Dynamic Mosaic Research Articles

The dynamic mosaic phenotypes of flowering plants

Ecological interaction and adaptation both depend on phenotypic characteristics. In contrast with the common conception of the 'adult' phenotype, plant bodies develop continuously during their lives. Furthermore, the different units (metamers) that comprise plant bodies are not identical copies, but vary extensively within individuals. These characteristics foster recognition of plant phenotypes as dynamic mosaics. We elaborate this conception based largely on a wide-ranging review of developmental, ecological and evolutionary studies of plant reproduction, and identify its utility in the analysis of plant form, function and diversification. An expanded phenotypic conception is warranted because dynamic mosaic features affect plant performance and evolve. Evidence demonstrates that dynamic mosaic phenotypes enable functional ontogeny, division of labour, resource and mating efficiency. In addition, dynamic mosaic features differ between individuals and experience phenotypic selection. Investigation of the characteristics and roles of dynamic and mosaic features of plant phenotypes benefits from considering within-individual variation as a function-valued trait that can be analysed with functional data methods. Phenotypic dynamics and within-individual variation arise despite an individual's genetic uniformity, and develop largely by heterogeneous gene expression and associated hormonal control. These characteristics can be heritable, so that dynamic mosaic phenotypes can evolve and diversify by natural selection.

Widespread and lateralized social brain activity for processing dynamic facial expressions.

Dynamic facial expressions of emotions constitute natural and powerful means of social communication in daily life. A number of previous neuroimaging studies have explored the neural mechanisms underlying the processing of dynamic facial expressions, and indicated the activation of certain social brain regions (e.g., the amygdala) during such tasks. However, the activated brain regions were inconsistent across studies, and their laterality was rarely evaluated. To investigate these issues, we measured brain activity using functional magnetic resonance imaging in a relatively large sample (n = 51) during the observation of dynamic facial expressions of anger and happiness and their corresponding dynamic mosaic images. The observation of dynamic facial expressions, compared with dynamic mosaics, elicited stronger activity in the bilateral posterior cortices, including the inferior occipital gyri, fusiform gyri, and superior temporal sulci. The dynamic facial expressions also activated bilateral limbic regions, including the amygdalae and ventromedial prefrontal cortices, more strongly versus mosaics. In the same manner, activation was found in the right inferior frontal gyrus (IFG) and left cerebellum. Laterality analyses comparing original and flipped images revealed right hemispheric dominance in the superior temporal sulcus and IFG and left hemispheric dominance in the cerebellum. These results indicated that the neural mechanisms underlying processing of dynamic facial expressions include widespread social brain regions associated with perceptual, emotional, and motor functions, and include a clearly lateralized (right cortical and left cerebellar) network like that involved in language processing.

«The Whole World is a Work of Art…» Virginia Woolf's novel «The Waves» (episode I)

The article is devoted to the analysis of "The Waves" (the first episode), where Virginia Woolf, as she admitted, has found her "own style" and tries to bring together the word, visual image, prose, poetry and drama. The artistic concept of "The Waves" is complex, the author rejects a coherent narrative, it is substituted by the impressions of an external world, which are occurring in the consciousness of the coeval characters. Thus the dynamic mosaic of the world is created. The unfolding of the visual narration is amplified with the choir of the characters’ voices, who are communicating constantly not with each other but themselves only. The personages of "The Waves" are inseparable from the artist’s creative imagination whose consciousness is acting, playing with the reader. Therefore the characters are not the only ones who dominate over the recollections of the past moments but the author herself does. And if for the previous ones these memories become the woven threads of personal fate, then for the other – it is the "fabric" she needs to fulfill the pattern of her artwork.Woolf’s speculations about the genre of "The Waves" are under view as well as the scholars’ opinions who read "The Waves" as a metaphorical text, author’s myth of women creativity. Woolf dramatizes the narration organizing the design of ‘The Waves’ as a mirror system where the image of reality is being lost in its endless reflections. It is stated that the aesthetic multilayer structure of "The Waves" has just half-opened by the critics, as a lot of philologists feel unusual "trans-genre" nature of the novel itself and correlate it with the loose genre definitions such as ‘symphonic poem’ or "a series of rhapsodies".

A Landscape-Scale Optimisation Model to Break the Hazardous Fuel Continuum While Maintaining Habitat Quality

Wildfires have demonstrated their destructive powers in several parts of the world in recent years. In an effort to mitigate the hazard of large catastrophic wildfires, a common practice is to reduce fuel loads in the landscape. This can be achieved through prescribed burning or mechanically. Prioritising areas to treat is a challenge for landscape managers. To help deal with this problem, we present a spatially explicit, multiperiod mixed integer programming model. The model is solved to yield a plan to generate a dynamic landscape mosaic that optimally fragments the hazardous fuel continuum while meeting ecosystem considerations. We demonstrate that such a multiperiod plan for fuel management is superior to a myopic strategy. We also show that a range of habitat quality values can be achieved without compromising the optimal fuel reduction objective. This suggests that fuel management plans should also strive to optimise habitat quality. We illustrate how our model can be used to achieve this even in the special case where a faunal species requires mature habitat that is also hazardous from a wildfire perspective. The challenging computational effort required to solve the model can be overcome with either a rolling horizon approach or lexicographically. Typical Australian heathland landscapes are used to illustrate the model but the approach can be implemented to prioritise treatments in any fire-prone landscape where preserving habitat connectivity is a critical constraint.

Flood pulse regulation of bacterioplankton community composition in an Amazonian floodplain lake

Abstract Understanding spatial and temporal dynamics of microbial communities is a central challenge in microbial ecology since microorganisms play a key role in ecosystem functioning and biogeochemical cycles. Amazonian aquatic systems comprise a dynamic mosaic of heterogeneous habits but are understudied and there is limited information about the mechanisms that shape bacterial community composition (BCC). There is a consensus that environmental selection (species sorting) and dispersal processes (source–sink dynamics) act in concert to shape the composition of these communities, but the relative importance of each mechanism may vary dramatically through time and between systems. Applying 16S rRNA gene amplicon high‐throughput sequencing, we studied factors and processes that modulate BCC in an Amazonian floodplain lake and used source‐tracking models to trace the main dispersal sources of microorganisms in the whole floodplain system during a full hydrological cycle. Our source‐tracking models indicated that dispersal processes were predominant, explaining most of the BCC variability throughout the study period. We observed more sources contributing to the sink community during the falling water than rising water period, when contributions from the Solimões River dominated. There was a clear seasonal pattern in BCC, closely related to environmental variables, suggesting that the successful establishment of dispersing bacteria also depends on environmental filtering that is linked to water flow. In summary, source–sink dynamics and species sorting were strongly affected by water exchange and connectivity with the main river that varied throughout the flood pulse cycle. Our results demonstrated the influence of lateral transport and temporal dynamics on BCC in Amazonian floodplain lakes that could ultimately impact regional carbon budgets and biogeochemical cycles.

Seasonal variations in diet composition, diet breadth and dietary overlap between three commercially important fish species within a flood-pulse system: The Tonle Sap Lake (Cambodia).

Tropical lakes and their associated floodplain habitats are dynamic habitat mosaics strongly influenced by seasonal variations in hydrologic conditions. In flood-pulse systems, water level oscillations directly influence the connectivity to floodplain habitats for fish. Here, we aimed to investigate whether seasonal changes in the water level of a flood-pulse system (the Tonle Sap Lake, Cambodia) differentially affect diet breadth and dietary overlap of three common and commercially important fish species (Anabas testudineus, Boesemania microplepis and Notopterus notopterus) presenting important differences in their life-cycle (e.g. seasonal migration). For this purpose, the three fish species were sampled at four locations spread over the lake and their stomach contents extracted for analyses. Dietary differences were investigated across seasons regarding the diet composition and diet breadth of each species as well as the amount of dietary overlap between species. We found that the proportion of empty stomachs changed similarly across seasons for the three species, thus suggesting that ecological differences between species are not sufficient to outweigh the effect of seasonal variations in resource abundance. In contrast, changes in diet composition were species-specific and can be explained by ecological and behavioral differences between species. Diet breadth differed between species in all seasons, except during the wet season, and tended to be higher during the dry season when dietary overlap was the lowest. These variations likely result from changes in the diversity and amount of resources and may lead to habitat use shifts with potential implications for competitive interactions. In particular, increasing connectivity to floodplain habitats may reduce the competitive pressure during the wet season, while resource scarcity during the dry season may constrain individuals to diversify their diet to avoid competition. Overall, our results suggest a considerable plasticity in the feeding behavior of the three species as demonstrated by seasonal variation in both diet breadth and dietary overlap. Such variations can be explained by a number of factors and processes, including changes in resource availability or competitive interactions between individuals for resources, whose relative influence might vary depending on the magnitude and the timing of the flood-pulse driving the connectivity to floodplain habitats. Gaining knowledge on the seasonal evolution of fish’s diet is relevant for fisheries management and conservation and our result could be used to guide aquaculture development in Cambodia.

Geometric interpretation of time-scale dependent sedimentation rates

Empirical rate data show that aggradation and progradation rates are negatively correlated with the duration they are averaged over. This means that we cannot understand deep time sedimentation rates in terms of the abundant rate data we have from modern environments. We are addressing this by investigating how growth of a sediment volume in multiple directions affects time-averaged accumulation rates that do not necessarily measure all directions of growth. We derive a mathematical model from mass-balance considerations of a sedimentary deposit that grows without erosion. We show that the non-linear relationship between the lengths, areas and volumes of growing objects require that time-averaged sedimentation rates are time-scale dependent when a deposit grows in multiple directions. We generate rate compilations from simple synthetic stratigraphies, which show that we can reproduce the empirical rate compilations by requiring only that deposition occur in a dynamic mosaic of sequential patches in which the areal extent of deposition increases with time-scale as described by our mathematical model. Our model has two implications with application in stratigraphic analysis. The first is that it provides a theoretical model of why we cannot expect high stratigraphic completeness if we measure a deposit in fewer directions than it has grown. The second is that it provides a framework by which to attribute anomalies in the stratigraphic completeness of a one-dimensional or two-dimensional sample to scaling effects or erosional hiatuses.

BIOTA CONNECT AQUATIC HABITATS THROUGHOUT FRESHWATER ECOSYSTEM MOSAICS.

Freshwater ecosystems are linked at various spatial and temporal scales by movements of biota adapted to life in water. We review the literature on movements of aquatic organisms that connect different types of freshwater habitats, focusing on linkages from streams and wetlands to downstream waters. Here, streams, wetlands, rivers, lakes, ponds, and other freshwater habitats are viewed as dynamic freshwater ecosystem mosaics (FEMs) that collectively provide the resources needed to sustain aquatic life. Based on existing evidence, it is clear that biotic linkages throughout FEMs have important consequences for biological integrity and biodiversity. All aquatic organisms move within and among FEM components, but differ in the mode, frequency, distance, and timing of their movements. These movements allow biota to recolonize habitats, avoid inbreeding, escape stressors, locate mates, and acquire resources. Cumulatively, these individual movements connect populations within and among FEMs and contribute to local and regional diversity, resilience to disturbance, and persistence of aquatic species in the face of environmental change. Thus, the biological connections established by movement of biota among streams, wetlands, and downstream waters are critical to the ecological integrity of these systems. Future research will help advance our understanding of the movements that link FEMs and their cumulative effects on downstream waters.

Fire-mediated patterns of habitat use by male moose (Alcesalces) in Alaska

Fire severity is an important control over regeneration of deciduous species and can influence the overall quality of habitat for herbivores, such as moose (Alces alces (Linnaeus, 1758)), but the relationships between availability and duration of biomass production and moose habitat use are largely unknown. We evaluate the relative influence of a regenerating burn, paying particular attention to fire severity, on winter forage production and duration, offtake, nutritional quality, and seasonal moose habitat use. We used data from 14 GPS collared male moose in the 20-year-old Hajdukovich Creek Burn (HCB) in interior Alaska, USA, to generate seasonal dynamic Brownian bridge movement models. Within HCB, moose selected for low-severity sites more than high- and moderate-severity sites during the winter. Over the past decade, willow (species of the genus Salix L.) biomass production in low-severity sites has doubled and is likely influencing winter habitat selection patterns. In summer, moose selected for high-severity sites where there is a more abundant understory layer (e.g., stem densities) providing both forage and cover. The initial pulse of biomass production in high-severity sites, as well as the delay in growth and maturation of vegetation in low-severity sites, indicate that differing distributions of wildfire severity can create a dynamic mosaic of habitat patches that may extend the value of burns over time for moose.

Non-Market Food Provision and Sharing in Japan’s Socio-Ecological Production Landscapes

Socio-ecological production landscapes and seascapes (SEPLS) are characterized by a dynamic mosaic of different ecosystem types that maintain relatively high biodiversity and produce a bundle of ecosystem services. One unique characteristic of SEPLS is the sharing of provisioning services within and beyond communities, such as forests, agricultural and marine products. Conventional ecosystem assessments based on statistical data often ignore the benefits of these non-market provisioning services. This short communication quantifies the contribution of the sharing of food provisioning services in Japan in terms of their amount and variety, and it analyzes the relationship between such sharing practices and landscape types. Using an online web survey, we investigated the benefits of sharing goods and services provided from SEPLS. In both mountainous and flat agricultural areas, 16% of the total food amount came from non-market sources, compared to 10% in urbanized areas. Farmland and forests had significant positive correlations with most non-market food items in terms of amount. Greater amounts of built-up area in the landscape were associated with a lesser amount of non-market food provision. Food sharing culture can contribute to enhancing resilience against socio-economic changes and natural disasters. This study provides baseline information for monitoring the hidden flow of food provision and its multiple functions.

Suggested Mechanisms of Tracheal Occlusion Mediated Accelerated Fetal Lung Growth: A Case for Heterogeneous Topological Zones.

In this article, we report an up-to-date summary on tracheal occlusion (TO) as an approach to drive accelerated lung growth and strive to review the different maternal- and fetal-derived local and systemic signals and mechanisms that may play a significant biological role in lung growth and formation of heterogeneous topological zones following TO. Pulmonary hypoplasia is a condition whereby branching morphogenesis and embryonic pulmonary vascular development are globally affected and is classically seen in congenital diaphragmatic hernia. TO is an innovative approach aimed at driving accelerated lung growth in the most severe forms of diaphragmatic hernia and has been shown to result in improved neonatal outcomes. Currently, most research on mechanisms of TO-induced lung growth is focused on mechanical forces and is viewed from the perspective of homogeneous changes within the lung. We suggest that the key principle in understanding changes in fetal lungs after TO is taking into account formation of unique variable topological zones. Following TO, fetal lungs might temporarily look like a dynamically changing topologic mosaic with varying proliferation rates, dissimilar scale of vasculogenesis, diverse patterns of lung tissue damage, variable metabolic landscape, and different structures. The reasons for this dynamic topological mosaic pattern may include distinct degree of increased hydrostatic pressure in different parts of the lung, dissimilar degree of tissue stress/damage and responses to this damage, and incomparable patterns of altered lung zones with variable response to systemic maternal and fetal factors, among others. The local interaction between these factors and their accompanying processes in addition to the potential role of other systemic factors might lead to formation of a common vector of biological response unique to each zone. The study of the interaction between various networks formed after TO (action of mechanical forces, activation of mucosal mast cells, production and secretion of damage-associated molecular pattern substances, low-grade local pulmonary inflammation, and cardiac contraction-induced periodic agitation of lung tissue, among others) will bring us closer to an appreciation of the biological phenomenon of topological heterogeneity within the fetal lungs.

Successional processes in agricultural mosaics in the eastern Amazon

Most tropical landscapes are mainly composed of dynamic mosaics involving multiple land uses. Different histories of land use management can lead to different successional paths. The aim of this study was to determine if there is a successional floristic gradient related to land use types and how these gradients change across three rural mosaics in Eastern Amazon. We also investigated what are the indicator species across mosaics and land use types and how they change through succession. Five sampling points were established in nine family farms at each mosaic. A detrended correspondence analysis was used to reveal the successional gradient. A multivariate regression tree was used to analyze differences in floristic composition between mosaics and land uses. Floristic similarity between land uses formed successional gradient at the mosaics, in which agricultural land uses represent the early stages of secondary succession and forests represent more advanced stages. Total number of species and total number of shade-tolerant species were correlated with advanced successional stages in all mosaics, but pioneer trees were also correlated with advanced stages in fragmented mosaics. Each mosaic had a distinct successional series due to different management approaches. Where the matrix was mainly composed of forest fragments and the human intervention period was shorter, land use types were more similar to one another as they were grouped into fewer successional stages. Thus, the floristic similarity between land use types appears as an indicator of successional advancement across the mosaics and help determine the regenerative capacity of those areas.

Dynamic wetland mosaic environments and Asian openbill habitat creation in peri-urban Bangkok

This study examined the spatial relationships between various types of wetland and the distribution of Asian openbills (Anastomus oscitans) as an indicator species in a peri-urban industrial area of Bangkok. We (1) mapped the study area by using a time series of aerial photographs combined with field validations, (2) conducted a 2-year line census of Asian openbills in the field, (3) interviewed local farmers and residents about Asian openbill populations and spatial distributions, and (4) conducted an overlay analysis to statistically identify land-use factors related to spatiotemporal changes in the Asian openbill population and distribution. We found that the number of ponds increased from 1980 to 1999 and then decreased from 1999 to 2010, but the remaining ponds were relatively temporally stable in their numbers and volumes. Paddy fields were primarily replaced by aquaculture ponds, and excavated soil was used as fill in adjoining built-up areas. The number of coconut, banana, mango and other trees planted around the ponds increased during the period, providing Asian openbill habitat. The openbills fed in the remaining paddy fields, and the simultaneous existence of various rice cultivation stages in the area provided a stable year-round source of food. Overall, the results indicated that this expanding urban–rural mosaic landscape could include further spatial distribution of Asian openbills in the future. This study of Asian openbills reveals just one example of the ecosystem services provided by developments creating pond–fill landscapes, and the methods used may be applicable in other similar continental delta regions.

Long-term Outcomes of Natural-process Riparian Restoration on a Regulated River Site: The Rio Grande Albuquerque Overbank Project after 16 Years

In 1998, a riparian restoration demonstration project was initiated with a target of efficiently establishing a dynamic patch mosaic of vegetation communities along a regulated river using available water and sediment and remaining natural hydrological processes. A point bar along the Middle Rio Grande, Albuquerque, New Mexico, dominated by the non-native shrub Elaeagnus angustifolia (Russian olive), was mechanically treated by removing all vegetation and lowering a portion of the bar to allow overbank flooding during typical spring releases from an upstream dam (Cochiti Dam). Side channels and small islands were engineered in the lowered bar to slow flood waters, aid sediment deposition, and add site complexity. After treatment, a high-resolution monitoring grid was installed to track vegetation changes. Following an initial flood in the spring of 1998, over 10,000 cottonwoods per ha naturally established, but densities varied based on the fluvial landforms. Zones that were sufficiently wetted or naturally formed behind large woody debris were the most successful, while the artificial fill zone and the portion of the bar not lowered had the least native riparian tree recruitment. Over 15 years, cottonwood numbers declined through intraspecific competition and beaver browsing at all sites, but they continued to dominate. Natives also dominated a species-rich herbaceous layer, particularly on the lowered sites. The incursion of a new herbaceous invader, Saccharum ravennae (ravennagrass), was an unexpected outcome revealed by the long-term monitoring record. Yet, based on several criteria, the site reflects a successful application of a natural-process approach to restoration that can lead to increased ecosystem complexity and resilience.

Seasonal rather than spatial variability drives planktonic and benthic bacterial diversity in a microtidal lagoon and the adjacent open sea.

Coastal lagoons are highly productive ecosystems, which are experiencing a variety of human disturbances at increasing frequency. Bacteria are key ecological players within lagoons, yet little is known about the magnitude, patterns and drivers of diversity in these transitional environments. We carried out a seasonal study in the Venice Lagoon (Italy) and the adjacent sea, to simultaneously explore diversity patterns in different domains (pelagic, benthic) and their spatio-temporal variability, and test the role of environmental gradients in structuring assemblages. Community composition differed between lagoon and open sea, and between domains. The dominant phyla varied temporally, with varying trends for the two domains, suggesting different environmental constraints on the assemblages. The percentage of freshwater taxa within the lagoon increased during higher river run-off, pointing at the lagoon as a dynamic mosaic of microbial taxa that generate the metacommunity across the whole hydrological continuum. Seasonality was more important than spatial variability in shaping assemblages. Network analyses indicated more interactions between several genera and environmental variables in the open sea than the lagoon. Our study provides evidences for a temporally dynamic nature of bacterial assemblages in lagoons and suggests that an interplay of seasonally influenced environmental drivers shape assemblages in these vulnerable ecosystems.

Reproductive plasticity and landscape heterogeneity benefit a ground-nesting bird in a fire-prone ecosystem.

Disturbance is critical for the conservation of rangeland ecosystems worldwide and many of these systems are fire dependent. Although it is well established that restoring fire as an ecological process can lead to increased biodiversity in grasslands and shrublands, the underlying mechanisms driving community patterns are poorly understood for fauna in fire-prone landscapes. Much of this uncertainty stems from the paucity of studies that examine the effects of fire at scales relevant to organism life histories. We assessed the response of a non-migratory ground-dwelling bird to disturbance (i.e., prescribed fire) and environmental stochasticity over the course of a 4-yr period, which spanned years of historic drought and record rainfall. Specifically, we investigated the nesting ecology of Northern Bobwhite (Colinus virginianus; hereafter Bobwhite) to illuminate possible avenues by which individuals respond to dynamic landscape patterns during a critical reproductive stage (i.e., nesting) in a mixed-grass shrubland in western Oklahoma, USA. We found that Bobwhites exhibited extreme plasticity in nest substrate use among time since fire categories (TSF) and subsequently maintained high nest survival (e.g., 57-70%). Bobwhites were opportunistic in nest substrate use among TSF categories (i.e., 72% of nest sites in shrubs in 0-12months post fire compared to 71% in herbaceous vegetation in >36months post fire), yet nesting decisions were first filtered by similar structural components (i.e., vertical and horizontal cover) within the vicinity of nest sites regardless of TSF category. Despite being a non-migratory and comparatively less mobile ground-nesting bird species, Bobwhites adjusted to dynamic vegetation mosaics on a fire-prone landscape under stochastic climatic conditions that culminated in stable and high nest survival. Broadly, our findings provide a unique depiction of organism response strategies to fire at scales relevant to a critical life-stage, a topic that has been previously understudied and poorly understood. We also demonstrate how doing so can better inform conservation practices aimed at restoring fire regimes on grassland and shrubland landscapes.

Spatiotemporal heterogeneity of actual and potential respiration in two contrasting floodplains

AbstractFloodplains are vital components of river ecosystems and play an important role in carbon cycling and storage at catchment and global scales. For efficient river management and conservation, it is critical to understand the functional role of spatiotemporally complex and dynamic habitat mosaics of river floodplains. Unfortunately, the fundamental understanding of mineralization and carbon flux patterns across complex floodplains is still fragmentary. In this study, respiratory potential (i.e., electron transport system activity [ETSA]) was quantified seasonally across different aquatic and terrestrial habitats (wetted channels, gravel bars, islands, riparian forests, and grasslands) of 2 Alpine floodplains differing in climate, altitude, discharge, flow alteration intensity, and land use (Soča [natural flow regime, 12% grassland area] and Urbach [mean annual discharge reduction by 30% due to water abstraction, 69% grassland area]). In situ respiration (R) was measured, and ETSA–R ratios were calculated to examine differences in exploitation intensity of the overall respiratory capacity among floodplain habitats and seasons. ETSA and R provided potential and actual estimates, respectively, of organic matter mineralization in the different floodplain habitats. Hierarchical linear regression across habitat types showed that organic matter, grain sizes <0.063 mm, and water content were the most important predictors of ETSA in both floodplains, and grain sizes 2–0.063 and >8 mm were also highly important for the Soča floodplain. The combination of ETSA and R measurements conducted in contrasting floodplains increased our understanding of the relationships between floodplain habitat heterogeneity, organic matter mineralization and human impacts, that is, structural–functional linkages in floodplains. These data are integral towards predicting changes in floodplain function in response to environmental alterations from increasing human pressures and environmental change.

Landscape‐scale interactions of spatial and temporal cropland heterogeneity drive biological control of cereal aphids

Summary Agricultural landscapes are characterised by dynamic crop mosaics changing in composition and configuration over space and time. Although semi‐natural habitat has been often shown to contribute to pest biological control, the effects of increasing landscape heterogeneity with cropland have been disregarded. Here, we examine how cereal aphids, their enemies and biological control are affected by the composition and configuration of the crop mosaic and its inter‐annual change due to crop rotation. We studied the abundance of cereal aphids, natural enemies and aphid parasitism over 2 years on 51 winter wheat fields. Arthropods were monitored at three distances (0, 10, 30 m) from field borders. Fields were embedded in landscapes of 1‐km diameter selected along orthogonal gradients of compositional crop heterogeneity (crop diversity), configurational heterogeneity (field border and grassy field boundary length) and inter‐annual change in cover of aphid host habitats (cereal, maize and grassland). We aimed to disentangle spatial and temporal heterogeneity effects through these independent landscape gradients. Aphid densities were lower in landscapes with smaller field size (more field borders) coupled with high amounts of grassy field boundaries. Aphid densities decreased also in landscapes with higher crop diversity when the cover of aphid host habitat had decreased from the year before. Aphid natural enemy densities decreased with smaller field size and high amounts of grassy field boundaries. Aphid parasitism decreased with the inter‐annual expansion in aphid host habitat, but only in landscapes with small field sizes. Synthesis and applications. Our study shows for the first time that cereal aphid numbers can be reduced by optimising the composition, configuration and temporal heterogeneity of the crop mosaic. We highlight the value of maintaining small field sizes in agricultural landscapes and high densities of grassy boundaries for reducing aphid abundance. Landscape‐wide crop diversification can reduce aphid densities as well.

Late Quaternary Faunal Changes in Northeastern Patagonia (Argentina) according to a Dynamic Mosaic of Benthic Habitats: Taphonomic and Paleoecological Analyses of Mollusk Assemblages

The aim of this study was to describe and interpret the paleoenvironmental history of the San Matias Gulf (SMG) in northern Patagonia, Argentina, associated to possible biotic and abiotic changes occurred during the late Quaternary. In this regard a taphonomic (disarticulation, right/left valve ratio; fragmentation, abrasion, teeth preservation) and paleoecologic (alpha diversity, species abundance, life habit, substrate preference, feeding mode) analysis of A. purputata (the target species) and its accompanying faunal remains (the non-target species) in modern, Holocene and Pleistocene shell assemblages was performed. The general trend of the SMG throughout the late Quaternary is as a low energy environment, with varying intensity depending on the study area. Additionally, each study site contains different substrates showing patches of sand and rock, and this would also have determined the presence of certain species; in turn, the proportion of sandy and rocky patches may have changed over time which led to the development of different local paleocommunities. This gulf therefore presents a dynamic mosaic of environments over time, as evidenced by taphonomic and paleoecological analyses. Its waters would have been sufficiently rich in nutrients to allow the development of the filter fauna which have dominated the late Quaternary, especially A. purpurata. Dual feeder gastropods from hard substrates (Crepidula species) have increased in proportion through the Holocene. The variation in the composition of the fauna accompanying A. purpurata is due to certain physical, biological and even anthropic environmental conditions, which have changed through time. These changes coincided with the Last Glacial Maximum, the final configuration of the SMG and the Climatic Optimum of the Holocene.

Human activities and biodiversity opportunities in pre‐industrial cultural landscapes: relevance to conservation

SummaryConservation practices in Europe frequently attempt to perpetuate or mimic the ‘traditional’ forms of management of semi‐natural habitats, but with a limited understanding of what these entailed.We review the emerging understanding of ecological processes, structures and management interventions that enhance biodiversity (wildlife) at diverse scales. These are then examined in the context of pre‐industrial (c. 1200–1750) land management systems in lowland England, in order to identify historic practices which are likely to have provided important wildlife resources, but which are relatively neglected in current conservation management.Principles enhancing alpha and beta diversity and the conservation status of threatened species include structural complexity and heterogeneity at nested spatial scales; physical disturbance and exposure of mineral substrate; nutrient removal; lengthened successional rotations; and spatial variation in grazing regimes.The available evidence suggests that pre‐industrial land management was generally characterized by intense resource exploitation and significant levels of biomass harvest; complex nested structural heterogeneity both between and within landscape elements; overlaying of multiple land uses; and spatial and temporal variability in management, rendering the concept of long‐lived ‘traditional’ practice problematic. Grazing patterns are poorly understood, but intensive grazing was probably the norm in most contexts, potentially resulting in simplified sward structures and suppressed ecotonal vegetation.In much of the pre‐industrial period, early‐successional and disturbed microhabitats were widespread, but ungrazed or lightly grazed herb‐rich vegetation may have been limited, the converse of current conservation management. The key change since then has been homogenization at multiple scales, coupled with reduction of specific niches and conditions.Synthesis and applications. In adopting perceived ‘traditional’ management practices, modern conservation rarely achieves the range and complexity of conditions that were present in the past. A better understanding of past practices allows more favourable management of those surviving semi‐natural habitats where historic assemblages persist – with greater emphasis on physical disturbance and variability in prescriptions both temporally and spatially. When creating or restoring habitats, after interruption of management sufficiently long for dependent assemblages to be lost, better appreciation of historic management encourages novel forms of intervention to enhance biodiversity, with emphasis on complex structural and spatial heterogeneity at nested scales, biomass removal and nutrient reduction. These strongly management‐based approaches are complementary to the use of large herbivores to create and maintain dynamic ecotonal mosaics in the manner advocated by some proponents of ‘rewilding’.