Changes In Habitat Structure Research Articles

Out of shape: Ocean acidification simplifies coral reef architecture and reshuffles fish assemblages.

Climate change stressors are progressively simplifying biogenic habitats in the terrestrial and marine realms, and consequently altering the structure of associated species communities. Here, we used a volcanic CO2 seep in Papua New Guinea to test insitu if altered reef architecture due to ocean acidification reshuffles associated fish assemblages. We observed replacement of branching corals by massive corals at the seep, with simplified coral architectural complexity driving abundance declines between 60% and 86% for an assemblage of damselfishes associated with branching corals. An experimental test of habitat preference for a focal species indicated that acidification does not directly affect habitat selection behaviour, with changes in habitat structural complexity consequently appearing to be the stronger driver of assemblage reshuffling. Habitat health affected anti-predator behaviour, with P. moluccensis becoming less bold on dead branching corals relative to live branching corals, irrespective of ocean acidification. We conclude that coral reef fish assemblages are likely to be more sensitive to changes in habitat structure induced by increasing pCO2 than any direct effects on behaviour, indicating that changes in coral architecture and live cover may act as important mediators of reef fish community structures in a future ocean.

Comparing the Structure of Fish Assemblage among Natural and Artificial Shallow Rocky Habitats

Artificial coastal structures, such as seawalls, breakwaters, and groins, can exert various impacts on the fish communities in the nearby regions. This study focuses on assessing the ecological effects of coastal infrastructure on marine environments, by comparing, at different seasons, the habitat complexity and heterogeneity, as well as their effects on fish assemblages, between the artificial habitat created with the intention of constructing a marina (Puerto Amor) and the natural habitats surrounding the Cabo de la Huerta area in Alicante (Spain). Employing an asymmetric design and examining two temporal and spatial scales, we utilized visual censuses in snorkeling to gauge the abundance and size of fish species, alongside various parameters related to habitat complexity and heterogeneity. The overarching hypothesis is that fish populations associated with artificial habitats will differ in terms of abundance, biomass, species richness, and diversity compared to fish populations associated with natural habitats, due to changes in complexity and heterogeneity. The findings indicate a shift in fish assemblages; for example, the family Labridae showed differences between the two habitat types for several species. These changes were due to the influences of the Posidonia oceanica meadow and algae like Jania rubens; being influenced by biological variables such as Ellisolandia elongata, Oculina patagonica, and Sarcotragus spinosulus; as well as physical variables such as stones, gravel, and blocks. While there is evidence of alteration in fish assemblages due to changes in habitat structure, there is also an increase in richness (9 species/m2) and total abundance and biomass (1000 ind./m2 and 1700 g/m2, respectively) in the artificial habitat. Multivariate analyses reveal that the fish community in Puerto Amor is less homogeneous than the one in the natural habitat. However, these analyses also indicate an overlap between the communities of both habitats, suggesting substantial similarity despite the noted differences. Consequently, although the habitat alteration has impacted fish populations, it has not diminished abundance, biomass, or species richness. In conclusion, the artificial rocky habitat resulting from the construction attempt at Puerto Amor harbor has fish populations with ecological significance and its removal could lead to undesirable impacts in the area, as the fish assemblages have become well established.

Mice population dynamics and structure over time and space after wildfires

AbstractRodents respond quickly to changes in habitat structure after wildfires. They constitute important prey items for vertebrate predators and influence vegetation structure and regeneration. Assessing the population dynamics of rodents in burnt areas, whether individuals originate from in situ survival or from ex situ immigration, is therefore a key question in understanding the recovery of trophic networks after disturbance. This study aimed to identify the recovery strategies of rodent populations in recently burnt forests in the Mediterranean basin using body condition, reproductive output, sex ratios, and distance covered by wood mice and Algerian mice. Sampling stations were set up at increasing distances from the perimeter of recently burnt areas. Rodents were captured using Sherman traps and measured. Wood mice and Algerian mice lived syntopically within the recently burnt areas studied, the former species being more abundant and the second one selecting drier areas. Results indicated that time since fire, shrub cover, and distance to the perimeter of the burnt area influenced wood mice and Algerian mice population structures. Adult female wood mice mainly remained close to the burnt area perimeter, due to this species' matriarchal structure, while juvenile males dispersed farther into the burnt area. Adult females were also recaptured more frequently than other age and sex categories over time, whereas males covered greater distances. These findings suggest that the recovery strategy of these widespread Mediterranean rodents is mainly driven by ex situ immigration from unburnt areas. These results will be useful for post‐fire management decisions such as non‐intervention, salvage logging or the conservation of open areas, given that mice are a fundamental component of the ecosystem. Results also suggest that management should focus on maintaining good connectivity between burnt and adjacent unburnt areas to support mice populations and facilitate other longer‐term conservation benefits.

Impact of livestock grazing on the terrestrial arthropod diversity in the arid zone of Mongolia

Arthropods play an essential role in steppe ecosystems. However, studies testing the overall response of terrestrial arthropods to overgrazing are scarce. The problem is particularly worrisome in Central Asia, while, to date, only a very few broader studies have been conducted in this region. We investigated how epigeic terrestrial arthropod assemblages respond to different livestock grazing pressure in two ecozones in SE Mongolia by examining their structure using pitfall traps. We also assessed which groups can be utilised as the most efficient indicators of grazing intensity. Our analyses demonstrated that the habitat type, grazing intensity, and the interaction of these variables had a significant effect on the overall species composition and abundance. However, the grazing intensity caused different changes in the composition of arthropod communities in both studied ecozones. Contrary to the semi-desert, in the steppe habitat, the grazing had the strongest impact in the moderately grazed site. It is most likely because steppe-dwelling species are more sensitive to loss of plant biomass and changes in habitat structure. We also found that the most representative species within and from different groups can react differently to changing grazing intensities, indicating with their presence the characteristics of the respective habitat. Such differences should also be considered when elaborating the management plan of conserved species but also when applying grazing management in different habitat types. Our survey is one of the most comprehensive in Central Asia and should help implement further, more targeted studies in the corresponding habitats.

Impact of Microplastic Pollution on Freshwater Ecosystems and Effective Mitigation Measures in Canada

Purpose: This study investigates the impact of microplastic pollution on freshwater ecosystems and effective mitigation measures in Canada.
 Methodology: The study adopted a desktop methodology. Desk research refers to secondary data or that which can be collected without fieldwork. Desk research is basically involved in collecting data from existing resources hence it is often considered a low-cost technique as compared to field research, as the main cost is involved in executive’s time, telephone charges and directories. Thus, the study relied on already published studies, reports and statistics. This secondary data was easily accessed through the online journals and library.
 Findings: The literature review and research findings demonstrate that microplastic pollution is significantly impacting freshwater ecosystems in Canada. Microplastics can accumulate in water, biota, and sediments, leading to water quality changes, ecological disruptions, and potential risks to human health. The study also highlights the ecological and societal impacts of microplastic pollution, such as changes in habitat structure, alterations in food webs, and potential health risks. Various mitigation measures, including source reduction, wastewater treatment, education and awareness, policy and regulatory measures, and ecosystem-based approaches, are effective in reducing microplastic pollution in freshwater environments.
 Recommendations: This study contributes to the understanding of microplastic pollution's impact on freshwater ecosystems and effective mitigation measures in Canada. The research advances knowledge in environmental science, freshwater ecology, and pollution management, providing insights into sources, pathways, and impacts of microplastic pollution in freshwater ecosystems, and the effectiveness of various mitigation measures. The findings have practical implications for policymakers, environmental managers, and stakeholders involved in freshwater management and pollution control, highlighting the need for interdisciplinary approaches, stakeholder engagement, and evidence-based policy and management strategies to mitigate the negative effects of microplastic pollution on freshwater ecosystems and safeguard their health and sustainability.

Olive grove intensification negatively affects wintering bird communities in central Spain

Agricultural intensification is a persistent and growing threat to biodiversity worldwide. Olive groves cover extensive areas in the Mediterranean basin and play a fundamental role as refuge and wintering quarters for many bird species, but the effects of their current intensification on bird communities remain unclear. This study aims to evaluate the response of wintering birds to the management of olive groves with different degrees of intensification (traditional, intensive and super-intensive management) in central Spain. Based on two bird censuses conducted in 25 groves in early and late winter, we examined the influence of habitat structure and composition at different spatial scales on species richness and abundance of the entire farmland bird community, and of the diet-based functional groups. Total species richness tended to decrease with intensive olive grove management, probably due to reduced habitat heterogeneity, whereas total abundance did not, indicating the capacity of intensive and super-intensive olive groves to sustain large numbers of wintering birds. The negative effect of intensification was particularly evident in frugivore species richness, while frugivore abundance was positively (but marginally) associated with olive fruit availability. Granivorous species were positively associated with lower vegetation cover, but insectivorous species did not respond to intensification gradients. Species richness and abundance (total and by diet-based functional groups) also decreased from early to late winter, which may be due to the effect of olive harvest, but also to an extreme cold event. Overall, our findings show how olive grove intensification and the associated management practices result in significant changes in habitat structure and composition at different spatial scales, thus affecting wintering bird communities.

Forest conversion into pasture selects dung beetle traits at different biological scales depending on species pool composition.

The conversion of forests into open areas has large effects on the diversity and structure of native communities. The intensity of these effects may vary between regions, depending on the existence of native species adapted to open habitats in the regional pool or the time since habitat change.We assess the differences in species richness and functional diversity of dung beetle communities (Coleoptera: Scarabaeinae) between native forests and novel pasturelands of the Atlantic Forest and the Cerrado, two biomes with contrasting histories of human occupation in Brazil. We conducted standardized surveys in seven forest fragments and adjacent pastures in each region and measured 14 traits in individuals collected in each type of habitat at each particular site. We calculated functional richness, functional evenness, functional divergence, and community-weighted mean of traits for each area, and analyzed individual variation through nested variance decomposition and Trait Statistics.Communities were richer and more numerous at the Cerrado. We did not find any consistent relationship between functional diversity and forest conversion beyond the changes in species diversity. Although landscape changes were more recent at the Cerrado, the colonization of the new habitat by native species already adapted to open habitats lessens the functional loss in this biome. This indicates that habitat change's effects on trait diversity depend on the regional species pool rather than on time since land conversion.Forest conversion effects were primarily due to internal filtering. The effects of external filtering only appear at the intraspecific variance level, with contrasting differences between the Cerrado, where traits related to relocation behavior and size are selected, and the Atlantic Forest, where selection operates for traits related to relocation behavior and flight. These results evidence the importance of considering individual variance to address the responses of dung beetle communities to forest conversion.

Effects of Post-Fire Management on a Mediterranean Small Mammal Community

Wildfires simplify ecosystems, modifying the ecological niches of the fauna living in the recently burned areas. Small mammals respond rapidly to changes in habitat structure and composition after fire, but the effects of fire can be ameliorated by some management strategies (e.g., salvage logging). Hence, it is necessary to explore whether alternative management strategies may be able to return the ecosystem to its initial state. We studied the small mammal community by live trapping on eight plots under different post-fire treatments in Sant Llorenç del Munt i l’Obac Natural Park (Barcelona province, NE Spain). At the community level, an increase in overall relative abundance and species density was observed in the burned areas. Apodemus sylvaticus, the most abundant mammal in study area, used woody debris piles as a shelter against predators. Mus spretus was more abundant in post-fire sites with large open areas interspersed with woody debris piles. Crocidura russula steadily increased its presence in later successional stages when ground cover became more complex. Our results suggest that combining different management strategies may be appropriate to improve the habitat suitability and biodiversity of small mammals and other key open-land species throughout the burned area.

Population Density and Stability of Breeding Birds in English Oak Woodland Over a 32-Year Period in Relation to Habitat Structure and Edges

Long-term breeding bird censuses in Białowieża National Park (BNP), north-east Poland, have revealed rather low densities of birds and high community stability which may be features of near-natural forest conditions. This paper reports on a long-term census of breeding birds in 50 ha of oak woodland in central England which contained both managed and undisturbed areas. New information is provided on breeding bird density and its spatial variation within English mature broadleaved woodland to address two questions: Under what circumstances are English woods likely to support higher densities than those occurring in BNP? Is there evidence that population and community stability is lower in English woodland? The overall bird density was lower than in the BNP oak-hornbeam stands, at the scale of both the whole study area and the undisturbed stands. Densities of three of the five dominant species (Cyanistes caeruleus, Parus major, Troglodytes troglodytes) were lower in BNP, Fringilla coelebs was higher, while Erithacus rubecula was similar. Within the undisturbed stands, densities of seven of 12 species, including T. troglodytes, were similar to those in BNP, two were considerably higher (C. caeruleus, P. major) and one much lower (F. coelebs). Selection of the external woodland edge by several species resulted in relatively high overall densities in the edge zone. The broad composition of the bird community remained fairly stable with the exception of declines in tropical migrants and increases in shrub layer nesters. Temporal abundance patterns of species showed much individuality. Trends of several species appeared to be driven by changes in habitat structure. However, the same species remained numerically dominant or characteristic of the wood throughout the study period. This suggests there was a core of resilient species, much as proposed for BNP. Although caution is needed in drawing conclusions from a single site, with the exception of a small number of species, in recent decades there is unlikely to have been a general pattern of higher densities of birds in English woodland than in BNP. However, some English woods with highly complex vegetation structures, or a high proportion of edge habitat, do have exceptionally high densities (> 100 territories/10 ha).

The relationship between moose browsing, habitat structure and predation pressure on insect herbivores

Grazing and browsing by large ungulates can have a strong effect on habitat composition and structure. Associated effects can be reduction in the abundance of palatable tree species and alter understory properties, thereby affecting habitat complexity. Changes in habitat structure and complexity can in turn affect arthropod predation pressure, as arthropod predators are strongly influenced by habitat characteristics. This may be increasingly important in production forests, as such systems are often more vulnerable to disturbances such as pest insects. However, studies exploring this indirect link between ungulates and predation rate are sparse. We explore this link through the comparison of fenced plots excluding ungulates (for four years) with associated control plots replicated in 16 forest stands covering a large geographical area. We measured vegetation characteristics to assess the effect of exclusion on habitat structure. We used plasticine models to compare predation rates in fenced and control plots on pine trees. In addition, we sampled herbivorous insects to explore the potential relationship between predation and herbivore abundance. We could only demonstrate a weak effect of browser exclusion on habitat structure, suggesting that the time of exclusion was too short to cause a vegetation response. In terms of arthropod predation, we found that predation was positively affected by understory cover, but not related to herbivore abundance. Understory properties such as species composition and biomass has been demonstrated to be affected by ungulates in other studies. Therefore, we propose that ungulate browsing – despite weak effects of browsing exclusion in our study – can affect arthropod predation via changes in the understory, which could potentially affect pest populations. Our study is one of the first attempts to connect effects of mammalian browsing to changes in predation rates on herbivorous insects.

Influence of roads on space use by European hares in different landscapes

ContextRoads are ubiquitous in human inhabited landscapes, and can impact animal movement and population dynamics, due to barrier effects, road mortality, but also by providing resources at road verges. Thus, we need a better understanding of how roads, in interaction with seasonal changes in habitat structure, affect space use and habitat selection of the animals that persist in these landscapes.ObjectivesHere, we used the European hare (Lepus europaeus) as model species to investigate how human-induced changes in landscape composition—measured as road density, land cover type, and field size—affect home range location, seasonal habitat selection and road crossings, which are likely to correlate with wildlife-vehicle collision risk.MethodsWe collected > 240,000 GPS positions of 90 hares from three populations (one in Denmark and two in Germany) that differed regarding agricultural intensification and road density. Using this data, we analyzed home range location and habitat selection (using step-selection functions) in relation to roads, habitat composition, and seasonality, and quantified how these factors affected road crossings by hares.ResultsIn comparatively more heterogeneous landscapes, hares established home ranges in areas with lower road densities compared to the surrounding area, but not in more simple landscapes. Moreover, hares generally avoided main roads and selected for minor roads during the vegetation growth seasons, especially in areas with comparatively less heterogeneous habitat structure. Hares crossed more main roads when moving greater distances, with movement distances being comparatively larger in simpler landscapes.ConclusionsOur findings emphasize that it is important to distinguish between road types, as different roads can have different impacts on animals (e.g., small roads providing foraging opportunities via roadside vegetation and large roads being avoided). Moreover, animals in comparatively more heterogeneous landscapes are better able to adjust their habitat selection to avoid main roads than animals inhabiting simpler landscapes. More generally, homogenous landscapes increase the space use requirements of animals, leading to increased probability of road crossings, which in turn might affect population dynamics via increased road mortality risk.

How do assemblages of epigeal Araneae and Coleoptera respond to changes in habitat structure caused by sugar cane crops in Northern Argentina?

ABSTRACT In Northwest Argentina, nothing is known about the relationship of Araneae and Coleoptera with sugar cane crops. Using pitfall traps in three continuous native forest sites (N) and three native forest windbreaks surrounded by sugar cane crops (W) in the province of Salta, we assessed a)- whether the native diversity of epigeal Araneae and Coleoptera in the Chaco Serrano forest changes as a result of the fragmentation of the habitat caused by the sugar cane plots, and b)- whether the diversity of predatory species increases in native forest windbreaks as a consequence of the contribution of species that come from crops. In the spring of 2006 and the summer of 2007, we collected 599 Araneae and 555 Coleoptera, with community W (S = 132, N = 535) containing much more species but fewer individuals than community N (S = 111, N = 619). We found that the spatial and phenological patterns of the alpha and beta diversities of N were altered in W communities. Thus, habitat fragmentation generated by sugar cane plots led to the local extinction of native Araneae and Coleoptera species. The abundance of generalist Araneae and herbivorous Coleoptera increased in W habitats, but the coprophagous and detritivorous beetles decreased. The diversity of predatory species (Araneae and some Coleoptera) increased in W habitats, although their abundance declined relative to N habitats. Species turnover determined beta diversity between N and W sites; however, between the W sites, nestedness increased and spiders showed a greater loss of species. The spatial heterogeneity between sites, seasons, and habitats had a substantial effect on the composition of the Araneae and Coleoptera assemblages, hence influencing regional diversity. Eight species were habitat indicators, particularly Leprolochus birabeni (Zodariidae), which responds unfavourably to perturbations in the agricultural landscape, and could be deployed as environmental monitors in the Chaco Serrano.

Polygonum criopolitanum Hance Expansion and Its Effects on Overwintering Goose Populations in the Poyang Lake Wetland

Since 2003, Poyang Lake has been showing obvious signs of degradation due to its changed “river-lake” relationship with the Yangtze River. The water level of Poyang Lake decreases continuously in autumn. The distribution elevation of wetland beach vegetation is constantly moving down and the distribution range is constantly expanding. The Polygonum criopolitanum community expansion at 9–12 m elevation (Yellow Sea elevation, the same below) has resulted in a significant decline in areas of mudflat and shallow water, and a significant change in habitat structure for overwintering migratory birds. Combined with field investigation, controlled experiments and statistical modeling were conducted to simulate Polygonum criopolitanum growth at 9–12 m elevation to establish its growth curve, effective growth time, growth rate, and fast-slow turning point. Polygonum criopolitanum growth rate was fastest in the 12 m elevation zone, and reached a maximum in only 22 days. After that, growth rate slowed down and tended to stagnate. Maximum growth rate of Polygonum criopolitanum in 10 and 11 m elevation zones occurred on the 31st and 46th days, respectively. At the inflection point, the Polygonum criopolitanum biomass accumulation rate was fast, then it gradually slowed down until it stopped. Polygonum criopolitanum growth and development at 9–11 m elevation was highly consistent with the arrival of overwintering migratory geese. Polygonum criopolitanum expansion at 9–11 m elevation created fine habitat conditions and rich food resources for populations of Soybean Goose, White Goose, Swan Goose and Cygnet, which was the fundamental reason for the formation of the Duchang Migratory Bird Reserve after 2003. This study is of scientific significance for studies of wetland vegetation community distribution and the promotion of reserve management.

Low flows in a regulated river system are associated with reduced breeding bird abundance and diversity in Yosemite National Park, California

AbstractRiver regulation can alter the magnitude, frequency, duration, and timing of flows, which influences the function of downstream ecosystems. Bird communities can be useful indicators of ecosystem function as individual species respond to varied changes in habitat structure and food availability. We examined the relative importance of different aspects of a regulated flow regime (average daily flow, the number of days flows fell below the 25th percentile, the timing and magnitude of maximum flows, and the inter‐annual duration of flows below the historical median) on predicted bird abundance and diversity using 11 years of data collected within a floodplain meadow system located downstream of Hetch Hetchy Reservoir in Yosemite National Park, California. We found that prolonged periods of low flows were negatively associated with the number of breeding birds detected, as well as the species richness of the breeding bird community. Species richness was also negatively correlated with delays in spring runoff delivery. We opportunistically looked at the same hydrologic variables in a parallel unregulated system, the Merced River through Yosemite Valley, and did not find the same strong relationship with bird community data. This suggests that the dam may be exacerbating the effects of drought.

Mitigating the effect of linear infrastructure on arboreal mammals in dense forest: A canopy bridge trial

SummaryRoads and other linear infrastructure create treeless gaps that can limit the movement of non‐flying, arboreal animals. These negative effects are particularly strong in dense forests, where even narrow infrastructure corridors represent a significant change in habitat structure. Artificial canopy bridges are an increasingly common approach to mitigating the barrier effect of roads and other linear infrastructure on the movement of arboreal mammals; however, questions remain about the success of various designs for different species. Here we conduct an experimental evaluation of the response of a critically endangered possum, Leadbeater's Possum (Gymnobelideus leadbeateri), to two artificial canopy bridge designs: single‐rope bridges and ladder bridges. We found that both bridges were used by Leadbeater's Possum and five other species of arboreal marsupial to cross narrow, forestry roads. However, Leadbeater's Possums crossed ladder bridges 13 times more often than the single‐rope design (average of 564.5 and 41.75 crossings per design respectively). Radiotelemetry conducted on four Leadbeater's Possums prior to bridge installation detected no road crossings, providing preliminary evidence that the bridges improved cross‐road movement. Ladder bridges appear to be the better design choice for a wider range of arboreal marsupials as they were used more frequently, offer greater stability, and provide better predator avoidance than single‐rope designs.

Effects of habitat degradation on bird functional diversity: A field test in the Valdivian rainforest

Deforestation and forest degradation are among the main biodiversity loss drivers worldwide. The expansion of productive activities, such as forest plantations, often results in the loss and degradation of native forests, affecting native species in many ways. While many studies have assessed the effects of habitat degradation on taxonomic diversity, the effects on functional diversity have been little explored. Functional diversity provides a robust framework for understanding how anthropogenic disturbance changes biodiversity. We assessed how bird functional diversity changes along a habitat degradation gradient in the Valdivian rainforests (southern Chile). We used four functional diversity indices and compared four habitat types (old-growth, secondary, and logged native forests and exotic plantations) to assess how functional diversity changes depending on habitat structure and bird life history, and behavioral traits. We found that most functional diversity differences occur between old growth and secondary native forests, being the latter the less functionally diverse habitat. Further, secondary forests lack natural tree cavities, and birds nesting there are more prone to be affected by brood parasitism. Changes in habitat structure seem to be determinant for bird functional diversity along a habitat degradation gradient. Therefore, habitat degradation can lead to functional homogenization beyond changes in species richness or abundance, with less evident ecological consequences.

Interrelationships between fire, habitat, and mammals in a fragmented heathy woodland

Altered fire regimes threaten biodiversity, but there is limited understanding of the mechanisms driving population declines. Relationships between mammal occurrence and time since fire can be unclear because mammals respond directly to changes in habitat structure rather than time since fire per se, and patterns of regeneration can be highly variable. Previous studies have examined how mammals respond to time since fire and habitat structure separately, but rarely considered the three factors together. Furthermore, fires may interact with other threats such as habitat loss and fragmentation, also rarely incorporated into fire studies but known to influence mammal communities. Understanding each of these mechanisms and how they interact is critical for using fire effectively in conservation.We simultaneously related ground-dwelling mammal species activity to habitat structure, habitat structure to post-fire vegetation growth stage, and species activity to growth stage and landscape structure (extent of heathy woodland vegetation) using structural equation models (SEMs). This allowed us to find direct effects of growth stage on mammals, indirect effects mediated by habitat structure, and additional effects of landscape structure.Understorey cover, litter depth, and coarse woody debris responded to growth stage and were important contributors in all SEMs. Four of seven mammal species responded to at least one habitat structure variable. None of the mammal species were related directly to growth stage, but mammals were indirectly related to growth stage through the mediating influence of habitat structure. For example, western grey kangaroos were linked to recently burnt sites, but only through their negative association with litter depth. Extent of heathy woodland vegetation was also an important driver of mammal activity and was related to all but one species; two species showed a positive relationship, and four negative.Important relationships between fire and ground-dwelling mammals may be overlooked unless changes in important habitat resources are also considered. Fire management planning for fauna conservation should incorporate habitat responses as mammal responses to the fire regime may be mediated by fire-driven changes in resources. Knowing how time since fire affects important habitat structures can improve the effectiveness of using fire to manipulate these to support mammal species. Our results will help land managers understand direct and indirect effects of fire in a landscape where multiple drivers threaten biodiversity, and guide the use of prescribed fire to promote aspects of habitat structure that benefit mammals.

Subarctic afforestation: Effects of forest plantations on ground‐nesting birds in lowland Iceland

Abstract Planting forests is a commonly suggested measure to mitigate climate change. The resulting changes in habitat structure can greatly influence the diversity and abundance of pre‐existing wildlife. Understanding these consequences is key for avoiding unintended impacts of afforestation on habitats and populations of conservation concern. Afforestation in lowland Iceland has been gaining momentum in recent years and further increases are planned. Iceland supports internationally important breeding populations of several ground‐nesting, migratory bird species that mostly breed in open habitats. If afforestation impacts the distribution and abundance of these species, the consequences may be apparent throughout their non‐breeding ranges across Europe and Africa. To quantify the effects of plantation forests on the abundance and distribution of ground‐nesting birds (in particular waders, Charadriiformes), surveys were conducted on 161 transects (surrounding 118 plantations) perpendicular to forest edges throughout Iceland. The resulting variation in density with distance from plantation was used to estimate the likely changes in bird numbers resulting from future afforestation plans, and to explore the potential effects of different planting configuration (size and number of forest patches) scenarios. Of seven wader species, densities of five (golden plover Pluvialis apricaria, whimbrel Numenius phaeopus, oystercatcher Haematopus ostralegus, dunlin Calidris alpina and black‐tailed godwit Limosa limosa) in the 200 m surrounding plantations were just under half of those further away (up to 700 m). Redshank Tringa totanus densities were lowest ≤150 m from the plantation edge while snipe Gallinago gallinago densities were 50% higher close to plantations (0–50 m) than further away (51–700 m), and no consistent effects of plantation height, diameter, density or type were identified. Plantations are typically small and widespread, and simulated scenarios indicated that total declines in bird abundance resulting from planting trees in one large block (1,000 ha) could result in only ~11% of the declines predicted from planting multiple small blocks (1 ha) in similar habitats. Synthesis and application. Planting forests in open landscapes can have severe impacts on populations of ground‐nesting birds, which emphasizes the need for strategic planning of tree‐planting schemes. Given Iceland's statutory commitments to species protection and the huge contribution of Iceland to global migratory bird flyways, these are challenges that must be addressed quickly, before population‐level impacts are observed across migratory ranges.

Detectability of birds under different sampling efforts and during the breeding season: a case study from Central Europe

During the years 2019 and 2020, I conducted a bird survey transect in the Bohemian Forest. I did not record any changes in habitat structure or weather conditions between the two years. The two surveys differed in sampling effort, which was significantly lower in 2020 (n = 5 visits) than 2019 (n = 14 visits). I found that sampling effort affected the assessment of avian community diversity but did not affect the total number of individuals recorded. I also recorded a similar pattern in the cumulative number of species between the two breeding seasons, but 80% of species were recorded ten days earlier with the higher sampling effort. In the year with the lower sampling effort, I recorded fewer species than in the year with higher sampling effort. In both study periods, avian community diversity peaked during May and June. These results suggest that even a sampling effort three times lower is still sufficient to detect most species if the minimal number of visits are conducted. The pattern of detectability during the breeding season differed significantly among species. Most species (n = 24) showed a decreasing linear detectability throughout the summer months (e.g. Turdidae or Muscicapidae), most probably due to their breeding activities. In two species (willow tit Poecile montanus and European goldfinch Carduelis carduelis), this linear relationship was reversed, probably due to singing of young birds from the previous breeding season and the effect of the autumn equinox on birdsong activity. Many species (n = 21) did not show any trend and the rest, mainly migratory species, showed non-linear relationships with the peak in the middle of the breeding season. The differences in trends of detectability (i.e. song activity) among bird species are therefore directly linked with their life history.

Recreational caving impacts of visitors in a high-altitude cave in Bolivian Andes: main effects on microhabitat structure and faunal distribution

The cave’s physical environment can be affected by tourism activities but only a few studies evaluated how recreational use may affect the cave fauna, mainly in caves with a low number of visitors per year. To test the hypothesis that recreational use led to changes in habitat structure and invertebrate diversity, distinct scales along a cave were analyzed. Distinct areas with and without human visitation were analyzed and transects (10 x 3 m) and quadrats (1 x 1 m) were used to access the invertebrate communities and environmental traits. Thirty-two invertebrate species were recorded, among which six are troglobitic. The similarity of non- troglobitic species differed between the visited and non-visited areas. Substrate composition inside transects differed between the two areas and the differences were higher in the percentage of matrix rock and fine sediments. The distance from the entrance influenced the similarity of non-troglobitic species while troglobitic fauna responded to the proportion of sandy sediment. Inside quadrats, both matrix rock and fine sediments influenced the similarity of non-troglobitic species. Similarity of non-troglobitic species in the visited area was explained by the proportion of matrix rock in transects and quadrats. The proportion of cobbles influenced the similarity of non-troglobitic species in quadrats in the non-visited area. The non-troglobitic species richness inside quadrants was positively related to the amount of guano, wood, fine sediment, boulders, cobbles, matrix rock, sand sediment, and plant debris. Differentiation in habitat structure and faunal composition between the two areas seems to be an effect of distance from the entrance and spatial heterogeneity, but not recreational activities.