Identifying future research needs in landscape genetics: where to from here?

Landscape genetics is an emerging interdisciplinary field that combines methods and concepts from population genetics, landscape ecology, and spatial statistics. The interest in landscape genetics is steadily increasing, and the field is evolving rapidly. We here outline four major challenges for future landscape genetic research that were identified during an international landscape genetics workshop. These challenges include (1) the identification of appropriate spatial and temporal scales; (2) current analytical limitations; (3) the expansion of the current focus in landscape genetics; and (4) interdisciplinary communication and education. Addressing these research challenges will greatly improve landscape genetic applications, and positively contribute to the future growth of this promising field. Participants of the Landscape Genetics Research Agenda Workshop, held at the 2007 World Congress of the International Association of Landscape Ecologists (IALE), in Wageningen, The Netherlands: Paul Arens, Pascal Campagne, Virginia H. Dale, Alfredo G. Nicieza, Marinus J. M. Smulders, Edoardo Tedesco, Hongfang Wang, Tzeidle Wasserman.     

Landscape contrast: a solution to hidden assumptions in the metacommunity concept?

The metacommunity concept provides a spatial perspective on community dynamics, and the landscape provides the physical template for a metacommunity. Several aspects of landscape heterogeneity, such as landscape diversity and composition, and characteristics of the matrix between habitat patches such as habitat connectivity, and geometry of habitat patches, may moderate metacommunity processes. These aspects of landscape heterogeneity are rarely considered explicitly in the metacommunity discussion, however. We propose landscape contrast (i.e., the average dissimilarity in habitat quality between neighboring patches) as a key dimension of landscape heterogeneity. The concept of landscape contrast unifies discrete and continuous landscape representations (homogeneous, gradient, mosaic and binary) and offers a means to integrate landscape heterogeneity in the metacommunity concept. Landscape contrast as perceived by the organisms affects several fundamental metacommunity processes and may thus constrain which metacommunity models may be observed. In a review of empirical metacommunity studies (n = 123), only 22 % of studies were explicit about their underlying landscape model assumptions, with striking differences among taxonomic groups. The assumed landscape model constrained, but did not determine, metacommunity models. Integration and explicit investigation of landscape contrast effects in metacommunity studies are likely to advance ecological theory and facilitate its application to real-world conservation problems.     

The ecosystem services concept: a new Esperanto to facilitate participatory planning processes?

Landscape Ecology - Several case studies investigated the role of ecosystem services in participatory planning processes. However, no systematic study exists that cuts across a large number of...     

Landscape composition or configuration: which contributes more to catchment hydrological flows and variations?

Landscape Ecology - Landscape composition and configuration determine the generation and exchange of water flows among different landscape patches and may affect catchment hydrological flows and...     

Taking a moment to measure networks—an approach to species conservation

Landscape Ecology - Network-theoretic tools contribute to understanding real-world system dynamics, such as species survival or spread. Network visualization helps illustrate structural...     

Pocket parks in a compact city: how do birds respond to increasing residential density?

The desire to improve urban sustainability is motivating many city planners to adopt growth strategies that increase residential density, leading to substantial changes to urban landscapes. What effect this change will have on biodiversity remains unclear, but it is expected that the role of public greenspace in providing wildlife habitat will become critical. We explored the role of urban “pocket parks” as habitat for birds, and how this role changed with increasing residential density in the surrounding neighbourhood. We found that parks in neighbourhoods with high levels of public greenspace (corresponding to less residential land) supported more bird species and individuals overall, and more woodland-dependent species, insectivores and hollow-nesters. Total greenspace area was more important (included in the best ranked models for all bird responses) than the configuration (number, average size and connectivity) of greenspace patches. The majority of species were common suburban birds, indicating that species we assume are tolerant to urban areas will be negatively affected by increasing residential density. Parks form part of an interconnected network of urban open space. For parks to continue to support a diverse native bird community, the network must be viewed, managed, and maintained in its entirety. We suggest three key management actions to improve the bird diversity values of urban greenspaces in compact cities: (1) Increase urban greenspace cover in residential neighbourhoods. (2) Increase vegetation structure in greenspace. (3) Encourage homeowners to plant trees and shrubs.     

How is setting preference related to intention to engage in forest recreation activities?

Urban forests provide opportunities for outdoor recreation to many people. Knowledge of the motives for visiting forests is needed for the planning and management of these forests. Since forests are used for a diverse set of recreational activities, however, the motives for different activities are multifaceted. To explore recreational motives, this scene preference study conducted in Sweden examined relations between setting evaluations (i.e., mystery, legibility, valence, and activation), setting preference, general forest perceptions, and intention to engage in forest activities. Two alternative models were examined in relation to five different activities: walking, going on outings, exercising, picking berries or mushrooms, and studying plants and animals. Results revealed that preference mediated between setting evaluations and intention to go on outings, whereas setting evaluations were direct predictors of intention to walk and exercise. However, the models did not describe antecedents of intention to pick berries or mushrooms, or to study plants and animals, satisfactorily. In addition, general forest perceptions, particularly emphasising the restorative qualities of forests, were important for intention to engage in all the examined recreation activities. Results are discussed in relation to landscape preference research and attitude-behaviour theory. In addition, practical implications for encouraging forest recreation are highlighted.     

Thresholds of landscape change: a new tool to manage green infrastructure and social–economic development

An understanding of how and where a landscape can be improved with green infrastructure is important for the development of land-use policies. However, it is still a big challenge to manage landscapes due to a lack of condition-based diagnosis and consistent conflicts with social–economic interests. The purpose of this study is to identify the thresholds of landscape change and to explore new reference lines of policy decision-making for balancing social–economic development and green infrastructure management. Five different landscape types and their thresholds of landscape change were identified using parametric and piecewise linear models in the district of Haidian, Beijing, PR China, and their changes and social–economic drivers were analyzed with principal component analysis and a stepwise linear regression model for the time period 1991–2010. It is shown that different thresholds of different landscapes do exist and can be identified by the area of their key elements of green infrastructure. Integrating these thresholds into a social–economic context, it is shown where and how social–economic variables can be manipulated quantitatively to achieve development targets with respect to green infrastructure in individual towns and the entire district. Green infrastructure can be managed by changing just a small proportion of social–economic investment. This paper provides a useful tool to achieve a sustainable development by balancing green infrastructure with social–economic interests.     

A bird’s eye view: using circuit theory to study urban landscape connectivity for birds

Context

Connectivity is fundamental to understanding how landscape form influences ecological function. However, uncertainties persist due to the difficulty and expense of gathering empirical data to drive or to validate connectivity models, especially in urban areas, where relationships are multifaceted and the habitat matrix cannot be considered to be binary.

Objectives

This research used circuit theory to model urban bird flows (i.e. ‘current’), and compared results to observed abundance. The aims were to explore the ability of this approach to predict wildlife flows and to test relationships between modelled connectivity and variation in abundance.

Methods

Circuitscape was used to model functional connectivity in Bedford, Luton/Dunstable, and Milton Keynes, UK, for great tits (Parus major) and blue tits (Cyanistes caeruleus), drawing parameters from published studies of woodland bird flows in urban environments. Model performance was then tested against observed abundance data.

Results

Modelled current showed a weak yet positive agreement with combined abundance for P. major and C. caeruleus. Weaker correlations were found for other woodland species, suggesting the approach may be expandable if re-parameterised.

Conclusions

Trees provide suitable habitat for urban woodland bird species, but their location in large, contiguous patches and corridors along barriers also facilitates connectivity networks throughout the urban matrix. Urban connectivity studies are well-served by the advantages of circuit theory approaches, and benefit from the empirical study of wildlife flows in these landscapes to parameterise this type of modelling more explicitly. Such results can prove informative and beneficial in designing urban green space and new developments.

     

Inequity in nature’s contributions to people in Ōtautahi/ Christchurch: A low-density post-earthquake city

Nature’s contributions to people (NCP) include the regulating, material, and non-material benefits of urban vegetation that improve well-being. It is increasingly important to plan cities that provide multiple types of NCP equitably to all residents of the city. However, due to historical legacies and planning policies, it is common for the most socially and economically vulnerable urban residents to suffer reduced access to the benefits of urban ecosystems. Previous studies of urban NCP have drawn attention to inequity in one or several types of NCP, but few have analysed a broad range. Here we analysed inequity in nine diverse forms of urban NCP across an index of economic and social vulnerability designed specifically to characterise vulnerability to environmental pressures. Furthermore, we used spatial analysis to map co-variance in vulnerability and a composite indicator of urban NCP, thus highlighting priority regions for future investments in green infrastructure. We applied this approach to the city of Christchurch/ Ōtautahi in Aotearoa/ New Zealand, which provides a valuable case study due to its multicultural population and recent history of widespread damage and regeneration following the 2011 earthquake. Overall, the distribution of urban NCP is inequitable to the disadvantage of more vulnerable residents. Residents of more vulnerable neighbourhoods experienced reduced provision of carbon stock, runoff retention, air quality enhancement, shade, educational green space, public outdoor space accessibility, private green space, and bird biodiversity contributions. Conversely, more vulnerable neighbourhoods had greater provision of erosion mitigation (although negligible in magnitude). The wide range of indicators used and assessed in response to vulnerability, coupled with an assessment of the type of vegetation cover (i.e. grass, tall trees) provides greater insights into how inequities in urban NCP can be addressed in future redevelopment.     

From monocultures to mixed-species forests: is tree diversity key for providing ecosystem services at the landscape scale?

Context

Converting monocultures to mixed-species stands is thought to be a promising approach to increase forest productivity and resilience, while additionally providing other ecosystem goods and services (EGS). However, the importance of tree species composition and structure remains unclear, particularly beyond the stand scale due to the difficulty of conducting comprehensive, long-term experiments.

Objectives

To compare the ability of different tree species mixtures to provide various EGS at the landscape scale.

Methods

We used a dynamic forest landscape model to simulate all possible combinations of dominant tree species for two landscapes; a high-elevation alpine region (Dischma valley, Switzerland) and a lowland valley (Mt. Feldberg, Germany). We evaluated multiple EGS, including protection from gravitational hazards, aboveground biomass, and habitat quality, and examined trade-offs and synergies between them.

Results

Mixed-species forests were usually better in providing multiple EGS, although monocultures were often best for single EGS. The simulation results also demonstrated how changing environmental conditions along an elevational gradient had a strong impact on the structure of different species combinations and therefore on the provisioning of EGS.

Conclusion

Tree species diversity alone is not a good predictor of multifunctionality. Mixtures should be selected based on local environmental conditions, complementary functional traits, and the ability to provide the EGS of interest. Although our work focused on current climatic conditions, we discuss how the modelling framework could be employed to consider the impacts of climate change and disturbances to improve our understanding of how mixed-species stands could be used to cope with these challenges.

     

Changes in visits to green spaces due to the COVID-19 pandemic: Focusing on the proportion of repeat visitors and the distances between green spaces and visitors’ places of residences

Through a quantitative approach, this study aimed to clarify the changes in the number of visitors and visits to green spaces according to green space type before and after the COVID-19 pandemic. We explored the changes in the proportion of repeat visitors and the distance between green spaces and visitors’ places of residence. We used KDDI Location Analyzer, which performs novel analysis using mobile phone GPS and census data. The study area included 10 target sites (urban parks and nature trails in the backcountry) located in the Sapporo metropolitan area in Japan. The survey period included snow-free seasons from 2019 to 2021, and 2019 was considered the period “before the pandemic.” The results revealed that the number of visits during the pandemic increased compared with those before the pandemic, except for those of urban parks near the city center. In 2020, the proportion of repeat visitors increased for all 10 target sites. In addition, since the outbreak of the pandemic, distances between all urban parks and visitors’ residences decreased. The same trend was observed for nature trails in the backcountry close to the city center. These findings indicate a generally decreasing trend in the number of visits to green spaces as many people have been refraining from visiting the site since the outbreak of the pandemic. Contrastingly, the number of visits by repeat visitors who reside close to the target sites has increased in some cases, which compensated for the general decreases.     

Investigations on Chlorosis of Fruit Trees.: III.—A Chlorosis of Plums Due to Potassium Deficiency.

Summary

Grafting is a suitable method to control soil-borne diseases in melon (Cucumis melo L.) crops. To date, several Cucurbita species and their inter-specific hybrids have been tested as rootstocks. However, graft-scion incompatibility and lower fruit quality have prevented their commercial use. The wild accession ‘Pat 81’ ssp. agrestis of C. melo is highly resistant to Monosporascus cannonballus Pollack et Uecker root rot, and develops a root system that is more suitable to withstand infested soils than that of cultivated melon. The potential of ‘Pat 81’ as a rootstock for melons (e.g., ‘Piel de Sapo’ type, C. melo ssp. melo) compared with the popular rootstock ‘RS 841’ (Cucurbita maxima Cucurbita moschata) has been evaluated here. The response of grafted plants to Monosporascus root rot disease, and rootstock effects on plant performance and fruit quality have been investigated using both classical methods and modern technologies (e.g., root image analysis and real-time PCR). The results indicate that, during infection, the root system of ‘Pat 81’ adapts to the needs of the aerial part of the ‘Piel de Sapo’ scion, displays a high level of resistance to M. cannonballus (similar to ‘RS 841’), and provides the plant with more healthy roots, with a higher root/vine biomass ratio compared with non-grafted ‘Piel de Sapo’. In addition, ‘Pat 81’ rootstock retains its favourable root structure (i.e., larger total length and root area) to withstand soil stress. In healthy soils, ‘Pat 81’ rootstocks had less effect on fruit quality than ‘RS 841’, leading to a lower percentage of non-marketable products. The high resistance of ‘Pat 81’, and its reduced effect on fruit quality, point to it as a good rootstock for the grafting of melons to resist M. Cannonballus infested soils.     

From the Mediterranean Sea to Madagascar: Are there ecological barriers for the long-distance migrant Eleonora’s falcon?

We examined the connection between landscape characteristics and behaviour of a long-distance migratory raptor. Our main goal was to test whether long-distance migratory birds adjust their migration programme according to the different characteristics of the habitats crossed during the journey with special emphasis in the so-called “ecological barriers”, inhospitable environments such as deserts, ice fields, seas and mountain ranges, where the opportunities to fulfil energy requirements are low or absent and environmental factors could be extremely severe. To this end, 11 Eleonora’s falcons were tracked by satellite telemetry in their ca. 9000 km autumn migration route from colonies located in Western Mediterranean to their wintering grounds in Madagascar during 2007 and 2008. Our results show that Eleonora’s falcons migrated during day and night-time, adjusting migration speed and daily distance in relation to the crossed region. Unlike other migrant species, Eleonora’s falcons did not avoid ecological barriers by making unnecessary detours around them or converging on narrow corridors. Nocturnal migration and higher daily distances were observed when flying across the Sahara Desert and the Mozambique Channel. The circadian pattern of activity budget shows that Eleonora’s falcon relies on an internal navigation mechanism that works during both day and night. Finally, our results suggest that the Sahara is an ecological barrier not only for passerines but also for raptors migrating within the Palaearctic-African flyway.     

Vegetation cover within and around schools in Santiago de Chile: Are schools helping to mitigate urban vegetation inequalities?

Vegetation within cities is key for urban sustainability, as it provides several ecosystem services positively influencing the urban quality of life. However, urban vegetation is often unevenly distributed within cities, typically concentrating the large proportion of vegetated areas in more affluent neighborhoods. Thus, developing strategies for reducing urban vegetation inequalities is fundamental to fostering more sustainable cities. Since schools are widely distributed in urban areas, they could be key for decreasing vegetation inequalities, in particular, if schools’ precincts in lower-income areas are managed to contain high levels of vegetation. Nevertheless, studies analyzing the potential role of schools in ameliorating vegetation inequalities in cities are largely missing in the literature. In this study we use remote sensing techniques to estimate the vegetation cover of 1579 schools and their surrounding areas in Santiago-Chile, aiming to evaluate whether vegetation within schools is helping to mitigate the high levels of vegetation inequalities characteristic of this city. We performed the analysis for public, subsidized and private schools, for the whole city and each of the 34 municipalities comprising the city. Our results show that schools are not helping to mitigate vegetation inequalities, but they tend to replicate the unequal distribution of vegetation within Santiago. This pattern holds whether the analysis is made for all schools or each of the three school types independently, and is also a prevalent pattern when the assessment is performed at the municipal level. Private schools, usually located in greener more affluent areas of the city, have significant larger proportion of vegetation, revealing that high-income students do not only live in greener neighborhoods but also have access to greener schools. These results reveal how deeply rooted in some cities are vegetation inequalities, and the urgency of modifying public policies related to how vegetation within schools is funded, planned and managed.