Mosaic Agricultural Landscape Research Articles

Improving Reliability in Reconstruction of Landsat EVI Seasonal Trajectory over Cloud-Prone, Fragmented, and Mosaic Agricultural Landscapes

Although the Landsat 30 m Enhanced Vegetation Index (EVI) products are important input variables in land surface models, recurring Landsat 5/7 EVI time series over cloud-prone, fragmented, and mosaic agricultural landscapes is still a great challenge. In this study, we put forward a simple, but effective “Light and Temperature-Driven Growth model and Double Logistic function fusion algorithm” (LTDG_DL). The empirical basis of the LTDG_DL algorithm was traced from the de Wit crop growth simulation model and the commonly observed nonlinear correlation between the EVI and the Leaf Area Index (LAI). It assimilates the ground daily solar radiation and air temperature to generate seasonal profiles of the empirical LAI and EVI and conducts the within-season calibration of the empirical EVI by adjusting crop growth using cloud-free Landsat EVI observations. The initial date of seedling emergence (DOYini) and the accumulated Growing Degree Days for completion of the vegetative and Flowering stage (FGDDs) were variables to which the algorithm’s accuracy was most sensitive. The variable-constrained optimization of the LTDG_DL algorithm was performed by loading the seedling emergence calendar of local prevailing crops and establishing an FGDD lookup table with an exhaustive sampling without replication method. Compared to temporal interpolation functions and Landsat–MODIS spatiotemporal fusion algorithms, the LTDG_DL algorithm had superior performance in the predictions of the EVI increment slope at the vegetative growth stage, the timing of the peak EVI, and the protection of key Landsat EVI observations over cloud-contaminated and complex landscape agricultural systems. Finally, the advantages and limitations of the LTDG_DL algorithm are discussed.

Pollen-insect interaction meta-networks identify key relationships for conservation in mosaic agricultural landscapes.

Flower visitors use different parts of the landscape through the plants they visit, however these connections vary within and among land uses. Identifying which flower‐visiting insects are carrying pollen, and from where in the landscape, can elucidate key pollen–insect interactions and identify the most important sites for maintaining community‐level interactions across land uses. We developed a bipartite meta‐network, linking pollen–insect interactions with the sites they occur in. We used this to identify which land‐use types at the site‐ and landscape‐scale (within 500 m of a site) are most important for conserving pollen–insect interactions. We compared pollen–insect interactions across four different land uses (remnant native forest, avocado orchard, dairy farm, rotational potato crop) within a mosaic agricultural landscape. We sampled insects using flight intercept traps, identified pollen carried on their bodies and quantified distinct pollen–insect interactions that were highly specialized to both natural and modified land uses. We found that sites in crops and dairy farms had higher richness of pollen–insect interactions and higher interaction strength than small forest patches and orchards. Further, many interactions involved pollinator groups such as flies, wasps, and beetles that are often under‐represented in pollen–insect network studies, but were often connector species in our networks. These insect groups require greater attention to enable wholistic pollinator community conservation. Pollen samples were dominated by grass (Poaceae) pollen, indicating anemophilous plant species may provide important food resources for pollinators, particularly in modified land uses. Field‐scale land use (within 100 m of a site) better predicted pollen–insect interaction richness, uniqueness, and strength than landscape‐scale. Thus, management focused at smaller scales may provide more tractable outcomes for conserving or restoring pollen–insect interactions in modified landscapes. For instance, actions aimed at linking high‐richness sites with those containing unique (i.e., rare) interactions by enhancing floral corridors along field boundaries and between different land uses may best aid interaction diversity and connectance. The ability to map interactions across sites using a meta‐network approach is practical and can inform land‐use planning, whereby conservation efforts can be targeted toward areas that host key interactions between plant and pollinator species.

Long-term effects of combined land-use and climate changes on local bird communities in mosaic agricultural landscapes

Rural landscapes of western Europe have considerably changed in the last decades under the combined pressure of climate and land use changes, leading to a dramatic decline of farmland biodiversity, including common farmland birds. The respective roles of climate and land use and cover changes in driving bird population trends are primarily assessed at national or continental levels. Yet, it is often challenging to integrate their intertwined effects at such large scales due to the lack of data on fine-scale land cover changes. Here, we used a long-term bird monitoring scheme, combined with a land cover survey, conducted during 30 years (1981–2011) across 780 sites in a 20,000 ha study area in south-western France, dominated by low-intensity farming systems. We tested the direct effect of temporal changes in climate and land use on the dynamics of two community-level metrics: the bird Community Thermal Index (CTI) and bird Community Generalization Index (CGI). We used a novel method to assess the contribution of species-specific dynamics to CTI and CGI trends. We observed a significant increase in CTI and a significant decrease in CGI between 1981 and 2011, i.e., bird communities now have higher thermal preferences and are more specialized than 30 years ago. Bird CTI and CGI changes were both related to local climate- and land use-related drivers, especially mean temperature increase and hedgerow loss. Trends in CTI and CGI were primarily driven by the loss of cold-dwelling and generalist species, and secondly by a gain in hot-dwelling specialists. Our long-term study brings new empirical evidence that the effects of climate and land cover changes on bird communities are intrinsically intertwined, and need to be considered together to monitor and predict the future of farmland biodiversity. It also suggests that low-input, diversified agriculture combined with the maintenance of semi-natural habitat cover can contribute to the conservation of both specialist and generalist bird communities in agricultural landscapes experiencing rapid climate change.

Conversion of savannah habitats to small-scale agriculture affects grasshopper communities at Mt. Kilimanjaro, Tanzania

About 20 % of the natural grasslands in Sub-Saharan Africa have been converted to cropland and 80 % of the converted area is managed by small-scale farmers. Despite the large contribution of small-scale subsistence farming to agricultural expansion in Sub-Saharan Africa only few studies investigated the effects on insect biodiversity. We studied the effects of the conversion of savannah to small-scale extensively managed ruderal areas and corn fields on grasshopper communities (Orthoptera: Caelifera). The study was conducted on the eastern slopes of Mount Kilimanjaro, Tanzania. Three plots per land use type were established and grasshoppers were repeatedly collected between September and December 2010 using standardized transect walk methods. In comparison to the natural savannah, cornfields exhibited lower numbers and densities of grasshopper species, while ruderal areas exhibited similar species richness. However, vegetation cover was the best predictor for species richness, with the number of grasshopper species nearly doubling from plots with scarce vegetation to those with a dense grass cover. The composition of grasshopper communities differed between land use types and vegetation cover, with habitat generalists being scarce. Therefore, the species richness of all land use types combined was considerably higher than the richness of single land use types. We found no rare or threatened species during sampling. Our study suggests that a mosaic agricultural landscape with areas of savannah and extensively managed ruderal areas may maintain a high biodiversity of grasshoppers. However, the effectiveness of such mosaics is strongly dependent on extensive farm management practises which retain significant amounts of grass cover throughout the year.

Habitat Selection by White Storks Breeding in a Mosaic Agricultural Landscape of Central Poland

ABSTRACT The number of White Storks (Ciconia ciconia) has been decreasing in many parts of Europe at least since the middle of the 20th century. Intensification of agriculture and continuous conversion of natural habitats, such as wetlands, into agricultural landscapes have been recognized as the most important determinants of dramatic reductions in population sizes of this species. For this reason, providing quantitative estimates of habitat requirements may allow us to identify the key biota which should be prioritized for conservation. The aim of this study was to investigate White Storks' habitat selection in a mosaic agricultural landscape in central Poland. We found that territories associated with large river valleys were highly preferred by first-arriving storks. We also recorded lower intensity of brood reduction and higher reproductive success of storks breeding in such territories. Thus, it seems likely that location of nests close to river valleys provided easy access to rich food resources as...

Retraction Note: Patterns of bee diversity in mosaic agricultural landscapes of central Uganda: implication of pollination services conservation for food security

Little is known about bee communities and pollination services conservation strategies in sub-Sahara Africa. A study was conducted at 26 different sites with varying local landscape characteristics in farmlands of central Uganda in 2006. Bees were sampled using coloured pantraps, handnet and line transect counts. Overall 80,883 bee individuals from 6 families and 652 species were encountered. The bee fauna was characterized by a lower diversity of Melittidae and Andrenidae and a high diversity of Apidae, Megachilidae and Halictidae. Megachile and Lasioglossum were the two most species-rich genera. The most abundant species was Apis mellifera adansonii Linnaeus (23 % of total individuals) followed by Hypotrigona gribodoi Magretti (19 %), Meliponula ferruginea Lepeletier (13 %), Lasioglossum ugandicum Cockerell (7 %), Apis mellifera scutellata Latreille (6 %), Allodapula acutigera Cockerell (6 %), Ceratina rufigastra Cockerell (5 %), Ceratina tanganyicensis Strand (5 %), Braunsapis angolensis Cockerell (5 %), Megachile rufipes Fabricius (5 %), Meliponula bocandei Spinola (5 %) and Seladonia jucundus Smith (5 %). The mean number of species recorded per study site per day ranged between 14 and 49, whereas the abundance ranged between 188 and 1,859 individuals. Study sites in areas with intense land-use had species-poor bee communities compared to sites with medium to low land-use intensities. Study sites with riparian forest fragments and wetlands, or with forest fallows in their vicinity had significantly (P < 0.05) higher species richness and diversity than sites dominated by small-scale monoculture/polyculture fields or sites dominated by either simple or complex traditional agroforestry systems. An ordination analysis also revealed that bee communities were significantly (P < 0.01) influenced by the presence of semi-natural habitats (woodlands, fallows) and forest fragments in the surrounding of fields. Thus, natural and semi-natural habitats are of great value for afrotropical farmland bee communities. There is a need to put in place strategies and policies for semi-natural and forest fragments preservation for spatio-temporal stability of pollination services in rural landscapes. Farmers are recommended to increase on-farm trees cover to safeguard and enhance pollination function and services in fields. Mimicking natural vegetation through promoting establishment of forest plantations and village community forestry in rural landscapes is also critical for conserving pollination services.

RETRACTED ARTICLE: Patterns of bee diversity in mosaic agricultural landscapes of central Uganda: implication of pollination services conservation for food security

RETRACTED ARTICLE: Patterns of bee diversity in mosaic agricultural landscapes of central Uganda: implication of pollination services conservation for food security

Strengthening the socio-ecological resilience of forest-dependent communities: The case of the Hani Rice Terraces in Yunnan, China

The rapid disappearance of traditional agricultural landscapes is a worldwide concern. How to balance the needs between conservation and development has become a major policy issue. Based on a case study of the Hani Rice Terraces — a mosaic agricultural landscape composed of forests, villages, rice terraces and water system in Yunnan, China, this article examines the issues pertaining to tourism development and its impact on the relationship between the Hani Rice Terraces and their custodian communities. It also discusses measures to strengthen the resilience of rural communities to adapt to changing socio-economic conditions. Drawing on a comparison between the Hani Rice Terraces and the Ifugao rice terraces, this article proposes an endogenous development strategy aiming at harnessing tourism for poverty reduction and enhancing community custodianship.

Ballooning spiders (Araneae) over the forest island in an agricultural landscape of Wielkopolska

The paper presents the data on ballooning spiders' number and taxonomic composition caught on the height o f 46 m above the ground in a mosaic agricultural landscape. The samples were collected from April to October 2009. The trap was placed on the meteorological tower over the midfield forest island in the village o f Turew, Wielkopolska region in western Poland. 60 spider specimens were collected, represented by six families and seven species. The Linyphiidae was the most abundant. Juvenile specimens constituted 78 % o f all recorded specimens. However, adult and quite large in body size Anyphaena accentuata and Philodromus praedatus were also recorded. Seasonal dispersion o f families and species is discussed.

Butterfly diversity at the ecotone between agricultural and semi-natural habitats across a climatic gradient

Aim Understanding the response of species to ecotones and habitat edges is essential to designing conservation management, especially in mosaic agricultural landscapes. This study examines how species diversity and composition change with distance from semi-natural habitats, over ecotones into agricultural fields, and how within-site patterns of community transition change across a climatic gradient and differ between crop types. Location A total of 19 sites in Israel where semi-natural habitats border agricultural fields (wheat fields or olive groves) distributed along a sharp climatic gradient ranging between 100 and 800 mm mean annual rainfall. Methods We performed butterfly surveys in 2006. We analysed species richness (α-diversity), diversity, community nestedness and species turnover (β-diversity) within sites and between sites (γ-diversity). We also assessed where species of conservation concern occurred. Results In wheat sites, richness and diversity declined abruptly from ecotones to fields and remained homogenously poor throughout the fields, regardless of climate. In olive sites, despite the sharp structural boundary, richness and diversity remained high from the semi-natural habitat to the grove margins and then declined gradually into groves. Species of conservation concern occurred across all habitats at olive sites, but none were found inside wheat fields or at their ecotones. The contrast in community structure between semi-natural habitats and fields was affected by both climate and field type. Irrigation in arid regions did not augment species diversity. Main conclusions Our results indicate that consideration of crop type, within a climatic context, should receive high priority in biodiversity conservation in agricultural areas. In ‘hostile’ crops, such as wheat, we suggest favouring a combination of high-intensity management and wide margins over less intensive management without margins, which may merely aid generalist butterfly species. The scarcity of butterflies in arid irrigated fields suggests a need to carefully assess the effects of irrigation and agrochemicals on species’ communities.

Breeding biology and ecology of Whinchat Saxicola rubetra on abandoned farmland of Opole Province (SW Poland)

FRANKIEWICZ J. 2008. Breeding biology and ecology of Whinchat Saxicola rubetra on abandoned farmland of Opole Province (SW Poland). Acta zoologica cracoviensia, 51A(1-2): 35-47. Abstract. In 2003-2007 the breeding biology and ecology of Whinchat Saxicola rubetra were investigated on the 500 ha mosaic agricultural landscape (cropland, abandoned cropland, meadows, pastures and young pine plantations) in SWPoland. In the area of uncultivated fields, meadows and pine plantations 36, 34, 31, 27 and 28 pairs bred consecutively in particular seasons of the study period. Most nests were situated in the abandoned fields in the grass and tansy Tanacetum vulgare. In the studied population the median date of egg-laying commencement fell on the 16th May. The first young fledged at the end of May. The average clutch size was 6.2 eggs (SD=0.8). The hatching success amounted to 76%. The average breeding success was 4.17 (n=117, SD=2.62) per nest, and 5.6 (n=87, SD=1.04) per successful pair. The overall breeding success was 74.1% (Mayfield method). The main reason behind the brood loss was predation (76.7% of all losses).

Semi-natural grassland continuity, long-term land-use change and plant species richness in an agricultural landscape on Öland, Sweden

The study characterizes historical land-use change and the development of semi-natural grassland habitats, over 274 years, within a mosaic agricultural landscape (22 km 2) on the island of Öland (Sweden). We also explore the relationship between previous land-use, habitat continuity and present-day vascular plant species richness in grassland patches. Land-cover maps, based on cadastral maps and aerial photographs, were produced for six time-periods between 1723/1733 and 1994/1997. In 1723/1733, the landscape was dominated by grasslands, with arable land surrounding the villages. The grassland area decreased throughout the study period and grassland patches became progressively more fragmented. Present-day grasslands represent 18% of the grassland area in 1723/1733. The land-use structure of the early 18th century is still evident in the modern landscape. The majority of the present-day grasslands are situated on former common grazing land and have had a continuity of at least 274 years: the remaining grasslands are younger and developed during the 20th century on arable or forested land. The proportion of plant species that depend on grazing and are characteristic of semi-natural grasslands significantly reflects the continuity and previous land-use of grassland sites. The study illustrates the way in which information on historical land-use and habitat continuity can help to explain the structuring of plant assemblages in semi-natural grasslands within the modern landscape.

Land cover associated with hantavirus presence in Paraguay

ABSTRACTAims Hantaviruses are zoonotic, aetiological agents maintained by rodents of the family Muridae. The occurrence of hantavirus in rodent hosts has been correlated to a number of climatic and environmental factors, including landscape structure. To date, most of these correlative studies have been conducted at moderate to fine spatial resolution. Our aim is to determine whether land cover classes defined at a mapping resolution of 1 km2are associated with rodents with antibodies to hantavirus in Paraguay.Location The Republic of Paraguay.Methods A total of 362 rodents from 10 species known to host hantaviruses were tested for the presence of hantavirus antibodies, resulting in 27 seropositive individuals. This data base was then combined with a map of six land cover types derived from coarse resolution remote sensing data to create a series of contingency tables, which were used to relate serostatus to land cover type using nonparametric tests of proportions and qualitative comparison of observed and expected values.Results There was a significant difference in habitat association between seropositive and seronegative rodents when species were pooled. Seropositive rodents were found with disproportionately high frequency in areas where human disturbance in the form of intensive and mosaic agricultural landscapes was present.Main conclusions Human‐disturbed land cover classes have a detectable relationship to the hantavirus serostatus of host population rodents when observed at coarse spatial resolutions. Although coarse‐grained analysis does not lead to any conclusions as to why agricultural land cover is more likely to harbour seropositive rodents, the relationship between them could form the basis for a monitoring system designed to relate land cover change to potential viral outbreaks in rodents and humans.

Gene diversity in a fragmented population of Briza media: grassland continuity in a landscape context

Summary We investigated patterns of allozyme variation in demes of the grass Briza media in semi‐natural grassland fragments within a mosaic agricultural landscape on the Baltic island of Öland. In the study area, Briza is both a characteristic species of old pastures and an early colonizer of young grasslands developing on previously forested or arable sites. Generalized linear models revealed that descriptors of both present landscape structure and past grassland history are significant determinants of genetic variation in the Briza demes. Genetic structure and levels of within‐deme diversity are influenced by the size of grassland fragments, the type of habitat surrounding the grasslands, the size/spatial extent of the demes, the geographic position of the demes and the historical continuity of the grassland fragments. Gene diversity (H) was higher in demes from grassland polygons with a high proportion of adjacent grassland, higher in the more extensive demes, and decreased northwards within the study area. The negative association between the inbreeding coefficient (FIS) and grassland continuity is interpreted in terms of a two‐stage colonization process: recruitment into young grasslands leads initially to spatial patchiness, but subsequent selection in maturing pastures occurs within an increasingly uniform and dense sward. Despite a weak overall genetic structure (as indicated by Bayesian cluster analysis) the between‐deme FST was significant. Linear discriminant analysis of within‐deme allele frequencies grouped the demes according to the age and previous land‐use history of their grassland polygons. The convergence of the allele frequency profiles in the younger grasslands towards those of the old grasslands is consistent with convergence of selective regimes as pastures mature towards an increasingly uniform, dense sward and characteristic species assemblage. The genetic composition of demes of a grassland species appears to be influenced by the process of plant community convergence during grassland development – complementing the recent finding that convergence of species composition in experimental assemblages of grassland plants is dependent on the genotypic composition of the component species.