Early growth responses of mangroves to different rates of nitrogen and phosphorus supply

Experiments were conducted in an outdoor facility to quantify growth responses of six mangrove species to rates of dissolved inorganic nitrogen and phosphorus supply mimicking the range of N and P mineralization rates in natural soils. Growth of all six species on nitrogen was nonlinear. Stem extension rates of Rhizophora apiculata and Xylocarpus granatum were enhanced to the highest rate of N supply (50 mmol m^− 2 d^− 1); Bruguiera gymnorrhiza, Avicennia marina, and Xylocarpus moluccensis stem growth leveled off by 10 mmol m^− 2 d^− 1. Stem growth of Ceriops tagal peaked at 24-26 mmol N m^− 2 d^− 1. Except for A. marina and C. tagal, rates of biomass increase declined at the highest supply rate, indicating NH₄⁺ toxicity. At different rates of P supply, stem extension rates and rates of biomass increase of R. apiculata and C. tagal best-fit Gaussian curves and B. gymnorrhiza stem growth and biomass increase best-fit sigmoidal and Gaussian curves, respectively; X. moluccensis stem and biomass growth increased linearly, but stem and biomass growth rates of A. marina did not vary in relation to P supply. Stem growth of X. granatum was Gaussian but rates of biomass increase best-fit a quadratic equation. Changes in leaf and root N and P content mirrored the growth responses. As rates of N and P mineralization in natural mangrove soils overlap with the lowest rates of N and P supplied in these experiments, the growth responses imply that mangroves are intrinsically nutrient-limited at mineralization rates often encountered in nature. Such species specificity may have significant implications for recruitment success and the establishment of species gradients within mangrove forests.     

Effects of nutrient amendments on modular growth,flowering effort and reproduction of snowbed plants

Background: There have been few studies on the effects on alpine flora and vegetation of an increase in nutrient availability. Two main potential sources of increased nutrient availability in alpine ecosystems are enhanced mineralisation caused by climate warming and atmospheric nitrogen deposition. Little is known on how life history traits of different species are related at individual and community levels to enhanced nutrient availability.

Aims: We investigated the effects of nitrogen and phosphorus addition on the modular growth, flowering and germination of four species: two snowbed specialists and two alpine generalists.

Methods: We established in a late snowbed at the Gavia Pass, Italian Alps, a factorial experiment with four fertiliser treatments (N, P, Low N+P, and High N+P) and an unfertilised control. Nutrients were applied in 2003–2006 and we recorded the number of modules per individuals, total number of flowers, number of flowers per flowering module, and calculated the percentage of flowering modules in 2005 and 2006, and counted the number of seedlings in 2006.

Results: The modular growth and flowering effort of the species appeared to be co-limited by N and P. The alpine generalists showed greater responses to fertilization in vegetative growth and flowering compared with snowbed specialists. The number of seedlings recorded indicated species-specific responses to nutrient addition.

Conclusions: Our results suggest that enhanced nutrient availability stimulates modular growth and flowering effort in responsive alpine generalist species. This, in turn, could lead to an increase in their abundance, leading to changes in community structure in snowbeds with enhanced nutrient availability.     

Effects of experimental shifts in flowering phenology on plant-pollinator interactions

Climate change has led to phenological shifts in flowering plants and insect pollinators, causing concern that these shifts will disrupt plant-pollinator mutualisms. We experimentally investigated how shifts in flowering onset affect pollinator visitation for 14 native perennial plant species, six of which have exhibited shifts to earlier flowering over the last 70 years and eight of which have not. We manipulated flowering onset in greenhouses and then observed pollinator visitation in the field. Five of six species with historically advanced flowering received more visits when flowering was experimentally advanced, whereas seven of eight species with historically unchanged flowering received fewer visits when flowering earlier. This pattern suggests that species unconstrained by pollinators have advanced their flowering, whereas species constrained by pollinators have not. In contrast to current concern about phenological mismatches disrupting plant-pollinator mutualisms, mismatches at the onset of flowering are not occurring for most of our study species.     

Effects of experimental warming and nitrogen enrichment on leaf and litter chemistry of a wetland grass,Phragmites australis

As global climate is warming and the nitrogen cycle accelerates, plants are likely to respond not only by shifting community composition, but also by adjusting traits such as tissue chemistry. We subjected a widespread wetland plant, Phragmites australis, to increased nitrate supply and elevated temperature in enclosures that were established in a littoral permanently submerged freshwater marsh. The nitrogen (N) and phosphorus (P) concentrations in green leaves ranged from 11.4 to 13.8 mg N and from 1.5 to 2.0 mg P g⁻¹ dry mass. While the N concentration changed little in brown litter, the P concentration decreased to 0.53–0.65 mg P g⁻¹ litter dry mass. Neither experimental warming of the water and sediment surface, nor nitrate enrichment during the growing season affected nitrogen or phosphorus concentrations in green leaves. Concentrations of the two major structural carbon compounds in plant litter, cellulose and lignin, were also unaffected, ranging from 32.1 to 34.2% of dry mass for cellulose and from 16.3 to 17.7% of dry mass for lignin. Warming, however, significantly increased the nitrogen concentration of fully brown leaf litter. Thus, temperature appears to be more important than the supply of dissolved N in the water, especially in affecting leaf litter N concentrations in P. australis, even when only water but not air temperature is increased. This result may have implications for decomposition processes and decomposer food webs, which both depend on the quality of plant litter.     

Influence of a pulsed nitrogen supply on growth and nitrogen uptake in alpine graminoids

The supply of N in alpine soils is influenced by environmental factors (freeze-thaw, drying-rewetting, release of N from winter snowpack) which lead to a pulsed nature in plant N availability. To address the ability of alpine species to acquire N and grow when N is supplied in a pulsed manner, six alpine graminoid species, 3 sedges (Cyperaceae) and 3 grasses (Poaceae), were grown under 3 treatments: low and high N supply applied 3 times weekly, and a pulsed N supply applied once weekly at the same concentration as the high N treatment, but with the same total N supply as the low N treatment. Growth, biomass allocation, and N uptake were the same in all species for plants grown under a pulsed N treatment relative to a constant N supply with the same amount of total N. Root:shoot ratios and uptake of experimentally applied ¹⁵N indicated there were no adjustments in growth allocation or root uptake capacity in the plants to enhance the uptake of N when supplied in a pulsed relative to a more constant supply. The fertility of the site from which the graminoids were collected did not influence the plants' ability to respond to a high versus a low N supply, but instead growth form was more important. Grasses exhibited variation in growth, biomass allocation, and N uptake in response to changes in N supply, while sedges did not.     

Effect of nitrogen,phosphorus and potassium availability on emergence,nodulation and growth of Trifolium medium L. in alkaline soil

Little is known about the effects of nutrient availability on the growth of Trifolium medium in alkaline soil. In 2010, a pot experiment (10 N, P and K fertiliser treatments) with seeding of T. medium into alkaline soil was performed and emergence of seedlings, survival, aboveground and belowground organs were studied. The positive effects of increased nutrient availability on seedling emergence ranged from 5% in the control to 17% in the high P treatment. The lowest mortality was in treatments with P and K supply and the highest in treatments with N supply, due to the sensitivity of young plants to high N availability. The highest values of most measured aboveground plant traits were recorded in treatments with simultaneous application of N, P and K. There were highly positive effects of P supply alone or in combination with N and K on the development of belowground organs. Taproot length ranged from 11.5 in high N to 40.2 cm in P treatment. There was a negative effect of N application on nodulation, especially in N treatments, where growth of T. medium was limited by insufficient P supply. The number of nodules per plant ranged from 0.8 to 4.5 in the high N and P treatments. As demonstrated in this study, T. medium is a potentially suitable legume for alkaline soils. It requires a relatively high P and K supply as well as moderate mineral N supply to achieve its maximum growth potential.     

Nutrient content of the seagrass Thalassia testudinum reveals regional patterns of relative availability of nitrogen and phosphorus in the Florida Keys USA

Between 1992 and 2000, we sampled 504 randomly chosen locations in theFlorida Keys, Florida, USA, for the elemental content of green leaves of theseagrass Thalassia testudinum. Carbon content ranged from29.4–43.3% (dry weight), nitrogen content from 0.88–3.96%, andphosphorus content from 0.048–0.243%. N and P content of the samples werenot correlated, suggesting that the relative availability of N and P variedacross the sampling region. Spatial pattern in C:N indicated a decrease in Navailability from inshore waters to the reef tract 10 km offshore;in contrast, the pattern in C:P indicated an increase in P availability frominshore waters to the reef tract. The spatial pattern in N:P was used to definea P-limited region of seagrass beds in Florida Bay and near shore, and anN-limited region of seagrass beds offshore. The close juxtaposition ofN–and P-limited regions allows the possibility that N loading from thesuburban Florida Keys could influence the offshore, N-limited seagrass bedswithout impacting the more nearshore, P-limited seagrass beds.     

Effects of N and P supply on phytoplankton in Bizerte Lagoon (western Mediterranean)

Enriched bottle experiments were conducted in situ during winter (January and February) and summer (July and August) 2001 to examine the effects of nutrient enrichments (+ N, + P and + NP) on phytoplankton in Bizerte Lagoon, Tunisia. Chlorophyll a (Chl a), ranging from 3.05 μg L⁻¹ in winter to 4.52 μg L⁻¹ in summer, was dominated by the small size-faction (<5 μm) during both seasons. However, the contribution of the large size-fraction (5-200 μm) to Chl a increased from winter (26%) to summer (37%). Similarly, the carbon biomass of the 5-200 μm algae increased during the July/August period that was characterised by the high proliferation of several diatom taxa. In winter, N was the limiting element for phytoplankton growth. Its addition alone (+ N) or with P (+ NP) increased both the <5 μm and 5-200 μm Chl a concentrations. There was no change in the phytoplankton size structure, with the small cells dominating the final algal biomass in all treatments after 5 days. In summer, N and P limited the phytoplankton, but small and large algae exhibited diverse responses to different nutrient enrichments: addition of P increased the Chl a only in the 5-200 μm fraction, the + N treatment enhanced both size classes, and the NP fertilisation mostly stimulated the biomass of large cells. Consequently, the N and P addition in summer was followed by a significant change in the phytoplankton size structure, since both size-fractions contributed equally to the final Chl a biomass. Within the 5-200 μm algal community, various taxa had diverse responses to the nutrient supply during both seasons, leading to a change in the final community composition. The autotrophic flagellates appeared to grow well under N-deficient conditions. In contrast, diatom growth and biomass were mostly stimulated by the N enrichment while dinoflagellates exhibited the highest increase in their growth and biomass with P fertilisation. Our results suggest that the increasing anthropogenic supply of nutrients in the lagoon may influence algal dynamics as well as productivity in different ways depending on the nutrient composition.     

Spatiotemporal variability of stone pine (Pinus pinea L.) growth response to climate across the Iberian Peninsula

Climate warming and increasing aridity have impacted diverse ecosystems in the Mediterranean region since at least the 1970s. Pinus pinea L. has significant environmental and socio-economic importance for the Iberian Peninsula, so a detailed understanding of its response to climate change is necessary to predict its status under future climatic conditions. However, variability of climate and uncertainties in dendroclimatological approach complicate the understanding of forest growth dynamics. We use an ensemble approach to analyze growth-climate responses of P. pinea trees from five sites along a latitudinal gradient in Spain over time. The growth responses to April-June precipitation totals were stronger in the north than in the south. Since the 1950s, the sensitivity of growth to April-June precipitation increased in the north and decreased in the south. Meteorological drought usually started in May in the southern sites, but in June-July in the northern sites. The water deficit in the southern sites is thus greater and more limiting for tree growth, and this likely accounts for the lower growth sensitivity during these months. Our results indicate that P. pinea has a high degree of plasticity, suggesting the species will withstand changing climatic conditions. However, growth response to drought regimes varies among P. pinea populations, suggesting that different populations have different capacities for acclimation to warmer and drier climate, and this may influence future vegetation composition.     

Effects of perennial neighbors and nitrogen pulses on growth and nitrogen uptake by Bromus tectorum

An experiment was conducted to determine if growth and biomass responsesof the annual grass Bromus tectorum are affected by themagnitude and timing of nitrogen (N) pulses and if these responses areinfluenced by different perennial neighbor species. Nitrogen(NH₄:NO₃) was applied in three pulse treatments of varyinginterpulse length (3-d, 9-d, or 21-d between N additions). The total amount of Nadded was the same among treatments; hence, both the frequency and magnitude ofN pulses varied (i.e., the longer the interpulse period,the greater the amount of N added for a single pulse).Bromus showed little response to the different N-pulsetreatments. The only characteristic that varied among pulse treatments wasspecific leaf area (SLA), which was significantly greater whenBromus was grown under the 21-d N pulse than when grownunder the 3-d or 9-d N pulses. Bromus height, leaf andtiller numbers, leaf area and aboveground biomass were not affected by theN-pulse treatments nor were tissue-N contents and concentrations. However,Bromus production and tissue-N were significantly differentwhen Bromus was grown with different perennial neighborspecies. Tiller production, aboveground biomass, and seed numbers ofBromus were lowest when the perennial neighbor was thetussock grass Agropyron desertorum, intermediate when theneighbor was the evergreen shrub Artemisia tridentata, andgreatest when the neighbor was the deciduous shrub Chrysothamnusnauseosus. N contents of Bromus leaves were alsolowest when the neighbor was Agropyron. In contrast, root Nuptake capacities were greatest for Agropyron-Bromus rootmixes and lowest for Chrysothamnus-Bromus root mixes. Theseresults suggest that perennial neighbors affect growth, seed production, and Nuptake of Bromus to a greater extent than the timing andmagnitude of N pulses.     

Effects of water depth and substrate type on growth dynamics and biomass allocation of Oryza rufipogon

Oryzarufipogon is known as the ancestor of Asian cultivated rice (Oryzasativa) and the most important germplasm for rice improvement. In this study, we investigated its growth and biomass allocation in response to water depth and substrate type. The results demonstrated that individual plant had an average weight of 18.98 g, 9.36 g, and 10.59 g and produced 77.7 seeds, 35.5 seeds, and 41.6 seeds in deep-, fluctuated-, and shallow water, respectively. Root-to-shoot ratios were 0.37 in deep water, 0.61 in fluctuated water level, and 0.56 in shallow water, reflecting larger investment in roots under water-level fluctuation and shallow water conditions. However, biomass allocation for sexual reproduction was no significant different among the three water levels. In substrates experiment, total biomass and seed production were significantly different between sediment types, and the averages were 10.59 g, 3.56 g, and 0.76 g in biomass and 41.6 seeds, 13.8 seeds, and 0.5 seeds per plant in lake sediment, river sand and clay, respectively. The number of tillers was significantly fewer in sandy and clay substrates than in lake sediments. Individual plant in clay substrates was significantly shorter than those in sandy and in lake sediment substrates. Our study suggests that the plasticity in morphology and biomass allocation of O.rufipogon appears to be an adaptation to the variability in water level and substrate conditions.     

Effects of temperature and nitrogen supply on the growth of timothy (Phleutn pratense L.)

Timothy was grown in controlled environments with day/night temperatures of 18.5/10° C. and 29.5/21° C, with and without extra nitrogen. High temperatures hastened all stages of development after inflorescence initiation. Anthesis occurred after 48 days when N was added and after 52 days without N. Anthesis did not occur until after 68 days at the lower temperatures, with or without N. Largest yields of leaves, stems and stubble were produced at all growth stages at the lower temperatures with N. This treatment gave the highest crop growth rate, which increased almost linearly with time. The lower temperatures with N gave many more and longer stems and more inflorescences than any other treatment. With N and high temperatures, there was no increase in crop growth rate after inflorescence emergence. Temperature had little effect on growth when no N was provided. With no added N, crop growth rate was retarded and increased very little after inflorescence initiation. Herbage produced at high temperatures had the lower percentages of water-soluble carbohydrates and digestible dry matter, but had the higher percentages of most minerals. N increased the percentage content of most minerals. Weights of stubble and of water-soluble carbohydrates in the stubble, and the numbers of stem bases and tillers, were larger at the lower temperatures, and were usually larger with added N in both temperature regimes. Nitrogen decreased the percentage content of carbohydrates in the stubble. Large haplocorms were produced at the low temperatures, but none developed at the high temperatures, indicating less carbohydrate storage. The results partly explain the vigorous growth of timothy in the cool, temperate regions of Europe and North America, and the small dry matter production, lower nutritional value of the herbage, and lack of persistence in the warm southern regions where rainfall is adequate.     

Effects of nitrogen supply and high temperature on the growth and physiology of the chickpea

Chickpeas were grown with or without nitrate nitrogen feeding, or nodulated with Rhizobium leguminosarum. High [40°C day, 25°C night (HT)] and moderate [25°C day, 177°C night (LT)] temperature regimes were employed during growth. Growth rates, photosynthetic capacity and enzymes of carbon and nitrogen metabolism were monitored to assess the acclimatory capacity of the chickpea. Initial growth rates were stimulated by high temperatures, particularly in nitrate-fed and nodulated plants. Older HT plants had fewer laterals, smaller leaves, and fewer flowers were produced than in LT plants. There was some indication of an acclimation of photosynthesis to high temperatures and this was independent of nitrogen supply. Rubisco activity was increased by high growth temperatures. However, HT plants also had higher transpiration rates and lower water use efficiency than LT plants both in respective growth conditions and when compared in a common condition. High temperatures reduced shoot nitrate reductase activity but had little effect on root activity, which was the same if not greater than activity in LT roots. The amino acid, asparagine, was found at high concentrations in all treatments. Concentrations were maintained throughout growth in HT plants but declined with age in LT plants.     

气候变化对我国华北地区冬小麦发育和产量的影响

验证作物模型在我国华北冬小麦主产区是否适应的基础上,采用作物模型与气候模式相结合的研究方法,定量化地模拟预测了未来100年气候变化对华北冬小麦生产的影响.结果表明,从2000～2004年,华北地区冬小麦产量的模拟值与实测值的变化趋势基本一致,且生育期和产量变化不大.未来100年内华北地区冬小麦的生长期可能会有所缩短,平均缩短8.4 d;产量也会有不同程度的下降,平均减产10.1％.适当采取应对措施可以有效降低冬小麦的减产趋势.     

磷胁迫对不同种源枫香生长及氮、磷吸收利用率的影响

基于枫香(Liquidambar formosana)作为先锋树种的生态价值及南方红壤缺磷的现状,采用裂区设计,以不同磷水平模拟磷胁迫砂培处理枫香三叶期幼苗,研究7个种源枫香对磷水平的响应差异.结果表明：不同种源枫香间耐磷胁迫差异显著.随磷胁迫的加剧,各种源的生物量和氮、磷吸收量减少,而利用率增加.高磷处理条件下,南昌和宜兴种源枫香生物量和氮、磷吸收量较高,利用率较低,南丹种源枫香的氮、磷利用率较高,吸收量较低;低磷处理时,南昌和南丹种源枫香的磷吸收量、利用率和生物量均较高.说明高磷时,枫香高生物量种源呈高效吸收;而低磷时,则呈高效吸收和高效利用的特点.南昌种源是优良的耐磷胁迫种源,南丹种源次之;磷不是枫香的限制性养分因子.叶片Δ（N/P）、磷效率和生物量可作为确定枫香耐磷胁迫的指标.     

N、P营养盐对海洋卡盾藻（Chattonella marina）生长的影响

在实验室条件下,设置不同的N、P浓度,研究N、P双因子限制(N:5-500ug·L-1,P:0.74-74ug·L-1,N:P=15)及单因子限制(N:500ug·L-1,P:0.74-741ug·L-1和P:74ug·L-1,N:5-500ug·L-1)对海洋卡盾藻生长的影响.结果表明:在高N、P浓度(N:500ug·L-1,P:74ug·L-1)条件下海洋卡盾藻具有相对较高的比生长率(O.788/d),稳定期持续时间较长,最大细胞密度可达8850 cells/ml.N、P限制能明显抑制海洋卡盾藻的生长,而N限制对海洋卡盾藻生长影响更大,N限制组的比生长率和稳定期细胞密度均明显低于P限制组和N、P双因子限制组.结果说明海洋卡盾藻生长对N变化更为敏感,但随着海洋污染的加剧,海水中N含量持续上升,卡盾藻可迅速爆发性增长并引发赤潮,这也许是近年来我国沿海卡盾藻赤潮频繁发生的重要原因之一.     

Effects of phosphorus and nitrogen amendments on the growth of Egeria najas

The effect of nutrient addition on the growth of E. najas was evaluated in a dose response experiment using sand amended with phosphorus (P) and nitrogen (N), and in enrichment trials with N and P amendments to natural sediments. Plants, water and sediment came from lagoons of the Upper Paraná River Floodplain and from Itaipu Reservoir (Brazil). Relative growth rates (RGRs) of E. najas shoots, based on dry mass (DM), varied from 0.03 to 0.060 d⁻¹ for both nutrients. Root:shoot biomass ratios were related to sediment exchangeable P (r = −0.419; P = 0.03) and N (r = −0.54; P = 0.006), however root RGR was not related to sediment nutrient concentrations. When natural sediments were amended with N and P, neither shoot nor root RGRs differed among treatments for substrata from either the reservoir or the floodplain lagoons (P > 0.05). Comparison of nutrient concentrations measured in natural sediments collected from several sites in both the Upper Paraná River Floodplain (range 49–213 μg P g⁻¹ DM; 36–373 μg N g⁻¹ DM) and Itaipu Reservoir (range 43–402 μg P g⁻¹ DM; 7.9–238 μg N g⁻¹ DM) showed that sediment N and P from these systems usually exceeded minimum requirements necessary for E. najas growth, as measured in the dose response experiment. Together, these results indicate that E. najas, at least in early stages of development, responds to sediment nutrient amendments and relies upon bottom sediments to meet its N and P requirements and that for at least two Brazilian ecosystems, growth of this species is not limited by insufficient sediment N or P. Thus, reducing N and P in water is not enough to control E. najas growth in short time periods in these ecosystems.     

Effects of localized nitrogen supply treatments on growth and root parameters in Pinus massoniana families under phosphorus deficiency

Aims A heterogeneous spatially distribution of nutrients in natural soil may affect plant growth. The objective of this study was to determine the effects of localized nitrogen (N) supply treatments on growth traits and root parameters among different families in Pinus massoniana.Methods Five families of P. massoniana seedlings from full-sib progenies were used as test materials (1, 25, 49, 52, and 57). This study included two conditions, (i.e. homogeneous phosphorus (P) deficiency vs. heterogeneous P efficiency) among soil layers in combination with four N supply treatments in a one-year pot experiment. These N supply treatments were: (1) Homogeneously high N along the soil profile (HHH); (2) high N-high N-low N (HHL); (3) low N-low N-high N (LLH); (4) low N-low N-on side with N addition and the other side without N supply (LLH/L).Important findings This study indicated that localized N supply treatment did enhance the growth of P. massoniana, and this enhancement mainly happened in the pattern of N applied to deep soil. The results showed: 1) Compared to the homogeneous low P condition, there were increase in the growth traits and root parameters of P. massoniana under heterogeneous low P condition. Particularly, the root length and root surface area under the heterogeneous P deficiency condition were 1.95 times and 2.11 times higher than that subjected to the homogeneous P deficiency. 2) Localized N supply treatment affected seedling growth, and there was a significant interaction among N supply pattern and P condition. In compared with homogeneous N supply treatment, the height, basal diameter and dry weight of seedlings increased significantly by localized N supply treatments (LLH and/or LLH/L) under both two P deficiency conditions. But when the seedlings parameters were enhanced under homogeneous P deficiency, they were inhibited under heterogeneous P deficiency subjected to HHL. 3) Within the two P conditions, LLH and LLH/L stimulated root proliferation significantly, and root parameters were significantly enhanced under the heterogeneous P deficiency condition. Specifically, the root length and root surface area subjected to LLH/L rather than HHH were significantly enhanced by 29.2% and 32.3%, respectively. However, the length and surface area of the roots were suppressed by HHL treatment. 4). There were significant differences in response to different N supply treatments among P. massoniana families Seedlings in the families of 49, 52, and 57 responded to the localized N supply treatments with increased root proliferation, which enhanced seedling dry mass. On the other hand, the seedling growth in the family of 25 were stimulated by N and (or) P concentration, while the response of seedlings in the family of 1 to local nitrogen supply was relatively slow and exhibited growth retardation.     

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.