Analysing ecological communities as complex networks of interactions has become an important tool for ecologists. Understanding how these networks change through time, over landscapes, or in response to disturbances is a primary goal of community ecology. The number of interactions and the way in which those interactions organise themselves as individuals, small groups, and the whole community can play an important role in predicting how ecological communities will respond to disturbances. In this thesis, we investigated variation in network structure at several scales both empirically and in a theoretical context. Our first hypothesis was that the structural role of species in a variable system would show little variation, despite high levels of species turnover and a fragmented landscape. In a collaboration with Riikkaa Kaartinen and Tomas Roslin, we studied the distribution of species’ roles at three scales in host-parasitoid networks collected from a fragmented forest in Finland. We found that species’ roles were remarkably consistent through time and in the presence of species turnover. These results suggest that species’ roles may be an intrinsic property of species and may be predictable over spatial and temporal scales. Our second study investigated the structural variation of simulated ecological networks and the relationship between structural variation and whole-network measures of network organization, such as connectance, nestedness, and modularity. We quantified structural variation of networks at three scales, macro-scale, motif-scale, and participation scale. These scales represent whole-network measures (macro-scale), sub-network measures (motifs – small groups of interacting species), and individual measures (motif participation). We compared the variation in these structures to connectance, nestedness, and modularity. We found that at fixed levels of connectance, nestedness, and modularity, the motif profiles of networks and the distribution of species across those profiles showed remarkable dissimilarity. This result suggests that networks displaying similar macro-scale structural measures can be composed of vastly different motif- and participation-scale structures. Together, the work that makes up this thesis suggests that we should give more attention to the meso-scale structures of ecological networks. As the more detailed perspective of motifs can capture additional detail about the structure of empirical networks, and as a result, provide a clearer picture of ecological communities. In addition, we found that the particular species themselves can have a significant impact on the meso-scale structure and, in some cases, may impose strict limitations on what interactions can occur within a community. This has important implications for our understanding of how ecological networks are built and maintained, and thereby for our understanding of the stability and resilience of ecological communities.

Mutualism is an often-complex positive interaction between species, each of which responds independently to varying biotic and abiotic conditions. Temperature is an important factor that can affect species both directly (e.g., physiologically) and indirectly (e.g., via its effects on interactions with consumers, competitors, and mutualists). Although much research has investigated the consequences of temperature for individual organisms, the effects of temperature on the formation, dissolution, and success of species interactions remain minimally understood. The unique ways in which species respond to temperature likely play a role in structuring communities. Environmental heterogeneity, including the thermal environment, can promote coexistence when species exploit resources in different ways, such as by occupying different thermal niches. This dissertation examines the consequences of temperature for participants in an ant-plant protection mutualism, and investigates how the thermal ecology of individual species affects the interaction. Many mutualisms involve multiple species, or interacting guilds. In these mutualisms, species interact with partner species that vary in multiple characteristics. Mutualists are quite sensitive to both partner quantity and partner quality (e.g., their effectiveness at performing a beneficial task). Mutualisms between ants and plants are common across a variety of habitats worldwide, which differ in thermal range, fluctuation, and seasonality. In light of ants’ well-studied and predictable responses to temperature, ant-plant interaction networks provide excellent systems for studying the thermal ecology of mutualisms. In ant-plant protection mutualisms, each of the participants (ants, plants, and enemies) likely differs in its response to temperature. In addition to the direct effects of temperature on ant species, temperature may affect the magnitude of mutualistic interactions among species by affecting the quantity and quality of the reward offered to partners, and the activity of the partners themselves and the plant’s enemies (i.e., herbivores). If herbivores are more thermally tolerant than the mutualistic ant defenders, the consequences for plants may well be severe; however, if herbivores are less thermally tolerant than are the ants, the effects of rising temperatures might be mitigated: although less-effective ants might be more frequent in a warmer world, herbivores would be less abundant there. This dissertation describes the thermal ecology of the participants in a mutualism between the cactus Ferocactus wislizeni and four of its common ant defenders (Forelius pruinosus, Crematogaster opuntiae, Solenopsis aurea, and Solenopsis xyloni) in the extreme environment of the Sonoran Desert, USA. The ants are attracted to extrafloral nectar produced by the plant, and in exchange protect the plants from herbivores, including a common phytophagous cactus bug, Narnia pallidicornis (Hemiptera: Coreidae). Specifically, it investigates how thermal ecology of the individual species affects the interactions among those species. Also, it considers the impact of a tradeoff between behavioral dominance and thermal tolerance among ants.

The dynamics of ecological populations and communities are predominantly governed by three ecological processes, environmental filtering, species interactions and dispersal, and these processes may vary with heterogeneity of the environment. In my PhD research, I investigated how ecologists conceptualize landscape heterogeneity, and how these three ecological processes may vary with spatial and temporal environmental heterogeneity. I conducted my empirical work in Alliaria petiolata, a non-native invasive species in North America, at the Koffler Scientific Reserve at Joker’s Hill in Ontario, Canada. The thesis contains six chapters, where chapters 2 – 5 are structured as stand-alone manuscripts. In chapter 2, I conducted a quantitative review to link the metacommunity concept (which combines the above-mentioned three processes) with different conceptual models of landscape spatial heterogeneity. I found that 78% of metacommunity studies were not explicit about the underlying model of landscape heterogeneity, though there was a significant association between the implied model of landscape heterogeneity and the observed metacommunity model. In chapter 3, I quantified dispersal of Alliaria petiolata, assessed the spatial structure of rosette and adult density, and compared the effects of the different processes on rosette and adult density. Seed dispersal followed a lognormal distribution (μ = 0.01, σ = 0.65). Both adults and rosettes exhibited significant spatial structure up to 2 m. Propagule pressure and interactions among life stages were significant processes shaping rosette density, whereas propagule pressure was the only important process shaping adult density. In chapter 4, I investigated patterns, determinants and demographic consequences of herbivory in A. petiolata. I found that patterns, determinants and demographic consequences of herbivory may vary between life stages and habitat types. One striking finding was that herbivory incidence in A. petiolata may strongly depend on plant life stage, possibly due to a defense–fitness trade off. In chapter 5, I tested whether intra-specific interactions in A. petiolata shift with temporal environmental heterogeneity (seasonality). I found significant negative density-dependent survival in summer and positive density-dependent survival over winter. I suggested that predictions of the stress gradient hypothesis at the intra-specific level are applicable to seasonal variation in environmental stress.

The dynamics of ecological populations and communities are predominantly governed by three ecological processes, environmental filtering, species interactions and dispersal, and these processes may vary with heterogeneity of the environment. In my PhD research, I investigated how ecologists conceptualize landscape heterogeneity, and how these three ecological processes may vary with spatial and temporal environmental heterogeneity. I conducted my empirical work in Alliaria petiolata, a non-native invasive species in North America, at the Koffler Scientific Reserve at Joker’s Hill in Ontario, Canada. The thesis contains six chapters, where chapters 2 – 5 are structured as stand-alone manuscripts. In chapter 2, I conducted a quantitative review to link the metacommunity concept (which combines the above-mentioned three processes) with different conceptual models of landscape spatial heterogeneity. I found that 78% of metacommunity studies were not explicit about the underlying model of landscape heterogeneity, though there was a significant association between the implied model of landscape heterogeneity and the observed metacommunity model. In chapter 3, I quantified dispersal of Alliaria petiolata, assessed the spatial structure of rosette and adult density, and compared the effects of the different processes on rosette and adult density. Seed dispersal followed a lognormal distribution (μ = 0.01, σ = 0.65). Both adults and rosettes exhibited significant spatial structure up to 2 m. Propagule pressure and interactions among life stages were significant processes shaping rosette density, whereas propagule pressure was the only important process shaping adult density. In chapter 4, I investigated patterns, determinants and demographic consequences of herbivory in A. petiolata. I found that patterns, determinants and demographic consequences of herbivory may vary between life stages and habitat types. One striking finding was that herbivory incidence in A. petiolata may strongly depend on plant life stage, possibly due to a defense–fitness trade off. In chapter 5, I tested whether intra-specific interactions in A. petiolata shift with temporal environmental heterogeneity (seasonality). I found significant negative density-dependent survival in summer and positive density-dependent survival over winter. I suggested that predictions of the stress gradient hypothesis at the intra-specific level are applicable to seasonal variation in environmental stress.

O conhecimento das interações entre Brevipalpus phoenicis (Geijskes), outros ácaros fitófagos ou predadores e as plantas de cafeeiro ainda são insuficientes para se poder elaborar um programa adequado de manejo da cultura, para tentar solucionar os problemas causados pela mancha anular. Apesar da importância do problema, pouco se sabe sobre a diversidade de ácaros, assim como a dinâmica populacional do ácaro B. phoenicis e seus inimigos naturais na cultura cafeeira, bem como nas diversas cultivares comercialmente exploradas. As informações sobre o impacto de agroquímicos nas populações de ácaros em cafeeiro são praticamente inexistentes. Contudo, sabe-se que alguns inseticidas ou fungicidas podem afetar a população de ácaros predadores podendo favorecer o aumento populacional de ácaros pragas. Ao caracterizar a diversidade de ácaros em duas importantes regiões produtoras (Jeriquara e Garça), constatou-se que em Jeriquara a diversidade foi superior ao encontrado em Garça. Foram coletados no total 13.052 ácaros nos dois locais estudados, sendo 7.155 em Jeriquara e 5.897 em Garça. De um total de 108 espécies encontradas, 45 espécies foram observadas em ambos os locais avaliados, que apresentaram similaridade de 56%. Os predadores mais freqüentes nas folhas foram Euseius citrifolius Denmark & Muma, E. concordis (Chant) e Agistemus brasiliensis Matioli, Ueckermann & Oliveira. Foram observadas correlações significativas a 0,05% (Pearson) entre as populações E. concordis e B. phoenicis; Zetzellia malvinae Matioli, Ueckermann & Oliveira e B. phoenicis; E. concordis e A. brasiliensis; entre outras. Em relação à diversidade em diferentes cultivares de cafeeiro (Coffea canephora cv Apoatã e de C. arabica cultivares Mundo Novo, Icatu Vermelho, Icatu Amarelo e Catuaí Amarelo) realizado em Garça, verificou-se que a maior riqueza de espécies e o maior número de indivíduos na superfície das folhas foram observados para Apoatã. A cultivar Icatu Vermelho foi a que apresentou maior uniformidade na distribuição das espécies de ácaros e Apoatã a que apresentou menor uniformidade. Em relação à preferência hospedeira, B. phoenicis foi encontrado em maior abundância na cultivar Apoatã, representando 61% de todos os indivíduos. E. citrifolius ocorreu em maior número na cultivar Mundo Novo e E. concordis na Apoatã. A. brasiliensis ocorreu em maior quantidade na cultivar Icatu Vermelho e Z. malvinae ocorreu sem diferença estatística em todas as cultivares. Em relação aos efeitos de pesticidas sobre a diversidade de ácaros, constatou-se que no tratamento com triadimenol + disulfoton apresentou a menor , enquanto que no deltametrina + triazophos a maior. B. phoenicis apresentou redução no número de indivíduos no tratamento com aldicarb e um aumento de cerca de duas vezes nos tratamentos com triadimenol + disulfoton e no thiamethoxam. Os tratamentos que apresentaram as maiores semelhanças na composição das espécies foram: testemunha e cartap, e thiamethoxam e ethion; e os tratamentos de menor similiaridade foram: testemunha e aldicarb, aldicarb e cartap, e aldicarb e deltametrina + triazophos. Reduções significativas na população de A. brasiliensis nos tratamentos com aldicarb e thiamethoxam e de E. citrifolius no tratamento com cartap foram detectadas. / The knowledge on the interactions among Brevipalpus phoenicis (Geijskes), other phytophagous or predaceous mites and coffee plants is still insufficient to establish an adequate management program for this crop, in order to minimize the problems caused by coffee ringspot virus (CoRSV), transmitted by B. phoenicis. In spite of the problem, little is known on the diversity of mites, as well as on the population dynamics of B. phoenicis and its natural enemies on coffee plants of several important commercial cultivars. Information on the impact of agrochemicals on the population of mites on coffee plantations are practically inexistent. However, it is known that some insecticides and fungicides can affect the population of predaceous mites inducing pest mite population increases. Characterizing the diversity of mites on two important coffee-producing areas of the state of São Paulo (Jeriquara and Garça), it was observed that the diversity of mites was higher in Jeriquara county than in Garça. A total of 13,052 mites was collected in both studied areas, of which 7,155 in Jeriquara and 5,897 in Garça. Of the total of 108 species identified in this study, 45 species were observed in both localities (Garça an Jeriquara), which presented 56% of similarity. The most frequent predaceous mites on leaves were Euseius concordis (Chant), E. citrifolius Denmark & Muma and Agistemus brasiliensis Matioli, Ueckermann & Oliveira, among others. The study on the diversity of mites in different coffee cultivars (Coffea canephora cv. ‘Apoat㒠and C. arabica cv. ‘Mundo Novo’, ‘Icatu Vermelho’, ‘Icatu Amarelo’ and ‘Catuai Amarelo’), carried out in Garça, showed the highest species richness and the highest number of specimens for the leaf surface of ‘Apoatã’. ‘Icatu Vermelho’ was the cultivar which presented the highest uniformity of distribution of mite species and ‘Apoat㒠was the cultivar with the lowest uniformity. The species B. phoenicis was found in higher abundance in ‘Apoatã’, representing 61% of all specimens collected. E. citrifolius occurred in higher number on the cultivar ‘Mundo Novo’ and E. concordis in ‘Apoatã’. The stigmaeid mite A. brasiliensis occurred in higher number on the cultivar ‘Icatu Vermelho’ and Z. malvinae was present in similar populations on all coffee cultivars. The study on the effect of pesticides on the mite diversity, showed the lowest diversity for the treatment with triadimenol + dissulfoton, and the highest diversity was observed for treatment with deltamethrin + triazophos. B. phoenicis presented population reduction for the treatments aldicarb, but an increase of around two times for treatments with triadimenol + disulfoton and with thiamethoxam. The treatments with the highest similarities in species composition were: cartap and control (without pesticide), and thiamethoxam and ethion; and the treatments with the lowest similarities were: control and aldicarb, aldicarb and cartap, and aldicarb and deltamethrin + triazophos. A significant reduction in A. brasiliensis population was detected for the treatments with aldicarb and thiamethoxam. E. citrifolius population was affected significantly by cartap.

Ecological systems are inherently dynamic, and a primary way in which they are dynamic is through time. Individual organisms, populations, communities, species interactions, and ecosystem functions all follow a temporal progression from the past, to the present, and into the future. This temporal progression can occur over the course of minutes, hours, days, weeks, months, years, decades, or various other timescales. In this sense, temporal dynamics are an intrinsic property of all biological systems. In fact, one of the most prominent signals of recent global climate change is the significant change in the timing of biological events for a diversity of organisms. In light of this widespread pattern, there is a renewed interest in understanding the multifaceted importance of time in ecology. In this dissertation, I investigate the temporal ecology of a subalpine ecosystem, specifically focusing on flowering plant communities and plant-pollinator interactions. I examine the temporal dynamics of this system over multiple decades in response to ongoing climate change as well as over shorter time scales within a growing season. Using a 39-year record of flowering phenology, I show that species-specific shifts in the timing of flowering in response to climate change can substantially reshape a subalpine plant community over this time period. Community phylogenetic analyses reveal that these changes are largely independent of evolutionary history. Using a laboratory experiment, I show that the timing of an important harsh abiotic event-low temperatures that cause frost damage to plants-can differentially affect flowering plant species, with implications for plant demography, community structure, and interactions with pollinators. Finally, I show that plant-pollinator interactions exhibit substantial within-season temporal turnover, and that this temporal flexibility of plant-pollinator interactions from one week to the next is consistent and predictable across years. Taken together, this dissertation provides a multifaceted investigation of the temporal ecology of plant communities and plant-pollinator interactions, revealing the important consequences of ecological timing at short-term and longer-term scales.

Understanding the relative importance of density-dependent and density-independent factors in driving population dynamics is one of the oldest challenges in ecology, and may play a critical role in predicting the effects of climate change on populations. We used long-term observational data to describe patterns in plant population regulation for 57 forb and grass species from three different ecosystems (arid desert grassland, semiarid sagebrush steppe, and subhumid mixed-grass prairie). Using a hierarchical partitioning approach, we (i) quantified the relative influence of conspecific density, heterospecific composition, and climate on temporal variation in population growth rates, and (ii) asked how the relative importance of these drivers depends on site aridity, species growth form and life expectancy, and abundance and spatial patterns. The data from one of the sites in this analysis are presented in one of the chapters of this thesis. We found that density-dependence had the strongest effect on species. Climate often had a significant effect, but its strength depended on growth form. Community composition rarely explained significant variation in growth rates. The relative importance of density, composition, and climate did not vary among sites, but was related to species' life histories: compared to forbs, grasses were more sensitive to climate drivers. Abundance and spatial clustering were negatively correlated with the importance of density dependence, suggesting that local rarity is a consequence of self-limitation. Our results show that interspecific interactions play a weaker role than intraspecific interactions and climate variability in regulating plant populations. Forecasting the impacts of climate change on populations may require understanding how changes in climate variables will affect the strength of density-dependence, especially for rare species.

No description available.

No description available.

Research in grassland ecosystems worldwide has highlighted the crucial role many burrowing herbivore mammals provide as so-called “ecosystem engineers”. Many of these examples come from North America and have mostly been focused on Prairie Dogs (Cynomys sp.), which, due to their burrowing and grazing activities, are considered as a species of high ecological importance. Multiple studies have shown that their loss reduces grassland ecosystem functions and that their activities increase plant, arthropod, bird and mammal biodiversity, grassland heterogeneity, provide benefits to cattle, among many other key ecological roles. However, prairie dog species are distributed throughout multiple landscapes in North America, and most of the studies have been on mixed prairie grasslands. It is therefore not surprising that, when comparing the effects of different prairie dog species across ecoregions, the role of prairie dogs is not as clear and results vary, depending on spatial context, type of grasslands, climate and environmental conditions. Yet, grasslands are considered as some of the most highly threatened ecosystems, having high rates of conversion, desertification and biodiversity loss. Therefore, it is imperative to understand the effects prairie dog species have on the ecosystem. In this thesis, I focus on the Mexican prairie dog (C. mexicanus), a species in drastic decline due to habitat loss, caused by agriculture, overgrazing, human settlement, fragmentation, diseases (e.g. plague) and past eradication programs. C. mexicanus is considered endangered by the IUCN red list of threatened species and The Convention of International Trade in Endangered Species of Wild Fauna and Flora. It is also endemic to the Grassland Priority Conservation Area (GPCA) of El Tokio, located in Northeast Mexico within the Chihuahuan desert ecoregion and designated as a GPCA by the Commission for Environmental Cooperation (a cooperation between Canada, U.S. and Mexico) in 2009. Grasslands within GPCA El Tokio are highly fragmented as a result of many years of intense agricultural practices and other anthropogenic activities and around 90% of the original grasslands have been lost. However, it is considered an area of ecological importance due to its unique vegetation and edaphic associations, as well as being a key habitat for migratory birds. Up until now, very few studies have explored the role C. mexicanus has on plant taxonomical diversity and soil properties. Moreover, no studies focusing on prairie dogs have looked into the effect the species has on plant functional diversity or soil properties. Furthermore, GPCA El Tokio is a data-scarce area. Therefore, at this point, basic information and system understanding are urgently needed in order to identify which conservation efforts are most promising and which specific sites these efforts should focus on. Understanding the influence of prairie dog disturbance on vegetation parameters (taxonomic and functional), soil properties and their interaction with environmental conditions through time, will increase knowledge on the risks and vulnerability of grasslands, promoting solutions that can support grassland management. Furthermore, there is a clear gap in the literature about the varying effects of prairie dogs depending on different grassland types and environmental conditions. To study such conditions, I first classified and controlled for factors that could influence prairie dog ecosystem engineering effects addressing the following two general questions: (1) Which grassland types are present in GPCA El Tokio? (2) Do the different grassland types present in GPCA El Tokio influence prairie dog colony sizes and burrow density? When influencing factors were confirmed, I then assess the effects of prairie dog disturbance on vegetation and soil to answer the following questions: (3) Are there clear distinctions across GPCA El Tokio grassland environmental variables? (4) Do the different grassland types present in GPCA El Tokio influence prairie dog colony sizes and burrow density? To do so I selected a representative sample of sites covering the varying environmental conditions present in GPCA El Tokio grasslands, a data-driven clustering approach was used. Once clusters were defined, average burrow density was estimated from remote sensing imagery. To study vegetation measures I first, sampled plant species (92 species and 28 families and 6 traits) to obtain taxonomical and functional diversity measures, and obtained variables related to nutrient availability, carbon and climate regulation, and water regulation and purification. To study the effects on soil a total of 11 soil properties were obtained (382 samples were analyzed). Field work was done during the wet season and repeated during the dry season to obtain season variations of all measures. Soil measures were further obtained at depths of 0-10cm and 10 to 20cm. Results from the study classify GPCA El Tokio into 8 different grassland types with 4 clusters being the most dominant, named Agriculture, Arid, Calcareous, Mountain. I found agricultural grasslands had significantly lower colony sizes compared to calcareous grasslands when outliers were considered, but no differences when outliers were removed and burrow density varied depending on the grassland type, with mountain grasslands having a significantly lower burrow density compared to agricultural and calcareous grasslands. Regarding the effects of prairie dogs on vegetation and soil my findings suggest that functional metrics and community weighted mean (CWM) analyses responded to interactions between prairie dog disturbance, grassland type and season, whilst species diversity and cover measures were less sensitive to the role of prairie dog disturbance. I found weak evidence that prairie dog disturbance has a negative effect on vegetation structure, except for minimal effects on C4 and graminoid cover, but which depended mainly on season. Grassland type and season explained most of the effects on plant functional and taxonomic diversity as well as CWM traits. In the case of soil properties WOP grasslands tended to have higher nutrient availability than WP grasslands. However, mounds played a key role within WP grasslands. Mounds reduce compaction and increase nutrient levels of soil organic carbon, nitrogen, potassium, magnesium, and phosphorus. Such an effect was particularly present in calcareous and arid grasslands, and in many cases the effect was enhanced under wet conditions. In general, the effect of disturbance on soil property changes was dependent on environmental conditions. Overall, my study shows evidence that grassland type and season have a stronger effect than prairie dog disturbance on the vegetation of this short-grass, water-restricted grassland ecosystem.:3 TABLE OF CONTENTS Declaration of conformity 2 1 Acknowledgments 3 2 Extended Summary 5 4 List of Figures 11 5 List of Tables 13 1 Introduction 1 1.1 Importance of grasslands 1 1.2 Grassland conservation and ecosystem engineers 2 1.3 Prairie dogs: ecosystem engineers of grasslands in North America 3 1.4 Distribution of prairie dogs across North American grasslands 6 1.5 Current threats and conservation of the Mexican prairie dog C. mexicanus 7 1.6 Research questions, aims and objectives 9 2 Scientific background 13 2.1 Differences in grassland definitions and classifications 13 2.2 Dryland biases in grassland research 13 2.3 Research gaps on C. mexicanus 15 2.4 Functional diversity and disturbance 16 2.5 Soil complexity and limited research 17 3 Study Area: Grassland Priority Conservation Area of El Tokio 19 3.1 General overview 19 3.2 Bioregions, geology, topography and soils 20 3.3 Climate 23 3.4 Ecoregions, Land cover and Biodiversity 24 3.5 Anthropogenic activities and environmental issues 28 4 Assessing and classifying factors that could influence prairie dog ecosystem engineering effects 31 4.1 Data-driven identification of grassland types 33 4.1.1 Introduction 33 4.1.2 Methods 33 4.1.3 Results 36 4.1.4 Discussion and conclusion 39 4.2 C. mexicanus colony trends and differences across grassland types 41 4.2.1 Introduction 41 4.2.2 Methods 42 4.2.3 Results 48 4.2.4 Discussion and conclusion 52 5 Prairie dog disturbance effects on vegetation and soil across different grassland types and seasons 55 5.1 General methodology 57 5.1.1 Selection of grassland locations 57 5.1.2 Defining study sites and plots 58 5.1.3 Vegetation and soil sampling design 59 5.2 The effect of C. mexicanus on taxonomical and functional diversity across different seasons and grassland types 61 5.2.1 Introduction 61 5.2.2 Methods 63 5.2.3 Results 65 5.2.4 Discussion and conclusion 72 5.3 Soil property responses to the presence of C. mexicanus and its mounds across different grassland types, seasons and depths 77 5.3.1 Introduction 77 5.3.2 Methods 78 5.3.3 Results 81 5.3.4 Discussion and conclusion 88 6 Synthesis 95 6.1 Key findings 95 6.2 Management and Conservation opportunities 97 6.2.1 Designing management plans to suit existing environmental conditions 97 6.2.2 Functional diversity: an opportunity to identify patterns of vegetation across environmental conditions and scales. 98 6.3 Future research 99 6.3.1 Exploration of spatial and temporal effects 99 6.3.2 Mechanistic understanding of disturbance dynamics 100 6.3.3 A need for plant and soil ecological data 101 7 References 103 8 Appendix 131 8.1 Appendix 1. Prairie dog research reference list 132 8.2 Appendix 2. List of individual colonies with areas and other relevant information 140 8.3 Appendix 3. Historical and present colony data. 142 8.4 Appendix 4. Correlation results 144 8.5 Appendix 5. Top 3 models 146 8.6 Appendix 6. Species list per grassland type. 151 8.7 Appendix 7. Correspondence analysis (CA) for each grassland 154 8.8 Appendix 8. Post-hoc results 155 8.9 Appendix 9. Top 3 dominant species. 157 8.10 Appendix 10. HPD credible interval and ROPE. 159