Seasonal Dependent Effects of Flooding on Plant Species Survival and Zonation: a Comparative Study of 10 Terrestrial Grassland Species

Past research has provided compelling evidence that variation in flooding duration is the predominant factor underlying plant species distribution along elevation gradients in river floodplains. The role of seasonal variation in flooding, however, is far from clear. We addressed this seasonal effect for 10 grassland species by testing the hypothesis that all species can survive longer when flooded in winter than when flooded in summer. We carried out an inundation experiment under simulated conditions of summer and winter flooding in the greenhouse. The results showed that all species survived longer under winter floods than under summer floods. However, responses upon flooding were species-specific. All summer flood-tolerant species had high tolerance for winter floods as well, but summer flood sensitive species survived either a little longer, or dramatically longer when flooded under simulated winter conditions. Next, we examined whether winter or summer survival best predicted the lower distribution limits of the species as measured in a natural flooding gradient after an extremely long winter flood. We found a strong significant relationship between the lower distribution limits of species in the field and their tolerance to summer floods, although we measured the lower limits 14 years after the latest major summer flood. In contrast, no such significant relationship existed with species tolerance to winter floods. Some relatively intolerant species occurred at much higher floodplain elevations as was expected from their tolerance to winter inundation in the experiments. This suggests that zonation patterns as created by occasional summer floods may be maintained for a long time, probably due to the limited ability of species to re-colonise lower positions in the floodplain.     

Effects of human trampling and multispecies competition on early-phase development of a tread community

Effects of human trampling and multispecies competition on the development of a tread community in the first year were examined by comparing changes in the relative abundance of three main component species of tread communities,Plantago asiatica, Eragrostis ferruginea andEleusine indica, between monoculture and mixed culture along a trampling gradient. At low trampling levels in mixed culture,Ambrosia artemisiifolia var.elatior andDigitaria adscendens, which are common pioneer species of secondary succession, predominated and suppressed the tread community species. Severe trampling reduced markedly the predominance of the pioneer species, but not that of the tread community species. The maximum cover of the three tread commiunty species was lower in mixed culture than in monoculture. The trampling levels supporting the maximum cover were higher in mixed culture than in monoculture. The differences in these levels between monoculture and mixed culture varied among the three:P. asiatica< Eragrostis ferruginea<Eleusine indica. These results suggest that (1) the pioneer species interfere with the establishment of tread community species under lower trampling intensity, (2) heavier trampling reduces the competitive ability of pioneer species, while it favors the establishment of tread community species, (3), there are competitive interactions among the tread community species under higher trampling intensity, and (4) the species more susceptible to multispecies competition and tolerant to trampling are established in more heavily trampled habitats.     

Competition Is a Strong Driving Factor in Wetlands,Peaking during Drying Out Periods

The aim of the study is to investigate the relative importance of plant-plant interactions with regard to flooding and drought effect on perennial plant performances in wetlands. Flooding is expected to be the major driver and, accordingly, the importance of drought is hardly if ever taken into account. Focusing on five widespread species, the growth, the survival and the competitive ability of plants were monitored on permanent plots spread along two elevation gradients. Flooding duration and drought intensity were found to vary substantially along the ~ 0.5 meter range elevation gradient. Flooding and drought alternate over the hydrological year and the pin-point surveys were thus conducted over the course of one year. The data were modeled taking into account survival, recruitment and competitive growth throughout flooding and drying out periods. Flooding and drought both directly impacted the plant performances and their competitive effect, with the effect of drought being much more general among species and of higher magnitude than flooding. The importance of competition was found to be high for all species, particularly during the drying out period. It varied more along the flooding gradient than along the drought gradient. The higher flooding tolerance shown by the studied species compared to drought may be related to species specific growth timing together with efficient response traits. These results offer new insights into the filters operating over the species pools. This suggests that the drying out period and drought conditions may be even more important for species’ relative success and the importance of competition than the flooding pattern. The general applicability of this result, obtained in mild Atlantic climate and fertile wetlands, remains to be studied.     

Intensity and Importance of Competition for a Grass (Festuca rubra) and a Legume (Trifolium pratense) Vary with Environmental Changes

How plant competition varies across environmental gradients has been a long debate among ecologists. We conducted a growth chamber experiment to determine the intensity and importance of competition for plants grown in changed environmental conditions. Festuca rubra and Trifolium pratense were grown in monoculturs and in two- and/or three-species mixtures under three environmental treatments. The measured competitive variations in terms of growth (height and biomass) were species-dependent. Competition intensity for Festuca increased with decreased productivity, whilst competition importance displayed a humpback response. However, significant response was detected in neither competition intensity nor importance for Trifolium. Intensity and importance of competition followed different response patterns, suggesting that they may not be correlated along an environmental gradient. The biological and physiological variables of plants play an important role to determine the interspecific competition associated with competition intensity and importance. However, the competitive feature can be modified by multiple environmental changes which may increase or hinder how competitive a plant is.     

Distribution and abundance of trees in floodplain forests of the Wisconsin River: Environmental influences at different scales

Questions: 1. How do physiography, flooding regime, landscape pattern, land‐cover history, and local soil conditions influence the presence, community structure and abundance of overstorey trees? 2. Can broad‐scale factors explain variation in the floodplain forest community, or are locally measured soil conditions necessary? Location: Floodplain of the lower 370 km of the Wisconsin River, Wisconsin, USA. Methods: Floodplain forest was sampled in 10 m × 20 m plots [n= 405) during summers of 1999 and 2000 in six 12‐ to 15‐km reaches. Results: Species observed most frequently were Fraxinus pennsylvanica, Acer saccharinum and Ulmus americana. Physiography (e.g. geographic province) and indicators of flooding regime (e.g. relative elevation and distance from main channel) were consistently important in predicting occurrence, community composition, and abundance of trees. Correspondence analysis revealed that flood‐tolerant and intolerant species segregated along the primary axis, and late‐successional species segregated from flood‐tolerant species along the secondary axis. Current landscape configuration only influenced species presence or abundance in forests that developed during recent decades. Land‐cover history was important for tree species presence and for the abundance of late‐successional species. Comparison of statistical models developed with and without soils data suggested that broad‐scale factors such as geographic province generally performed well. Conclusions: Physiography and indicators of flood regime are particularly useful for explaining floodplain forest structure and composition in floodplains with a relatively high proportion of natural cover types.     

Fast and furious: Early differences in growth rate drive short‐term plant dominance and exclusion under eutrophication

1. The reduction of plant diversity following eutrophication threatens many ecosystems worldwide. Yet, the mechanisms by which species are lost following nutrient enrichment are still not completely understood, nor are the details of when such mechanisms act during the growing season, which hampers understanding and the development of mitigation strategies.
2. Using a common garden competition experiment, we found that early‐season differences in growth rates among five perennial grass species measured in monoculture predicted short‐term competitive dominance in pairwise combinations and that the proportion of variance explained was particularly greater under a fertilization treatment.
3. We also examined the role of early‐season growth rate in determining the outcome of competition along an experimental nutrient gradient in an alpine meadow. Early differences in growth rate between species predicted short‐term competitive dominance under both ambient and fertilized conditions and competitive exclusion under fertilized conditions.
4. The results of these two studies suggest that plant species growing faster during the early stage of the growing season gain a competitive advantage over species that initially grow more slowly, and that this advantage is magnified under fertilization. This finding is consistent with the theory of asymmetric competition for light in which fast‐growing species can intercept incident light and hence outcompete and exclude slower‐growing (and hence shorter) species. We predict that the current chronic nutrient inputs into many terrestrial ecosystems worldwide will reduce plant diversity and maintain a low biodiversity state by continuously favoring fast‐growing species. Biodiversity management strategies should focus on controlling nutrient inputs and reducing the growth of fast‐growing species early in the season.

     

Are variations of direct and indirect plant interactions along a climatic gradient dependent on species’ strategies? An experiment on tree seedlings

Investigating how interactions among plants depend on environmental conditions is key to understand and predict plant communities’ response to climate change. However, while many studies have shown how direct interactions change along climatic gradients, indirect interactions have received far less attention. In this study, we aim at contributing to a more complete understanding of how biotic interactions are modulated by climatic conditions. We investigated both direct and indirect effects of adult tree canopy and ground vegetation on seedling growth and survival in five tree species in the French Alps. To explore the effect of environmental conditions, the experiment was carried out at 10 sites along a climatic gradient closely related to temperature. While seedling growth was little affected by direct and indirect interactions, seedling survival showed significant patterns across multiple species. Ground vegetation had a strong direct competitive effect on seedling survival under warmer conditions. This effect decreased or shifted to facilitation at lower temperatures. While the confidence intervals were wider for the effect of adult canopy, it displayed the same pattern. The monitoring of micro‐environmental conditions revealed that competition by ground vegetation in warmer sites could be related to reduced water availability; and weak facilitation by adult canopy in colder sites to protection against frost. For a cold‐intolerant and shade‐tolerant species (Fagus sylvatica), adult canopy indirectly facilitated seedling survival by suppressing ground vegetation at high temperature sites. The other more cold tolerant species did not show this indirect effect (Pinus uncinata, Larix decidua and Abies alba). Our results support the widely observed pattern of stronger direct competition in more productive climates. However, for shade tolerant species, the effect of direct competition may be buffered by tree canopies reducing the competition of ground vegetation, resulting in an opposite trend for indirect interactions across the climatic gradient.     

Using three pairs of competitive indices to test for changes in plant competition under different resource and disturbance levels

Questions: How do different resource and disturbance levels interact to affect competition? How do different indices of competition change the interpretation of how competition changes under different resource and disturbance conditions? Location: Greenhouse, Thompson Rivers University, Kamloops, British Columbia, Canada. Methods: Three pairs of indices that have been used to differentiate the predictions of Grime (CSR) and Tilman's (R^*) theories were used to assess competition on two species of temperate bunchgrass, (Pseudorogeneria spicata and Festuca campestris) grown in a greenhouse on stress and disturbance gradients. Stress was created by manipulating the amount of water (high, low) and concentration of nutrient solution (high, low) added to pots, while disturbance was created by clipping (clipped, unclipped) in a fully factorial design. Plants were grown individually or with a single neighbour. The three pairs of indices were: (1) absolute and relative competition; (2) competitive effect and response; and, (3) competitive importance and intensity. Results: Absolute competition and competitive importance were the only indices responsive to the resource gradient, which supports CSR theory, and also the only ones to record an effect of disturbance on the strength of competition – under high resource conditions. The other indices showed few responses along the gradients, which supports R^* theory. Measures of competitive effect and response did not differentiate the two theories. Conclusion: We show that some indices of competition show a decline with increased stress and disturbance, while other indices do not. Therefore, it is necessary to choose a competition index appropriate to the question being asked. Competitive importance and absolute competition were responsive to changes in stress and disturbance, while the other indices were not.     

Effects of stream flooding on the distribution and diversity of groundwater‐dependent vegetation in riparian areas

1. Effects of the frequency and duration of flooding on the structural and functional characteristics of riparian vegetation were studied at four sites (n = 80, 50 × 50 cm, plots) along medium‐sized naturally meandering lowland streams. Special focus was on rich fens, which – due to their high species richness – are of high priority in nature conservation. 2. Reed beds, rich fens and meadows were all regularly flooded during the 20‐year study period, with a higher frequency in reed bed areas than in rich fen and meadow areas. In rich fens, species richness was higher in low frequency flooded areas (≤3 year^?1) than in areas with a high frequency of flooding (>3 year^?1) or no flooding, whereas species richness in reed beds and meadows was unaffected by flood frequency. 3. The percentage of stress‐tolerant species was higher in low intensity flooded rich fen areas than in high intensity and non‐flooded areas, indicating that the higher species richness in low frequency flooded rich fens was caused by competitive release. We found no indication that increased productivity was associated with high flooding frequencies. 4. We conclude that the restoration of morphological features in stream channels to increase the flooding regime can be beneficial for protected vegetation within riparian areas, but also that groundwater discharge thresholds and critical levels for protected vegetation should be identified and considered when introducing stream ecosystem restoration plans.     

Relationships between vegetation patterns and hydroperiod on the Roanoke River floodplain,North Carolina

This study quantified relationships between forest composition and flooding gradients on the Roanoke River floodplain, North Carolina. Because flooding is highly variable in time and space, the research was designed to determine the specific hydrological parameters that control woody species abundance on the landscape scale. I specifically tested the importance of spring vs. yearly flood duration, as well as flood duration during hydrologically wet vs. dry years. Field vegetation samples of woody species composition were integrated with spatial data from a Landsat Thematic Mapper (TM) classification and a flood simulation model derived in part from synthetic aperture radar (SAR) imagery. Flood simulations were output and summarized for the periods 1912–1950 (before dams were constructed on the river) and 1965–1996 (after all of the dams were completed). Tenth percentile (dry), median, and 90th percentile (wet) hydroperiod (flood duration) regimes were generated for the spring and year, both pre- and post-dam. Detrended correspondence analysis (DCA) was used to ordinate the plot data, and correlation/regression between ordination axis scores and the flood variables were used to explore the relationships between flooding and species composition. Nineteenth percentile hydroperiod (i.e., wet conditions) correlated most strongly with DCA axis 1 (r>0.9), indicating that inundation during extremely wet years strongly controls species composition on the floodplain. The results were used to quantitatively determine the niche width for both species and mapped vegetation classes in terms of number of days flooded annually and during the spring growth period. The results suggest that spring hydroperiod is an important mechanism that may drive competitive sorting along the flooding gradient, especially during the early years of succession (i.e., pre-dam, which represents the period during which most of the forests sampled were established), and that annual hydroperiod affects the relative dominance of species as the forests mature.     

Response of Plant Height,Species Richness and Aboveground Biomass to Flooding Gradient along Vegetation Zones in Floodplain Wetlands,Northeast China

Flooding regime changes resulting from natural and human activity have been projected to affect wetland plant community structures and functions. It is therefore important to conduct investigations across a range of flooding gradients to assess the impact of flooding depth on wetland vegetation. We conducted this study to identify the pattern of plant height, species richness and aboveground biomass variation along the flooding gradient in floodplain wetlands located in Northeast China. We found that the response of dominant species height to the flooding gradient depends on specific species, i.e., a quadratic response for Carex lasiocarpa, a negative correlation for Calamagrostis angustifolia, and no response for Carex appendiculata. Species richness showed an intermediate effect along the vegetation zone from marsh to wet meadow while aboveground biomass increased. When the communities were analysed separately, only the water table depth had significant impact on species richness for two Carex communities and no variable for C. angustifolia community, while height of dominant species influenced aboveground biomass. When the three above-mentioned communities were grouped together, variations in species richness were mainly determined by community type, water table depth and community mean height, while variations in aboveground biomass were driven by community type and the height of dominant species. These findings indicate that if habitat drying of these herbaceous wetlands in this region continues, then two Carex marshes would be replaced gradually by C. angustifolia wet meadow in the near future. This will lead to a reduction in biodiversity and an increase in productivity and carbon budget. Meanwhile, functional traits must be considered, and should be a focus of attention in future studies on the species diversity and ecosystem function in this region.     

Can germination explain the distribution of tree species in a savanna wetland?

The relationship between seed germination and ecological niche is determined by matching germination characteristics with environmental features. In this study, we selected tree species occurring in the largest savanna wetland in South America – the Pantanal. Very few species are endemic or exclusively found in savanna wetlands, and the majority of tree species occurring in the Pantanal are also found in the neighbouring Brazilian Cerrado, a drier vegetation type that does not flood. We investigated the relationship between germination characteristics and occurrence of savanna trees in wetlands testing the hypothesis that such seeds are tolerant to flooding. We also addressed the question of whether seed tolerance to flood, assessed by survival analysis, explains tree distribution along a gradient of flooding intensity. In this flooding gradient, widely distributed species are those that occur in areas subjected to low as well as to high flooding intensity whereas restricted distributed species are those that occur only in areas subjected to a low level of flood. Seeds from tree species occurring in areas subjected to different flooding intensities were collected. Seed tolerance and germination during and after both one and two months of simulated flood were evaluated. Our results show that seeds of most of the studied savanna species tolerated submergence, which helps to explain their occurrence and wide distribution in wetlands. Nevertheless, germination behaviour checked by survival functions (i.e. how germination is distributed over time) partially explained tree species distribution along a flooding gradient. We conclude that seed tolerance to flooding is one of the components of the regeneration niche that determines tree occurrence and distribution at the regional scale, from savanna to wetland, but not at a local scale along a flooding gradient.     

Disentangling the relative importance of climate,size and competition on tree growth in Iberian forests: implications for forest management under global change

Most large‐scale multispecies studies of tree growth have been conducted in tropical and cool temperate forests, whereas Mediterranean water‐limited ecosystems have received much less attention. This limits our understanding of how growth of coexisting tree species varies along environmental gradients in these forests, and the implications for species interactions and community assembly under current and future climatic conditions. Here, we quantify the absolute effect and relative importance of climate, tree size and competition as determinants of tree growth patterns in Iberian forests, and explore interspecific differences in the two components of competitive ability (competitive response and effect) along climatic and size gradients. Spatially explicit neighborhood models were developed to predict tree growth for the 15 most abundant Iberian tree species using permanent‐plot data from the Spanish Second and Third National Forest Inventory (IFN). Our neighborhood analyses showed a climatic and size effect on tree growth, but also revealed that competition from neighbors has a comparatively much larger impact on growth in Iberian forests. Moreover, the sensitivity to competition (i.e. competitive response) of target trees varied markedly along climatic gradients causing significant rank reversals in species performance, particularly under xeric conditions. We also found compelling evidence for strong species‐specific competitive effects in these forests. Altogether, these results constitute critical new information which not only furthers our understanding of important theoretical questions about the assembly of Mediterranean forests, but will also be of help in developing new guidelines for adapting forests in this climatic boundary to global change. If we consider the climatic gradients of this study as a surrogate for future climatic conditions, then we should expect absolute growth rates to decrease and sensitivity to competition to increase in most forests of the Iberian Peninsula (in all but the northern Atlantic forests), making these management considerations even more important in the future.     

高寒草甸植物群落物种多样性和生产力关系的光竞争研究

通过施肥形成的生产力由低到高的过程中,物种多样性往往降低。总体竞争假说认为对所有资源的竞争作用对多样性的影响随着生产力提高而加剧,导致物种多样性的下降;光竞争假说则认为随着生产力提高,种间竞争从低生产力时的地下竞争转向高生产力时的光竞争,是光竞争导致了物种多样性的下降。为了验证这两种假说,本文通过在甘南玛曲高寒草甸的均匀施肥实验,研究了光竞争对高寒草甸植物群落物种多样性和生产力关系的影响。结果表明：(1)随着施肥梯度的增加,大部分植物的生长速率加快,高度和叶面积增加;(2)随着施肥梯度的增加,植物群落地上总的生物量提高,叶面积指数增加,透光率降低,物种多样性减少;(3)个体大小不对称的光竞争导致了高寒草甸植物群落物种多样性随施肥梯度的增加而减少。     

Sapling dynamics in a southeastern Texas floodplain forest

Abstract. How much temporal variation in recruitment, mortality and change in size class occurs in the sapling layer of mature temperate forests in the absence of large‐scale exogenous disturbance? Using 15 years of data from a flood‐plain forest in Big Thicket National Preserve, we found that year‐to‐year variation in demographic parameters was greater than we originally expected. Death rates were generally more variable than recruitment rates, and were much more variable for large saplings than for small ones. Small saplings of the 10 most common species had at least one year when they experienced two to eight times their long‐term mean recruitment and death rates. Large saplings had at least one year when they experienced three to 10 times their long‐term mean death rates and at least one year with two to seven times the long‐term mean recruitment rate. Temporal patterns in sapling death rates were related to flooding patterns, while temporal patterns in recruitment were related to the Palmer Drought Severity Index, an indicator of drought severity and soil moisture availability. We also identified apparently synchronous patterns of demographic response among less flood‐tolerant species which differed from the responses of more flood‐tolerant species. We demonstrated the effects of both climatic variation and light variation in affecting stand‐wide sapling demographics in a forest where canopy gaps are important for regeneration, and where chronic understorey disturbance favours growth over survivorship as a sapling strategy.     

Interspecific competition alters leaf stoichiometry in 20 grassland species

The extensive use of traits in ecological studies over the last few decades to predict community functions has revealed that plant traits are plastic and respond to various environmental factors. These plant traits are assumed to predict how plants compete and capture resources. Variation in stoichiometric ratios both within and across species reflects resource capture dynamics under competition. However, the impact of local plant diversity on species‐specific stoichiometry remains poorly studied. Here, we analyze how spatial and temporal diversity in resource‐acquisition traits affects leaf elemental stoichiometry of plants (i.e. the result of resource capture) and how flexible this stoichiometry is depending on the functional composition of the surrounding community. Therefore, we assessed inter‐ and intraspecific variations of leaf carbon (C), nitrogen (N), and phosphorus (P) (and their ratios) of 20 grassland species in a large trait‐based plant diversity experiment located in Jena (Germany) by measuring leaf elemental concentrations at the species‐level along a gradient in plant trait dissimilarity. Our results show that plants showed large intra‐ and interspecific variation in leaf stoichiometry, which was only partly explained by the functional group identity (grass or herb) of the species. Elemental concentrations (N, P, but not C) decreased with plant species richness, and species tended to become more deviant from their monoculture stoichiometry with increasing trait dissimilarity in the community. These responses differed among species, some consistently increased or decreased in P and N concentrations; for other species, the negative or positive change in P and N concentrations increased with increasing trait difference between the target species and the remaining community. The strength of this relationship was significantly associated to the relative position of the species along trait gradients related to resource acquisition. Trait‐difference and trait‐diversity thus were important predictors of how species’ resource capture changed in competitive neighbourhoods.     

Competition and evolution along environmental gradients: patterns, boundaries and sympatric divergence

The present study examined how competitive interactions and environmental conditions generate species boundaries and determine species distributions. A spatially explicit, quantitative genetic, two-species competition model was used to manipulate the strengths of competition, gene flow and local adaptation along environmental gradients. This allowed us to assess the long-term persistence of each species and whether the ranges they inhabited had boundaries in space or were unlimited. We found that a species boundary arises along less steep environmental gradients when the strength of stabilizing selection and diversifying selection are similar. We also found that a species boundary may arise along shallow environmental gradients if interspecific competition is more intense than intraspecific, which relaxes previous requirements for steep gradients for generating range limits. We determined an analytical form for the critical environmental gradient as a function of ecological and genetic parameters at which a species boundary is expected to arise by competition. Results suggest an alternative to resource competition as an explanation for phenotypic divergence between sympatric competitors. Competitors sharing a trait that is under stabilizing selection along an environmental gradient may segregate spatially and evolve in different regions, with phenotypic sympatric divergence reflecting the resulting clines. Along various types of environmental gradients, variation in stabilizing selection intensities could lead to contrasting patterns in the distribution of species. For stabilizing selection strengths in accord with field data estimates, this study predicts that the level of sympatric character divergence would be limited along environmental gradients.     

The contribution of persistent soil seed banks and flooding to the restoration of alluvial meadows

Restoration of species-rich flood meadows impoverished by agricultural intensification is an important challenge. The relationships between flooding regime and soil seed bank were compared in three successive meadow communities (hygrophilic, mesohygrophilic and mesophilic) distinguished along a topographic and hydric gradient. Differences in flood duration and frequency between the three associations allowed the study of the contribution of floods to soil seed bank richness and density. No significant difference was found in species richness among the three soil seed banks, whereas the densities were significantly higher in the wettest community. The three seed bank compositions were clearly distinguished along the hydric gradient. In fact, the three seed bank types constituted a species poor version of the meadow communities to which they belong. Flood contributions appear to play a minor role in seed bank enrichment. Thus, seed dispersal by flood water would probably be insufficient to enable the restoration of alluvial meadows.     

Gradient analysis of spider communities in a streamside forest

Summary Species composition and diversity of a guild of wandering spiders was studied by pitfall trapping over an elevational gradient in an Illinois streamside forest. Differences in flooding frequency and their effect on the litter habitat (removal and/or compression) account for a majority of the variation in the number of species between elevations. Changes in spider communities with elevation over the flooding gradient are indicative of a transition from a harsh to a moderate environment: (1) increased abundance and species diversity; (2) decreased dominance of flood tolerant species accompanied by increased dominance of species with specialized microhabitats found in complex litter; (3) greater similarity in species composition between sites; and, (4) a change in species-abundance curves from a geometric series to a lognormal distribution. The influence of the flooding regime in regulating community structure of spiders is discussed. A multiple regression equation including flood frequency and litter depth as variables was used to predict the impact of altered flooding regimes (due to reservoir construction downstream) on spider diversity.     

Intrinsic and extrinsic factors acting on the reproductive process in alpine‐snowbed plants: roles of phenology,biological interaction,and breeding system

Pollinator activity and competition for pollinators lead to quantitative and qualitative pollen limitations on seed production and affect the reproductive success of plant species, depending on their breeding system (e.g., self‐compatibility and heterospecific compatibility) and genetic load (e.g., inbreeding depression and hybrid inviability). In alpine ecosystems, snowmelt regimes determine the distribution and phenology of plant communities. Plant species growing widely along a snowmelt gradient often grow with different species among local populations. Their pollinators also vary in their abundance, activity, and behavior during the season. These variations may modify plant–pollinator and plant–plant interactions. We integrated a series of our studies on the alpine dwarf shrub, Phyllodoce aleutica (Ericaceae), to elucidate the full set of intrinsic (species‐specific breeding system) and extrinsic factors (snow condition, pollinator activity, and interspecific competition) acting on their reproductive process. Seasonality of pollinator activity led to quantitative pollen limitation in the early‐blooming populations, whereas in the late‐blooming populations, high pollinator activity ensured pollination service, but interspecific competition for pollinators led to qualitative and quantitative pollen limitation in less competitive species. However, negative effects of illegitimate pollen receipt on seed‐set success might be reduced when cryptic incompatibility systems (i.e., outcross pollen grains took priority over self‐ and heterospecific pollen grains) could effectively prevent ovule and seed discounting. Our studies highlight the importance of species‐specific responses of plant reproduction to changing pollinator availability along environmental gradients to understand the general features of pollination networks in alpine ecosystems.