Contrasting effects of warming and increased snowfall on Arctic tundra plant phenology over the past two decades

Recent changes in climate have led to significant shifts in phenology, with many studies demonstrating advanced phenology in response to warming temperatures. The rate of temperature change is especially high in the Arctic, but this is also where we have relatively little data on phenological changes and the processes driving these changes. In order to understand how Arctic plant species are likely to respond to future changes in climate, we monitored flowering phenology in response to both experimental and ambient warming for four widespread species in two habitat types over 21 years. We additionally used long‐term environmental records to disentangle the effects of temperature increase and changes in snowmelt date on phenological patterns. While flowering occurred earlier in response to experimental warming, plants in unmanipulated plots showed no change or a delay in flowering over the 21‐year period, despite more than 1 °C of ambient warming during that time. This counterintuitive result was likely due to significantly delayed snowmelt over the study period (0.05–0.2 days/yr) due to increased winter snowfall. The timing of snowmelt was a strong driver of flowering phenology for all species – especially for early‐flowering species – while spring temperature was significantly related to flowering time only for later‐flowering species. Despite significantly delayed flowering phenology, the timing of seed maturation showed no significant change over time, suggesting that warmer temperatures may promote more rapid seed development. The results of this study highlight the importance of understanding the specific environmental cues that drive species’ phenological responses as well as the complex interactions between temperature and precipitation when forecasting phenology over the coming decades. As demonstrated here, the effects of altered snowmelt patterns can counter the effects of warmer temperatures, even to the point of generating phenological responses opposite to those predicted by warming alone.     

Phenological response of tundra plants to background climate variation tested using the International Tundra Experiment

The rapidly warming temperatures in high-latitude and alpine regions have the potential to alter the phenology of Arctic and alpine plants, affecting processes ranging from food webs to ecosystem trace gas fluxes. The International Tundra Experiment (ITEX) was initiated in 1990 to evaluate the effects of expected rapid changes in temperature on tundra plant phenology, growth and community changes using experimental warming. Here, we used the ITEX control data to test the phenological responses to background temperature variation across sites spanning latitudinal and moisture gradients. The dataset overall did not show an advance in phenology; instead, temperature variability during the years sampled and an absence of warming at some sites resulted in mixed responses. Phenological transitions of high Arctic plants clearly occurred at lower heat sum thresholds than those of low Arctic and alpine plants. However, sensitivity to temperature change was similar among plants from the different climate zones. Plants of different communities and growth forms differed for some phenological responses. Heat sums associated with flowering and greening appear to have increased over time. These results point to a complex suite of changes in plant communities and ecosystem function in high latitudes and elevations as the climate warms.     

Impact of climate change on plant phenology in Mediterranean ecosystems

Plant phenology is strongly controlled by climate and has consequently become one of the most reliable bioindicators of ongoing climate change. We used a dataset of more than 200 000 records for six phenological events of 29 perennial plant species monitored from 1943 to 2003 for a comprehensive assessment of plant phenological responses to climate change in the Mediterranean region. Temperature, precipitation and North Atlantic Oscillation (NAO) were studied together during a complete annual cycle before phenological events to determine their relative importance and potential seasonal carry‐over effects. Warm and dry springs under a positive phase of NAO advance flowering, leaf unfolding and fruiting dates and lengthen the growing season. Spatial variability of dates (range among sites) was also reduced during warm and dry years, especially for spring events. Climate during previous weeks to phenophases occurrence had the greatest impact on plants, although all events were also affected by climate conditions several months before. Immediate along with delayed climate effects suggest dual triggers in plant phenology. Climatic models accounted for more than 80% of variability in flowering and leaf unfolding dates, and in length of the growing season, but for lower proportions in fruiting and leaf falling. Most part of year‐to‐year changes in dates was accounted for temperature, while precipitation and NAO accounted for <10% of dates' variability. In the case of flowering, insect‐pollinated species were better modelled by climate than wind‐pollinated species. Differences in temporal responses of plant phenology to recent climate change are due to differences in the sensitivity to climate among events and species. Spring events are changing more than autumn events as they are more sensitive to climate and are also undergoing the greatest alterations of climate relative to other seasons. In conclusion, climate change has shifted plant phenology in the Mediterranean region.     

The influence of local spring temperature variance on temperature sensitivity of spring phenology

The impact of climate warming on the advancement of plant spring phenology has been heavily investigated over the last decade and there exists great variability among plants in their phenological sensitivity to temperature. However, few studies have explicitly linked phenological sensitivity to local climate variance. Here, we set out to test the hypothesis that the strength of phenological sensitivity declines with increased local spring temperature variance, by synthesizing results across ground observations. We assemble ground‐based long‐term (20–50 years) spring phenology database (PEP725 database) and the corresponding climate dataset. We find a prevalent decline in the strength of phenological sensitivity with increasing local spring temperature variance at the species level from ground observations. It suggests that plants might be less likely to track climatic warming at locations with larger local spring temperature variance. This might be related to the possibility that the frost risk could be higher in a larger local spring temperature variance and plants adapt to avoid this risk by relying more on other cues (e.g., high chill requirements, photoperiod) for spring phenology, thus suppressing phenological responses to spring warming. This study illuminates that local spring temperature variance is an understudied source in the study of phenological sensitivity and highlight the necessity of incorporating this factor to improve the predictability of plant responses to anthropogenic climate change in future studies.     

Species-level phenological responses to ‘global warming’ as evidenced by herbarium collections in the Tibetan Autonomous Region

In recent years attention has been given to assess the impacts of warming on the plant flowering phenology. There is a growing realization that herbarium-based collections could offer a reliable and relatively time-saving baseline data source to identify these effects. This article examines the magnitude and trends of warming effects on the average flowering timing (AFT) of plants in Tibet Autonomous Region using analysis of herbarium specimens collected for 4 decades. Mixed model with randomized blocks was used to analyze a set of 41 species (total 909 specimens) which were collected during the period of 1961–2000. Results showed that an earlier AFT emerged within 40 years period in comparison to the recorded data of the year of 2000 (0.5 days per year), and that 7.5 days early flowering was contributed by mean summer (i.e., June–August) temperature. It is proposed that temporary shifts in flowering phenology responding to continuing temperature rise could quantify the extent to which climate affects plant species. Analysis of well recorded herbarium specimens could provide a reasonable indication on the impacts of rising temperature on plant phenology. The result of this study could also facilitate a bridge between the scientific knowledge and indigenous knowledge of Tibetan communities.     

Prediction of Arctic plant phenological sensitivity to climate change from historical records

The pace of climate change in the Arctic is dramatic, with temperatures rising at a rate double the global average. The timing of flowering and fruiting (phenology) is often temperature dependent and tends to advance as the climate warms. Herbarium specimens, photographs, and field observations can provide historical phenology records and have been used, on a localised scale, to predict species’ phenological sensitivity to climate change. Conducting similar localised studies in the Canadian Arctic, however, poses a challenge where the collection of herbarium specimens, photographs, and field observations have been temporally and spatially sporadic. We used flowering and seed dispersal times of 23 Arctic species from herbarium specimens, photographs, and field observations collected from across the 2.1 million km² area of Nunavut, Canada, to determine (1) which monthly temperatures influence flowering and seed dispersal times; (2) species’ phenological sensitivity to temperature; and (3) whether flowering or seed dispersal times have advanced over the past 120 years. We tested this at different spatial scales and compared the sensitivity in different regions of Nunavut. Broadly speaking, this research serves as a proof of concept to assess whether phenology–climate change studies using historic data can be conducted at large spatial scales. Flowering times and seed dispersal time were most strongly correlated with June and July temperatures, respectively. Seed dispersal times have advanced at double the rate of flowering times over the past 120 years, reflecting greater late‐summer temperature rises in Nunavut. There is great diversity in the flowering time sensitivity to temperature of Arctic plant species, suggesting climate change implications for Arctic ecological communities, including altered community composition, competition, and pollinator interactions. Intraspecific temperature sensitivity and warming trends varied markedly across Nunavut and could result in greater changes in some parts of Nunavut than in others.     

Temperature effects on forest herbs assessed by warming and transplant experiments along a latitudinal gradient

Slow‐colonizing forest understorey plants are probably not able to rapidly adjust their distribution range following large‐scale climate change. Therefore, the acclimation potential to climate change within their actual occupied habitats will likely be key for their short‐ and long‐term persistence. We combined transplant experiments along a latitudinal gradient with open‐top chambers to assess the effects of temperature on phenology, growth and reproductive performance of multiple populations of slow‐colonizing understorey plants, using the spring flowering geophytic forb Anemone nemorosa and the early summer flowering grass Milium effusum as study species. In both species, emergence time and start of flowering clearly advanced with increasing temperatures. Vegetative growth (plant height, aboveground biomass) and reproductive success (seed mass, seed germination and germinable seed output) of A. nemorosa benefited from higher temperatures. Climate warming may thus increase future competitive ability and colonization rates of this species. Apart from the effects on phenology, growth and reproductive performance of M. effusum generally decreased when transplanted southwards (e.g., plant size and number of individuals decreased towards the south) and was probably more limited by light availability in the south. Specific leaf area of both species increased when transplanted southwards, but decreased with open‐top chamber installation in A. nemorosa. In general, individuals of both species transplanted at the home site performed best, suggesting local adaptation. We conclude that contrasting understorey plants may display divergent plasticity in response to changing temperatures which may alter future understorey community dynamics.     

Temperature alone does not explain phenological variation of diverse temperate plants under experimental warming

Anthropogenic climate change has altered temperate forest phenology, but how these trends will play out in the future is controversial. We measured the effect of experimental warming of 0.6–5.0 °C on the phenology of a diverse suite of 11 plant species in the deciduous forest understory (Duke Forest, North Carolina, USA) in a relatively warm year (2011) and a colder year (2013). Our primary goal was to dissect how temperature affects timing of spring budburst, flowering, and autumn leaf coloring for functional groups with different growth habits, phenological niches, and xylem anatomy. Warming advanced budburst of six deciduous woody species by 5–15 days and delayed leaf coloring by 18–21 days, resulting in an extension of the growing season by as much as 20–29 days. Spring temperature accumulation was strongly correlated with budburst date, but temperature alone cannot explain the diverse budburst responses observed among plant functional types. Ring‐porous trees showed a consistent temperature response pattern across years, suggesting these species are sensitive to photoperiod. Conversely, diffuse‐porous species responded differently between years, suggesting winter chilling may be more important in regulating budburst. Budburst of the ring‐porous Quercus alba responded nonlinearly to warming, suggesting evolutionary constraints may limit changes in phenology, and therefore productivity, in the future. Warming caused a divergence in flowering times among species in the forest community, resulting in a longer flowering season by 10‐16 days. Temperature was a good predictor of flowering for only four of the seven species studied here. Observations of interannual temperature variability overpredicted flowering responses in spring‐blooming species, relative to our warming experiment, and did not consistently predict even the direction of flowering shifts. Experiments that push temperatures beyond historic variation are indispensable for improving predictions of future changes in phenology.     

近五十年北京板栗始花物候对光合有效辐射变化的响应

与全球范围内气候变暖对植物物候影响研究相比,其他气候因素（如光合有效辐射PAR等）对物候影响报道较少,果树花期物候对光合有效辐射变化响应的研究更是未见报道。本研究以1963—2008年间北京板栗始花物候资料及相应的日光合有效辐射数据为基础,利用偏最小二乘回归法确定了PAR影响板栗始花物候的两个关键阶段,进而分析了两阶段内PAR、温度及相对湿度变化对板栗花期的具体影响。结果表明,北京过去50年两相关阶段内PAR呈显著下降趋势,其中9月24日至次年2月5日问PAR下降对板栗花期提前具有促进作用,可解释12％的花期提前趋势;2月6日至次年5月31日间PAR下降促使花期延迟,但未达显著水平（P〉0．1）。板栗花期提前主要与2月6日至次年5月31日间温度升高有关,其间温度变化可解释41％的花期提前趋势;其次是相对湿度,PAR变化对花期影响较小。鉴于PAR、温度及相对湿度间的互作效应,PAR和相对湿度对花期物候的影响可由温度效应加以解释。     

Response of Chestnut Flowering in Beijing to Photosynthetically Active Radiation Variation and Change in Recent Fifty Years

Climate warming has affected plant phenology throughout the world, but few studies have evaluated plant phenology response to other climate factors (eg. photosynthetically active radiation PAR). In particular, the response of fruit flowering to PAR variation has not been explored yet. Long term (1963-2008) of chestnut (Castanea mollissima Blume) first flowering dates from Beijing, China were related with daily PAR for the 12 months, using Partial Least Squares (PLS) regression analysis. Two relevant phases were identified, during which mean PAR, temperature, and relative humidity (RH) were correlated with flowering dates, respectively. PAR during the both relevant periods decreased significantly in Beijing over the past 50 years. Reduced PAR during 24 September 5 February showed an advance impact on chestnut flowering, and could explain 12% of advance trend in flowering timing. Deceased PAR during 6 February 31 May had a delayed effect on tree flowering, but it was not significant enough to reject the null hypothesis of no impact over time. Advanced flowering of chestnut was mainly determined by increasing temperature between 6 February and 31 May which could explain 41% of flowering trend. Relative humidity variation during this period played secondly important role on tree flowering. Considering the interaction among these three climate factors, the impacts of PAR and RH on flowering timing could partially be attributed to the effects of temperature variation.     

Flowering phenology change and climate warming in southwestern Ohio

Global surface temperature has increased markedly over the last 100 years. This increase has a variety of implications for human societies, and for ecological systems. One of the most obvious ways ecosystems are affected by global climate change is through alteration of organisms’ developmental timing (phenology). We used annual botanical surveys that documented the first flowering for an array of species from 1976 to 2003 to examine the potential implications of climate change for plant development. The overall trend for these species was a progressively earlier flowering time. The two earliest flowering taxa (Galanthus and Crocus) also exhibited the strongest shift in first flowering. We detected a significant trend in climate suggesting higher temperatures in winter and spring over the sampling interval and found a significant relationship between warming temperatures and first flowering time for some species. Although 60% of the species in our study flowered earlier over the sampling interval, the remaining species exhibited no statistically detectable change. This variation in response is ostensibly associated with among-species variation in the role of climate cues in plant development. Future work is needed to isolate specific climate cues, and to link plant phenology to the physiological processes that trigger plant development.     

Variable flowering phenology and pollinator use in a community suggest future phenological mismatch

Recent anthropogenic climate change is strongly associated with average shifts toward earlier seasonal timing of activity (phenology) in temperate-zone species. Shifts in phenology have the potential to alter ecological interactions, to the detriment of one or more interacting species. Recent models predict that detrimental phenological mismatch may increasingly occur between plants and their pollinators. One way to test this prediction is to examine data from ecological communities that experience large annual weather fluctuations. Taking this approach, we analyzed interactions over a four-year period among 132 plant species and 665 pollinating insect species within a Mediterranean community. For each plant species we recorded onset and duration of flowering and number of pollinator species. Flowering onset varied among years, and a year of earlier flowering of a species tended to be a year of fewer species pollinating its flowers. This relationship was attributable principally to early-flowering species, suggesting that shifts toward earlier phenology driven by climate change may reduce pollination services due to phenological mismatch. Earlier flowering onset of a species also was associated with prolonged flowering duration, but it is not certain that this will counterbalance any negative effects of lower pollinator species richness on plant reproductive success. Among plants with different life histories, annuals were more severely affected by flowering–pollinator mismatches than perennials. Specialized plant species (those attracting a smaller number of pollinator species) did not experience disproportionate interannual fluctuations in phenology. Thus they do not appear to be faced with disproportionate fluctuations in pollinator species richness, contrary to the expectation that specialists are at greatest risk of losing mutualistic interactions because of climate change.     

Reproductive limits of a late-flowering high-mountain Mediterranean plant along an elevational climate gradient

Mountain plants are particularly sensitive to climate warming because snowmelt timing exerts a direct control on their reproduction. Current warming is leading to earlier snowmelt dates and longer snow-free periods. Our hypothesis is that high-mountain Mediterranean plants are not able to take advantage of a lengthened snow-free period because this leads to longer drought that truncates the growing season. However, reproductive timing may somewhat mitigate these negative effects through temporal shifts. We assessed the effects of flowering phenology on the reproductive success of Silene ciliata, a Mediterranean high-mountain plant, across an altitudinal gradient during two climatically contrasting years. The species showed a late-flowering pattern hampering the use of snowmelt water. Plant fitness was largely explained by the elapsed time from snowmelt to onset of flowering, suggesting a selective pressure towards early flowering caused by soil moisture depletion. The proportion of flowering plants decreased at the lowest population, especially in the drier year. Plants produced more flowers, fruits and seeds at the highest population and in the mild year. Our results indicate that water deficit in dry years could threaten the lowland populations of this mountainous species, while high-altitude environments are more stable over time.     

Phenological Sensitivity of Early and Late Flowering Species Under Seasonal Warming and Altered Precipitation in a Seminatural Temperate Grassland Ecosystem

Shifts in flowering phenology of plants are indicators of climate change. The great majority of existing phenological studies refer solely to gradual warming. However, knowledge on how flowering phenology responds to changes in seasonal variation of warming and precipitation regimes is missing. We report the onset of 22 early (flowering before/within May) and 23 late flowering (flowering after May) species in response to manipulated seasonal warming (equal to + 1.2°C; last 100-year summer/winter warming), additional winter rainfall, and modified precipitation variability (including a 1000-year extreme drought event followed by heavy rainfall) over the growing season in two consecutive years for a species-rich temperate grassland ecosystem. The average onset of flowering (over 2 years) was significantly advanced 3.1 days by winter warming and 1.5 days by summer warming compared to control. Early flowering species responded to seasonal warming in both years, while late-flowering species responded in only 1 year to summer warming. The average onset of early flowering species was significantly advanced, 4.9 days by winter warming and 2.3 days by summer warming. Species-specific analysis showed that even within the early flowering community there were divergences. A positive correlation between plant height and shift in flowering onset was detected under winter warming (R² = 0.20, p = 0.005). The average onsets of early and late flowering community were affected by neither winter rain nor growing season precipitation variability. Seasonal differences in warming, and particularly winter warming, might alter community dynamics among early and late flowering species which can cause shifts in the seasonal performances of temperate ecosystems.     

Selection on flowering time in Mediterranean high-mountain plants under global warming

Under climate warming, plants will undergo novel selective pressures to adjust reproductive timing. Adjustment between reproductive phenology and environment is expected to be higher in arctic and alpine habitats because the growing season is considerably short. As early- and late-flowering species reproduce under very different environmental conditions, selective pressures on flowering phenology and potential effects of climate change are likely to differ between them. However, there is no agreement on the magnitude of the benefits and costs of early- vs. late-flowering species under a global warming scenario. In spite of its relevance, phenotypic selection on flowering phenology has rarely been explored in alpine plants and never in Mediterranean high mountain species, where selective pressures are very different due to the summer drought imposed over the short growth season. We hypothesized that late-flowering plants in Mediterranean mountains should present stronger selective pressures towards early onset of reproduction than early-flowering species, because less water is available in the soil as growing season progresses. We performed selection analyses on flowering onset and duration in two high mountain species of contrasting phenology. Since phenotypic selection can be highly context-dependent, we studied several populations of each species for 2 years, covering their local altitudinal ranges and their different microhabitats. Surrogates of biotic selective agents, like fruitset for pollinators and flower and fruit loss for flower and seed predators, were included in the analysis. Differences between the early- and the late-flowering species were less than expected. A consistent negative correlational selection of flowering onset and duration was found affecting plant fitness, i.e., plants that bloomed earlier flowered for longer periods improving plant fitness. Nevertheless, the late-flowering species may experience higher risks under climate warming because in extremely warm and dry years the earlier season does not bring about a longer flowering duration due to summer drought.     

Greater temperature sensitivity of plant phenology at colder sites: implications for convergence across northern latitudes

Warmer temperatures are accelerating the phenology of organisms around the world. Temperature sensitivity of phenology might be greater in colder, higher latitude sites than in warmer regions, in part because small changes in temperature constitute greater relative changes in thermal balance at colder sites. To test this hypothesis, we examined up to 20 years of phenology data for 47 tundra plant species at 18 high‐latitude sites along a climatic gradient. Across all species, the timing of leaf emergence and flowering was more sensitive to a given increase in summer temperature at colder than warmer high‐latitude locations. A similar pattern was seen over time for the flowering phenology of a widespread species, Cassiope tetragona. These are among the first results highlighting differential phenological responses of plants across a climatic gradient and suggest the possibility of convergence in flowering times and therefore an increase in gene flow across latitudes as the climate warms.     

Consequences of preformation for dynamic resource allocation by a carnivorous herb,Pinguicula vulgaris (Lentibulariaceae)

When resource availability changes frequently and unpredictably, natural selection favors flexible resource allocation; however, such versatility may be compromised in perennial plants that differentiate leaves or flowers a year in advance of their development (preformation). We investigated resource allocation by the carnivorous perennial Pinguicula vulgaris to determine whether increased resource availability changes within-season allocation to growth, vegetative propagation, and reproduction. In response to resource supplementation (feeding with fruit flies), plants attained a mass 60% greater than that of unfed plants after a single growing season. Feeding also enhanced vegetative propagation, which is closely associated with growth, without modifying relations between these two vegetative functions. In contrast, feeding did not alter the size of vegetative rosettes or the within-season incidence of either flowering or fruiting. This lack of immediate responses occurred because floral and leaf primordia differentiated up to 10 mo before resource supplementation and flower development. However, enhanced resource status likely affected future reproduction indirectly through resource effects on plant size. Large plants produced more floral primordia and between-year changes in fruiting status corresponded to changes in plant size. These results illustrate that preformation can delay responses to enhanced resources by perennial plants.     

How does climate warming affect plant‐pollinator interactions?

Climate warming affects the phenology, local abundance and large-scale distribution of plants and pollinators. Despite this, there is still limited knowledge of how elevated temperatures affect plant-pollinator mutualisms and how changed availability of mutualistic partners influences the persistence of interacting species. Here we review the evidence of climate warming effects on plants and pollinators and discuss how their interactions may be affected by increased temperatures. The onset of flowering in plants and first appearance dates of pollinators in several cases appear to advance linearly in response to recent temperature increases. Phenological responses to climate warming may therefore occur at parallel magnitudes in plants and pollinators, although considerable variation in responses across species should be expected. Despite the overall similarities in responses, a few studies have shown that climate warming may generate temporal mismatches among the mutualistic partners. Mismatches in pollination interactions are still rarely explored and their demographic consequences are largely unknown. Studies on multi-species plant-pollinator assemblages indicate that the overall structure of pollination networks probably are robust against perturbations caused by climate warming. We suggest potential ways of studying warming-caused mismatches and their consequences for plant-pollinator interactions, and highlight the strengths and limitations of such approaches.     

Phenology in a warming world: differences between native and non‐native plant species

Phenology is a harbinger of climate change, with many species advancing flowering in response to rising temperatures. However, there is tremendous variation among species in phenological response to warming, and any phenological differences between native and non‐native species may influence invasion outcomes under global warming. We simulated global warming in the field and found that non‐native species flowered earlier and were more phenologically plastic to temperature than natives, which did not accelerate flowering in response to warming. Non‐native species' flowering also became more synchronous with other community members under warming. Earlier flowering was associated with greater geographic spread of non‐native species, implicating phenology as a potential trait associated with the successful establishment of non‐native species across large geographic regions. Such phenological differences in both timing and plasticity between native and non‐natives are hypothesised to promote invasion success and population persistence, potentially benefiting non‐native over native species under climate change.     

Limited effects of early snowmelt on plants,decomposers, and soil nutrients in Arctic tundra soils

In addition to warming temperatures, Arctic ecosystems are responding to climate change with earlier snowmelt and soil thaw. Earlier snowmelt has been examined infrequently in field experiments, and we lack a comprehensive look at belowground responses of the soil biogeochemical system that includes plant roots, decomposers, and soil nutrients. We experimentally advanced the timing of snowmelt in factorial combination with an open‐top chamber warming treatment over a 3‐year period and evaluated the responses of decomposers and nutrient cycling processes. We tested two alternative hypotheses: (a) Early snowmelt and warming advance the timing of root growth and nutrient uptake, altering the timing of microbial and invertebrate activity and key nutrient cycling events; and (b) loss of insulating snow cover damages plants, leading to reductions in root growth and altered biological activity. During the 3 years of our study (2010–2012), we advanced snowmelt by 4, 15, and 10 days, respectively. Despite advancing aboveground plant phenology, particularly in the year with the warmest early‐season temperatures (2012), belowground effects were primarily seen only on the first sampling date of the season or restricted to particular years or soil type. Overall, consistent and substantial responses to early snowmelt were not observed, counter to both of our hypotheses. The data on soil physical conditions, as well interannual comparisons of our results, suggest that this limited response was because of the earlier date of snowmelt that did not coincide with substantially warmer air and soil temperatures as they might in response to a natural climate event. We conclude that the interaction of snowmelt timing with soil temperatures is important to how the ecosystem will respond, but that 1‐ to 2‐week changes in timing of snowmelt alone are not enough to drive season‐long changes in soil microbial and nutrient cycling processes.