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.

     

Diversification of the urban forest—Can we afford to exclude exotic tree species?

Introduced tree species represent a substantial component of urban forests in cities all over the world. Yet there is controversy about the further use of introduced tree species. Many practice orientated publications,research papers and governmental websites in the fields of urban planning, urban forestry, and urban ecology argue for planting native species and avoiding introduced species. Such arguments for native-only species selection are also touted by environmental groups and the media. Consequently the debate has sometimes spiralled away from a sensible and rational platform where invasion risks and biodiversity loss are discussed, to a groundless and unreasonable argument where exotic species are generally considered incapable of providing ecosystem services. From a European perspective, we here aim to curate a set of necessary considerations for current and future discussions on native and non-native plant material in sustainable urban development. Using examples from Northern and Central Europe we illustrate that in some regions the catalogue of native tree species may be too limited to fulfil ecosystem services and resilience in harsh urban environments. A main message from our line of arguments is that we cannot afford to generally exclude non-native tree species from urban greening. If “native-only” approaches become incorporated in regional, national or international policy documents or legislation there is a risk that urban ecosystem resilience will be compromised, particularly in regions with extreme environmental conditions. Since both invasion risks and sizes of native species pools vary conspicuously at regional to continental scales we also argue to adapt urban policies on using non-native trees to regional contexts.     

Allerton Park 1983: the beginnings of a paradigm for landscape ecology?

In 1983, a group of incipient landscape ecologists met to discuss the nature and future directions for landscape ecology. The themes emerging from this conference—movement of materials, organisms, and energy through a landscape; the genesis of landscape patterns; the effects of landscape structure on the spread of disturbances; and the potential contributions of landscape ecology to resource management—established a foundation for the development of landscape ecology in North America over the following decades. I discuss these contributions in the light of where landscape ecology is today.

Spatial disparities in neighborhood public tree coverage: Do modes of transportation matter?

Urban green space has various environmental and ecological benefits, and uneven access to such amenities has drawn substantial attention from policy makers in developing sustainable community planning. In this study, we illustrate the spatial distribution of publicly owned and maintained trees in Edmonton, Canada and assess neighborhoods’ heterogeneous tree availability by using the container approach. Through spatial regression models, we further investigate the association of neighborhood public tree availability with socio-economic status (SES). We contribute to the existing literature by taking resident modes of transportation into consideration, in addition to many other commonly examined SES such as household income and ethnicity. Another unique contribution of this study is that we distinguish trees planted on different location types (i.e., boulevard, park, and buffer areas) when exploring the unequal coverage across neighborhoods and among different SES groups. Key results include: (1) a general examination without differentiating location types can lead to misleading results and thus provide inappropriate policy recommendations; (2) resident modes of transportation is a critical factor associated with a neighborhood’s public tree coverage; and (3) there exists evident spatial dependence on public tree availability between neighborhoods. The results from this study provide important information to better understand the issue and to allocate public resource (such as tree coverage) more efficiently and effectively to support sustainable community development.     

Is it common to be rare on the landscape? A test using a novel model system

Context

Understanding how rare species are distributed can be difficult due to heterogeneity between landscape units. Lack of statistical replication of landscapes can make it difficult to carry out testing. Model systems may be a solution.

Objectives

We test whether lichen thalli along the trunk of a tree are analogous to habitat patches in a kilometers-extent landscape and hence can function as a model system. This model system allows for increased statistical power. We use this system to test whether landscapes with rare species are different from those without.

Methods

We sampled macrolichen diversity along the trunk of 24 balsam fir trees in a stand on the Avalon Peninsula, Newfoundland, Canada, along with microclimate variables. We analysed difference in pattern by aspect and along the gradient of 1 m up the trunk as well as between trees containing the rare Erioderma pedicellatum and those without.

Results

We found no difference in total patch richness or abundance between the micro-landscapes. We found significantly consistent patterns in lichen patches along the trunk. These patterns were similar on the trees with the rare species. Lichen species richness did not differ between trees containing the rare species versus those that did not.

Conclusions

Lichen patch pattern is statistically similar between trees and as such, these can be considered as replicate landscape units. Thus, landscape ecologists can use micro-landscapes as model systems to conduct observational and manipulative experiments to test questions about spatial pattern and process, such as those concerning distribution of rare species.

     

Recreation shapes a “landscape of fear” for a threatened forest bird species in Central Europe

Predators can create a “landscape of fear” that influences the spatial distribution of their prey. Understanding whether human activity similarly affects the distribution of species beyond habitat suitability is crucial but difficult to assess for conservation managers. Here, we assessed the effect of recreation and forestry activity on a threatened forest-dwelling umbrella species, the Capercaillie (Tetrao urogallus). We followed the citizen science approach on the landscape scale in the Bohemian Forest. We analyzed species data non-invasively collected through intensive fieldwork by volunteers and assessed human activity in the entire study area by analyzing expert questionnaires. The study area extends over 119,000 ha and harbors one of the largest relict populations of this grouse species in Central European low mountain ranges. Our statistical models revealed a negative impact of recreational activities on the intensity of habitat use of the birds within suitable habitats, thereby pointing toward a landscape of fear. The influence of forestry activity, in contrast, was not clear. In comparison to existing regional tourism impact studies, we were able to elevate the examination to the landscape scale. Our results underlined the relevance of recreation in limiting the species’ habitat on an entire landscape and allow us to conclude that habitat managers should set aside well-defined zones without recreational activities to preserve the refuge of this umbrella species.     

Multifunctionality at what scale? A landscape multifunctionality assessment for the European Union under conditions of land use change

Context

The provision of multiple ecosystem services (ES) within a landscape is commonly referred to as landscape multifunctionality. Modifying landscapes to increase multifunctionality and reduce trade-offs with concurrent services bears the potential to enhance sustainability in human-dominated landscapes. Assessing landscape multifunctionality is thus crucial for land management and planning, but lack of a clear definition and operationalization of multifunctionality impedes comparisons of different study results.

Objectives

We want to address how elements of the study design affect results of multifunctionality assessments. Furthermore, we want to quantify future multifunctionality in the European Union (EU) and indicate the role of land use change and land use diversity on multifunctionality.

Methods

We analyzed diverging scenarios depicting land use change in the EU between 2000 and 2040 for their effects on landscape multifunctionality. We tested different multifunctionality indicators at various spatial scales based on the modelling of 12 ES and biodiversity indicators.

Results

Particularly the analysis scale determines the interpretation of landscape multifunctionality. Coldspots identified by different indicators are in higher agreement than hotspots. We could not confirm links between land use diversity and landscape multifunctionality. While, at EU scale, multifunctionality slightly increases in future scenarios, agricultural intensification and (peri-)urban growth pose large threats to multifunctional landscapes.

Conclusions

The choice of indicator and analysis scale strongly determine possible interpretations of the results. Rather than focusing on the impacts of land use change on multifunctionality, it is recommended to base land use policy on the impacts of location-specific change on ES supply and demands.

     

Addressing the interplay of poverty and the ecology of landscapes: a Grand Challenge Topic for landscape ecologists?

We argue for the landscape ecology community to adopt the study of poverty and the ecology of landscapes as a Grand Challenge Topic. We present five areas of possible research foci that we believe that landscape ecologists can join with other social and environmental scientists to increase scientific understanding of this pressing issue: (1) scale and poverty; (2) landscape structure and human well-being; (3) social and ecological processes linked to spatial patterns in landscapes; (4) conservation and poverty, and (5) applying the landscape ecologist’s toolkit. A brief set of recommendations for landscape ecologists is also presented. These include the need to utilize broad frameworks that integrate social and ecological variables, build capacity to do this kind of work through the development of strong collaborations of researchers in developed and developing countries, create databases in international locations where extreme poverty exists, and create a new generation of researchers capable of addressing this pressing social and environmental issue.     

Explaining host–parasitoid interactions at the landscape scale: a new approach for calibration and sensitivity analysis of complex spatio-temporal models

Landscape Ecology - Linking spatial pattern and process is a difficult task in landscape ecology because spatial patterns of populations result from complex factors such as individual traits, the...     

A landscape vulnerability framework for identifying integrated conservation and adaptation pathways to climate change: the case of Madagascar’s spiny forest

Context

Integrated conservation decision-making frameworks that help to design or adjust practices that are cognisant of environmental change and adaptation are urgently needed.

Objective

We demonstrate how a landscape vulnerability framework combining sensitivity, adaptive capacity, and exposure to climate change framed along two main axes of concern can help to identify potential strategies for conservation and adaptation decision-making, using a landscape in Madagascar’s spiny forest as a case-study.

Methods

To apply such a vulnerability landscape assessment, we inferred the sensitivity of habitats using temporal and spatial botanical data-sets, including the use of fossil pollen data and vegetation surveys. For understanding adaptive capacity, we analysed existing spatial maps (reflecting anthropogenic stressors) showing the degree of habitat connectivity, matrix quality and protected area coverage for the different habitats in the landscape. Lastly, for understanding exposures, we used climate change predictions in Madagascar, together with a digital elevation model.

Results

The fossil pollen data showed how sensitive arid-adapted species were to past climate changes, especially the conditions between 1000 and 500 cal yr BP. The spatial analysis then helped locate habitats on the two-dimensional axes of concern integrating sensitivity, adaptive capacity and climate change exposure. By identifying resistant, resilient, susceptible, and sensitive habitats to climate change in the landscape under study, we identify very different approaches to integrate conservation and adaptation strategies in contrasting habitats.

Conclusion

This framework, illustrated through a case study, provides easy guidance for identifying potential integrated conservation and adaptation strategies, taking into account aspects of climate vulnerability and conservation capacity.

     

How has the state-of-the-art for quantification of landscape pattern advanced in the twenty-first century?

Landscape Ecology - Landscape ecology was founded on the idea that there is a reciprocal relationship between spatial pattern and ecological processes. I provide a retrospective look at how the...     

Implications of forest type and land tenure diversity for the sustainability of ecosystem services provided by northern Amazonia’s multiple-use tree species

Context

As global landscapes continue to change, the sustainability of the ecosystem services they support are increasingly coming into question. In the rapidly changing neotropics, multiple-use plants epitomize sources of ecosystem services. To sustain the relationship that exists between such plants and human populations, a sound understanding of their well-being is required.

Objectives

Density data on multiple-use plants were compared across forest types and land tenure classes to understand the implications of these two spatial frames of reference for landscape sustainability.

Methods

The density of an aggregate sample of seventeen multiple-use and a sub-sample of five species were examined relative to forest type and land tenure class across fourteen Rupununi, Southern Guyana, study sites. The examination of plant density based on the two sample sizes was used to make inferences on how the two frames of reference may impact landscape sustainability.

Results

The mean density of the aggregate sample was highest in three of six forest types, but showed no statistical difference across land tenure classes. When individual species were considered mean densities showed no statistical difference across land tenure classes, but differences were observed for three species across forest types. Mean densities were highest in forest types within which swidden agriculture occurs and in the protected area where logging is prohibited.

Conclusions

Our findings suggested that in changing tropical landscapes plant species distribution can be predicted by forest types, but land tenure classes may provide clearer signals as to where a species well-being and hence ecosystem services may be compromised.

     

Do landscape and riverscape shape genetic patterns of the Neotropical otter,Lontra longicaudis,in eastern Mexico?

Context

Functional connectivity of semiaquatic species is poorly studied despite that freshwater ecosystems are amongst the most threatened worldwide due to habitat deterioration. The Neotropical otter, Lontra longicaudis, is a threatened species that represents a good model to evaluate the effect of landscape-riverscape features on genetic structure and gene flow of freshwater species.

Objectives

We aimed to assess the spatial genetic structure of L. longicaudis and to evaluate the landscape-riverscape attributes that shape its genetic structure and gene flow at local sites (habitat patches) and between sites (landscape matrix).

Methods

We conducted the study in three basins located in Veracruz, Mexico, which have a high degree of ecosystem deterioration. We used a non-invasive genetic sampling and a landscape genetics individual-based approach to test the effect stream hierarchical structure, isolation-by-distance, and isolation-by-resistance on genetic structure and gene flow.

Results

We found genetic structure that corresponded to the latitudinal and altitudinal heterogeneity of the landscape and riverscape, as well as to the hierarchical structure of the streams. Open areas and steep slopes were the variables affecting genetic structure at local sites, whereas areas with suitable habitat conditions, higher ecosystem integrity and larger streams enhanced gene flow between sites.

Conclusions

The landscape-riverscape characteristics that maintain functional connectivity of L. longicaudis differed between the upper, middle, and lower basins. Our results have important implications for the conservation of the species, including the maintenance of larger suitable areas in Actopan and the necessity to improve connectivity in Jamapa, through the establishment of biological corridors.

     

Global patterns of diversity in the urban forest: Is there evidence to support the 10/20/30 rule?

Diversity in the urban forest is important as it reduces risks from pests and diseases and from climate change and improves resilience in the supply of ecosystem services. To manage and improve diversity, there has been wide-spread acceptance of the 10/20/30 ‘rule of thumb’ proposed by Santamour, which states that municipal forests should comprise no more than 10% of any particular species, 20% of any one genus or 30% of any single family. While the implementation of targets based on Santamour's rule has contributed to a more diverse and resilient urban forest in many cities, there has been little empirical investigation of actual patterns of diversity occurring globally in different climates and land uses. In this study, we explored diversity and the relative abundance of the most common species, genus and family in 151 urban forest inventories from 108 different cities around the world. Observed patterns showed that relative abundance of the most common taxon was a good predictor of diversity and could be a useful measure of diversity for urban forest managers. Relative abundance of the most common taxon was much higher than the proposed benchmark at the species level, but comparable with proposed benchmarks at the genus and family level. Patterns varied by both climate and land use. Diversity was consistently lower in Continental climates and in streetscapes, and higher in Temperate climates and in urban forests that spanned multiple land uses. Further considerations in setting diversity benchmarks are discussed.     

Using a landscape ecological perspective to analyze regime shifts in social–ecological systems: a case study on grassland degradation of the Tibetan Plateau

Landscape Ecology - Landscape ecology thinking and social–ecological system (SES) thinking investigate human–environment relationships from the perspective of ‘space’ and...     

Dendroctonus micans populations on Picea pungens in the center of a non-outbreak region contain few pathogens,parasites or predators: A new threat for urban forests?

In reviewing the occurrence of the bark beetle Dendroctonus micans in the Czech Republic over the past 100 years, we found that D. micans has been detected at 80 localities with elevations ranging from 158 to 1350 m a.s.l. During 2011–2012, we recorded three local outbreaks on Picea pungens, two of which involved isolated trees in urban areas between houses (always on sites <1 ha). From these locally abundant populations, 125 adults, 5 pupae, and 73 larvae of D. micans were obtained and dissected. Among these dissected specimens, nematodes in the hemolymph were detected in only 5 adults and 11 larvae. No other parasites or pathogens were found in the D. micans specimens. Low numbers of the beetle Rhizophagus grandis, which is a specific predator of D. micans, were detected, and none contained parasites or pathogens. Locally D. micans could constitute a new limited threat to urban trees, including P. pungens, in the Czech Republic and Central Europe. Special attention should be given to solitary P. pungens trees; if D. micans is detected on these trees, defensive measures must be taken to protect uninfested trees in the vicinity.