Eight study sites were established in mid-elevation, south aspect, mixed-oak forests in the Ridge and Valley and Allegheny Mountain physiographic provinces of Southwestern Virginia and West Virginia to address questions concerning the variability in species composition, richness, and relative abundance of vascular plant species in those communities. All forest strata were sampled using a nested plot design. Variability in species richness and species composition was found to be high. Total species richness values ranged from 84 to 273, and Sorrenson's Coefficient of Similarity index values indicated that approximately 46, 38, and 51 percent of the species in the overstory, mid-story, and herb stratum were the same among sites, respectively. However, despite differences in composition and richness, K-S tests revealed significant differences in the distribution of ranked relative abundance only in the mid-story at two sites. Differences did occur in the relative abundance of twelve growth form categories. While tree seedlings and perennial herbs dominated, on average, woody vines and fern species represented substantial coverage on sites in the Allegheny Mountains. Correlations among forest strata were weak. The greatest amount of variation in species richness was attributiable to the standard deviation of a forest site quality index (FSQI), which was thought to represent the variation in microtopography across each site. The lack of correlation and high variability in plant species richness and composition, despite similarities in topographic characteristics, reinforce the inherent weaknesses involved with using the chronosequence approach to studying ecological responses in the Southern Appalachian mixed-oak region. Future remeasurement and long term monitoring of these study sites, following the implementation of silvicultural manipulations, will provide the information needed to make inference on the effects of forest management practices on Southern Appalachian mixed-oak forests. / Master of Science

Much research debates whether properties of ecological networks such as nestedness and connectance stabilise biological communities while ignoring key behavioural aspects of organisms within these networks. Here, we computationally assess how adaptive foraging (AF) behaviour interacts with network architecture to determine the stability of plant-pollinator networks. We find that AF reverses negative effects of nestedness and positive effects of connectance on the stability of the networks by partitioning the niches among species within guilds. This behaviour enables generalist pollinators to preferentially forage on the most specialised of their plant partners which increases the pollination services to specialist plants and cedes the resources of generalist plants to specialist pollinators. We corroborate these behavioural preferences with intensive field observations of bee foraging. Our results show that incorporating key organismal behaviours with well-known biological mechanisms such as consumer-resource interactions into the analysis of ecological networks may greatly improve our understanding of complex ecosystems.

A adaptação e a diversificação em sistemas multiespecíficos são crescentemente reconhecidas como processos relevantes para a compreensão da biodiversidade. Nosso objetivo foi investigar como a seleção natural relacionada a interações ecológicas influencia a estrutura, dinâmica e diversificação de assembleias mutualistas. Primeiro, modelamos como mutualismo e competição intraespecífica geram regimes seletivos antagônicos que definem padrões de diversificação. Nossos modelos preveem que em mutualismos de baixa intimidade, nos quais cada organismo têm muitos parceiros individuais, fenótipos extremos têm interações mutualísticas desajustadas em relação à complementaridade de traços, contrabalanceando efeitos diversificadores da competição intraespecífica e restringindo a especiação. Em sistemas de alta intimidade, nos quais mutualismos têm maior impacto adaptativo e cada organismo têm poucos parceiros, tal seleção estabilizadora imposta por mutualismos é reduzida, favorecendo a diversificação. Entretanto, mutualismos de baixa intimidade são mais ricos que mutualismos íntimos na natureza. Sob baixa intimidade de interações, adições de espécies não-aparentadas envolvidas em dinâmicas de convergência constituem explicação plausível para essa discrepância. Em sistemas de alta intimidade, restrições a adições de espécies impostas por histórias coevolutivas estreitamente relacionadas poderiam explicar menores riquezas, apesar do maior potencial de diversificação adaptativa. Em segundo lugar, avaliamos se reconfigurações adaptativas das interações ecológicas podem explicar a variação estrutural de redes mutualistas. Usando um modelo eco-evolutivo, mostramos que a seleção favorecendo trocas de mutualistas e maximizando a abundância das espécies altera propriedades das redes, aumentando seu aninhamento e diminuindo sua estabilidade. Nossos modelos superestimaram o aninhamento em mutualismos de alta intimidade, possivelmente porque não consideramos ligações proibidas impostas por morfologia ou fenologia. Entretanto, as redes simuladas reproduzem aninhamento e modularidade de mutualismos de baixa intimidade, cujas interações são mais flexíveis. Sob competição por mutualistas, as reconfigurações da rede continuam em um dinâmica sem fim, mesmo quando estrutura e a estabilidade atingem níveis assintóticos, o que pode explicar a variação empírica de interações em redes com estruturas temporalmente constantes. Em um terceiro estudo, modelamos como diferentes modos de especiação modificam propriedades de redes mutualistas. Se a especiação resulta em expansão do nicho e as espécies emergentes tornarem-se mais conectadas, o aninhamento aumenta e a modularidade diminui, frequentemente resultando em redes instáveis. Se a especiação causar retração do nicho e as espécies emergentes tornarem-se menos conectadas, aninhamento e modularidade aumentam, promovendo estabilidade. Diferentes regras de sobreposição de nicho entre espécies emergentes não alteraram esses resultados. Assim, retrações de nicho via divergência adaptativa, como deslocamentos de caracteres na especiação simpátrica, devem gerar espécies incorporáveis às redes mutualistas sem desestabilização. Entretanto, expansões de nicho via adaptações a recursos complementares em alopatria devem desestabilizar as redes quando do contato secundário. Efeitos potencialmente amplos de um único evento de especiação mostram que estudos relacionando diversificação e dinâmica são relevantes para o debate sobre complexidade e estabilidade de redes ecológicas. Concluímos que a compreensão mecanística sobre as origens e a manutenção da biodiversidade depende da integração de teorias ecológicas e evolutivas com base em dados empíricos, como fizemos aqui ao modelar dinâmicas adaptativas de interações ecológicas usando informações sobre a organização e história natural de assembleias mutualistas / Adaptation and diversification in species-rich systems are increasingly recognized as relevant processes to improve our understanding on biodiversity. Our aim was to investigate how natural selection related to ecological interactions shapes the structure, dynamics and diversification of mutualistic assemblages. First, we modeled how mutualism and intraspecific competition generate antagonistic selective regimes that define patterns of diversification. Ours models predict that in low intimacy mutualisms, in which each organism has various individual partners, extreme phenotypes experience trait mismatches in mutualistic interactions that oppose the diversifying effects of intraspecific competition and constrain speciation. In high intimacy systems, in which mutualistic interactions have a higher impact on fitness and each organism has fewer partners, such stabilizing selection is reduced, favoring diversification. However, low intimacy mutualisms are richer than high intimacy mutualisms in nature. Under low interaction intimacy, additions of non-related species involved in trait convergence dynamics are a plausible explanation for such a discrepancy. In high intimacy systems, restrictions to species additions imposed by tight coevolutionary histories could explain lower richnesses despite of a higher potential for adaptive diversification. In a subsequent study, we evaluated whether the adaptive rewiring of ecological interactions explain the structural variation of mutualistic networks. Using an eco-evolutionary model, we show that selection favoring continuous interaction switching that maximizes species abundances changes network properties, increasing nestedness and decreasing stability. Our models overestimated nestedness in high intimacy mutualisms, probably because we did not consider forbidden links imposed by morphology or phenology. However, simulated networks reproduce nestedness and modularity of low intimacy mutualism, in which interactions are more flexible. Under competition for mutualists, rewires continue in an endless dynamics, even when the structure and stability reach asymptotic levels at the network level, which could explain the empirical variation of interactions in networks showing temporally constant structures. In a third study, we modeled effects of different modes of speciation on mutualistic network properties. If speciation results in niche width expansion and emerging species become more connected, nestedness increases and modularity decreases, often resulting in unstable networks. If speciation causes niche width retractions and emerging species become less connected, both nestedness and modularity increase, promoting stability. Different rules of niche overlap between emerging rules did not change these results. Therefore, niche retractions via adaptive divergence, such as character displacement in sympatric speciation, can generate species that will enter local networks without destabilizing them. However, niche width expansions due to adaptation to additional resources in allopatry should destabilize networks if secondary contact between emerging species occur. High magnitude potential effects of a single speciation event show that studies relating diversification and dynamics are relevant to the debate on complexity and stability of ecological networks. We concluded that the mechanistic understanding of biodiversity origins and maintenance relies on the integration between ecological and evolutionary theories based on empirical data, as wed did here by modeling the adaptive dynamics of ecological interactions using information on the structure and natural history of mutualistic assemblages

The foundation Stora Sköndal is currently planning a city development programme with a focus on creation of a modern, socially sustainable urban district. The programme is called “Framtidens Stora Sköndal”. With close collaboration with the city planning office in Stockholm and with the aim to contribute to the goals that the City of Stockholm has set for a development of a coherent and socially sustainable city, the foundation aims to build “an inclusive area, characterized by empathy and an open-minded attitude” where people from different backgrounds, different origins, with different economical, physical, and psychological abilities can meet and live together. The programme plan encompasses new housing for approximately 10,000 additional dwellers and thousands of new workplaces. It also includes for example, six character areas and six principles for urban planning that have been developed for the programme to support the goals of creating a socially sustainable urban district of Sköndal. The programme is planned to be implemented by 2035 hence, within this study it will not be possible to draw any conclusions on the final result. Rather, this study is a descriptive study that discusses theory, visions, programme documents and the process behind the programme and the different actors involved. The study has showed that the programme for Framtidens Stora Sköndal has a potential to deliver at least some part of the visions and goals they aiming at. However, the process and the implantation of a socially sustainable district can meet challenges along the way. The individuals have been shown to play an important role in the development and implementation of the programme. Furthermore, the steering effects of economy seems to trump even strong ideas and visions. Politics are other factors that have been showed being a game changer.