Landscape Ecology最新文献

Context

The global impact of the SARS-CoV-2 pandemic has been uneven, with some regions experiencing significant excess mortality while others have been relatively unaffected. Yet factors which predict this variation remain enigmatic, particularly at large spatial scales.

Objectives

We aimed to uncover the key drivers of excess mortality across countries and regions to help understand the factors contributing to the varied impacts of the pandemic worldwide.

Methods

We used spatially explicit Bayesian models that integrate environmental, socio-demographic and endemic disease data at the country level to provide robust global estimates of excess SARS-CoV-2 mortality (P-scores) for the years 2020 and 2021.

Results

We find that urbanization, gross domestic product (GDP) and spatial patterns are strong predictors of excess mortality, with countries characterized by low GDP but high urbanization experiencing the highest levels of excess mortality. Intriguingly, we also observed that the prevalence of malaria and human immunodeficiency virus (HIV) are associated with country-level SARS-CoV-2 excess mortality in Africa and the Western Pacific, whereby countries with low HIV prevalence but high malaria prevalence tend to have lower levels of excess mortality. While these associations are correlative in nature at the macro-scale, they emphasize that patterns of endemic disease and socio-demographic factors are needed to understand the global dynamics of SARS-CoV-2.

Conclusions

Our study identifies factors associated with variation in excess mortality across countries, providing insights into why some were more impacted by the pandemic than others. By understanding these predictors, we can better inform global outbreak management strategies, such as targeting medical resources to highly urban countries with low GDP and high HIV prevalence to reduce mortality during future outbreaks.

Context

Urban forest soils represent significant reservoirs of biodiversity in cities. Retaining this diversity under urban land-use change requires understanding on how species richness, community assembly and uniqueness of species assemblages are related to local forest characteristics and surrounding landscape structure.

Objectives

Our aim was to assess the significance and relative importance of logging history, tree species composition and urbanization in shaping soil microbial communities across urban spruce-dominated forest landscapes. We investigated responses of microbial diversity from three complementary viewpoints: local diversity, community assembly patterns and community uniqueness.

Methods

We collected soil bacterial and fungal metabarcoding data from 73 spruce-dominated forest sites distributed in three urban centers across southern Finland. We related these data to measurements of logging intensity, tree species composition and degree of urbanization.

Results

Logging intensity, tree species composition and urbanization affected site-scale microbial diversity, but the effects varied between microbial groups. Only logging intensity had a significant imprint on microbial assembly, and this effect was restricted to bacteria. Relative uniqueness of microbial assemblages at the landscape-scale was coupled with the uniqueness of tree species composition in all microbial groups, and further affected by tree diversity in saprotrophic fungi and urbanization in ectomycorrhizal fungi.

Conclusions

In the context of urban spruce-dominated forests, locally diverse tree stands are not necessarily the same as those that contribute the most to landscape-scale diversity. Identifying and preserving contrasting tree stand structures, which support distinctive soil microbial assemblages, may be the winning strategy in maintaining a wide range of soil microbial diversity.

Context

Understanding habitat fragmentation is a critical concern for nature conservation and the focus of intense debate in landscape ecology. Resolving the uncertainty around the effects of habitat fragmentation on biodiversity remains an ongoing challenge that requires the successful delineation of multiple patch-landscape interactions.

Objectives

We carried out a regional analysis on species richness of woodland mammals to determine the relative influence of structural, compositional and functional characteristics related to woodland habitat across different land-cover gradients.

Methods

We calculated the Edge-weighted Habitat Index, an area-weighted measure of functional connectivity that incorporates a mechanistic estimate of edge-effects, for interior woodland habitat. We compared its influence on mammalian species richness to that of increasing edge and patch density, landscape diversity, and a habitat-only model, in different contexts of matrix hostility across Northern England in the UK.

Results

Our results demonstrate the relevance of alternative drivers of species richness resulting from patch-landscape interactions across gradients of matrix hostility. Evidence is provided for positive and negative effects of increasing structural (edge density), functional (connected interior habitat) and compositional (landscape diversity) attributes, varying according to matrix type and intensity. Results were sensitive to dominant land-cover types in the matrix and the scale of observation.

Conclusion

This study provides new insights into fragmentation effects on biodiversity and clarifies assumptions around the relative influence of structural, compositional and functional habitat characteristics on landscape-level species richness. We highlight the presence of thresholds, related to matrix hostility, that determine alternative drivers of species richness in woodland mammals. These drivers, and related thresholds, were sensitive to the scale of observation and landscape context. Landscape decisions aimed at promoting biodiversity should consider sources of matrix hostility and homogeneity at scales relevant to ecological processes of interest.

Context

The alfalfa weevil Hypera postica Gyllenhal (Coleoptera: Curculionidae) is one of the most destructive pests of alfalfa worldwide. Both local and landscape-scale factors can significantly influence crop pests, natural enemies, and the effectiveness of biological control services, but the relative influence of these factors is unclear.

Objectives

We investigated the influence of the local variables and surrounding landscape composition and configuration on the abundance of alfalfa weevil, and on the abundance and parasitism rates of its larval parasitoids, Bathyplectes spp.

Methods

We sampled 65 commercial alfalfa fields along the Ebro Basin, Spain, over a period of 3 years, recording the field characteristics and landscape structure at three buffer radii of 250, 500 and 1000 m from the center of each field.

Results

The abundance of weevil larvae was positively associated with the field perimeter and with the uncut alfalfa surrounding the pipes of the sprinkler irrigation system, but only one configuration variable was positively correlated: the alfalfa edge density. No local characteristics or landscape structures were associated with the abundance of adult weevils. The abundance of Bathyplectes spp. adults was positively associated to local factors such as the densities of alfalfa weevils and aphids. Few landscape structure variables, such as alfalfa edge density and Simpson’s Diversity Index, had explanatory value only at 250 m buffer radius. The rate of larval parasitism was affected by local variables, such as alfalfa weevil abundance and field age.

Conclusion

Our results provide, for the first time in the Mediterranean region and Europe, evidence of the relative importance of landscape structure and local factors on the abundance of the alfalfa weevil and its larval parasitoids, Bathyplectes spp. The strongest influences were based on local characteristics.

Context

Sustainable development in coastal zones faces escalating flood risk in the context of climate change and urbanization, and the rapid urban growth in flood zones has been one of the key drivers. Therefore, understanding the Urban Exposure to Flooding (UEF) and its future scenarios is important in coastal zones.

Objectives

The objectives of this study were: (1) to assess the future dynamics of UEFs in China's coastal zones, and (2) to identify a sustainable way of urban planning in controlling the growth of UEFs.

Methods

Future UEFs in coastal China were assessed during 2020–2050 by combining urban expansion model, scenario analysis, and flood exposure assessment. Alternative scenarios were considered of shared socioeconomic pathways (SSPs), representative concentration pathways (RCPs), strategies of urban planning.

Results

The results show that the 1000-year flood UEFs along coastal China was expected to grow under SSP2-RCP4.5 from 9,879 km² in 2020 to 13,424 (12,997–13,981) km² in 2050, representing an increment of 35.88% (31.56%–41.52%). Alternatively, the strategy of sustainable development planning could reduce the newly added UEF by 16.98% (15.63%–18.67%) in a 1000-year flood scenario.

Conclusions

The findings proved that the ways of urban growth matters in terms of affecting food exposure and risk and flood risk should be incorporated into urban planning for a sustainable landscape. The study could offer methodology and support for sustainable development strategies in reducing future urban flood risk.

Context

Typical landscape-scale studies comprise the delimitation of landscapes followed by the calculation of one or more landscape metrics. Performing an analysis at multiple spatial scales is often required, occasionally followed by the selection of a particular scale according to the response variable of interest. More complex research goals might require a thorough inspection of landscapes, plus a selection of landscapes that would fulfill certain conditions regarding their landscape metrics. These tasks can usually be programmatically challenging, especially if multiple spatial scales are being analyzed.

Objectives

The R package multilandr builds on several spatial-oriented R packages to provide a toolbox to develop and inspect multi-scale landscapes based on simple spatial inputs.

Methods and results

The package delivers functions to calculate metrics within a multi-scale framework. Also, it provides several utility functions to visualize correlations between metrics, filter landscapes that fulfill certain predefined conditions or select a wide-range gradient of landscapes for a given metric, among other useful tasks. This paper introduces the functionality of multilandr through a step-by-step instruction guide and case studies.

Conclusions

The R package multilandr provides a set of functions to facilitate typical methodological workflow of landscape-scale studies in the R environment, for both beginner and expert R users. It provides the functionality to perform a systematic filtering and selection of landscapes according to a given experimental design. The package is especially programmed to develop multi-scale designs but is also useful for the calculation of metrics of a set of landscapes from any GIS-related project.

Context

As complementary terrestrial and aquatic habitats are pulled apart by environmental change, animals will have to adjust their behaviours to successfully track their fundamental niches. We introduce a novel example of how climate change impacts can drive separation between complementary foraging and breeding habitats in seabirds.

Objectives

We evaluated how Black Noddies (Anous minutus) modified their movement behaviour across the seascape to access complementary habitat types during a period of local food scarcity; and whether this influenced their breeding success.

Methods

We quantified characteristics of foraging behaviour relating to energy consumption (time, distance and area covered) over four breeding seasons for Black Noddies (A. minutus) and compared favourable years (2019, 2020 and 2021) to an unfavourable year (2022). We also quantified and compared chick health and survival rates over the same period.

Results

In 2022, severe reduction in local food abundance on Heron Island led breeding Black Noddies to forage further by an order of magnitude, utilizing a remote wooded island (Bushy Islet) as an overnight roosting location. This was a novel and completely unexpected response to the altered environmental conditions. At the same time, 2022 saw significant increases in chick mortality and decreases in chick health compared to other years.

Conclusions

We show how a growing mismatch between nesting, roosting, and foraging sites pushed individuals in a breeding tropical seabird population to extend their foraging range by an order of magnitude, with direct negative consequences for juveniles. Our findings highlight the need to explicitly consider habitat complementation in land- and seascape conservation initiatives and planning.

Context

Human disturbance has transformed ecosystems globally, yet studies of the ecological impact of landscape modification are often confounded. Non-random patterns of land clearing cause differing vegetation types and soil productivity between fragments in modified landscapes and reference areas—like national parks—with which they are compared.

Objectives

We sought to explore the influence of land modification on herpetofauna and small mammal communities using multiple biodiversity measures—species richness and diversity, individual species abundance, and community composition. We also aimed to investigate the role of traits such as diet, habitat breadth, and litter size in moderating species responses to land modification.

Methods

We established 100 sampling sites to survey herpetofauna and small mammals in 11 fragments in an agricultural landscape compared to 11 ecologically equivalent ‘pseudo-fragments’ in a nearby national park in south-eastern Australia. We selected pairs of fragments and pseudo-fragments of the same size and vegetation type, and used identical survey methods to sample pairs simultaneously, thereby controlling for numerous confounding factors, such as differing vegetation type, weather, and survey effort.

Results

Species richness and diversity were similar between fragments and pseudo-fragments. Despite this, we found community composition differed markedly—driven by the varying responses of individual species—indicating a shift in fauna communities associated with land modification. Fossorial habit, omnivorous diet, and broad habitat requirements led to higher abundance in fragments whilst arboreality, carnivorous diet, and narrow habitat requirements led to higher abundance in pseudo-fragments.

Conclusions

Although fragments hold similar numbers of species to continuous areas, they contain distinct and novel communities, and sustain high abundances of some species. These diverse communities are dominated by native species, including threatened species, and their distinctive composition is shaped by traits conducive to persistence amidst land modification. These novel communities may provide a reservoir of resilience in the face of environmental change and should be viewed as complementary to conservation areas.

Context

Reinforcement of agrobiodiversity in peri-urban areas requires a landscape lens. Relationships between land use composition and indicators of ecosystem services can depend on weather conditions and differ between regions.

Objectives

In this study we present new empirical data on relationships between landscape composition and indicators of regulating and provisioning agroecosystem services. Furthermore, we check if these data are consistent between two different ecoregions and different years.

Methods

We apply an innovative methodology in a research landscape in the province of Antwerp (Flanders, Belgium) in 2021 with 1 m²-garden as phytometers along a landscape compositional gradient. Landscape composition at different scales is used as explanatory variable for microclimate variation, arthropod activity, leaf herbivory and crop yield in the 1 m²-gardens. Results are compared to an identical experiment in another ecoregion in East Flanders in 2018, 2019.

Results

We found that the proportion of built-up areas is negatively related to local agroecosystem functioning. High-value herbaceous vegetation (e.g. extensive grasslands) promotes the activity of predators and high green vegetation buffers soil moisture and temperature variation, during dry and warm periods. Comparison between cases indicates that there is more consistency in the response of predatory invertebrates to the landscape composition than in the response of pollinators. The buffering effect of high green vegetation in the landscape increases when temperature and drought extremes occur.

Conclusions

The extent of high green vegetation can be enhanced at landscape level to maximise their ability to buffer extreme weather conditions. In peri-urban areas we should avoid further urban sprawl into the rural matrix and promote high-value herbaceous vegetation.

Context

Land use history of urban forests impacts present-day soil structure, vegetation, and ecosystem function, yet is rarely documented in a way accessible to planners and land managers.

Objectives

To (1) summarize historical land cover of present-day forest patches in Baltimore, MD, USA across land ownership categories and (2) determine whether social-ecological characteristics vary by historical land cover trajectory.

Methods

Using land cover classification derived from 1927 and 1953 aerial imagery, we summarized present-day forest cover by three land cover sequence classes: (1) Persistent forest that has remained forested since 1927, (2) Successional forest previously cleared for non-forest vegetation (including agriculture) that has since reforested, or (3) Converted forest that has regrown on previously developed areas. We then assessed present-day ownership and average canopy height of forest patches by land cover sequence class.

Results

More than half of Baltimore City’s forest has persisted since at least 1927, 72% since 1953. About 30% has succeeded from non-forest vegetation during the past century, while 15% has reverted from previous development. A large proportion of forest converted from previous development is currently privately owned, whereas persistent and successional forest are more likely municipally-owned. Successional forest occurred on larger average parcels with the fewest number of distinct property owners per patch. Average tree canopy height was significantly greater in patches of persistent forest (mean = 18.1 m) compared to canopy height in successional and converted forest patches (16.6 m and 16.9 m, respectively).

Conclusions

Historical context is often absent from urban landscape ecology but provides information that can inform management approaches and conservation priorities with limited resources for sustaining urban natural resources. Using historical landscape analysis, urban forest patches could be further prioritized for protection by their age class and associated ecosystem characteristics.