Negative Effects Of Habitat Loss Research Articles

Landscape heterogeneity can partially offset negative effects of habitat loss on mammalian biodiversity in agroecosystems

Abstract Intensive, large‐scale agriculture promotes the conversion of natural habitats and diversified crops into monocultures, decreasing both native vegetation cover and landscape heterogeneity, leading to landscape simplification. Yet, a key knowledge gap persists on the relative impacts of the loss of native vegetation and landscape heterogeneity on biodiversity. Addressing this gap is pressing to support policies that conciliate agricultural production and biodiversity conservation and to move forward some scientific controversies, as the ‘land sharing versus land sparing’ and ‘habitat loss versus fragmentation’ debates. Through a hierarchical sampling design that maximised variation, while minimising correlation, between landscape heterogeneity and native vegetation cover, we recorded the occurrence of medium and large‐bodied mammals in native vegetation and agricultural areas of 55 landscapes in a global conservation hotspot and a key commodity production area—the Brazilian Savanna, Cerrado. We compared simple, additive and interactive models to investigate the effects of landscape heterogeneity and native vegetation cover on richness and composition of native and invasive mammals. Native and invasive mammal communities were affected by both native vegetation cover and landscape heterogeneity, although the effects of the first was stronger than the later. Both aspects had positive effects on native species richness and negative effects on invasive species richness, indicating that the loss of native vegetation and the reduction in landscape heterogeneity lead to biotic homogenisation. Yet, while landscape heterogeneity benefited most native species, the direction of its effect varied among invasive species and depended on native vegetation cover. Synthesis and applications. Besides reducing habitat loss, avoiding landscape homogenisation is key for conciliating agricultural production and biodiversity conservation, pointing to the relevance of policies encouraging crop diversification. As increasing landscape heterogeneity can in part compensate the negative effects of losing native habitat on biodiversity in agroecosystems, policies can gain feasibility by adjusting the balance between native vegetation cover and landscape heterogeneity according to what best suits local restraints and demands.

Skewed morph ratios lead to lower genetic diversity of the heterostylous Primula veris in fragmented grasslands.

Populations of heterostylous plant species are ideally composed of equal frequencies of two (distylous) or three (tristylous) morphologically different floral morphs. Intra-morph incompatibility helps to avoid inbreeding and to maintain genetic diversity, supporting plant fitness and long-term viability. Habitat fragmentation can lead to skewed morph ratios and thereby reduce the abundance of compatible mates. This, in turn, can result in a loss of genetic diversity. We tested whether the genetic diversity of heterostylous plants is affected by morph ratio bias using populations of the distylous grassland plant Primula veris in recently fragmented grasslands. We recorded morph frequencies and population sizes in 30 study populations of P. veris on two Estonian islands characterised by different degrees of habitat fragmentation. Examining variation of thousands of single nucleotide polymorphisms (SNPs) and heterostyly-specific genetic markers, we quantified overall and morph-specific genetic diversity and differentiation in these populations. Morph frequencies deviated more in smaller populations. Skewed morph ratios had a negative effect on the genetic diversity of P. veris in more fragmented grasslands. In the populations of better-connected grassland system, genetic differentiation among S-morphs was higher than among L-morphs. Our study shows that deviations from morph balance are stronger in small populations and have a negative impact on the genetic diversity of the distylous plant P. veris. Together with the direct negative effects of habitat loss and decreased population size on the genetic diversity of plants, morph ratio bias may intensify the process of genetic erosion, thus exacerbating the local extinction of heterostylous species.

Cover Picture and Issue Information

Functional EcologyVolume 37, Issue 3 p. 473-475 COVER PICTURE AND ISSUE INFORMATIONFree Access Cover Picture and Issue Information First published: 02 March 2023 https://doi.org/10.1111/1365-2435.14073AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract Flowering plants need pollinators to transfer pollen, such as those pictured on this Tamarix chinensis (Credit: Le Jiao). The movement behavior and strategy of pollinators significantly affects pollination success and the subsequent seed set, especially for plant populations that are faced with habitat loss. Jiao et al. 2022 (DOI: 10.1111/1365-2435.14252) simulated two key stages of pollinator movement during the pollination process: a foraging response stage towards plant patches mediated by floral scents, and an individual dispersal stage between plant patches mediated by a densitydependent dispersal strategy. Plant reproduction was negatively affected by habitat loss, as the emission amount of floral scents and the foraging success rate of pollinators decreased in the context of habitat loss. However, the pollinator movement strategy (i.e. density-dependent dispersal strategy) can help mitigate adverse impacts by promoting visitation to suboptimal plant patches, thereby improving the persistence of the plant population in fragmented landscapes. Altogether, this simulation result points to the positive role of pollinator movement strategy in alleviating the negative effects of habitat loss on plant reproduction. Volume37, Issue3March 2023Pages 473-475 RelatedInformation

Forest edges increase pollinator network robustness to extinction with declining area

Edge effects often exacerbate the negative effects of habitat loss on biodiversity. In forested ecosystems, however, many pollinators actually prefer open sunny conditions created by edge disturbances. We tested the hypothesis that forest edges have a positive buffering effect on plant-pollinator interaction networks in the face of declining forest area. In a fragmented land-bridge island system, we recorded ~20,000 plant-pollinator interactions on 41 islands over 3 yr. We show that plant richness and floral resources decline with decreasing forest area at both interior and edge sites, but edges maintain 10-fold higher pollinator abundance and richness regardless of area loss. Edge networks contain highly specialized species, with higher nestedness and lower modularity than interior networks, maintaining high robustness to extinction following area loss while forest interior networks collapse. Anthropogenic forest edges benefit community diversity and network robustness to extinction in the absence of natural gap-phase dynamics in small degraded forest remnants.

Resident wild koalas show resilience to large-scale translocation of bushfire-rescued koalas.

Wildlife translocation is increasingly utilized as a conservation management action, to mitigate the immediate negative effects of habitat loss and fragmentation (e.g. from land clearing or bushfires). Previous research has shown that stress responses can help or hinder survival in translocated wildlife and determine the efficacy of translocation as a conservation action. Yet these translocated animals are only one side of the equation, with translocation also potentially impacting the animals in the recipient population. We measured physiological markers of stress (faecal cortisol metabolite concentrations and neutrophil-lymphocyte ratios) and assessed health condition in a wild koala population one year after a major translocation of bushfire-rescued koalas on Kangaroo Island. We expected to find a high population density at the site (>0.75 koalas per hectare) and that resident koalas would show signs of chronic stress and ill health as a result of territorial conflict over food trees and reproductive opportunities. In contrast, we found that only one-fifth of the population remaining at the site were translocated koalas. The overall population density was also much lower (0.21 koalas per hectare) than anticipated. With no evidence of mass mortality at the site, we suggest that the majority of translocated koalas dispersed away from the site. Our stress marker measurements did not differ between the wild koalas and a sample of captive (non-display) koalas at the nearby Kangaroo Island Wildlife Park and were generally low compared to other studies. Veterinary examinations found that most koalas were in good body condition with very few diagnostic indicators of systemic ill health. Overall, our results suggest that, if there is adequate landscape-scale habitat connectivity and opportunity for dispersal, translocated koalas are likely to disperse from the site of release, with limited impacts on recipient koala populations at translocation release sites.

Habitat loss shapes the structure and species roles in tropical plant–frugivore networks

Habitat loss is a global threat to biodiversity with pervasive effects on species and populations. These impacts may generate cascading effects on ecological processes propagating across ecological networks. Thus, understanding how habitat loss affects ecological networks is fundamental for conservation. We used a database of 25 plant–frugivore networks distributed across the whole Brazilian Atlantic Forest to understand how landscape‐scale habitat loss shapes network structure, robustness, species role and traits related to seed dispersal. We compared whether these network properties have linear or non‐linear relationships and used centrality metrics and indirect effects to evaluate if habitat loss change the role of species in plant–frugivore networks. We found linear and non‐linear relationships with negative effects of habitat loss on the network structure. As a consequence of shifts in species richness and number of links, the number of interactions and the proportion of possible interactions observed (connectance) were negatively associated with habitat loss. In contrast, nestedness increased with habitat loss. Network robustness, mean bill width and mean seed size were not significantly related to habitat loss. In addition to changes in interaction patterns at network level, habitat loss also favors changes in interaction among species, shifting the species playing central roles in network organization or contributing to indirect effects in the networks. In forested landscapes, obligate frugivores are the main central species in the network, and the ones potentially contributing to indirect effects, while in deforested landscapes these roles are fulfilled by occasional frugivores. Thus, our results emphasize the widespread effect of habitat loss on plant–frugivore systems, adding evidence that its pervasive effects on biodiversity also proliferate on mutualistic interactions with negative consequences for seed dispersal that potentially go beyond the direct pairs of interacting species.

Foraging behaviour and patch size distribution jointly determine population dynamics in fragmented landscapes.

Increased fragmentation caused by habitat loss represents a major threat to the persistence of animal populations. How fragmentation affects populations depends on the rate at which individuals move between spatially separated patches. Whereas negative effects of habitat loss on biodiversity are well known, the effects of fragmentation per se on population dynamics and ecosystem stability remain less well understood. Here, we use a spatially explicit predator-prey model to investigate how the interplay between fragmentation and optimal foraging behaviour affects predator-prey interactions and, subsequently, ecosystem stability. We study systems wherein prey occupies isolated patches and are consumed by predators that disperse following Lévy random walks. Our results show that the Lévy exponent and the degree of fragmentation jointly determine coexistence probabilities. In highly fragmented landscapes, Brownian and ballistic predators go extinct and only scale-free predators can coexist with prey. Furthermore, our results confirm that predation causes irreversible habitat loss in fragmented landscapes owing to overexploitation of smaller patches of prey. Moreover, we show that predator dispersal can reduce, but not prevent or minimize, the amount of lost habitat. Our results suggest that integrating optimal foraging theory into population and landscape ecology is crucial to assessing the impact of fragmentation on biodiversity and ecosystem stability.

Grassland fragmentation affects declining tallgrass prairie birds most where large amounts of grassland remain

Habitat fragmentation can exacerbate the negative effects of habitat loss for some species. Mitigating fragmentation is difficult, however, because population responses depend on species-level traits (e.g., dispersal ability, edge sensitivity) and landscape context (e.g., habitat amount). Thus, conservation requires determining not only if, but also where and why, fragmentation matters. We aimed to determine if and where grassland fragmentation affects tallgrass prairie birds, which have declined precipitously due to land-use change. We surveyed four edge-sensitive species at 2250 sites (10,291 total surveys) across eastern Kansas, USA, over two breeding seasons. We assessed how the occurrence of each species varied with different levels of fragmentation in local landscapes comprising different grassland amounts. Fragmentation clearly mediated positive relationships between occurrence probability and grassland area for all four species. The direct effect of fragmentation was greater than that of grassland area for two species. Moreover, fragmentation reduced the occurrence of each species by at least half in some contexts. Fragmentation effects were most pronounced in landscapes comprising ~ 50–90% grassland, and less pronounced or absent in landscapes comprising < 50% grassland, which were occupied relatively infrequently. Conservation efforts should minimize ‘perforation’ of large grasslands by woody vegetation and land development, which not only replace grassland, but also often create disproportionately large amounts of grassland edge. Identifying mechanisms responsible for edge effects could further inform species-level conservation. Our results counter assertions that fragmentation does not matter or only matters when habitat is scarce or for species that are dispersal limited.

Understanding the Importance of Dynamic Landscape Connectivity

Landscape connectivity is increasingly promoted as a conservation tool to combat the negative effects of habitat loss, fragmentation, and climate change. Given its importance as a key conservation strategy, connectivity science is a rapidly growing discipline. However, most landscape connectivity models consider connectivity for only a single snapshot in time, despite the widespread recognition that landscapes and ecological processes are dynamic. In this paper, we discuss the emergence of dynamic connectivity and the importance of including dynamism in connectivity models and assessments. We outline dynamic processes for both structural and functional connectivity at multiple spatiotemporal scales and provide examples of modeling approaches at each of these scales. We highlight the unique challenges that accompany the adoption of dynamic connectivity for conservation management and planning in the context of traditional conservation prioritization approaches. With the increased availability of time series and species movement data, computational capacity, and an expanding number of empirical examples in the literature, incorporating dynamic processes into connectivity models is more feasible than ever. Here, we articulate how dynamism is an intrinsic component of connectivity and integral to the future of connectivity science.

Are Habitat Fragmentation Effects Stronger in Marine Systems? A Review and Meta-analysis

The importance of habitat fragmentation in driving biodiversity loss has been recently debated. While the negative effects of habitat loss are well-documented, the effects of habitat fragmentation independent of habitat loss (e.g., habitat configuration) are more equivocal. Marine ecosystems have been underrepresented in past reviews, yet may differ fundamentally from terrestrial systems in their responses to habitat fragmentation because of the nature of energy/material flow, open population structure of most marine species, and narrow habitat extents. We conducted a systematic literature review and meta-analysis on the effects of habitat fragmentation in marine ecosystems. In our review of 180 studies from 28 articles, we found that habitat fragmentation effects were more often negative than positive, although the overall mean effect did not differ from zero. Interestingly, the mean effect was positive when the response was a measure of abundance, biodiversity, or population/ecosystem stability. Habitat fragmentation had overwhelmingly negative effects when it involved hydrological fragmentation. We found some support for the fragmentation threshold hypothesis via a weak negative relationship between habitat percent cover in the landscape and the habitat fragmentation effect. Results of this review on the effects of habitat fragmentation in marine ecosystems are largely consistent with another recent review finding that habitat fragmentation (independent of habitat loss) does not have consistent, negative impacts on biodiversity, and in many cases may increase biodiversity. Future work should focus on factors driving this variability and employ multi-scale frameworks to test for congruence between patch- and landscape-scale studies.

Breeding range shift of the red-crowned crane (Grus japonensis) under climate change.

The red-crowned crane (Grus japonensis) is an endangered species listed by International Union for Conservation of Nature (IUCN) HARRIS J (2013). The largest population of this species is distributed mainly in China and Russia, which is called continental population SU L (2012)-Curt D (1996). This population is migratory, which migrates from its breeding range located in Northeast China and Southern Russia, to the wintering range in the south of China to spend the winter every year. The breeding range of this species is critical for red-crowned crane to survive and maintain its population. Previous studies showed the negative effects of habitat loss and degradation on the breeding area of red-crowned crane Ma Z (1998), Claire M (2019). Climate change may also threat the survival of this endangered species. Previous studies investigated the impacts of climate change on the breeding range or wintering range in China Wu (2012), [1]. However, no study was conducted to assess the potential impacts of climate change on the whole breeding range of this species. Here, we used bioclimatic niche modeling to predict the potential breeding range of red-crowned crane under current climate conditions and project onto future climate change scenarios. Our results show that the breeding range of the continental population of red-crowned crane will shift northward over this century and lose almost all of its current actual breeding range. The climate change will also change the country owning the largest portion of breeding range from China to Russia, suggesting that Russia should take more responsibility to preserve this endangered species in the future.

The risk of ignoring fear: underestimating the effects of habitat loss and fragmentation on biodiversity

CONTEXT: Habitat loss and fragmentation threaten species not only through structural landscape changes and resource reduction, but also through modifications to species’ interactions. In particular, the observed consequences of landscape changes for predator–prey interactions often lack a clear pattern, indicating a range of complex behavioral adaptations and interactions. One potentially important contributing factor shaping these consequences is perceived predation risk and hence fear, which is rarely explicitly addressed in studies on habitat modification. OBJECTIVES: We investigated how fear changes prey community structures under habitat loss and fragmentation and identified habitat properties driving these changes. METHODS: We applied a spatially-explicit, individual-based model which simulates home range formation of a mammalian prey community based on food availability and perceived predation risk. With the model we predicted prey community structures under different landscape scenarios. RESULTS: Fear intensified the negative effects of habitat loss and fragmentation on prey communities, causing a non-proportional diversity loss of up to 30%. Shifts in community composition from large to small animals were reinforced. The highest prey diversity was supported in landscapes with non-fragmented safe areas. Our findings highlight the importance of fear in shaping prey community structures under conditions of landscape change. CONCLUSIONS: Our modelling approach addresses the mechanisms that link individual space use with community structure. It reveals the key role played by the spatial distribution of safe patches in mitigating the negative effects of landscape changes. Thereby, it supports modern conservation efforts that go beyond single-species approaches by taking changes in community structure into account.

The key role of protection status in safeguarding the ecological functions of some Neotropical mammals

Protected areas can mediate negative effects of habitat loss and human-related pressures on key ecological groups. However, different protected area categories can vary substantially in their degree of enforcement, which may ensure different levels of effectiveness for biodiversity protection. Because little attempt has been made to quantify this, we investigated the protection effectiveness of different levels of protection (low, intermediate, and high) in maintaining the ecological functions of mammalian species. We assessed this on a selection of five species with varying ecological functions: nine-banded armadillo (insectivore), paca (seed disperser), tayra (omnivore), ocelot (carnivore), and collared peccary (seed predator). Their occupancy probability and the integrity of their ecological functions were estimated and spatialized across landscapes at all protection levels (low, intermediate, and high). In addition, we estimated how many of these species were maintained in each protection status using a minimum of 35% occupancy threshold for each. Our results indicated that higher protection statuses can hold more ecological functions of these mammalian species than areas with lower protection levels. Ocelot and paca heavily relied on areas with higher protection, which can impact the overall ecosystem functioning and ecological services of less protected areas, since these are species performing unique roles in our landscape (mixed-sized prey carnivory and large-sized seed dispersal, respectively). Our study suggests that the degrees of protection can influence the area effectiveness in maintaining certain mammalian species and their ecological functions and ecosystem services. Therefore, management strategies and degree of enforcement should be carefully planned when assigning areas for conservation to ensure the conservation of more sensitive species and preserve more ecological functions.

Habitat loss causes non-linear genetic erosion in specialist species

Habitat loss can lead to non-linear declines in species abundance once the amount of landscape-wide habitat is reduced to a critical value. Previous studies have suggested that such non-linear responses to landscape-wide habitat loss might also exist in genetic variation, and an in-depth understanding of non-linear habitat loss effects on all levels of biodiversity levels is vital to take appropriate conservation actions.Using individual-based simulations we evaluated the existence of generic non-linear responses in three different response variables and across different combinations of traits related to dispersal and population density. We simulated habitat loss scenarios by incrementally reducing the landscape-wide habitat amount within a previously undisturbed landscape and monitored population abundance, genetic diversity and differentiation of populations within constant sampling areas over time. We found aside from population abundance, genetic variation also responded non-linearly to habitat loss across all scenarios. Importantly, the populations that persisted in remaining habitat fragments experienced genetic erosion before a noticeable effect on local abundance occurred. The observed increase in genetic differentiation and the decrease in genetic diversity of remaining populations are likely caused by the indirect effects of landscape-wide habitat loss on effective patch isolation. Thus, genetic data might have the potential to detect indirect effects of landscape-wide habitat loss before it directly affects the size of a population. Since indirect effects of habitat loss might go unnoticed when extinction risk is estimated from abundance data alone, we argue that an improved understanding of genetic effects is crucial to anticipate and ultimately prevent the negative effects of habitat loss.

Butterflies in Swedish grasslands benefit from forest and respond to landscape composition at different spatial scales

ContextLoss and fragmentation of semi-natural grasslands has critically affected many butterfly species in Europe. Habitat area and isolation can have strong effects on the local biodiversity but species may also be strongly affected by the surrounding matrix.ObjectivesWe explored how different land cover types in the landscape explained the occurrence of butterfly species in semi-natural grasslands.MethodsUsing data from 476 semi-natural grasslands in Sweden, we analysed the effect of matrix composition on species richness and occurrence. Additionally, we analysed at which spatial scales butterflies responded to matrix types (forests, semi-natural grasslands, arable land and water).ResultsForest cover showed the strongest positive effect on species richness, followed by semi-natural grasslands. Forest also had a positive effect on red-listed species at local scales. Responses to matrix composition were highly species-specific. The majority of the 30 most common species showed strong positive responses to the amount of forest cover within 200–500 m. There was a smaller group of species showing a positive response to arable land cover within 500–2000 m. Thirteen species showed positive responses to the amount of semi-natural grasslands, generally at larger scales (10–30 km).ConclusionsOur study showed that surrounding forest is beneficial for many grassland butterfly species and that forests might mitigate the negative effects of habitat loss caused by agricultural intensification. Also, semi-natural grasslands were an important factor for species richness at larger spatial scales, indicating that a landscape consisting mainly of supporting habitats (i.e. forests) are insufficient to sustain a rich butterfly fauna.

Habitat fragmentation affects individual condition: evidence from small mammals of the Brazilian Atlantic Forest

Habitat loss and fragmentation are likely to affect individual condition as they usually alter the quality of habitat. However, responses of individuals of different species to these processes may be subtle and difficult to detect, despite that such responses may reveal interesting and diverse strategies of persistence of species in fragmented landscapes. Here, we used model selection to 1) compare the body condition (Scaled Mass Index) of 2 Neotropical marsupials (Didelphis aurita and Philander frenatus) from 6 continuous forest sites and 25 forest fragments, and 2) determine whether local habitat structure and landscape and temporal factors affect body condition in forest fragments. Body condition of both species was lower in forest fragments compared to continuous forest sites, but only in the super-humid season for D. aurita and in the humid season for P. frenatus. When only forest fragments were compared, body condition of D. aurita was higher in the humid season, in sites with fewer Cecropia trees and water courses, lower percent forest cover, and surrounded by a mixed matrix (plantation and cattle ranching), or located in small rural properties. Body condition of P. frenatus was slightly higher in the super-humid season, in sites surrounded by a mixed matrix, with fewer Cecropia trees and water courses, more lianas, and greater percent forest cover. Our results revealed negative effects of habitat loss and fragmentation on both species, but also different responses of each species to local extrinsic environmental factors. We suggest that body condition should not be used as a direct indicator of animal fitness or habitat quality. Nonetheless, body condition may still reveal subtle and previously undetected responses of species to habitat disturbance and fragmentation.

Enhancing conservation network design with graph-theory and a measure of protected area effectiveness: Refining wildlife corridors in Belize, Central America

Maintaining connectivity among remaining natural areas has become increasingly important to ameliorate the negative effects of habitat loss and fragmentation on wildlife populations. Early corridor networks were based on structural connectivity (i.e. habitat structure) and designed to connect protected areas. In recent decades, many methods have been developed to increase the ecological realism of such corridor design to avoid misguided management. However, the multitude and complexity of methods can be a hurdle for conservation planners. Here, we combine a limited set of multiple methods to present a connectivity analysis framework that produces repeatable, intuitive, and ecologically relevant connectivity estimates. We use a modified habitat suitability analysis, accounting for protected area effectiveness, as a starting point for least-cost corridor estimates, and evaluate the network using graph theory. We apply the framework to an existing corridor network in Belize, Central America, by estimating potential functional connectivity for white-lipped peccaries Tayassu pecari between systematically identified core patches. We found that forest productivity and protected area effectiveness were important predictors of habitat suitability for white-lipped peccaries. The graph-theoretic network analyses identified particularly important core areas for overall landscape connectivity and indicated potentially weak links in the existing network, while the least-cost corridor outlines indicated general areas where the implementation of connectivity-enhancing measures could strengthen such weak links. With this study, we provide a framework to improve the scientific rigour, ecological meaningfulness, and conservation relevance of applied corridor network design.

Experimental small‐scale flower patches increase species density but not abundance of small urban bees

Abstract Large flower plantings are often used to combat negative effects of habitat loss on pollinators, but whether these floral additions are effective at smaller scales remains unclear, particularly in urban settings. To test the effectiveness of small‐scale floral additions on enhancing urban bee populations, as well as their impact from 1 year to the next, different quantities of potted sweet alyssum (Lobularia maritima) flowers were placed across sites in Ann Arbor, Michigan for two consecutive years and the resulting Halictid bee visitors were monitored. Overall, we found the number of flowers added at the local level was significantly and positively correlated with small Halictid bee abundance and species density in an urban landscape. At smaller flower quantities, dynamics were clearly linear, where incremental increases in number of flowers showed significant increases in bee abundance and species density. At larger quantities of floral additions, however, dynamics were nonlinear in that incremental increases in flower quantity had no effect on bee abundance and highly variable effects on bee species density. When comparing the change in small Halictid bee abundance and species density from 1 year to the next, we found a significant increase in bee species density in the second year of small‐scale floral additions, but no significant difference in bee abundance. Synthesis and applications. Our results show that small flower plantings can have positive effects on small bee communities in urban systems even over a short period of time and therefore confirm that encouraging citizens to plant flowers can be an effective conservation strategy for certain urban pollinator populations. In addition, our finding that smaller flower plantings may have higher impacts on small pollinators than larger plantings suggests resource managers interested in pollinator conservation should consider spreading multiple, smaller floral plantings across the urban landscape, rather than pooling all resources into one large flower patch.

Closing the gaps for animal seed dispersal: Separating the effects of habitat loss on dispersal distances and seed aggregation.

Habitat loss can alter animal movements and disrupt animal seed dispersal mutualisms; however, its effects on spatial patterns of seed dispersal are not well understood. To explore the effects of habitat loss on seed dispersal distances and seed dispersion (aggregation), we created a spatially explicit, individual‐based model of an animal dispersing seeds (SEADS—Spatially Explicit Animal Dispersal of Seeds) in a theoretical landscape of 0%–90% habitat loss based on three animal traits: movement distance, gut retention time, and time between movements. Our model design had three objectives: to determine the effects of (1) animal traits and (2) habitat loss on seed dispersal distances and dispersion and (3) determine how animal traits could mitigate the negative effects of habitat loss on these variables. SEADS results revealed a complex interaction involving all animal traits and habitat loss on dispersal distances and dispersion, driven by a novel underlying mechanism of fragment entrapment. Unexpectedly, intermediate habitat loss could increase dispersal distances and dispersion relative to low and high habitat loss for some combinations of animal traits. At intermediate habitat loss, movement between patches was common, and increased dispersal distances and dispersion compared to continuous habitats because animals did not stop in spaces between fragments. However, movement between patches was reduced at higher habitat loss as animals became trapped in fragments, often near the parent plant, and dispersed seeds in aggregated patterns. As movement distance increased, low time between movements and high gut retention time combinations permitted more movement to adjacent patches than other combinations of animal traits. Because habitat loss affects movement in a nonlinear fashion under some conditions, future empirical tests would benefit from comparisons across landscapes with more than two levels of fragmentation.

The effect of roads on edge permeability and movement patterns for small mammals: a case study with Montane Akodont

Increased edge density is among the main negative effects of habitat loss and fragmentation. Roads are linear infrastructures that may promote barrier effects due to disturbance and mortality effects. We hypothesized that edges of habitat patches bordered by roads are less permeable than roadless edges. We tested whether edge permeability and avoidance are influenced by the presence of paved and dirt roads bordering habitat patches, relatively to roadless edges. We translocated 55 montane akodonts (Akodon montensis) from the interior of vegetation remnants to their edges, and tracked fine-scale movements using spool-and-line devices. Edges were bordered by dirt roads (n = 12 mice), paved roads (n = 21) or were not bordered by roads (n = 22). We assessed edge permeability by comparing the number of tracks with crossings, and by comparing the empirical data to simulated correlated random walks. We also assessed edge avoidance by comparing the net direction travelled and net displacement from edge. No edge crossings were recorded in roaded edges, whereas 36% of tracks in roadless edges crossed the edge at least once. Simulations indicated a significantly lower permeability of roaded edges, while the observed number of crossings in roadless edges was within the expected range. We found no evidence of higher avoidance of roaded edges, as both net direction travelled and displacement were similar across edge types. Roads decreased edge permeability for the montane akodont. This is likely to increase population isolation among vegetation remnants by reducing the structural connectivity in the already fragmented landscape.