Spatial pattern of habitat quality modulates population persistence in fragmented landscapes

Habitat quality is one of the important factors determining population dynamics and persistence, yet few studies have examined the effects of spatial heterogeneity in within-patch habitat quality. In this paper, we use a spatially explicit agent-based model to investigate how habitat fragmentation and spatial pattern of within-patch habitat quality affect population dynamics and long-term persistence. We simulate three levels of habitat fragmentation (ranges from continuous to highly fragmented) and three types of spatial patterns in habitat quality within patches (i.e., negatively autocorrelated, randomly distributed, and positively autocorrelated). Hypothetical species differ in their niche specialization. The results demonstrate explicitly that the spatial pattern of within-patch habitat quality plays an important role in modulating the effects of habitat fragmentation on populations. Populations become less variable in size, and experience lower probability of extinction in landscapes with positively autocorrelated within-patch habitat quality. Specifically, specialized species are more vulnerable to habitat fragmentation, but this vulnerability is greatly mitigated by positively autocorrelated habitat quality within patches, in other words, exhibiting higher resistance to habitat fragmentation. The findings of this study suggest that managing habitat quality in existing habitat remnants is important to preserve species in habitats undergoing fragmentation, particularly for those with specialized habitat requirements.     

Contrasting effects of habitat quantity and quality on moth communities in fragmented landscapes

Habitat loss is commonly identified as a major threat to the loss of global biodiversity. In this study, we expand on our previous work by addressing the question of how lepidopteran species richness and composition vary among remnants of North American eastern deciduous forest located within agricultural or pastoral landscapes. Specifically, we tested the relative roles of habitat quantity (measured as stand area and percent forest in the greater landscape) and habitat quality (measured as tree species diversity) as determinants of moth species richness. We sampled >19 000 individuals comprising 493 moth species from 21 forest sites in two forested ecoregions. In the unglaciated Western Allegheny Plateau, the species richness of moths with woody host plants diminished as forest stand size and percent forest in the landscape decreased, but the total species richness and abundance of moths were unaffected by stand size, percent forest in the landscape, or tree species diversity. In contrast, the overall species richness and abundance of moths in the glaciated North Central Tillplain were affected primarily by tree species diversity and secondarily by forest size. Higher tree species diversity may reduce species loss from smaller forest stands, suggesting that small, diverse forests can support comparable numbers of species to those in less diverse, large stands. Smaller forests, however, contained a disproportionate number of moth species that possess larvae known to feed on herbaceous vegetation. Thus, although woody plant feeding moths are lost from forests with changes in stand area, new species appear capable of recolonizing smaller fragments from the surrounding habitat matrix. Our study further suggests that when species replacement occurs, local patch size and habitat quality may be more important than landscape context in determining the community structure of forest Lepidoptera.     

The quality and isolation of habitat patches both determine where butterflies persist in fragmented landscapes

Habitat quality and metapopulation effects are the main hypotheses that currently explain the disproportionate decline of insects in cultivated Holarctic landscapes. The former assumes a degradation in habitat quality for insects within surviving ecosystems, the latter that too few, small or isolated islands of ecosystem remain in landscapes for populations to persist. These hypotheses are often treated as alternatives, and this can lead to serious conflict in the interpretations of conservationists. We present the first empirical demonstration that habitat quality and site isolation are both important determinants of where populations persist in modern landscapes. We described the precise habitat requirements of Melitaea cinxia, Polyommatus bellargus and Thymelicus acteon, and quantified the variation in carrying capacity within each butterfly's niche. We then made detailed surveys to compare the distribution and density of every population of each species with the size, distance apart and quality of their specific habitats in all their potential habitat patches in three UK landscapes. In each case, within-site variation in habitat quality explained which patches supported a species' population two to three times better than site isolation. Site area and occupancy were not correlated in any species. Instead of representing alternative paradigms, habitat quality and spatial effects operate at different hierarchical levels within the same process: habitat quality is the missing third parameter in metapopulation dynamics, contributing more to species persistence, on the basis of these results, than site area or isolation. A reorientation in conservation priorities is recommended.     

Targeting habitat management in fragmented landscapes: a case study with forest vertebrates

Although improving the quality of habitat patches in fragmented landscapes is a main conservation target few studies have examined patch management in relation to the surrounding landscape. Tackling such an issue needs a cross-scale approach that takes the hierarchical nature of landscapes into account. Here I show the results of a cross-scale study focusing on the distribution patterns of ten forest vertebrate species (birds and mammals). The overarching goal of this study was to understand the strength of patch scale determinants of distribution, following the appropriate control for relevant landscape properties (e.g. habitat loss vs. habitat subdivision). I show how, after controlling for uncertainty in the detection of the species and for the role of landscape properties, patch scale variables still played an important role in determining occupancy patterns of forest vertebrates. For some species variation in the values of patch structure variables increased occurrence probability with only moderate levels of habitat loss, highlighting the fact that habitat management should be targeted towards precise landscape conditions. In other cases the effect of patch variables was strong therefore variation in their values always brought substantial increase/decrease of presence probability. Overall these results strongly suggest that habitat management should never be carried out irrespective of the properties of the surrounding landscape, rather, it should be carefully targeted towards specific landscape contexts (e.g. above a certain amount of habitat) where it is more likely to be effective.     

Linking habitat use to range expansion rates in fragmented landscapes: a metapopulation approach

Temperature increases because of climate change are expected to cause expansions at the high latitude margins of species distributions, but, in practice, fragmented landscapes act as barriers to colonization for most species. Understanding how species distributions will shift in response to climate change therefore requires techniques that incorporate the combined effects of climate and landscape‐scale habitat availability on colonization rates. We use a metapopulation model (Incidence Function Model, IFM) to test effects of fine‐scale habitat use on patterns and rates of range expansion by the butterfly Hesperia comma. At its northern range margin in Britain, this species has increased its breadth of microhabitat use because of climate warming, leading to increased colonization rates. We validated the IFM by reconstructing expansions in five habitat networks between 1982 and 2000, before using it to predict metapopulation dynamics over 100 yr, for three scenarios based on observed changes to habitat use. We define the scenarios as “cold‐world” (only hot, south‐facing 150–250° hillsides are deemed warm enough), “warm‐world” in which 100–300° hillsides can be populated, and “hot‐world”, where the background climate is warm enough to enable use of all aspects (as increasingly observed). In the simulations, increased habitat availability in the hot‐world scenario led to faster range expansion rates, and to long‐term differences in distribution size and pattern. Thus, fine‐scale changes in the distribution of suitable microclimates led to landscape‐scale changes in population size and colonization rate, resulting in coarse‐scale changes to the species distribution. Despite use of a wider range of habitats associated with climate change, H. comma is still expected to occupy a small fraction of available habitat in 100 yr. The research shows that metapopulation models represent a potential framework to identify barriers to range expansion, and to predict the effects of environmental change or conservation interventions on species distributions and persistence.     

Potential for industrial ecology to support healthcare sustainability: Scoping review of a fragmented literature and conceptual framework for future research

Healthcare is a critical service sector with a sizable environmental footprint from both direct activities and the indirect emissions of related products and infrastructure. As in all other sectors, the “inside‐out” environmental impacts of healthcare (e.g., from greenhouse gas emissions, smog‐forming emissions, and acidifying emissions) are harmful to public health. The environmental footprint of healthcare is subject to upward pressure from several factors, including the expansion of healthcare services in developing economies, global population growth, and aging demographics. These factors are compounded by the deployment of increasingly sophisticated medical procedures, equipment, and technologies that are energy‐ and resource‐intensive. From an “outside‐in” perspective, on the other hand, healthcare systems are increasingly susceptible to the effects of climate change, limited resource access, and other external influences. We conducted a comprehensive scoping review of the existing literature on environmental issues and other sustainability aspects in healthcare, based on a representative sample from over 1,700 articles published between 1987 and 2017. To guide our review of this fragmented literature, and to build a conceptual foundation for future research, we developed an industrial ecology framework for healthcare sustainability. Our framework conceptualizes the healthcare sector as comprising “foreground systems” of healthcare service delivery that are dependent on “background product systems.” By mapping the existing literature onto our framework, we highlight largely untapped opportunities for the industrial ecology community to use “top‐down” and “bottom‐up” approaches to build an evidence base for healthcare sustainability.     

Habitat quality of source patches and connectivity in fragmented landscapes

Because spatial connectivity is critical to dispersal success and persistence of species in highly fragmented landscapes, the way that we envision and measure connectivity is consequential for biodiversity conservation. Connectivity metrics used for predictive modeling of spatial turnover and patch occupancy for metapopulations, such as with Incidence Function Models (IFM), incorporate distances to and sizes of possible source populations. Here, our focus is on whether habitat quality of source patches also is considered in these connectivity metrics. We propose that effective areas (weighted by habitat quality) of source patches should be better surrogates for population size and dispersal potential compared to unadjusted patch areas. Our review of a representative sample of the literature revealed that only 12.5% of studies incorporated habitat quality of source patches into IFM-type connectivity metrics. Quality of source patches generally was not taken into account in studies even if habitat quality of focal patches was included in analyses. We provide an empirical example for a metapopulation of a rare wetland species, the round-tailed muskrat (Neofiber alleni), demonstrating that a connectivity metric based on effective areas of source patches better predicts patch colonization and occupancy than a metric that used simple patch areas. The ongoing integration of landscape ecology and metapopulation dynamics could be hastened by incorporating habitat quality of source patches into spatial connectivity metrics applied to species conservation in fragmented landscapes.     

The matrix matters: effective isolation in fragmented landscapes

Traditional approaches to the study of fragmented landscapes invoke an island-ocean model and assume that the nonhabitat matrix surrounding remnant patches is uniform. Patch isolation, a crucial parameter to the predictions of island biogeography and metapopulation theories, is measured by distance alone. To test whether the type of interpatch matrix can contribute significantly to patch isolation, I conducted a mark-recapture study on a butterfly community inhabiting meadows in a naturally patchy landscape. I used maximum likelihood to estimate the relative resistances of the two major matrix types (willow thicket and conifer forest) to butterfly movement between meadow patches. For four of the six butterfly taxa (subfamilies or tribes) studied, conifer was 3-12 times more resistant than willow. For the two remaining taxa (the most vagile and least vagile in the community), resistance estimates for willow and conifer were not significantly different, indicating that responses to matrix differ even among closely related species. These results suggest that the surrounding matrix can significantly influence the "effective isolation" of habitat patches, rendering them more or less isolated than simple distance or classic models would indicate. Modification of the matrix may provide opportunities for reducing patch isolation and thus the extinction risk of populations in fragmented landscapes.     

The importance of matrix quality in fragmented landscapes: Understanding ecosystem collapse through a combination of deterministic and stochastic forces

Increasing fragmentation of natural landscapes due to anthropogenic forces are changing the ecological structure of many systems. The corpus of literature has addressed the fact that there are many complex mechanisms that may lead to population and ecosystem collapse. Here, we propose an additional mechanism that combines the deterministic framework of complex oscillatory phenomena with the stochastic framework based on the spatial phenomena of island biogeography and metapopulation theory. Combining these two frameworks, which we believe exist in disturbed natural systems, we construct a situation in which collections of competitors are controlled by specialist natural enemies. Species are isolated in fragmented habitats separated by a matrix of decreasing ecological quality, which will determine immigration potential. In this system, species are exposed to stochastic extinction of spatial immigration potential and deterministic extinction of standard oscillatory frameworks. Through the combination of these extinction events, we see that many natural systems may become increasingly unstable and subject to unexpected consequences with changes to the matrix environment. The combined effect of these two extinctions pathways highlights the need to maintain high immigration rates in order to offset possible ecosystem collapse in fragmented systems. The results highlight the importance of landscape conservation efforts, especially towards maintaining matrix environments with greater ecological integrity.     

Patch occupancy by stone martens Martes foina in fragmented landscapes of central Spain: the role of fragment size,isolation and habitat structure

We studied the response to forest fragmentation of a generalist carnivore, the stone marten Martes foina, in highly fragmented landscapes of central Spain. Five different areas (n = 178 fragments) in central Spain were surveyed. This paper analyses the relationship between fragment use by martens (measured through scat presence) and a series of variables related to the size, isolation and vegetation structure of each fragment by means of stepwise logistic regression. Size and isolation have an important effect on stone marten presence in fragments. Our results were similar to those found for other marten species in landscapes with coarse-grain fragmentation, but they contrast with other studies conducted in landscapes with fine-grain fragmentation. These data suggested that in highly fragmented landscapes, size and isolation factors resulting from forest fragmentation were responsible for determining marten responses, irrespective of their habitat generalism. Management policies for the stone marten in highly fragmented scenarios require the maintenance of large forests near continuous forest tracts in mountains or riparian woodlands.     

Aspen lichens in agricultural and forest landscapes: the importance of habitat quality

The amount of aspen Populus tremula , has declined in the boreal forest landscape. This decline is especially marked in young and intermediate stands due to the lack of regeneration. Aspen regeneration is nowadays mainly restricted to abandoned agricultural land. The decrease of aspen is of particular concern as it has more host-specific species than any other boreal tree species. The main question addressed is whether regenerating aspen stands in agricultural habitats can compensate for the deficiency of young stands in the forest. Data on epiphytic macrolichens show that cyanolichens increased, in number and frequency, with stand age in the forest landscape, and that there was a striking difference in species composition between stands in the two landscapes. Lichens with cyanobacterial and green-algal photobionts dominated in the forest and agricultural stands, respectively. Notably, cyanolichens were not found in stands younger than 50 yr in the forest, and stands younger than 100 yr in the agricultural landscape. This difference between the landscapes cannot be explained by stand age, stand size or isolation. Instead, differences in habitat quality, due to differences in the physical environment associated with the presence of conifers in the older forest stands, appear to be involved. We suggest that in order to conserve cyanolichens that are confined to aspen, active management practices have to be adopted that promote the regeneration of aspen in the forest landscape, and the establishment of conifers in areas where aspen regeneration is confined to the agricultural landscape. In addition, until new aspen stands with appropriate physical environments have been established, these measures must be combined with the preservation of existing old-growth stands, which can provide appropriate source populations.     

Song parameters of the fuscous honeyeater Lichenostomus fuscus correlate with habitat characteristics in fragmented landscapes

Both avian abundance and species richness decline in response to habitat loss and fragmentation. Studying variation in bird song structure across modified landscapes can provide insights into the effects of habitat alterations on coherence of social interactions within populations. Here, we tested whether fragmentation or change of habitat quality within box‐ironbark forest of central Victoria impacted cultural connectivity and song characteristics in fuscous honeyeater, a declining common Australian bird. First, we tested whether geographic distance and/or spatially‐explicit landscape connectivity models can explain patterns of song similarity across fragmented landscapes. We found no evidence that distance or habitat fragmentation impacts the nature and transmission of fuscous honeyeater song, and concluded that acoustic connectivity at the scale of our study is high. Second, we tested whether variation in habitat quality explains variation in song characteristics. In accordance with acoustic adaptation to habitat structure, birds sang longer songs in sites with more large trees and produced longer common song elements in sites with greater tree height. However, the acoustic adaptation hypothesis cannot explain the finding that in less‐disturbed landscapes with higher tree‐cover birds sang songs (and song elements) with higher maximum frequency and wider frequency bandwidth. We also found that birds sing longer and more variable songs of wider frequency bandwidth in less disturbed sites with a greater number of large mature trees, which may represent better feeding resources. Our study suggests that changes in song structure with habitat degradation could signal disturbed population processess, such as changes in the acoustic communication among resident birds.     

Bees in the six: Determinants of bumblebee habitat quality in urban landscapes

With growing urbanization, it is becoming increasingly important to design cities in a manner that sustains and enhances biodiversity and ecosystem services. Native bees are critical pollinators that have experienced substantive declines over the past several decades. These declines have captured the attention of the public, particularly urbanites, prompting a large interest in protecting pollinators and their habitats in cities across North America and Europe. Unfortunately, we currently lack research about specific features of urban environments that can enhance the fitness of pollinators. We carried out an intensive study of Bombus impatiens, the Common Eastern Bumblebee, in the city of Toronto (Canada''s largest city), to better understand landscape parameters that provide high‐quality habitat for this species and likely other generalist bees. We divided the city into 270 grid cells and sampled a large number of worker bees, which were then genotyped at twelve hypervariable microsatellite loci. The genetic data allowed us to quantify the effective number of colonies and foraging distance for bumblebees in our study area. We then asked how the city''s landscape and human population demography and income are associated with the availability of high‐quality habitat for B. impatiens. Several aspects of Toronto''s landscape influenced colony density and foraging range. Urbanization had a clear effect on both colony density and foraging distance of workers. On the other hand, functional (i.e., not cosmetic) green space was often associated with higher quality habitats for bumblebees. Our study suggests several planning strategies to enhance habitat quality for bumblebees and other pollinators in cities.     

A decadal review of urban ornithology and a prospectus for the future

The study of urban birds has increased exponentially in the last century. A prior review of the scientific literature up to the year 2000 found 100 research articles on urban birds, but in the past decade alone, over 1000 have been published. Here I review the studies from 2006–2015 to characterize their approach, location, general findings and recent obsessions, with an eye toward suggesting important future directions. Urban ornithology remains centred in the northern hemisphere, although there is a rapid increase in studies from southern, tropical and biodiverse settings. Studies in the north have changed from documentation of the composition of urban avifaunas to include many studies of the demographic response to aspects of urban environments. Studies of pattern remain most common in Latin America, Asia, Africa, New Zealand and the Middle East. Across the world, ornithologists are revealing the rapid evolution of behavioural and morphological adaptations by birds to the urban environment, much of which is due to phenotypic plasticity. The relationship of humans to nature generally and birds specifically has been increasingly studied as a driver of avifaunal change as well as a factor affecting human ethics. Urban ornithology remains rarely experimental, but it has matured to the point of supporting synthetic reviews and meta‐analyses that quantify the loss of avian diversity from city centres, characterize successful urban birds, discuss the role of amount and arrangement of vegetation on bird life, and explore the complex relationships between the subsidies and hazards of urban life and the survival and reproduction of birds. Yet much remains to be learned, including how some species thrive in cities with abundant predators; how city form and location affect the peak in avian richness that occurs typically at intermediate levels of urbanization; the significance of functional biotic homogenization; and the ways in which engaging citizens in urban bird life informs their broader environmental land ethic.     

The role of small secondary biotopes in a highly fragmented landscape as habitat and connectivity providers for dragonflies (Insecta: Odonata)

Habitat loss and degradation are considered major threats to freshwater biodiversity and to invertebrates in particular. These often irreversible processes may lead to local and regional extinctions of species, most notably of stenotopic taxa. In spite of this, a number of studies have shown that small habitat patches can sustain rich and abundant communities. The present work assesses the relevance of a group of four small man-made (secondary) wildlife ponds to Odonata species diversity and abundance. Results obtained on pond recruiting capacity, species richness, abundance and habitat use by means of exuviae collection and monitoring of adults using a capture–mark–recapture (CMR) method indicate the potential suitability of these small aquatic biotopes and the surrounding landscape as habitat providers and stepping stone connectors in the Vallès lowlands (Catalonia, Spain). This region, close to the metropolitan area of Barcelona, has severely degraded natural habitats and high landscape fragmentation due to infrastructure, urban and industrial expansion. A comparison among a greater number of sites (ponds and sections of streams and rivers) distributed across the region showed that adequately managed small waterbodies harbour richer Odonata communities than others that are unmanaged or managed specifically for other types of fauna or uses. Appropriate care of these small biotopes avoids disturbance and keeps them free from vertebrates like fish and waterfowl which, under certain conditions, may have a strong influence on the invertebrate communities because, apart from feeding on larvae, they may have a negative impact on macrophyte development and water quality. While rivers and streams, the only natural aquatic habitats in the area, may be both expensive and technically challenging to restore and manage successfully, the creation and/or restoration of small ponds and short river sections in suitable locations can be a cost-effective method for enhancing freshwater vegetation and invertebrate diversity in this impacted landscape.     

破碎化次生林斑块面积及栖息地质量对繁殖鸟类群落结构的影响

于1998～2000年夏季。运用GPS定位系统确定了12块面积范围为6．5～112．8hm。的彼此隔离的森林斑块。比较了斑块面积和栖息地质量对繁殖鸟类群落结构的影响。结果表明：不同面积斑块中繁殖鸟类的群落结构有所差异。各斑块所容纳的繁殖鸟类的物种数从4种到26种不等。鸟类物种数随着斑块面积的增大而增多。不同鸟类对斑块面积的反应并不相同,耐边缘种偏爱面积较小的斑块。而非边缘种偏爱在大面积的斑块中繁殖。斑块栖息地质量也是影响鸟类群落结构的重要因素,质量好的斑块包容的鸟类物种较多。鸟类物种丰富度与斑块质量的相关性(R2=0．67)小于与斑块面积的相关性(R2=0．88)。各斑块中的鸟类群落结构在不同年份间比较相似。栖息地破碎化不但缩小了栖息地面积。同时也不同程度地降低了栖息地的质量。从而消极地影响着鸟类群落结构的稳定性和鸟类的物种多样性。     

The effects of habitat destruction in finite landscapes: a chain-binomial metapopulation model

We present a stochastic model for metapopulations in landscapes with a finite but arbitrary number of patches. The model, similar in form to the chain-binomial epidemic models, is an absorbing Markov chain that describes changes in the number of occupied patches as a sequence of binomial probabilities. It predicts the quasi-equilibrium distribution of occupied patches, the expected extinction time (τ¯), and the probability of persistence (l¯(x)) to time x as a function of the number N of patches in the landscape and the number S of those patches that are suitable for the population. For a given value of N , the model shows that: (1) τ¯ and l¯(x) are highly sensitive to changes in S and (2) there is a threshold value of S at which τ¯ declines abruptly from extremely large to very small values. We also describe a statistical method for estimating model parameters from time series data in order to evaluate metapopulation viability in real landscapes. An example is presented using published data on the Glanville fritillary butterfly, Meltiaea cinxia , and its specialist parasitoid Cotesia melitaearum . We calculate the expected extinction time of M. cinxia as a function of the frequency of parasite outbreaks, and are able to predict the minimum number of years between outbreaks required to ensure long-term persistence of M. cinxia . The chain-binomial model provides a simple but powerful method for assessing the effects of human and natural disturbances on extinction times and persistence probabilities in finite landscapes.     

Assessing habitat quality of farm-dwelling house sparrows in different agricultural landscapes

Having historically been abundant throughout Europe, the house sparrow (Passer domesticus) has in recent decades suffered severe population declines in many urban and rural areas. The decline in rural environments is believed to be caused by agricultural intensification, which has resulted in landscape simplification. We used giving-up densities (GUDs) of house sparrows feeding in artificial food patches placed in farmlands of southern Sweden to determine habitat quality during the breeding season at two different spatial scales: the landscape and the patch scale. At the landscape scale, GUDs were lower on farms in homogeneous landscapes dominated by crop production compared to more heterogeneous landscapes with mixed farming or animal husbandry. At the patch level, feeding patches with a higher predation risk (caused by fitting a wall to the patch to obstruct vigilance) had higher GUDs. In addition, GUDs were positively related to population size, which strongly implies that GUDs reflect habitat quality. However, the increase followed different patterns in homogeneous and heterogeneous landscapes, indicating differing population limiting mechanisms in these two environments. We found no effect of the interaction between patch type and landscape type, suggesting that predation risk was similar in both landscape types. Thus, our study suggests that simplified landscapes constitute a poorer feeding environment for house sparrows during breeding, that the population-regulating mechanisms in the landscapes differ, but that predation risk is the same across the landscape types.