Seed dispersal in New Zealand relies on a different guild from the one present before the arrival of humans into the islands. Post-dispersal biotic and abiotic filters have also changed due to the introduction of seed predators and herbivores. The aim of this thesis was to evaluate the actual contribution of seed dispersers to the patterns of seed fall and to understand the effects of biotic (seed density, predators, distance from conspecifics) and abiotic (pH, canopy openess, etc) factors on seed and seedling survival. I expected that tree species with different fruit sizes would be selected by different assemblages of dispersers, therefore being deposited and recruiting differentially on the forest floor. I analyzed the changes in small-scale seed diversity with the use of seed traps during two seasons in two 0.36 ha plots in a mixed broadleaf-podocarp temperate forest. The diversity of seeds was lower for in-fruit seeds (1.40 species per grid-cell) than for bird-dispersed seeds (2.62). The dominant species D. cupressinum was dispersed towards con- and heterospecific canopies (wind-dispersed trees Weinmannia racemosa and Metrosideros umbellata), giving a probable mechanism for the observed increase in finescale seed diversity. Then, using a 12-year dataset on seed fall I analyzed the changes in ground-level seed heterogeneity generated by bird-dispersed seed rain (propagule-scale) relative to the canopy composition (adult-scale) on six tree species. A Non Metric Multidimensional Scaling analysis demonstrated that the differences in species composition between sampling points (seed traps) were larger for tree canopies than for dispersed seeds. Different tree species acted as seed importers and/or exporters, although these patterns were not explained by fruit size or the richness of the disperser assemblages. I also investigated the effects of seed and seedling density on seed predation, seedling emergence and seedling survival to 12 months of five tree species. Seed predation increased with seed size, and it was higher at high density only for the largest-seeded species Beilschmiedia tawa and Prumnopitys ferruginea. Access of seed and seedling predators to the propagules was the main factor affecting seedling emergence and seedling survival. Abiotic variables were important for germination and seedling survival of the two small-seeded species, but only biotic predictors (mammalian exclosure and density) were important for medium and large-seeded species. Finally, using a split-plot experimental design I measured the effects of (a) the presence of conspecific canopy, (b) high conspecific seed densities and (c) introduced (or invasive) mammal access on seedling emergence and seedling survival (Janzen-Connell effects). Distance effects were stronger than density effects, and mediated by native and exotic predators. Final survival under conspecifics was strongly reduced in both species, with zero survival of B. tawa under conspecifics, and near zero (2/896) under D. dacrydioides. Seed dispersal service in New Zealand is still enough to produce changes in the spatial pattern of seed deposition in the forest. Post-dispersal processes such as seed predation and herbivore are having strong impacts on the survival and potential recruitment of plant species. Large-seeded trees are the most affected in terms of the impact of introduced mammals on seed predation, but seedling survival is affected independent of seed size. However, it is unknown how different these ecological processes are from the original situation without pests in New Zealand. The results of my research can contribute with valuable information for future research trying to understand the consequences of seed dispersal for recruitment, as well as inform complex models that try to predict the long-term impacts of the exotic mammals introduced in New Zealand.

The Cameroon Highlands that run along the Cameroon-Nigeria border are an important source of biodiversity. Not only are they rich in species and high in endemics, but biota from West Africa have not been studied as extensively relative to other parts of the Afrotropics, or the tropics in general. Threatening these rare and diverse habitats is anthropogenic pressure, which fragments forests and changes local animal communities. This thesis wished to address the impact of humans on seed dispersal and recruitment processes on selected tree species in forests on the Mambilla Plateau - a montane region in Nigeria's north-east. Research was conducted at Ngel Nyaki Forest Reserve, a conservation area established by the Nigerian Montane Forest Project. The reserve comprises a moderately-large forest patch (Ngel Nyaki Forest) and many small riparian fragments embedded in a grassland matrix. Cattle grazing and burning of this grassland are major threats to the survival of forest in this area.Hunting of local wildlife for bushmeat is also of concern, considering many of the region’s large-mammalian fauna are now locally extirpated (e.g. elephants) or at low abundances (many primate species). Loss of large-bodied frugivorous species has the potential to negatively impact the recruitment of large-seeded tree species that solely rely on them as seed dispersers. In this study, the ability for scatterhoarding rodents to act as surrogate dispersers for large-seeded species is tested. While much research has been carried out on secondary rodent dispersal in the Neotropics, work in the Afrotropics is still in its infancy. Because the outcome of plant-rodent interactions (i.e. predated or dispersed) may vary with season, habitat, or traits of the seed species in question, a number of experiments were established to quantify how local rodents at Ngel Nyaki may or may not be acting as effective dispersers. Additionally, the benefits of rodent dispersal were examined by creating an experiment that simulated secondary dispersal on seedling recruitment. The results of this study demonstrated that rodents can act as effective dispersers in Afromontane forests, but this is influenced by habitat, seasonal abundance of resources, and palatability of seed species. Furthermore, it was demonstrated that burial of seeds by rodents can increase the establishment probability of a seed by protecting it from removal by other rodents. However, while rodents play a strong driver of seed survival, it was also demonstrated that seedling mortality factors (such as herbivory) can also be heavy filters to seedling success. It is hoped that the results of this study will help to inform better management decisions and understand how the composition of the forest might change in the future.

Orobanche ramosa L. is an annual, parasitic weed present in the western Murray-Mallee region of South Australia. A quarantine zone was established to encompass all known infestations, and has been adjusted over time as new infestations have been discovered. The movement of fodder, machinery, grain and straw, horticultural crops, livestock, and soil is controlled by strict quarantine procedures, to prevent further spread across the landscape. O. ramosa presents a unique situation for weed managers: plants are obligate parasites, relying entirely on broadleaved hosts for their water and nutrition; and seeds are tiny (0.3 mm), produced in large numbers (up to 100 000 seeds per plant), and are long-lived, persisting in the soil seed bank for up to 13 years. The dispersal vectors for O. ramosa in South Australia are the focus of this Master’s thesis. Two dispersal vectors were chosen for investigation: sheep and wind. Sheep were examined as possible vector for seeds, both via the gut (internal transport, or endozoochory) and via adhesion on the external surface of the animal (external transport, or epizoochory). Internal transport via sheep was investigated with a classic gut-passage experiment, which showed a peak in excretion of weed seeds at day 2, reducing to zero seeds excreted at day 8, and a half-life of 2 days. Two phases of external transport on sheep was studied: attachment and retention. Attachment was confirmed by finding seeds on the body wool and feet of sheep that had been kept for 7 days on soil with an O. ramosa seedbank. Seed retention was confirmed by placing seeds onto the body and still finding them in wool samples after 7 days. Wind was the other dispersal vector investigated for O. ramosa. A survey of natural wind dispersal was conducted, which confirmed wind as a vector and allowed trap design to be tested. Then a portable field-based wind tunnel was used to investigate the effects of ground cover (bare ground and cereal stubble) and wind speed (low, medium and high) on wind dispersal of O. ramosa seeds. For the stubble treatments, more seeds were trapped within the tunnel, and on bare ground more seeds were trapped exiting the tunnel. Importantly, the data showed that low wind speeds readily move O. ramosa seeds, and that the seeds are capable of aerodynamic lift in the wind profile. Results are discussed in the context of dispersal biology, quarantine procedures, and future work that would further refine knowledge of likely dispersal vectors for O. ramosa. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1459246 / Thesis (M.Sc.) -- University of Adelaide, School of Earth and Environmental Sciences, 2009

Made available in DSpace on 2014-06-11T19:22:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-05-26Bitstream added on 2014-06-13T20:10:10Z : No. of bitstreams: 1 gonzalez_sp_me_sjrp.pdf: 662763 bytes, checksum: b898062920cfef6accecbc5572efdaaa (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A rápida perda de diversidade biológica nos trópicos através da fragmentação de habitats pode ser revertida com o uso de técnicas de nucleação. Nesse sentido, um dos processos de facilitação é o uso de poleiros naturais e artificiais. Este se beneficia da natureza potencialmente dispersora de aves frugívoras. No presente estudo foram testadas as seguintes hipóteses: 1) famílias de aves menos dependentes de habitats florestais e com maior amplitude de itens alimentares (Turdidae e Tyrannidae) são mais eficientes na dispersão de sementes sob poleiros localizados em áreas degradadas; 2) famílias de aves que ocupam preferencialmente o interior de florestas e cuja dieta é composta principalmente por frutos (Ramphastidae e Pipridae) são mais eficientes na manutenção de remanescentes florestais. Esta pesquisa foi executada por meio de extensa revisão bibliográfica com área de abrangência exclusiva em território brasileiro. Comparou-se a contribuição potencial de quatro famílias que consomem frutos para a dispersão de sementes. O foco do estudo foram suas características de uso de hábitat e dieta. Concluiu-se que houve dicotomia entre famílias frugívoras especialistas e generalistas, quanto às suas características como dispersoras de sementes. Ramphastidae e Pipridae, classificados como essencialmente frugívoros, tiveram maior ocupação de ambientes florestais, menor flexibilidade na ocupação de habitats e estratos florestais, maior sensibilidade a alterações antrópicas, atuando basicamente na manutenção de ambientes florestais. Já as famílias generalistas Turdidae e Tyrannidae, com menor sensibilidade a alterações antrópicas, ocupação de ambientes com diversos graus de cobertura vegetal e estratos... / The rapid loss of biological diversity on the tropics through habitat fragmentation can be reverted using nucleation techniques. In this regard, one of the facilitation processes is the use of natural and artificial pearches. This technique takes advantage of the potential seed dispersal nature of frugivorous birds. In the present study the following hypotheses have been tested: 1) families of birds less dependent of forest habitats and with more amplitude of food items (Turdidae and Tyrannidae) are more efficient spreading seeds by the pearchs located in degraded areas; 2) Birds that preferably occupy the interior of forests and whose diet is mainly compounded by fruits (Ramphastidae and Pipridae) are more efficient on the maintenance of forest remnants. This research was produced by means of extensive bibliographic review, regarding the Brazilian territory as the study`s coverage area. The potential contribution of four families that consume fruits causing the dispersal 3 of seeds has been comparatively analyzed. The focus of this study was mainly their characteristics of usage of the habitat and diet. In conclusion, it was noticed a dichotomy among specialized and generalist frugivorous families regarding their characteristics as seed spreaders. Ramphastidae and Pipridae, classified as essentially frugivorous, had wider occupation of forestal environments, narrower flexibility on the occupation of habitats and forestal stratum, bigger sensibility to anthropic change, basically acting on the maintenance of forestal environments. On the other hand, the generalist families Turdidae and Tyrannidae, with lower sensibility to anthropic changes, environment occupation with diverse degrees of plant coverage and strata, including degraded areas. Turdidae and Tyrannidae are also the main occupiers of natural and artificial... (Complete abstract click electronic access below)

Submitted by VANESSA ELLEN WENDT CAMPOS null (vanessaellen@hotmail.com) on 2016-07-14T18:11:05Z No. of bitstreams: 1 Vanessa_Completo.pdf: 3530663 bytes, checksum: fa3beebf319fc93620723a321d5c7529 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-07-18T20:26:08Z (GMT) No. of bitstreams: 1 campos_vew_me_rcla.pdf: 3530663 bytes, checksum: fa3beebf319fc93620723a321d5c7529 (MD5) / Made available in DSpace on 2016-07-18T20:26:08Z (GMT). No. of bitstreams: 1 campos_vew_me_rcla.pdf: 3530663 bytes, checksum: fa3beebf319fc93620723a321d5c7529 (MD5) Previous issue date: 2016-03-30 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / As florestas tropicais representam um dos biomas mais ameaçados pelas ações antrópicas no mundo. Os primatas representam 40% da biomassa de vertebrados frugívoros nas florestas tropicais, mas mais da metade das espécies estão ameaçadas de extinção. Tendo em vista a importância dos primatas no funcionamento dos ecossistemas devido a sua função de dispersores de sementes, é de extrema relevância entender como a fragmentação das florestas tropicais afetam as comunidades de primatas e suas funções. Portanto, nossos objetivos são: 1) analisar a relação entre diversidade funcional e filogenética de primatas e como esses índices são influenciados pela riqueza; 2) determinar o efeito da fragmentação das florestas tropicais na riqueza específica e funcional dos primatas; 3) determinar quais características funcionais são perdidas com a fragmentação, na Amazônia e na Mata Atlântica brasileira. Para isso, montamos bancos de dados de ocorrência dos primatas e de suas características funcionais ligadas à dispersão de sementes para gerar os índices de diversidade funcional (FD), regularidade funcional (FEve) e divergência funcional (FDiv) e relacioná-los com métricas da paisagem: área do fragmento, isolamento médio entre os fragmentos, distância em relação à zona urbana, distância à floresta contínua, conectividade funcional e porcentagem de cobertura vegetal no entorno do fragmento. A diversidade funcional dos primatas é fortemente correlacionada com a diversidade filogenética (R2= 0.94 e p<0.001). A redução da área dos fragmentos e da conectividade funcional, assim como o aumento do isolamento médio entre os remanescentes florestais diminuem a diversidade (FD), a regularidade (FEve) e a divergência funcional (FDiv) dos primatas. As espécies de primatas de grande porte que possuem grandes áreas de vida e que dispersam grandes sementes são as espécies mais prejudicadas pela fragmentação. Nosso trabalho permitiu ressaltar que além da perda de riqueza específica de primatas, a fragmentação nas florestas tropicais também afeta o serviço de dispersão de sementes, o que, consequentemente, pode alterar a estrutura das comunidades vegetais. / Tropical forests are the most threatened biome by human activities worldwide. Primates represent almost 40% of the frugivore vertebrate biomass in tropical forests and more than half of their species are threatened by extinction. Given the importance of primates as seed dispersers for the ecosystem functioning, it is extremely important to understand how the fragmentation of tropical forests affects primate communities and the functions they provide. Therefore, this project aims at: 1) analyzing the relationship between primate functional and phylogenetic diversities and how those indices are influenced by species richness; 2) determining the influence of forest fragmentation on primate species richness and functional diversity; 3) determining which functional traits are lost with habitat fragmentation, in Amazonian and Atlantic Forests of Brazil. To do this, we built a database of primates’ occurrence and their functional traits related to seed dispersal to compute indices of functional diversity (FD), functional evenness (Feve) and functional divergence (FDiv). Then, we related these indices to landscape metrics: patch size, average isolation between patches, distance to the nearest urban area, distance to the nearest continuous forest, functional connectivity and percentage of forest cover surrounding the fragment. Functional diversity is strongly correlated with phylogenetic diversity (R2= 0.94 e p<0.001). The decrease of fragment areas and functional connectivity, and the increase of average isolation between forest remnants, reduce primate functional diversity (FD), regularity (FEve) and divergence (FDiv). Large primates with large home ranges that disperse large seeds are the most affected by fragmentation. Our results enable highlighting that beyond the loss of primate species richness, the fragmentation of tropical forests also affect seed dispersal service, which consequently may alter the structure of plant communities. / FAPESP: 2014/14739-0 / CNPq: 830816/1999-2

The Janzen-Connell mechanism is proposed to maintain plant diversity: predators and diseases of seeds reduce the number of seeds that survive near a parent tree, but allow seeds far from the parent tree to grow into adulthood. In the area where seeds don’t survive, seedlings from other tree species which are not affected by the seed consumer can grow. At large scales, this effect is thought to increase overall plant diversity. Soil-borne pathogens can contribute to seed mortality in this way, but we don’t know how important different parts of their lifecycle are in creating Janzen-Connell patterns. To determine the role of soil-borne pathogens in the development of Janzen-Connell patterns, we constructed a simulation model to examine how tree and pathogen characteristics affect plant spatial patterns. Under specific combinations of tree and pathogen characteristics, we found that pathogens could create Janzen-Connell patterns. The most important parameters were how far trees dispersed their seeds, and how many seeds a tree produced in a year. These characteristics determined how much of an impact the pathogens were able to have on the tree population because they rely on the density of seeds to determine how far they can spread and how many spores they will produce.

Urbanization is increasing at a dramatic rate as the human population increases. While it is well-known that urbanization tends to decrease species diversity (i.e., biotic homogenization), it is not known how urbanization affects the frequency and efficiency of species interactions. Seed dispersal is a plant-animal interaction that depends on disperser feeding rate, disperser diversity, probability of seed dispersal and germination. How these factors are affected by urbanization however is unknown. In this study, we evaluate how urbanization alters these factors. Urban sites had 2x higher feeding rate and 3x higher number of disperser species. The probability of seed dispersal however was the same between natural and urban sites. Moreover, the probability of germination after dispersal was 20% lower in urban sites, leading to overall negative effects of urbanization on T. radicans seed dispersal. In this study we demonstrated that urbanization can affect species diversity, as well as their ecological functions.

A series of experiments was conducted to: 1) investigate how feeding cattle with different amounts of different-sized seeds affects seed passage rate through the digestive tract, and the germinability of passed seeds; 2) examine how the location of seeds in dungpats of different thicknesses influences seedling emergence , development, and survival in cattle dungpats; and 3) characterize seedling emergence in naturally and artificially deposited cattle dungpats . Three perennial , cool-season grasses, bluebunch wheatgrass [Psuedoroegneria spicata (Pursh) A. Love], Sandberg bluegrass (Poa secunda Presl.), and 'Hycrest' crested wheatgrass [Agropyron desertorum (Fisch. ex Link) X A. cristatum (L.) Gaert.], were used as representative revegetation species for the Intermountain West region. When cattle were fed 60,000, 30,000, 15,000, and 7,500 seeds of bluebunch wheatgrass and Sandberg bluegrass, the recovery of passed seeds for both species declined as seed feeding levels decreased from 60,000 to 7,500 seeds per animal and as time after seed ingestion increased from 1 to 4 days. Sandberg bluegrass seeds had greater germinability than bluebunch wheatgrass seeds at all seed feeding levels and collection dates. In complementary greenhouse studies, artificially prepared cattle dungpats (20 cm diameter) with different thicknesses (1, 2, and 4 cm) were placed on a sandy loam soil (initially at field capacity) in large plastic containers. Pre-germinated seeds of blue bunch wheatgrass, Sandberg bluegrass, and/or Hycrest crested wheatgrass were planted separately in the center and periphery of dungpats at heights (from bottom of dungpats) of 0.5 cm for 1-cm-thick dungpats, 0.5 and 1.5 cm for 2-cm-thick dungpats , and 0.5, 2.0, and 3.5 cm for 4-cm -thick dungpats. Half of the dungpat treatments received no supplemental water while the other half received additional water simulating a wet spring . After 60 days, seedling emergence, development , and survival for all species were greatest at the 0.5 cm planting height , regardless of dungpat thickness , and greatest in 1 cm-thick dungpats , regardless of planting height. Seedling emergence , development , and survival were greatest for Hycrest crested wheatgrass, followed by bluebunch wheatgrass and Sandberg bluegrass. In a field study, cattle dung containing passed seeds of blue bunch wheatgrass, Hycrest crested wheatgrass, and Sandberg bluegrass was formed into artificial dungpats (2 kg in mass) with thicknesses of 1, 2, and 4 cm, and respective diameters of 40, 28, and 20 cm, and deposited on bare soil. Cattle also deposited natural dungpats varying in mass, thickness, and diameter. Seedling emergence for all species decreased as artificial dungpat thickness increased from 1 to 4 cm, and was lowest in natural dungpats. Seedling emergence for all dungpat types was greatest for Hycrest crested wheatgrass, followed by Sandberg bluegrass and bluebunch wheatgrass. These studies indicate that: 1) cattle should be fed about 60,000 seeds ( of these grass species) per animal to pass sufficient germinable seed to establish at least one seedling in a dungpat; and 2) seedling emergence, development, and survival in cattle dungpats are greatly influenced by plant species (seeds) ingested, thickness of dungpats, seed location in dungpats, and moisture content of the soil underlying dungpats.

The rate of global urbanization is increasing rapidly as the human population expands, leading to species loss and biotic homogenization. Less studied, however, is the effect of urbanization on the frequency and efficiency of species interactions. Animal-based seed dispersal interactions may be especially sensitive to urbanization because they depend on several factors: 1) the rate of seed dispersal interactions (feeding), 2) diversity of disperser species, 3) the probability of seed dispersal and 4) the probability of germination after seed dispersal. However, how urbanization disrupts species interactions, including seed-dispersal, is still poorly known. In this study, we evaluate differences in the frequency and efficiency of seed dispersal between urban and natural sites using Eastern Poison Ivy (Toxicodendron radicans) as the focal species. Individual T. radicans lianas within natural and urban sites were observed in twelve-minute intervals (total 185.8 hours) at urban and natural sites during which the number and identity of feeding avian species was recorded. A total of 9500 fruits between natural and urban sites were marked with a UV fluorescent dye. Undispersed marked fruits were recovered via seed traps to estimate probability of dispersal. Defecated fruits were collected from natural and urban sites to evaluate germination efficiency after dispersal. Feeding rate was twice as high in urban compared to natural sites (P=0.007). Additionally, seed disperser diversity was on average twice as high in urban sites and species composition was significantly different between natural and urban sites. However, probability of seed dispersal was not significantly different between urban and natural sites (P=0.3). Interestingly, germination rate was 20% higher in defecated seeds collected from natural sites compared to defecated seeds from urban sites (P=0.005). Our results suggest that while T. radicans attracts a higher number and greater diversity of seed dispersers in urban areas, overall dispersal success is the same or even greater at natural sites, as seeds have a higher chance of germinating after being consumed by dispersers at natural compared to urban sites. Species composition differences between sites may play an important role in germinability of seeds; differences in species’ feeding strategies result in differences in their ability to scarify seeds in their digestive systems, a necessary step for seeds that rely on animal seed dispersers. Urbanization can thus negatively affect seed dispersal interactions by altering the composition of disperser species. Other animal-based interactions may be similarly affected by urbanization, and thus we emphasize the need for further studies.

No description available.