22.4% over the first 34 days and varied little among zones or in gaps versus under the forest canopy. By day 161, there were still no differences in seed mortality, but a significant difference was found in seedling establishment, with much greater establishment in the upper intertidal plots. X. granatum seedlings in a greenhouse experiment exhibited greater growth in freshwater than seedlings in 23 ppt salinity, which is t...

Effects of tacuarembó (Chusquea ramosissima, Poaceae) on seed dispersal process in Misiones Forest: Seed dispersal by mammals results spatially heterogeneous since some areas of mammals' territories that are avoided by them. Therefore, seed arrival is high in areas frequently used by the animals and negligible in the avoided areas. Besides, seeds in mammals' scats can suffer high levels of removal

Los bosques de Prosopis flexuosa proporcionan múltiples bienes y servicios. Actualmente, sufren una fuerte retracción debido a un uso histórico extractivista y se hace necesario promover la conservación y el manejo sostenible de los bosques como sistema. El objetivo del trabajo es sintetizar
el conocimiento disponible acerca de las interacciones mutualistas y antagonistas entre mamíferos, frutos y semillas de P. flexuosa, comparando con estudios realizados en otras especies de Prosopis de Argentina. Se considera a dos grupos de consumidores oportunistas de frutos: almacenadores
en cúmulos dispersos y frugívoros. Los roedores pequeños (como Eligmodontia typus y Microcavia australis) son dispersores de semillas porque depredan pocas semillas y almacenan el resto en cúmulos sobre la superficie del suelo. Mamíferos frugívoros oportunistas silvestres (Dolichotis patagonum, Lepus europaeus, Lycalopex griseus, Lama guanicoe, etc.) y domésticos (burro, caballo, vaca) son dispersores endozoocóricos y proporcionan beneficios como el traslado de grandes cantidades de semillas, la eliminación de estructuras que mantienen la dormición y la desinfección
de semillas atacadas por insectos. Sin embargo, la endozoocoria tiene costos sobre la viabilidad y la capacidad germinativa de las semillas. Ante un panorama de continuos cambios en el uso de la tierra y de cambio climático global, el conocimiento acerca del espectro diverso de animales que proporcionan el beneficio de dispersión de semillas aporta bases científicas para considerar que la biodiversidad asociada a los bosques debe incluirse en la gestión y conservación de los mismos.

Seed predation by arthropods can contribute in regulating population and community dynamics of weeds. While the role of insects, and especially ground beetles (Coleoptera: Carabidae) as seed predators in crop fields is well studied, the drivers of predation stability and the relationships between species diversity and predation are less understood. The aims of the study were: 1) to unveil the direct relationships between predator community diversity and seed predation intensity and stability, and 2) to test the effects of soil disturbance (conventional vs. conservation tillage) and distance from field margin on seed predator communities and predation. Seed pre-dation was measured using seed cards, and predator communities were sampled using pitfall traps over two years. Granivorous ground beetles, ants and crickets were the most abundant seed predators in both conventional and conservation tillage fields. Abundant and diverse predator communities were beneficial to predation intensity and stability. However, in communities dominated by large predators, an increase in number of species was related to a partial suppression of seed predation. Soil disturbance per se did not influence the overall predator community composition and predation, but it modified their spatial patterns within the fields. At the margins of conventional tillage fields, predation was lower and patchier than at the margins of conservation tillage fields. However, predation increased more steeply towards the center of conventional tillage field. Our results could find applications in sustainable weed management through biological control, as well as in better understanding the role of functional diversity in regulating ecosystem services.

Introduced mammalian herbivores are changing the structure and composition of New Zealand's forest ecosystems and may modify forest succession after natural disturbances. We studied how introduced ungulates (red deer and feral pigs) and rodents (rats and house mice) affected the rate of recovery (i.e. the engineering resilience) of the forest understorey following artificial disturbance. We imposed disturbances by clearing understorey

We compared the feeding ecology of the Hali–Hali community of bonobos (Pan paniscus) at Kokolopori, a new field site in the Democratic Republic of the Congo, between two periods 5 months apart. During the first study period (SP1), bonobos relied heavily on the dry seeds of Guibourtia (Caesalpiniaceae), mostly eaten from the ground. The second period (SP2) was characterized by high consumption of ripe tree fruit. Terrestrial herbaceous vegetation (THV) contributed little to the diet in either study period. The low amount of ripe fruit and the high reliance on seeds in the diet during SP1 were associated with high cortisol production and low levels of urinary C-peptide in females, suggesting nutritional stress. However, female gregariousness was not constrained during the fruit-poor period, probably because high seed abundance on the ground ameliorated scramble feeding competition. This is the first description of extensive seed predation by bonobos. It suggests that bonobo feeding ecology may be more similar to that of chimpanzees than previously recognized.

Palms are considered key species in tropical forests and represent a source of food for the community of frugivores in times of scarcity. Palms have also been used as a model to investigate how the processes of dispersal and seed predation are affected by fragmentation and alteration of tropical forests. This study examines the dispersal and seed predation of Syagrus romanzoffiana in two insular environments of different sizes (1500 ha and 50 ha) and faunal compositions, both located in the Brazilian Atlantic rainforest in Santa Catarina State, Brazil. We recorded 13 species of animals considered consumers and dispersers of fruits and seeds of S. romanzoffiana at the larger study area (Peri Lagoon Municipal Park, Santa Catarina Island) and five species on Campeche Island. In these areas, the rates of dispersal were high (Peri 57.5% to 75.5% and Campeche 81.5% to 93.0%, based on the removal experiments). In the smaller area, despite the low faunal richness, the coatis (Nasua nasua), introduced in the island were important seed dispersers. Only in Peri occurred predation by rodents (rates of 4%) due to the presence of agoutis (Dasyprocta azarae) and there was no post-dispersal predation by insects. The greatest loss of seeds (52% in both locations, based on sampling of seeds accumulated under parent plants) were caused by predation of Revena rubiginosa (Coleoptera, Curculionidae), of which oviposition occurs in the pre-dispersal phase. Besides this factor, about 40% of the seeds showed up without endosperm. However, high seed production seems to compensate for these losses, with significant seedling stock of S. romanzoffiana in both areas.Palmeiras são consideradas espécies-chave em florestas tropicais representando fonte de alimento para a comunidade de frugívoros em épocas de escassez. Palmeiras também têm sido usadas como modelo de estudo na avaliação de como os processos de dispersão e predação de sementes são afetados pela fragmentação e alteração das florestas tropicais. Este estudo examina a dispersão e predação das sementes de Syagrus romanzoffiana em dois ambientes insulares de diferentes tamanhos (1500ha e 50ha) e composições faunísticas, ambos localizados em área de Mata Atlântica no Estado de Santa Catarina, Brasil. Foram registradas 13 espécies de animais considerados consumidores e dispersores dos frutos e sementes de S. romanzoffiana na maior área estudada (Parque Municipal da Lagoa do Peri, Ilha de Santa Catarina) e cinco espécies na Ilha do Campeche. Nestas áreas, as taxas de dispersão foram altas (Peri 57,5% a 75,5% e Campeche 81,5% a 93,0%, com base em experimentos de remoção). Na menor área, apesar da baixa riqueza faunística, os quatis (Nasua nasua), introduzidos nessa ilha, foram importantes dispersores das sementes. Somente ocorreu predação por roedores no Peri (taxas de 4%) devido à presença de cotias (Dasyprocta azarae) e não houve predação pós-dispersão causada por insetos. A maior perda de sementes (52% em ambas as localidades, com base em amostragem de sementes acumuladas sob plantas-mãe) foi causada por predação de larvas de Revena rubiginosa (Coleoptera, Curculionidae), cuja oviposição ocorre na fase de pré-dispersão. Além deste fator, cerca de 40% das sementes mostravam-se sem endosperma. Contudo, a alta produção de sementes parece compensar essas perdas, havendo expressivo estoque de plântulas de S. romanzoffiana em ambas as áreas.

Post-dispersal seed predation can severely limit plant recruitment, but its ultimate impact could be modulated by environmental factors and by the composition of the granivore guild. Here, we analyze the relative impact of the non-native wild boar and native rodents on seed survival and seedling establishment of the mast conifer Araucaria araucana. Predation, seed survival and seedling establishment were measured at different microsites and distances from 11 isolated trees in Lanín National Park (Argentina) over a period of marked fluctuation in seed production. Wild boar consumed between 10 and 30% of available seeds on a 13-day period, threefold less than rodents. Wild boar predation was mainly affected by forest canopy composition, while microsite conditions influenced both kind of predators, with high chronic rodent predation underneath dense vegetation and moderate (but interannually variable) wild boar predation at poorly vegetated microsites. Predation by rodents was spatially clustered at the microsite scale, particularly during non-mast years; while predation by wild boar was spatially structured at a coarser scale and less modified by masting. The exclusion of wild boar increased significantly the amount of surviving seeds, resulting in higher seedling establishment in intermediate production years, but not affecting it during the mast year. At tree level, seedling establishment was negatively correlated with predation; while at stand level, cone production accounted for most of the seedling establishment variability. The current wild boar population may not be affecting the seedling establishment at population scale, probably due to minimization of its impact by the Araucaria masting strategy. However, if wild boar population numbers continue to increase, their impact may shift from individual tree scale to stand scale, threatening Araucaria forest regeneration.

Dry tropical forests are among the most threatened ecosystems at this moment and large areas have been converted rapidly into grass lands, secondary forest, savanna or agricultural land. Knowledge of seed germination and seedling establishment is required for the success of these forests and for a sustainable management of these forests. Fieldwork of this study was conducted in tropical dry forest INPA, eastern Bolivia, during a period of four months (November 2004 – February 2005). A spiny bromeliad (Pseudananas sagenarius) covers large areas in this forest and is believed to reduce tree regeneration of commercially important timber species. Seed predation was evaluated in areas containing three different bromeliad covers; high density (70-100% bromeliad), low density (0-30% bromeliad) and no cover (0% bromeliad). Seeds of two important timber species were artificially dispersed and the number of removed seeds was followed over 30 days. The time of discovering seeds by seed removers did not vary significantly among bromeliad densities, while removal rates during the experiment and removal percentages at the end of the experiment significantly differed between areas with and without bromeliad cover. Though, not the density, but only the presence of bromeliad seemed to have an effect on seed predation. Herbivory, survival and growth of seedlings were evaluated using four treatments consisted of the four possible combinations between bromeliad and exclosure. Herbivory, survival and growth of seven important timber seedling species were measured once in November 2004 and second in January 2005, but showed no significant affect on the treatments. Survival could not be tested on significance, but seemed to react on the treatments. Seedlings protected from herbivores showed no effect on bromeliad cover, while unprotected seedlings in areas with removed bromeliad showed a greater number of survivors. Herbivory of seedlings reduced seedling survival and absolute shoot growth. Measuring several microhabitat characteristics gave more insight in the distribution of bromeliad through the forest. Bromeliad densities are greater in the higher parts of the forest which contain less soil moisture contents and experience higher seed removal rates. At these sites, the ground cover with herbs, the number of seedlings and seedling species is lower. This study supports the hypothesis that seed predation reduces the number of available seeds for germination and with this tree regeneration. However, the presence of bromeliad did not show to have any effect on the herbivory, survival and growth of seedlings.
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Abstract• Tree recruitment in Mediterranean savannas is generally hampered, in contrast with the original oak forests where these savannas are derived from. We asked whether this difference in recruitment success can be explained by differential post-dispersal survival. For one year we monitored experimentally cached holm oak acorns in a savanna–forest ecosystem in Central Spain, and recorded cache pilferage, type of pilferer, boar rooting, seedling emergence, seedling survival and the cause of mortality.

ACKNOWLEDGMENTS The authors,wish,to thank,Dr. Eleanor,Groden,and,Dr. Eric Gallandt,for critically reviewing,the manuscript,and,Dr. Richard Storch for editorial assistance. This work,was funded,by the,United States Department,of Agriculture,from,a special,CSRS research grant,for potato ecosystems. Contents Contents Contents Contents Contents Introduction,...................................................................5 Predispersal,Seed Predation .........................................5 Postdispersal,Seed Predation ......................................10 Seed Predation And Plant Population,Dynamics,.......15