Plant phenological data and tree-rings as palaeoclimate indicators in south-west Finland since AD 1750

Plant phenological data and tree-rings were tested for their palaeoclimatic value in south-west Finland since AD 1750. The information from fragmentary, partly overlapping, partly non-systematically biased plant phenological records of 14 different phenomena (a total of 3,144 observations) was combined into one continuous time series of phenological indices. All site- and phenomenon-specific series were standardized to present an average of zero and standard deviation of one. The mean phenomenon-specific series were then averaged as arithmetic means for annually resolved time series representing the variability in the particular plant phenomenon. Consequently, each phenomenon-specific mean series was based on spatially normalized site-specific index series. These series were compared to each other, living-tree and subfossil tree-rings, and to early and modern meteorological time series. Phenological indices showed strong positive correlation with February to June temperatures. On the other hand, the correlations between phenological indices and precipitation data were around zero. Analysis using time-dependent running correlations showed non-stationary relationship between the tree-rings and phenological indices and observed spring temperatures. The skill of phenological data for reconstructing the spring temperatures was statistically proved.     

Changes in temperature sensitivity of spring phenology with recent climate warming in Switzerland are related to shifts of the preseason

The spring phenology of plants in temperate regions strongly responds to spring temperatures. Climate warming has caused substantial phenological advances in the past, but trends to be expected in the future are uncertain. A simple indicator is temperature sensitivity, the phenological advance statistically associated with a 1°C warmer mean temperature during the “preseason”, defined as the most temperature‐sensitive period preceding the phenological event. Recent analyses of phenological records have shown a decline in temperature sensitivity of leaf unfolding, but underlying mechanisms were not clear. Here, we propose that climate warming can reduce temperature sensitivity simply by reducing the length of the preseason due to faster bud development during this time period, unless the entire preseason shifts forward so that its temperature does not change. We derive these predictions theoretically from the widely used “thermal time model” for bud development and test them using data for 19 phenological events recorded in 1970–2012 at 108 stations spanning a 1600 m altitudinal range in Switzerland. We consider how temperature sensitivity, preseason start, preseason length and preseason temperature change (i) with altitude, (ii) between the periods 1970–1987 and 1995–2012, which differed mainly in spring temperatures, and (iii) between two non‐consecutive sets of 18 years that differed mainly in winter temperatures. On average, temperature sensitivity increased with altitude (colder climate) and was reduced in years with warmer springs, but not in years with warmer winters. These trends also varied among species. Decreasing temperature sensitivity in warmer springs was associated with a limited forward shift of preseason start, higher temperatures during the preseason and reduced preseason length, but not with reduced winter chilling. Our results imply that declining temperature sensitivity can result directly from spring warming and does not necessarily indicate altered physiological responses or stronger constraints such as reduced winter chilling.     

Changes in phenology of the locust tree (Robinia pseudoacacia L.) in Hungary

 Intense research is being carried out on climate variability and change and the estimation and detection of anthropogenic effects. In addition to statistical methods, the use of plants, as biological indicators is becoming more popular as they are sensitive to environmental conditions. In this article we compare maps of the flowering dates of the locust tree (Robinia pseudoacacia L.) for three different time intervals between 1851 and 1994. The maps revealed noticeable shifts of dates, of approximately 3–8 days, towards earlier flowering. This change is related to the average temperature of spring (15 March–15 May), via a simple statistical model that is accurate enough to be able to quantify phenological changes and to calculate the corresponding warming. The model developed can estimate spring mean temperature using phenological data from R. pseudoacacia L. with an accuracy of 0.2° C. Estimates of mean temperature based on phenological changes are compared to climatic series. This comparison emphasizes the possibility of using R. pseudoacacia. L. as a bio-indicator. Estimates of temperature changes are also given. Received: 5 August 1996 / Revised: 14 April 1997 / Accepted: 11 November 1997     

Trends in phenology of <Emphasis Type="Italic">Betula pubescens</Emphasis> across the boreal zone in Finland

Timing of plant phenophases is a useful biological indicator which shows how nature responds to the variation in climate. Thus, long phenological observation series help to estimate the impact of changing climate on forest plants. We investigated whether phenological patterns of downy birch Betula pubescens respond to warming climate and whether the intensity of the responses varies among phytogeographical zones. We studied data collected by the Finnish National Phenological Network from 30 observation sites across Finland during 1997–2006. The advancement in the timing of the earliest phenophase, bud burst, ranged from 0.7 days/year in southern boreal zone to 1.4 days/year in middle and northern boreal zones. Timing of bud burst was most clearly dependent on mean May temperatures. The intensity of the response to temperature increased from south to north. The advancement of bud burst resulted into a significant lengthening of the growth period by 1.2–1.6 days per year in northern and middle boreal zones, respectively, whereas the lengthening was not significant in the southern boreal zone. No trend was observed in the timing of autumn phenophases.     

中国东部温带植被生长季节的空间外推估计

利用地面植物物候和遥感归一化差值植被指数（NDVI）数据,以及一种物候-遥感外推方法,实现植被生长季节从少数站点到较多站点的空间外推。结果表明：（1）在1982～1993年期间,中国东部温带地区植被生长季节多年平均起讫日期的空间格局与春季和秋季平均气温的空间格局相关显著;（2）在不同纬度带和整个研究区域,植被生长季节结束日期呈显著推迟的趋势,而开始日期则呈不显著提前的趋势,这与欧洲和北美地区植被生长季节开始日期显著提前而结束日期不显著推迟的变化趋势完全不同;（3）北部纬度带的植被生长季节平均每年延长1．4～3．6d,全区的植被生长季节平均每年延长1．4d,与同期北半球和欧亚大陆植被生长季节延长的趋势数值相近;（4）植被生长季节结束日期的显著推迟与晚春至夏季的区域性降温有关,而植被生长季节开始日期的不显著提前则与晚冬至春季气温趋势的不稳定变化有关;（5）在年际变化方面,植被生长季节开始和结束日期分别与2～4月份平均气温和5～6月份平均气温呈负相关关系。     

Interannual phenological variability in two North-East Atlantic populations of Calanus finmarchicus

Phenological variations of the marine copepod Calanus finmarchicus were studied in Svalbard and northern Iceland, where samples were collected in summer and spring, respectively, over two decades. Four phenological indices, developed for copepodite stage-structured data, were used: the proportion of CV to total abundance (CVT), the population development index (PDI), the average weighted stage (AWS), and the average age in days (AAD). The variation of these indices was compared within and between locations to evaluate their suitability for the analysis of phenological effects. For both populations, phenology was related to local temperature and spring bloom dynamics, influenced by Atlantic water inflow. Large-scale climate was related to phenological variation only in the Svalbard population. C. finmarchicus phenology advanced under warmer conditions in both locations. We conclude that vertical phenological indices, i.e. based on interannual changes in copepodite stage structure, are useful to investigate zooplankton phenology, especially when data series covering the whole life cycle are unavailable. We suggest that AWS and AAD can be applied irrespective of sampling time, while PDI and CVT should be applied for early and late sampling seasons, respectively. When multiple phenological indices are needed, AAD in combination with either CVT or PDI should be preferred.     

Lagged effects of North Atlantic Oscillation on spittlebug Philaenus spumarius (Homoptera) abundance and survival

The North Atlantic Oscillation (NAO) is a large‐scale pattern of climate variability that has been shown to have important ecological effects on a wide spectrum of taxa. Studies on terrestrial invertebrates are, however, lacking. We studied climate‐connected causes of changes in population sizes in island populations of the spittlebug Philaenus spumarius (L.) (Homoptera). Three populations living in meadows on small Baltic Sea islands were investigated during the years 1970–2005 in Tvärminne archipelago, southern Finland. A separate analysis was done on the effects of NAO and local climate variables on spittlebug survival in 1969–1978, for which survival data existed for two islands. We studied survival at two stages of the life cycle: growth rate from females to next year's instars (probably mostly related to overwintering egg survival), and survival from third instar stage to adult. The latter is connected to mortality caused by desiccation of plants and spittle masses. Higher winter NAO values were consistently associated with smaller population sizes on all three islands. Local climate variables entering the most parsimonious autoregressive models of population abundance were April and May mean temperature, May precipitation, an index of May humidity, and mean temperature of the coldest month of the previous winter. High winter NAO values had a clear negative effect on late instar survival in 1969–1978. Even May–June humidity and mean temperature of the coldest month were associated with late instar survival. The climate variables studied (including NAO) had no effect on the growth rate from females to next year's instars. NAO probably affected the populations primarily in late spring. Cold and snowy winters contribute to later snow melt and greater spring humidity in the meadows. We show that winter NAO has a considerable lagged effect on April and May temperature; even this second lagged effect contributes to differences in humidity. The lagged effect of the winter NAO to spring temperatures covers a large area in northern Europe and has been relatively stationary for 100 years at least in the Baltic area.     

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.     

Spatial and temporal variation of phenological growing season and climate change impacts in temperate eastern China

Using phenological and normalized difference vegetation index (NDVI) data from 1982 to 1993 at seven sample stations in temperate eastern China, we calculated the cumulative frequency of leaf unfolding and leaf coloration dates for deciduous species every 5 days throughout the study period. Then, we determined the growing season beginning and end dates by computing times when 50% of the species had undergone leaf unfolding and leaf coloration for each station year. Next, we used these beginning and end dates of the growing season as time markers to determine corresponding threshold NDVI values on NDVI curves for the pixels overlaying phenological stations. Based on a cluster analysis, we determined extrapolation areas for each phenological station in every year, and then implemented the spatial extrapolation of growing season parameters from the seven sample stations to all possible meteorological stations in the study area. Results show that spatial patterns of growing season beginning and end dates correlate significantly with spatial patterns of mean air temperatures in spring and autumn, respectively. Contrasting with results from similar studies in Europe and North America, our study suggests that there is a significant delay in leaf coloration dates, along with a less pronounced advance of leaf unfolding dates in different latitudinal zones and the whole area from 1982 to 1993. The growing season has been extended by 1.4–3.6 days per year in the northern zones and by 1.4 days per year across the entire study area on average. The apparent delay in growing season end dates is associated with regional cooling from late spring to summer, while the insignificant advancement in beginning dates corresponds to inconsistent temperature trend changes from late winter to spring. On an interannual basis, growing season beginning and end dates correlate negatively with mean air temperatures from February to April and from May to June, respectively.     

Altered geographic and temporal variability in phenology in response to climate change

Aim In response to recent climate warming, numerous studies have reported an earlier onset of spring and, to a lesser degree, a later onset of autumn, both determined from phenological observations. Here, we examine whether these reported changes have affected the synchronization of events on a regional level by examining temporal and spatial variability in phenology. In particular, we study whether years with earlier springs are associated with an altered spatial variability in phenology. Location Germany and the United Kingdom. Methods Plant phenological observations of 35 different phases (events such as flowering and leafing) collected by the German Weather Service (1951–2002) and butterfly phenological records of 29 species collected by the UK Butterfly Monitoring Scheme (1976–2003) are used. In these long‐term records, we examine the temporal (year‐to‐year) variability and the spatial (geographic or between site) variability with particular emphasis on how they vary with time of the year and with earliness or lateness of the phase. Results Early phenological events (i.e. spring) are more variable than later events, both in time and in space, although the pattern is clearer for plants than for butterflies. Confirming previous results, we find a clear relationship between the mean date of spring and summer phases and the degree to which they have become earlier. The spatial variability of spring events is greater in warmer years that have faster plant development. However, late spring and summer events do not show a consistent relationship. Autumn events are somewhat more spatially variable in years characterized by later seasons. Main conclusions This is the first examination of spatial variability of plant and animal phenological events at a multinational scale. Earlier spring events are likely to be associated with increased spatial variability in plants, although this is unlikely to also be true for summer events. If species experience differential changes in geographic variation this may disrupt interactions among them, e.g. in food webs. On the other hand, these may offer advantages for mobile species. Further research on linked species is recommended.     

Morphological constraints on changing avian migration phenology

Many organisms at northern latitudes have responded to climate warming by advancing their spring phenology. Birds are known to show earlier timing of spring migration and reproduction in response to warmer springs. However, species show heterogeneous phenological responses to climate warming, with those that have not advanced or have delayed migration phenology experiencing population declines. Although some traits (such as migration distance) partly explain heterogeneity in phenological responses, the factors affecting interspecies differences in the responsiveness to climate warming have yet to be fully explored. In this comparative study, we investigate whether variation in wing aspect ratio (reflecting relative wing narrowness), an ecomorphological trait that is strongly associated with flight efficiency and migratory behaviour, affects the ability to advance timing of spring migration during 1960–2006 in a set of 80 European migratory bird species. Species with larger aspect ratio (longer and narrower wings) showed smaller advancement of timing of spring migration compared to species with smaller aspect ratio (shorter and wider wings) while controlling for phylogeny, migration distance and other life‐history traits. In turn, migration distance positively predicted aspect ratio across species. Hence, species that are better adapted to migration appear to be more constrained in responding phenologically to rapid climate warming by advancing timing of spring migration. Our findings corroborate the idea that aspect ratio is a major evolutionary correlate of migration, and suggest that selection for energetically efficient flights, as reflected by high aspect ratio, may hinder phenotypically plastic/microevolutionary adjustments of migration phenology to ongoing climatic changes.     

Regional and local drivers of macroinvertebrate assemblages in boreal springs

Aim To identify the most important environmental drivers of benthic macroinvertebrate assemblages in boreal springs at different spatial scales, and to assess how well benthic assemblages correspond to terrestrially derived ecoregions. Location Finland. Methods Benthic invertebrates were sampled from 153 springs across four boreal ecoregions of Finland, and these data were used to analyse patterns in assemblage variation in relation to environmental factors. Species data were classified using hierarchical divisive clustering (twinspan ) and ordinated using non‐metric multidimensional scaling. The prediction success of the species and environmental data into a priori (ecoregions) and a posteriori (twinspan ) groups was compared using discriminant function analysis. Indicator species analysis was used to identify indicator taxa for both a priori and a posteriori assemblage types. Results The main patterns in assemblage clusters were related to large‐scale geographical variation in temperature. A secondary gradient in species data reflected variation in local habitat structure, particularly abundance of minerogenic spring brooks. Water chemistry variables were only weakly related to assemblage variation. Several indicator species representing southern faunistic elements in boreal springs were identified. Discriminant function analysis showed poorer success in classifying sites into ecoregions based on environmental than on species data. Similarly, when classifying springs into the twinspan groups, classification based on species data vastly outperformed that based on environmental data. Main conclusions A latitudinal zonation pattern of spring assemblages driven by regional thermal conditions is documented, closely paralleling corresponding latitudinal patterns in both terrestrial and freshwater assemblages in Fennoscandia. The importance of local‐scale environmental variables increased with decreasing spatial extent. Ecoregions provide an initial stratification scheme for the bioassessment of benthic macroinvertebrates of North European springs. Our results imply that climate warming, landscape disturbance and degradation of spring habitat pose serious threats to spring biodiversity in northern Europe, especially to its already threatened southern faunistic elements.     

Breeding phenological response to spring weather conditions in common Finnish birds: resident species respond stronger than migratory species

National bird‐nest record schemes provide a valuable data source to study large‐scale changes in basic breeding biology and effects of climate change on birds. Using nest‐record scheme data from 26 common Finnish breeding bird species from whole Finland, we estimated the laydate of the first egg for 129 063 nesting attempts. We then investigated the relationship of mean spring temperature and spring precipitation sum to changes in the onset of laying over the period 1961–2012. In addition, we examine differences in response to these climatic variables for species grouped for different life history strategies; migration, diet and habitat. Finally, we test whether body size is related to the strength of phenological response. We show that 26 common Finnish breeding bird species have advanced their laying dates over time and to an increase in the mean spring temperature over the study period. When species are grouped according life history strategies, we find that breeding phenological change is negatively associated with changes in the mean spring temperature where residents respond strongest to changes in mean spring temperature, but also short‐ and long‐distance migrants advance laydates with increasing spring temperatures. Breeding phenological change is also associated with spring precipitation, where resident species delay and short‐distance migrants advance the onset of breeding. In addition we find that omnivorous species respond stronger than insectivorous species to changes in spring temperature. In contrast to results from an earlier study, we do not find evidence that small‐sized species respond stronger to spring temperature than large‐sized species. As climate warming is predicted to continue in the future, long‐term citizen science schemes, such as the Finnish nest‐card scheme, prove to be a valuable cost‐effective way to monitor the environment and allow investigation into how species are responding to changes in their environment.     

Remote sensing of larch phenological cycle and analysis of relationships with climate in the Alpine region

This research aims at developing a remote sensing technique for monitoring the interannual variability of the European larch phenological cycle in the Alpine region of Aosta Valley (Northern Italy) and to evaluate its relationships with climatic factors. Phenological field observations were conducted in eight test sites from 2005 to 2007 to determine the dates of completion of different phenological phases. MODerate Resolution Imaging Spectrometer (MODIS) 250 m 16‐days normalized difference vegetation index (NDVI) time series were fitted with double logistic curves and the dates corresponding to different features of the curves were determined. Comparison with field data showed that the features of the fitted NDVI curve that allowed the best estimate of the start and end of the growing season were the zeroes of its third derivative (MAE of 6 and 4 days, respectively). The start and end of season were also estimated with the spring warming (SW) and growing season index (GSI) phenological models. MODIS start and end of season dates generally agreed with those obtained by the SW and GSI climate‐driven phenological models. However, phenological models provided erroneous results when applied in years with anomalous meteorological conditions. The relationships between interannual variability of the larch phenological cycle and climate were investigated by comparing the mean start and end of season yearly anomalies with air temperature anomalies. A strong linear relationship (R²=0.91) was found between mean spring temperatures and mean start of season dates, with an increase of 1 °C in mean spring temperature leading to a 7‐day anticipation of mean larch bud‐burst date. Leaf coloring dates were found to be best related with mean September temperature (R²=0.77), but with higher spring temperatures appearing to lead to earlier leaf coloring.     

Natural history museum collections provide information on phenological change in British butterflies since the late-nineteenth century

Museum collections have the potential to provide valuable information on the phenological response of organisms to climate change. This is particularly useful for those species for which few data otherwise exist, but also to extend time series to the period before other observational data are available. To test this potential, we analysed data from 2,630 specimens of four species of British butterflies (Anthocharis cardamines, Hamearis lucina, Polyommatus bellargus and Pyrgus malvae), collected from 1876 to 1999 and stored in the Natural History Museum, London, UK (NHM). In A. cardamines, first-generation P. bellargus and P. malvae, we found that there was a strong significant negative relationship between spring temperature and 10th percentile collection dates, which approximates mean first appearance date, and median collection date, which approximates mean flight date. In all four species, there was a significant negative relationship between the 10th percentile collection date and the length of the collection period, which approximates flight period. In second-generation P. bellargus, these phenological measurements were correlated with summer temperature. We found that the rates of phenological response to temperature, based on NHM data, were similar to, or somewhat greater than, those reported for other organisms based on observational data covering the last 40 years. The lower rate of phenological response, and the significant influence of February rather than March or April temperatures, in recent decades compared with data from earlier in the twentieth century may indicate that early emerging British butterfly species are currently approaching the limits of phenological advancement in response to recent climate warming.     

Effects of decadal climate change on zooplankton over the last 50 years in the western subarctic North Pacific

Decadal‐ to multi‐decadal variations have been reported in many regional ecosystems in the North Pacific, resulting in an increasing demand to elucidate the link between long‐term climatic forcing and marine ecosystems. We detected phenological and quantitative changes in the copepod community in response to the decadal climatic variation in the western subarctic North Pacific by analyzing the extensive zooplankton collection taken since the 1950s, the Odate Collection. Copepod species were classified into five seasonal groups depending on the timing of the annual peak in abundance. The abundance of the spring community gradually increased for the period 1960–2002. The spring–summer community also showed an increasing trend in May, but a decadal oscillation pattern of quasi‐30‐year cycles in July. Phenological changes coincided with the climate regime shift in the mid‐1970s, indicated by the Pacific decadal oscillation index (PDO). After the regime shift, the timing of the peak abundance was delayed one month, from March–April to April–May, in the spring community, whereas it peaked earlier, from June–July to May–June, in the spring–summer community, resulting in an overlap of the high productivity period for the two communities in May. Wintertime cooling, followed by rapid summertime warming, was considered to be responsible for delayed initiation and early termination of the productive season after the mid‐1970s. Another phenological shift, quite different from the previous decade, was observed in the mid‐1990s, when warm winters followed by cool summers lengthened the productive season. The results suggest that climatic forcing with different decadal cycles may operate independently during winter–spring and spring–summer to create seasonal and interannual variations in hydrographic conditions; thus, combinations of these seasonal processes may determine the annual biological productivity.     

A 250-year index of first flowering dates and its response to temperature changes

Widespread concerns about global biodiversity loss have led to a growing demand for indices of biodiversity status. Today, climate change is among the most serious threats to global biodiversity. Although many studies have revealed phenological responses to climate change, no long-term community-level indices have been developed. We derived a 250-year index of first flowering dates for 405 plant species in the UK for assessing the impact of climate change on plant communities. The estimated community-level index in the most recent 25 years was 2.2–12.7 days earlier than any other consecutive 25-year period since 1760. The index was closely correlated with February–April mean Central England Temperature, with flowering 5.0 days earlier for every 1°C increase in temperature. The index was relatively sensitive to the number of species, not records per species, included in the model. Our results demonstrate how multi-species, multiple-site phenological events can be integrated to obtain indices showing trends for each species and across species. This index should play an important role in monitoring the impact of climate change on biodiversity. Furthermore, this approach can be extended to incorporate data from other taxa and countries for evaluating cross-taxa and cross-country phenological responses to climate change.     

西安木本植物物候与气候要素的关系

根据1963–2007年中国物候观测网西安观测站的物候和气温、降水资料,分析了西安站34种木本植物春季展叶始期、展叶盛期、始花期和盛花期等4个关键物候期的变化趋势、对气候变化的阶段响应特点及其与气温、降水变化的关系。结果表明,1963年以来,西安地区气温呈显著上升趋势,特别是1994年前后,气温发生明显突变,上升趋势更加明显;西安春季物候变化主要呈现提前趋势。在45年中,观测到的34种植物的展叶始期平均提前1天,展叶盛期平均提前1.4天,始花期平均提前9天,盛花期平均提前12天;以突变点为界,34个物种1995–2007年的4种物候期比1963–1994年平均提前了4.34±0.77天;春季物候期的早晚主要受春季气温的影响,特别是春季物候期发生当月和上一月的平均气温对物候期的影响最为显著。叶物候和物候发生期前一月的降水量有较为明显的相关关系,花物候期和降水的关系不明显。     

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.     

Climatic effects and phenological mismatch in cuckoo–host interactions: a role for host phenotypic plasticity in laying date?

Climatic effects on breeding phenology vary across organisms and therefore might promote a phenological mismatch in ecologically interacting species, including those engaged in coevolutionary interactions such as brood parasites and their hosts. Recent studies suggest that climatic induced changes in migration phenology may have mismatched cuckoos and their hosts in Europe. However, it is currently unknown whether cuckoo–host phenological mismatch results from different degrees of phenotypic plasticity or to different speeds of microevolutionary processes affecting hosts and parasites. Here we performed 1) cross‐sectional correlations between climate conditions and population level of phenological mismatch between the migratory brood parasite great spotted cuckoo Clamator glandarius and its main resident host in Europe, the magpie Pica pica; and 2) a longitudinal analysis to study within‐individual variation in breeding phenology for individual hosts experiencing different climate conditions over a period of nine years (2005–2013). Cross‐sectional analyses revealed independent and contrary effects of winter and spring temperature on magpie phenology: magpie hosts tend to breed earlier those years with lower February temperatures, however, high temperature in the first half of April spur individuals to lay eggs. Breeding phenology of cuckoos was tuned to that of their magpie host in time and duration. However, annual phenological mismatch between cuckoos and magpie hosts increased with NAO index and January temperature. Longitudinal analyses revealed high individual consistency in magpie host phenology, but a low influence of climate, suggesting that the climatic‐driven phenological mismatch between cuckoos and magpies at the population‐level cannot be explained by a host plastic response to climatic conditions.