Habitat Fragmentation Research Articles

DNA barcoding, visual-guide resource, new localities and host associations of genus Periglischrus Oudemans, 1902 (Acari: Mesostigmata, Spinturnicidae) from Minas Gerais, Brazil

The family Spinturnicidae (Oudemans, 1902) comprises hematophagous mites found exclusively on bats. In this article, we present DNA barcodes (mitochondrial Cytochrome c Oxidase I) for 71 specimens morphologically assigned to six spinturnicid species from 34 bat specimens (11 species) obtained from 10 caves and one forest fragment in karst areas from Minas Gerais state, southeast Brazil. A visual guide with diagnostic characters for Periglischrus acutisternus Machado-Allison, 1964, P. caligus Kolenati, 1857, P. herrerai Machado-Allison, 1965, P. iheringi Oudemans, 1902, P. paravargasi Herrin and Tipton, 1975, P. torrealbai Machado-Allison, 1965 is provided. Along DNA barcode data, photo-documentation of vouchering material of each individual sequenced have been deposited at BOLD (Barcoding of Life Data System v4) database. Periglischrus herrerai, P. caligus and P. paravargasi are reported for the first time in Minas Gerais state, extending their distribution ranges.

Effects of wave exposure and habitat fragmentation on growth and grazing of rocky shore seaweeds: a mesocosm experiment

Seaweeds are foundation species on rocky shores that are exposed to a series of stressors. These include wave exposure, desiccation, grazing, and human activities, with habitat fragmentation as a common result. As part of climate and biodiversity changes, we are expecting increased winds and more frequent storm events, warmer climate, and trophic downgrading of ecosystems, causing overgrazing events. Here, we present the results from a two-factorial mesocosm experiment on the relationship between wave exposure, habitat fragmentation and growth (branching and tip elongation) of Fucus vesiculosus in the intertidal and upper subtidal. We found that intertidal seaweeds branched significantly more at low than high wave exposure. There was no effect of habitat fragmentation on branching, and no effects on tip growth from either wave exposure or habitat fragmentation. The experiment suffered greatly from uncontrolled grazing. Gastropod coverage was higher inside seaweed patches than in the seaweed free areas between and outside of the patches. In basins with highly fragmented seaweed patches, we found more gastropods at low than high wave exposure, whereas in basins with low fragmentation we found more gastropods at higher wave exposure. The percent coverage of gastropods in the basins did not seem to impact seaweed growth.

Thermal habitat fragmentation in stratified lakes induces resource waves that brook charr track across seasons

The spatial configuration of thermal habitats constrains the thermoregulatory performance of ectotherms. Thermal landscapes also vary through time, which is particularly relevant in seasonal environments such as temperate lakes. Indeed, elevated temperatures in the epilimnion of dimictic lakes during summer could substantially reduce the use of this habitat by cold‐stenothermic fish during the stratified period. The main objective of this study was to evaluate whether thermal habitat fragmentation in stratified lakes modulates accessibility to resources that brook charr, Salvelinus fontinalis, which is a mobile consumer, can track across seasons. More specifically, we hypothesize that reduced access to the littoral habitat during summer enhances foraging opportunities in this habitat during winter. We used an automatic acoustic telemetry system offering full coverage of the lake to continuously record brook charr locations across seasons, and we estimated zoobenthos abundances in the littoral habitat using image processing and semi‐automatic classification. While brook charr concentrate in the metalimnion of the pelagic habitat in summer, most individuals in winter shift to a shallow bay that is unexploited in summer due to thermal constraints. In this habitat, zoobenthos abundance is more than twice as high at the end of the summer compared to littoral habitats close to the thermal refuge in the pelagic habitat. Surprisingly, brook charr showed strong within‐lake site fidelity between two consecutive summers, which suggests that spatial memory could be a key driver of seasonal habitat use in this lacustrine population. Overall, our results suggest that thermal barriers create fragmentation between littoral and pelagic habitats that in turn produces resource opportunities that brook charr can track across seasons.

Genetic Diversity, Mating System, and Seed Viability Reveal a Trade-Off between Outcrossing and Inbreeding in Pinus yunnanensis var. tenuifolia, an Ecologically Important Conifer Species Growing in a Hot-Dry River Basin Habitat in Southwest China

Revealing the relationship between the mating system (i.e., the outcrossing/inbreeding degree) and the fitness of seeds in tree species under wild conditions is essential for understanding the ecological adaptability and evolutionary stability of the species. This study collected open-pollinated seeds from seven wild populations of Pinus yunnanensis var. tenuifolia that exhibited fragmentation in the Nanpan–Hongshui River basin, an ecologically fragile area in China. The seeds and sprouts (germinated seeds) from 20 families were genotyped (24 seeds and 24 sprouts per family) using twelve microsatellite loci to reveal the genetic diversity, mating status, and effect of inbreeding on the three seed quality indicators (thousand-seed weight, germination rate, and germination potential). The three seed quality indicators differed significantly between families (p < 0.001). Higher values of genetic diversity (except the observed heterozygosity) were observed in the sprout group than those in the seed group. Families from different populations showed a notable genetic differentiation (Φst = 0.12), and a large part of families from the common populations had a high degree of coancestry, which signified that the current habitat fragmentation is limiting gene flow between populations. High levels of outcrossing rates (tm) were observed in both the seed group (tm = 0.974) and the sprout group (tm = 0.978), indicating that a low proportion of seeds were self-fertilized. Although there was a slightly higher single outcrossing rate (ts = 0.888) and a lower proportion of biparental inbreeding (tm − ts = 0.077) in sprouts compared to the seeds (ts = 0.871, tm − ts = 0.091), indicating that a part of inbred seeds were purged during the germination stage, curve fitting between the outcrossing rate and seed quality indicators showed that a certain degree of biparental inbreeding (ts between 0.89 and 0.91 and tm − ts between 0.09 and 0.11) did have a positive effect on seed germination ability. This highlights that excessive inbreeding or outbreeding seems to be unfavorable to seed viability. The peculiar relationship between seed viability and the mating system in P. yunnanensis var. tenuifolia was likely an evolutionary consequence of a trade-off between the nature of mixed mating and its specific ecological niche.

Quantifying the effects of landscape and habitat characteristics on structuring bird assemblages in urban habitat patches

Understanding the determinants of biodiversity in fragmented habitats is fundamental for informing sustainable landscape development, especially in urban landscapes that substantially fragment natural habitat. However, the relative roles of landscape and habitat characteristics, as emphasized by two competing frameworks (the island biogeography theory and the habitat diversity hypothesis), in structuring species assemblages in fragmented habitats have not been fully explored. This study investigated bird assemblages at 26 habitat patches (ranging in size from 0.3 to 290.4 ha) in an urban landscape, southwest China, among which habitat type composition and woody plant species composition varied significantly. Through 14 bird surveys conducted over six breeding seasons from 2017 to 2022, we recorded 70 breeding bird species (excluding birds recorded only once and fly-overs, such as raptors, swallows and swifts), with an average of 26 ± 10 (SD) species per patch. We found that patch area had significant direct and indirect effects on bird richness, with the indirect effects mediated by habitat richness (i.e., the number of habitat types). Isolation (measured as the distance to the nearest patch), perimeter to area ratio (PAR), and woody plant richness did not significantly predict variation in bird richness. Furthermore, none of these factors significantly sorted bird species based on their functional traits. However, the overall makeup of bird assemblages was significantly associated with the specific habitat types and woody plant species present in the patches. The results suggest that neither the island biogeography theory nor the habitat diversity hypothesis can fully explain the impacts of habitat fragmentation on bird richness in our study system, with their roles primarily being linked to patch area. The findings that habitat and plant compositions were the major drivers of variation in bird assemblage composition offer valuable insights into urban planning and green initiatives. Conservation efforts should focus not only on preserving large areas, but also on preventing urban monocultures by promoting diverse habitats within those areas, contributing to the persistence of meta-communities.

52,000 years of woolly rhinoceros population dynamics reveal extinction mechanisms

The extinction of the woolly rhinoceros (Coelodonta antiquitatis) at the onset of the Holocene remains an enigma, with conflicting evidence regarding its cause and spatiotemporal dynamics. This partly reflects challenges in determining demographic responses of late Quaternary megafauna to climatic and anthropogenic causal drivers with available genetic and paleontological techniques. Here, we show that elucidating mechanisms of ancient extinctions can benefit from a detailed understanding of fine-scale metapopulation dynamics, operating over many millennia. Using an abundant fossil record, ancient DNA, and high-resolution simulation models, we untangle the ecological mechanisms and causal drivers that are likely to have been integral in the decline and later extinction of the woolly rhinoceros. Our 52,000-y reconstruction of distribution-wide metapopulation dynamics supports a pathway to extinction that began long before the Holocene, when the combination of cooling temperatures and low but sustained hunting by humans trapped woolly rhinoceroses in suboptimal habitats along the southern edge of their range. Modeling indicates that this ecological trap intensified after the end of the last ice age, preventing colonization of newly formed suitable habitats, weakening stabilizing metapopulation processes, triggering the extinction of the woolly rhinoceros in the early Holocene. Our findings suggest that fragmentation and resultant metapopulation dynamics should be explicitly considered in explanations of late Quaternary megafauna extinctions, sending a clarion call to the fragility of the remaining large-bodied grazers restricted to disjunct fragments of poor-quality habitat due to anthropogenic environmental change.

The complete mitochondrial genome of Potomida acarnanica (Kobelt, 1879)

Freshwater mussels (Bivalvia, Unionida) play essential roles in the well-functioning of ecosystems, even providing essential services to humans. However, these bivalves face numerous threats (e.g. habitat loss and fragmentation, pollution, introduction of invasive species, and climate change) which have already led to the extinction of many populations. This underscores the need to fully characterize the biology of these species, particularly those, such as Potomida acarnanica, that are still poorly studied. This study presents the first mitogenome of P. acarnanica (Kobelt, 1879), an endemic species of Greece with a distribution limited to only two river basins. The mitochondrial genome of a P. acarnanica specimen, collected at Pamisos River (Peloponnese, Greece), was sequenced by Illumina high-throughput sequencing. This mitogenome (16,101 bp) is characterized by 13 protein-coding genes, 22 transfer RNA and 2 ribosomal RNA genes. The size of this mitogenome is within the range of another Potomida mitogenome already published for the species Potomida littoralis. In the phylogenetic inference, P. acarnanica was recovered as monophyletic with P. littoralis mitogenome in the Lamprotulini tribe, as expected. This genomic resource will assist in genetically characterizing the species, potentially benefiting future evolutionary studies and conservation efforts.

Individual variation in habitat selection behavior of Asian elephants in a human-wildland interface

Habitat loss and fragmentation due to accelerated agriculture expansion is a major threat to existing wildlife populations across Asia. The human-wildlife interface mosaic across Asia is varied in terms of juxtaposition and structure, which can strongly influence biodiversity value and impacts on wildlife species. Here we analyzed habitat selection behavior of Asian elephant (Elephas maximus) across three study sites with different agriculture use patterns in Myanmar, a country recognized as a global biodiversity hotspot, including but not limited to, commercial palm oil and sugarcane plantations, and subsistence agriculture. These different agriculture use landscape capture landscape mosaic structure found across Asia. Given elephants exhibit heterogeneous spatial behavior, we fitted individual step selection and resource selection models to gain insight into the diversity of strategies employed at the local (step) and home range (third-order) scale. We used variance partitioning analysis to quantify the explanatory contribution of individual and study sites across both scales. We found that the variation in the resource selection behavior was mainly due to individual differences, and the configuration of agriculture present in an individual’s range was the most influential to its selection behavior. Enhancing understanding of how the level of fragmentation on the landscape relates to agricultural use can serve to help focus conservation efforts. Continued accelerated agriculture expansion is increasing the rate of contact between elephants and humans and, thereby escalating negative human-elephant interactions, often resulting in human and elephant deaths. Gaining a deeper understanding of habitat selection behavior by elephants across the changing landscapes of Asia can help inform management decisions and conservation actions.

Presence of micronuclei and nuclear abnormalities in Caracara (Polyborus) plancus living in an airport area in southern Brazil

ABSTRACT The aviation sector is believed to be responsible for considerable environmental damage attributed to emission of a large number and amount of pollutants. Airports are often surrounded by forest fragments and humid areas that attract birds of prey and hence may potentially serve as useful bioindicators. The aim of the present study was to examine genotoxic potential in raptors exposed to airport pollution using the micronucleus (MN) test and morphological changes as evidenced by bilateral symmetry. This investigation was conducted at Salgado Filho International Airport of Porto Alegre – RS as well as in private and zoological breeding grounds. The presence of metals was measured in the blood cells of the collected birds. Seventeen birds (Caracara (Polyborus) plancus) were used in this study 11 from exposed and 6 from non-exposed group. The nuclear alterations clearly indicate that organisms exposed to airport pollution exhibited a significantly higher frequency of genetic damage compared to non-exposed birds. Further, manganese and chromium were detected exclusively in the blood of the exposed group. In contrast, the analysis of bilateral symmetry did not detect any significant morphologic differences between the two groups. Therefore, data indicate that blood genotoxic stress occurs in birds of prey living in civil aviation areas as evidenced by MN frequency increase and presence of manganese and chromium.

Three-lattice metapopulation model: Connecting corridor between patches may be harmful due to “hub effect”

Many authors have reported the risk of habitat fragmentation and the importance of connecting corridors between subpopulations (patches). However, we report that the connection of corridors may be harmful to species conservation. The paper deals with the birth and death processes of a single species living in a network composed of three patches. The disturbance due to a changing environment is assumed to affect only one patch. Two types of metapopulation models are applied. One is the lattice simulation model where we set a lattice as a patch. The other is based on metapopulation theory, which utilizes reaction-migration equations. The lattice simulation reveals that the connecting corridor between patches may be disadvantageous; the complete graph or a network with fully connected corridors is found not to be optimal for species conservation. Similar results are indicated by the application of metapopulation theory. We discuss the relationship between the risk of corridor construction and the effect of the hub patch.

Impacts of Habitat Fragmentation on Terrestrial Biodiversity in Tropical Forests in Democratic Republic of Congo

Purpose: The aim of the study was to examine impacts of habitat fragmentation on terrestrial biodiversity in tropical forests in Democratic Republic of Congo Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: The study found that habitat fragmentation poses a significant threat to terrestrial biodiversity in tropical forests, particularly in the Democratic Republic of Congo (DRC). The fragmentation of forest habitats due to human activities such as logging, agriculture, and infrastructure development leads to the isolation of species populations, loss of genetic diversity, and disruption of ecological processes. As a result, endemic species in the DRC, including primates, birds, and large mammals, face heightened risks of population decline and extinction. Moreover, habitat fragmentation exacerbates other environmental challenges, such as climate change and invasive species encroachment, further compromising biodiversity conservation efforts in the region. Unique Contribution to Theory, Practice and Policy: Metapopulation Theory, Landscape Ecology Theory & Island Biogeography Theory may be used to anchor future studies on impacts of habitat fragmentation on terrestrial biodiversity in tropical forests in Democratic Republic of Congo. Implement habitat corridors that physically link fragmented habitats, facilitating the movement of species and genetic exchange. These corridors should be strategically placed based on ecological modeling to maximize effectiveness. Develop and enforce integrated land-use policies that consider both conservation and development needs. Policies should promote land-use planning that minimizes habitat fragmentation and incorporates ecological networks.

Spatiotemporal analysis of land cover change, projection, and fragmentation: an application of Google earth engine and machine learning approach on Baraitali forest, Bangladesh

ABSTRACT Understanding the spatiotemporal dynamics of land cover/use change and forest fragmentation from 1981 to 2021 across the Baraitali Forest was very crucial for modeling future land cover, formulation of sustainable and robust forest/land-management strategies, and policy. The study adopted a mixed modern tool of Google Earth Engine platform, Machine Learning Algorithms, ArcGIS software, Land Change Modeller of TerrSet software, and FRAGSTATS programs. The study revealed that total land cover from 1981 to 2021 found a negative change in vegetative coverage, and a positive change in settlement which was more visible within the 6 land cover classes. Projections of future land cover for the next 10 years anticipate that vegetation coverage will be reduced by 65.96 ha, while settlement will be enhanced by 41.91 ha in 2031. The study also found conversions/transition of land cover throughout the research area. Overall change of spatiotemporal patterns was leading to substantial forest fragmentation. The overall accuracy and Kappa statistics for all the supervised land cover classifications were satisfactory. The study will fill an information gap by providing the revealed information at national and regional scales and may contribute to understanding of global change.

Construction of coastal zone ecological network based on the perspective of land-sea integration: A case study of Jinzhou City, China

The rapid urbanization of coastal zones has intensified ecological challenges in both land and marine environments, leading to increased landscape fragmentation. The scientific establishment of ecological network, which plays a pivotal role in safeguarding coastal biodiversity and ecological security, represents a significant approach to effectively connecting fragmented habitats within the coastal zone. The study selected Jinzhou in Liaoning Province and its adjacent coastal seas as the research area. The ecological sources within the study area were identified by supplementing ecological red line data, employing morphological spatial pattern analysis (MSPA), comprehensive habitat quality evaluation, landscape connectivity assessment, and ecological sensitivity evaluation. The land-sea integrated resistance surface was constructed by considering both natural and anthropogenic impacts. Ecological corridors were extracted based on circuit theory, and measures to optimize the ecological network were proposed. The results showed that: (1) The ecological sources of Jinzhou City was primarily distributed in the significant ecological functional areas or sensitive regions such as Yixian Yanwulu Mountain, Xihe Mountain, Dabijiashan special protection island, and Liaohe Estuary Protection area, with a total area of 1840.35 km2 (2) The ecological corridors within the study area were primarily located in the municipal areas of Jinzhou City District, Linghai City, Yixian County, Beizhen City, and Heishan County. The distribution of corridors in the sea area was relatively sparse. (3) The addition of supplementary ecological sources significantly improved the connectivity of the optimized ecological network. The results of the study can provide scientific insights for guiding the construction of coastal ecological networks and integrated land-sea ecosystem management in coastal regions.

Land-use change and habitat fragmentation of Leopardus pardalis in Highlands of Puebla, Mexico

Land-use change and habitat fragmentation of Leopardus pardalis in Highlands of Puebla, Mexico

Eugenia (Myrtaceae) from Reserva Natural Vale, Espírito Santo, a center of plant endemism in the Brazilian Atlantic Rainforest

Eugenia includes ca. 1,100 species worldwide and is the richest angiosperm genus of Brazilian flora with a remarkable biodiversity in the Atlantic Rainforest. In Espírito Santo state, the central-north region conserves the biggest forest fragment and is composed by the lowland coastal forests known as Tabuleiro. Considering the scarcity of studies approaching this vegetation and the high diversity of Eugenia species, this work presents a taxonomic treatment of Eugenia species from Reserva Natural Vale. The study area is located at the municipalities of Linhares and Sooretama, in the northern part of the coastal mesoregion of the state. For the taxonomic treatment, fieldwork was carried out between August 2015 and March 2019 and herbarium collections of BHCB, CVRD, CEPEC, ESA, HRCB, HPL, HUFSJ, ICN, K, MBM, MBML, RB, RBR, SORO, SP, SPF, SPSF, UB, UEC, and VIES were consulted, as well as images of nomenclatural types available online. This work points out the occurrence of 48 species of Eugenia within Reserva Natural Vale, encompassing 48% of the Eugenia species recorded in the Espírito Santo state. Six of them are presented as new occurrences for the reserve (Eugenia arenaria, E. disperma, E. florida, E. handroi, E. pachnantha and E. schottiana); two (E. pachnantha and E. schottiana) are first recorded for the state; E. adenophylla and E. infuscata are described as new. Eugenia adenophylla, E. atlantica, Eugenia cataphyllea, E. flavicarpa, E. hispidiflora, E. ochracea, E. penduliflora, and E. soteriana are endemic to Tabuleiro coastal forest, and E. handroi is the only record for Espírito Santo state. The most useful characters to distinguish the species are hair colours, especially in the floral structures, midvein on the adaxial surface of leaf blades, inflorescence type, connation and persistence of bracteoles, and the presence or absence of indumentum on the flowers’ hypanthia. Furthermore, morphological descriptions, distribution and phenology data, taxonomic comments, species illustrations, and an identification key for the species in the reserve are presented.

Long-Term Trends in Mosquito Vector Populations and Their Impact on Yellow Fever Outbreaks in Atlantic Forest Fragments of Rio De Janeiro, Brazil (2016-2021).

Among all living beings, mosquitoes account for the highest number of human fatalities. Our study aimed to determine mosquito egg abundance fluctuation from 2015 to 2020, in order to observe which years had the highest mosquito vector densities and whether they coincided with yellow fever virus outbreaks in both human and nonhuman primates. The study area included Atlantic Forest fragments in the state of Rio de Janeiro. Studies from the Diptera Laboratory at FIOCRUZ were selected and compared along a timeline period of the field collections. The highest peak in egg abundance from the analyzed studies was observed from 2016 to 2017 and from 2015 to 2016. The lowest egg abundance was during the collection periods from 2018 to 2019 and 2019 to 2020. The species with the highest abundance throughout all the periods of the studies analyzed was Haemagogus leucocelaenus, representing 87% of all epidemiological species identified. The species with the lowest abundance was Hg. Janthinomys, representing only 1%. Monitoring the population of mosquitoes is imperative for disease surveillance, as the rise in specimens of various vector species directly impacts the occurrence of yellow fever cases in both nonhuman primates and human populations.

A systematic literature review investigating the association between biodiversity and beaver lodges

Abstract The positive relationship between biodiversity and beaver‐modified habitats such as ponds, dams, and canals has been demonstrated; however, the association between biodiversity and beaver lodges is rarely investigated. Due to increasing habitat fragmentation, there is a growing need to identify local biodiversity hotspots. This systematic review assessed current scientific knowledge concerning the association between beaver lodges and biodiversity. Specifically, the study aimed to 1) investigate the evidence for beaver lodges being local biodiversity hotspots; 2) identify areas of future research centred around the relationship between biodiversity and beaver lodges; and 3) provide recommendations on how to monitor the relationship between biodiversity and beaver lodges within the UK. Through a stepwise process of database searching and literature sorting, a final dataset of 35 articles emerged, with each article including at least one species, besides beavers, interacting with beaver lodges. Analysis of the final dataset of articles showed beaver lodges offer multiple uses and fitness benefits for several species in highly seasonal environments, with daily and seasonal visitor variation influenced by intraspecific and interspecific interactions. Beaver lodges were shown to have higher species richness and diversity compared to microhabitats in the surrounding areas, supporting the concept of beaver lodges being local biodiversity hotspots. We recommend that future studies use videographic methodology to monitor beaver lodges and other treatment groups in the surrounding area. Using the described methodology, beaver management plans should monitor beaver lodges across the northern hemisphere, helping to further understand these important local biodiversity hotspots.

Fragmentation, birds, and conservation of the "Polylepis" Forest in Southern Peru

In the southernmost Andean regions of Peru, Moquegua, and Tacna, close to Chile and Bolivia borders, large forest stands of Polylepis species are essential for the social, economic, and environmental functionality of six basins. However, the need for more knowledge about their ecology, limited conservation efforts, and insufficient technical capacities for territorial regulation could accelerate their structural and functioning deterioration. Using landscape ecology -interdisciplinary science shaped by geography and biology- we found that in four evaluated areas, the composition of birds (and therefore also the resources they use) is differentiated by the influence of landscape fragmentation. Only two protected areas were legally recognized in the region, but they were established to cover small and remote isolated territories, which makes it challenging to conserve them effectively. Due to the poverty conditions common among the local communities, extractive or pastoralist activities conducted in large areas can trigger higher forest fragmentation rates. Under these circumstances, the valuable ecosystem services in the study area would be permanently lost or maintained at high risk. Because of these risks, specific measures were proposed to improve the social-environmental management of the forest by implementing mechanisms aimed at generating sustainable economic benefits in a healthy environment and social peace.

Time-lag effects of habitat loss, but not fragmentation, on deadwood-dwelling lichens

ContextLandscape habitat amount is known to increase biodiversity, while the effects of habitat fragmentation are still debated. It has been suggested that negative fragmentation effects may occur with a time lag, which could explain inconsistent results. However, there is so far no empirical support for this idea.ObjectivesWe evaluated whether habitat amount and fragmentation at the landscape scale affect the species density of deadwood-dwelling lichens, and whether these effects occur with a time lag.MethodsWe surveyed deadwood-dwelling lichens in woodland key habitats in two regions in northern Sweden, and modelled their species density as a function of past (1960s) and present (2010s) habitat amount (old forest area) and fragmentation (edge density) in the surrounding landscapes.ResultsPresent habitat amount generally had weak positive effects on lichen species density. Positive effects of the past habitat amount were stronger, indicating a time lag in habitat amount effects. Habitat fragmentation effects were generally weak and similar whether fragmentation was measured in the past or the present landscapes, indicating no time lag in fragmentation effects.ConclusionsWe found a time lag effect of habitat amount, but not fragmentation. This result is not consistent with suggestions that time lags explain the mixed observations of fragmentation effects. Time-lag effects of habitat amount suggest that the studied lichen communities face an extinction debt. Conservation should therefore prioritize increasing the amount of old forest, for example by creating forest reserves, to maintain the current lichen diversity. More generally, our results imply that studies examining only the present habitat amount risk under-estimating its importance.

Habitat Fragmentation Enhances the Difference between Natural and Artificial Reefs in an Urban Marine Coastal Tract

Coastal urbanization and the consequent proliferation of artificial structures greatly impact rocky reef communities, productive and diverse marine environments that play a crucial role in the functioning of broader coastal ecosystems. This study, conducted along a 7 km stretch of coastline at increasing distance from the port of Genoa (Ligurian Sea), investigated whether the alternating presence of artificial and natural reefs leads to discernible differences in the biota inhabiting these two reef types. The study area is one of the most anthropized areas of the Mediterranean Sea, exhibiting nearly 60% coastal artificialization, which severely impacts coastal ecosystems, favouring the replacement of sensitive species with more tolerant species. Ten reefs (5 natural and 5 artificial) were surveyed by scuba diving at about a 6-m depth, employing quadrats of 50 cm × 50 cm to estimate visually the percent cover of conspicuous sessile organisms. The artificial reefs hosted a similar number of species (18) to their natural counterparts (19) but exhibited a distinct community composition: the former were especially characterized by Jania rubens and filamentous algae, with the latter characterized by Peyssonnelia squamaria and Mesophyllum lichenoides. This difference, however, became negligible where coastal habitat fragmentation (here measured with a purposely devised Fragmentation Index) was minimal. Reducing fragmentation may therefore represent a management strategy to minimize the potential impact of artificial structures on marine biodiversity.