Increasing Landscape Heterogeneity Research Articles

Crop and landscape heterogeneity increase biodiversity in agricultural landscapes: A global review and meta-analysis.

Agricultural intensification not only increases food production but also drives widespread biodiversity decline. Increasing landscape heterogeneity has been suggested to increase biodiversity across habitats, while increasing crop heterogeneity may support biodiversity within agroecosystems. These spatial heterogeneity effects can be partitioned into compositional (land-cover type diversity) and configurational heterogeneity (land-cover type arrangement), measured either for the crop mosaic or across the landscape for both crops and semi-natural habitats. However, studies have reported mixed responses of biodiversity to increases in these heterogeneity components across taxa and contexts. Our meta-analysis covering 6397 fields across 122 studies conducted in Asia, Europe, North and South America reveals consistently positive effects of crop and landscape heterogeneity, as well as compositional and configurational heterogeneity for plant, invertebrate, vertebrate, pollinator and predator biodiversity. Vertebrates and plants benefit more from landscape heterogeneity, while invertebrates derive similar benefits from both crop and landscape heterogeneity. Pollinators benefit more from configurational heterogeneity, but predators favour compositional heterogeneity. These positive effects are consistent for invertebrates and vertebrates in both tropical/subtropical and temperate agroecosystems, and in annual and perennial cropping systems, and at small to large spatial scales. Our results suggest that promoting increased landscape heterogeneity by diversifying crops and semi-natural habitats, as suggested in the current UN Decade on Ecosystem Restoration, is key for restoring biodiversity in agricultural landscapes.

Euglossini bee diversity is driven by forest cover in coastal Amazon.

Habitat loss and fragmentation are drivers of biodiversity loss, such as Euglossini bees in continental regions. Knowledge about these effects on this group of pollinators in coastal regions is still incipient and needs to be further investigated. This study aimed to evaluate the effects of landscape structure on the abundance, richness, diversity and species composition of Euglossini bees on the coast of the Brazilian Amazon. We mapped the surrounding landscape around 48 sampling points in the east of the island of Marajó, Pará, Brazil where we collected bees using chemical baits. We used Generalized Linear Models (GLMs) to evaluate the effects of landscape structure (composition and configuration) on the abundance, richness, diversity and composition of Euglossini bees. We collected a total of 1017 males belonging to four genera and 22 species. Forest cover (%) and landscape heterogeneity were the best predictors of the bee community. Increased forest cover positively affected the abundance, richness and diversity of bees at a local scale. On the other hand, abundance, richness and diversity decreased with increasing landscape heterogeneity, also at a local scale. The hypothesis that the amount of habitat favors Euglossini communities was corroborated by our results. Based on our conclusions, landscapes with greater forest cover can effectively contribute to the conservation of these bees and their pollination services along the Amazon coast.

Both long-term grasslands and crop diversity are needed to limit pest and weed infestations in agricultural landscapes.

Increasing landscape heterogeneity has been suggested to be an important strategy to strengthen natural pest control in crops, especially through enhancing the amount of seminatural habitats. Increasing crop diversity is also a promising strategy to complement or replace seminatural habitat when seminatural habitat is scarce. However, their relative or possibly interactive effects on pest and weed infestation remain poorly investigated, and the role of different types of seminatural habitats has been understudied. Using an extensive sampling effort in 974 arable fields across 7 y, we evaluated the separate and interactive effects of crop diversity (seven arable crop types) and the amount of four types of seminatural habitats (meadows, hay, forests, and hedgerows) in the landscape on pest and weed control. Meadows and crop diversity, respectively, supported insect pest and weed control services in agricultural landscapes through a complementarity effect. Crop diversity increased weed seed predation rate (by 16%) and reduced weed infestation (by 6%), whereas long-term grasslands (to a much higher degree than hay or woody habitats) increased insect pest predation rates (by 23%) and reduced pest infestation (by 19%) in most arable crops. Our results demonstrate that diversification of the agricultural landscape requires long-term grasslands as well as improved crop diversity to ensure the delivery of efficient pest and weed control services.

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.

Intensity of grassland management and landscape heterogeneity determine species richness of insects in fragmented hay meadows

Traditionally managed grasslands rank among the most species-rich ecosystems. However, in agricultural landscapes of Western and Central Europe, their extent has severely decreased. The remaining patches are mostly fragmented and suffer from habitat deterioration. Here, we studied the effects of environmental conditions on species richness of butterflies and grasshoppers in highly fragmented hay meadows. Our study revealed that environmental parameters at the habitat and landscape level influenced species richness of butterflies and grasshoppers in low-intensity hay meadows. In the univariable models, two groups of parameters consistently affected the number of all and threatened species: at the habitat level, species richness was fostered by structural richness, which was indicative of the overall management intensity of the grassland patches. At the landscape level, a higher number of mowing events in the landscape surrounding the hay meadows had a negative effect and higher elevations exhibiting a cooler and wetter climate had a positive effect on species richness. The former reflected the overall intensity of grassland management in the landscape and the later, together with further predictors (cover of forest, habitat connectivity, slope), the landscape heterogeneity. Consequently, the intensity of grassland management at the habitat and landscape level as well as the landscape heterogeneity, which was also related to land-use intensity, determined species richness of butterflies and grasshoppers. Based on these findings, there is an urgent need to enlarge the proportion of grasslands with low land-use intensity in the wider countryside. Additionally, conservation measures should aim at increasing landscape heterogeneity and habitat connectivity.

Increasing landscape heterogeneity as a win–win solution to manage trade-offs in biological control of crop and woodland pests

Agriculture and forestry cover more than 75% of Europe, and invertebrate pests are a costly challenge for these two economic sectors. Landscape management is increasingly promoted as a solution to enhance biological pest control, but little is known on its effects on adjacent crop fields and woodlands. This study aims to explore the effect of the proportion of woodlands and permanent grasslands as well as crop diversity on biological pest control simultaneously in cereals fields and woodland patches, in south-western France. We used different types of sentinel prey as well as bird and carabid community metrics to assess biological pest control potential in these two ecosystems. We first show that land cover variables influence biological pest control both in cereal fields and woodland patches, but have antagonistic effects in the two ecosystems. Although results vary according to the biological control indicator considered, we show that increasing landscape heterogeneity represents a valuable solution to manage trade-offs and promote higher average predation rates across forests and cereal fields. Our study therefore calls for more integrative studies to identify landscape management strategies that enable nature-based solutions across ecosystems.

Exploring the impact of changing landscape patterns on ecological quality in different cities: A comparative study among three megacities in eastern and western China

The landscape pattern emerges from the intricate interplay among natural, biological, and social elements, profoundly influencing the quality of the regional ecological environment. By comparing the spatial and temporal driving mechanisms of landscape pattern changes on ecological environment quality across various cities, we can gain valuable insights into charting sustainable development paths for cities in the future. The results show that: (1) From 1990 to 2020, the mean RSEI values for Kunming and Nanjing exhibited a certain degree of increase, suggesting an improvement in ecological quality over time. Conversely, Guangzhou displayed relatively high and stable ecological quality throughout the studied period. (2) The CA-Markov results reveal minimal variations in the ecological quality of Kunming by 2035. Conversely, Nanjing experiences a decline in ecological quality, while Guangzhou demonstrates commendable achievements in ecological development, with an area accounting for moderate or higher ecological grades reaching 71.13%. (3) During the 30 years, the polarization of the three cities intensified and gradually formed a polycentric and clustered urban form. Among them, Nanjing and Guangzhou showed a fragmented landscape pattern, while the landscape diversity of Kunming is decreasing. (4) In terms of landscape pattern changes, Nanjing and Guangzhou showed a fragmented landscape pattern and increased landscape heterogeneity, but the degree of fragmentation and the rate of urban expansion in Guangzhou have been mitigated. In contrast, the spatial distribution of landscape patches in Kunming is becoming more clustered and the landscape diversity is decreasing. (5) The results of MGWR show that improving the landscape diversity, landscape patch aggregation and connectivity is beneficial to improving ecological quality. Overall, this study provides valuable insights and serves as a relevant reference for optimizing urban spatial structure in China and other developing countries' cities, aiming to foster sustainable and ecologically conscious urban development.

Landscape heterogeneity and soil biota are central to multi-taxa diversity for oil palm landscape restoration

Enhancing biodiversity in monoculture-dominated landscapes is a key sustainability challenge that requires considering the spatial organization of ecological communities (beta diversity). Here, we tested whether increasing landscape heterogeneity, through establishing 52 tree islands in an oil-palm landscape, is a suitable restoration strategy to enhance the diversity of six taxa (multi-taxa diversity). Further, we elucidated whether patterns in the spatial distribution of above- and below-ground taxa are related, and their role in shaping multi-taxa beta diversity. After five years, islands enhanced diversity at the landscape scale by fostering unique species (turnover). Partial correlation networks revealed that dissimilarity, in vegetation structural complexity and soil conditions, impacts multi-taxa beta diversity and turnover. In addition, soil fauna, bacteria, and fungi were more strongly associated with the overall community than aboveground taxa. Thus, strategies aiming to enhance multi-taxa diversity should consider the central role of landscape heterogeneity and soil biota.

Seasonal shifts in large mammal activity relative to fruit availability and hunting risk along a protected area boundary in Borneo

AbstractUnderstanding wildlife spatiotemporal dynamics at protected area boundaries is critical to conservation. In SE Asia, protected areas are often bordered by indigenous communities whose traditional practices result in increased landscape heterogeneity within their community managed forests (CF). Because SE Asian forests exhibit supra‐annual mast fruiting (3–7 yrs) and sustained fruit scarcity, wildlife using CF may benefit from greater availability of fruits and seeds encouraged by traditional management, but incur greater risk of being hunted. We examined shifts in wildlife activity in forests within and adjacent to Lanjak Entimau Wildlife Sanctuary (LEWS), in Sarawak, Malaysia. Using camera traps and surveys of fruiting phenology, we related presence of fruits and seeds to shifts in large mammal activity over 3 years (October 2016–2019). We first compared relative frequency of five focal species (sun bear, bearded pig, muntjac, mouse deer, and sambar) by forest type for a given survey year and season (rainy vs. dry). We then modeled activity to assess how fruit availability, landscape features, and proxies for hunting risk, influence seasonal shifts in habitat use. Our results suggested seasonal variation in concert with increased landscape heterogeneity influenced patterns of activity. We found no evidence that CF excluded any detected mammal species, suggesting CF contribute important habitat to wildlife, particularly during periods of fruit scarcity in primary forest. However, our findings also imply increased hunting risk for wildlife attracted to resources near human settlements, emphasizing the need to consider the influence of both annual and supra‐annual seasonality when developing best practices for the sustainable management.

No wild bees? Don't worry! Non-bee flower visitors are still hard at work: The edge effect, landscape, and local characteristics determine taxonomic and functional diversity in apple orchards

Native pollinators are key to enhancing fruit production in apple orchards and maintaining yield stability through taxonomic and functional diversity. Some studies suggest that the distance to the nearest native forest patch, the edge effect, or apple orchard management, modulate the richness and abundance of pollinators. However, such studies have focused on bees, thereby generating knowledge gaps about non-bee pollinators. This study looks at the taxonomic and functional diversity in central Chile, as well as the abundance of major pollinator groups (native beetles, flies, wild bees, and lepidopterans), and how these are influenced by landscape and apple orchard characteristics. For two seasons, native and managed pollinators were recorded in nine apple orchards with different management approaches (organic vs conventional) and apple varieties (Gala vs Fuji). The taxonomic and functional diversity of major pollinator groups were correlated with distance to the nearest native forest patch. We measured the edge effect on pollinators toward the interior of apple orchards and analyzed the results with one-way ANOVA. Lastly, we associated the diversity and abundance of pollinators with landscape and apple orchards characteristics using GLMM. Excepted managed bees and contrary to the global trend in apple studies, native flies and beetles were the most dominant pollinators, the latter being more abundant at the orchard edge. The distance to the native forest patch was correlated negatively to the functional richness and positively to body temperature, while that same variable influenced the abundance of total native pollinators, beetles, flies, and wild bees. The gala variety was found to attract greater pollinator richness and more wild bees, whereas organic orchards positively influence native flies and conventional orchards attract lepidopterans. Moreover, the number of honey bees influences the abundance of wild bees and lepidopterans. Land intensification practices could decrease the taxonomic and functional diversity of pollinators. Management alternatives like increased landscape heterogeneity or native habitat restoration, could to maintain apple fruit production in space and time.

City-Region Food Systems and Biodiversity Conservation: The Case Study of the Entre-Douro-e-Minho Agrarian Region

Agriculture is the dominant form of land management with at least half of the species in Europe depending on agricultural habitats. Additionally, there is a growing demand for a more sustainable food system. In that context, food system relocalization and City-Region Food Systems (CRFS) are proposed for food resilience and environmental sustainability. This work represents the first attempt to map the relocalization of the potential foodshed (PF) of the Entre-Douro-e-Minho agrarian region, assessing its impacts on landscape heterogeneity and ecological value. The methodological approach, developed in a Geographic Information System, aimed to (1) map the ecological suitability of the study area, (2) propose a PF relocalization scenario, and (3) assess its impacts on land cover changes and landscape structure through landscape metrics. Outcomes of this research reflect land-use optimization concerning ecological suitability for agrarian uses, depicting the strong presence of temporary crops in the landscape. They also emphasize the need for greater detail in Land Use Plans, due to the vulnerability of coastal areas. Moreover, results revealed an increased landscape heterogeneity and related ecological value, highlighting the integration of landscape ecological properties into CRFS planning as a line of research and contributing to the implementation of land use compatible with biodiversity conservation.

Mountains and their ecotones increase landscape heterogeneity and maintain a unique assemblage of grasshoppers in the southern Kalahari

Abstract South Africa is a megadiverse country. Here, natural communities are unevenly distributed across, and within, seven distinct biomes. In such heterogeneous landscapes, understanding spatial patterns of biodiversity is essential for planning and implementing efficient conservation measures. The southern Kalahari, forming part of South Africa's savanna biome, is an arid region of peculiarly high diversity and endemism. The responses of orthopteran assemblages to changing environmental conditions across the Kalahari were investigated by comparing alpha and beta diversity levels across discrete vegetation types in the Tswalu Kalahari Reserve. The degree of association between species and specific vegetation types were also studied and how a key life history trait ‐ dispersal ability – influences community composition was determined. This study identified 46 grasshopper species within the reserve, which compares well with richness levels in other more productive habitats of the country. Local (alpha) diversity was higher in mountain and mountain‐ecotone sites versus vegetation types on the plains, and species turnover was also exceptionally high – approaching 100% ‐ across these two groups. The few (3) dispersal limited species recovered were associated only with the mountain‐ecotone group, with emergent dominance patterns suggesting that competitive rather than dispersal abilities determine the species composition of unique assemblages in the landscape. Topology plays a key role in maintaining spatial diversity across the southern Kalahari landscape. Mountains, and their ecotones, promote not only species turnover, but also richness and functional diversity. These can be viewed as islands of diversity, and should be targeted priority areas for conservation beyond the boundaries of protected areas.

Evolution and Influencing Factors of Landscape Pattern in the Yellow River Basin (Henan Section) Due to Land Use Changes

The temporal and spatial evolution of landscape pattern is the most intuitive form of land use transition. Analyzing the change of landscape pattern and its driving factors is of great significance to land use management and water quality protection in the basin. Based on the land use data obtained from the remote sensing image interpretation of the Yellow River Basin (Henan section) in 1990, 2000, 2010, and 2020, the landscape pattern evolution characteristics of the Yellow River Basin (Henan section) were quantitatively studied using the methods of multi-angle land use transfer matrix, land use information atlas, and landscape pattern index, and the influencing factors of landscape pattern evolution of the Yellow River Basin (Henan section) were revealed using the geographic detectors (a new statistical method to measure the explanatory power of independent variables to dependent variables mainly by analyzing the overall differences among various types of geographical spaces). The results show that: (1) From 1990 to 2020, the mutual transformation of land use types in the Yellow River Basin (Henan section) was frequent, and the transformation tracks were diversified. Among them, the outflow behavior of land use types is mainly manifested in the transformation from cultivated land to construction land, and the inflow behavior of land use types is mainly manifested in the transformation from grassland and water to cultivated land. (2) In the information map of land use change in the Yellow River Basin (Henan section) from 1990 to 2020, the stable type had the widest distribution range, accounting for 94.60% of the total area of the study area, with two main change patterns: “cultivated land-cultivated land-cultivated land-cultivated land” and “woodland-woodland-woodland-woodland”, which indicates that the landscape pattern of the basin dominated by cultivated land and woodland has not changed fundamentally. The four land use change structure types, repeated change, early change, intermediate change and continuous change, account for a relatively small proportion and are concentrated in the vicinity of the Yellow River. (3) At the landscape level, the watershed generally shows the trend of decreasing landscape fragmentation, increasing landscape heterogeneity and constantly balancing landscape patch types. At the level of patch type, the landscape dominance of cultivated land decreases, while that of construction land increases. The occupation of construction land is the main reason for the fragmentation and homogenization of cultivated land. (4) From the perspective of landscape scale and patch type scale, through the geographical exploration of various natural factors and socio-economic factors that potentially affect the landscape pattern evolution, it is found that the spatial differences of natural factors such as slope, elevation, temperature, and precipitation can better reflect the spatial heterogeneity of the landscape pattern in the Yellow River Basin (Henan section) than those of socio-economic factors such as GDP and population density, and the interaction of any two driving factors has a greater influence on the spatial distribution characteristics of landscape pattern than any single factor, indicating that the formation of spatial heterogeneity in the Yellow River Basin (Henan section) is the result of the interaction of various influencing factors. The results of this study can provide ideas for exploring the trend and influencing mechanism of landscape pattern change in the basin, and have important reference significance for ecological environment management, ecosystem protection, and land use planning in the Yellow River Basin (Henan section).

The effects of external forcing agents on the biodiversity and species richness associated with the environmental history of Louisiana's wetlands over the late Holocene

This study evaluates plant diversity and species richness levels and reconstructs the environmental history of a site near Little Lake in southeast Louisiana, USA over the past 3200 years. Six successive ecosystems occurred as a result of changing environmental conditions, ranging from the local (anthropogenic activities), regional (delta lobe switching), and to global (sea level rise): interdistributary bay (3.2–2.3 cal kyr BP), hydrophytic freshwater marsh (2.3–1.42 cal kyr BP), mesophyte coastal prairie (1.42–0.92 cal kyr BP), Typha marsh (0.92–0.33 cal kyr BP), intermediate marsh (0.33 cal kyr Bp – ad, 1972 CE), brackish marsh (197 CE2-present). Biodiversity was evaluated for each ecosystem, with maximum diversity occurring during the period of maximum delta-growth as the river dynamics increased landscape heterogeneity by creating diverse habitats, including marsh, swamps, oxbow lakes, and natural levees, while the transgressive phase presents the lowest biodiversity due to increasing salinity. Multivariate analysis is used to identify the primary depositional processes for each stage and infer the proximate forcing agents(s). Early ecosystem shifts were controlled by the stages of the delta cycle, while more recent shifts are associated with anthropogenic activities and the effects of global climate change such as sea-level rise, and more intense tropical cyclones.

Humid grassland fallows promote spider diversity in a traditionally managed landscape

Agricultural intensification is an important driver of biodiversity decline. Regarding grassland ecosystems, traditionally managed hay meadows, as opposed to highly productive silage grassland, are often of high conservation value. Here, we compare spider assemblages among five grassland management regimes along an intensification gradient, ranging from long-term fallows (not farmed for ≥ 30 years) via traditionally managed hay meadows to high-intensity silage grassland. Humid long-term fallows harboured highest species richness and diversity, and their assemblages differed strongly from other management regimes. There was surprisingly little variation though among different types of hay meadows and silage grassland. We also included environmental parameters and land-cover types in the surroundings of study sites, indicating that spider assemblages were most strongly shaped by fallow-related parameters and the proportion of forests. The high spider diversity on fallows may result from their undisturbed vegetation structure, while management, regardless of frequency, may have detrimental effects. Our results demonstrate the high importance of unmanaged areas even in regions with an overall low land-use intensity, such as grassland ecosystems. We thus recommend the inclusion of temporal grassland fallows (unmanaged for 3-5 years) in agri-environmental schemes to increase landscape heterogeneity and preserve spider diversity.

Effects of ungulate density and sociality on landscape heterogeneity: a mechanistic modeling approach

Animals can be important vectors of nutrient transfer within and across landscapes, with important implications for ecosystem productivity and composition. While it is presumed large ungulates are agents of nutrient dispersal via movement and activity, research analyzing their net effects on landscapes remains scarce. We present an individual‐based model that investigates how caribou affect the distribution of nutrients on a landscape through consumption only, as well through the cumulative effects of consumption and nutrient deposition (i.e. fecal waste and carcass deposition). We explored these dynamics in simulations that altered the context of environments, either initially containing heterogeneous or homogeneous nutrient distributions, animal densities and sociality of caribou behavior. In the consumption‐only simulations, caribou density and sociality created different patterns of heterogeneity at both the landscape and local scale depending on the initial landscape conditions. In these simulations, caribou populations crashed at high densities because the lack of animal deposition resulted in low resources across the landscape. This was not the case when considering the cumulative effects of consumption and deposition, indicating the return of nutrients from animals may be important for population stability. Additionally, in simulations considering the cumulative effects of caribou, increasing caribou density increased landscape heterogeneity irrespective of the initial condition (i.e. heterogeneous and homogeneous landscapes), and maintained or increased local heterogeneity in heterogeneous and homogenous landscape, respectively. Importantly, in all simulations the net impact of caribou at the individual patch level was extremely variable, suggesting that animal inputs are highly varied throughout the landscape. Our results indicate the movement of large ungulates such as caribou can increase the heterogeneity of available nutrients within a landscape and provide an important feedback for population stability. Thus, the loss of large ungulates from natural ecosystems via anthropogenic activity is likely to result in less heterogeneous natural landscapes.

Low- and moderate-severity fire offers key insights for landscape restoration in ponderosa pine forests.

Restoration goals in fire-prone conifer forests include mitigating fire hazard while restoring forest structural components linked to disturbance resilience and ecological function. Restoration of overstory spatial pattern in forests often falls short of management objectives due to complexities in implementation, regulation, and available data. When historical data is available, it is often collected at plots too small to inform coarse-scale metrics like gap size and structure of tree patches (e.g., 1 ha). Principles of ecological forestry typically emphasize overstory removal patterns that emulate those of natural disturbances. So, low- and moderate-severity portions of contemporary wildfires may serve as a guide to restoration treatments where mixed-severity fires occur. Here, we compare forest spatial pattern and configuration in 15 mechanical restoration treatments and low- and moderate-severity portions of three wildfires in ponderosa pine-dominated forests to determine how they differ in spatial pattern. We obtained satellite imagery of restoration treatments and wildfires and used supervised classification to differentiate canopy and openings. We assessed elements of landscape structure including canopy and gap cover, gap attributes, and landscape heterogeneity for each disturbance type. We found that both mechanical restoration treatments and low- and moderate-severity portions of wildfires reduced forest cover, increased gap cover, and altered pattern and arrangement of gaps relative to undisturbed areas, though the magnitude of changes were greatest in the burned sites. Low- and moderate-severity wildfire consistently increased landscape heterogeneity, but mechanical treatments did not. This suggests that a greater emphasis on increasing gap and patch spatial structure may make mechanical treatments more congruent with natural disturbances. Outcomes of low- and moderate-severity portions of wildfires may provide important information upon which to base management prescriptions where reference data on landscape patterns is unavailable.

Grassland fallows as key for successful insect conservation

Abstract There is widescale evidence for declines in insect biodiversity at a global scale. Agricultural intensification is considered to be one of the major causes of these declines. Traditionally managed habitat types, such as hay meadows, harbour a rich diversity of plants and animals but have been often transformed into crop fields or silage grassland. To evaluate the role of (i) agricultural intensification for insect declines and of (ii) traditionally managed hay meadows and fallows for biodiversity conservation, we here compare bee, hoverfly, and leafhopper assemblages on 45 sites along a gradient of land use intensity in western Germany. We included moist long‐term grassland fallows, three types of hay meadows, and silage grasslands, each represented by nine replicates. Species numbers of bees and leafhoppers were significantly higher on fallows than other management types. Grassland fallows also harboured the most distinct assemblages, while those of hay meadows and silage grassland were very similar and largely overlapping. The surprising similarity of hay meadow and silage assemblages may be due to investigating highly mobile taxa within a landscape composed of a fine‐scale mosaic of traditionally managed and intensified grassland. Our results demonstrate the high importance of unmanaged areas, even when the overall land use intensity is still comparatively low. We suggest that temporal grassland fallows (unmanaged for 3–5 years) should be subsidised in agri‐environmental schemes to increase landscape heterogeneity and to preserve insect diversity.

Time matters: Resilience of a post-disturbance forest landscape

Present-day disturbances are transforming European forest landscapes, and their legacies determine the vulnerability and resilience of the emergent forest generation. To understand these legacy effects, we investigated the resilience of the aboveground forest biomass (Babg) to a sequence of disturbances affecting the forest in different recovery phases from the initial large-scale impact. We used the model iLand to simulate windthrows that affected 13–24% of the Babg in a Central European forest landscape. An additional wind event was simulated 20, 40, 60, or 80 years after the initial impact (i.e., sequences of two windthrows were defined). Each windthrow triggered an outbreak of bark beetles that interacted with the recovery processes. We evaluated the resistance of the Babg to and recovery after the impact. Random Forest models were used to identify factors influencing resilience. We found that Babg resistance was the lowest 20 years after the initial impact when the increased proportion of emergent wind-exposed forest edges prevailed the disturbance-dampening effect of reduced biomass levels and increased landscape heterogeneity. This forest had a remarkably high recovery rate and reached the pre-disturbance Babg within 28 years. The forest exhibited a higher resistance and a slower recovery rate in the more advanced recovery phases, reaching the pre-disturbance Babg within 60–80 years. The recovery was enhanced by higher levels of alpha and beta diversity. Under elevated air temperature, the bark beetle outbreak triggered by windthrow delayed the recovery. However, the positive effect of increased temperature on forest productivity caused the recovery rate to be higher under the warming scenario than under the reference climate.We conclude that resilience is not a static property, but its magnitude and drivers vary in time, depending on vegetation feedbacks, interactions between disturbances, and climate. Understanding these mechanisms is an essential step towards the operationalization of resilience-oriented stewardship.

Linking pollinator occurrence in field margins to pollinator visitation to a mass-flowering crop

Uncultivated field margins are important refugia for pollinating insects in agricultural landscapes. However, the spill-over of pollination services from field margins to adjacent crops is poorly understood. This study (i) examined the effects of landscape heterogeneity on pollinator occurrence in permanent field margins and pollinator visitation to adjacent mass-flowering turnip rape (Brassica rapa ssp. oleifera) in boreal agricultural landscapes, and (ii) tested whether pollinator abundance and species richness in field margins predict abundance and species richness of crop visitors. Pollinators visiting the crop were more affected by landscape heterogeneity than pollinators in adjacent margins. Species richness, total abundance, and the abundance of syrphid flies visiting the crop increased with increasing landscape heterogeneity, whereas, in field margins, landscape heterogeneity had little effect on pollinators. In field-dominated homogeneous landscapes, wild pollinators rarely visited the crop even if they occurred in adjacent margins, whereas in heterogeneous landscapes, differences between the two habitats were smaller. Total pollinator abundance and species richness in field margins were poor predictors of pollinator visitation to adjacent crop. However, high abundances of honeybees and bumblebees in margins were related to high numbers of crop visitors from these taxa. Our results suggest that, while uncultivated field margins help pollinators persist in boreal agricultural landscapes, they do not always result in enhanced pollinator visitation to the adjacent crop. More studies quantifying pollination service delivery from semi-natural habitats to crops in different landscape settings will help develop management approaches to support crop pollination.