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1.
Mosses are a dominant component of high-arctic terrestrial ecosystems, yet little is known regarding the abundance and diversity of fungi associated with these abundant plants. We investigated vertical patterns of abundance and diversity of fungi and their relationship with chemical properties within profiles of Hylocomium splendens and Racomitrium lanuginosum collected in the Oobloyah Bay area on Ellesmere Island, Canada. The moss profiles were divided into 6 (H. splendens) and 5 (R. lanuginosum) layers according to the color and texture, and hyphal length, fungal assemblages, and contents of organic chemical components (acid-unhydrolyzable residues, total carbohydrates, extractives) and nutrients (N, P, K, Ca, Mg) were measured. Total hyphal length was greatest at the middle layers of H. splendens and at the deepest layers of R. lanuginosum and was significantly affected by moss species and nutrient contents. A total of 18 and 19 fungal taxa was isolated from the profiles of H. splendens and R. lanuginosum, respectively, with 11 taxa being common to both moss species. Moss species significantly affected the species distribution of fungi. Individual fungal taxa showed patterns of vertical distribution within the moss profiles. The contents of acid-unhydrolyzable residues and nutrients increased and the content of total carbohydrates decreased down the profile, which was attributable to the ability of fungi to decompose carbohydrates selectively and to immobilize nutrients in decomposed moss residues.  相似文献   

2.
Arbuscular mycorrhizal fungi (AMF) play important roles in ecosystem processes. However, little is known about AMF abundance in arid, nutrient-poor environments like the Mojave Desert of North America. We conducted two AMF studies: one examined AMF responses to elevated atmospheric CO2 at the Nevada Desert FACE (Free-Air-Carbon dioxide-Enrichment) Facility (NDFF), and the second examined seasonal dynamics at nearby sites. In both studies, AMF measurements (root colonization, extra-radical hyphal [ERH] length, and two measures of glomalin-related soil protein [GRSP]) and environmental factors (root length, soil water content, and precipitation) were measured across microsites (beneath shrubs, shrub interspaces) for two species (Larrea tridentata, Ambrosia dumosa). Elevated CO2 did not significantly affect AMF measurements. Other NDFF studies show no change in fine root production under elevated CO2 but show increased available nitrogen. We infer that additional fixed carbon under elevated CO2 is not allocated to soil resource foraging. However, AMF varied seasonally. ERH seasonally declined across species and microsites, but GRSP declined only beneath L. tridentata. Our results combined with previous results indicate that drought negatively affects AMF root colonization. Robust inter-relationship among AMF measurements only occurred between the two measures of GRSP, indicating that resources are independently allocated to different AMF structures.  相似文献   

3.
In this study, a systematic survey of cultural airborne fungi was carried out in the occurrence environments of wall paintings that are preserved in the Tiantishan Grottoes and the Western Xia Museum, China. A bio-aerosol sampler was used for sampling in four seasons in 2016. Culture-dependent and -independent methods were taken to acquire airborne fungal concentration and purified strains; by the extraction of genomic DNA, amplification of fungal ITS rRNA gene region, sequencing, and phylogenetic analysis, thereafter the fungal community composition and distribution characteristics of different study sites were clarified. We disclosure the main environmental factors which may be responsible for dynamic changes of airborne fungi at the sampling sites. The concentration of cultural airborne fungi was in a range from 13 to 1,576 CFU/m3, no significant difference between the two sites at the Tiantishan Grottoes, with obvious characteristics of seasonal variation, in winter and spring were higher than in summer and autumn. Also, there was a significant difference in fungal concentration between the inside and outside of the Western Xia Museum, the outside of the museum was far more than the inside of the museum in the four seasons, particularly in the winter. Eight fungal genera were detected, including Cladosporium, Penicillium, Alternaria, and Filobasidium as the dominant groups. The airborne fungal community structures of the Tiantishan Grottoes show a distinct characteristic of seasonal variation and spatial distribution. Relative humidity, temperature and seasonal rainfall influence airborne fungal distribution. Some of the isolated strains have the potential to cause biodeterioration of ancient wall paintings. This study provides supporting information for the pre-warning conservation of cultural relics that are preserved at local sites and inside museums.  相似文献   

4.
This article presents a summary of our studies of Holocene moraines and glaciers of the Tien-Shan, Pamir, and Himalaya mountains with the purpose of providing pattern regularity of the Holocene glaciation decomposition. We developed a method for obtaining reliable radiocarbon dating of moraines with the use of autochthonous organic matter dispersed in fine-grained morainic material, as well there were shown new possibilities of isotope-oxygen and isotope-uranium analysis for the Holocene glaciations dynamics. We found that Holocene glaciations disintegrate stadially according to the decaying principle, and seven main stages may be distinguished. We achieved the absolute dating of the first three stages, identifying these periods as 8,000, 5,000, and 3,400 years ago. The application of the above-mentioned isotope methods of the Holocene glaciations and moraines study will allow researchers to improve the offered model of the Holocene glaciations disintegration; it will be great contribution to salvation of the problem of long-term climatic and glaciations forecast.  相似文献   

5.
In Alaska, lichenometry continues to be an important technique for dating late Holocene moraines. Research completed during the 1970s through the early 1990s developed lichen dating curves for five regions in the Arctic and subarctic mountain ranges beyond altitudinal and latitudinal treelines. Although these dating curves are still in use across Alaska, little progress has been made in the past decade in updating or extending them or in developing new curves. Comparison of results from recent moraine-dating studies based on these five lichen dating curves with tree-ring based glacier histories from southern Alaska shows generally good agreement, albeit with greater scatter in the lichen-based ages. Cosmogenic surface-exposure dating of Holocene moraines has the potential to test some of the assumptions of the lichenometric technique and to facilitate the development of a new set of improved lichen dating curves for Alaska.  相似文献   

6.
Erosion and sediment transport in High Arctic rivers, Svalbard   总被引：2，自引：0，他引：2  
This paper discusses sediment yield, sediment delivery and processes of erosion in rivers subject to High Arctic conditions in Svalbard. Long-term measurements reveal large variations between rivers and from year to year in each individual river. In the unglacierized catchment of Londonelva, annual sediment transport varied between 28 and 93 t/yr, with a mean sediment yield of 82.5 t/km2/yr. In the glacier-fed rivers Bayelva and Endalselva, the suspended sediment transport varied in the range of 5126 t/yr to 22797 t/yr during a 12-year period. A mean of 11 104 t/yr gave rise to a mean sediment yield of 359 t/km2/yr for the whole Bayelva catchment area. The sediment yield of the glacier and the moraine area was estimated at 586 t/km2/yr. A conceptual model used to interpret the long- and short-term patterns of sediment concentration in the meltwater from the glacier and erosion of the neoglacial moraines is proposed. Evidence is found that a proportion of the sediments are delivered by a network of englacial and subglacial channels that exist even in cold ice. Regression analyses of water discharge versus suspended sediment concentration gave significant correlations found to be associated with the stability of ice tunnels in cold ice. Large floods have been found to flush the waterways and exhaust the sediment sources. A long-term change in the exponent of regression lines is attributed to changes in sediment availability caused by flushing and expansion of tunnels and waterways by large floods and a subsequent slow deformation of them caused by the ice overburden and the glacier movement. A comparison of sediment yields from a number of polythermal and temperate glaciers in various areas showed large differences that were attributed primarily to bedrock susceptibility to erosion and, secondarily, to glaciological parameters.  相似文献   

7.
通过选取阿拉善地区3个典型霸王群落为研究对象,研究霸王器官间(根、茎、叶)生态化学计量比特征及非结构性碳水化合物(Non-structural carbohydrates,NSCs)的变化,以便加深对霸王生存策略的理解,更好的服务于荒漠生态系统的生态恢复。结果表明:霸王茎和叶中可溶性糖(Solu?ble sugar,SS)、淀粉(Starch,ST)和NSCs含量随干旱加剧均显著降低。根系中SS和NSCs在3个样点间差异不显著,ST先降低后增加,ST含量在Plot3中比在Plot1和Plot2中高19.3%和31.2%。干旱使霸王根、茎、叶中N、P含量显著下降,使根、茎、叶中C:N和C:P显著增高,叶片N:P<14。Plot1中霸王器官间SS、SS:ST和NSCs含量表现为叶片>根>茎,ST含量为茎>根>叶片;Plot2和Plot3中霸王器官间SS、ST和NSCs含量均为根>茎>叶片。3个样点中叶片相较于茎干和根系具有高的N、P含量和低的C:N和C:P。NSCs与C:N:P间的关系表明:根、茎、叶中的N含量与SS正相关,叶片N含量与根系ST负相关。以上结果表明霸王的茎干和根系可能扮演“营养库”的角色,霸王通过提高N、P利用效率来减缓水分亏缺使其生长受到N限制的影响。霸王通过调节器官间NSCs的积累及分配来适应干旱,采取将根系中ST转化为SS来调节渗透势的策略;并随干旱加剧将更多的碳水化合物投资分配到根部,以ST的形式存储,而N是影响霸王根系中ST与SS间转化和ST存储的关键元素。  相似文献   

8.
In arid and semi-arid environments, root-associated fungi may play a key role in plant communities (e.g., seedling establishment, nutrient acquisition, plant survival and heat tolerance). Several studies have shown the importance of small mammals as consumers and dispersal agents of mycorrhizal fungi spores in tropical and temperate ecosystems. However, little is known about the dispersal of infective propagules of endophytic fungi in arid and semi-arid ecosystems. This study analyzed the potential role of the subterranean rodent Ctenomys cf. knighti as a dispersal agent of root-associated fungi. In order to demonstrate this role, we analyzed: (1) the incidence of colonization of arbuscular mycorrhizae and dark septate endophytes on representative plant species of the Monte Desert; (2) the presence of fungal structures of arbuscular mycorrhizae and dark septate endophytes in C. cf. knighti fecal samples; and (3) the infectivity of the fungal propagules contained in the scat and their growth effects on nine native plant species. Data strongly suggest that this South American subterranean rodent may play a key role as a dispersal agent of arbuscular mycorrhizae and dark septate endophytes fungi in the arid environment of the northern Monte Desert of Argentina.  相似文献   

9.
The Aragón Valley glacier (Central Western Pyrenees) has been studied since the late nineteenth century and has become one of the best areas in the Pyrenees to study the occurrence of Pleistocene glaciations and the relationships between moraines and fluvial terraces. New morphological studies and absolute ages for moraines and fluvial terraces in the Aragón Valley allow a correlation with other Pyrenean glaciers and provide solid chronologies about the asynchroneity between global last glacial maximum (LGM) and the maximum ice extent (MIE). Six frontal arcs and three lateral morainic ridges were identified in the Villanúa basin terminal glacial complex. The main moraines (M1 and M2) correspond to two glacial stages (oxygen isotopic stages MIS 6 and MIS 4), dated at 171 ± 22 ka and 68 ± 7 ka, respectively. From a topographical point of view, moraine M1 appears to be linked to the 60 m fluvioglacial terrace, dated in a tributary of the Aragón River at 263 ± 21 ka. The difference in age between M1 moraine and the 60 m fluvioglacial terrace suggests that the latter belongs to an earlier glacial stage (MIS 8). Moraine M2 was clearly linked to the fluvioglacial 20 m terrace. Other minor internal moraines were related to the 7–8 m terrace. The dates obtained for the last glacial cycle (20–18 ka) are similar to other chronologies for Mediterranean mountains, and confirm the occurrence of an early MIE in the Central Pyrenees that does not coincide with the global LGM.  相似文献   

10.
The genus Tritaenia with its type species T. linkii Magdefrau et Rudolph emend, from the Wealden of Germany has been referred to the family Miroviaceae Bose et Manum, comprising Mesozoic and mostly Arctic conifer foliage with 'Sciadopitys-like' stomatal distribution. Two other additions to the Miroviaceae, both from the Lower Cretaceous of West Greenland, arc Pityophyllum crassum Seward, now attributed to Tritaenia , and Mirovia groenlandica n. sp., described on leafy stems and detached leaves. Tritaenia has distinct stomatal bands within the median stomatal zone. This and other stomatal distributions in the Miroviaceae and their implications for the interpretation of leaf venation are discussed with the conclusion that two veins are most likely indicated. Diagnostic characters and stratigraphic and geographic distribution of the presently known miroviaceous taxa are summarized.  相似文献   

11.
Relict marginal moraines are commonly used landforms in palaeoglaciological reconstructions. In the Swedish mountains, a large number of relict marginal moraines of variable morphology and origin occur. In this study, we have mapped 234 relict marginal moraines distributed all along the Swedish mountains and classified them into four morphological classes: cirque‐and‐valley moraines, valley‐side moraines, complex moraines and cross‐valley moraines. Of these, 46 moraines have been reclassified or are here mapped for the first time. A vast majority of the relict moraines are shown to have formed during deglaciation of an ice‐sheet, rather than by local mountain glaciers as suggested in earlier studies. The relict marginal moraines generally indicate that deglaciation throughout the mountains was characterised by a retreating ice‐sheet, successively damming glacial lakes, and downwasting around mountains. The general lack of moraines indicating valley and cirque glaciers during deglaciation suggests that climatic conditions were unfavourable for local glaciation during the last phase of the Weichselian. This interpretation contrasts with some earlier studies that have reconstructed the formation of local glaciers in the higher parts of the Swedish mountains during deglaciation.  相似文献   

12.
The retreat record of the Stabre Glacier into the Norra Storfjället mountains, after separation from the massive Tärnaån Glacier at some undetermined time in the Atlantic Chron, is documented by recessional moraines in the foreland. While poorly constrained by radiometric dating, the age of the middle group of moraines averages out to less than 4000 cal 14C yr BP, the older moraine group probably of Late Atlantic age, with the youngest deposits of Little Ice Age (LIA). Soils/paleosols range from Entisols (youngest) and Inceptisols (middle group) to mature Spodosols (outer group), existing either as single‐story profiles or within pedostratigraphic columns, buried pedons either surfaced with weathered glacial or mass wasted deposits. Some profiles exhibit convoluted properties which could place them in the Cryosolic order. The physico‐mineral‐chemical properties of soils/paleosols in recessional deposits across this sequence provide weathering indices over the mid to Late Holocene in the Swedish sub‐Arctic climate. It is likely the middle group of deposits represents stillstand of the retreating glacier offset by climatic deterioration with the onset of Early Neoglacial climate which altered the glacial mass balance, at least until termination of the LIA. Correlation to other alpine areas in the middle and tropical latitudes with similar records is attempted and discussed. While the Stabre Glacier disappeared after the LIA, the nearby Tärna Glacier remains extant on the land surface, a presumed result of slight elevation differences between the two cirques which affects storm tracks and resultant variations in glacial mass balances.  相似文献   

13.
Benthic diatoms are commonly used for palaeoenvironmental reconstruction in Arctic regions, but interpretation of their ecology remains challenging. We studied epilithic diatom assemblages from the shallow margins of 19 lakes from three areas (coast-inland-ice sheet margin) along a climate gradient in Kangerlussuaq, West Greenland during two periods; shortly after ice-off (spring) and in the middle of the growth season (summer). We aimed to understand the distribution of Arctic epilithic diatoms in relation to water chemistry gradients during the two seasons, to investigate their incorporation into lake sediments and to assess their applicability as palaeoenvironmental indicators. Diatoms were correlated with nutrients in the spring and alkalinity/major ions in the summer, when nutrients were depleted; approximately half of the variance explained was independent of spatial factors. When categorised by functional attributes, diatom seasonal succession differed among regions with the most obvious changes in inland lakes where summer temperatures are warmer, organic nutrient processing is prevalent and silicate is limiting. These conditions led to small, motile and adnate diatoms being abundant in inland lakes during the summer (Nitzschia spp., Encyonopsis microcephala), as these functional attributes are suited to living within complex mats of non-siliceous microbial biofilms. Seasonal succession in silica-rich lakes at the coast was less pronounced and assemblages included Tabellaria flocculosa (indicating more acidic conditions) and Hannaea arcus (indicating input from inflowing rivers). The nitrogen-fixing diatom Epithemia sorex increased from the coast to the ice sheet, negatively correlating with a gradient of reactive nitrogen. The presence of this diatom in Holocene sediment records alongside cyanobacterial carotenoids during arid periods of low nitrogen delivery, suggests that it is a useful indicator of nitrogen limitation. Nitzschia species appear to be associated with high concentrations of organic carbon and heterotrophy, but their poor representation in West Greenland lake sediments due to taphonomic processes limits their palaeoenvironmental application in this region. Proportions of epilithic taxa in lake sediment records of coastal lakes increased during some wetter periods of the Holocene, suggesting that snowpack-derived nutrient delivery may offer diatom taxa living at lake margins a competitive advantage over planktonic diatoms during the “moating” ice melt period. Thus, further research investigating linkages between epilithic diatoms, snowpack and nutrient delivery in seasonally frozen lakes is recommended as these taxa live on the ‘front-line’ during the spring and may be especially sensitive to changes in snowmelt conditions.  相似文献   

14.
Dry conditions limit microbial decomposition of plant litter in deserts, which leaves a primary role to detritivorous macroarthropods. In the sandy arid strip along the west coast of South Africa, such detritivores include the large scarabaeid dung beetle Pachysoma glentoni. Highly unusual among dung beetles, this species collects surface litter and drags it into an underground storage and feeding chamber which is abandoned after 6–7 days. Fresh stores for single beetles and for breeding pairs (mean depths: 30 and 39 cm) contained about 1.1 and 2.9 g organic matter, respectively. Using ergosterol as a biomarker for fungal biomass, we tested the hypotheses that (1) the dry detritus takes up water underground; (2) this promotes fungal growth on the detritus, and (3) fungi are the main food of the beetles. These hypotheses were disproved, but the stored litter, including floral remains, was shown to have relatively high quality (mean atomic C:N ratio: 35) and the beetles assimilated about 60% of it. Estimated weekly water gain per beetle, supplied entirely by the food, was about 0.6 g. Our results highlight unique nutritional adaptations to survival in deserts without the usual dung beetle food: wet dung of large herbivores.  相似文献   

15.
为开展新奥尔松地区苔原植物生长和植被演替对冰川退缩响应的研究,在Austre Lovénbreen冰川(简称A冰川)前沿不同年代冰缘线附近布设了植被样方,调查了样方内植物组成与群落结构。结果表明:(1)A冰川1990年冰缘线代表植被演替的初始阶段,样方内仅出现先锋植物挪威虎耳草(Saxifraga oppositifolia);(2)1936年冰缘线代表冰川退缩长达75年后植被发育的情况,样方内植物种类和个体数明显增多,植被群落以木本植物极柳(Salix polaris)和草本植物黄葶苈(Draba bellii)为主,地衣以寒生肉疣衣(Ochrolechia frigida)和鸡皮衣(Pertusaria sp.)等壳状地衣为主;(3)随着冰川迹地形成时间更长,植被趋向成熟阶段发展,样方内极柳占绝对优势,地衣的物种多样性和盖度显著增加,出现雪黄岛衣(Flavocetraria nivalis)和刺岛衣(Cetraria aculeata)等叶状地衣。初步结果表明冰川退缩迹地上的物种更替明显,群落结构发生着显著变化。  相似文献   

16.
Community composition of arbuscular mycorrhizal (AM) fungi was analyzed in the roots of five representative shrub species (Genista cinerea, Lavandula latifolia, Rosmarinus officinalis, Thymus mastichina and Thymus zygis) growing in a typical semi-arid Mediterranean ecosystem. Roots from a well-preserved area of the ecosystem were extracted from soil and analyzed by nested PCR, single strand conformation polymorphism and sequencing of the NS31-AM1 and NS8-ARCH1311 regions of the small subunit of the ribosomal DNA (SSU rDNA). Ten AM fungal phylotypes were identified; eight belonged to the Glomeraceae and two to the Diversisporaceae. Only two of the phylotypes clustered with sequences of morphologically defined species and a high dominance by one AM group (Glomus intraradices) was detected. Our diversity analyses revealed that the AM fungal communities of G. cinerea, L. latifolia and T. mastichina did not significantly differ while the AM fungal communities of R. officinalis and T. zygis were distant from this cluster and from each other. The highest diversity was found in the roots of T. zygis. Our data indicate that co-occurring plant species may house distinct communities of AM fungi.  相似文献   

17.
In many areas of Svalbard, the Neoglacial terminal deposits represent the Holocene glacial maximum. The glaciers began the retreat from their Neoglacial maximum positions around 1900 AD. Based on high resolution acoustic data and sediment cores, sedimentation patterns in four tidewater glacier-influenced inlets of the fjord Isfjorden (Tempelfjorden, Billefjorden, Yoldiabukta and Borebukta), Spitsbergen, were investigated. A model for sedimentation of tidewater glaciers in these High Arctic environments is proposed. Glacigenic deposits occur in proximal and distal basins. The proximal basins comprise morainal ridges and hummocky moraines, bounded by terminal moraines marking the maximum Neoglacial ice extent. The distal basins are characterized by debris lobes and draping stratified glacimarine sediments beyond, and to some extent beneath and above, the lobes. The debris lobe in Tempelfjorden is composed of massive clayey silt with scattered clasts. Distal glacimarine sediments comprise stratified clayey silt with low ice-rafted debris (IRD) content. The average sedimentation rate for the glacimarine sediments in Tempelfjorden is 17 mm/yr for the last ca. 130 years. It is suggested that the stratified sediments in Tempelfjorden are glacimarine varves. The high sedimentation rate and low IRD content are explained by input from rivers, in addition to sedimentation from suspension of glacial meltwater. The debris lobes in Borebukta are composed of massive clayey silt with high clast content. Distal glacimarine sediments in Yoldiabukta comprise clayey silt with high IRD content. The average sedimentation rate for these sediments is 0.6 mm/yr for the last 2300 years.  相似文献   

18.
采用微生物宏基因组学微阵列GeoChip 5.0技术，选择腾格里沙漠东南缘沙坡头地区不同年代人工固沙植被区的生物土壤结皮（BSC）为对象，分析BSC演替过程中参与铁代谢的功能微生物组成及其功能基因变化特征，研究微生物铁代谢对BSC演替的响应及调控。结果表明：真菌参与铁吸收和转运过程，古菌参与铁转运和贮存过程，细菌则在铁代谢吸收、转运和贮存过程中均起主要调控作用。门水平上，BSC铁代谢功能微生物组成变化对演替的响应不敏感，BSC铁代谢微生物主要为变形菌门（Proteobacteria）。BSC铁代谢功能基因多样性的显著提高和三类铁代谢过程基因信号强度达到最高水平需要经过61 a的演替。调控BSC铁吸收过程的主要功能基因为亚铁氧化酶编码基因iro；调控原核生物铁转运过程的主要功能基因，为羟基苯甲酰丝氨酸铁外膜转运体编码基因cirA和Fe（Ⅱ）转运蛋白编码基因feoB，真菌铁转运过程主要依靠含铁细胞转运体和铁氧化酶高亲和力的作用；调控铁贮存过程的主要功能基因为固定相类核蛋白编码基因dps。在BSC演替阶段末期，上述铁代谢功能基因强度的显著增加促进了微生物的铁代谢潜能。干旱、半干旱荒漠生态系统植被恢复过程中微生物铁代谢潜能的恢复需要较长时间。  相似文献   

19.
The aim of this study is to extend our knowledge of the distribution of anisakid nematode parasites in Arctic and Antarctic polar regions. We examined vertebrate (fish) taxa characteristic of the faunas in both polar regions for the presence of parasitic nematodes. The material was collected from Svalbard (Arctic) between July and August 2008 and from King George Island (South Shetland Islands, Antarctic Peninsula) between November 2007 and January 2008. In addition, faecal, bird, and invertebrate samples were collected and examined for the presence of anisakid nematodes or eggs. Anisakis simplex s.s. was found in the body cavity of Arctic cod, and Contracaecum sp. and Pseudoterranova sp. were found in Antarctic notothenioids. Eggs of Anisakis sp. and Contracaecum sp. were recovered from the faeces of Mirounga leonina. We present the first record of the occurrence of A. simplex C in the Antarctic fishes Notothenia coriiceps and Notothenia rossii.  相似文献   

20.
It was hypothesized that litter with higher N concentration would decompose faster than that with lower N concentration and that increased soil nutrient availability would stimulate litter decomposition. To examine the interspecific differences in decomposition rate of leaf litter in relation with differences in litter chemistry and soil nutrient availability, senescent leaves of four species Pennisetum flaccidum, Artemisia scoparia, Chenopodium acuminatum and Cannabis sativa, and soil samples with different fertilization treatments (no fertilization, N, P, and N + P fertilizations, respectively) were collected from a sandy grassland in Northeast China and incubated under laboratory conditions. The decomposition rate of leaf litter was determined by measuring the CO2 emission during decomposition of litter. We found remarkable interspecific differences in leaf decomposition rates. Moreover, rates of litter decomposition at different incubation stages were correlated with different litter quality indices. The rate of litter decomposition was positively correlated with initial litter N concentration in the initial stage of the incubation, whereas it was negatively correlated with litter N and P concentrations in the late stage. Responses of litter decomposition to soil nutrient availability differed among species. Our results suggest that both indirect changes in litter quality through shifts of species composition/dominance and direct changes in soil nutrient availability under nutrient addition conditions could affect litter decomposition and consequently C and nutrient cycling of grassland ecosystems.  相似文献   

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