Sealed surfaces limit bird diversity, whereas tall structures may support abundance of some species, while both filter traits in urban landscapes

The urbanization process leads to changes in bird communities’ taxonomic and functional compositions. Highly urbanized areas generally exhibit a reduced number of bird species sharing few functional traits. However, most urban bird studies focused on vegetation patches in temperate cities. In this study, we investigate how urban environmental attributes – noise, height of buildings, and urban vegetation characteristics – modulate species occurrences and the distribution of functional traits across the streetscape of a tropical metropolis. We predicted diverse trait-environment relationships, but that highly urbanized contexts (e.g., noisy streets with tall buildings) would be mostly occupied b,y a lower number of species sharing generalist traits. We also predicted to observe streets with similar community composition (profiles) shaped by environmental conditions and interspecific interactions. We applied hierarchical modelling of species communities as a flexible framework for analysis of community data. We observed that, increased noise exposure and reduced green cover were negatively related with species richness due to their negative relationships with most species’ occurrences. On the other hand, larger number of trees and higher proportion of green cover presented mostly positive relationships with occurrences, and thus with species richness. Throughout our streetscape, community composition was highly heterogeneous and similar conditions led to similar profiles. For example, noisy streets may favor the presence of omnivorous and large-bodied species, while wooded streets may allow for the presence of smaller-bodied forest specialist species that exploit lower vegetation strata. Our results indicate that streetscapes may have the potential to harbor functionally and taxonomically diverse bird communities.

We conducted large‐eddy simulations over 98 urban arrays with varying building densities and height distributions. Compared with uniform‐height urban arrays, the influence of height variability on urban flow is pronounced and acts differently in two idealized urban configurations: the low buildings induce higher wind speed and stronger turbulence over staggered arrays but act inversely over aligned building configurations. The flow motions around tall buildings generate strong dispersive fluxes, which are sometimes of similar magnitude to the turbulent momentum flux and responsible for a persistent isolated roughness flow pattern in the upper canopy regardless of the urban density. Tall buildings further contribute disproportionately to the form drag of the urban surface, reaching up to 3.9 times the form drag induced by buildings of height equal to the average building height, in dense layouts. The flow inflection points—that is, the largest wind‐speed gradient that defines the aerodynamic interface between the urban canopy flow and the surface layer flow above—are found to be displaced to the maximum building height if less than 25% of buildings are below the mean building height. These findings provide critical insight for the development of urban canopy models, where the impacts of height variability on flow are often linked to the vertical variation in urban density alone. To address this deficiency, we provide a case study that considers the drag amplification due to the impact of vertical urban structures in the urban canopy model, enabling high‐resolution regional climate models to reproduce urban air flows better.

Context Urbanization impacts biodiversity through changes in horizontal and vertical structures. While impervious cover is well-studied, the role of building height remains underexplored at a broad scale. Objectives This study aimed (1) to assess whether building height differed statistically from impervious cover and NDVI in explaining bird diversity in cities, and (2) to assess the impacts of building height in conjunction with seven predictor variables: impervious cover, bare, trees, grass, water, shrub and scrub and NDVI. Methods We combined land cover data with an open-access building footprints data. We analyzed over 1 million eBird checklists from 298 cities in the United States. For objective one seven models were evaluated for each city (1) building height, (2) impervious cover, (3) NDVI, (4) building height and impervious cover, (5) building height and NDVI, (6) impervious Cover and NDVI, and (7) building height, impervious Cover and NDVI. For objective two we use model 7 and the rest of the predictor variables to assess the impact of building height. For both objectives, we compared model results by ecoregion. Results Building height, impervious cover, and NDVI were the best single predictors of bird species richness in 10.7%, 10.4%, and 12.4% of cities, respectively. However, the combined model including all three variables performed best in 25.8% of cities, underscoring the complementary influence of vertical and horizontal urban structures in cities. Species richness was positively related to shrub/scrub and water cover, highlighting the importance of these habitats for urban biodiversity. Conclusions Our research advances landscape ecology by incorporating vertical urban structure into biodiversity models, providing new insights into the multidimensional impacts of urbanization on bird communities. Findings underscore the need for context-specific strategies integrating green infrastructure to promote avian diversity in cities.

The interaction between plant diversity and soil physicochemical factors has been predicted to influence the variation in soil microbial diversity across space and time; however, only limited robust evidence has been found to support this prediction at broad scale. We examined the relationships between plant community functional attributes (i.e., community-weighted mean (CWM) and functional trait diversity (FD)) and soil microbial diversity in Tibetan alpine meadows under different environmental regimes. Soil bacterial diversity was weakly associated with plant species diversity but was significantly associated with both CWM and FD of five key functional traits, explaining nearly half of the variation in soil bacterial diversity. Soil bacterial diversity was positively associated with CWM and FD of plant height, leaf specific area, and leaf phosphorus but was negatively associated with CWM of leaf dry matter content. These results provide robust evidence supporting the theoretical prediction that the plant community functional attributes can explain variation in soil bacterial diversity. In addition, these results provide novel insights that could facilitate the understanding of the mechanisms of assembly of soil microbial diversity.

Corrigendum.

Urban morphology refers to the physical form of a city that is constantly transformed and updated in the process of urbanization. A valuable source of data on ‘built forms’ is modern remote sensing technology, which provides a variety of products on building footprints and heights at national, continental, and global levels. A large-scale comparison of urban morphologies is important for assessing urban development as well as its influence on urban ecology; however, this has not been well documented so far. This study includes 41 cities in China and 36 in Europe with various city sizes, population densities, and climate features. We applied 3D landscape metrics and principal component analysis (PCA) to compare the spatial aspects of the urban morphology of these cities. We found: (1) measurements of the building height, surface fluctuation, and texture directionality of urban building layouts in China are higher than those of European cities, while the latter are high-density and compact built landscapes; (2) a significant clustering phenomenon for Chinese and European cities revealed by PCA, with the former showing a much more aggregated pattern, indicating a relatively uniform morphology of urban buildings in China; (3) distinctions between cities in China and Europe are suggested by the first principal component, to which building height, surface fluctuation, building complexity, and spatial distance among buildings contribute significantly; and (4) the second principal component (mainly represented by maximum building height, surface area, volume, and shape metrics) can separate large metropolitan cities and provincial capitals from cities with lower urban population, smaller size, and slower economic development. Our results demonstrate the potential of 3D landscape metrics for measuring urban morphology. Together with a temporal analysis, these metrics are useful for quantifying how urban morphology varies in space and time on a large scale, as well as evaluating the process of urbanization.

Relative influence of environmental, stand factors and functional traits on allocation of forest productivity during the restoration of subtropical forests in central China

Investigating functional plant traits is essential for understanding plant responses and adaptations to global climate change and ecosystem functions. Synchronous observations of multiple plant traits across multiple sites are rare. Here, we obtained community, functional trait, and environmental data for different forest vegetation types in China’s tropical, subtropical, warm-temperate, and cold-temperate zones. Using principal component (PC) analysis, we constructed a composite–habitat gradient axis of biotic and abiotic factors across different climatic zones, differentiated functional trait compositions along the axis and their driving factors, and reached three main conclusions. (1) At the community level, the community-weighted mean and variance of each trait level differed across the climatic zones. Specific leaf areas and leaf phosphorus contents decreased with increasing PC1 values, whereas community-weighted means and variances of leaf dry-matter contents, leaf nitrogen-to-phosphorus ratios, and wood densities significantly increased with increasing PC1 values. However, the leaf nitrogen content varied along the PC1 axis. Both the community-weighted skewness and kurtosis of functional traits increased significantly with increasing PC1 values for the composite habitat gradient across the climatic zones. (2) The weighted mean, variance, skewness, and kurtosis of each functional trait exhibited different patterns on the composite habitat gradient PC2 axis than on the PC1 axis across the climatic zones, and the correlation was weak. (3) Most functional traits correlated significantly with the community-weighted mean and variance, kurtosis, and skewness. Therefore, the different functional trait compositions of forest communities in different climatic zones reflected trait convergence caused by the environment and trait differences caused by species competition in response to local-scale filtering.

ABSTRACTNarrow, unpaved forest roads and paths are a ubiquitous feature of managed forest landscapes worldwide, with the potential to influence bird communities. However, compared to large roads, the effects of structural changes to the understory and canopy generated by unpaved forest roads and paths are less understood. In this study, we investigate the influence of narrow linear openings in the forest caused by forest roads and paths on bird communities in the southern Black Forest, Germany. We surveyed bird communities in four distinct plot types, including two “linear openings”: forest interior, forest paths, forest roads, and forest edges. Forest roads and paths were expected to represent intermediate conditions in terms of openness between interior forests and a forest edge. We aim to understand how these linear openings affect birds' species richness, community composition, and functional traits. Our results show that while species richness remains similar among plot types, the community composition at forest edges differs. The indicator analysis reveals indicator species for each type of plot. In addition, functional traits like body mass and wing shape showed a weak response to the linear openings. The findings suggest that although unpaved forest roads and paths potentially introduce resources and structural modifications in the forest structure, the effect on the birds seems limited compared to pronounced habitat transitions, such as forest edges. These narrow linear infrastructures are often necessary for forest use by humans and can be unnoticeable for birds when carefully planned on a small scale. Nevertheless, forest managers should not overlook broader‐scale effects (e.g., potential habitat loss, predation). Our findings contribute to a better understanding of birds' responses to linear and small‐scale fragmentation introduced by unpaved forest roads and paths. However, more research is needed to distinguish the ecological impacts and management implications for bird communities in temperate managed forests along a gradient of linear openness.

Emergency medical services (EMS) care may be delayed when out-of-hospital cardiac arrest (OHCA) occurs in tall or large buildings. We hypothesized that larger building height and volume were related to a longer curb-to-defibrillator activation interval. We retrospectively evaluated 3,065 EMS responses to OHCA in a large city between 2003–13 that occurred indoors, prior to EMS arrival, and without prior deployment of a defibrillator. The two-tiered EMS system uses automated external defibrillator-equipped basic life support firefighters followed by paramedics dispatched from a single call center. We calculated three time intervals obtained from the computerized dispatch report and time-synchronized defibrillators: initial 911 call to address curb arrival by first unit (call-to-curb), curb arrival to defibrillator power on (curb-to-defib on), and the combined call-to-defib on interval. Building height and surface area were measured with a validated program based on aerial photography. Buildings were categorized by height as short (<25 ft), medium (26–64 ft) and tall (>64 ft). Volume was categorized as small (<60,000 ft3), midsize (60,000–1,202,600 ft3) and large (>1,202,600 ft3). Intervals were compared using the two-tailed Mann-Whitney test. EMS responded to 1,673 OHCA events in short, 1,134 in medium, and 258 in tall buildings. There was a 1.14 minute increase in median curb-to-defib on interval from 1.97 in short to 3.11 minutes in tall buildings (p < 0.01). Taller buildings, however, had a shorter call-to-curb interval (4.73 for short vs 3.96 minutes for tall, p < 0.01), such that the difference in call-to-defib on interval was only 0.27 minutes: 6.87 for short and 7.14 for tall buildings. A similar relationship was observed for small-volume compared to large-volume building: longer curb-to-AED (1.90 vs. 3.01 minutes, p < 0.01), but shorter call-to-curb (4.87 vs. 4.05, p < 0.01); the difference in call-to-defib on was 0.18 minutes. Both taller and larger-volume buildings had longer curb-to-AED intervals but shorter 911 call-to-curb arrival intervals. As a consequence, building height and volume had a modest overall relationship with interval from call to defibrillator application. These results do not support the hypothesis that either taller or larger-volume buildings need cause poorer outcomes in urban environments.

Extreme precipitation events are becoming more intense and frequent due to climate change. This climatic shift is impacting the structure and dynamics of natural communities and the key ecosystem services they provide. Changes in species abundance under these conditions are thought to be mediated by functional traits, morpho‐physiological characteristics of an organism that impact its fitness. Future environmental conditions may, therefore, favour different traits to those in present‐day communities. After 6 years of manipulated precipitation levels, including drought (−50% of ambient precipitation), irrigation (+50% of ambient precipitation), and control (ambient precipitation), we measured five key functional traits (plant height, leaf dry matter content [LDMC], leaf thickness, specific leaf area [SLA], and leaf phosphorus concentration) in 586 individual vascular plants to study the effects of precipitation changes on community‐weighted functional traits. Additionally, we tested whether the precipitation change effects on the traits depend on the time of the growing season. As expected, reduced precipitation impacted community composition only for the late‐season timing, after the seasonal field mowing, but led to a significant change in all community‐level plant traits between season timings. Under drought, communities shifted towards shorter individuals with thicker but small leaves and lower phosphorous content. Overall, a combination of community reassembly and intraspecific variation contributed to community‐weighted differences between control and drought plots for plant height, SLA, and LDMC traits. Species turnover was the main driver of community‐weighted means (CWMs) shifts in all traits in the late‐season but SLA. Whereas all traits showed variations at the community level with drought, SLA and LDMC were the most responsive traits at the species level. Nevertheless, our results suggest underestimation of intraspecific variation due to sensitive species lower abundance under stress. No differences in CWMs of functional traits were observed between control and irrigated plots. Synthesis: Our findings suggest that functional trait composition of grassland communities may shift under climate change‐induced drought, depending on the growing season timings. Trait‐based attempts to predict ecosystem functioning must account for such temporal variation in community trait values.

Questions Despite advances made in disentangling interspecific and intraspecific trait variability, little is known about their coordination. We explored intraspecific trait variability (ITV) of closely related species (to reduce phylogenetic effects) of the Carex genus growing over a broad environmental gradient. We asked whether (i) trait values of Carex species correlate with the community‐weighted mean (CWM) of the same trait, (ii) to what extent Carex species turnover between localities and their ITV is responsible for this relationship, and (iii) the ITV of Carex species increases or decreases similarly to CWM, promoting either pattern of trait divergence or convergence. Location South Bohemia, Czech Republic. Methods We measured three key functional traits (height, specific leaf area—SLA, and leaf dry matter content—LDMC) on populations of 15 Carex species at 72 various localities. We also recorded species composition at each locality to compare Carex species traits with the respective CWMs of the rest of the community. Results SLA was the only trait showing significant correlation between Carex species and CWM. This relationship was largely driven by a turnover of Carex species along the gradient of CWM, but ITV strengthened this relationship and increased similarity to CWM. Plant height of Carex species did not correlate with CWM, and LDMC did not show a consistent pattern among Carex species. Conclusion ITV of SLA appears to be driven by trait convergence, which indicates environmental filtering for this trait. SLA is a highly variable trait, which was filtered toward optimal SLA values. This allows a more efficient capture of the energy from light and enables species to occupy a broader range of environmental conditions. The extension of conditions which species tolerate due to ITV is, however, limited compared to species turnover, which allows for a substantially broader spectrum of interspecific trait variability.

The relationships between community-weighted mean (CWM) functional traits and ecosystem functions have been extensively studied. However, how CWM traits and ecosystem functions respond to grazing types and whether the relationships between CWM traits and ecosystem functions mediate the response of ecosystem functions to grazing types remains controversial. In the present study, we set up a seven-year grazing experiment with four grazing types: no grazing (NG), cattle grazing (CG), sheep grazing (SG), and mixed grazing by sheep and cattle (MG) on Inner Mongolia grassland. Nine functional traits of dominant species and five ecosystem functions under different grazing types were determined, and the relationships between CWM traits and ecosystem functions were analyzed. The results showed that the CWM height decreased after grazing, while the CWM nitrogen and phosphorus contents increased after CG. SG caused a greater decrease in aboveground biomass (AGB) and a greater increase in the net ecosystem CO2 exchange (NEE) of grassland ecosystems than did CG. This result may be partially because the CWM nutrient content and NEE were more negatively related after CG; and the increase in the CWM nitrogen and phosphorus contents suppressed NEE after CG. Therefore, to protect the sustainability of grassland ecosystem functions, SG should be reduced. Additionally, our work emphasizes that the relationships between plant functional traits and ecosystem functions may mediate the response of ecosystem functions to grazing types.

The paper focuses on tall timber buildings. The major aim of this paper is to identify the most sustainable and efficient structural system to increase the height of timber buildings, also considering steel–timber hybrid structures. First of all, a brief review of tall buildings’ evolution is presented to understand why tall timber buildings are considered nowadays and which are the most adopted structural solutions. Then, the case study of the tallest timber building in the world is selected and utilized as an archetype. Once the model has been validated, seven alternative structural systems are considered by varying the horizontal load resisting system and preserving the same member cross-sections as the reference building. The variants are tested and compared in terms of material consumption, vibration characteristics and lateral load response. Using the best structural system, the height of the building is increased, pushing the structures beyond the current limits and identifying the most efficient option. The idea is to preserve the column cross-sections and balance the increase in gravity loads due to the additional floors by replacing the concrete floors with timber counterparts. With the same structural system, equivalent steel–timber hybrid solutions are finally tested and compared in terms of sustainability to timber-only counterparts and to the original project. The results of analyses show that the use of steel elements combined with timber can lead to optimized and sustainable structural solutions.

The effects of streets on biodiversity is an important aspect of urban ecology, but it has been neglected worldwide. Several vegetation attributes (e.g. street tree density and diversity) have important effects on biodiversity and ecological processes. In this study, we evaluated the influences of urban vegetation—represented by characteristics of street trees (canopy size, proportion of native tree species and tree species richness)—and characteristics of the landscape (distance to parks and vegetation quantity), and human impacts (human population size and exposure to noise) on taxonomic data and functional diversity indices of the bird community inhabiting streets. The study area was the southern region of Belo Horizonte (Minas Gerais, Brazil), a largely urbanized city in the understudied Neotropical region. Bird data were collected on 60 point count locations distributed across the streets of the landscape. We used a series of competing GLM models (using Akaike's information criterion for small sample sizes) to assess the relative contribution of the different sets of variables to explain the observed patterns. Seventy-three bird species were observed exploiting the streets: native species were the most abundant and frequent throughout this landscape. The bird community's functional richness and Rao's Quadratic Entropy presented values lower than 0.5. Therefore, this landscape was favoring few functional traits. Exposure to noise was the most limiting factor for this bird community. However, the average size of arboreal patches and, especially the characteristics of street trees, were able to reduce the negative effects of noise on the bird community. These results show the importance of adequately planning the urban afforestation process: increasing tree species richness, preserving large trees and planting more native trees species in the streets are management practices that will increase bird species richness, abundance and community functional aspects and consequently improve human wellbeing and quality of life.