Effects of different components of diversity on productivity in artificial plant communities

In an experiment on artificial plant communities, the effects of three components of plant diversity—plant species diversity, plant functional group diversity and plant functional diversity—on community productivity and soil water content were compared. We found that simple regression analysis showed a positive diversity effect on ecosystem processes (productivity and soil water content). However, when three components of diversity were included in the multiple regression analyses, the results showed that functional group diversity and functional diversity had more important effects on productivity and resource use efficiency. These results suggested that, compared with species number, functional differences among species and the range of functional traits carried by plants are the basis of biodiversity effects on ecosystem functioning. These diversity effects of increasing functional group diversity or functional diversity were likely because species differing greatly in size, life form, phenology and capacity to capture and use resources efficiently in diverse communities realize complementary resource use in temporal, spatial, and biological ways.     

Circumpolar arctic tundra biomass and productivity dynamics in response to projected climate change and herbivory

Satellite remote sensing data have indicated a general ‘greening’ trend in the arctic tundra biome. However, the observed changes based on remote sensing are the result of multiple environmental drivers, and the effects of individual controls such as warming, herbivory, and other disturbances on changes in vegetation biomass, community structure, and ecosystem function remain unclear. We apply ArcVeg, an arctic tundra vegetation dynamics model, to estimate potential changes in vegetation biomass and net primary production (NPP) at the plant community and functional type levels. ArcVeg is driven by soil nitrogen output from the Terrestrial Ecosystem Model, existing densities of Rangifer populations, and projected summer temperature changes by the NCAR CCSM4.0 general circulation model across the Arctic. We quantified the changes in aboveground biomass and NPP resulting from (i) observed herbivory only; (ii) projected climate change only; and (iii) coupled effects of projected climate change and herbivory. We evaluated model outputs of the absolute and relative differences in biomass and NPP by country, bioclimate subzone, and floristic province. Estimated potential biomass increases resulting from temperature increase only are approximately 5% greater than the biomass modeled due to coupled warming and herbivory. Such potential increases are greater in areas currently occupied by large or dense Rangifer herds such as the Nenets‐occupied regions in Russia (27% greater vegetation increase without herbivores). In addition, herbivory modulates shifts in plant community structure caused by warming. Plant functional types such as shrubs and mosses were affected to a greater degree than other functional types by either warming or herbivory or coupled effects of the two.     

Improved water retention links high species richness with increased productivity in arctic tundra moss communities

A positive relationship between plant species richness and ecosystem functioning has been found in a number of experimental studies. Positive species interactions at high species numbers have been suggested as a cause, but mechanisms driving positive interactions have not often been tested. In this experiment we asked three questions: (1) What is the relationship between species richness and productivity in experimentally constructed moss communities? (2) Is this relationship affected by plant density? and (3) Can changes in moisture absorption and retention explain observed relationships? To answer these questions we exposed arctic tundra moss communities of different species richness levels (1–11 species) and two different densities in the greenhouse to two levels of drought (short and long). Biomass (by the community and individual species), height and community moisture absorption and retention were measured as response variables. High species diversity increased productivity (more so in low-density plots than in high-density plots), but only when plots were watered regularly. Plot moisture retention was improved at high species richness as well, and plant height and variation in height was increased compared to plants in monoculture. Under high-density and short-drought conditions 10 out of 12 species grew better in mixture than in monoculture, but under the long drought treatment only six species did. A positive feedback loop between biomass and improved humidity under high diversity was supported by path analysis. We conclude that in this community the relationship between species richness and productivity depends on moisture availability and density, with improved water absorption and retention likely to be the mechanism for increased plant growth when drought periods are short. Furthermore, since this is the opposite of what has been found for temperate moss communities, conclusions from one system cannot automatically be extrapolated to other systems.     

Interactive effects of herbivory and competition intensity determine invasive plant performance

Herbivory can reduce plant fitness, and its effects can be increased by competition. Though numerous studies have examined the joint effects of herbivores and competitors on plant performance, these interactive effects are seldom considered in the context of plant invasions. Here, we examined variation in plant performance within a competitive environment in response to both specialist and generalist herbivores using Chinese tallow as a model species. We combined tallow plants from native and invasive populations to form all possible pairwise combinations, and designated invasive populations as stronger neighbours and native populations as weaker neighbours. We found that when no herbivory was imposed, invasive populations always had higher total biomass than natives, regardless of their neighbours, which is consistent with our assumption of increased competitive ability. Defoliation by either generalist or specialist herbivores suppressed plant growth but the effects of specialists were generally stronger for invasive populations. Invasive populations had their lowest biomass when fed upon by specialists while simultaneously competing with stronger neighbours. The root/shoot ratios of invasive populations were lower than those of native populations under almost all conditions, and invasive plants were taller than native plants overall, especially when herbivores were present, suggesting that invasive populations may adopt an "aboveground first" strategy to cope with herbivory and competition. These results suggest that release from herbivores, especially specialists, improves an invader's performance and helps to increase its competitive ability. Therefore, increasing interspecific competition intensity by planting a stronger neighbour while simultaneously releasing a specialist herbivore may be an especially effective method of managing invasive plants.     

Effects of herbivory and competition on an introduced plant in decline

Anthemiscotula was introduced to Denmark 500 years ago, and its distribution is presently limited and in decline. A manipulative field experiment was performed to investigate the effects of native plant competitors and native invertebrate herbivores on its performance. Generally, both herbivory and competition treatments had great impact, and when both factors were operating, the effects were additive for all variables except plant height. Although A. cotula showed plasticity in growth, resource allocation and flowering timing, it was unable to adjust to competition and compensate for losses due to herbivory sufficiently to ensure and restore its achene production. This vulnerability, combined with improved cereal cleaning techniques and thus fewer reintroductions of A. cotula seeds, may be the cause of its current decline. A. cotula responded to herbivory by prolonging its flowering period, a “bet-hedging” strategy. In Denmark this strategy is unreliable since risks of sub-optimal conditions are much greater in August–October. Received: 12 December 1997 / Accepted: 14 October 1998     

Experimental comparison of competition and facilitation in alpine communities varying in productivity

Question. Competitive and facilitative interactions among plant species in different abiotic environments potentially link productivity, vegetation structure, species composition and functional diversity. We investigated these interactions among four alpine communities along an environmental productivity gradient in a generally harsh climate. We hypothesised that the importance of competition would be higher in more productive sites. Location. Mt. M. Khatipara (43°27′N, 41°41′E, altitude 2750 m), NW Caucasus, Russia. Communities ranged from low‐productivity alpine lichen heath (ALH) and snowbed communities (SBC), to intermediate productivity Festuca grassland (FVG), and high‐productivity Geranium‐Hedysarum meadow (GHM). Methods. We quantified the relative influence of competition and facilitation on community structure by expressing biomass of target species within each natural community proportionally to biomass of the species in a “null community” with experimental release from interspecific competition by removing all other species (for 6 years). An overall index of change in community composition due to interspecific interactions was calculated as the sum of absolute or proportional differences of the component species. Results. Species responses to neighbour removal ranged from positive to neutral. There was no evidence of facilitation among the selected dominant species. As expected, competition was generally most important in the most productive alpine community (GHM). The intermediate position for low‐productivity communities of stressful environments (ALH, SBC) and the last position of intermediately productive FVG were unexpected. Conclusions. Our results appear to support the Fretwell‐Oksanen hypothesis in that competition in communities of intermediate productivity was less intense than in low‐ or high‐productive communities. However, the zero net effect of competition and facilitation in FVG might be the result of abiotic stress due to strong sun exposure and high soil temperatures after neighbour removal. Thus, non‐linear relationships between soil fertility, productivity and different abiotic stresses may also determine the balance between competition and facilitation.     

Effects of competition and shading in planktonic communities

A model for several algal species which compete both for light and for nutrients, and which are also subject to settling and diffusion, is considered. The settling speeds and diffusion coefficients are assumed to be small, in a sense to be made precise later, and a singular perturbation argument is used. In certain cases vertical segregation of the algal species is observed, and the mechanism for this is interpreted biologically.Supported by the Danish Natural Science Research Council (Grant No. 11-8321)     

Neighbor effects on germination, survival, and growth in two arctic tundra plant communities

In relatively harsh environments such as arctic tundra, abiotic factors have traditionally been considered the primary determinants of community structure, overwhelming any effects of biotic interactions such as competition. Two common low arctic tundra types that differ in soil properties, moist acidic and moist non-acidic tussock tundra (MAT and MNT, respectively), occur in close proximity in northern Alaska. Several plant species occur in both communities with different relative abundance, while others are restricted to one. This study experimentally examined how neighboring vegetation affects germination, survival, and growth of species in these two communities that differ in soil pH, cation availability, and other characteristics. Germination of sown seeds was greater than background levels suggesting seed limitation may restrict recruitment of these clonal, perennial species. Germination of sown seeds was greater at both sites when both mosses and vascular plants had been removed compared to plots with intact vegetation. However, neighbors had almost no effect on survival and growth of adult transplants. Patterns of germination, survival and growth of several species differed depending on the community of origin and the community of destination of the seeds or transplanted adults. For example, transplants of the sedge Eriophorum vaginatum grew better if they were from MAT, and this species germinated better when sown at MNT. Although of relatively short duration (three growing seasons), this study suggests that biotic interactions may affect local species composition by restricting germination and establishment in these two communities, but have less of an effect on adult plants. Not surprisingly, site-specific abiotic conditions also exhibit control over species occurrence and relative abundance. Without disturbance to clear bare ground for recruitment of new individuals, these populations for the most part must rely on clonal growth to persist.     

Interactive effects of plant-available soil silicon and herbivory on competition between two grass species

Background and Aims

The herbivore defence system of true grasses (Poaceae) is predominantly based on silicon that is taken up from the soil and deposited in the leaves in the form of abrasive phytoliths. Silicon uptake mechanisms can be both passive and active, with the latter suggesting that there is an energetic cost to silicon uptake. This study assessed the effects of plant-available soil silicon and herbivory on the competitive interactions between the grasses Poa annua, a species that has previously been reported to accumulate only small amounts of silicon, and Lolium perenne, a high silicon accumulator.

Methods

Plants were grown in mono- and mixed cultures under greenhouse conditions. Plant-available soil silicon levels were manipulated by adding silicon to the soil in the form of sodium silicate. Subsets of mixed culture pots were exposed to above-ground herbivory by desert locusts (Schistocerca gregaria).

Key Results

In the absence of herbivory, silicon addition increased biomass of P. annua but decreased biomass of L. perenne. Silicon addition increased foliar silicon concentrations of both grass species >4-fold. Under low soil-silicon availability the herbivores removed more leaf biomass from L. perenne than from P. annua, whereas under high silicon availability the reverse was true. Consequently, herbivory shifted the competitive balance between the two grass species, with the outcome depending on the availability of soil silicon.

Conclusions

It is concluded that a complex interplay between herbivore abundance, growth–defence trade-offs and the availability of soil silicon in the grasses'' local environment affects the outcome of inter-specific competition, and so has the potential to impact on plant community structure.     

两种不同种植方式对龙葵叶片虫食状的影响研究

昆虫与植被之间相互关系的深入研究,有助于更好的理解生态系统结构与功能之间的关系以及生态系统生物多样性维持机理。本文通过对集中种植和分块种植下两种不同种植方式龙葵叶片虫食状进行调查分析,以期对龙葵的栽培和养护提供理论基础和技术建议。研究结果表明:龙葵叶片中共识别出11种虫食状类型,其中,集中种植方式有10种,分块种植方式有11种,各种虫食状类型出现频率在0.4%-24.7%;集中种植样地的龙葵叶片虫食状种类数、Shannon-Wiener指数和Pielou均匀度指数均低于分块种植;分块种植的龙葵叶片受到植食性昆虫的伤害频率较高,但是集中种植的龙葵叶片受到的伤害程度却明显高于分块种植方式。因此,种植龙葵应尽量避免大规模集中种植方式,不同生态系统边界之间边缘效应的尺度和强弱的关系是未来研究的重点和核心问题。     

Effects of pasture competition and specialist herbivory on the performance of Cirsium arvense

Combining specialist herbivory with interspecific plant competition can be an effective means of controlling pasture weeds. Cirsium arvense (Canada thistle, Californian thistle, creeping thistle) is one of the worst weeds of pastoral production systems in New Zealand (NZ). The oligophagous leaf-feeding beetle, Cassida rubiginosa, was recently released in NZ for control of C. arvense. To assess the impact of this biocontrol agent we conducted an outdoor potted-plant experiment with low and high densities of Cassida larvae combined with different levels of interspecific competition from typical NZ pasture species. Secondly, we carried out a field-release experiment to quantify the impact of high densities of Cassida under more natural conditions. Interspecific competition reduced all measured plant parameters of C. arvense except mean shoot height and base diameter. Herbivory by Cassida only reduced root biomass, and showed a weak additive response when combined with competition. All other measured parameters of C. arvense showed a substitutive response, with competition being the only factor having a significant impact on the weed. There were no significant synergistic interactions with competition and herbivory on C. arvense. Interestingly, the number of root buds per plant was significantly greater in the presence of herbivory by Cassida, suggesting that C. arvense may compensate for defoliation. Similar to the potted-plant experiment, Cassida had no significant effect on shoot growth and development in the field-release experiment. The results of this study indicate that competition from typical NZ pasture species is a more important factor than herbivory by Cassida, and unless Cassida reaches outbreak densities, it will likely have an insignificant impact on this weed.     

光能竞争对农林复合生态系统生产力的影响

农林复合生态系统是改善渭北黄土区脆弱生态环境、促进该区域经济发展的重要举措.以该区具有代表性的核桃(Juglans regia L.)、李子(Prunus salicina),绿豆(秦豆6号)、辣椒(陕椒981)农林复合模式为对象, 研究不同农林复合系统对光能分布、农作物生长、生产的影响.研究结果表明,不同复合模式下,玉米、辣椒的光合有效辐射、光合速率、生物量及产量均有不同程度的下降,且距树行愈近,影响愈大.叶片水势与玉米、辣椒的光合速率、地上部分生物量以及产量不相关或负相关.而10～20cm土壤含水量与绿豆的生物量和产量以及辣椒的地上部分生物量正相关.但绿豆、辣椒的生产量与其光合有效辐射呈显著正相关性,这说明,农林复合系统中光能竞争是导致间作绿豆、辣椒产量下降的主要原因.     

Structure of microbial communities of peat soils in two bogs in Siberian tundra and forest zones

The structure and functional activity of microbial complexes of a forest oligo-mesotrophic subshrub- grass-moss bog (OMB, Central Evenkiya) and a subshrub-sedge bog in the polygonal tundra (PB, Lena River Delta Samoylovsky Island) was studied. Soil of the forest bog (OMB) differed from that of the polygonal tundra bog (PB) in higher productivity (C_org, N_total, P, and K reserves), higher biomass of aerobic chemoorganotrophs (2.0 to 2.6 times), and twice the level of available organic matter. The contribution of microorganisms to the carbon pool was different, with the share of C_mic in C_org 1.4 to 2.5 times higher in PB compared to OMB. Qualitative composition of the methane cycle microorganisms in PB and OMB soils differed significantly. Methanogenic archaea (Euryarchaeota) in the shrub-sedge PB of tundra were more numerous and diverse than in the oligo-mesotrophic bog (OMB) and belonged to six families (Methanomassiliicoccaceae, Methanoregulaceae, Methanobacteriaceae, Methanomicrobiaceaee, Methanosarcinaceae, and Methanotrichaceae), while members of only four families (Methanosarcinacea, Methanobacteriaceae, Methanotrichaceae, and Methanomassiliicoccaceae) were revealed in OMB. In both bogs, methane-oxidizing bacteria belonged to Alphaproteobacteria (II) and Gammaproteobacteria (I). Methanotroph diversity was higher in OMB than in PB. Microbial communities of PB soils had higher potential activity of methanogenesis and methanotrophy compared to those of OMB. Methanogenic and methanotrophic activities in PB were 20 and 2.3 times higher, respectively, than in OMB.     

Effects of simulated herbivory in three old field Compositae with different inflorescence architectures

The effects of simulated herbivory (early or late defoliation and cutting of the flowering shoot) on the growth and reproduction of three species of monocarpic composite forbs (Crepis pulchra, Picris hieracioides and C. foetida) with different inflorescence architectures were studied in experimental plots. For the three species studied, early defoliation had no significant effect on subsequent growth. In contrast, late defoliation, occurring at the start of the season of drought, had a negative effect on growth and reproduction in the two Crepis species, particularly C. foetida, but had less effect on P. hieracioides. Sexual biomass was more clearly affected by late defoliation than was vegetative biomass, although the effects differed markedly among species possibly as a result of differences in phenology. Clipping the flowering shoot removed about 3 times less biomass than late defoliation and had little effect on vegetative biomass. It had much greater effects on the sexual biomass in P. hieracioides and C. pulchra, and resulted in the production of many shoots sprouting from the rosette, allowing the treated plants to regain a vegetative biomass close to that of control plants. Clipping did however lead to the production of shorter shoots and a reduction in the number of capitula formed. In C. foetida, much branching occurred even when the main shoot was not cut; the architecture of individual plants was therefore only slightly changed by clipping the apical bud and the sexual biomass of this species was not affected by ablation of the flowering shoot. Overcompensation was found in only two families of C. pulchra for vegetative biomass. No over-compensation was found for sexual biomass, despite an increase in the number of flowering shoots in C. pulchra and P. hieracioides following clipping. However situations close to compensation for the vegetative biomass in the three species and in P. hieracioides for the sexual biomass were recorded. The response of the three study species to simulated herbivory were related to their architecture and to the time of defoliation.     

Soil respiration of two dominant tundra communities under controlled temperatures in Changbai Mountain, Northeast China

Numerous seasonal snowpacks exist on alpine tundra of Changbai Mountain, Northeast China. The structure and species composition are distinct between snowpack and nonsnowpack communities, implying the difference in ecological processes in the subsurface. In order to clarify the relationship between soil respiration with thermal condition in snowpacks, as well as its seasonal variation, the respiration in response to temperature was measured based on simulated experiments. In addition to soil temperature, primary productivity was also investigated by harvesting the current-year aboveground growth. Field sampling was conducted in two community types: Rhododendron aureum community occurred in snowpack and Vaccinium uliginosum var. alpinum community (as reference) in snow-free area. An Li-8100 soil respiration system (Li-COR Co.) was used for measuring CO₂ release. Soil organic matter, total nitrogen and available nitrogen were analyzed. Hydrolizable nitrogen in Vaccinium community was 370–585 mg kg^?1, total nitrogen was 0.298%–0.468%, and organic matter was 13.5%–17.3%. In Rhododendron community, hydrolizable nitrogen was 445–583 mg kg^?1, total nitrogen was 0.465%–0.696%, and organic matter was 15%–22%. Organic matter within 10 cm depth was 4.07 kg m^?2 in Vaccinium community, and 5.31 kg m^?2 in the other. Temperature-dependent equations indicated that Q₁₀ values in both communities were around 2, with the ranges of 1.81–2.67 in Vaccinium community and 1.67–2.21 in Rhododendron community. The temperature-dependent equation was formed as y = ae^bx, where y is respiration rate (μmol kg^?1 h^?1), a and b are coefficients, and x is temperature in Celsius degree. Coefficient a was 52–148 in Vaccinium community and 34–167 in Rhododendron community, with significant variation among samples taken in different years. The daily respiration (g C kg^?1 d^?1) equation was y = 0.021733e^0.084063x for Vaccinium community, and y = 0.023482e^0.06x for Rhododendron community, both varied significantly with season. As to yearly respiration rate, it was 8.57–17.96 g C kg^?1 a^?1 in Vaccinium community, with a peak in May and relatively even in other time. The yearly respiration calculated by an integrated equation fitted with samples taken in all seasons was 10.24 g C kg^?1 a^?1. By covering Vaccinium community with a quilt in the field during the winter, soil temperature was slightly raised. During the frozen season, the temperature was raised by approximately 1.5 °C. Hence the annual respiration was 544.41 g C m^?2, 12 g C m^?2 higher than that of the reference. Respiration for Rhododendron community was in the range of 4.57–21.15 g C kg^?1 a^?1, with its maximum in May. By the integrated equation, it was 10.35 g C kg?1a^?1or 537 g C m^?2 a^?1. The yearly respiration was 441–544 g C m^?2 a^?1 in Vaccinium community and 449–486 g C m^?2 a^?1 in Rhododendron community. Taking the form of respiration on the basis of per kg of organic carbon, it was 118 g C (kg C)^{? 1} a^?1 in Vaccinium community and 101 g C (kg C)^{? 1} a^?1 in Rhododendron community. In particular, winter respiration in Vaccinium community was 2.10 g C kg?1, or 20.50% of yearly total, and merely 1.59% in the coldest month. While in Rhododendron community, it was 3.40 g C kg?1, or 32.84% of yearly total, significantly higher than that in Vaccinium community. The respiration in Rhododendron community at elevation 2260 m was 468.21 g C m^?2 a^?1, and the biomass growth was 400 g C m^?2 a^?1. In contrast, due to the thinner snow cover, in elevation 2036 m the biomass growth was 225.0 g C m^?2 a^?1 versus the respiration rate of 486.60 g C m^?2 a^?1. Leaf area index varied significantly in Rhododendron communities, ranging from 1.48 to 3.14, also owing to the difference in snow depth. As a contrary, in Vacciniumu community, the biomass growth was 120.75 g C m^?2 a^?1 and the leaf area index was 1.58. In conclusion, snowpacks provide a suitable condition for microbiomes in the winter, and contribute a large proportion of respiration. This also implies the vigorous activity in nitrogen release during the frozen season, which results in the rapid thriving of plants after snowmelt.     

Distinct microbial communities associated with buried soils in the Siberian tundra

Cryoturbation, the burial of topsoil material into deeper soil horizons by repeated freeze–thaw events, is an important storage mechanism for soil organic matter (SOM) in permafrost-affected soils. Besides abiotic conditions, microbial community structure and the accessibility of SOM to the decomposer community are hypothesized to control SOM decomposition and thus have a crucial role in SOM accumulation in buried soils. We surveyed the microbial community structure in cryoturbated soils from nine soil profiles in the northeastern Siberian tundra using high-throughput sequencing and quantification of bacterial, archaeal and fungal marker genes. We found that bacterial abundances in buried topsoils were as high as in unburied topsoils. In contrast, fungal abundances decreased with depth and were significantly lower in buried than in unburied topsoils resulting in remarkably low fungal to bacterial ratios in buried topsoils. Fungal community profiling revealed an associated decrease in presumably ectomycorrhizal (ECM) fungi. The abiotic conditions (low to subzero temperatures, anoxia) and the reduced abundance of fungi likely provide a niche for bacterial, facultative anaerobic decomposers of SOM such as members of the Actinobacteria, which were found in significantly higher relative abundances in buried than in unburied topsoils. Our study expands the knowledge on the microbial community structure in soils of Northern latitude permafrost regions, and attributes the delayed decomposition of SOM in buried soils to specific microbial taxa, and particularly to a decrease in abundance and activity of ECM fungi, and to the extent to which bacterial decomposers are able to act as their functional substitutes.     

Soil respiration of two dominant tundra communities under controlled temperatures in Changbai Mountain, Northeast China

Numerous seasonal snowpacks exist on alpine tundra of Changbai Mountain, Northeast China. The structure and species composition are distinct between snowpack and nonsnowpack communities, implying the difference in ecological processes in the subsurface. In order to clarify the relationship between soil respiration with thermal condition in snowpacks, as well as its seasonal variation, the respiration in response to temperature was measured based on simulated experiments. In addition to soil temperature, primary productivity was also investigated by harvesting the current-year aboveground growth. Field sampling was conducted in two community types: Rhododendron aureum community occurred in snowpack and Vaccinium uliginosum var. alpinum community (as reference) in snow-free area. An Li-8100 soil respiration system (Li-COR Co.) was used for measuring CO₂ release. Soil organic matter, total nitrogen and available nitrogen were analyzed. Hydrolizable nitrogen in Vaccinium community was 370–585 mg kg^?1, total nitrogen was 0.298%–0.468%, and organic matter was 13.5%–17.3%. In Rhododendron community, hydrolizable nitrogen was 445–583 mg kg^?1, total nitrogen was 0.465%–0.696%, and organic matter was 15%–22%. Organic matter within 10 cm depth was 4.07 kg m^?2 in Vaccinium community, and 5.31 kg m^?2 in the other. Temperature-dependent equations indicated that Q₁₀ values in both communities were around 2, with the ranges of 1.81–2.67 in Vaccinium community and 1.67–2.21 in Rhododendron community. The temperature-dependent equation was formed as y = ae^bx, where y is respiration rate (μmol kg^?1 h^?1), a and b are coefficients, and x is temperature in Celsius degree. Coefficient a was 52–148 in Vaccinium community and 34–167 in Rhododendron community, with significant variation among samples taken in different years. The daily respiration (g C kg^?1 d^?1) equation was y = 0.021733e^0.084063x for Vaccinium community, and y = 0.023482e^0.06x for Rhododendron community, both varied significantly with season. As to yearly respiration rate, it was 8.57–17.96 g C kg^?1 a^?1 in Vaccinium community, with a peak in May and relatively even in other time. The yearly respiration calculated by an integrated equation fitted with samples taken in all seasons was 10.24 g C kg^?1 a^?1. By covering Vaccinium community with a quilt in the field during the winter, soil temperature was slightly raised. During the frozen season, the temperature was raised by approximately 1.5 °C. Hence the annual respiration was 544.41 g C m^?2, 12 g C m^?2 higher than that of the reference. Respiration for Rhododendron community was in the range of 4.57–21.15 g C kg^?1 a^?1, with its maximum in May. By the integrated equation, it was 10.35 g C kg?1a^?1or 537 g C m^?2 a^?1. The yearly respiration was 441–544 g C m^?2 a^?1 in Vaccinium community and 449–486 g C m^?2 a^?1 in Rhododendron community. Taking the form of respiration on the basis of per kg of organic carbon, it was 118 g C (kg C)^{? 1} a^?1 in Vaccinium community and 101 g C (kg C)^{? 1} a^?1 in Rhododendron community. In particular, winter respiration in Vaccinium community was 2.10 g C kg?1, or 20.50% of yearly total, and merely 1.59% in the coldest month. While in Rhododendron community, it was 3.40 g C kg?1, or 32.84% of yearly total, significantly higher than that in Vaccinium community. The respiration in Rhododendron community at elevation 2260 m was 468.21 g C m^?2 a^?1, and the biomass growth was 400 g C m^?2 a^?1. In contrast, due to the thinner snow cover, in elevation 2036 m the biomass growth was 225.0 g C m^?2 a^?1 versus the respiration rate of 486.60 g C m^?2 a^?1. Leaf area index varied significantly in Rhododendron communities, ranging from 1.48 to 3.14, also owing to the difference in snow depth. As a contrary, in Vacciniumu community, the biomass growth was 120.75 g C m^?2 a^?1 and the leaf area index was 1.58. In conclusion, snowpacks provide a suitable condition for microbiomes in the winter, and contribute a large proportion of respiration. This also implies the vigorous activity in nitrogen release during the frozen season, which results in the rapid thriving of plants after snowmelt.