Functional landscape heterogeneity and animal biodiversity in agricultural landscapes

ABSTRACTThe influence of crop and landscape heterogeneity on different components of biodiversity in agricultural landscapes has been assessed at multiple scales. However, how crop species diversity relates to landscape heterogeneity remains underexplored at the global scale. We apply independent global spatial datasets to test the relationship between crop and landscape heterogeneity across 19,505 agricultural landscapes worldwide. We first examine the spatial patterns in crop diversity and landscape diversity (compositional heterogeneity), defined as the effective number of crop species and land cover types, respectively, based on Shannon entropy. Median crop diversity increases on average by 0.36–0.48 effective species for each unit increase in land cover diversity globally. We use quantile generalized additive models (QGAM) to statistically test this relationship. The QGAM approach confirms that crop diversity has a positive but complex relationship with landscape diversity, particularly for landscapes with ≥ 4–5 non‐crop cover types. However, this positive trend is context‐dependent, as the clearest median response generally corresponds to landscapes with moderate cropland extents (25%–75% cropland). We also examine how other components of landscape compositional and configurational heterogeneity, including dominant agricultural field size and patch size, as well as topographic heterogeneity are associated with crop diversity. The relatively highest crop diversity tends to correspond to very small dominant agricultural field sizes (crop configurational heterogeneity) when controlling for cropland extent and non‐agricultural land cover diversity. Mean patch area (landscape configurational heterogeneity) has a strong negative association with crop diversity until patch sizes of > 150 km2 while topographic heterogeneity has a consistent positive association with crop diversity. Our findings therefore demonstrate how the diversity of non‐agricultural land covers in conjunction with configurational heterogeneity has relevance to understanding existing patterns of spatial crop diversity. Such insights could help inform efforts to design more multifunctional agricultural landscapes, including landscape‐scale farm diversification strategies.

Conserving biodiversity, especially in agricultural landscapes, is a major societal challenge. Broad scientific evidence exists on the impacts of single drivers on biodiversity, such as the intensification of agriculture. However, halting biodiversity decline requires a systemic understanding of the interactions between multiple drivers, which has hardly been achieved so far. Selecting Germany as a case study, the goal of our analysis is (i) to understand how various socio‐economic drivers of biodiversity in agricultural landscapes interact at the national scale, (ii) to identify plausible pathways that most likely will lead to an improvement of biodiversity in agricultural landscapes and (iii) to discuss guiding principles for policy‐making based on the pathways. We applied the expert‐based Cross‐Impact‐Balance (CIB) methodology to the German agri‐food system (target year 2030). Seven descriptors that represent the most relevant socio‐economic drivers of biodiversity (here, we focus on species richness) in agricultural landscapes in Germany were defined. In three workshops with different groups of experts, we assessed all the interactions and impacts between these descriptors. From the workshops, seven overlapping scenarios were identified and aggregated into four main future pathways for enhancing biodiversity in agricultural landscapes. These pathways are: (1) ‘Innovation and stricter legislation’, (2) ‘Major change in protein production and CAP shift’, (3) ‘Major change in protein production and national legislation’ and (4) ‘Major social changes compensate for a lack of innovation in food production’. Socio‐economic drivers interact to varying degrees. Societal values have a strong active influence on the system, e. g. agricultural policy, whereas the orientation and objectives of agriculture, e. g. focus on public goods, are rather passively determined. Conserving biodiversity thus depends upon the evolution of societal values, European and national nature conservation and agricultural policies, innovations in plant and protein production as well as on global commodity markets. A key message for policymakers is that there are generally different, complementary options for achieving the objective of improving biodiversity. This is important when specific drivers such as the CAP cannot be steered in a particular desired direction. Read the free Plain Language Summary for this article on the Journal blog.

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.

Although homegardens are most often suggested as the refuges for biodiversity in human-dominated landscapes, how the surrounding landscape and socioeconomic characteristics affect this diversity in the tropics has received little research attention. Hence, this study has examined how these factors affect woody species diversity in homegardens of northeast Ethiopia. Three landscapes which are similar in agroecology were selected and in total 54 households were used for both a survey and a woody species inventory in respondents’ homegardens. The homegardens were stratified based on their locations in relation to crop fields and natural vegetation using satellite images from Google Earth. The variation in Shannon–Wiener diversity index among homegardens and the effect of the socioeconomic factors including household wealth status, homegarden area and the households’ types of uses of woody plants on species diversity were analyzed using one-way ANOVA. Altogether 53 woody plant species belonging to 35 botanical families were identified. Survey results indicated that the woody species diversity was higher in homegardens situated close to crop land as compared with the diversity in homegardens close to natural vegetation. Higher woody species diversity was recorded in homegardens which are larger in area and where the households’ types of uses of woody plants is higher. Moreover, the woody species diversity was found to be higher in homegardens of the high and medium income households when compared with that of poor households. Overall, results suggest that the concurrent ecological and socioeconomic studies are needed to design conservation strategy and policy for plant biodiversity in agricultural landscapes.

Summary Landscape heterogeneity represents two aspects of landscape simplification: (i) compositional heterogeneity (diversity of habitat types); and (ii) configurational heterogeneity (number, size and arrangement of habitat patches), both with different ecological implications for community composition. We examined how independent gradients of compositional and configurational landscape heterogeneity, at eight spatial scales, shape taxonomic and functional composition of butterfly communities in 91 managed grasslands across Germany. We used landscape metrics that were calculated from functional maps based on habitat preferences of individual species during different life stages. The relative effects of compositional and configurational landscape heterogeneity were compared with those of local land‐use intensity on butterfly taxonomic diversity, community composition and functional diversity of traits related to body size, feeding breadth and migratory tendency. As expected, compositional heterogeneity had strong positive effects on taxonomic diversity, while configurational heterogeneity had strong positive effects on trait dominance within the community. When landscapes had smaller mean patch size and greater boundary area, communities were dominated by species with more specialized larval feeding, decreased forewing length and limited migratory tendency. The positive effects of increased configurational landscape heterogeneity outweighed the negative effects of local land‐use intensity on larval‐feeding specialization, at all spatial scales, highlighting its importance for specialists of all dispersal capabilities. Synthesis and applications. We show that landscapes with high compositional heterogeneity support communities with greater taxonomic diversity, while landscapes with high configurational heterogeneity support communities that include vulnerable species (feeding specialists with larger body size, sedentary nature and more negatively affected by local management intensity). A decline in functional community composition can lead to functional homogenization, affecting the viability of the ecosystems by decreasing the variability in their responses to disturbance and altering their functioning. A landscape management for grasslands that promotes the maintenance of small patch sizes and a diversity of land uses in the surrounding landscape (within 250–1000 m) is recommended for the conservation of diverse butterfly communities. These strategies could also benefit government programmes such as the EU 2020 Biodiversity Strategy in their efforts to reduce the loss of biodiversity in agricultural landscapes.

Connectivity of cropped vs. semi-natural habitats mediates biodiversity: A case study of carabid beetles communities

The dominant late twentieth century model of land use segregated agricultural production from areas managed for biodiversity conservation. This module is no longer adequate in much of the world. The Millennium Ecosystem Assessment confirmed that agriculture has dramatically increased its ecological footprint. Rural communities depend on key components of biodiversity and ecosystem services that are found in non-domestic habitats. Fortunately, agricultural landscapes can be designed and managed to host wild biodiversity of many types, with neutral or even positive effects on agricultural production and livelihoods. Innovative practitioners, scientists and indigenous land managers are adapting, designing and managing diverse types of 'ecoagriculture' landscapes to generate positive co-benefits for production, biodiversity and local people. We assess the potentials and limitations for successful conservation of biodiversity in productive agricultural landscapes, the feasibility of making such approaches financially viable, and the organizational, governance and policy frameworks needed to enable ecoagriculture planning and implementation at a globally significant scale. We conclude that effectively conserving wild biodiversity in agricultural landscapes will require increased research, policy coordination and strategic support to agricultural communities and conservationists.

Digital and smart technologies (DSTs1) for agriculture are currently widely discussed in the literature and increasingly included in common farming practices. However, the main agricultural use of DSTs remains yield-increasing and effort-reducing applications focused on the economic advantages of precision. The potential of DSTs to enhance biodiversity in agricultural landscapes has rarely been examined, especially from the stakeholder perspective. In this study, we examined the barriers to and potential for using DSTs to promote biodiversity in agricultural areas in Germany. For this purpose, we conducted a nationwide stakeholder acceptance analysis based on an online survey and an expert discussion. Our analysis revealed the notable potential of DSTs to strengthen biodiversity in agricultural landscapes, which is, however, accompanied by critical barriers to the broad acceptance and regular use of such technologies by farmers. Only if based on adequate legal and financial political framework, which create incentives for solution-focused cooperation among all relevant stakeholders and allow a user-orientated technology development, can DSTs develop their underlying potential and gain acceptance among farmers.

Configurational landscape heterogeneity: Crop-fallow boundaries enhance the taxonomic diversity of carabid beetles and spiders

Agriculture is associated with many of the leading threats to freshwater ecosystems, which are the most threatened environments on Earth. The overarching goal of my dissertation was to advance our understanding of the relationships between agricultural landscape structure and aquatic biodiversity and water quality, to identify potential management options for farmland aquatic ecosystems. In Chapter 2, I investigated the responses of anurans to agricultural landscape structure, with the particular goal of testing predictions about the influence of farmland compositional and configurational heterogeneity. I found that, while forest cover was the strongest predictor of anuran richness and abundance, farmland configurational heterogeneity was also positively related to abundance. In Chapter 3, I investigated the direct and indirect relationships between agricultural landscape structure and different physicochemical and biological measures of water quality in farmland drainage ditches. I found that physicochemical water quality was most strongly related to landscape composition, specifically, amounts of forest cover and high-intensity crop cover in the surrounding landscape. I also found support for a positive direct relationship between a biological measure of water quality, macroinvertebrate richness, and configurational heterogeneity, and indirect relationships between macroinvertebrate richness and landscape composition. In Chapter 4, I examined whether macroinvertebrate traits can be used as reliable indicators of elevated levels of specific agrichemical pollutants in farmland drainage ditches. My results suggested that macroinvertebrate indicators are probably less efficient than rigorous chemical sampling for the monitoring of specific contaminants in farm wetlands. Taken together, my results suggest that landscape management to support farmland aquatic ecosystems should focus mainly on landscape composition; in particular, agri-environmental policies should aim to increase or maintain amounts of non-crop cover such as forest, and reduce or maintain low amounts of high-intensity crop cover. My results also suggest that increasing farmland configurational heterogeneity, through reducing crop field sizes/increasing edge density, can be an effective management option to enhance aquatic biodiversity in agricultural landscapes. In addition, my results indicate a need for more management actions in our region to reduce nutrient pollution, and stronger policies for routine water quality data collection, as well as establishment and enforcement of water quality standards.

Semi‐natural habitats are considered as the main source of biodiversity in agricultural landscapes. Most landscape ecology research has focused on the amount (relative surface) and spatial organisation of these habitats. However, these two components of landscape heterogeneity, composition and configuration, are often correlated. Also, landscape structure effects on biodiversity were mostly observed locally, while there is a great need for studying landscape‐scale gamma diversity. We conducted a mensurative experiment to determine the independent effects of semi‐natural habitat amount and configuration on gamma diversity of carabid beetles and vascular plants. The influence of landscape heterogeneity components were tested on species richness, evenness and composition. Local diversity (species richness and composition) was compared across the various cover types to determine their relative contributions. Only carabid species evenness and composition were influenced by semi‐natural habitat amount. Carabid and plant species richness and plant species composition remained unaffected by semi‐natural habitats. Local diversity analysis showed that three types of habitats can be distinguished in agricultural landscapes: grasslands (temporary and permanent ones), woody habitats (woodlands and hedgerows) and row crops. These results beg for a re‐evaluation of the semi‐natural covers. Temporary and permanent grasslands are often similar, probably because of comparable farming management. Permanent grasslands and woody habitats are often combined as semi‐natural covers, although they support very different communities. The lack of effect of semi‐natural habitat amount and configuration on gamma diversity results from a more complex organisation of biodiversity in landscapes and supports the move from semi‐natural vs. farmland to habitat mosaic landscape representations.

The 'European Monitoring of Biodiversity in Agricultural Landscapes' (EMBAL) is a monitoring initiative initiated by the European Commission that gathers information on the state of biodiversity in agricultural landscapes across EU member states. Developed within the EU Pollinator Monitoring Framework, EMBAL is a standardized and sample-based in-situ survey of 500x500m landscape sections (plots). EMBAL provides comprehensive data, including general information on land use and land cover at parcel level, information about landscape elements, and specific vegetation data on a transect level in grassland and arable habitats. Both the methodology and the sampling frame are harmonized with LUCAS (Land Use and Coverage Area frame Survey). Following a successful pilot in 2020, EMBAL was applied in all 27 EU member states in 2022 and 2023, surveying a total of 3,000 selected plots in both years. This extensive rollout served to gather harmonised baseline data on biodiversity across EU27 and provided a comprehensive field test of the EMBAL methodology across different European landscapes. In this contribution, we offer an overview of the EMBAL 2022 and 2023 rollout, the EMBAL survey methods and parameters and provide an outlook on the results.

Summary In many European agricultural landscapes, species richness is declining considerably. Studies performed at a very large spatial scale are helpful in understanding the reasons for this decline and as a basis for guiding policy. In a unique, large‐scale study of 25 agricultural landscapes in seven European countries, we investigated relationships between species richness in several taxa, and the links between biodiversity and landscape structure and management. We estimated the total species richness of vascular plants, birds and five arthropod groups in each 16‐km2 landscape, and recorded various measures of both landscape structure and intensity of agricultural land use. We studied correlations between taxonomic groups and the effects of landscape and land‐use parameters on the number of species in different taxonomic groups. Our statistical approach also accounted for regional variation in species richness unrelated to landscape or land‐use factors. The results reveal strong geographical trends in species richness in all taxonomic groups. No single species group emerged as a good predictor of all other species groups. Species richness of all groups increased with the area of semi‐natural habitats in the landscape. Species richness of birds and vascular plants was negatively associated with fertilizer use. Synthesis and applications. We conclude that indicator taxa are unlikely to provide an effective means of predicting biodiversity at a large spatial scale, especially where there is large biogeographical variation in species richness. However, a small list of landscape and land‐use parameters can be used in agricultural landscapes to infer large‐scale patterns of species richness. Our results suggest that to halt the loss of biodiversity in these landscapes, it is important to preserve and, if possible, increase the area of semi‐natural habitat.

Agricultural land comprises an important share of the total terrestrial land. Therefore it plays a crucial role in the health of the so-called foundation of all types of ecosystem services – biodiversity. This research aims at providing a tool for evaluating the state of biodiversity in an agricultural landscape by using different agri-environmental indicators. A system dynamics model is built that encloses agricultural land use parameters, agricultural land use intensity, landscape fragmentation patterns, crop diversity and other aspects that have an important effect on biodiversity in agricultural landscapes. This research is an attempt to use information available for public to assess the degree to which agricultural landscape may benefit from landscape greening activities, changes in crop management activities etc. At the end of this research landscape biodiversity of an intensive farming region in Latvia (Bauska district) will be evaluated.

Amphibians play a key role in structuring biological assemblages of agricultural landscapes, but they are threatened by global agricultural intensification. Landscape structure is an important variable influencing biodiversity in agricultural landscapes. However, in the Yangtze River Delta, where a "farmland-orchard-fishpond" agricultural pattern is common, the effects of landscape construction on anuran populations are unclear. In this study, we examined the effects of agricultural landscape parameters on the abundance and body condition of the rice frog (Fejervarya multistriata), which is a dominant anuran species in farmland in China. Employing a visual encounter method, we surveyed rice frog abundance for 3 years across 20 agricultural landscapes. We also calculated the body condition index (BCI) of 188 male frog individuals from these agricultural landscapes. Landscape variables, comprising landscape compositional heterogeneity (using the Shannon diversity index of all land cover types except buildings and roads), landscape configurational heterogeneity (using landscape edge density), breeding habitat diversity (using the number of 5 waterbody types available as breeding habitats), and areas of forest were also measured for each 1-km radius landscape. We found that the amount of forest in each agricultural landscape had a significant positive relationship with rice frog abundance, and breeding habitat diversity was positively related to the BCI of male rice frogs. However, body condition was negatively impacted by landscape configurational heterogeneity. Our results suggested the importance of nonagricultural habitats in agricultural landscapes, such as waterbodies and forest, to benefit rice frog population persistence.