Restoring the iconic Ulmus americana to urban landscapes: Early tree growth responds to aboveground conditions

Native trees provide a range of benefits, from supporting native wildlife to climate regulation, and many urban natural resource managers prioritize native tree planting and restoration. Ulmus americana (American elm) was once widely planted in American cities but has been decimated by Dutch elm disease (DED; Ophiostoma ulmi). Our study evaluated U. americana establishment and growth across urban landscapes. We planted ramets from three DED-tolerant U. americana genotypes (RV16, RV474, and Sunfield) along an urbanization gradient in Newark, DE and Philadelphia, PA, and assessed physiological and morphological responses. We analyzed how U. americana clone growth, chlorophyll fluorescence, and foliar chemistry relate to impervious surface area, ozone (O₃) concentrations, and soil characteristics. The one-year post planting mortality rate was low (4%) demonstrating these elms can withstand urban environmental conditions when provided ample water supply and protection from deer. As expected, the elms differed in growth rate, chlorophyll fluorescence, and foliar chemistry between the cities. Elms planted in Philadelphia had greater photosynthetic capacity in July (F_v/F_m = 0.76) and September (F_v/F_m = 0.75), while Newark elms had greater photosynthetic capacity in August (F_v/F_m = 0.78). Depleted foliar δ¹³C signatures in Philadelphia suggest elms are experiencing greater fossil-fuel derived atmospheric CO₂ than in Newark, possibly contributing to the greater growth rates observed in Philadelphia compared to Newark. Enriched foliar δ¹⁵N and greater foliar %N in Philadelphia clones suggest they are experiencing greater N deposition from NO_x-derived sources compared to Newark clones. Clones growing in Philadelphia had greater foliar nutrient concentrations despite growing in soils with greater heavy metal concentrations. These foliar-soil chemistry patterns suggest that clones growing in Philadelphia respond positively to urban environmental conditions in a large city, whereas clones growing in Newark may be experiencing N limitation in the first year of growth after planting.     

Conservation planning in a fire-prone Mediterranean region: threats and opportunities for bird species

In response to the processes threatening biodiversity such as habitat loss, effective selection of priority conservation areas is required. However, reserve selection methods usually ignore the drivers of future habitat changes, thus compromising the effectiveness of conservation. In this work, we formulated an approach to explicitly quantify the impact of fire on conservation areas, considering such disturbance as a driver of land-cover changes. The estimated fire impact was integrated as a constraint in the reserve selection process to tackle the likely threats or opportunities that fire disturbance might cause to the targeted species depending on their habitat requirements. In this way, we selected conservation areas in a fire-prone Mediterranean region for two bird assemblages: forest and open-habitat species. Differences in conservation areas selected before and after integrating the impact of fire in the reserve selection process were assessed. Integration of fire impact for forest species moved preferences towards areas that were less prone to burn. However, a larger area was required to achieve the same conservation goals. Conversely, integration of fire impacts for open-habitat species shifted preferences towards conservation areas in locations where the persistence of their required habitat is more likely (i.e. shrublands). In other words, we prioritized the conservation of not only the current distribution of open-habitat birds, but also the disturbance process (i.e. fire) that favours their preferred habitat and distributions in the long term. Finally, this work emphasizes the need to consider the opposing potential impacts of wildfires on species for an effective conservation planning.     

Ecosystem services in changing landscapes: An introduction

The concept of ecosystem services from landscapes is rapidly gaining momentum as a language to communicate values and benefits to scientists and lay alike. Landscape ecology has an enormous contribution to make to this field, and one could argue, uniquely so. Tools developed or adapted for landscape ecology are being increasingly used to assist with the quantification, modelling, mapping, and valuing of ecosystem services. Several of these tools and methods encased therein are described among the eleven papers presented in this special issue, and their application has the potential to facilitate the management and promotion of services within ecosystems. Papers are associated with each of the four key categories of services that ecosystems provide to humans: supporting, provisioning, regulating, and cultural. The papers represent work conducted in eleven different countries, especially from South America. Each carries a unique approach to address a particular question pertaining to a particular set of ecosystem services. These studies are designed to inform and improve the economic, environmental and social values of the ecosystem services. This knowledge should help to develop new management alternatives for sustaining and planning ecosystems and the services they provide at different scales in space and time. We believe that these papers will create interest and inform management of some potential methods to evaluate ecosystem services at the landscape level with an integrative approach, offering new tools for management and conservation.     

Aesthetic landscapes: an emergent component in sustaining societies

A revival in the concept of sustainability is appreciated as Earth’s human population continues to increase and its related global concerns in disease ecology, energy resource management, environmental literacy, food production, genetic diversity, and landscape vitality continue to magnify. Sustain is defined within this paper as to keep in existence or to supply with resources or necessities to prevent from falling below a given threshold of health or vitality. Barrett et al. (Bioscience 47:531–535, 1997) illustrated how seven (7) processes (behaviour, development, diversity, energetics, evolution, integration, regulation) transcend eleven (11) levels of ecological organization, ranging from the ecosphere to the cellular. Comprehension of how these processes transcend all levels of ecological organization allow programs and initiatives (e.g. preserving biotic diversity) to be defined by informed incentive, rather than regulatory mandate, within societal systems. We describe how the integration of an eighth transcending process—aesthetics—is essential in the approach to and managing of market and nonmarket capital necessary in sustaining societies.     

Species absence in developed landscapes: an experimental evaluation

Context

Conversion of landscapes is widely associated with loss of biodiversity. While there are several competing hypotheses for the local extinction of species in developed landscapes, experimental approaches are seldom applied to elucidating mechanisms.

Objectives

In this study, we focus on the habitat degradation hypothesis and predict that poor quality of relictual wetlands in developed landscapes contributes to the absence of wood frogs (Rana sylvatica = Lithobates sylvaticus) by decreasing their performance.

Methods

In a translocation experiment, we reared wood frog larvae within enclosures in seven ponds where they naturally occur and in five ponds in developed landscapes where they are absent. Premature pond drying precluded assessing performance in one present pond and one absent pond.

Results

Absent ponds were surrounded by upland buffers dominated by developed land covers while ponds with wood frog breeding populations were surrounded primarily by intact forest. Ponds were largely similar in their attributes. Survival and growth rate did not differ between pond types. Development tended to be slightly more rapid in some absent ponds perhaps related to higher water temperatures.

Conclusions

Despite the highly altered landscapes surrounding them, we find no evidence that absent wetlands provide inferior habitat for wood frog larval recruitment. Performance in absent ponds matched or exceeded that observed in present ponds implying that absence of this species may stem from influences mediated by the upland landscape. These results provide a caution to the typically unexamined presumption that relictual habitats in developed landscapes are degraded in their utility for wildlife.

     

Immersive landscapes: modelling ecosystem reference conditions in virtual reality

Landscape Ecology - Understanding the variability and dynamics of ecosystems, as well as their responses to climate or land use change, is challenging for policy makers and natural resource...     

Forest gradient response in Sierran landscapes: the physical template

Vegetation pattern on landscapes is the manifestation of physical gradients, biotic response to these gradients, and disturbances. Here we focus on the physical template as it governs the distribution of mixed-conifer forests in California's Sierra Nevada. We extended a forest simulation model to examine montane environmental gradients, emphasizing factors affecting the water balance in these summer-dry landscapes. The model simulates the soil moisture regime in terms of the interaction of water supply and demand: supply depends on precipitation and water storage, while evapotranspirational demand varies with solar radiation and temperature. The forest cover itself can affect the water balance via canopy interception and evapotranspiration. We simulated Sierran forests as slope facets, defined as gridded stands of homogeneous topographic exposure, and verified simulated gradient response against sample quadrats distributed across Sequoia National Park. We then performed a modified sensitivity analysis of abiotic factors governing the physical gradient. Importantly, the model's sensitivity to temperature, precipitation, and soil depth varies considerably over the physical template, particularly relative to elevation. The physical drivers of the water balance have characteristic spatial scales that differ by orders of magnitude. Across large spatial extents, temperature and precipitation as defined by elevation primarily govern the location of the mixed conifer zone. If the analysis is constrained to elevations within the mixed-conifer zone, local topography comes into play as it influences drainage. Soil depth varies considerably at all measured scales, and is especially dominant at fine (within-stand) scales. Physical site variables can influence soil moisture deficit either by affecting water supply or water demand; these effects have qualitatively different implications for forest response. These results have clear implications about purely inferential approaches to gradient analysis, and bear strongly on our ability to use correlative approaches in assessing the potential responses of montane forests to anthropogenic climatic change.     

Canberra''s Urban Forest: Evolution and planning for future landscapes

Canberra, Australia's national capital, is a planned city established on grazing lands in the southern tablelands of New South Wales. Over the past nine decades it has grown into a garden city of 300,000 people. Landscaping was an early priority as much of the chosen site for the city was a treeless plain. Major tree planting began in the 1920's and today the urban forest on public lands contains 400,000 trees from over 200 species in streets and parklands. The species used have changed over time with exotic deciduous trees and conifers dominating early plantings. By the 1970's native species, mostly eucalypts, were planted. Today fewer species comprising an equal mix of native and exotics are used. Trees in the earlier plantings are now mature and given the harshness of the local climate many will come to the end of their ‘safe life’ in the early decades of this century. This provides new challenges for urban tree managers as to how to effect tree replacement that is aesthetically pleasing, ecologically sound and socially acceptable. To assist in this planning a tree data base and modeling system has been assembled. This system – Decision Information System for Managing Urban Trees or DISMUT – facilitates the development of forest-level management programs by allowing the projection of change and work requirements that the result from historical and current plantings over the entire urban forest.     

Expanding the conservation toolbox: conservation planning of multifunctional landscapes

An area of convergence appears to be emerging between the approaches of conservation planning and the concepts of multifunctional landscapes, which if exploited correctly may assist in overcoming the resource and other constraints faced by biodiversity conservation, while at the same time furthering the aims of multifunctional landscapes to improve production abilities and overall sustainability. Using a multi-zone conservation planning approach, we explore the conservation costs, benefits to biodiversity conservation and possible ecosystem service payments associated with various land-use configurations, in the Little Karoo of South Africa, in order to develop and showcase a multifunctional landscape planning approach and its data requirements, as well as the possible cost savings to conservation agencies. The study uses four conservation planning scenarios, five land-use types, their conservation costs and biodiversity benefits, as well as possible payments from carbon sequestration and tourism. We find that the costs and biodiversity benefits associated with different land-uses varies substantially between land-uses, and also spatially within a land-use type. By incorporating this variation into a multi-zone conservation planning approach land-uses can be allocated in a way that achieves biodiversity targets while at the same time reducing costs by up to 50?% when compared with traditional binary approaches to conservation. Despite some challenges presented by cost and ecosystem service value data and the determination of land-use impacts on biodiversity and ecosystem services, the ability of conservation planning approaches to reflect differential contributions of particular land-uses to biodiversity targets and ecosystem services holds much potential for conservation planning, for multifunctional landscape objectives and for growing the resources and partnerships available to the establishment of sustainable and resilient landscapes.     

Linkages beyond borders: targeting spatial processes in fragmented urban landscapes

Management of ecosystems often focuses on specific species chosen for their habitat demand, public appeal, or levels of threat. We propose a complementary framework for choosing focal species, the mobile link concept, which allows managers to focus on spatial processes and deal with multi-scale ecological dynamics. Spatial processes are important for three reasons: maintenance, re-organization, and restoration of ecological values. We illustrate the framework with a case study of the Eurasian Jay, a mobile link species of importance for the oak forest regeneration in the Stockholm National Urban Park, Sweden, and its surroundings. The case study concludes with a conceptual model for how the framework can be applied in management. The model is based on a review of published data complemented with a seed predation experiment and mapping of Jay territories to reduce the risk of applying non-urban site-specific information in an urban setting. Our case study shows that the mobile link approach has several advantages: (1) Reducing the vulnerability of ecological functions to disturbances and fluctuations in resources allocated to management, (2) Reducing management costs by maintaining natural processes, and (3) Maintaining gene flow and genetic diversity at a landscape level. We argue that management that includes mobile link organisms is an important step towards the prevention of ecosystem degradation and biodiversity loss in increasingly fragmented landscapes. Identifying and managing mobile links is a way to align management with the ecologically relevant scales in any landscape.     

Karst landscapes of China: patterns,ecosystem processes and services

Landscape Ecology - The karst region of southwestern China, one of the largest continuous karsts in the world, is known for its unique landscapes and rich biodiversity. This region has suffered...     

Multifunctionality of floodplain landscapes: relating management options to ecosystem services

The concept of green infrastructure has been recently taken up by the European Commission for ensuring the provision of ecosystem services (ESS). It aims at the supply of multiple ESS in a given landscape, however, the effects of a full suite of management options on multiple ESS and landscape multifunctionality have rarely been assessed. In this paper we use European floodplain landscapes as example to develop an expert based qualitative conceptual model for the assessment of impacts of landscape scale interventions on multifunctionality. European floodplain landscapes are particularly useful for such approach as they originally provided a high variety and quantity of ESS that has declined due to the strong human impact these landscapes have experienced. We provide an overview of the effects of floodplain management options on landscape multifunctionality by assessing the effects of 38 floodplain management interventions on 21 relevant ESS, as well as on overall ESS supply. We found that restoration and rehabilitation consistently increased the multifunctionality of the landscape by enhancing supply of provisioning, regulation/maintenance, and cultural services. In contrast, conventional technical regulation measures and interventions related to extraction, infrastructure and intensive land use cause decrease in multifunctionality and negative effects for the supply of all three aspects of ESS. The overview of the effects of interventions shall provide guidance for decision makers at multiple governance levels. The presented conceptual model could be effectively applied for other landscapes that have potential for a supply of a high diversity of ESS.     

Revisiting futures: integrating culture,care and time in landscapes

Context

Two approaches to study landscape change have been exploited: one that tries to study the developments that have happened in the past, and another that tries to foresee future.

Objectives

We analyse how this dual approach can help understanding landscape change, how people relate to it in general, what their expectations and preferences are. We also discuss the usefulness of path dependency theory, cultural sustainability, and cultural ecosystem services approaches in understanding the management of a historical cultural landscape.

Methods

First, we revisit a 1999 scenario study that outlined the possible trajectories of change prior Estonian accession to the European Union in 2004. Then, through series of studies we track the wider context of the landscape changes, analysing the results from the interviews and combining those with the visible results. We seek to answer whether or not the landscape changes that occurred followed any of the past scenarios, and if people’s preferences changed.

Results

The dynamics of realisation of different scenarios was not straightforward. However, people showed clear preference towards landscapes that carried signs of the continuation of rural life. What was not foreseen when designing the scenarios was the upsurge of local identity creating the links with the past.

Conclusions

In this Estonian traditional cultural landscape, stewardship, culture and cultural ecosystem services, or nature’s contribution to people as IPBES prefers to call this now, define what caring for the landscape involves.

     

Dispersal success on fractal landscapes: a consequence of lacunarity thresholds

Habitat fragmentation is expected to disrupt dispersal, and thus we explored how patch metrics of landscape structure, such as percolation thresholds used to define landscape connectivity, corresponded with dispersal success on neutral landscapes. We simulated dispersal as either a purely random process (random direction and random step lengths) or as an area-limited random walk (random direction, but movement limited to an adjacent cell at each dispersal step) and quantified dispersal success for 1000 individuals on random and fractal landscape maps across a range of habitat abundance and fragmentation. Dispersal success increased with the number of cells a disperser could search (m), but poor dispersers (m<5) searching via area-limited dispersal on fractal landscapes were more successful at locating suitable habitat than random dispersers on either random or fractal landscapes. Dispersal success was enhanced on fractal landscapes relative to random ones because of the greater spatial contagion of habitat. Dispersal success decreased proportionate to habitat loss for poor dispersers (m=1) on random landscapes, but exhibited an abrupt threshold at low levels of habitat abundance (p<0.1) for area-limited dispersers (m<10) on fractal landscapes. Conventional metrics of patch structure, including percolation, did not exhibit threshold behavior in the region of the dispersal threshold. A lacunarity analysis of the gap structure of landscape patterns, however, revealed a strong threshold in the variability of gap sizes at low levels of habitat abundance (p<0.1) in fractal landscapes, the same region in which abrupt declines in dispersal success were observed. The interpatch distances or gaps across which dispersers must move in search of suitable habitat should influence dispersal success, and our results suggest that there is a critical gap-size structure to fractal landscapes that interferes with the ability of dispersers to locate suitable habitat when habitat is rare. We suggest that the gap structure of landscapes is a more important determinant of dispersal than patch structure, although both are ultimately required to predict the ecological consequences of habitat fragmentation.