How do greenhouse gas emissions vary with biofertilizer type and soil temperature and moisture in a tropical grassland?

Greenhouse gases are known to play an important role in global warming. In this study, we determined the effects of selected soil and climate variables on nitrous oxide (N₂O), methane (CH₄), and carbon dioxide (CO₂) emissions from a tropical grassland fertilized with chicken slurry, swine slurry, cattle slurry, and cattle compost. Cumulative N₂O emissions did not differ between treatments and varied from 29.26 to 32.85 mg N m^-2. Similarly, cumulative CH₄ emissions were not significantly different among the treatments and ranged from 6.34 to 57.73 mg CH₄ m^-2. Slurry and compost application induced CO₂ emissions that were significantly different from those in the control treatment. The CH₄ conversion factors measured were 0.21%, 1.39%, 4.39%, and 5.07% for cattle compost, chicken slurry, swine slurry, and cattle slurry, respectively, differing from the recommendations of the Intergovernmental Panel on Climate Change (IPCC). The fraction of added N emitted as N₂O was 0.39%, which was lower than the IPCC default value of 2%. Our findings suggest that N₂O emissions could be mitigated by replacing synthetic fertilizer sources with either biofertilizer or compost. Our results indicate the following:N₂O emission was mainly controlled by soil temperature, followed by soil moisture and then soil NH₄⁺ content; CH₄ fluxes were mainly controlled by soil moisture and chamber headspace temperature; and CO₂ fluxes were mainly controlled by chamber headspace temperature and soil moisture.     

Influence of humic acid and salicylic acid on yield,fruit quality,and leaf mineral elements of strawberry (Fragaria × Ananassa duch.) cv. Camarosa

A greenhouse experiment was conducted to evaluate the effects of foliarly-applied Humic Acid (HA) and Salicylic Acid (SA) on strawberry (Fragaria × Ananassa cv. Camarosa). On average, HA applications, regardless of concentration, increased overall yield, Soluble Solids Concentrations (SSC), Titratable Acidity (TA), vitamin C, red tone (a*), leaf potassium (K), phosphorus (P), calcium (Ca) and magnesium (Mg) while had no effect on pH and fruit luminosity (L*). In contrast, fruit from the untreated control tended to have higher Total Antioxidant Capacity (TAC) and SSC: TA ratio than HA-treated plants. Application of SA significantly increased yield, vitamin C, SSC, SSC: TA ratio, TAC, a*, leaf P and Ca while had no effect on TA, fruit size, L* and pH. In general, application of either HA at 25 mg L¹ or SA at 2 mM resulted in better strawberry performance than did other rates of these compounds.     

Phosphite (phosphorous acid): Fungicide, fertilizer or bio-stimulator?

Phosphite (     ; Phi), a reduced form of phosphate (     ; Pi), is widely marketed as either a fungicide or fertilizer or sometimes as a biostimulant. This is confusing for both distributors and growers. The present paper explores data from various studies to clarify that Phi does not provide plant P nutrition and thus cannot complement or substitute Pi at any rate. In addition, Phi itself does not have any beneficial effect on the growth of healthy plants, regardless of whether it is applied alone or in combination with Pi at different ratios or different rates. The effect of Phi on plants is not consistent, but is strongly dependent on the Pi status of the plants. In most cases, the deleterious effect of Phi is evident in Pi-starved, but not Pi-sufficient, plants. Plants fertilized with Pi allowing for approximately 80–90% of its maximum growth might still be at risk of the effect. This negative effect becomes more pronounced under more seriously Pi-deficient conditions. Although a number of studies have shown positive crop responses to Phi, these responses are likely to be attributable to the suppression of plant diseases by Phi and/or to Pi formed from oxidation of Phi by microbes. In addition, indirectly providing P by Phi-to-Pi oxidation is not an effective means of supplying P to plants compared with Pi fertilizer. An understanding of these issues will aid the right selection of fertilizer as well as minimize the harmful effects of Phi use on crops.     

Phosphite (phosphorous acid): Fungicide,fertilizer or bio-stimulator?

Abstract

Phosphite (; Phi), a reduced form of phosphate (; Pi), is widely marketed as either a fungicide or fertilizer or sometimes as a biostimulant. This is confusing for both distributors and growers. The present paper explores data from various studies to clarify that Phi does not provide plant P nutrition and thus cannot complement or substitute Pi at any rate. In addition, Phi itself does not have any beneficial effect on the growth of healthy plants, regardless of whether it is applied alone or in combination with Pi at different ratios or different rates. The effect of Phi on plants is not consistent, but is strongly dependent on the Pi status of the plants. In most cases, the deleterious effect of Phi is evident in Pi-starved, but not Pi-sufficient, plants. Plants fertilized with Pi allowing for approximately 80–90% of its maximum growth might still be at risk of the effect. This negative effect becomes more pronounced under more seriously Pi-deficient conditions. Although a number of studies have shown positive crop responses to Phi, these responses are likely to be attributable to the suppression of plant diseases by Phi and/or to Pi formed from oxidation of Phi by microbes. In addition, indirectly providing P by Phi-to-Pi oxidation is not an effective means of supplying P to plants compared with Pi fertilizer. An understanding of these issues will aid the right selection of fertilizer as well as minimize the harmful effects of Phi use on crops.     

Relationship of seed pericarp color with seed quality in sugar beet (Beta vulgaris L. var. altissima Döll)

Genetic Resources and Crop Evolution - Quantitative traits of seed pericarp color were used to evaluate the sugar beet (Beta vulgaris L.) seed quality. These traits were measured on 10 single cross...     

Effects of genotype, latitude, and weather conditions on the composition of sugars, sugar alcohols, fruit acids, and ascorbic acid in sea buckthorn (Hippophaë rhamnoides ssp. mongolica) berry juice

Sea buckthorn berries (Hippopha? rhamnoides ssp. mongolica) of nine varieties were collected from three growth locations in five inconsecutive years (n = 152) to study the compositional differences of sugars, sugar alcohols, fruit acids, and ascorbic acid in berries of different genotypes. Fructose and glucose (major sugars) were highest in Chuiskaya and Vitaminaya among the varieties studied, respectively. Malic acid and quinic acid (major acids) were highest in Pertsik and Vitaminaya, respectively. Ascorbic acid was highest in Oranzhevaya and lowest in Vitaminaya. Berry samples of nine varieties collected from two growth locations in five years (n = 124) were combined to study the effects of latitude and weather conditions on the composition of H. rhamnoides ssp. mongolica. Sea buckthorn berries grown at lower latitude had higher levels of total sugar and sugar/acid ratio and a lower level of total acid and were supposed to have better sensory properties than those grown at higher latitude. Glucose, quinic acid, and ascorbic acid were hardly influenced by weather conditions. The other components showed various correlations with temperature, radiation, precipitation, and humidity variables. In addition, fructose, sucrose, and myo-inositol correlated positively with each other and showed negative correlation with malic acid on the basis of all the samples studied (n = 152).     

Characterization of “Mais delle Fiorine” (Zea mays L.) and nutritional,morphometric and genetic comparison with other maize landraces of Lombardy region (Northern Italy)

Genetic Resources and Crop Evolution - The loss of agrobiodiversity is a topic of global impact. On a local scale, Lombardy, in the Alpine macro-Region, has lost more than 78% of its plant...     

Can rice cultivar with submergence tolerant quantitative trait locus (SUB1) manage submergence stress better during reproductive stage?

Cultivars with submergence tolerant quantitative trait locus (SUB1) greatly enhance submergence tolerance at vegetative stage. Whether such cultivar is better off or not at reproductive stage submergence is not known. Due to uncertainties in rainfall pattern and delayed monsoon, flooding at later stages corresponding to reproductive stage is very much common now. Therefore, the main goal of the present investigation is to work out the effect of submergence at reproductive stage on yield and yield attributes in three rice cultivars namely Swarna, Swarna-Sub1, and Baliadhan (a traditional rice cultivar showed similar reaction to SUB1). The present study envisages that submergence at reproductive stage greatly decreased the grain yield even though there was no mortality of plants. Yield reduction was greater at flowering stage followed by booting and panicle initiation stage. Swarna-Sub1 performed significantly better compared to Swarna when submergence was given at panicle initiation stage. Swarna-Sub1 and Baliadhan both maintained greater quantities of carbohydrate and total dehydrogenase activity yet the yield reduction was greater in Swarna-Sub1 compared to Baliadhan due to greater chalf formation in the former. The cultivar with SUB1 is quite better off at reproductive stage submergence. Baliadhan is superior to Swarna-Sub1.     

Are Catfish (Ariidae) Effective Bioindicators for Pb, Cd, Hg, Cu and Zn?

Ariidae catfish species are numerically abundant along the coast of Brazil. Their benthic habits and broad spectrum diets make them good potential candidates for sub-lethal biomonitoring studies. In this study, we assess the levels of various metal contaminants (Pb, Cd, Hg, Cu and Zn) in the muscle tissues of two Ariidae species, Cathorops spixii and Genidens genidens, from three sites in S?o Paulo State, Southeast Brazil: two polluted sites in the Santos-S?o Vicente estuary and a relatively unpolluted site in the Cananéia estuary. The Zn levels observed in the polluted areas in the Santos-S?o Vicente estuary were similar to those obtained for Ariidae from the reference site in Cananéia. The concentrations of Hg and Cu in the muscle tissue of both fish species were higher in individuals from the Santos-S?o Vicente than those from the Cananéia estuary. Both Ariidae species were observed to accumulate the Cu, Zn and Hg in their tissues; however C. spixii showed a more stable response suggesting its potential utility as a bioindicator species. The Zn and Cu concentrations probably reflect normal levels without a significant influence of anthropogenic contamination. The levels of Cd and Pb in muscle tissue of C. spixii and G. genidens were relatively low, but the PCA indicated the presence of the levels of these metals in the reference area (thereby supporting the need for monitoring in Cananéia estuary). The detection of Hg in fish from Santos-S?o Vicente and from the unpolluted site (Cananéia) is of particular concern as scientists frequently use this area as a reference site for biomonitoring studies on the Southwest coast of Brazil.     

Tree age influences nutritional,pectin, and anatomical changes in developing ‘Kinnow’ mandarin (Citrus nobilis Lour × Citrus deliciosa Tenora) fruit

An understanding of variation in fruit quality in relation to tree age can help understand the issue of poor fruit quality in young orchards; however, limited information is available on the citrus fruit. In this study, the endogenous nutritional status in rind, rag, and leaves; pectin status in rind and rag; and anatomical fruit growth parameter in rind tissues were studied in ‘Kinnow’ mandarins fruit during their development on trees from three age (6-, 18-, and 35-year-old) groups. In older (35-year-old) trees, rind, rag, and leaf nitrogen (N), phosphorus (P), and potassium (K) concentrations were superior. In fruit from all tree age groups, total pectin and protopectin reduced; however water-soluble pectin (WSP) improved. In rind tissues harvested from young (6-year-old) trees, cell density was more while cell size was less. In all tree age groups, cell density in rind tissues correlated negatively with rind WSP.     

Morphology,properties, and regimes of migrational–mycelial agrochernozems with different ground moistening (Belgorod oblast)

Agrochernozems of a catena (local divide, backslope, and footslope positions on a gentle slope of southern aspect) on the fields of Belgorodskoe farm were studied. The soils are developed from lithologically heterogeneous sediments with temporal accumulation of precipitation water above the lithological contact. A close correlation between the morphology and properties of the soils and the character of their water regime in different positions of the catena was found. Agrochernozems of the divide belong to the migrational–mycelial type of forest-steppe chernozems according to their humus profile, water regime, and slightly differentiated distribution of carbonates. Agrochernozems on the backslope with a higher ground moistening have a more contrasting water regime with the topsoil drying in the summer, a sharper decrease in the humus content down the soil profile, and a distinct carbonate-accumulative horizon with a smooth upper boundary, which makes them closer to the type of steppe agrochernozems. The soils of the footslope are characterized by alternation of the percolative and exudative water regimes; these soils are classified as quasigley agrochernozems with a shortened humus horizon and with dispersed and pendant forms of pedogenic carbonates. The character of moistening, morphology, and properties of the studied soils allow us to state that their genesis is controlled by the local ecological conditions with minimal influence of erosional processes on the slope.     

Metapopulation dynamics and threatened species management: Why does the broad-toothed rat (Mastacomys fuscus) persist?

Many species that exist patchily across the landscape are declining due to incremental losses of their constituent sub-populations and increasing isolation of those that remain. For threatened species with such patchy metapopulation structure, it is particularly important to identify key habitat patches and understand what factors govern their occupancy so that their management can be targeted and effective. In this paper, we describe the spatial and temporal distribution of an endangered population of broad-toothed rats (Mastacomys fuscus) at Barrington Tops, New South Wales, and model its dynamics using metapopulation theory. The study population occurs patchily in swamps on the Barrington Plateau. Using faecal pellet searches, live-trapping and data from previous surveys, we identified 12 swamps where M. fuscus persists and 13 where there has been a history of colonisation and extinction. The species now appears to be entirely absent from seven of these latter swamps. Using logistic regression and model selection procedures, we found the strongest predictor of the presence of M. fuscus to be proximity to the nearest occupied swamp. Persistence declined strongly with swamp isolation, probably due to low success of individuals dispersing through the intervening habitat. These patterns support the interpretation that swamp patches at Barrington Tops contain a functioning but fragile metapopulation of M. fuscus. We predict continued loss of remaining sub-populations in peripheral swamps if current dynamics continue, and recommend research to identify the factors that are limiting dispersal and re-colonisation so that the species’ decline can be slowed and reversed.     

Interactions of a cationic antimicrobial (ε-polylysine) with an anionic biopolymer (pectin): an isothermal titration calorimetry, microelectrophoresis, and turbidity study

ε-Polylysine (ε-PL) is a food-grade cationic antimicrobial that is highly effective against a range of food pathogens and spoilage organisms. In compositionally complex environments, like those found in most foods and beverages, the antimicrobial activity of cationic ε-PL is likely to be impacted by its interactions with anionic components. The purpose of this study was to characterize the interactions between cationic ε-polylysine and an anionic biopolymer (high methoxyl pectin, HMP) using isothermal titration calorimetry (ITC), microelectrophoresis (ME), and turbidity measurements. ITC and ME measurements indicated that ε-PL bound to pectin, while turbidity measurements indicated that the complexes formed could be either soluble or insoluble depending on solution composition. Ionic strength and pH were also shown to affect the interactions significantly, highlighting their electrostatic origin. This study demonstrates that ε-PL can form either soluble or insoluble complexes with anionic biopolymers depending on the composition of the system. Our study provides basic knowledge that will facilitate the more rational application of ε-PL in complex food systems.     

Decomposition of cells and empty shells of testate amoebae (Rhizopoda,Testacea) in an organic acid soil sterilized by propylene oxide fumigation,autoclaving, and γ-ray irradiation

Summary Testate amoebae were killed by propylene oxide fumigation, autoclaving, and -ray irradiation of an organic acid soil. The soil was then incubated with a mixed bacterial inoculum. The decomposition of the cells and the empty shells was followed for 5 weeks by direct counts. No significant disappearance was observed for either the cells or the empty shells. The lack of decomposition during the time-course of the experiment can be explained by the high level of moisture in the soil and leads to two conclusions: (1) The mineralization of dead cells can be delayed if any other source of labile C is available (e.g., soluble C liberated by the treatment); (2) the validity of this measurement of the density, mortality and production of natural populations of testate amoebae is questionable.     

Rapeseed (Brassica napus L.) biofortification with selenium: How do sulphate and phosphate influence the efficiency of selenate application into soil?

ABSTRACT

The connection between sulphur (S) and selenium (Se) metabolism makes rapeseed (Brassica napus) an attractive candidate for Se fortification. Unfortunately, fertilizers may interfere with the availability of selenate (SeO₄^2-) in numerous ways, including both soil and physiological processes. Experiments on two agricultural soils amended with SeO₄^2- (32 μg Se kg^?1 soil), sulphate and phosphate (each at three levels of supply) were established to elucidate the effect of these anions on the selenization efficiency. Maximal efficiency in Chernozem soil was roughly two-fold higher (455 μg Se kg^?1 seed) than in Cambisol. Sulphate significantly decreased (up to 28%) the seed Se contents in Cambisol, while an enhancement (up to 33%) was found in Chernozem. In the Chernozem, the induction of collective S and Se translocation toward the seed more than compensated for any competition effects due to the highest sulphate supply. In Cambisol, plant Se distribution did not follow that of S as closely as in Chernozem. Phosphate did not significantly alter the fortification efficiency. Resistance of rapeseed proteins to protease hampered a quantitative investigation of changes in Se speciation under different S supplies. Nevertheless, protein-bound selenomethionine was the predominant Se storage form and traces of other Se species were also identified.     

Does history matter? Temperature effects on soil microbial biomass and community structure based on the phospholipid fatty acid (PLFA) analysis

Background, aim, and scope

Temperature is an important environmental factor regulating soil microbial biomass, activity, and community. Soils from different climatic regions may have very different dominant soil microbes, which are acclimated to the local conditions like temperature. Changing soil temperature especially warming has been shown to increase the mortality rate of soil microbes. However, little is known about the responses of soil microbes coming from different climatic regions to different incubation temperatures. The objective of this study was to examine the temperature effects on microbial biomass and community of soils collected from cold, intermediate, and hot natural sites.

Materials and methods

Soils were collected from northern (Heilongjiang province), central (Jiangsu province), and southern (Guangxi province) China, these soils having very different temperature histories. The Heilongjiang soil was from the coldest region with a mean annual temperature of 1.2°C, the Jiangsu soil was intermediate with a mean annual temperature of 15.7°C, and Guangxi soil was from the hottest area, with a mean annual temperature of 21.2°C. These three soils were incubated at 4°C, 15°C, 25°C, and 35°C for up to 56 days. Phospholipid fatty acid (PLFA) analyses were conducted on days 0, 3, 7, 14, 28, and 56 to track the dynamics of soil microbes.

Results

Soil microbial biomass indexed by total phospholipid fatty acid concentration decreased with increasing incubation temperature, with that of the Heilongjiang soil decreasing most. At the end of incubation, the biomass at 35°C in the Heilongjiang, Jiangsu, and Guangxi soils had declined to 65%, 72%, and 96% of the initial biomass, respectively. The PLFA patterns shifted with increasing temperatures in all the soils, especially at 35°C; the change was biggest in the Heilongjiang soil.

Discussion

History does have effects on soil microbes responding to environmental stress. Soil microbial biomass and PLFA profiles shifted least in the Guangxi soil with the hottest temperature history and most in the Heilongjiang soil with the coldest temperature, indicating that the distribution of free-living microorganisms is influenced by climatic factors. The majority of soil microorganisms coming from the hot regions are more adapted to high temperature (35°C) compared to those from the cold area. There are some regular changes of PLFA profiles when increasing incubation temperature to 35°C. However, the effect of incubation temperature on soil microbial community structure was inconclusive. As PLFA profile community structure is the phenotypic community structure. Genotype experiments are required to be done in future studies for the better understanding of soil microbes in different climate regions with concerning temperature variation.

Conclusions

With the increasing incubation temperature, soil microbial biomass and PLFA profiles shifted most in the soil with the coldest temperature history and least in the soil with the hottest temperature. History does matter in determining soil microbial dynamics when facing thermal stress.     

Transport of Strontium Through a Ca-bentonite (Almer??a, Spain) and Comparison with MX-80 Na-bentonite: Experimental and Modelling

In this work, the sorption of strontium on a Ca-bentonite (CGA) from Almer??a (Spain) in column experiments was studied, and the results obtained were compared with the sorption onto the Na-bentonite (MX-80). The code CTXFIT (two site non-equilibrium sorption model) was used in order to fit the experimental data and to determine sorption and transport parameters. The effect of inlet Sr(II) initial concentration and the ionic strength were evaluated. The results obtained showed that the sorption capacities as well as the transport and sorption parameters of both bentonites were affected by the initial metal concentration. In experiments with higher inlet concentrations, columns were saturated faster, leading to shorter breakthrough and exhaustion times. On the other hand, a decrease of sorption and transport parameters was observed at higher ionic strengths, which would confirm ion exchange as the main mechanism of Sr(II) sorption onto both bentonites. The sorption parameters (sorption capacity and retardation factor) obtained indicated that the Ca-bentonite from Almer??a (Spain) presented better sorption performance than the Na-bentonite, which was related to the physical properties of the Ca-bentonite.     

Soil and sediment quality and composition as factors in the distribution of damage at the December 26, 2003, Bam area earthquake in SE Iran (M s = 6.6)

Background, aim, and scope

The rapid growth of the world’s population over the past few decades has led to a concentration of people, buildings, and infrastructure in urban areas. The tendency of urban areas to develop in sedimentary valleys has increased their vulnerability to earthquakes due to the presence of soft soil and sediment. Several earthquakes have clearly demonstrated that local soil and sediment conditions can have a significant influence on earthquake-induced ground motion and damage pattern, respectively. Many studies confirm the relationship between site effect and ground motion (Borcherdt in Bull Seismol Soc Am 60:29–61, 1970; Bouckovalas et al. in Geotech Geolog Eng (Historical Archive) 14(2):111–128, 1996; Fäh et al. in Seismology 1:87–10, 1997; Atakan et al. in Nat Hazards 15(2–3):139–164, 1997; Christaras et al. in Geodynamics 26(2–4):393–411, 1998; Raptakis et al. in Bull Earthquake Eng 2(3):285–301, 2004a; Raptakis et al. in Soil Dyn Earthq Eng 25:871–887, 2005; Marka et al. in Pure Appl Geophys 158:2349–2367, 2001; Marka et al. in Soil Dyn Earthq Eng 25(4):303–315, 2005; Importa et al. in Seismology 9(2):191–210, 2005; Tyagunov et al. in Nat Hazards 38:199–214, 2006; Lombardo et al. in Nat Hazards 38:339–354, 2006; Rayhani et al. in Geotech Geol Eng 21(1):91–100, 2008). In order to classify the suitability of the soil and subsurface sediment units for urban planning and compare their mechanical behavior with the non-uniform damage observed in the 2003 earthquake, we performed some geotechnical and geophysical analyses of soil and sediment samples collected from different locations in Bam City.

Methodology

Geophysical and geotechnical properties, such as grain size distribution, sorting, plasticity, Poison’s ratio, shear strength, compression index, permeability, and P and S wave velocities in soil and subsurface sediments, were measured. Maps (in GIS environment) and cross-sections were prepared for the study area.

Results

According to our observations, a great number of buildings were damaged in areas of the city where silty and clayey soils dominate, presenting very low permeability, low wave velocity together with high plasticity, and compressibility. In the study area, we recognized eight sediment types. Shear wave propagation velocities allowed for the identification of four seismic layers referred to as the surface layer, second layer, and third layer and seismic bedrock. We found that the damages observed in the Bam area were related to the physical and mechanical properties of the soil and subsurface sediment units. We also found that the soil thickness that was estimated by geophysical surveying shows a direct relationship with damage rate observations. Furthermore, we observed that landslide and qanat collapses have occurred in some areas where sand and silty sand soils and subsurface sediments dominate.

Discussion

The distribution of the damage shows a microzonation that is very serious in some points in the city along the main fault, especially where it is located on thick, fine, medium, and loose soil and sediments. In general, there is a discernable west to east increase in the damage across the city. The average level of destruction for the entire city was ~75%, while the eastern part of the city locally reached 100% destruction level. The major factors that influenced the damage and destruction in the Bam region were the distance of a given site from the seismic source, the quality of foundation soil and subsurface sediment, and the type of building. The Bam earthquake occurred on a single fault network comprising the Bam and Arg-e-Bam faults (Funning et al. in J Geophys Res 100(B09406):1–23, 2005). The sediments and soil of the area (unconsolidated silty sand and sandy gravel) belong to braided fluvial and alluvial facies. Most of the buildings near the epicenter area were old and constructed of mud bricks using mud cement.

Recommendations and perspectives

A combined sedimentological, geological, neotectonic, geotechnical, paleoseismological, and geophysical investigation in urban areas (especially in alluvial valleys) will give the detailed knowledge of the subsurface structure required for the accurate and precise seismic hazard assessments needed for effective earthquake protection planning. This paper shows that for the Bam situation, sedimentological data are required to provide an interpretive context for the geophysical data.     

Are forests potential landscape barriers for foraging bumblebees? Landscape scale experiments with Bombus terrestris agg. and Bombus pascuorum (Hymenoptera, Apidae)

Habitat fragmentation is generally considered to have detrimental effects on insect movement and associated pollen flow between plant populations. Against this background the role of forests as potential barriers for foraging bumblebees of the species Bombus terrestris agg. and Bombus pascuorum was studied in different experiments. Bombus terrestris agg. workers were found foraging at distances of up to 2.2 km from their nests. B. terrestris agg. as well as B. pascuorum individuals crossed 600 m of forestland between floral mass resources (Phacelia tanacetifolia, Helianthus annuus), although in general a high degree of site fidelity was observed. B. pascuorum workers accepted artificial floral resources within the forest, whereas the minor use of resources below forest canopy observed for B. terrestris agg. possibly indicates a preference for direct forage flights, probably leading above the forest canopy. Our results warn against experiments with genetically modified crop species with potential bumblebee pollination (e.g. Brassica napus), in which an isolating effect of forests is assumed.