Heterogeneous Agricultural Landscapes Research Articles

Structural complexity of arthropod guilds is affected by the agricultural landscape heterogeneity generated by fencerows

Intensive farming imposes harsh conditions impeding the persistence of most arthropod species within crop fields. Hence, arthropods surviving the unfavourable conditions prevailing within crop fields may disperse towards nearby uncropped margins, such as fencerows. Here, we evaluate the influence of landscape heterogeneity on the abundance of different guilds, particularly herbivores and their natural enemies. Said heterogeneity mostly derives from fencerow network density. Hence, we developed an approach based on fitting linear-mixed models to elucidate the effects of landscape heterogeneity and field position (fencerows and crop interiors) on arthropod diversity. Mixed models were fitted to arthropod data obtained by pitfall trap samplings in 36 crop fields. Arthropod communities were structurally and functionally more complex along fencerows than within nearby crop interiors. Arthropods abundance was modulated by landscape heterogeneity, increasing the abundance of natural enemies as the landscape heterogeneity increased. On the contrary, herbivores abundance decreased as landscape heterogeneity increased. Consequently, the ratio between herbivores and natural enemies also decreased as landscapes became more heterogeneous. Natural enemies with larger body sizes, mostly carabid beetles, were more sensitive to landscape homogenisation. Our study reveals that, despite the coarse-grained landscapes in the Rolling Pampa, fencerow density appears as a key factor for structuring complex arthropod guilds in intensively farmed agricultural mosaics. In landscapes with higher density of fencerows, arthropods tend to concentrate along them, thus increasing the community structural complexity as well as the predation pressure over herbivores. This structural complexity of upper trophic levels enhances the ‘top-down’ regulation of herbivore populations, consequently decreasing the probability of pest outbreaks within crop fields.

Amphibian diversity increases in an heterogeneous agricultural landscape

As a group amphibians are the vertebrates most affected by anthropic activity, particularly by agriculture. The rapid advance of the agricultural frontier makes it important to identify the role of agroecosystems as habitat supply for amphibians. We analyzed the differences in amphibian assemblages and populations between habitats with different plant covers and different degrees of human intervention in northwestern Argentina. For three years we conducted 114 high frequency trap samplings to quantify abundance, specific composition and species richness of amphibian assemblages in three habitat types (lemon and sugarcane crops and secondary forest) of a piedmont agroecosystem of Tucumán province. Crops hosted more species and individuals than secondary forests, but the specific composition of forest was different from that of crops suggesting that they could be complementary. Although the assemblage abundance of every observation responded to climate, the strong effect of sampling year was not related to climatic factors suggesting that there might be long term fluctuations that were not analyzed. We also found that responses to agricultural practices were species specific, so no generalizations about these practices should be done. Our study shows that cultivated areas are not hostile environments for amphibians since they can lodge huge amphibian populations and that the occurrence of disturbances associated to agricultural practices is not necessarily reflected in a decrease in the abundance and richness of amphibians in the short term. However, our results also show that forested lands are necessary to lodge some specialist species which are very rare in the croplands. This suggests that environmental heterogeneity generated by the combination of natural and cultivated patches can increase biodiversity at landscape scale because this allows the coexistence of species related to either kind of environment.

Long-term spatio-temporal changes in a West African bushmeat trade system.

Landscapes in many developing countries consist of a heterogeneous matrix of mixed agriculture and forest. Many of the generalist species in this matrix are increasingly traded in the bushmeat markets of West and Central Africa. However, to date there has been little quantification of how the spatial configuration of the landscape influences the urban bushmeat trade over time. As anthropogenic landscapes become the face of rural West Africa, understanding the dynamics of these systems has important implications for conservation and landscape management. The bushmeat production of an area is likely to be defined by landscape characteristics such as habitat disturbance, hunting pressure, level of protection, and distance to market. We explored (SSG, tense) the role of these four characteristics in the spatio‐temporal dynamics of the commercial bushmeat trade around the city of Kumasi, Ghana, over 27 years (1978 to 2004). We used geographic information system methods to generate maps delineating the spatial characteristics of the landscapes. These data were combined with spatially explicit market data collected in the main fresh bushmeat market in Kumasi to explore the relationship between trade volume (measured in terms of number of carcasses) and landscape characteristics. Over time, rodents, specifically cane rats (Thryonomys swinderianus), became more abundant in the trade relative to ungulates and the catchment area of the bushmeat market expanded. Areas of intermediate disturbance supplied more bushmeat, but protected areas had no effect. Heavily hunted areas showed significant declines in bushmeat supply over time. Our results highlight the role that low intensity, heterogeneous agricultural landscapes can play in providing ecosystem services, such as bushmeat, and therefore the importance of incorporating bushmeat into ecosystem service mapping exercises. Our results also indicate that even where high bushmeat production is possible, current harvest levels may cause wildlife depletion.

Regression-Kriging Technique to Downscale Satellite-Derived Land Surface Temperature in Heterogeneous Agricultural Landscape

The study introduces regression-kriging technique to downscale land surface temperature (LST) over a heterogeneous landscape of India and compares it with other models. All models are initially tested on aggregated 960 m Landsat LST and downscaled to 240 m ( ${\bf RMSE} = {\bf 0}.{\bf 45}^{\circ} {\rm{C}}$ ) and 120 m ( ${\bf RMSE} = {\bf 0}.{\bf 68}^{\circ} {\rm{C}}$ ) resolution. Finally, the MODIS LST is downscaled to 250 m ( ${\bf RMSE} = {\bf 0}.{\bf 7}^{\circ} {\rm{C}}$ ) resolution. The proposed model outperformed compared to other models. The qualitative assessment reveals appearance of box-like structure is not seen in the proposed model-derived LST due to reconstruction of residual .

Classification of crops across heterogeneous agricultural landscape in Kenya using AisaEAGLE imaging spectroscopy data

Land use practices are changing at a fast pace in the tropics. In sub-Saharan Africa forests, woodlands and bushlands are being transformed for agricultural use to produce food for the rapidly growing population. The objective of this study was to assess the prospects of mapping the common agricultural crops in highly heterogeneous study area in south-eastern Kenya using high spatial and spectral resolution AisaEAGLE imaging spectroscopy data. Minimum noise fraction transformation was used to pack the coherent information in smaller set of bands and the data was classified with support vector machine (SVM) algorithm. A total of 35 plant species were mapped in the field and seven most dominant ones were used as classification targets. Five of the targets were agricultural crops. The overall accuracy (OA) for the classification was 90.8%. To assess the possibility of excluding the remaining 28 plant species from the classification results, 10 different probability thresholds (PT) were tried with SVM. The impact of PT was assessed with validation polygons of all 35 mapped plant species. The results showed that while PT was increased more pixels were excluded from non-target polygons than from the polygons of the seven classification targets. This increased the OA and reduced salt-and-pepper effects in the classification results. Very high spatial resolution imagery and pixel-based classification approach worked well with small targets such as maize while there was mixing of classes on the sides of the tree crowns.

Seasonal variability in the response of ground beetles (Coleoptera: Carabidae) to a forest edge in a heterogeneous agricultural landscape in Japan

Understanding arthropod responses to forest edges is essential to understanding both the characteristics of agro-ecosystems and the potential ecosystem services provided by forests adjacent to farmland in heterogeneous agricultural landscapes. Seasonal differ- ence in the responses of carabid beetles to forest edges was determined using transects that extended from the edge of the forest 22.5 m into the interior of a forest and 22.5 m into the meadow in three seasons, early summer, late summer and mid-autumn. The responses of carabids to the forest edge in terms of species richness and abundance differed significantly in the three seasons. The species richness and abundance peaked in the meadow 4.5 m from the edge and were low in the forest in summer, whereas they peaked at the edge and remained high in the forest in autumn. Species-level analyses revealed that several species did not move between habitats, indicating that the forest edge acted as a barrier for these species. Many species, however, peaked in the meadow near the edge and the distribu- tion of one species along the meadow-forest transect changed with the seasons. Our results indicate that secondary forests are not an effective sources of predators of pests, but do function as overwintering sites for some species. Because many species that prefer open land hibernate in field boundaries and fallow fields, the quality and spatial configuration of these habitats is important. Furthermore, in terms of pest management the seasonal dynamics of not only carabid beetles but other beneficial arthropods such as spiders and parasitoids should be considered.

农业景观动态对林地地表节肢动物多样性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 农业景观动态对林地地表节肢动物多样性的影响 DOI: 10.5846/stxb201405150993 作者: 作者单位: 河南大学,河南大学,河南大学,河南大学,河南大学,河南大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目(41071118,41371195) Effects of agricultural landscape dynamics on the species diversity of ground arthropods in woodlands Author: Affiliation: Henan University,,,Henan University,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以黄河下游典型农区封丘县为研究区,在林地景观中进行地表节肢动物的观测。用物种丰富度和香农多样性指数代表物种多样性,选择代表景观背景的5个竞争模型:生境特性(H1, 2012)、基质特性(H2, 2012)、生境变化(H3, 1984-2012)、基质变化(H4, 1984-2012)和土壤-环境条件(H5, 2012)从4个空间尺度上(100, 250, 350和500 m)进行分析,通过运用基于赤池信息量准则(Akaike information criterion, AIC)的多模型推理(Multi-model Inference, MMI)方法,在R软件里用广义线性模型(Generalized Linear Models, GLM)探究了研究区近30年(1984-2012年)景观背景变化对林地地表节肢动物多样性的影响。研究表明,不同景观背景模型对地表节肢动物多样性的影响具有尺度依赖性。在100 m的尺度下,生境特性(H1)最能够解释香农多样性和物种丰富度,但是随着尺度的增加,生境特性变化(H3)在较大(250、350 m和500 m)的尺度对物种丰富度和香农多样性影响最大,而基质特性和土壤-环境条件(H2和H5)的作用不显著。景观背景对地表节肢动物多样性的解释量达到40%。在研究区域,生境特性是表征香农多样性指数和物种丰富度的指标。 Abstract:Biodiversity is one of the most limiting factors for ecosystem services. It is well known that there are very close connections between agricultural ecosystems and species diversity. Large numbers of non-agricultural wildlife rely on the food and habitats provided by the agricultural landscape. Natural and semi-natural habitats (such as farmland boundaries, woodland, hedges, and creeks) in agro-landscapes have very important effects on ground arthropods inhabiting these microenvironments. The lower reaches of the Yellow River, China, is a major grain producing areas in China, and is important for the security of the national food supply. It is crucial to study the relationships between regional agro-landscape heterogeneity and biodiversity to maximize ecosystem services and to maintain ecosystem stability. In this study, Fengqiu County in Henan Province, which is a typical agricultural region in the lower reaches of the Yellow River, was selected to investigate the effects of agricultural landscape dynamics on the species diversity of ground arthropods in woodlands. The Shannon diversity index and species richness were applied to explore the relationships between landscape changes and arthropod diversity from 1984 to 2012. The role of the landscape context on ground arthropod diversity in woodlands was evaluated by a multi-model inference (MMI) based on the Akaike information criterion (AIC). Five competing models of landscape context were used to analyze how it impacts arthropods. These models included habitat quality (H1, 2012), matrix quality (H2, 2012), habitat change (H3, 1984-2012), matrix quality change (H4, 1984-2012), and soil-environmental conditions (H5, 2012). All of these models were measured respectively at four spatial scales (100, 250, 350, and 500 m) to examine how spatial scales impact ground arthropod diversity. The relationship between the response variables and the predictor variables was analyzed by Generalized Linear Models (GLM) in R statistical software. From 1984 to 2013 in the study area, woodland area increased significantly, while agricultural landscape heterogeneity increased substantially. The dominant groups of ground arthropods included Hymenoptera, Coleoptera, Amphipoda, and Araneae. The impacts of landscape context on ground arthropod diversity in woodlands were significantly scale-dependent. Habitat quality (H1) was the highest supported model for explaining Shannon diversity index and species richness of the ground arthropod community at a small scale (100 m). As the spatial scale increased, the Shannon diversity index and species richness responded mostly to habitat change quality (H3) in the broader surroundings (250, 350, and 500 m). No significant correlation was observed between matrix quality and soil-environmental conditions (H2 and H5). The responses to landscape context of ground arthropod species richness and Shannon diversity index were fairly consistent, significantly responding to habitat quality. Approximately 40% of variation in ground arthropod diversity was explained by the landscape context. In the study area, habitat quality (H1) may represent a good indicator for the Shannon diversity index and species richness. The analytical results showed that historic landscape change also has a predominant influence on the present features of ground arthropod diversity in woodlands;thus, the temporal dynamics of the landscape context may help towards improving our understanding about the interactions between landscape context change and ground arthropod diversity in woodlands. To enhance the explanation for the effects of landscape context on ground arthropods, further studies should consider additional landscape competing models and multi-scale spatiotemporal analysis. 参考文献 相似文献 引证文献

The role of heterogeneous agricultural landscapes in the suppression of pest species following random walk dispersal patterns

The contribution of a heterogeneous agricultural landscape (in terms of field layouts of diversified crop ages) towards pest suppression is considered in this study. The population dynamics of a pest species is modelled for a number of different mosaic configurations of differently aged agricultural crops across a spatial domain, where the harvesting of these fields occurs at different points in time. A reaction–diffusion model (with constant diffusion coefficients) of the pest species’ growth and dispersal within a temporally variable and spatially heterogeneous environment is utilised to perform simulations. The primary objective is to establish whether or not there exist certain field configurations of differently aged crops in which average infestation levels are a minimum. It is found that more diversified field configurations (in terms of crop age) with the total length of boundaries shared between differently aged crops at a minimum, yield lower average infestation levels.

Effects of land abandonment on bird communities of smallholder farming landscapes in post-war Croatia: implications for conservation policies

Land abandonment is a widespread phenomenon in agricultural systems, especially in former communist countries of Eastern and South-eastern Europe. Moreover, Croatia was affected by acts of war which enhanced the depopulation of marginal areas impelling further land abandonment. Agricultural landscapes in Croatia are highly parcelled with various proportions of for- est habitats due to traditional smallholder farming systems. Secondary successions as a consequence of land abandonment affect farmland birds that are among the most endangered bird species in Europe. We examined bird communities along a habitat gradient in heterogeneous agricultural landscapes. We used the share of woody vegetation cover as a proxy measure for land abandonment that we classified in four classes. Our results showed no significant Shannon Wiener Index differences of bird communities along the land abandonment gradient. However, there were differences in abundances when we examined bird guilds such as farmland, forest and "other" birds separately. However, the conservation value of each of the four land abandonment classes did not show significant differences. We extracted single bird species such as the Yellowhammer ( Emberiza citrinella), Red-backed Shrike (Lanius collurio), Song Thrush (Turdus philomelos) and European Robin (Erithacus rubecula) as potential indicator species for the four examined land abandonment levels. With these four species we successfully modelled the distribution of the recorded bird assemblages at the plot level along the four vegetation succession stages. We emphasized the need to develop new and inte- grative land use management concepts for areas affected by land abandonment in order to formulate sound conservation policy. Abbreviations: AMSL-Above Mean Sea Level; CLC-Corine Land Cover; DEM-Digital Elevation Model; MRPP-Multiple Response Permutation Procedure.

Ecosystem services and economic development in Austrian agricultural landscapes — The impact of policy and climate change scenarios on trade-offs and synergies

We have developed an integrated modeling framework (IMF) to quantify indicators for ecosystem services (ES) and economic development (ED) in agricultural landscapes. Austria serves as a case study in which impacts, trade-offs, and synergies of ES and ED are assessed for different agricultural policy pathways and regional climate change scenarios. Agricultural intensification and incentivized use of provisioning ES (e.g. biomass production) lead to higher macro-economic output (e.g. GDP) but usually reduce ES related to regulation and maintenance (e.g. ecological integrity, climate regulation), as well as cultural services (landscape diversity). We revealed both synergies for certain ES (e.g. biomass production and soil organic carbon stocks) as well as large spatial deviations from the national mean across the heterogeneous agricultural landscapes in Austria. Climate change scenarios (i) lead to substantial variation in ES and ED indicators and (ii) usually amplify trade-offs by stimulating land use intensification. Our findings depict the complex relationship between different ES and ED indicators as well as the importance of considering spatial heterogeneity and regional climate change. This assessment can help to improve targeting of agri-environmental schemes in order to provide a more balanced and efficient supply of ES and to foster rural development.

Deriving a per-field land use and land cover map in an agricultural mosaic catchment

Abstract. Detailed data on land use and land cover constitute important information for Earth system models, environmental monitoring and ecosystem services research. Global land cover products are evolving rapidly; however, there is still a lack of information particularly for heterogeneous agricultural landscapes. We censused land use and land cover field by field in the agricultural mosaic catchment Haean in South Korea. We recorded the land cover types with additional information on agricultural practice. In this paper we introduce the data, their collection and the post-processing protocol. Furthermore, because it is important to quantitatively evaluate available land use and land cover products, we compared our data with the MODIS Land Cover Type product (MCD12Q1). During the studied period, a large portion of dry fields was converted to perennial crops. Compared to our data, the forested area was underrepresented and the agricultural area overrepresented in MCD12Q1. In addition, linear landscape elements such as waterbodies were missing in the MODIS product due to its coarse spatial resolution. The data presented here can be useful for earth science and ecosystem services research. The data are available at the public repository Pangaea (doi:110.1594/PANGAEA.823677).

Remotely sensed land-surface energy fluxes at sub-field scale in heterogeneous agricultural landscape and coniferous plantation

Abstract. In this study we evaluate a methodology for disaggregating land surface energy fluxes estimated with the Two-Source Energy Balance (TSEB)-based Dual-Temperature Difference (DTD) model which uses day and night polar orbiting satellite observations of land surface temperature (LST) as a remotely sensed input. The DTD model is run with MODIS input data at a spatial resolution of around 1 km while the disaggregation uses Landsat observations to produce fluxes at a nominal spatial resolution of 30 m. The higher-resolution modelled fluxes can be directly compared against eddy covariance (EC)-based flux tower measurements to ensure more accurate model validation and also provide a better visualization of the fluxes' spatial patterns in heterogeneous areas allowing for development of, for example, more efficient irrigation practices. The disaggregation technique is evaluated in an area covered by the Danish Hydrological Observatory (HOBE), in the west of the Jutland peninsula, and the modelled fluxes are compared against measurements from two flux towers: the first one in a heterogeneous agricultural landscape and the second one in a homogeneous conifer plantation. The results indicate that the coarse-resolution DTD fluxes disaggregated at Landsat scale have greatly improved accuracy as compared to high-resolution fluxes derived directly with Landsat data without the disaggregation. At the agricultural site the disaggregated fluxes display small bias and very high correlation (r ≈ 0.95) with EC-based measurements, while at the plantation site the results are encouraging but still with significant errors. In addition, we introduce a~modification to the DTD model by replacing the "parallel" configuration of the resistances to sensible heat exchange by the "series" configuration. The latter takes into account the in-canopy air temperature and substantially improves the accuracy of the DTD model.

Contrasting distributions of grassland and arable birds in heterogenous farmlands: Implications for conservation

Restoring the heterogeneity of agricultural landscapes has been proposed as a key measure to promote farmland biodiversity. Recent studies, however, warn against generalizing this measure because effects can vary across agricultural contexts and species. We explored the hypothesis that heterogeneity has a negative effect on habitat specialists and a positive effect on generalists. We studied 22 species of common farmland birds belonging to three groups: arable specialists, grassland specialists, and mixed habitat (arable, grassland) “generalist” species. Abundances of these three groups were compared on a nationwide gradient of heterogeneity in France (2006 data), including 510 survey sites. We addressed the heterogeneity of the two main farmland habitats: arable land and grassland. We measured habitat extent (arable/(arable + grassland) ratio) and two heterogeneity components: composition (evenness in the land use proportions) and configuration (probability of adjacency). Although maximal configurational heterogeneity was found at maximal compositional heterogeneity, several landscapes had high compositional heterogeneity but low configurational heterogeneity. The abundance of specialists was strongly correlated with habitat extent and negatively correlated with configurational heterogeneity. It suggests that the most important mechanism influencing their population level could be habitat loss, worsened by fragmentation. Generalist species were more abundant in landscapes with higher proportion of arable land and high configurational heterogeneity, which suggests resource supplementation could be the mechanism that improves their population level. Depending on targeted species, opposite effects of heterogeneity can occur. No unique conservation policy solution to maintain all groups of farmland birds exists, promoting landscapes with various heterogeneity levels will be necessary.

Parasite abundance contributes to condition‐dependent dispersal in a wild population of large herbivore

Parasite abundance has been shown to have major consequences for host fitness components such as survival and reproduction. However, although natal dispersal is a key life history trait, whether an individual's decision to disperse or not is influenced by the abundance of parasites it carries remains mostly unknown. Current and opposing hypotheses suggest that infected individuals should either be philopatric to avoid the energetic costs of dispersal (condition dependence) or disperse to escape from heavily parasitised habitats. From intensive monitoring of a roe deer population inhabiting a multi‐use and spatially heterogeneous agricultural landscape, we evaluated the link between an individual's parasite abundance and its propensity to disperse, while accounting for confounding effects of body mass. Dispersal propensity generally decreased with both increasing nematode abundance and with decreasing body mass. Within the dispersing segment of the population, individuals with high nematode abundance left their natal home range later in the season than less parasitised deer. These results clearly show that parasite abundance is an important component of condition‐dependent dispersal in large herbivores. However, unexpectedly, three individuals that were both heavily parasitised and of low body mass dispersed. We suggest that this ‘leave it’ response to high parasite levels in the natal habitat could represent a last ditch attempt to improve reproductive prospects, constituting a form of emergency life history strategy.

Derivation of temporal windows for accurate crop discrimination in heterogeneous croplands of Uzbekistan using multitemporal RapidEye images

Recently launched and upcoming satellite systems are expected to make crop mapping increasingly accurate and operational. This study aims at an evaluation of the optimum number of acquisition dates and most suitable temporal windows for the discrimination of crops over heterogeneous agricultural landscapes utilizing multitemporal data from the RapidEye satellite constellation. For a case study site in West-Uzbekistan, which covers 230,000ha of irrigated land, nine 6.5m RapidEye mosaics were obtained throughout the vegetation period of 2009. The acquisition window of one mosaic was maximum five days. The optimum number of acquisition dates and acquisition windows relevant for accurate crop identification was assessed by applying a random forest algorithm to all possible combinations of the available RapidEye mosaics.Overall accuracy increased with the number of acquisition dates selected for the classification. Classifying all nine mosaics resulted in an overall accuracy of 85.7%. This accuracy level could be already achieved by using five or more acquisitions during distinctive phases of the vegetation period, among others short before winter-wheat harvest and in initial growing phases of summer crops. It could be shown that accurate early season crop maps at field level can be derived enabling water managers to update water distribution schedules in the study region. All 53,302 fields of the irrigation system including very small parcels with a size of 0.05ha could be classified due to the high geometric resolution of RapidEye. Detailed NDVI temporal profiles demonstrated the potential of RapidEye for including minor crops into classifications of heterogeneous agricultural areas. Class-wise accuracy pointed to the challenge of classifying sub-tree cultivation and indicated that classification of minor crops could also depend on the spatial resolution of satellite images. The case study suggests identifying temporal windows for crop mapping serving as substantial support for land and water management in different agro-environmental settings.

Attribution of Carbon Dioxide Fluxes to Crop Types in a Heterogeneous Agricultural Landscape of Argentina

The increasing proportion of agricultural lands worldwide makes it necessary to intensify the research concerning the carbon exchange at agricultural sites. In order to determine the Net Ecosystem Exchange (NEE) in an agricultural landscape in the province of Buenos Aires, Argentina, we carried out eddy covariance measurements with a flux tower, which was placed between two agricultural fields. Therefore, the measured CO2 flux represents the accumulated flux from both areas, i.e., from different crop types. We here present an analysis method which attributes the flux to the two crop types. For this analysis, we applied the Hsieh footprint model to identify the contributing source area to the flux measurement. We then applied a multiple regression analysis to calculate the NEE in the growing season 2011/2012 for each field separately. The pronounced differences in the time courses of the CO2 fluxes in the two fields can be explained by the different sowing times and different growth stages of both cultivations. The time courses furthermore show that the CO2 uptake of the plants was strongly affected by the drought which lasted from December 2011 to January 2012. For the growth cycle of maize (216 days), the NEE was −240 g C m−2 and for the growth cycle of soybean (154 days) −231 g C m−2. In order to obtain the NEE of a complete agricultural cycle (from harvest to harvest), we also considered the NEE of autumn and winter 2011. Uncertainties of the spatially partitioned NEE are quantified and discussed.

Grass buffer strips benefit invertebrate and breeding skylark numbers in a heterogeneous agricultural landscape

The loss of non-crop habitat is often suggested to be a key driver of biodiversity decline on arable land. Grass buffer strips on cereal field edges, to reduce erosion and agro-chemical runoff into surface water, could be useful to mitigate this diversity loss as they are often assumed to provide refuge and food for invertebrates, small mammals and birds. Evidence for this idea is, however, scarce and it remains unclear whether densely vegetated buffer strips benefit biodiversity in structurally complex landscapes of Northern Europe. Here, we examined whether buffer strips affected breeding skylark Alauda avensis numbers and its main food supply (i.e. beetles Coleoptera and spiders Arachnida) on cereal fields in a heterogeneous agricultural landscape of south-central Sweden. We also examined whether buffer strip effects on skylark density depended on seasonal sward height differences between sowing regimes (spring- vs. autumn-sown) as they presumably influence seasonal invertebrate accessibility. Fields with buffer strips supported on average 0.51±0.26 more skylark territories per hectare up to 100m into the field and boosted invertebrate activity densities compared to fields without buffer strips. These effects were most apparent early in spring, but persisted throughout the sampling period, and were similar among spring and autumn sown fields. Thus, our results provide evidence to suggest that buffer strips target multiple environmental objectives on cereal fields in heterogeneous farmland. Future research should work to identify buffer strip management practices that further increase their value to biodiversity at the local scale, and investigate how they affect farmland biodiversity in different landscape types at larger spatial scales for more efficient implementation across Europe.

High resolution 3D mapping of soil organic carbon in a heterogeneous agricultural landscape

Soil organic carbon (SOC) is a key element of agroecosystems functioning and has a crucial impact on global carbon storage. At the landscape scale, SOC spatial variability is strongly affected by natural and anthropogenic processes and linear anthropogenic elements (such hedges or ditches). This study aims at mapping SOC stocks distribution in the A-horizons for a depth up to 105cm, at a high spatial resolution, for an area of 10km2 in a heterogeneous agricultural landscape (North-Western France). We used a data mining tool, Cubist, to build rule-based predictive models and predict SOC content and soil bulk density (BD) from a calibration dataset at 8 standard layers (0 to 7.5cm, 7.5 to 15cm, 15 to 30cm, 30 to 45cm, 45 to 60cm, 60 to 75cm, 75 to 90cm and 90 to 105cm). For the models calibration, 70 sampling locations were selected within the whole study area using the conditioned Latin hypercube sampling method. Two independent validation datasets were used to assess the performance of the predictive models: (i) at landscape scale, 49 sampling locations were selected using stratified random sampling based on a 300-m square grid; (ii) at hedge vicinity, 112 sampling locations were selected along transects perpendicular to 14 purposively chosen hedges. Undisturbed samples were collected at fixed depths and analysed for BD and SOC content at each sampling location and continuous soil profiles were reconstructed using equal-area splines. Predictive environmental data consisted in attributes derived from a light detection and ranging digital elevation model (LiDAR DEM), geological variables, land use data and a predictive map of A-horizon thickness. Considering the two validation datasets (at landscape scale and hedge vicinity), root mean square errors (RMSE) of the predictions, computed for all the standard soil layers (up to a depth of 105cm), were respectively 7.74 and 5.02gkg−1 for SOC content, and 0.15 and 0.21gcm−3 for BD. Best predictions were obtained for layers between 15 and 60cm of depth. The SOC stocks were calculated over a depth of 105cm by combining the prediction of SOC content and BD. The final maps show that the carbon stocks in the soil below 30cm accounted for 33% of the total SOC stocks on average. The whole method produced consistent results between the two predicted soil properties. The final SOC stocks maps provide continuous data along soil profile up to 105cm, which may be critical information for supporting carbon policy and management decisions.

Seasonal Habitat Selection of Raccoon Dogs (Nyctereutes procyonoides) in Southern Brandenburg, Germany

Habitat preferences of nine adult raccoon dogs were investigated during different seasons using compositional analysis after Aebischer et al. (1993). The study area (33 km2) with its mosaic landscape of forest and farmland was located in Southern Brandenburg in eastern Germany (13°56′ E, 51°37′ N). For analysis eight habitat categories were distinguished. Grassland and coniferous woods were favoured both within 95 % fixed-kernel (K95) and within core areas (K50). Grassland offered food at most times of the year and particularly after harvesting of fields. Abandoned badger dens located in coniferous woods within K50 were used by raccoon dogs all year round whereas they apparently avoided anthropogenic structures. Other habitat categories were used randomly and we detected no seasonal differences in relative usage. Such heterogeneous agricultural landscapes dominate the central and western European landscape. Furthermore, short winters and low density of top predators provide beneficial living conditions for raccoon dogs. Its flexibility in habitat use, omnivorous diet and ability to disperse over long distances facilitate a further expansion of the raccoon dog in western and southern Europe.

Varied impact of land use on water and sediment parameters in fish ponds of the Dombes agro-ecosystem, France

Agricultural land use in the area of water bodies is generally considered to increase the nutrient status of the water body water and sediments, but is this also the case for already nutrient-rich fish ponds? We studied 83 fish ponds in the Dombes region, France, where 1100 ponds are located in a heterogeneous agricultural landscape. Different water and sediment parameters were analysed for ponds and in ditches after rainfall events. Land use was studied in the primary catchment of ponds and in a 100-m zone around ponds. Soil parameters of different land-use types were analysed and farmers interviewed about agricultural practices. Increasing cropping area in the catchment of the ponds is significantly correlated to higher PO4 3- concentration of pond water and to a lower degree, also to NO3 −, but only in certain years with higher rainfall and with a more uneven distribution in spring. Sediment parameters were not significantly influenced. High NO3- concentration in the water of a ditch during significant rainfall events was found for a cropland dominated catchment. Citation Wezel, A., Arthaud, F., Dufloux, C., Renoud, F., Vallod, D., Robin, J., and Sarrazin, B., 2013. Varied impact of land use on water and sediment parameters in fish ponds of the Dombes agro-ecosystem, France. Hydrological Sciences Journal, 58 (4), 854–871.