Phylogenetic ecology and the greening of cities

The Impact of Urbanization on the Distribution of Spontaneous Herbaceous Plants in an Ancient City: A Pilot Case Study in Jingzhou, China

Spontaneous herbaceous plants (SHPs) play an essential role in urban biodiversity. Research on the diversity of SHPs has profound implications for the conservation of urban biodiversity and green space management in the process of urbanization. We investigated the habitat, life form, and growth form of SHPs by combining samples and inspections in Jingzhou, in central southern China. Additionally, we chose three typical regions-Ji'nan, Gucheng, and Shashi-for the examination and comparison of biodiversity. The results showed that diverse habitats provided abundant living space for SHPs of different growth forms and life forms in Jingzhou. Water edges with higher humidity do not significantly support more SHP growth forms and life forms, except for pseudo-rosette, partial-rosette, and perennial plants. In addition, both wasteland and road gaps and slopes support significantly more SHP growth forms, including erect, tussock, and others. Wasteland supported the vast majority of species, both growth forms and life forms. In the diverse habitats, there are 352 plant species belonging to 70 families and 236 genera in Jingzhou (Ji'nan 184 species, Gucheng 157 species, and Shashi 127 species). Plant species diversity differed according to the level of management. The Ji'nan region had a large number of SHP species because of the less disruptive and milder management implemented in this region. SHPs show good performance and can provide wild landscape effects; therefore, they have the potential to be used in many urban landscaping applications. In the process of urbanization expansion, we should implement the concept of protection and coordinated development in new construction areas. Our study has important implications for the support of SHPs in urban areas.

Macro-Morphological Traits of Leaves for Urban Tree Selection for Air Pollution Biomonitoring: A Review

Urban trees provide different ecosystem benefits, such as improving air quality due to the retention of atmospheric particulate matter (PM) on their leaves. The main objective of this paper was to study, through a systematic literature review, the leaf macro-morphological traits (LMTs) most used for the selection of urban trees as air pollution biomonitors. A citation frequency index was used in scientific databases, where the importance associated with each variable was organized by quartiles (Q). The results suggest that the most biomonitored air pollutants by the LMTs of urban trees were PM between 1-100 µm (Q1 = 0.760), followed by O₃ (Q2 = 0.586), PM_2.5 (Q2 = 0.504), and PM₁₀ (Q3 = 0.423). PM was probably the most effective air pollutant for studying and evaluating urban air quality in the context of tree LMTs. PM_2.5 was the fraction most used in these studies. The LMTs most used for PM monitoring were leaf area (Q1) and specific leaf area (Q4). These LMTs were frequently used for their easy measurement and quantification. In urban areas, it was suggested that leaf area was directly related to the amount of PM retained on tree leaves. The PM retained on tree leaves was also used to study other f associated urban air pollutants associated (e.g., heavy metals and hydrocarbons).

A global horizon scan for urban evolutionary ecology

Research on the evolutionary ecology of urban areas reveals how human-induced evolutionary changes affect biodiversity and essential ecosystem services. In a rapidly urbanizing world imposing many selective pressures, a time-sensitive goal is to identify the emergent issues and research priorities that affect the ecology and evolution of species within cities. Here, we report the results of a horizon scan of research questions in urban evolutionary ecology submitted by 100 interdisciplinary scholars. We identified 30 top questions organized into six themes that highlight priorities for future research. These research questions will require methodological advances and interdisciplinary collaborations, with continued revision as the field of urban evolutionary ecology expands with the rapid growth of cities.

Using SPOT Data and FRAGSTAS to Analyze the Relationship between Plant Diversity and Green Space Landscape Patterns in the Tropical Coastal City of Zhanjiang, China

Urban green spaces provide a host of ecosystem services, the quantity and structure of which play an important role in human well-being. Rapid urbanization may modify urban green spaces, having various effects on plant diversity. Tropical coastal cities have urbanized rapidly in recent decades, but few studies have been conducted with a focus on their green spaces. We studied the responses of cultivated and spontaneous plants, both key components of urban flora, to the landscape structure of urban green spaces and possible social drivers. We analyzed existing relationships between plant diversity indices, urban green space landscape metrics (using Systeme Probatoire d’Observation de la Terre (SPOT) data,), and social factors, including the type, population density, construction age, and GPS coordinates of each Urban Functional Unit, or UFU. We found that UFUs with more green space patches had higher cultivated and spontaneous species richness than those with fewer green space patches. Spontaneous species richness decreased when green space patches became fragmented, and it increased when green space patches were more connected (e.g., via land bridges). Conversely, cultivated species richness increased with green space patch fragmentation. The phylogenetic diversity of both cultivated and spontaneous plants were weakly associated with green space structure, which was strongly driven by land use. Old UFUs and those with larger populations had more green space patches overall, although they tended to be small and fragmented. Green space patch density was found to increase as the UFU age increased. From the viewpoint of knowledge transfer, understanding the effects and drivers of landscape patterns of urban green spaces could inform the development of improved policies and management of urban green space areas.

Phylogenetic farming: Can evolutionary history predict crop rotation via the soil microbiome?

Agriculture has long employed phylogenetic rules whereby farmers are encouraged to rotate taxonomically unrelated plants in shared soil. Although this forms a central tenet of sustainable agriculture, strangely, this on-farm "rule of thumb" has never been rigorously tested in a scientific framework. To experimentally evaluate the relationship between phylogenetic distance and crop performance, we used a plant-soil feedback approach whereby 35 crops and weeds varying in their relatedness to tomato (Solanum lycopersicum) were tested in a two-year field experiment. We used community profiling of the bacteria and fungi to determine the extent to which soil microbes contribute to phenotypic differences in crop growth. Overall, tomato yield was ca. 15% lower in soil previously cultivated with tomato; yet, past the species level there was no effect of phylogenetic distance on crop performance. Soil microbial communities, on the other hand, were compositionally more similar between close plant relatives. Random forest regression predicted log10 phylogenetic distance to tomato with moderate accuracy (R 2 = .52), primarily driven by bacteria in the genus Sphingobium. These data indicate that, beyond avoiding conspecifics, evolutionary history contributes little to understanding plant-soil feedbacks in agricultural fields; however, microbial legacies can be predicted by species identity and relatedness.

A roadmap for urban evolutionary ecology

Urban ecosystems are rapidly expanding throughout the world, but how urban growth affects the evolutionary ecology of species living in urban areas remains largely unknown. Urban ecology has advanced our understanding of how the development of cities and towns change environmental conditions and alter ecological processes and patterns. However, despite decades of research in urban ecology, the extent to which urbanization influences evolutionary and eco-evolutionary change has received little attention. The nascent field of urban evolutionary ecology seeks to understand how urbanization affects the evolution of populations, and how those evolutionary changes in turn influence the ecological dynamics of populations, communities, and ecosystems. Following a brief history of this emerging field, this Perspective article provides a research agenda and roadmap for future research aimed at advancing our understanding of the interplay between ecology and evolution of urban-dwelling organisms. We identify six key questions that, if addressed, would significantly increase our understanding of how urbanization influences evolutionary processes. These questions consider how urbanization affects nonadaptive evolution, natural selection, and convergent evolution, in addition to the role of urban environmental heterogeneity on species evolution, and the roles of phenotypic plasticity versus adaptation on species' abundance in cities. Our final question examines the impact of urbanization on evolutionary diversification. For each of these six questions, we suggest avenues for future research that will help advance the field of urban evolutionary ecology. Lastly, we highlight the importance of integrating urban evolutionary ecology into urban planning, conservation practice, pest management, and public engagement.

Manipulating plant phylogenetic diversity for green roof ecosystem service delivery

Plant species and functional trait diversity have each been shown to improve green roof services. Species and trait differences that contribute to ecosystem services are the product of past evolutionary change and phylogenetic diversity (PD), which quantifies the relatedness among species within a community. In this study, we present an experimental framework to assess the contribution of plant community PD for green roof ecosystem service delivery, and data from one season that support our hypotheses that PD would be positively correlated with two services: building cooling and rainwater management. Using 28 plant species in 12 families, we created six community combinations with different levels of PD. Each of these communities was replicated at eight green roofs along an elevation gradient, as well as a ground level control. We found that the minimum and mean roof temperature decreased with increasing PD in the plant community. Increasing PD also led to an increase in the volume of rainwater captured, but not the proportion of water lost via evapotranspiration 48 hr following the rain event. Our findings suggest that considering these evolutionary relationships could improve functioning of green infrastructure and we recommend that understanding how to make PD (and other measures of diversity) serviceable for plant selection by practitioners will improve the effectiveness of design and ecosystem service delivery. Lastly, since no two green roof sites are the same and can vary tremendously in microclimate conditions, our study illustrates the importance of including multiple independent sites in studies of green roof performance.

Relationships between plant drought response, traits, and climate of origin for green roof plant selection

The ideal species for green or vegetated roofs should have high water use after rainfall to maximize stormwater retention but also survive periods with low water availability in dry substrates. Shrubs have great potential for green roofs because they have higher rates of water use, and many species are also drought tolerant. However, not all shrub species will be suitable and there may be a trade-off between water use and drought tolerance. We conducted a glasshouse experiment to determine the possible trade-offs between shrub water use for stormwater management and their response to drought conditions. We selected 20 shrubs from a wide range of climates of origin, represented by heat moisture index (HMI) and mean annual precipitation (MAP). Under well-watered (WW) and water-deficit (WD) conditions, we assessed morphological responses to water availability; evapotranspiration rate (ET) and midday water potential (Ψ_MD ) were used to evaluate species water use and drought response. In response to WD, all 20 shrubs adjusted their morphology and physiology. However, there were no species that simultaneously achieved high rates of water use (high ET) under WW and high drought tolerance (low Ψ_MD ) under WD conditions. Although some species which had high water use under WW conditions could avoid drought stress (high Ψ_MD ). Water use was strongly related to plant biomass, total leaf area, and leaf traits (specific leaf area [SLA] and leaf area ratio [LAR]). Conversely, drought response (Ψ_MD ) was not related to morphological traits. Species' climate of origin was not related to drought response or water use. Drought-avoiding shrubs (high Ψ_MD ) could optimize rainfall reduction on green roofs. Water use was related to biomass, leaf area, and leaf traits; thus, these traits could be used to assist the selection of shrubs for stormwater mitigation on green roofs. The natural distribution of species was not related to their water use or drought response, which suggests that shrubs from less arid climates may be suitable for use on green roofs. Selecting species based on traits and not climate of origin could both improve green roof performance and biodiversity outcomes by expanding the current plant palette.

Phylogenetic diversity and plant trait composition predict multiple ecosystem functions in green roofs

Plant selection and diversity can influence the provision of key ecosystem services in extensive green roofs. While species richness does predict ecosystem services, functional and phylogenetic community structure may provide a stronger mechanistic link to such services than species richness alone. In this study, we assessed the relationship between community-weighted trait values from four key leaf and canopy functional traits (plant height, leaf area, specific leaf area, dry leaf matter content), functional diversity, and phylogenetic diversity to ten different green roof functions, including ecosystem multifunctionality, in experimental polycultures. Functional traits of dominant plant species were a major driver for indicators of multiple green roof functions, such as substrate nitrate-N, substrate phosphorus, aboveground biomass and ecosystem multifunctionality. In contrast, functional diversity alone increased substrate organic matter. Moreover, both functional/phylogenetic diversity and identity predicted canopy density, substrate cooling. This study highlights the first line of evidence that distinct aspects of phylogenetic and functional diversity play a major role in predicting multiple green roof services. Therefore, we provide further evidence that to maximize green roof functioning, a very careful selection of plant traits and polycultures are needed.