Urban Ecosystems最新文献

Although much attention has been paid to improve the representation of the urban spatial complexity, most efforts have been limited to the inclusion of green cover data to describe the biological component of cities, leaving the measurement of crucial urban ecological properties out of the picture. To tackle this, the Urban Ecosystem Integrity Index (UEII) was recently proposed to spatially represent the interplay between the intensity of urbanization and the biological components of cities, including urban biodiversity. The UEII has shown to be effective in measuring the ecosystem integrity of a Neotropical city; however its generalized applicability remains to be tested. Thus, here we tested the suitability of the UEII when applied in a boreal city and also evaluated if it adds more valuable information than the NDVI (also contrasting it with a UEII previously published for a tropical city), which is often suggested as a proxy of urban greenness and therefore the ecology of cities. We calculated the UEII by considering land surface temperature, built-up cover, and native plants and bird species richness of the city of Lahti, Finland (Palearctic; boreal). The UEII showed to be robust, comparable, and effective in capturing the intra and inter-urban spatial heterogeneity of both cities. Moreover, although the UEII and NDVI values correlated, the variance in such correlation showed the detail that the UEII brings to the quantificaiton of the ecological integrity of the cities, representing a more integral indicator. Thus, our findings indicate that the UEII is a valuable tool to inform on areas requiring ecological enhancement, as well as identifying those that are thriving, in cities ranging from tropical and highly biodiverse to boreal and with considerable less biodiversity.

The loss of forest cover in urban landscapes alters the dynamics of spatial and food resources, challenging the maintenance of forest species, which may have their condition compromised. Dung beetles are sensitive to changes in vegetation structure and land use caused by human activities, processes that are intrinsically related to the establishment and development of cities. The aim of this study was to evaluate the effect of landscape structure on the abundance and morphological characteristics of two species of dung beetle (Dichotomius boreus and Dichotomius quadrilobatus) that inhabit forested areas in urbanized landscapes in the Amazon region. We carried out the study in 38 landscapes located in six urban regions in the central region of the Amazon. We evaluated the effect of landscape structure, at the site and city scales, on beetle abundance, individual body size, and relative horn length of males. At the local scale, landscapes with greater forest cover showed greater abundance of dung beetles, as well as greater lengths of D. boreus horns. Cities with a greater amount of forest cover had larger individuals than those with less forest cover. We conclude that forested areas in urban landscapes are a key habitat for the maintenance of dung beetle populations with a strong relationship between the amount of forest cover in the landscape. The maintenance of healthy and abundant populations of beetles in urban Amazonian landscapes guarantees the persistence of ecosystem services provided by these organisms in urban ecosystems.

Abstract

Urbanization progresses world-wide and the frequency of biological invasions increases. Understanding to what extent urban environments facilitate biological invasions and how this affects ecosystems within and outside urbanized areas thus becomes crucial. We here examine the role of urban environments in the invasion of the butterfly Pieris mannii that expanded across Central Europe within the last two decades. Using standardized butterfly captures at paired urban and (semi)natural field sites within the invaded range in Switzerland, we demonstrate that P. mannii is strongly associated with cities and towns. At least in some urban localities, this species is now the most common butterfly, and densities tend to be particularly high where urban areas are large. Because urban habitats commonly provide non-native host plants and perhaps also the physical structure and microclimate suitable to this butterfly, urbanization has clearly promoted the species’ rapid invasion. Studying phenology over an entire season, we further infer that P. mannii has up to six generations per year, which may allow the species to adjust its life cycle to changing season length during northward expansion. Overall, our study demonstrates how preadaptation to urbanized environments in a relatively specialized insect increases urban biodiversity on a large geographic scale.

The vocal behavior of Neotropical birds has received less attention compared to birds in Northern temperate regions. Many bird species rely on acoustic communication to establish and maintain territories and to interact with conspecifics. For this reason, the growing threat of noise pollution in their habitats is a cause for concern. Birds perform behavioral adjustments when confronted with atypical environmental situations (e.g. urban noises, artificial light, human voice or vegetation loss). The aim of this study was to investigate vocal adjustments of Masked Gnatcatcher (Polioptila dumicola) males in environments located near a route with varying level of traffic noise (measured in decibels) and differing percentage of cover vegetation. Linear mixed models (LMMs) were used to analyze the effects of both environmental parameters in P. dumicola song. Results reveal that P. dumicola increases the amplitude of its songs in response to higher levels of traffic noise. Cover vegetation did not show any effect on song parameters. The model with the highest significance demonstrates a positive linear relationship between amplitude and traffic noise. These findings underscore the importance of studying communication alterations in noisy environments and understanding the ecological consequences of such effects on bird populations.

Of 6,012 surveyed trees, 353 hosted mistletoes, but 50 of 96 species did not.

Four tree-related factors affected mistletoe prevalence (3 positively/1 negatively).

Only tree size (positively) affected infection intensity.

Abstract

The floristic richness of Bosnia and Herzegovina has been extensively studied, however urban flora has only recently garnered attention, but no systematic surveys of urban ecosystems have been carried out. To address this problem, a study of the seven urban floras in Bosnia and Herzegovina was conducted to determine the pattern of floristic diversity and correlation with anthropogenic factors: size of the urban area, ratio of green areas in the total urban area, number of inhabitants, and population density. The first finding of the study is that urban floras in Bosnia and Herzegovina are rich in plant species. The results have shown that the urban floristic diversity largely reflects the natural vegetation of the urban environment, compared to urban floras in other parts of Europe. Species structure reflects the geographical location as well, so are the urban areas in the Mediterranean biogeographical region, Mostar and Blagaj, floristically richer, but at the same time species richness correlates with the total urban area, as in Sarajevo and Banja Luka. Moreover, the proportion of alien species is low and there is no pronounced process of floras homogenisation. Of the anthropogenisation factors, population density correlates most strongly with the richness of urban flora. From the results, we have concluded that urban plant diversity correlates with both environmental and anthropogenic factors, in a way that provides a basis for establishment of conservation programs in urban ecosystems.

Urban green cover provides ecosystem services for human well-being and better conditions for biological conservation. Structural analysis and monitoring across space and time at landscape scale can aid better design and management of urban green cover. In this study, we used Sentinel-2 satellite imagery and semiautomatic reclassification methods (i.e., supervised classification) in Google Earth Engine (GEE), to analyze changes in built and urban green cover of Medellín and adjacent municipalities (Colombia) between 2016 and 17 and 2022-23. We used total area, patch number, mean patch area, and patch cohesion index as proxies of landscape structural changes, differentiating grass from trees. Built cover increased its total area from 77.1 to 80.5%, whereas grass and trees decreased it from 6.4 to 5.8%, and 16.6–13.8%, respectively. Built cover decreased in patch number by 1.4% and increased in mean patch area from 7.08 to 7.72 ha, whereas trees decreased in patch number by 7.8% and grass increased by 9.2%. Both green cover categories decreased in mean patch area (trees: 0.27 to 0.23 ha; grass: 0.24 to 0.15 ha). Otherwise, the patch cohesion index decreased in grass and trees, while in built cover it remained constant over time. Urban green cover in Medellín urban area and adjacent municipalities is increasingly reduced and isolated, whereas urbanization sprawls and densifies, suggesting that local development policies need improvement to prevent urban green cover degradation.

Urban expansion is an important cause of biodiversity loss due to habitat destruction involving the replacement of the natural environment with anthropic infrastructure. However, recent studies suggest that the harmonious growth of cities could allow the persistence of biological diversity within them. Thus, some cities, especially those that contain remnant forests that preceded their expansion, could harbor high levels of biodiversity. These remnant forests, i.e., urban natural forests (UNFs), are refuges for native species, providing suitable habitat conditions for population stability. However, traditional ecological studies have focused on natural and planted forests, so our knowledge of ecological dynamics in UNFs is still limited. Here, we explore the suitability of a temperate UNF for saproxylic beetles. These beetles are deadwood-dependent, highly diverse trophic groups that commonly inhabit natural forest ecosystems. However, saproxylic beetle diversity has been understudied in urban forest ecosystems. We analyzed the species richness, abundance, and seasonal variation of saproxylic beetles, including their most important trophic guilds, associated with urban forests. For this purpose, we monitored standing dead trees monthly between December 2019 and December 2022, using trunk window (flight interception) traps in the UNF Arboretum of Valdivia, Chile. Additionally, we measured qualitative and quantitative habitat attributes to evaluate the preferences of these insects in the UNF. We used generalized linear models as statistical methods to estimate saproxylic beetle habitat preferences. We collected 1273 individuals, belonging to 43 families and 195 saproxylic species/morphospecies. We found that diversity and abundance were strongly influenced by seasonality and the degree of decomposition of deadwood, with increased diversity and abundance in warmer months and highly decomposed trees. Our data show that UNF Arboretum harbor a high diversity of saproxylic species and are therefore suitable habitats and that the factors that regulate these assemblages are homologous to those of natural forests. Finally, our research provides evidence useful for the establishment of conservation and management practices to promote high diversity in UNFs, for example increasing the deadwood volume and quality of the habitat for saproxylic diversity.

Ponds are key elements for ecosystem functions in urban areas. However, little is known about pond biodiversity changes over time and the drivers underlying such changes. Here, we tested whether past species assemblages, land cover and pond environmental change influence pond macroinvertebrate species richness and temporal beta diversity. We also compared spatial and temporal beta diversity, and investigated species-specific colonization and extinction rates over time. We sampled for presence of Odonata and Trichoptera (larvae), and Coleoptera and Hemiptera (larvae and adults) species in 30 ponds in Stockholm, Sweden, in 2014 and 2019. Past species richness was the best predictor of current species richness, whereas temporal changes in land cover and pond environment were not significantly related to current species richness. No correlations between temporal beta diversity and land cover or pond environmental changes were detected. However, ponds showed large changes in their temporal beta diversity, with equal contributions from species gains and losses. The probability of species colonizing and going extinct from ponds revealed that more common species were more likely to colonize a pond, while uncommon species were more likely to go extinct in a pond. Within our 5-year study, we found (i) highly similar spatial and temporal beta diversity, (ii) that past species richness is a good predictor of current species richness; however, the same does not hold true for species composition. The high dynamics of urban pond communities suggest that a large number of ponds are required to maintain high species richness at a landscape level.

Abstract

The rapid expansion of urban areas and intense human activities have exerted serious impacts on the structure and service functions of ecosystems. A clear understanding of the interaction between urbanization (UI) and ecosystem service (ES) is of great significance for formulating regulations of future urban development and environment protection. In this study, we analyzed the impacts of urbanization on ecosystem services from 2000 to 2020 in the Central China (CC) urban in China. The results show that the urbanization process in the CC evolves from a rapidly growing state to a steady state with a slower rise. The ESV in CC increased from 2.75 trillion yuan in 2000 to 5.07 trillion yuan in 2020. There is an inverted U-shaped curve relationship between UI and ESV, the ESV sharply decrease when the urbanization index exceeded 0.5. Land urbanization and social urbanization has the greatest impact on ESV. There was an spatial heterogeneity in the hotspots of ecosystem services. The hot spots of ecosystem products services are distributed in the northeast of the study area, while regulation services and cultural services are distributed in the southwest of CC. The results can provide insights for enhancing urban sustainability in the CC region, as well other urban megaregion with similar characteristics throughout the world.