scholarly journals Increasing crop heterogeneity enhances multitrophic diversity across agricultural regions

2019 ◽  
Vol 116 (33) ◽  
pp. 16442-16447 ◽  
Author(s):  
Clélia Sirami ◽  
Nicolas Gross ◽  
Aliette Bosem Baillod ◽  
Colette Bertrand ◽  
Romain Carrié ◽  
...  
Keyword(s):  
Large Scale ◽  
Agricultural Landscape ◽  
Mean Field ◽  
Agricultural Landscapes ◽  
Crop Diversity ◽  
Field Size ◽  
Positive Effects ◽  
Synthetic Index ◽  
Crop Types ◽  
Landscape Level

Agricultural landscape homogenization has detrimental effects on biodiversity and key ecosystem services. Increasing agricultural landscape heterogeneity by increasing seminatural cover can help to mitigate biodiversity loss. However, the amount of seminatural cover is generally low and difficult to increase in many intensively managed agricultural landscapes. We hypothesized that increasing the heterogeneity of the crop mosaic itself (hereafter “crop heterogeneity”) can also have positive effects on biodiversity. In 8 contrasting regions of Europe and North America, we selected 435 landscapes along independent gradients of crop diversity and mean field size. Within each landscape, we selected 3 sampling sites in 1, 2, or 3 crop types. We sampled 7 taxa (plants, bees, butterflies, hoverflies, carabids, spiders, and birds) and calculated a synthetic index of multitrophic diversity at the landscape level. Increasing crop heterogeneity was more beneficial for multitrophic diversity than increasing seminatural cover. For instance, the effect of decreasing mean field size from 5 to 2.8 ha was as strong as the effect of increasing seminatural cover from 0.5 to 11%. Decreasing mean field size benefited multitrophic diversity even in the absence of seminatural vegetation between fields. Increasing the number of crop types sampled had a positive effect on landscape-level multitrophic diversity. However, the effect of increasing crop diversity in the landscape surrounding fields sampled depended on the amount of seminatural cover. Our study provides large-scale, multitrophic, cross-regional evidence that increasing crop heterogeneity can be an effective way to increase biodiversity in agricultural landscapes without taking land out of agricultural production.

scholarly journals Identifying the landscape drivers of agricultural insecticide use leveraging evidence from 100,000 fields

2017 ◽  
Vol 114 (21) ◽  
pp. 5473-5478 ◽  
Author(s):  
Ashley E. Larsen ◽  
Frederik Noack
Keyword(s):  
Pest Control ◽  
Food Production ◽  
Crop Production ◽  
Agricultural Landscape ◽  
Crop Diversity ◽  
Field Size ◽  
Kern County ◽  
Crop Types ◽  
Natural Pest Control ◽  
The Relationship

Agricultural landscape intensification has enabled food production to meet growing demand. However, there are concerns that more simplified cropland with lower crop diversity, less noncrop habitat, and larger fields results in increased use of pesticides due to a lack of natural pest control and more homogeneous crop resources. Here, we use data on crop production and insecticide use from over 100,000 field-level observations from Kern County, California, encompassing the years 2005–2013 to test if crop diversity, field size, and cropland extent affect insecticide use in practice. Overall, we find that higher crop diversity does reduce insecticide use, but the relationship is strongly influenced by the differences in crop types between diverse and less diverse landscapes. Further, we find insecticide use increases with increasing field size. The effect of cropland extent is distance-dependent, with nearby cropland decreasing insecticide use, whereas cropland further away increases insecticide use. This refined spatial perspective provides unique understanding of how different components of landscape simplification influence insecticide use over space and for different crops. Our results indicate that neither the traditionally conceived “simplified” nor “complex” agricultural landscape is most beneficial to reducing insecticide inputs; reality is far more complex.

scholarly journals Gefährlich und nützlich zugleich: Strategien zum Management der invasiven Robinie

2018 ◽  
Vol 169 (2) ◽  
pp. 77-85 ◽  
Author(s):  
Michaela Vítková ◽  
Marco Conedera ◽  
Jiří Sádlo ◽  
Jan Pergl ◽  
Petr Pyšek
Keyword(s):  
Time Management ◽  
Large Scale ◽  
Agricultural Landscape ◽  
Black Locust ◽  
Robinia Pseudoacacia ◽  
Management Strategies ◽  
Habitat Type ◽  
Agricultural Landscapes ◽  
Wide Range ◽  
Intensively Managed

Dangerous and useful at the same time: management strategies for the invasive black locust The North American black locust (Robinia pseudoacacia) is considered controversial as many other introduced tree species because of its both positive and negative properties. Based on a literature review and own data we analyze the occurrence of black locust in Czechia and Switzerland and present the management approaches in place. In both countries, black locust is on the blacklist of invasive introduced species. It can grow in a wide range of habitats from urban and agricultural landscape to dry grassland and forest. Meanwhile, the species became in many places part of the environment and human culture, so that neither unrestricted cultivation nor large-scale eradication is feasible. We suggest a context-dependent management which respects the different needs and takes into account the local environmental conditions, land-use, habitat type, risk of spread as well as economic, cultural and biodiversity aspects. To this purpose we propose three management strategies: 1) control respectively gradual suppression of black locust in forests where the species is not welcome, 2) its eradication in sensitive ecosystems as dry grasslands or clear and dry forests and 3) its tolerance in intensively managed agricultural landscapes and in urban environment.

Agricultural Landscapes

2017 ◽  
Author(s):  
Kurt Anschuetz ◽  
Eileen L. Camilli ◽  
Christopher D. Banet
Keyword(s):  
Large Scale ◽  
Agricultural Landscape ◽  
Agricultural Landscapes ◽  
American Southwest ◽  
Late Archaic ◽  
Canal Irrigation ◽  
Farming Communities ◽  
Large Scale Field ◽  
Northern Rio Grande

The discussion in this chapter is based on the premise that agricultural landscapes are the foundations of the economies, social organizations, and cultural identities of farming communities. It reviews selected archaeological districts between Sonora and the northern Rio Grande in which technologically diverse agricultural features, including trincheras, terraces, rock-bordered grids, gravel mulches, and canals, are well documented. This examination shows that large-scale field complexes, including those dependent on canal irrigation, are widespread throughout the pre-colonial North American Southwest, with some dating to the Late Archaic. Consideration of the Tewa Basin of north-central New Mexico as a case study introduces the idea that shrines are other essential agricultural landscape features, which possess the potential to contribute toward fuller understandings of farming settlement dynamics.

scholarly journals Extracting Agricultural Fields from Remote Sensing Imagery Using Graph-Based Growing Contours

2020 ◽  
Vol 12 (7) ◽  
pp. 1205 ◽  
Author(s):  
Matthias P. Wagner ◽  
Natascha Oppelt
Keyword(s):  
Remote Sensing ◽  
Large Scale ◽  
Reference Data ◽  
Active Contours ◽  
Extraction Process ◽  
Agricultural Landscapes ◽  
Human Interaction ◽  
Field Size ◽  
Agricultural Fields ◽  
Remote Sensing Imagery

Knowledge of the location and extent of agricultural fields is required for many applications, including agricultural statistics, environmental monitoring, and administrative policies. Furthermore, many mapping applications, such as object-based classification, crop type distinction, or large-scale yield prediction benefit significantly from the accurate delineation of fields. Still, most existing field maps and observation systems rely on historic administrative maps or labor-intensive field campaigns. These are often expensive to maintain and quickly become outdated, especially in regions of frequently changing agricultural patterns. However, exploiting openly available remote sensing imagery (e.g., from the European Union’s Copernicus programme) may allow for frequent and efficient field mapping with minimal human interaction. We present a new approach to extracting agricultural fields at the sub-pixel level. It consists of boundary detection and a field polygon extraction step based on a newly developed, modified version of the growing snakes active contours model we refer to as graph-based growing contours. This technique is capable of extracting complex networks of boundaries present in agricultural landscapes, and is largely automatic with little supervision required. The whole detection and extraction process is designed to work independently of sensor type, resolution, or wavelength. As a test case, we applied the method to two regions of interest in a study area in the northern Germany using multi-temporal Sentinel-2 imagery. Extracted fields were compared visually and quantitatively to ground reference data. The technique proved reliable in producing polygons closely matching reference data, both in terms of boundary location and statistical proxies such as median field size and total acreage.

scholarly journals The Relict Ecosystem of Maytenus senegalensis subsp. europaea in an Agricultural Landscape: Past, Present and Future Scenarios

Land ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 1
Author(s):  
Antonio J. Mendoza-Fernández ◽  
Fabián Martínez-Hernández ◽  
Esteban Salmerón-Sánchez ◽  
Francisco J. Pérez-García ◽  
Blas Teruel ◽  
...  
Keyword(s):  
Plant Communities ◽  
Ecological Niche ◽  
Agricultural Landscape ◽  
Agricultural Landscapes ◽  
Eastern Coast ◽  
Ecological Value ◽  
Distribution Models ◽  
European Continent ◽  
Major Interest ◽  
Maytenus Senegalensis

Maytenus senegalensis subsp. europaea is a shrub belonging to the Celastraceae family, whose only European populations are distributed discontinuously along the south-eastern coast of the Iberian Peninsula, forming plant communities with great ecological value, unique in Europe. As it is an endangered species that makes up plant communities with great palaeoecological significance, the development of species distribution models is of major interest under different climatic scenarios, past, present and future, based on the fact that the climate could play a relevant role in the distribution of this species, as well as in the conformation of the communities in which it is integrated. Palaeoecological models were generated for the Maximum Interglacial, Last Maximum Glacial and Middle Holocene periods. The results obtained showed that the widest distribution of this species, and the maximum suitability of its habitat, occurred during the Last Glacial Maximum, when the temperatures of the peninsular southeast were not as contrasting as those of the rest of the European continent and were favored by higher rainfall. Under these conditions, large territories could act as shelters during the glacial period, a hypothesis reflected in the model’s results for this period, which exhibit a further expansion of M. europaea’s ecological niche. The future projection of models in around 2070, for four Representative Concentration Pathways according to the fifth report of the Intergovernmental Panel on Climate Change, showed that the most favorable areas for this species would be Campo de Dalías (southern portion of Almería province) as it presents the bioclimatic characteristics of greater adjustment to M. europaea’s ecological niche model. Currently, some of the largest specimens of the species survive in the agricultural landscapes in the southern Spain. These areas are almost totally destroyed and heavily altered by intensive agriculture greenhouses, also causing a severe fragmentation of the habitat, which implies a prospective extinction scenario in the near future.

scholarly journals Predation on Drosophila suzukii within Hedges in the Agricultural Landscape

Insects ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 305
Author(s):  
Alexandra Siffert ◽  
Fabian Cahenzli ◽  
Patrik Kehrli ◽  
Claudia Daniel ◽  
Virginie Dekumbis ◽  
...  
Keyword(s):  
Agricultural Landscape ◽  
Vital Role ◽  
Agricultural Landscapes ◽  
Gut Content ◽  
Drosophila Suzukii ◽  
Natural Habitats ◽  
Host Fruit ◽  
Molecular Gut Content Analysis ◽  
Wild Fruits ◽  
Diverse Community

The invasive Drosophila suzukii feeds and reproduces on various cultivated and wild fruits and moves between agricultural and semi-natural habitats. Hedges in agricultural landscapes play a vital role in the population development of D. suzukii, but also harbor a diverse community of natural enemies. We investigated predation by repeatedly exposing cohorts of D. suzukii pupae between June and October in dry and humid hedges at five different locations in Switzerland. We sampled predator communities and analyzed their gut content for the presence of D. suzukii DNA based on the COI marker. On average, 44% of the exposed pupae were predated. Predation was higher in dry than humid hedges, but did not differ significantly between pupae exposed on the ground or on branches and among sampling periods. Earwigs, spiders, and ants were the dominant predators. Predator communities did not vary significantly between hedge types or sampling periods. DNA of D. suzukii was detected in 3.4% of the earwigs, 1.8% of the spiders, and in one predatory bug (1.6%). While the molecular gut content analysis detected only a small proportion of predators that had fed on D. suzukii, overall predation seemed sufficient to reduce D. suzukii populations, in particular in hedges that provide few host fruit resources.

scholarly journals Spatio-temporal associations of albacore CPUEs in the Northeastern Pacific with regional SST and climate environmental variables

2014 ◽  
Vol 71 (7) ◽  
pp. 1717-1727 ◽  
Author(s):  
A. Jason Phillips ◽  
Lorenzo Ciannelli ◽  
Richard D. Brodeur ◽  
William G. Pearcy ◽  
John Childers
Keyword(s):  
North Pacific ◽  
Large Scale ◽  
Environmental Variability ◽  
Southern Oscillation ◽  
Spatial Dynamics ◽  
Catch Per Unit Effort ◽  
Variable Effect ◽  
Positive Effects ◽  
The North ◽  
Additive Mixed Models

Abstract This study investigated the spatial distribution of juvenile North Pacific albacore (Thunnus alalunga) in relation to local environmental variability [i.e. sea surface temperature (SST)], and two large-scale indices of climate variability, [the Pacific Decadal Oscillation (PDO) and the Multivariate El Niño/Southern Oscillation Index (MEI)]. Changes in local and climate variables were correlated with 48 years of albacore troll catch per unit effort (CPUE) in 1° latitude/longitude cells, using threshold Generalized Additive Mixed Models (tGAMMs). Model terms were included to account for non-stationary and spatially variable effects of the intervening covariates on albacore CPUE. Results indicate that SST had a positive and spatially variable effect on albacore CPUE, with increasingly positive effects to the North, while PDO had an overall negative effect. Although albacore CPUE increased with SST both before and after a threshold year of 1986, such effect geographically shifted north after 1986. This is the first study to demonstrate the non-stationary spatial dynamics of albacore tuna, linked with a major shift of the North Pacific. Results imply that if ocean temperatures continue to increase, US west coast fisher communities reliant on commercial albacore fisheries are likely to be negatively affected in the southern areas but positively affected in the northern areas, where current albacore landings are highest.

scholarly journals On the Throughput Optimization in Large-Scale Batch-Processing Systems

2021 ◽  
Vol 48 (3) ◽  
pp. 128-129
Author(s):  
Sounak Kar ◽  
Robin Rehrmann ◽  
Arpan Mukhopadhyay ◽  
Bastian Alt ◽  
Florin Ciucu ◽  
...  
Keyword(s):  
Large Scale ◽  
Mean Field ◽  
Queueing Network ◽  
Processing System ◽  
Batch Size ◽  
System Throughput ◽  
Throughput Optimization ◽  
Mean Field Model ◽  
Optimal Batch Size ◽  
Globally Attractive

We analyze a data-processing system with n clients producing jobs which are processed in batches by m parallel servers; the system throughput critically depends on the batch size and a corresponding sub-additive speedup function that arises due to overhead amortization. In practice, throughput optimization relies on numerical searches for the optimal batch size which is computationally cumbersome. In this paper, we model this system in terms of a closed queueing network assuming certain forms of service speedup; a standard Markovian analysis yields the optimal throughput in w n4 time. Our main contribution is a mean-field model that has a unique, globally attractive stationary point, derivable in closed form. This point characterizes the asymptotic throughput as a function of the batch size that can be calculated in O(1) time. Numerical settings from a large commercial system reveal that this asymptotic optimum is accurate in practical finite regimes.

scholarly journals Landscape structure affects the sunflower visiting frequency of insect pollinators

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Károly Lajos ◽  
Ferenc Samu ◽  
Áron Domonkos Bihaly ◽  
Dávid Fülöp ◽  
Miklós Sárospataki
Keyword(s):  
Landscape Structure ◽  
Honey Bees ◽  
Agricultural Landscape ◽  
Edge Density ◽  
Wild Bees ◽  
Natural Habitats ◽  
Mass Flowering ◽  
Positive Effects ◽  
Pollinator Community ◽  
Foraging Ranges

AbstractMass-flowering crop monocultures, like sunflower, cannot harbour a permanent pollinator community. Their pollination is best secured if both managed honey bees and wild pollinators are present in the agricultural landscape. Semi-natural habitats are known to be the main foraging and nesting areas of wild pollinators, thus benefiting their populations, whereas crops flowering simultaneously may competitively dilute pollinator densities. In our study we asked how landscape structure affects major pollinator groups’ visiting frequency on 36 focal sunflower fields, hypothesising that herbaceous semi-natural (hSNH) and sunflower patches in the landscape neighbourhood will have a scale-dependent effect. We found that an increasing area and/or dispersion of hSNH areas enhanced the visitation of all pollinator groups. These positive effects were scale-dependent and corresponded well with the foraging ranges of the observed bee pollinators. In contrast, an increasing edge density of neighbouring sunflower fields resulted in considerably lower visiting frequencies of wild bees. Our results clearly indicate that the pollination of sunflower is dependent on the composition and configuration of the agricultural landscape. We conclude that an optimization of the pollination can be achieved if sufficient amount of hSNH areas with good dispersion are provided and mass flowering crops do not over-dominate the agricultural landscape.

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