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Questions in community assembly, urban grasslands - Coggle Diagram

- - - - Within patch variability
    - - Community trait composition
        
        Trait diversity
        
        Trait composition can really bring in something new: also relating individual species traits to their responses to connectivity
      - Community phylogenetic composition
        
        Phylogenetic diversity
        
        Phylogenetic composition can bring some nice new things, but it shouldn't probably be the main focus, but something to add to the whole
      - Species numbers / richness / rarity
  - - - e.g. neighbourhood-scale networks as parts of the whole city network
        
        or km2 subnetworks?
        
        one km2 includes a lot of grassland patches...
        
        Maybe could be used for some individual species?
- - - - How do environmental factors affect urban grassland plant communities?
      - Community composition
        
        Species presences and abundances
        
        How do environmental factors affect species presences and abundances in urban grasslands?
        
        Community trait composition
        
        How is community trait space driven by environmental factors?
        
        How does soil affect community trait space?
        
        Probably similar responses as already found, e.g. plant height, SLA, reproduction traits, but if combined to questions of connectivity and habitat suitability, could be interesting
        
        How does urbanisation affect community trait space?
        
        Is it reduced, or maybe partly even widened (e.g. alien species?)
        
        I guess there are a lot of studies on individual trait responses to urbanisation, but somehow studying the whole trait space / trait diversity has been done much less
        
        How does management affect community trait space?
        
        This comparison would probably have to be done between landscape meadows and wastelands, but maybe not so important?
        
        How does habitat age affect community trait space? / successional stage
        
        Older habitats presumable gain more species (if managed) : are they also functionally more diverse : do they gain traits related to e.g. dispersal?
        
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        How does within-patch environmental variability affect community trait space? Does a variable patch have a higher trait diversity?
        
        This could be done from just about any data set?
        
        Trait diversity ~ within patch variaiblity
        
        Are there correlations / clusterings of traits along environmental gradients
        
        What are the main environmental drivers of community trait space variation in urban grasslands?
        
        Soil?/productivity --> SLA, plant height, seed mass, vegetative reproduction, etc., ? --> these also related to management
        
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        Connectivity?
        
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        Habitat type?
        
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        light conditions (e.g. SLA)
        
        There are these methods to combine species matrix, environmental matrix and trait matrix (what was the name) + HMSC, no need to check individual factors separately, but good to keep in mind for e.g. comparing results
        
        This would bring some novelty value definitely
        
        Community phylogenetic composition
        
        How is community phylogenetic composition driven by environmental factors?
        
        How does management regime affect community phylogenetic composition?
        
        How does habitat age / time since last strong disturbance / "successional" stage affect community phylogenetic composition?
        
        How do soil characteristics drive community phylogenetic composition
        
        How does urbanisation affect community phylogenetic composition?
        
        HMSC can also take phylogenetic data...
        
        Community species richness
        
        How is species richness driven by environmental factors?
        
        How is species richness driven by soil characteristics?
        
        How is species richness driven by management?
        
        How is species richness driven by habitat age?
        
        This could be done for road verges, but most landscape meadows are from the 80's (just about), most unmanaged ruderates are young, unless they're really barren
        
        How is species richness driven by urbanisation
        
        General studies over all urban habitats are really numerous, maybe a bit fewer when going to urban grasslands
        
        I guess these all have been studied quite a lot, the responses are probably just the same as in rural grasslands
        
        This alone is not that interesting or new
        
        Can still build e.g. GLM with environmental factors for species richness:
        e.g. richness ~ NH4 + NO3 + PO43 + pH + grainSize + vegetationHeight + NDVI + TWI + landuseType + habitat age + (a huge vector of current and historical landscape indices)
        
        Individual species
        
        How do environmental factors affect individual species presences and abundances in urban grasslands? i.e. what are the species' niches when it comes to their response to environmental gradients?
        
        Species-specific traits
        
        How do species traits affect how they respond to environmental factors, i.e. species niches
        
        Do some plant traits correlate positively/negatively with urbanisation?
        
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        Do some plant traits respond positively / negatively to different management regimes?
        
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        Do some plant traits make the plants respond positively / negatively to different soil factors?
        
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        Do plant traits affect how they react to habitat age?
        
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        Are plants with rare trait combinations also more specialised in habitat requirements?
        
        HMSC
        
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        Species relatedness?
        
        Do closely-related species respond similarly to environmental factors?
        
        Do some phylogenetic groups react positively / negatively to urbanisation?
        
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        Do some phylogenetic groups react positively / negatively to different management levels?
        
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        Do some phylogenetic groups respond positively / negatively to soil factors?
        
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        Do some phylogenetic groups respond positively / negatively to habitat age?
        
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        Differences in patch- and quadrat-level communities
        
        How does within-patch environmental variability affect quadrat-level community variation and sum up to patch-level species composition and species richness?
        
        I can't quickly remember if this has been done much in urban grasslands
        
        Variation in: soil characteristics, productivity, tree cover, vegetation height / rocky cover / bare soil cover : quite a few variables can be derived from Helsinki region's high-resolution land cover data
        
        This could be cool to check anyway, maybe not a focus point, but can be kept in mind, there will definitely be more and less variable sites
        
        Add variability as an explanatory variable. Use land cover variability, soil variability, plant variability (some kind of index for calculating variability from quadrat data, e.g. shared species, species accumulation with quadrats, etc.?)
        
        Inter-community variability
        
        How do environmental factors (and their spatial variability) affect urban grassland variability and beta-diversity?
        
        How do different kinds of communities spatially locate within the city according to environmental variation?
        
        Mapping plant communities and how they locate within the city
        
        How do species / plant traits / phylogenetic groups spatially distribute to the city according to environmental variation?
        
        E.g. species, traits, phylogenetic groups responding to urban centres, neighbourhoods, forested areas: --> km2 data?
        
        Are newly built housing areas holding different plant communities as compared to older areas of the city?
        
        Mapping habitat age for each city patch...
        
        Which kind of landscape configuration maximizes biodiversity?
        
        Areas with higher vs. lower landscape variability?
        
        Calculate landscape diversity indices for the study sites, calculate landscape diversity for km2 quadrat data
        
        --> grassland network in Helsinki region
      - How does environmental variation affect dispersal?
        
        Poorer-quality landscapes should profit generalist species that do well in these too, higher-quality landscapes should profit also more specialised species / moreover, agglomerations of e.g. dry / mesic / rocky grasslands should be beneficial for species specialised to them
        
        Areas with continuums of high-quality grasslands should be richer in species, but also act as dispersal sources for neighbouring novel grasslands /// In contrary, novel grasslands in strongly transformed habitat contexts should be less prone to dispersal, particularly that of more specialised species
        
        Landscape quality (e.g. by using NDVI?) vs. degree of specialisation
        
        Within-patch environmental variation should create more micro-environments that might benefit dispersal overall
        
        Especially patchy vegetation with exposed mineral soil
        
        Amount of suitable habitats for species
        
        Environmental niche hypervolume
        
        Including species abundances?
        
        Large for habitat generalists, smaller for specialists
        
        Most importantly, responses to soil (partly to management: unamanaged / managed), including regeneration micropatch requirements, (maybe also land-use type), niche width related to habitat age: this is related to dispersal too?
        
        Estimated/modelled amount of suitable habitat including degree of suitability
        
        Environmental variability within grassland subnetworks
        
        Abundant productive grasslands can inhibit dispersal of species related to less productive sites (e.g. annuals requiring regeneration microsites)
        
        Dry subnetworks host more specialists + higher species richness than productive subnetworks, since more species tend to prefer drier sites? Over-productive networks the poorest?
        
        Environmental variation, dispersal and patch-scale communities
        
        Patches are richer in species if connected to environmentally similar patches?
        
        Especially, if dry sites are connected with dry sites. If productive sites have more generalist species in them, these may come from several types of habitats?
        
        Model, which species respond to which landscape factors, and if there's a connection between degree of specialisation and response to connectivity
      - How does environmental variation / filtering affect grassland subnetworks?
        
        soil and grassland subnetworks
        
        More productive subnetworks poorer in species + specialists: these tend to be more frequent?
        
        Subnetworks with less productive soil richer in species + specialists?
        
        Management and grassland subnetworks
        
        Management increases subnetwork species richness
        
        Environmental variation in general increases subnetwork species richness, but optimal state with abundant "high-quality" grasslands
    - - How do dispersal processes affect urban grassland plant communities?
        
        Community composition
        
        How do dispersal processes affect individual species?
        
        Which species are vs. are not dispersal-limited?
        
        How are species limited by dispersal vs. habitat suitability?
        
        Habitat suitability easier to estimate
        
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        How to separate pure dispersal capability from habitat suitability?
        
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        Do generalist species also disperse effectively?
        
        Are the species first to arrive in grasslands also typically generalist species?
        
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        Common species can be supposed to disperse effectively, if they occur very probably just about everywhere : rare species only occur locally
        
        Why are species common vs. rare in urban grasslands?
        
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        If comparing e.g. newly built areas (with poor species pools) vs. older cultural landscapes with also semi-natural grasslands and their specialist species
        
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        Which traits are related to good / poor dispersal / responses to connectivity? Do plants in some phylogenetic groups disperse better than others?
        
        There's research on e.g. semi-natural grasslands, but less from urban grasslands. Maybe there's some specific interaction between dispersal and other factors in the urban context?
        
        Which individual traits / combinations of traits are related to response to connectivity
        
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        Uroy et al. 2019: landscape connectivity and plant traits seems to be a very poorly studied topic overall, not only in urban grasslands.
        
        How does dispersal affect plant communities?
        
        Are well-connected communities richer in species / traits / phylogenetic composition?
        
        Do well-connected communities have more grassland specialists?
        
        Species richness / trait diversity / phylogenetic diversity ~ connectivity indices + environment
        
        How does dispersal affect the difference between quadrat- and patch-scale communities?
        
        Are there signs that dispersal is also limited within patch? / e.g. is there spatial autocorrelation of community structures between quadrats, and that can't be explained with environmental variation? --> probably too few quadrats for this anyway?
        
        Quadrat similarities in soil vs. covers?
        
        In some newer sites, it looked like many species had started to disperse starting from the edges, but didn't notice this in older sites. However, e.g. edge effects partly visible: road edge, forest, edge.
        
        How does dispersal affect inter-community variability?
        
        Up to which distance / level of connectivity are nearby communities compositionally similar (sign of effective dispersal, or a formerly connected remaining communities (unless all grasslands newly built))
        
        This response consists of the responses of individual species
        
        Which species are always there, which don't seem to spread at all (even though even some of the most specialised species may probably disperse nearby if there are suitable habitats) and which do show some spatial autocorrelation (these are the species that explain the variation in community similarity)
        
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        Are grasslands in areas with more novel grasslands / more semi-natural grasslands also richer in species?
        
        e.g., If we took two dry road verges, the other one in a poor landscape, and the other one next to a semi-natural grassland, would the latter one tend to have a richer plant community?
        
        Which factors affect plant dispersal and thus plant community composition in urban grasslands?
      - Dispersal and grassland subnetworks
        
        Well-connected subnetworks are more species-rich + host more specialists?
        
        Especially if containing many dry sites and sites with long-term grassland continuity
    - - How do species interactions affect species presences and abundances in urban grasslands?
        
        Continue with this : e.g. signs of zoochory / endo/exozoochory + pollination traits being important for plant dispersal?
        
        One of the main factors related to competition is soil productivity: high productivity is related to tall, competitive, weedy species (with e.g. high SLA) as compared to less productive sites with especially many grassland specialists, often low-growing, low SLA, less competitive
        
        This would be nothing new, unless combined very smoothly and maybe also visually the whole community assembly process, and e.g. the related trait spaces
        
        If we sometimes find both strongly competitive and poorly competitive species both in productive and poor sites, and notice a systematic relationship between their relative abundances, and furthermore, a systematic link between plant traits explaining this relationships, can this be seen as a sign of competition, as modulated by the productivity gradient?
        
        Responses to connectivity: generalists arrive even to poorly connected sites and might gain higher abundances than in better connected sites with more specialist species : this is also competition of a kind
      - HMSC framwork allows for the analysis of residual associations between species, not explained by the other factors included in the model : this needs interpretation and can be tricky to contribute this variation to any particular factor
      - Species interactions and connectivity
        
        Plant-plant competition can be expected to suppress plant establishment and dispersal
        
        Tall-vegetated, competitive, productive sites can be assumed to gain fewer species over time than poorer sites with patchy vegetation. (This happens not only due to differences in establishment, but also survival with competition) -- > difficult to separate from the general productivity gradient?
        
        Even with equal soil conditions, managed grasslands can be expected to gain species quicker than unmanaged sites, since cutting creates space for smaller and less competitive plants, especially if the cut material is removed
        
        This relates to the combined environment / species interaction filter to suppress the establishment of many grassland plants in the more productive, competitive sites. They are often not suitable habitats to start with.
    - - Aronson et al. 2016
        
        Global scale human facilitation filter
        
        Urban morphology and history filter
        
        How does the city history affect urban grasslands?
        
        Building new (e.g. residential) areas, road verges, industrial areas etc.
        
        New, colonisable novel grasslands
        
        New areas which exert a poorer propagule pressure for many plants as compared to older habitats?
        
        Old areas of the city
        
        These have had more time for plant colonisation, longer history
        
        These may also have more of the old cultural plant species
        
        Grassland continuums
        
        These areas can be expected to have the most grassland specialists?
        
        Areas with long grassland history with more or less adequate management
        
        At the same time, these can be expected to be the best propagule sources for at least grassland specialists
        
        Up to which distances?
        
        Socioeconomic and cultural filter
        
        How do socioeconomic and cultural factors affect urban grassland plant communities and their spatial structure?
        
        Spatial locations
        
        Landscape meadows prevalently in half-way (neighbourhoods) between most urbanised city-centres + rural areas
        
        Small rocky outcrops preserved throughout the city
        
        Road verges more intensively managed in city centres (even without vegetation, or paved)
        
        Ruderates in?
        
        Check e.g. Roussel & Alexandre 2021? + others
        
        Garden escapes
        
        Garden waste
        
        Landfills + soil transfer
        
        Citizen participation, seed bombs, guerrilla meadows, managing city grasslands as lawns (also "cleaning" dead wood from forests)
- - - - Simple visual estimation
        
        This has been done
        
        e.g. where the grasslands are clustered and seem to form higher-density entities, where are the grasslands that are known to contain lots of species
      - Structural connectivity measures
        
        Graph theory
        
        Delineate grassland patches
        
        Calculate connectivity indices
        
        e.g. indices with grassland proportions and distances
        
        Which nodes are central
      - How similar results do these methods give out? Would visual estimation work just as fine as more complex measures?
      - Semi-functional connectivity
        
        Model habitat suitabilities and probabilities of presence
        
        Based on
        
        Habitat maps
        
        Ruderates
        
        Lawns
        
        Road verges
        
        Landscape meadows
        
        Semi-natural grasslands
        
        Rocky outcrops
        
        Field verges? Forest edges?
        
        Forests
        
        Low park / garden vegetation
        
        NDVI
        
        TWI
        
        Vegetation height model
        
        even habitat age?
        
        management
        
        light regime : lidar-data?
        
        Land cover: bare soils, low vegetation, woody vegetation, rocky cover
        
        Climatic variation within the city
        
        Climate responses from Finland-scale observations and SDMs???
        
        Compare with expert opinions
        
        Electrical circuit theories, resistance maps, least-cost paths, resistant kernel analysis
        
        Model species dispersal capabilities, including a function of traits, expected abundancies (propagule pressure), habitat suitabilities?
        
        Alternatively, try out different dispersal kernels (based on literature?) and what they would mean for connectivity : do lots of observations for a few species from a lot of sites?
        
        What would happen to connectivity if a certain percentage of lawns were turned into grasslands?
      - Functional connectivity
        
        Data with species movements not available
- - - - Nutrients / chemical composition
        
        Main nutrients
        
        K
        
        P
        
        N
        
        NH4+
        
        NO3-
        
        Soluble / insoluble
        
        pH
        
        Other macronutrients
        
        Micronutrients
        
        Heavy metals
      - Moisture
      - Mineral soil type / grain size
      - Humus content
    - - Macroclimate
        
        Temperature
        
        Rainfall
        
        Oceanic/continental gradient (also within Helsinki region)
      - Microclimate
        
        Temperature
        
        Humidity
        
        (light)
      - Urban heat island
    - - Urbanisation gradient
      - Patch connectivity
    - - Building shadows
      - Topography
      - Tree canopy cover