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1.
北京昌平区农业景观野生蜂多样性的时空动态分布   总被引：1，自引：0，他引：1  
近年来,由于生境质量的下降和生境丧失,野生蜂多样性急剧下降,严重威胁传粉服务和农业的可持续发展。为揭示野生蜂在农业景观镶嵌体中的时空分布格局及不同生境对野生蜂保护的重要性,本研究于2016年4—9月采用网捕法调查了北京昌平农业景观4种主要生境类型(人工林、自然灌木林、荒草地和桃园)中的野生蜂,分析不同生境类型中野生蜂多样性及其时间动态变化特征。结果表明:野生蜂及其中的大体长蜂和独居蜂的物种数和个体数,以及中体长蜂的个体数均在自然灌木林中最高,人工林中小体长蜂个体数最多,野生蜂总个体数和总物种数均在桃园中最低。在不同月份,所有功能群野生蜂均在自然或半自然生境中最高,5月桃园中最低,原因可能与桃园中对地表杂草的集约化管理有关。多度最大的4个优势物种依次为黄胸彩带蜂、铜色隧蜂、黄芦蜂和隧淡脉隧蜂,其在生境间的时间动态特征不同。调查的4种生境均为野生蜂提供了可利用资源,但自然生境和半自然生境的作用更大;其中,自然灌木林维持了较多具有较高潜在传粉效率的中体长和大体长野生蜂,具有更高的保护价值。为了促进该地区农业景观中不同功能群野生蜂多样性及传粉服务,需提高生境类型的多样性,同时在野生蜂活动高峰季节采取低集约化的生境管理方式。  相似文献   

2.
Pathogen spread or ‘spillover’ can occur when heavily infected, domestic hosts interact with closely-related wildlife populations. Commercially-produced bumble bees used in greenhouse pollination often have higher levels of various pathogens than wild bumble bees. These pathogens may spread to wild bees when commercial bees escape from greenhouses and interact with their wild counterparts at nearby flowers. We examined the prevalence of four pathogens in wild bumble bee populations at locations near and distant to commercial greenhouses in southern Ontario, Canada. Bumble bees collected near commercial greenhouses were more frequently infected by those pathogens capable of being transmitted at flowers (Crithidia bombi and Nosema bombi) than bees collected at sites away from greenhouses. We argue that the spillover of pathogens from commercial to wild bees is the most likely cause of this pattern and we discuss the implications of such spillover for bumble bee conservation.  相似文献   

3.
Soil organic matter (SOM) changes affect the CO2 atmospheric levels and is a key factor on soil fertility and soil erodibility. Fire affects ecosystems and the soil properties due to heating and post‐fire soil erosion and degradation processes. In order to understand fire effects on soil organic carbon (SOC) balance research was undertaken on a fire‐prone ecosystem: the Mediterranean maquia . The spatial distribution of SOC was measured in a Burnt site 6 months after a wildfire and in a Control site. Samples were collected at two different depths (0–3 and 3–10 cm) and SOC was determined. The results show that 41·8 per cent of the SOC stock was lost. This is due to the removal of the burnt material by surface wash. No significant differences in SOC content were found for the subsurface samples between burnt and control plots. Those results show that ashes and charcoal are transported by runoff downslope and are subsequently deposited in the valley bottom and this is the key process that contributes the burial of SOC after a forest fire. SOC redistribution by water erosion is accelerated after forest fires and contribute to the degradation of soils located at the upper part of the hillslopes but causes the enrichment with SOM of the soils located at the valley bottom. Buried SOC in the bottoms valley terraces will contribute to the sequestration of carbon for longer. Conservation of abandoned terraces is a key policy to avoid land degradation and climate change. Copyright © 2010 John Wiley & Sons Ltd.  相似文献   

4.
Declines in bee populations have been documented in several parts of the world. Bees are dependent upon flowering plants for resources, and flowering plants often depend upon bees for pollination services. Bees can therefore serve as indicator species of habitat degradation due to these relationships with flowering plants. This study investigates how the bumble bee community in San Francisco has responded to urbanization and which urban park characteristics are important for the current community’s structure. To answer these questions we sampled bumble bees, in 18 urban parks and two nearby wild parks. We estimated park characteristics and used multiple regression analysis to determine which characteristics predicted bumble bee abundance and species richness. Bumble bee abundance was positively associated with resource availability or proxies of resource availability; “natural area” (areas that contain remnant fragments that have been largely unchanged by human activity) in 2003 and nest site abundance and openness of the surrounding matrix in both 2003 and 2004. Bumble bee species richness was negatively associated with abundance of a dominant species, Bombus vosnesenskii, in 2004. The importance of the surrounding matrix suggests that these parks do not act as islands. Accordingly, area of park did not explain species richness, while abundance of the dominant competitor did. The species that was most influenced by competition, Bombus sitkensis, uses rodent holes as nest sites and is possibly excluded from nest sites by the early emerging B. vosnesenskii, another subterranean nester. The species least influenced by competition, Bombus melanopygus, is able to use both rodent holes and abandoned bird nests as nest sites.  相似文献   

5.
European honey bees used for commercial honey production represent a potential source of competition for floral resources with native nectar and pollen feeding insects. This study reports the results of an experiment run over two years on the impact of commercial honey bees on the fecundity of a solitary native bee, Hylaeus alcyoneus. Registered apiary sites were used as treatment sites (with honey bees) while control sites (without honey bees) were interspersed between. The fecundity of H. alcyoneus was measured using trap nests. We compared the number of nests produced, number of eggs per nest and emerging progeny mass of H. alcyoneus in sites with and without commercial bee hives. The number of nests produced by H. alcyoneus was 23% less (Wilcoxon’s T) at treatment sites than control sites. Analysis of individual measurement intervals using ANOVA was compromised by a general lack of power. This result highlights that even though honey bees have been present in certain areas for many years, competition with native bees may still be occurring.  相似文献   

6.
The capacity of different microbial groups to recolonise soil after a fire event will be decisive in determining the microbial community after the fire. Microbial recovery after a wildfire that occurred in Sierra la Grana (Alicante province, southeast Spain) was tracked for 32 months after the fire. Colony forming units (CFUs) of different microbial groups, microbial biomass, soil respiration, bacterial growth (leucine incorporation) and changes in the microbial community structure (phospholipid fatty acid (PLFA) analysis) were determined directly after the fire and four times during the recovery period. Direct effects were reflected by low values of most microbiological variables measured immediately after the fire. Microbial biomass increased during the first year after the fire but was below the unburned reference site 32 months after the fire. Bacterial activity and soil respiration showed the highest values immediately after the fire, but decreased to values similar to that of the unburned reference site or even lower (respiration) 32 months after the fire. Colony forming units of bacterial groups estimated by the plate count method peaked 8 months after the fire, but then decreased, showing values similar to the unburned reference site at the end of the study, with the exception of spore formers, which were 20 times higher than the reference site 32 months after the fire. Fungal CFUs were more sensitive to the fire and recovered more slowly than bacteria. Fungi recovering less rapidly than bacteria were also indicated by the PLFA pattern, with PLFAs indicative of fungi being less common after the fire. The recovery of microbial biomass and activity was mirrored by the initially very high levels of dissolved organic carbon being consumed and decreasing within 8 months after the fire. The wildfire event had thus resulted in a decrease in microbial biomass, with a more bacteria-dominated microbial community.  相似文献   

7.
Though it is undoubted that tropical bees are influenced by habitat composition, few studies have investigated the relative importance of both local and landscape-level habitat parameters in supporting large and diverse bee communities. The conservation of native bee communities within agroforestry landscapes is particularly urgent given the importance of pollination services within these systems. In this study, we examined tropical bee communities within a largely deforested shade coffee-growing region in Chiapas, Mexico. We used regression tree modeling to examine the response of bee functional groups to local and landscape-level habitat management. Our models revealed that the most predictive factors for bee abundance and species richness were the number of tree species, the number of tree species in flower, and the canopy cover of the local agroforestry landscape. Solitary bees were most abundant in habitats with high canopy cover, while social bees were most abundant in habitats with greater tree species richness. Cavity-nesting and wood-nesting bee abundance was positively affected by the amount of canopy cover in the farm, while ground-nesting bees were most abundant in habitats with a large number of tree species in flower. Our results demonstrate that across bee sociality groups, nesting guilds, and tribes, the most critical factor impacting native bee communities was within-farm local vegetation management. These results reveal the important role that agroforestry managers can have on biodiversity conservation, and the potential contribution they can make by creating resource-rich agricultural matrices. Specifically, our findings highlight the importance of diverse overstory tree management in supporting native bee communities within tropical agroforestry systems.  相似文献   

8.
The study intended to compare repellency of three insecticides on bumble bees and honey bees in Norwegian red clover (Trifolium pratense L.) seed crops, and to examine effects of thiacloprid on bumble bee colony development in the field. The repellency study was carried out in a large-scale field trial in SE Norway in 2013. On average for observations during the first week after spraying, 17 and 40% less honey bees (P?=?.03) and 26 and 20% less bumble bees (P?=?.36) were observed on plots sprayed with the pyrethroids lambda-cyhalothrin and alpha-cypermethrin, respectively, than on unsprayed control plots. No pollinator repellency was found on plots sprayed with the neonicotinoid thiacloprid. Compared with unsprayed control the seed yield increases were 22% on plots sprayed with thiacloprid vs. 12–13% on plots sprayed with pyrethroids (P?=?.10). Follow-up studies in 2014–2016 focused on the effect of thiacloprid on bumble bee colony development in commercially reared nests of Bombus terrestris placed into red clover seed crops at the start of flowering. Unsprayed control crops were compared with crops sprayed either at the bud stage or when 18–44% of flower heads were in full bloom. Chemical analyses of adult bumble bees showed that thiacloprid was taken up in bees when crops were sprayed during flowering, but not detected when crops were sprayed at the bud stage. The bumble bees in late-sprayed crops also developed weaker colonies than in unsprayed crops. Dead bees with a high internal concentration of thiacloprid were found in one crop sprayed during the night at 35% flowering. This shows that thiacloprid is not bee-safe if sprayed after anthesis and that spraying has to be conducted at the bud stage to reduce its contamination of nectar and pollen.  相似文献   

9.
The effect of wildfire and the subsequent harvesting on soil degradation was evaluated in a burned Pinus pinaster stand in Galicia (NW Spain). During the first year following a fire of moderate intensity, burned trees were not harvested and soil erosion losses, measured by sediment collection at the bottom of bordered plots, were very low. An apparently limited impact of fire on soil and reduced rainfall erosivity for this period could be responsible for that result. Salvage logging took place 13 months after fire. Three post‐fire alternatives were compared: no harvesting (standing burned trees), harvesting + windrowed slash and harvesting + slash chopping. Soil losses were even lower during the 14 months after these treatments than for the previous pre‐harvesting period. Again, low mineral soil exposition and rainfall erosivity seemed to contribute to that result. Changes in soil bulk density and soil shear strength after clearcutting and slash manipulation were small and not enough to trigger sediment yield significantly. Harvesting and logging operations apparently increased soil inhomogeneities. This degree of variability was more adequately assessed by using micro‐plot fences instead of plot fences. The percentage of soil disturbed by machinery was the variable most related with the observed minor soil losses after harvesting, at micro‐plot level. This study indicated that the combined effect of wildfire and clearcutting caused only an acceleration of soil erosion when significant exposition of mineral soil occurred after these perturbations. However, these results must be taken with caution because rain erosivity during the study was low. To delay post‐fire clearcutting until several months after the fire could reduce the impact of this forestry operation on burned soils, taking advantage of the natural mulch created by scorched leaves fall, although other issues must be taken into account. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

10.
Marginal habitats such as hedgerows or roadsides become especially important for the conservation of biodiversity in highly modified landscapes. With concerns of a global pollination crisis, there is a need for improving pollinator habitat. Roadsides restored to native prairie vegetation may provide valuable habitat to bees, the most important group of pollinators. Such roadsides support a variety of pollen and nectar sources and unlike agricultural fields, are unplowed, and therefore can provide potential nesting sites for ground-nesting bees. To examine potential effects of roadside restoration, bee communities were sampled via aerial netting and pan trapping along roadside prairie restorations as well as roadsides dominated by non-native plants. Management of roadside vegetation via the planting of native species profoundly affected bee communities. Restored roadsides supported significantly greater bee abundances as well as higher species richness compared to weedy roadsides. Floral species richness, floral abundance, and percentage of bare ground were the factors that led to greater bee abundance and bee species richness along restored roadsides. Traffic and width of roadside did not significantly influence bees, suggesting that even relatively narrow verges near heavy traffic could provide valuable habitat to bees. Restored and weedy roadside bee communities were similar to the prairie remnant, but the prairie remnant was more similar in bee richness and abundance to restored roadsides. Restoring additional roadsides to native vegetation could benefit pollinator conservation efforts by improving habitat on the millions of acres of land devoted to roadsides worldwide, land that is already set aside from further development.  相似文献   

11.
Declines in many bumble bee species have been documented in Europe raising several ecological and economic concerns. The nature and extent of bumble bee decline in North America is poorly understood due mainly to a lack of baseline and long-term data. Museum collections provide excellent sources of information on past and current species distributions, which can be used to infer changes in the composition of insect communities. Using the Illinois Natural History Survey’s electronic database of Hymenoptera and a recent biodiversity survey of historically sampled localities, we were able to examine changes in the richness and distribution of the bumble bee fauna of Illinois over the last century. We found that bumble bee species richness declined substantially during the middle of the century (1940-1960). Four species were locally extirpated: Bombus borealis, Bombus ternarius, Bombus terricola and Bombus variabilis. The ranges of Bombus affinis, Bombus fraternus, Bombus pensylvanicus and Bombus vagans have also decreased in Illinois. Our analyses also indicated that current bumble bee diversity is highest in northern Illinois, where conservation efforts would be most productive. Our study demonstrates that half of the bumble bee species found historically in Illinois have been locally extirpated or have suffered declines, supporting observations of broader declines in North America. Major declines in the bumble bee fauna coincided with large-scale agricultural intensification in Illinois between 1940 and 1960. Attempts to conserve bumble bees in Illinois should involve wildlife-friendly approaches to agriculture, such as increasing agricultural land set-asides and hedgerows, and employing integrated pest management.  相似文献   

12.
The importance of bioturbation as an agent of soil and geomorphological change is well known but few observations have been made of spatial and temporal variations in bioturbation rates. We quantified variations in surface bioturbation by ants (particularly Aphaenogaster longiceps) and vertebrates in the sandstone terrain of the Blue Mountains, southeast Australia. Following wildfire during the period late 2001–early 2002, we monitored thirty-three 5 m2 plots positioned in six different slope units and in two catchments affected by different wildfire severities. Measurements were made seasonally for six years. Overall, mean rates of ant mounding and surface scraping by vertebrates were similar (246 ± 339 g m− 2 yr− 1 and 274 ± 179 g m− 2 yr− 1, respectively). However, rates varied substantially according to slope unit, showing a marked maximum for both ant mounding and total bioturbation on footslopes. Possible reasons for this spatial variation are discussed. A complex response to various soil and ecological factors such as soil texture, soil moisture and vegetation patterns is the most likely explanation. Associated estimates of topsoil (0–30 cm depth) turnover times, based on ant mounding rates alone, ranged from 300 to 100,000 years for different slope units. In contrast to previous findings, wildfire severity did not seem to affect bioturbation, possibly because of ant survival in deep nests and spatial patchiness of fire severity. There was likewise no clear link between temporal changes in bioturbation and fire severity; high rates in the first two years after wildfire were followed by lower rates for all burn severity types. There was also seasonal variability that was not directly related to rainfall. The results substantiate the importance of bioturbation in modifying soil characteristics and influencing soil erosion, especially following a major disturbance event like wildfire.  相似文献   

13.
The frequency and intensity of wildfires are expected to increase in the coming years due to the changing climate, particularly in areas of high net primary production. Wildfires represent severe perturbations to terrestrial ecosystems and may have lasting effects. The objective of this study was to characterize the impacts of wildfire on an ecologically and economically important ecosystem by linking soil properties to shifts in microbial community structure in organic horizon soils. The study was conducted after a severe wildfire burned over 7000 ha of the New Jersey Pinelands, a low nutrient system with a historical incidence of fires. Soil properties in burned and non-burned soils were measured periodically up to two years after the fire occurred, in conjunction with molecular analysis of the soil bacterial, fungal and archaeal communities to determine the extent and duration of the ecosystem responses. The results of our study indicate that the wildfire resulted in significant changes in the soil physical and chemical characteristics in the organic horizon, including declines in soil organic matter, moisture content and total Kjeldahl nitrogen. These changes persisted for up to 25 months post-fire and were linked to shifts in the composition of soil bacterial, fungal and archaeal communities in the organic horizon. Of particular interest is the fact that the bacterial, fungal and archaeal communities in the severely burned soils all changed most dramatically during the first year after fire, changed more slowly during the second year after the fire, and were still distinct from communities in the non-burned soils 25 months post-fire. This slow recovery in soil physical, chemical and biological properties could have long term consequences for the soil ecosystem. These results highlight the importance of relating the response of the soil microbial communities to changing soil properties after a naturally occurring wildfire.  相似文献   

14.
In this study, mineralization of digested pig slurry and compost from municipal organic wastes in burned soils was followed for 60 days. The effects of amendments on organic matter fractions and microbial community level physiological profiles (CLPP) were also investigated at the end of the incubation period. Soil from a forest 10 days after a fire had a greater basal respiration, and more organic matter that a nearby soil that was not affected by fire, presumably as a consequence of black ash addition following the wildfire. Nitrification was inhibited in soils treated at 105 and 250 °C in the laboratory, but amendment application allowed nitrification to take place in the latter soil, and led to significant flushes of mineralization. Slurry amendment resulted in greater increases in mineral N compared with compost. Soil treated at 250 °C had the greatest content of water-extractable compounds (WE) at the expense of acid-extractable compounds (AE), but during the incubation the variations in these two fractions had an opposite trend, i.e. soil gained AE and lost WE fractions. The variation in N-acetyl-glucosamine-induced respiration was different between compost- and slurry-amended soils, with the greater values in the former. The effect of amendments could be further differentiated by principal component (PCA) and cluster analyses based on the variations in organic matter fractions and CLPP between the beginning and the end of the incubation period. Amendment application led to shifts on the PCA maps that depended both on the amendment and soil treatment. In fresh soil and in that treated at 250 °C, the unamended, compost- and slurry-amended treatments remained relatively close on the PCA maps and had linkage distances <1.0. In contrast, amendment application to other soils led to large shifts on the PCA maps and to linkage distances >1.0. Pig slurry led to the greatest changes in burned soil, while compost induced the greatest shifts in soil treated at 105 °C.This study suggests that an application of organic amendments after a severe fire event may contribute to a faster recovery of soil functions.  相似文献   

15.
An understanding of soil thermal conductivity after a wildfire or controlled burn is important to land management and post-fire recovery efforts. Although soil thermal conductivity has been well studied for non-fire heated soils, comprehensive data that evaluate the long-term effect of extreme heating from a fire on the soil thermal conductivity are limited. The purpose of this study was to evaluate the long-term impact of fire on the effective thermal conductivity of soils by directly comparing fire-heated and no-fire control soils through a series of laboratory studies. The thermal conductivity was measured for ten soil samples from two sites within the Manitou Experimental Forest, Colorado, USA, for a range of water contents from saturation to the residual degree of saturation. The thermal conductivity measured was compared with independent estimates made using three empirical models from literature, including the Campbell et al.(1994), Cté and Konrad(2005), and Massman et al.(2008) models. Results demonstrate that for the test soils studied, the thermal conductivity of the fire-heated soils was slightly lower than that of the control soils for all observed water contents.Modeling results show that the Campbell et al.(1994) model gave the best agreement over the full range of water contents when proper fitting parameters were employed. Further studies are needed to evaluate the significance of including the influence of fire burn on the thermal properties of soils in modeling studies.  相似文献   

16.
Yvonne Elizabeth Martin   《CATENA》2007,69(3):206-219
An algorithm for wildfire occurrence is introduced for incorporation into a numerical model of drainage basin evolution. Within the model, fire return intervals are determined using a stochastic rule set and fire sizes are assigned according to a pareto distribution. A Weibull distribution was fit to millennial-scale lake charcoal data for calibration of fire return intervals in this study, while data for the Olympic Peninsula were used to determine the fire size distribution. Loss of tree root strength resulting from stand-replacing wildfires has been found to be comparable to loss after timber harvesting. Hence, data for increased shallow landslide activity associated with logging were used to calibrate transport equations for years following wildfire incidence. A weathering relation is incorporated in the model, which drives the supply of sediment. When sediment supply is depleted in the model, the shallow landsliding module shuts off until new material is available for transport. Time since last fire analysis indicates that the Weibull parameters defined for the Clayoquot charcoal data produce results that are weighted too heavily towards recent fires. Sensitivity analysis was undertaken, suggesting alternative values may be more reasonable for further model runs. The introduction of a weighted probability factor for aspect, whereby south-facing slopes have a higher likelihood of fire initiation, was not found to significantly affect patterns of fire age in the landscape. Patterns of net topographic change after 6000 years of model run time indicate that greatest net erosion is found on steep, upper slopes, with the highest deposition occurring in hillslope hollows and low-order channels. Depositional grid cells in interfluves show a variable response to the inclusion of wildfire in the model. Net erosion occurs over a relatively low proportion of hillslope area, with wildfire model runs showing a strong erosional signal in these locations. For stream grid cells, the additional deposition due to the inclusion of wildfire in model runs is about 9–10% for 1st to 3rd order streams. Overall, deposition rates increase with decreasing stream order, reflecting greater hillslope/channel coupling in low-order streams.  相似文献   

17.
Pollination has received attention recently due to reported sharp declines of Apis mellifera in several locations, and it has been proposed that diverse native bee communities may be key for continued pollination of economically important crops. However, there is some inconsistency in the literature as to how these communities should best be managed. To address this issue, we collected bees from an intensively managed agricultural region in eastern Australia using blue vane traps. Both linear remnants of vegetation, which form part of a larger corridor network, and adjacent fields of native and exotic pastures, wheat, canola, and lucerne were sampled. A total of 3249 individual bees, representing four families and 36 species were collected. Highly modified environments of nectar-bearing crop supported the most species-rich bee assemblages, and the highest abundance of individual bee species. Distance from the remnants did not limit the body size of species occupying fields (up to 400 m). However, richness of bee assemblages also responded positively to the presence of conservation land in nearby areas, or the number of remnant native trees surrounding traps. Linear remnants of native vegetation contributed to assemblage heterogeneity by adding unique species to the regional pool. Our findings indicate that agricultural industries that currently rely on pollination by A. mellifera should ensure that intensive land use is complemented by untilled areas in the form of conservation land, or farm dams and scattered trees in fields, to support wild pollinators that may act as insurance against further future losses of managed hives.  相似文献   

18.
The native bee fauna provides an important ecosystem function, but a large proportion of this fauna in Europe is threatened as a result of habitat loss and fragmentation. The solitary bee Andrena hattorfiana is specialised on collecting pollen from the plant-family Dipsacaceae. In northern Europe the major pollen resource is the insect-pollinated herb Knautia arvensis. We quantified the available K. arvensis resource, measured habitat characteristics and performed a flower-visitor survey in 57 well-defined K. arvensis populations in southern Sweden. There was a strong relationship between bee and plant population sizes. In populations with A. hattorfiana present (N = 26), the female bees utilised on average 39% (12-80%) of the total available pollen resource. The nest architecture and nesting biology of A. hattorfiana is described for the first time. By excavating nests, we found that the provisioning for one average bee nest (containing 6 cells) required ca. 72 inflorescences or 11 plant individuals. The results suggest a certain minimum pollen amount needed to host an A. hattorfiana population. For example, for a population of ten reproducing A. hattorfiana ♀ with the average degree of utilisation, the critical resource was predicted as 156 ± 16 individuals (±SE) of the plant K. arvensis, which corresponds to 780 inflorescences or 36,731,978 pollen grains. These findings suggest that calculations via a ‘pollen budget’ can predict critical resources for a given size of specialised bee population, and thereby provide a tool in conservation.  相似文献   

19.
Given that changes in the patterns of vegetation and size of carbon (C) pools in the Arctic are likely to be profound by the end of this century, it is necessary to characterise the identity and ecological groupings, in terms of temperature response and C substrate utilisation, of saprotrophic (decomposer) fungi in organic matter in Arctic soils. Thus, the aims of this study were: (1) to identify the fungi isolated from standing-dead material of Schistidium apocarpum, as an example of a High Arctic moss, (2) to determine mycelial extension rates of these fungi at a range of temperatures (4, 10 and 25 °C), and (3) to characterise the functional potential, defined by C substrate utilisation at 6 °C, of fungal taxa.Fungi were isolated at 4 °C from standing-dead material of S. apocarpum from an area of polar semi-desert (79 degrees N), close to Ny-Ålesund, Svalbard, in the High Arctic. From a collection of 662 isolates, 43 pure cultures were identified by DNA extraction, amplification, and sequencing. Phoma sclerotioides, previously known as a temperate snow mould, was isolated most frequently. The ecology of fifteen fungal isolates was characterised in detail. In terms of temperature response, two groups were apparent, one of truly psychrophilic/psychrotrophic fungi and one of more mesophilic fungi which were generally less frequently isolated. In terms of carbon substrate utilisation in semi-defined solid media, most fungi could utilise a variety of carbon substrates (degradation of casein, cellulose and starch was widespread), except for tannic acid (degraded by only two of the five P. sclerotioides isolates and Scytalidium lignicola) and lignin and chitin (not decomposed by any isolate). The majority of isolates had been recorded previously from polar environments and/or as being able to survive at low temperatures.Fungi in tundra ecosystems, therefore, have significant potential to mineralise C at temperatures below 10 °C. A better understanding of the ecology of these fungi will allow us to improve predictions of C dynamics in arctic biomes in the future.  相似文献   

20.
ABSTRACT

This article briefs agricultural librarians on three key aspects of Colony Collapse Disorder (CCD), a disease involving the virtually total disappearance and presumed annihilation of the adult bee population of hives: (1) the yearly multibillion dollar importance of honeybees as the nation's key crop pollinators and the annual $200 million domestic production and export of honey; (2) the more common bee diseases and well-known hive stressors that current theories of CCD suggest interact with each other in some as yet undetermined combination, perhaps including new pathogens to which most American bees have limited or no immunity; and (3) several bees other than the honeybee that are not currently affected by CCD and that have some potential as partial substitute pollinators for some crops.  相似文献   

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