There is renewed interest in cotton performance grown using various row spacings and plantings patterns in the Midsouth. Cotton seed size has been reduced compared to sixty years ago. Planting smaller seeds is concerning due to having less energy for emergence as well as complicating the ginning process. Two row spacings, two planting patterns, and two cotton varieties were evaluated over eight site years from 2019-2020. The solid planting pattern produced a higher yield on a land area basis. In addition, two varieties, each with three seed counts, were planted at three seeding rates and evaluated over six site years from 2019-2020. Greater seedcotton yields were observed from larger seed sizes and higher seeding rates. Row spacing had no impact on yield but depending on input cost, a 2x1 skip pattern could be beneficial. Also, higher seeding rates and larger seeds maximized yields.

Thesis (MSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Invasive alien plants have had diverse ecological and social impacts on recipient ecosystems and are a major problem for land managers. Successful management demands an understanding of the ecology of invading taxa. The invasive status and impacts are documented for Prosopis populations in South Africa. However, unresolved taxonomic issues, the extent of hybridization, the applicability of morphology as a species identification approach, and the role that some traits plays in the invasion success have not been studied. This creates a gap that hinders implementation of effective management policies. In this thesis I use a phylogenetic approach to determine the taxonomic make-up of invasive Prosopis populations in South Africa (Chapter 2) and compare the results to morphological identification (Chapter 3). I also look at seedling growth rates in the context of variation in genome size and seed size (Chapter 4). Almost all regions invaded by Prosopis are characterized by taxonomic uncertainty exacerbated by the ease of inter-specific hybridization. In Chapter 2 I aim to resolve taxonomic issues of invasive Prosopis populations in South Africa using a phylogenetic approach. In addition, I aim to unravel the extent of hybridization and the species involved in South Africa. Here, I found that Prosopis populations in South Africa comprise both reported and previously unreported species, indicating a need for a reassessment of the identity of invasive taxa. Hybridization is prevalent and all confirmed species are involved. These findings call for a rethink of legislation and management approaches, e.g. the selection of classical biological control agents. Overall the extent of hybridization indicates that Prosopis species in South Africa comprise a freely inter-breeding population typical of a syngameon. Proper morphological identification of invasive species is crucial for ecological studies and management of invasions. In Chapter 3, I use the total evidence approach to assess whether morphological approaches for identification are adequate for identifying Prosopis species in South Africa. I found that Prosopis taxa in South Africa cannot be reliably distinguished using existing morphological keys. This is likely due mainly to the proliferation of hybrids with a diverse morphology. Therefore, molecular tools are crucial for confirming any morphological identities and for determining the presence of any unreported species. Genome size and seed size have been reported to be associated with invasiveness in a number of plant groups, but not often in a system with multiple hybrids like Prosopis. In Chapter 4, I first investigate the relationship between genome size and seed size in invasive populations of Prosopis spp. in South Africa and secondly I investigate how genome and seed sizes influence germination and early growth. Here I found that genome size loses its distinctness, being diluted in hybridizing populations, but can still be used to assess hybridization events themselves. Large seed size seems to be important for invasiveness as it positively influences germination and early growth. This thesis confirms the taxonomic conundrum of Prosopis species in invasive ranges. This coupled with inadequacy of morphological identification calls for a global study involving native and invasive range taxa to clarify the existing confusions. In view of the presence of unreported Prosopis species in South Africa and extensive hybridization, a rethink of the current legislation and control is needed. / AFRIKAANSE OPSOMMING: Uitheemse indringer plante het grootskaalse ekologiese en sosiale impakte op die ekosisteme wat hulle indring en stel 'n groot uitdaging vir bestuurders van natuurlike hulpbronne. Suksesvolle bestuur en bestryding van indringer plante verg deeglike kennis oor hulle ekologie. Die indringer status en impakte van Prosopis populasies in Suid Afrika is reeds voorheen beskryf. Nieteenstaande, die problematiese taksonomie, die omvang van hibridisasie, die waarde van morfologiese identifikasie, en die rol wat sekere eienskappe speel in die sukses van hierdie groep is nog nie bestudeer nie. Daar is dus 'n gaping in kennis wat die effektiewe beheer van die groep in Suid Afrika belemmer. In hierdie tesis pas ek 'n filogenetiese benadering toe om die taksonomiese verwantskappe van Prosopis populasies in Suid Afrika te bepaal (Hoofstuk 2) en vergelyk my resultate met morfologiese identifikasie sleutels (Hoofstuk 3). Ek ondersoek ook saailing groei tempos in die konteks van variasie in genoom en saad groote in die groep (Hoofstuk 4). Bykans alle areas in Suid Afrika waar Prosopis voorkom word gekenmerk deur taksonomiese onsekerheid, verder bemoeilik deur die gemak waarmee spesies vrylik hibridiseer. Ek vind dat beide bekende en voorheen-onbeskryfde Prosopis spesies in Suid Afrika aangetref word en beklemtoon die behoefte om die identiteit van spesies in die land te hersien. Hibridisasie kom algemeen voor tussen alle spesies teenwoordig in Suid Afrika. Hierdie bevindinge beklemtoon dat wetgewing en beheermaatreêls hersiening benodig, byvoorbeeld in die toepassing van biologiese beheer. In samevatting kom dit voor asof hibridisasie gelei het tot 'n vrytelende Prosopis groep in Suid Afrika, tipies van 'n singameon. Ordentlike morfologiese identifikasie van indringer spesies is belangrik in enige ekologiese studie en die implementering van doeltreffende beheermaatreëls. In Hoofstuk 3 gebruik ek ʼn ‘totale bewys’ benadering om vas te stel of morfologiese eienskappe alleenlik genoegsaam is om Prosopis spesies in Suid Afrika korrek te kan identifiseer. Ek vind dat spesies nie geloofwaardig geïdentifiseer kan word nie, heel moontlik as gevolg van wydverspreide hibridisasie tussen alle spesies teenwoordig in die land. Genoom en saad groote is voorheen geassosieer met die indringer aard van verskeie plant groepe. In Hoofstuk 4 ondersoek ek die verwantskap tussen genoom en saad groote. Tweedens bepaal ek die invloed van genoom en saad groote op ontkieming en vroeë groei eienskappe van Prosopis. My bevindinge toon dat, terwyl die kenmerklikheid van genoom groote verloor word as gevolg van hibridisasie, dit steeds hibridisasie gebeurtenisse per se kan identifiseer. Groot sade het ook ʼn positiewe invloed op die ontkieming en vroeë groei eienskappe van Prosopis. Die tesis bevestig die taksonomiese onduidelikheid van indringer Prosopis taksa in Suid Afrika. Tesame met die onakkuraatheid van morfologiese sleutels beklemtoon my bevindinge die behoefte vir ʼn dringende wêreldwye studie op indringer en inheemse populasies van Prosopis om taksonomiese onsekerhede op te klaar. Die identifikasie van nuwe spesies in Suid Afrika beklemtoon ook die behoefte om huidige wetgewing en beheer van die groep in die land te hersien.

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.

Master of Science / Genetics Interdepartmental Program / Eduard D. Akhunov / The CRISPR/Cas9-based genome editing system holds a great promise to accelerate wheat improvement by helping us to understand the molecular basis of agronomic traits and providing means to modify genes controlling these traits. CRISPR/Cas9 is based on a synthetic guide-RNA (gRNA) that can guide Cas9 nuclease to specific targets in the genome and create double strand breaks (DSB). The DSB are repaired through the error-prone non-homologous end joining process causing insertions or deletions that may result in loss-of-function mutations. Here, we have developed an effective wheat genome editing pipeline. We used next-generation sequencing (NGS) data to estimate genome editing efficiency of many gRNAs using the wheat protoplast assay and choose the most efficient gRNAs for plant transformation. We successfully applied this pipeline to five wheat orthologs of the rice yield component genes that have been identified previously. We obtained edited plants for all these genes and validated the effect of the mutations in TaGW7 on wheat traits, which showed trends similar to those in rice. These results suggest that transferring discoveries made in rice to improve wheat is a feasible and effective strategy to accelerate breeding.

Soil seed banks are important to the maintenance and restoration of floras. Extant seed banks exhibit unique characteristics with regard to the distribution of seed size and seed density. Seeds were recovered from the Upper Pennsylvanian Wise Formation in southwest Virginia. Structurally preserved seeds were also examined from coal balls of the Pennsylvanian Pottsville and Allegheny Groups, Ohio. The size distribution of the seeds from the Wise Formation is similar to that of structurally preserved seeds of the Upper Pennsylvanian Pottsville and Allegheny Group coal balls. In contrast, the seed size distributions in extant wetland, grassland, woodland and forest habitats are significantly narrower than that of seeds from the Pennsylvanian seed banks. Larger seeds are less dependent on light for germination, and aid in seedling establishment more than smaller seeds, especially in dense stable forests where disturbance events are rare. Large seed size may contribute to increased seed longevity, which reduces the effect of environmental variability on seed germination and development. The significantly larger size of the Palaeozoic seeds may have imparted an advantage for seedling establishment in the dense Palaeozoic forests. The preponderance of large seeds may be a result of the absence of large seed predators (e.g. herbivorous tetrapods), and may have been an evolutionary strategy to minimize damage to the embryo from a predator population dominated by small invertebrates with chewing or sucking mouthparts. The estimated seed density of 192 seeds/m2 in the Palaeozoic seed bank falls within the range of modern seed banks, but at the lower end of modern seed bank densities in a variety of habitats.

No description available.

Soybeans within a specific seed size range are often preferred for the manufacture of specialty soy products. This study examined the influence of row spacing and seeding rate on seed yield, average seed size, and seed size uniformity of Camp (small seeded) and V71-370 (large seeded) soybean cultivars [Glycine max (L.) Merr.]. Experiments were conducted in 1992 and 1993 at Kentland Farm near Blacksburg, Virginia. Row widths of 38 and 76 cm and seeding rates of 125, 250, 500, and 750 thousand seeds ha⁻¹ were used. Averaged over treatments, 38-cm row spacings yielded higher than 76-cm row spacing by 11.6%. Additionally, each increase in seeding rate resulted in increased yield up to 500,000 seeds ha and then leveled off. Yield of useful seed of Camp (total yield multiplied by the proportion of seed between 4.8 and 5.6 mm in diameter) was maximized at narrow row spacings and 500,000 seeds ha⁻¹. Neither row spacing nor seeding rate influenced V71-370 yield of usable seed (larger than 7.9 mm). Averaged over years and cultivars, soybean seed size was not influenced by row spacings or seeding rates. However, in 1993, smaller Camp seed was favored by narrow rows and low seeding rate. Seed size uniformity, as determined by analysis of variance of individual seed weights was, in general, not influenced by row spacing or seeding rates. In a separate investigation in 1992, heritabilities were estimated by two methods using plot data from two replications of lines from crosses of Camp with Jizuka, MD87L-0198, and Stafford soybean cultivars. Heritabilities based on F₃ progeny means regressed on F₂ parental means ranged from 24% to 41% and were lower than the corresponding heritability estimates based on analysis of variance which ranged from 43% to 83%. Correlations of seed size with other agronomic traits were generally low. Although low in magnitude, significant positive correlations of seed size with yield in some crosses might hinder progress of breeders when selecting for small-seeded, high yielding cultivars. / Ph. D.

A presente dissertação teve como objetivo investigar se padrões presentes nas comunidades arbóreas adultas podem ser gerados por diferenças em aspectos relacionados ao nicho de regeneração das espécies. Nosso modelo de estudo foram duas florestas de restinga localizadas na Ilha do Cardoso, litoral sul do estado de São Paulo. A floresta de restinga alta (RA) é uma formação geologicamente mais antiga e possui dossel mais fechado que a floresta de restinga baixa (RB). No Capítulo 1, investigamos se as inversões de abundância das árvores adultas entre RA e RB podem ser geradas devido ao desempenho diferenciado destas espécies ainda na fase de plântula, devido à atuação do filtro ambiental luminosidade. Hipotetizamos que as espécies apresentem pior desempenho no estágio de plântula na floresta em que são menos abundantes como adultos, devido a uma demanda conflitante entre crescimento e sobrevivência. Esperávamos também que a mortalidade por patógenos fosse a principal causa de mortalidade das plântulas na floresta mais sombreada. Realizamos um experimento manipulativo em campo com seis espécies arbóreas, no qual plântulas com um mês após a germinação foram transplantadas nas duas florestas e no viveiro. Acompanhamos o desempenho destas plântulas durante nove meses. Não houve diferenças no desempenho das espécies entre as duas florestas estudadas, exceto na sobrevivência de Clusia criuva (no sentido esperado) e de Tapirira guianensis (sentido oposto ao esperado). Diferente do esperado, a principal causa de mortalidade de todas as espécies foi a herbivoria severa e não foi observado um conflito entre crescimento e sobrevivência. No Capítulo 2 investigamos se as diferenças de tamanho de semente entre as espécies arbóreas zoocóricas podem gerar diferenças nos padrões da comunidade adulta e essas diferenças ocorrem devido à atuação do filtro ambiental da luminosidade ou apenas devido às diferenças de capacidade de dispersão das espécies. Acompanhamos a chuva de sementes das espécies zoocóricas arbóreas durante quatro anos nas duas florestas e verficamos que a capacidade de dispersão ativa está negativamente relacionada ao tamanho de sementes, como é previsto por ambas as hipóteses (filtro ambiental e capacidade dispersão). Além disso, a relação entre a produção média de sementes e o tamanho de sementes apresentou um padrão triangular, de modo que as espécies de sementes grandes apresentam sempre baixas produções. Comparamos os tamanhos médios de sementes e a amplitude de tamanhos de sementes dos indivíduos e espécies estabelecidos como adultos nas duas florestas (DAP>= 5cm). Verificamos que a RA apresenta tamanho médio de semente e amplitude de tamanhos de sementes maiores que a RB. Além disso, a composição florística da RB está aninhada na composição da RA. Assim, hipotetiamos que as diferenças na capacidade de dispersão das espécies, aliadas às diferenças de idade das florestas são responsáveis pela distribuição de tamanho de sementes dos adultos estabelecidos nas duas florestas. Por fim, no capítulo 3, realizamos uma revisão bibliográfica sobre o papel dos microorganismos do solo no nicho de regeneração das espécies arbóreas tropicais. Foram encontrados estudos que abordam apenas a atuação de fungos, seja em interações positivas (fungos micorrízicos) ou negativas (fungos patogênicos). Discutimos os principais fatores e características associadas à mortalidade por patógenos do solo, bem como relações levantadas pelos estudos pioneiros que não foram corroboradas ou testadas / The objective of the current research was to investigate if the existing patterns in the adult tree communities can be generated by differences in the aspect related to the regeneration niche of species. Our model of study were two restinga\'s forests located at the Cardoso Island, on the South coast of São Paulo state. The tall resting forest (TRF) is an older formation, geologically speaking, and it hás closer canopies than the short resting forest (SRF). In the first chapter, we investigated if the abundance inversions of adult trees existing between the TRF and the SRF could be generated due to the differentiated performances of these species at the stage of the seedling, due to the action of the environmental light filter. We assumed as a hypothesis that the species show a worst performance in the stage of seedling in the forest where they are less abundant as adult, due to a trade-off between growth and survival. We expected that the mortality by pathogens was the main cause for the mortality of plants in the more shaded forest. We achieved a manipulative experiment in field with six tree species, in which one-month-old seedlings after germination were transplanted in the two forests and in the nursery. We followed the performance of the species in the two studied forests for nine months. There were no differences in the performance of the two species, except the survival of the Clusia criuva (in the expected way) and of the Tapirira guianensis (opposite to the expected way).Different from what was expected, the main cause of the mortality of all the species was the severe herbivory, and it was not possible to observe a conflict between the growth and the survival of them. In the second chapter, we investigated if the differences in the size of the seeds among the zoochoric tree species can generate differences in the patterns of the adult community and if those differences occur due to an action of the environment lighting filter or only by the differences of the dispersion capacity of the species. We followed the seed rain of the zoochoric tree species for four years in both forests and we could check that the active dispersion capacity of them is negatively related to the size of the seeds, as it can be predicted by both the hypothesis (environmental filter and dispersion capacity). Besides, the relationship between the average production of seeds and the size of the seeds presented a triangular pattern, as species with big seeds always provide low productions. We compared the seeds average sizes and the range of the seeds sizes of the individual plants and of the adult species in both forests (DAP_> 5 cm. We could verify that the TRF presents average size of seeds and range of the seeds\'s sizes that were bigger than in SRF. Furthermore, the SRF floristic composition is nested in the TRF composition. Therefore, we assumed as a hypothesis that the differences in the dispersal capacity of species, plus the age differences of the forests, are responsible for the distribution of the seeds sizes of the adult plants present in both forests. Finally, in chapter 3, we made a literature review about the role of the soil microorganisms in the specific site of the regeneration of the tropical tree species. We found studies that focus only on the action of the fungi as far in positive interactions (mycorrhizal fungi) as in negative ones (pathogenic fungi). We discussed the main factors and the characteristics associated to the mortality caused by the soil pathogens, as well as the relationship proposed by the pioneer studies which were not confirmed nor tested

It is becoming increasingly important to improve the yield of seed crops to feed an expanding population and, more recently, to cope with additional strains on food-oriented agriculture posed by biofuel production and global climate change. One strategy to increase yield is to increase seed size. However in nature, due to the limited resources of the mother plant, an enlarged seed size is often associated with a concomitant reduction in seed number. Using the model plant Arabidopsis thaliana, a biotechnological approach to increase seed size through the modification of the triploid endosperm or the ovule integuments was shown to be a viable strategy to improve seed yield. Targeted over-expression of the ANT transcription factor specifically within the endosperm significantly increased seed size without negative effects on fertility. Overcoming compromised fertility in arf2 mutants established that ARF2 and the integuments are important factors in determining seed size and yield. To ensure agronomic relevance, both the gross yield and the harvest index (HI, ratio of seed yield to biological yield) were used to assess the impact of traits, such as increased integument size, introduced into Arabidopsis. To uncover novel regulators of seed size and further develop the current understanding of seed development, second-site mutations were induced in the auxin response factor 2 (arf2) mutant, which produces large seeds due to extra cell division in the ovule integuments. The ARABIDOPSIS CRINKLY 4 (ACR4) gene was identified as a suppressor of the arf2 seed phenotype. In arf2-8 acr4 double mutants, an additive effect on cell proliferation was observed, indicating that ACR4 affects the seed coat through a developmental pathway independent of ARF2. Natural variation present in Arabidopsis was used to study seed yield and its components. Considerable variation in seed size, yield and HI was revealed. Significantly, high seed weight was not associated with high yield or high HI. In contrast, high seed number and reduced plant stature were revealed as important components of high yield and yield efficiency. Additionally, ERECTA was identified as a potential ‘Green Revolution’ gene. Seed size in Arabidopsis was shown to be an extremely plastic trait in response to alterations in the post-flowering source-sink ratio, increasing by 35.0 – 66.2% in the ecotypes tested. Furthermore, a difference in seed weight between restricted (high source-sink ratio) and unrestricted (low source-sink ratio) pollinations was first observed remarkably early in seed development. However, reducing seed number by restricting pollination did not substantially alter integument or endosperm development in order to facilitate increased nutrient uptake.

A expansão da floresta sobre o campo, a partir do estabelecimento de araucárias isoladas (nucleação), forma uma paisagem única no planalto sul-brasileiro, sendo que o uso de uma abordagem de metacomunidades pode auxiliar a compreender melhor esse processo. Existem quatro modelos de metacomunidades que explicam a relação entre comunidades locais: dinâmica de manchas, seleção de espécies, efeitos de massa e neutro. Esses modelos possuem diferentes premissas quanto aos processos de nicho e de dispersão que atuam na dinâmica da metacomunidade. No entanto, há uma lacuna entre a teoria e o teste desses modelos em estudos empíricos. Uma forma de testar mais claramente esses modelos é através de uma abordagem funcional. Nesse contexto, o objetivo do trabalho foi avaliar a importância (i) de atributos relacionados às estratégias de dispersão e de crescimento das espécies, (ii) da abundância das espécies no pool regional e (iii) do tamanho da mancha, na organização de comunidades de indivíduos lenhosos juvenis em áreas de nucleação florestal sobre o campo, a fim de compreender quais modelos de metacomunidades melhor explicam esse processo. Para tanto, calculamos o CWM (Community Weighted Mean) e índices de diversidade funcional, considerando a ocorrência (sesFD) e a abundância (sesFDis) das espécies, para tamanho da semente e área foliar específica (SLA), em manchas florestais de distintos tamanhos e na floresta contínua adjacente ao campo, e testamos se as áreas diferem entre si de acordo com o tipo de ambiente. Avaliamos ainda se a abundância relativa das espécies nas áreas de nucleação é determinada pela abundância das mesmas na floresta contínua, através do uso dos modelos de Community Assembly by Trait Selection (CATS). Os resultados foram então comparados com o esperado para cada modelo de metacomunidade. A maior parte dos sítios apresentou índices de diversidade funcional para SLA e tamanho da semente de acordo com o esperado ao acaso. As áreas não diferiram quanto ao CWM para SLA. No entanto, foram observadas diferenças quanto ao CWM para o tamanho da semente, com o favorecimento de espécies com sementes menores em áreas mais abertas, e espécies com sementes maiores em áreas mais sombreadas. De acordo com os modelos CATS, a abundância das espécies no pool regional foi mais importante do que os atributos para a determinação da abundância das mesmas nas comunidades locais. Concluiu-se que o modelo de metacomunidades que melhor explica o processo de nucleação florestal sobre o campo no planalto das araucárias é o modelo de efeitos de massa, o que ressalta a importância da dispersão para a estruturação das comunidades locais. Como a maior parte das espécies lenhosas existentes na área possui dispersão zoocórica, esse resultado indica que a preservação da fauna dispersora é fundamental para a dinâmica desse ecossistema. Com o uso de uma abordagem funcional, em conjunto com os modelos CATS, foi possível testar os quatro modelos de metacomunidades. Assim, o método proposto pode ser aplicado a outros sistemas naturais, auxiliando na compreensão do funcionamento de diferentes metacomunidades. / The forest expansion over the grassland, from the establishment of isolated Araucaria (nucleation) forms a unique landscape in south brazilian plateau, and the use of a metacommunity approach can help to better understand this process. There are four metacommunity models that explain the relationship between local communities: patch-dynamics, species-sorting, mass-effects and neutral. These models have different assumptions about niche processes and dispersion that act in metacommunities dynamics. However, there is a gap between theory and the test of these models in empirical studies. One way to test these models more clearly is through a functional approach. In this context, the objective of this study was to evaluate the importance of (i) attributes related to dispersion and growth species strategies, (ii) species abundance in the regional pool and (iii) patch size, on structuring communities of juvenile woody individuals in forest nucleation areas on the grassland in order to understand which metacommunity model explain this process. Therefore, we calculate the CWM (Community Weighted Mean) and functional diversity indices, considering species occurrence (sesFD) and abundance (sesFDis) for seed size and specific leaf area (SLA), in forest patches of different sizes and in adjacent continuous forest and tested if sites differ according to ambient. Further, we evaluated if species relative abundance in nucleation areas is determined by the abundance in the continuous forest, by the use of Community Assembly by Trait Selection (CATS) models. Then, we compared results with expected for each metacommunity model. Most of sites presented functional diversity values for SLA and seed size as expected by chance. Areas did not differ in CWM to SLA. However, we observed differences for CWM to seed size, favoring species with smaller seeds in more open areas, and species with larger seeds in more shaded areas. According to CATS models, species abundance in regional pool was more important than attributes to determine species abundance in local communities. We concluded that the metacommunity model that best explains forest nucleation on the grassland in Araucaria plateau is the mass-effects model, which emphasizes the importance of dispersion for structuring local communities. As most of existing woody species has zoochorous dispersion, this result indicates that preservation of disperser fauna is essential for ecosystem dynamic. By using a functional approach in combination with CATS models, it was possible to test the four metacommunity models. Thus, the method proposed in this work can be applied to other natural systems, helping understanding different metacommunities operation.