Changes In Phenology Research Articles

Phenological divergence between plants and animals under climate change.

Climate change has altered the timing of recurring biological cycles in both plants and animals. Phenological changes may be unequal within and among trophic levels, potentially impacting the intricate interactions that regulate ecosystem functioning. Here we compile and analyse a global dataset of terrestrial phenological observations, including nearly half a million time series for both plants and animals. Our analysis reveals an increasing phenological asynchronization between plants and animals from 1981 to 2020, with a stronger overall advancement of late-season phenophases for plants than for animals. Almost 30% of temporal variations in plant phenophases can be explained by the timing of the preceding phenophases. This temporal dependency allows the advancement caused by warming to accumulate and propagate through seasons, advancing later phenophases more than earlier phases. By contrast, animals rely on various environmental cues and resource-tracking strategies to initiate their life-cycle activities, which weakens their cross-phenophase linkage and undermines the effect of warming. Our results suggest that future warming may increase phenological asynchronization between plants and animals and potentially disturb trophic interactions and ecosystem stability.

Study on the Response of Net Primary Productivity to Vegetation Phenology and Its Influencing Factors in Karst Ecologically Fragile Regions

Net primary productivity (NPP) is a crucial indicator of ecosystem function and sustainability. Quantifying the response of NPP to phenological dynamics is essential for understanding the impact of climate change on ecosystem processes. In this study, vegetation phenology data for Guizhou Province were extracted from the MCD12Q2 dataset, and NPP was estimated using the Normalized Difference Vegetation Index (NDVI) combined with meteorological data. Linear regression, trend analysis, and structural equation modeling were employed to clarify the spatiotemporal patterns of NPP and phenology as a basis for exploring the role of climatic factors in the NPP’s response to phenological changes. The results indicate that 72.15% of Guizhou Province shows an increasing trend in vegetation NPP (slope = 5.0981, p = 0.002). The start of the growing season (measured as SOS) tends to advance (slope = −0.4004, p = 0.0528), while the end of the growing season (measured as EOS) tends to delay (slope = 0.2747, p = 0.1011), resulting in an overall extension of the increasing length of the season (LOS) (slope = 0.64549, p = 0.0065). The spatiotemporal patterns of SOS, EOS, LOS, and NPP varied with elevation changes. For every 500 m increase in altitude, NPP decreased by 25.3 gC/m2, SOS was delayed by 7.1 days, EOS advanced by 1.25 days, and LOS decreased by 8.36 days. These findings suggest that the response of NPP to phenological changes is primarily controlled by local climatic and topographical conditions. Additionally, the indirect effects of climate on NPP through phenological changes were more significant than the direct effects. Climatic factors play varying roles in the NPP response to phenological dynamics, highlighting the profound influence of climate in regulating the mechanisms by which NPP responds to phenological changes.

Estimation of Forest Phenology’s Relationship with Age-Class Structure in Northeast China’s Temperate Deciduous Forests

Phenological changes in forests directly influence the spatiotemporal dynamics of carbon fixation and the carbon and water cycles in terrestrial ecosystems. Previous studies have shown that variations in biological factors (e.g., canopy height, leaf area, water use efficiency) can increase uncertainty in forest phenology, and these variations are closely linked to tree species and forest age-class structure. However, the interaction mechanisms through which tree species and forest age-class structure influence phenological changes remain insufficiently explored. In this study, phenological changes and their interactions and response mechanisms to different dominant tree species and forest age-class structures were analyzed via Sentinel-2 normalized difference vegetation index (NDVI) time series data from 2020 and 2021 across 480 typical deciduous forest plots in northeastern China. The results were as follows: (1) There were significant differences (p < 0.05) in the intra-annual phenological responses of temperate deciduous landscapes to the interaction between tree species and forest age-class structure. (2) The indirect effect of forest age-class structure through tree species on phenology exceeded the indirect effect of tree species through forest age-class structure, with a difference of 30.77%–35.09%. (3) When the dominant tree species and forest age-class structure were not distinguished, phenological differences in temperate forests ranged from 3 to 41 days and 2 to 23 days, respectively. This study highlights the differential impacts of key biological factors and their interactions on regional forest phenology, offering valuable insights into how these factors influence forest landscapes and providing a theoretical basis for improving forest management strategies.

A bitter cup of coffee? Assessing the impact of climate change on Arabica coffee production in Brazil

Brazil, the world's largest producer and exporter of Arabica coffee, faces increasing challenges from climate changes. To maintain the sustainability of this commodity, innovative management techniques will be essential. This study aimed to assess the impact of climate projections, considering two CMIP6 emission scenarios (SSP2–4.5 and SSP5–8.5) on the phenology and yield of Arabica coffee in 36 representative locations across Brazil for the periods 2041–2060, 2061–2080, and 2081–2100. Observed meteorological data from the BR-DWGD (Brazilian Daily Weather Gridded Data) and projected data from CLIMBra (Climate Change Dataset for Brazil) were employed. An agrometeorological model, calibrated for Brazilian conditions, estimated yield and phenology. Results indicate significant impacts on coffee cultivation areas, mainly due to rising temperatures and increased water deficits. Projections also suggest changes in coffee phenology, with anthesis advancing in colder regions and delaying in warmer areas, while maturation timing occurring earlier in all climates. Yield increases from CO₂ fertilization were more pronounced in category C climates (Cfa, Cfb, Cwa, and Cwb), particularly in Cwb climates, reaching 2.9 bags ha−1 (3.7 bags ha−1 with irrigation) under the SSP2–4.5 scenario and 2.5 bags ha−1 (3.5 bags ha−1 with irrigation) under SSP5–8.5. However, higher temperatures and water deficits could cause severe yield losses, especially in Aw climates and under high-emission scenarios, where losses may reach 100 %. Irrigation will play an important role in mitigating yield losses, especially in northern regions such as northern Minas Gerais and Bahia, where yields could exceed 30 bags ha−1. While southern Minas Gerais, São Paulo, and northern Paraná are projected to have the highest yields, these regions also face greater uncertainty and variability. This study underscores the need for adaptive agricultural practices, the development of resilient coffee cultivars, and supportive research policies to ensure the sustainability of coffee farming in the face of climate change.

Toward understanding grapevine responses to climate change: a multistress and holistic approach.

Recent research has extensively covered the effects of climate change factors, such as elevated CO2, rising temperatures and water deficit, on grapevine (Vitis spp.) biology. However, the assessment of the impacts of multiple climate change-related stresses on this crop remains complex due to the large number of interactive effects among environmental factors and the regulatory mechanisms that underlie these effects. Consequently, there is a substantial discrepancy between the number of studies conducted with a single or two factors simultaneously, and those with a more holistic approach. This review focuses on how climate change factors will coexist across the viticultural areas of the globe and summarises the main interactive mechanisms affecting crop performance. We highlight how the rise in temperatures will be enhanced when dealing with specific periods, such as the ripening months. Changes in crop phenology in response to temperature have been a major focus of most studies. However, how these physiological shifts may result in deleterious effects on yield and quality deserves further research. Rising temperatures will most certainly continue to represent the most imminent threat to viticulture due to its effects on grape phenology, composition and crop water requirements. Nevertheless, elevated CO2 may offer some relief through increased water use efficiency, as recent studies have shown. Within the repertoire of regulatory mechanisms that plants possess, hormones play a major role explaining the effects of combined stresses due to their crosstalk. In fact, growth regulators fine tune stress responses depending on the multiple stresses present. The paper focuses on the multistress responses mediated by ABA and jasmonate, and on the intricate interconnections of signalling among the different plant hormones.

Indirect effects of warming via phenology on reproductive success of alpine plants

Abstract Climate warming has induced pronounced shifts in the phenology of alpine plants worldwide, yet the impact of these changes on plant reproduction remains unclear, although phenology plays a vital role in reproduction. Based on a 7‐year field warming and altered precipitation experiment initiated in 2017, we measured three reproductive phenological events and seven reproductive traits of six dominant species, belonging to two flowering functional groups, to assess the effects of climate change on reproductive phenology and the reproductive consequence of changing the phenology in an alpine meadow on the eastern Tibetan Plateau from 2021 to 2023. Warming significantly advanced the start of flowering in early‐spring flowering (ESF) and mid‐summer flowering (MSF) plants, while the fruiting period of ESF plants remained stable. Furthermore, warming led to a decrease in the number of seeds and productivity of alpine plants, while seed size remained stable. Phenological changes regulate the reproductive success of alpine plants. Specifically, the start of flowering for ESF plants and the start of fruiting for MSF plants regulated the number of seeds and productivity of the two flowering functional groups, respectively. The increase in phenological niche overlap and intensification of interspecific competition, caused by different phenological responses of the flowering functional groups to warming, also are key factors contributing to the decline in seed production of alpine plants. Synthesis. These results demonstrate that the reproductive success of alpine plants would be decreased by earlier reproduction under climate warming, and alpine plants tend to maintain stable seed size in response to climate change. Our study emphasizes the important regulatory and indicative role of reproductive phenology in the sexual reproduction of alpine plants under future climate change.

Phenophases of Species of the Salix Genus in the Conditions of Osh City

The study of the phenology of urban trees and shrubs has increased dramatically worldwide in recent years, as changes in plant phenology may indicate the impacts of climate change at different scales. The aim of the study is to determine the patterns of the seasonal rhythm of individual species belonging to the Salixgenus in Osh. The studies were conducted in the period 2019-2023 at the Department of Biology, Chemistry and Nature Management of Osh State Pedagogical University. The subject of the study is 4 species of the genus Salix: Salix babylonica L., Salix turanica Nasarow, Salix wilhelmsiana M. Bieb. and Salix tenuijulis Ledeb. Phenological observations were carried out for 5 years using generally accepted phenological methods. The results of phenological observations in 2019-2023 show that the duration of the growing season in urban conditions is 240-245 days, and this indicator varies depending on climatic conditions. The observed species have differences in the flowering sequence, the beginning and duration of flowering. The total duration of flowering in the studied species is 25-35 days. The seasonal type of growth and phenological development of plants of the genus Salix is characterized by an early onset and late end of vegetation, stability of average phenological terms. Such a phenological rhythm of the studied species of the genus Salix makes it possible to consider cultivation for decorative and environmental purposes in urban conditions promising.

Phenological mismatch is less important than total nectar availability for checkerspot butterflies.

Changes in phenology are a conspicuous fingerprint of climate change, leading to fears that phenological mismatches among interacting species will be a leading cause of population declines and extinction. We used quantile regression to analyze museum collection data and estimate changes in the phenological overlap of Baltimore checkerspot butterflies and 12 common nectar plant species over several decades in two geographic regions. We combined these museum data with field estimates of each species' flower density and nectar sugar production to estimate changes in resource availability caused by shifts in phenological overlap. Phenological overlap (measured as the proportion of plant flowering during the flight period of an average butterfly) decreased through time, primarily because the flowering period of nectar plants was longer, but the flight period of butterflies was shorter in recent years. Our study was also motivated by the hypothesis that phenological mismatches may be more severe in the southern region due to a midsummer dearth in floral resources, but this hypothesis was not supported by our data. Although phenological overlap was somewhat smaller in the southern region, changes in overlap through time were similar in both regions. When phenological overlap was weighted by nectar sugar production of different species, the overlap increased in the southern region but decreased in the northern region (the opposite of our prediction). Overall, nectar resources were much more abundant at study sites in our northern region than in our southern region, possibly due to differences in land management. Our study demonstrates the complexities of phenological mismatch of interacting species and highlights that phenological changes may have small impacts on population viability.

Limitation of summer extreme high temperatures on radial growth relieve with increasing latitude in subtropics

Global warming has induced an increase in the intensity and frequency of summer extreme high temperature events in Chinese subtropical forest, which contributes to a large component of net primary ecological production among global forests. However, how summer extreme high temperature events would influence tree radial growth in these humid subtropical forest remains unclear. We investigated the non-linear response of tree radial growth to temperature, soil moisture and their mixed effect across broad latitude gradients in Chinese subtropical forests, using a method of modelling cambial growth kinetics of Schima superba. The results showed that radial growth was constrained by summer extreme high temperatures and this limiting effect relieved from south to north. However, we also found a growth constraint imposed by soil moisture during spring and autumn, which intensified toward northern sites. Coincidentally, the radial growth pattern showed a distinct transition from bimodal to unimodal from South to North sites, with no significant changes in cambium phenology over the time scale from 1986 to 2014 being observed. In general, we determined that limitation of extreme high temperatures on radial growth relieve with increasing latitude in subtropics. This study provides a theoretical basis for promoting the accurate assessment of carbon sink potential and for predicting future forest dynamics in subtropics.

Linking Vegetation Phenology to Net Ecosystem Productivity: Climate Change Impacts in the Northern Hemisphere Using Satellite Data

With global climate change, linking vegetation phenology with net ecosystem productivity (NEP) is crucial for assessing vegetation carbon storage capacity and predicting terrestrial ecosystem changes. However, there have been few studies investigating the relationship between vegetation phenology and NEP in the middle and high latitudes of the Northern Hemisphere. This study comprehensively analyzed vegetation phenological changes and their climate drivers using satellite data. It also investigated the spatial distribution and climate drivers of NEP and further analyzed the sensitivity of NEP to vegetation phenology. The results indicated that the average land surface phenology (LSP) was dominated by a monotonic trend in the study area. LSP derived from different satellite products and retrieval methods exhibited relatively consistent responses to climate. The average SOS and POS for different retrieval methods showed a higher negative correlation with nighttime temperatures compared to daytime temperatures. The average EOS exhibited a higher negative correlation with daytime temperatures than a positive correlation. The correlations between VPD and the average SOS, POS, and EOS showed that the proportion of negative correlations was higher than that of positive correlations. The average annual NEP ranged from 0 to 1000 gC·m−2. The cumulative trends of NEP were mainly monotonically increasing, accounting for 61.04%, followed by monotonically decreasing trends, which accounted for 17.95%. In high-latitude regions, the proportion of positive correlation between VPD and NEP was predominant, while the proportion of negative correlation was predominant in middle-latitude regions. The positive and negative correlations between soil moisture and NEP (48.08% vs. 51.92%) were basically consistent in the study area. The correlation between SOS and POS with NEP was predominantly negative. The correlation between EOS and NEP was overall characterized by a greater proportion of negative correlations than positive correlations. The correlation between LOS and NEP exhibited a positive relationship in most areas. The sensitivity of NEP to vegetation phenological parameters (SOS, POS, and EOS) was negative, while the sensitivity of NEP to LOS was positive (0.75 gC·m−2/d for EVI vs. 0.63 gC·m−2/d for LAI vs. 0.30 gC·m−2/d for SIF). This study provides new insights and a theoretical basis for exploring the relationship between vegetation phenology and NEP under global climate change.

Shifts in Plant Phenology Significantly Affect the Carbon Allocation in Different Plant Organs.

Earlier start of the growing season (SGS) and delayed end of the growing season (EGS) affect plant carbon uptake. However, the effects of phenological changes on carbon allocation to different plant organs remain unclear. Here, we examined the effects and potential mechanisms of phenological changes on carbon allocation to different organs over the northern hemisphere (> 30° N). We found the earlier SGS facilitated allocating carbon to roots in warm areas, and delayed EGS benefited allocating carbon to roots in dry areas. Moreover, the effects of SGS and EGS on carbon accumulation in different organs significantly enhanced over time. Path analyses indicated that phenological changes contributed to root-stem ratio mainly by regulating the growing season length. Our findings further highlight that phenological changes alter plants' investment strategies in carbon allocation for above- and below-ground parts, and considering this role is critical for accurately estimating the carbon budget in terrestrial ecosystems.

Climate‐associated variation in the within‐season dynamics of juvenile ticks in California

AbstractChanging climate has driven shifts in species phenology, influencing a range of ecological interactions from plant–pollinator to consumer–resource. Phenological changes in host–parasite systems have implications for pathogen transmission dynamics. The seasonal timing, or phenology, of peak larval and nymphal tick abundance is an important driver of tick‐borne pathogen prevalence through its effect on cohort‐to‐cohort transmission. Tick phenology is tightly linked to climatic factors such as temperature and humidity. Thus, variation in climate within and across regions could lead to differences in phenological patterns. These differences may explain regional variation in tick‐borne pathogen prevalence of the Lyme disease‐causing Borrelia bacteria in vector populations in the United States. For example, one factor thought to contribute to high Lyme disease prevalence in ticks in the eastern United States is the asynchronous phenology of ticks there, where potentially infected nymphal ticks emerge earlier in the season than uninfected larval ticks. This allows the infected nymphal ticks to transmit the pathogen to hosts that are subsequently fed upon by the next generation of larval ticks. In contrast, in the western United States where Lyme disease prevalence is generally much lower, tick phenology is thought to be more synchronous with uninfected larvae emerging slightly before, or at the same time as, potentially infected nymphs, reducing horizontal transmission potential. Sampling larval and nymphal ticks, and their host‐feeding phenology, both across large spatial gradients and through time, is challenging, which hampers attempts to conduct detailed studies of phenology to link it with pathogen prevalence. In this study, we demonstrate through intensive within‐season sampling that the relative abundance and seasonality of larval and nymphal ticks are highly variable along a latitudinal gradient and likely reflect the variable climate in the far western United States with potential consequences for pathogen transmission. We find that feeding patterns were variable and synchronous feeding of juvenile ticks on key blood meal hosts was associated with mean temperature. By characterizing within‐season phenological patterns of the Lyme disease vector throughout a climatically heterogeneous region, we can begin to identify areas with high potential for tick‐borne disease risk and underlying mechanisms at a finer scale.

Greening‐Induced Biophysical Impacts Lead to Earlier Spring and Autumn Phenology in Temperate and Boreal Forests

AbstractTree phenology, the timing of periodic biological events in trees, is highly sensitive to climate change. Previous studies have indicated that forest greening can impact the local climate by modifying the seasonal surface energy budget. However, the understanding of tree phenological responses to forest greening at large spatial scales remains limited. Utilizing satellite‐derived phenological and leaf area index data spanning from 2001 to 2021, herein we show that forest greening led to earlier spring and autumn phenology in both temperate and boreal forests. Our findings demonstrated that forest greening during winter and spring contributed to a reduction in surface albedo, resulting in biophysical warming and consequently advancing spring leaf phenology. Conversely, forest greening in summer and autumn induced biophysical cooling through increased evapotranspiration, leading to an earlier onset of autumn leaf phenology. Our findings highlight the significant impact of forest greening‐induced local seasonal climate changes on shaping tree phenology in temperate and boreal forests. It is crucial to consider these greening‐induced alterations in microclimate conditions when modeling changes in tree phenology under future climate warming scenarios.

Variations of Lake Ice Phenology Derived from MODIS LST Products and the Influencing Factors in Northeast China

Lake ice phenology serves as a sensitive indicator of climate change in the lake-rich Northeast China. In this study, the freeze-up date (FUD), break-up date (BUD), and ice cover duration (ICD) of 31 lakes were extracted from a time series of the land water surface temperature (LWST) derived from the combined MOD11A1 and MYD11A1 products for the hydrological years 2001 to 2021. Our analysis showed a high correlation between the ice phenology measures derived by our study and those provided by hydrological records (R2 of 0.89) and public datasets (R2 > 0.7). There was a notable coherence in lake ice phenology in Northeast China, with a trend in later freeze-up (0.21 days/year) and earlier break-up (0.19 days/year) dates, resulting in shorter ice cover duration (0.50 days/year). The lake ice phenology of freshwater lakes exhibited a faster rate of change compared to saltwater lakes during the period from HY2001 to HY2020. We used redundancy analysis and correlation analysis to study the relationships between the LWST and lake ice phenology with various influencing factors, including lake properties, local climate factors, and atmospheric circulation. Solar radiation, latitude, and air temperature were found to be the primary factors. The FUD was more closely related to lake characteristics, while the BUD was linked to local climate factors. The large-scale oscillations were found to influence the changes in lake ice phenology via the coupled influence of air temperature and precipitation. The Antarctic Oscillation and North Atlantic Oscillation correlate more with LWST in winter, and the Arctic Oscillation correlates more with the ICD.

Changes of nestling ringing dates in nine bird species over seven decades

Climate change co-occurs with an advancement of avian breeding season (indexed as laying dates or fledging dates) in the temperate zone, suggesting a causality between them. Here, we investigate whether the long-term shifts in nestling (chick) ringing dates also mirror this phenomenon. This index is biased by inherent shortcomings, such as the non-independence of dates (in nestmates, colony members), poor accuracy (long period suitable for ringing), and strange shape of distributions. These shortcomings can be reduced by applying the median of annual ringing dates as an index of breeding phenology. The advantage of this index is that data are available for long periods and large sample sizes. By accepting certain compromise between statistical discipline and fieldwork realities, we examined changes in the breeding phenology of 9 bird species from 1951 to 2020 in Hungary. We found that the annual median of ringing dates advanced significantly (by 9–14 days) in the Black-headed Gull, Common Kestrel, Barn Swallow, Great Tit, and Eurasian Blue Tit. Contrarily, no significant (all P > 0.16) changes occurred in the case of the Common Tern, Black-crowned Night-heron, Common Buzzard, and Long-eared Owl. We also found that the proportion of Great Tits’ second brood has been reduced in recent decades.

Characteristics and Correlation Study of Mountainous Lake Ice Phenology Changes in Xinjiang, China Based on Passive Microwave Remote Sensing Data

Lake ice phenology directly reflects local climate changes, serving as a key indicator of climate change. In today’s rapidly evolving climate, utilizing advanced remote sensing techniques to quickly extract long-term lake ice phenology features and studying their correlation with other climate factors is crucial. This study focuses on lakes in Xinjiang, China, with a mountainous area greater than 100 km2, including Sayram Lake, Ayahkum Lake, Achihkul Lake, Jingyu Lake, and Ahsaykan Lake. The Bayesian ensemble change detection algorithm was employed to extract lake ice phenology information, and the Mann–Kendall (MK) non-parametric test was used to analyze trends. The visual interpretation method was used to interpret the spatial evolution characteristics of lake ice, and the Pearson correlation coefficient was used to explore the driving factors of lake ice phenology. Results indicate the following: (1) Jingyu Lake exhibited the most significant delay in both freezing and complete freezing days, while Ayahkum Lake showed the most stable pattern. Ahsaykan Lake demonstrated the least delay in both starting and complete melting days. (2) Sayram Lake’s ice evolution was unstable, with wind causing variability in the locations where freezing begins and melting spreading from the west shore. Ayahkum Lake, Ahsaykan Lake, and Jingyu Lake exhibited similar seasonal variations, while Achihkul Lake’s ice spatial changes spread from the east to the center during freezing and from the center to the shore during melting. (3) The study found that the freeze–thaw process is influenced by a combination of factors including lake area, precipitation, wind speed, and temperature.

Chilling and Forcing Requirements of Wintersweet (Chimonanthus praecox L.) Flowering in China

Numerous studies have reported phenological changes and their driving mechanisms in spring flowering plants. However, there is little research on the shifts of winter flowering phenology and its response to forcing and chilling requirements. Based on the China Phenological Observation Network (CPON) ground observation data from nine sites over the past 20 years, we explored the spatial and temporal variation patterns of flowering plants and their response to chilling and forcing in wintersweet (Chimonanthus praecox L.), a common winter flowering plant species in temperate and subtropical zones of China. We used three chilling models (chilling hour, Utah, and dynamic models) and the growing degree hours (GDHs) model to calculate each site’s daily chilling and forcing. Using the partial least squares (PLSs) regression approach, we established the relationship between the first flowering date (FFD) and pre-season chilling and forcing in wintersweet, based on which we identified chilling and forcing periods and calculated chilling and forcing requirements. This study found that the FFD of wintersweet in China showed an overall advancement trend during the last 20 years. Still, there were temporal and spatial differences in the FFD of wintersweet among different sites. The PLS results showed that wintersweet also had periods of chilling and forcing, both of which co-regulated wintersweet flowering. We found the forcing and chilling requirements of wintersweet varied significantly from site to site. The higher the latitude is, the more chilling requirements are needed. The chilling requirements for wintersweet were about 6.9–34.9 Chill Portions (CPs) and 1.4–21.6 CP in the temperate and subtropical zones, respectively, with corresponding forcing requirements of 3.2–1922.9 GDH and 965.3–8482.6 GDH, respectively. In addition, we found that the temperature requirements of wintersweet were correlated by a negative exponential relationship, suggesting that chilling and forcing requirements have an antagonistic effect on initiating flowering phenology. Our results could help us understand how flowering dates of winter flowering plants respond to climate change.

Investigating climatic drivers of snow phenology by considering key-substage heterogeneity

Investigating the main climatic drivers responsible for changes in snow cover phenology (SCP) is crucial for making scientific countermeasures to ensure water resources security in global mountainous regions. However, most studies have explored drivers of SCP changes using a fixed substage division scheme and correlation analysis (referred to as the traditional method), potentially limiting reliability and accuracy in mountainous areas with complex terrain and climate. Here, a novel method is developed to efficiently identify main climatic drivers of SCP changes. This method employs a flexible scheme to account for the spatial heterogeneity of the dominant sub-period (the sub-period with the major climatic effect) in combination with regression analysis. Using the arid region of China as a case study, the new method was applied to three SCP parameters including snow cover days, snow start date, and snow end date, based on a seamless snow cover dataset from 2002 to 2019. The method’s effectiveness was evaluated by comparing it with the traditional method. The results indicate significant spatial heterogeneity in the dominant sub-period(s), closely associated with local temperature and elevation. The traditional method failed to accurately identify the main drivers of SCP changes, as evidenced by sub-region and elevation zone analyses showing adjusted coefficient of determination (R2) of < 0.5 in most cases. This inadequacy is attributed to its fixed and inappropriate scheme of substage division. In contrast, the new method, with its flexible scheme, achieved much higher adjusted R2 values (mostly > 0.5) and exhibited better performances in predicting SCP changes. Thanks to the new method, climatic causes of SCP changes were successfully identified in 12 hotspots (regions with significant SCP changes), all with adjusted R2 > 0.5. The climatic causes were found to vary significantly across different hotspot regions and SCP parameters. The proposed method holds significant potential to enhance the reliability of analyses concerning main climatic drivers of SCP changes in mountainous regions globally.

Strength of seasonality and type of migratory cue determine the fitness consequences of changing phenology for migratory animals

Phenological mismatch has been highlighted as a reason why climate change is causing declines of migratory populations. The likelihood of declines due to phenological mismatch might depend on what cues trigger migration. Migrants that use environmental cues (e.g. temperature, resource availability) to trigger migration are often considered to be less vulnerable than migrants that use temporal information (e.g. photoperiod). We developed a proof‐of‐concept model that demonstrates that which cue type performs better in the context of phenological change can depend on differences in seasonal amplitude between the habitats used by a migrant. Environmental cues perform better than temporal cues when the habitat that undergoes a phenological change has a larger seasonal amplitude. This result aligns with observations that populations of short‐distance migrants that use environmental cues are less likely to decline as a consequence of phenological mismatch than long‐distance avian migrants that use temporal cues. Temporal cues perform better than environmental cues when the habitat that undergoes a phenological change has a smaller seasonal amplitude. This result may correspond to empirical scenarios where the more seasonal habitat is associated with variation in precipitation patterns or human actions that are not changing in phenology. In addition to these results, we offer distinctions that will help clarify future work on phenological mismatch. First, we highlight the difference between the cue accuracy (difference between the timing of migration using the cue and optimal migration timing) and the cue efficacy (the difference between the fitness using the cue and the fitness using optimal migration). Second, we recommend considering both how the benefits available from migrating and the benefits that are captured by migrants change with phenological change.

The temporal distribution of endophytic and exophytic insect guilds responds to host plant phenology in the Brazilian Savannah

Abstract Niche theory predicts high specialisation in species‐rich environments such as neotropics, where plant‐herbivore interactions are ubiquitous in all terrestrial systems. However, there is much to be explored on how different insect guilds respond to plant phenology in these specialised environments. Using a Fabaceae‐herbivore community as an ecological model, we evaluated how plant phenology affects the abundance and shapes the temporal distribution of exophytic (folivore chewers) and endophytic (seed chewers) insects. We tested the specialisation hypothesis, predicting insect species on only one or a few host plants, with a seasonal pattern of occurrence, many rare and few abundant species. Additionally, we analysed the relationship between plant phenology and environmental factors (temperature and precipitation). We conducted fieldwork with five species and 97 individuals of Fabaceae in Brazilian Savannah and performed an insect‐rearing study in the laboratory. We found an immediately synchronised relationship between endophytic insects and plant phenology in the dry season, whereas exophytic were throughout the year. Only six species from the exophytic guild, out of a total of 87 species for both guilds, fed on more than one host plant, showing a specialised network. Endophytic herbivores are more abundant, ephemeral and predictable than exophytic ones. We also found a negative relationship between fruiting and precipitation and a positive relationship between new leaves and temperature and precipitation. Our study shows that the temporal distribution of insect‐herbivore guilds responds to plant phenology. In a scenario of global warming with effects on the annual precipitation, endophytic insects are most vulnerable to local extinction due to temporal changes in plant phenology than the exophytic ones.