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Seasons and Life Cycles

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Abstract

An apparent contradiction has arisen in studies of plant phenological response to climatic warming: Field and satellite data at the community and biome levels indicate a lengthening of the growing season across much of the Northern Hemisphere ( 1 – 6 ) and—where data exist—in the Southern Hemisphere ( 5 , 7 , 8 ), yet life history observations of individual species suggest that many species often shorten their life cycle in response to warming ( 9 – 12 ). Here, we pair evolutionary and ecological viewpoints to resolve this conundrum.

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... Long-term in situ or remote sensing observations and manipulative warming experiments are the main methods used in phenological studies at present (Arft et al., 1999;Walker et al., 2006;Cleland et al., 2007;Morisette et al., 2009;Pieper et al., 2011;Li et al., 2016). Some studies have found that phenological temperature sensitivities are mismatched at community and species levels (Steltzer and Post, 2009;Meng et al., 2016;Meng et al., 2017). This mismatch may be caused by divergent responses of different species to warming (Steltzer and Post, 2009;. ...
... Some studies have found that phenological temperature sensitivities are mismatched at community and species levels (Steltzer and Post, 2009;Meng et al., 2016;Meng et al., 2017). This mismatch may be caused by divergent responses of different species to warming (Steltzer and Post, 2009;. However, these studies only consider that warming is the principal factor, ignoring daily or annual frequent temperature fluctuations (Menzel et al., 2011;Kosaka and Xie, 2013). ...
... Many studies have shown that phenological temperature sensitivity is species-specific, even under similar environmental conditions (Diez et al., 2012;Iler et al., 2013;Wang et al., 2014a, Wang et al., 2014b. Hence, phenological changes at the species level are difficult to match with changes at the community level due to divergent responses by different species (Steltzer and Post, 2009). However, few studies have focused on the compensatory effects of different species to community phenological sequences based on field observations. ...
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Few studies have focused on the response of plant community phenology to temperature change using manipulative experiments. A lack of understanding of whether responses of community reproductive and vegetative phenological sequences to warming and cooling are asymmetrical or symmetrical limits our capacity to predict responses under warming and cooling. A reciprocal transplant experiment was conducted for 3 years to evaluate response patterns of the temperature sensitivities of community phenological sequences to warming (transferred downward) and cooling (transferred upward) along four elevations on the Tibetan Plateau. We found that the temperature sensitivities of flowering stages had asymmetric responses to warming and cooling, whereas symmetric responses to warming and cooling were observed for the vegetative phenological sequences. Our findings showed that coverage changes of flowering functional groups (FFGs; i.e., early-spring FFG, midsummer FFG, and late-autumn FFG) and their compensation effects combined with required accumulated soil temperatureto codetermined the asymmetric and symmetric responses of community phenological sequences to warming and cooling. These results suggest that coverage change in FFGs on warming and cooling processes can be a primary driver of community phenological variation and may lead to inaccurate phenlogical estimation at large scale, such as based on remote sensing.
... Phenologythe timing of key events in an organism's development or life history [1] strongly affects individual fitness; interactions among individuals, populations, and species; the generation and maintenance of species boundaries; and how populations and species are managed [2,3]. Perhaps because of its origins in northern Europe [4,5], the study of phenology has for more than 150 years emphasized annually recurring seasonal or cyclic life-history phenomena [6]. Common objects of phenological investigation include the onset of flowering of individual plant species, the return to temperate (northern or southern) nesting grounds of seasonally migratory birds, and peak colors of foliage as the leaves of temperate deciduous trees senesce. ...
... Common objects of phenological investigation include the onset of flowering of individual plant species, the return to temperate (northern or southern) nesting grounds of seasonally migratory birds, and peak colors of foliage as the leaves of temperate deciduous trees senesce. The primary environmental drivers of phenology in the temperate zone are the predictably large, seasonal changes in daylength, precipitation, and especially the shift from below-to above-freezing temperatures [1,6]. We refer to the emphasis on large seasonal phenological drivers that occur predictably on annual cycles as the 'temperate phenological paradigm'. ...
Article
Earth's most speciose biomes are in the tropics, yet tropical plant phenology remains poorly understood. Tropical phenological data are comparatively scarce and viewed through the lens of a 'temperate phenological paradigm' expecting phenological traits to respond to strong, predictably annual shifts in climate (e.g., between subfreezing and frost-free periods). Digitized herbarium data greatly expand existing phenological data for tropical plants; and circular data, statistics, and models are more appropriate for analyzing tropical (and temperate) phenological datasets. Phylogenetic information, which remains seldom applied in phenological investigations, provides new insights into phenological responses of large groups of related species to climate. Consistent combined use of herbarium data, circular statistical distributions, and robust phylogenies will rapidly advance our understanding of tropical - and temperate - phenology.
... The challenge of this method is that long-term field observations are mainly focused on the phenology of a few species (Fu et al. 2014;Shen et al. 2015). Due to the diverse responses of different species to warming, species-level field data often poorly match satellite observations for the entire community (Steltzer and Post 2009). Thus, there is an urgent need for long-term community-level field data to assess how well satellite data match field data in terms of vegetation growth at temporal scales with, for example, notable climate change. ...
... However, we cannot rule out other nonmutually exclusive reasons for the earlier SOPG. For instance, the advancement in SOG could impose cascading effects on SOPG due to the intrinsic factors controlling the duration of annual plant growth (Steltzer & Post 2009). The loss of certain species that bridge the phenological gap in the middle of the growing season may also cause the earlier SOPG occurrence (Oehri et al. 2017). ...
Article
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Satellite‐derived normalized difference vegetation index (NDVI) data are increasingly relied on to reveal the growth responses of vegetation to climate change, yet the vegetation growth tracking accuracy of these data remains unclear due to a lack of long‐term field data. Here, we adopted a unique field‐measured seasonal aboveground biomass dataset from 1982–2014 to assess the potential of employing satellite‐derived NDVI data to match field data in regard to the interannual variability in seasonal vegetation growth in a Tibetan alpine grassland. We revealed that GIMMS NDVI data captured the advancement of field‐measured vegetation growth throughout the entire study period but not from 2000–2014, while MODIS NDVI data still observed this advancing trend after 2000 to a limited extent. However, satellite‐derived NDVI data consistently underestimated the advancement degree of field‐measured vegetation growth, regardless of whether GIMMS or MODIS NDVI data were considered. We tentatively attribute this underestimation to an increased ratio of grass biomass to forb biomass, which could delay the advancement of NDVI development but not affect that of field‐measured biomass development. Our results suggest that satellite‐derived NDVI data may miss critical responses of vegetation growth to global climate change, potentially due to long‐term shifts in plant community composition.
... The lack of resolution in late season phenological responses is due to several factors including conflicting evidence on patterns and drivers of senescence [33][34][35] , and fewer studies overall for autumnal phenophases 8 . Asynchronous shifts in early and late season phenophases may result in the lengthening or contracting of the growing, flowering, and/or fruiting seasons 21,24,[36][37][38][39] , with important implications for primary production and trophic interactions 40,41 . On the other hand, the start and end of plant phenoperiods (growth, flowering, and fruiting periods) may shift in concert because of fixed periodicity in phenophase duration 9,39,42 (Fig. 1, unison response scenario). ...
... It is important to note, however, that the shifts we observed were at the average species level, which can differ from the community and ecosystem-level responses, as only a subset of species in the community were sampled at each site. Variation in species' responses to warming can enhance the likelihood of observing an increase in growing season length at the community or ecosystem level and does not necessarily mean that species' annual life cycles are being extended 38 . ...
Article
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Rapid climate warming is altering Arctic and alpine tundra ecosystem structure and function, including shifts in plant phenology. While the advancement of green up and flowering are well-documented, it remains unclear whether all phenophases, particularly those later in the season, will shift in unison or respond divergently to warming. Here, we present the largest synthesis to our knowledge of experimental warming effects on tundra plant phenology from the International Tundra Experiment. We examine the effect of warming on a suite of season-wide plant phenophases. Results challenge the expectation that all phenophases will advance in unison to warming. Instead, we find that experimental warming caused: (1) larger phenological shifts in reproductive versus vegetative phenophases and (2) advanced reproductive phenophases and green up but delayed leaf senescence which translated to a lengthening of the growing season by approximately 3%. Patterns were consistent across sites, plant species and over time. The advancement of reproductive seasons and lengthening of growing seasons may have significant consequences for trophic interactions and ecosystem function across the tundra. It is unclear whether climate driven phenological shifts of tundra plants are consistent across the plant growing season. Here the authors analyse data from a network of field warming experiments in Arctic and alpine tundra, finding that warming differentially affects the timing and duration of reproductive and vegetative phenology.
... Numerous plant and animal species already responded with a significant advance in the timing of seasonal activities (i.e. their phenology) (Walther et al. 2002, Parmesan 2006, Peñuelas et al. 2009, Steltzer and Post 2009. These phenological trends have been repeatedly linked to recent climatic changes (Menzel et al. 2006, Scranton and Amarasekare 2017), and include, for instance, earlier flowering and leafing in spring and, to a lesser extent, a delay in the onset of autumnal phenological events such as leaf colouring and leaf fall (Wolkovich et al. 2012). ...
... These phenological trends have been repeatedly linked to recent climatic changes (Menzel et al. 2006, Scranton and Amarasekare 2017), and include, for instance, earlier flowering and leafing in spring and, to a lesser extent, a delay in the onset of autumnal phenological events such as leaf colouring and leaf fall (Wolkovich et al. 2012). Furthermore, both empirical ground and satellite data uncovered a progressive lengthening of the growing season across temperate and polar latitudes, as a response to warming air temperatures during the 20 th century (Menzel and Fabian 1999, Menzel et al. 2006, Rosenzweig et al. 2008, Peñuelas et al. 2009, Steltzer and Post 2009, Scranton and Amarasekare 2017. Since the early 1960s a significant advance and increase in the annual amplitude of the seasonal cycle of atmospheric CO2 has also been observed, likely reflecting changes in seasonal plant activity following climate change (Keeling et al. 1996). ...
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Linear landscape elements such as hedgerows and road verges can connect isolated fragments of natural and semi-natural habitats, thereby facilitating the movements of species across fragmented landscapes. This could be particularly important as the need for species to move is predicted to increase substantially with climate change. However, so far, we know little about the efficiency of these linear structures to act as habitats or movement corridors for plant species with limited dispersal capacity and specific habitat requirements. Moreover, we do not know whether linear landscape elements will continue to deliver this function under a changing climate. In this research, we show that hedgerows and road verges across Europe can support diverse plant communities, including also species that are usually associated with large and stable habitats such as oldgrowth forests and species-rich, semi-natural grasslands. Furthermore, these linear structures may also serve as a dispersal route for some, but certainly not all, plant species. Factors such as time and spatiotemporal connectivity played an important role here (i.e. ancient corridors with long-term connection to a source population in a larger habitat patch are generally more effective), but also other habitat-specific features including soil properties, microclimate and management. We conclude that hedgerows and road verges may contribute to species persistence and increase functional connectivity in fragmented agricultural landscapes. Further research is needed to elucidate how climate change will alter plant community dynamics in linear elements and influence their future efficiency as ecological corridors. Finally, we emphasize the importance to integrate efficient strategies for preservation, creation and management of linear landscape elements in policies and management plans, both at national (e.g. agri-environment schemes) and international level (e.g. European Common Agricultural Policy).
... However, the total amount of production may also be influenced by biological elements as of the duration of cropping growth, crop calendar, and cycle periods. The observed genetic changes over the 20th century in Northern Hemisphere identified the longer crop growth life cycle in response to crops to the global warming situation (Steltzer and Post, 2009). Moreover, the recent global warming from the 1980s, in global cultivation of maize and wheat, has responded negatively in growth and production, while other crop production (e.g., rice) response signals still been imprecise (Lobell et al., 2008). ...
... China is a first and rapidly industrial growing developing country and the highest emission of CO 2 gas and also the most risk and vulnerable countries due to CC (Turral et al., 2011). Although many kinds of research in China have focused on the effect of CC on food security [Steltzer andPost (2009), Lin et al. (2005), Piao et al. (2010)], however, some systematic researches which directly associated CC on food security still have to lack, particularly at the overall national scale. Generally, food security estimation regards not the only production of food but also several parameters including food consumption and added complexity as well as multiple socioeconomic and agro-economic data, different factors, and model simulations (Schmidhuber and Tubiello, 2007;Tubiello et al., 2007). ...
Article
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This review has mainly focused on China and Bangladesh, as taken in some parts of comparison due to climate changes (CC) affected the country. The study implicated a range of socioeconomic and agro-economic literature that was developed subsequent two different development trail linked with the Intergovernmental Panel on Climate Change (IPCC) pessimistic and optimistic scenarios. The food security index (FSI) has proven to be a powerful and reliable quantitative cause-effect analysis tool. Analysis of the literature results compared with other factors such as agricultural land area, population growth and GDP growth, showed that CC has only a modest positive impact on food security. Overall, socioeconomic development pathways have a major impact on future food security trends in China and Bangladesh. Furthermore, emphasis on environmental sustainability, the impartial expansion path associated with the pessimistic emissions scenario, has proven to be far better in ensuring food safety than the other optimistic path. In regression analyzed literature, it was found that yield growth rate was a much better indicator in food security analysis than crop yield per season. Therefore, the yield enhancements on a yearly basis are highly consequence in ensuring food security for the countries with a big sized and densely populated region like China and Bangladesh. The comparatively lower FSI, values recommended that per capita food consumption in China is on a stable growth while Bangladesh would face deficiencies. Therefore, there is a need to focus more on food safety and balanced nutrition, taking into account climatic conditions. The review information derived from the study is similarly suitable for formulating climate change and agricultural relevant planning and policies.
... В одних случаях изменения климатических условий могут влиять на продолжительность репродуктивных фаз бутонизации, цветения и плодоношения, как, например, было отмечено у однолетних и многолетних растений [2,16]. В других случаях жизненный цикл может сохранять свою структуру и продолжительность, но сдвигаться во времени [17,18]. В наших исследованиях мы затронули только продолжительность цветения видов, однако влияние климатических факторов на даты бутонизации, появления первого цветка, окончания цветения также интересно и перспективно для дальнейшего изучения. ...
Article
The phenological responses of plants to changing weather conditions are very strong and can serve as an indicator of global climate change. If we understand how individual species respond to changing conditions, we can represent how ecosystems will change. The aim of this study was to analyze the exposure of climatic factors (air temperature and precipitation) on the fl owering duration of the wild vascular plants species in the Karadag Nature Reserve (Crimea). In general, 152 species were taken into account with a number of phenological observations from 5 to 8 years. Correlation analysis between the fl owering duration and the climatic parameters revealed a signifi cant response in 89 (58.6%) species. Moreover, the climatic factors of the current vegetative season impacted 71 species fl owering, previous vegetative season impacted 4 species fl owering, and both vegetative seasons impacted 14 species fl owering. Air temperature and precipitation equally impacted the fl owering duration: air temperature impacted 35 (41.2%) species fl owering; precipitation impacted 32 (37.7%) species fl owering; both factors impacted 18 (21.1%) species flowering. The flowering duration mostly was negatively correlated with air temperature values and positively with precipitation amount. Mesophytes and the forest community species were the most sensitive to the climatic factors; euxerophytes and the steppe community species were the least sensitive to the climatic factors.
... Global warming has alleviated the previous climatic restrictions on vegetation growth and has promoted the advancement of vegetation spring phenology (Chuine et al., 2010;Shen et al., 2014a;Chmura et al., 2019;Ganjurjav et al., 2021), especially in boreal and temperate regions (Zhang et al., 2004;Steltzer and Post, 2009). ...
Article
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Recent studies have revealed that the influence of diurnal temperature on spring phenology is asymmetric, and the faster nighttime warming in the Northern Hemisphere (NH) has a complex impact on spring phenology. Our understanding from the sensitivity of the start of the growing season (SOS) to daytime (ST_daytime) and nighttime temperatures (ST_nighttime) has urgently needs to be improved. In this study, the SOS sensitivity to diurnal temperature in the middle and high latitudes of the NH (>30°N) from 1982‐2015 is estimated. The results indicate that although SOS showed stronger sensitivity to daytime than nighttime temperature in most parts of the study areas, the influence of daytime temperature on SOS is decreasing, while the influence of nighttime temperature on SOS is increasing. The variations in ST_daytime and ST_nighttime along the latitude gradient were significantly correlated with the warming rate of the preseason diurnal temperature (p<0.01). The SOS between 40°N and 70°N was more sensitive to daytime temperature, while ST_nighttime was higher than ST_daytime at other latitudes due to topography and rapid nighttime warming. On the altitude gradient, the SOS was more sensitive to daytime temperature in areas below 800 m and 2000‐4000 m. ST_nighttime exceeded ST_daytime at other altitudes owing to nighttime warming relief of the severe restrictions on phenological processes and the reduction in frost risk. To reach a comprehensive characterization of the interaction between vegetation and climate systems, the current study suggests more investigation on the response of SOS to diurnal temperature on large scales. This article is protected by copyright. All rights reserved.
... Major food crops are impacted due to rise or fall in temperature, changes in rainfall patterns, global warming due to increased GHGs emissions, and soil abiotic stress caused by different heavy metal (Shah et al., 2020a;Raza et al., 2022) ultimately shifting the biological setups like crop cycle, insects, pests and diseases invasion, and growth periods. During 20th century, a longer crop life cycle was noticed as the most widely observed biological fluctuation in response to global warming in Northern Hemisphere (Steltzer and Post, 2009;Livensperger et al., 2019). Wheat and rice are among the major food crops that have reacted negatively to global warming in the last three decades, though the yield responses have still been under consideration and satisfied grain yields have been observed in various regions (Raza et al., 2019). ...
Article
Full-text available
Climatic variability has been acquiring an extensive consideration due to its widespread ability to impact food production and livelihoods. Climate change has the potential to intersperse global approaches in alleviating hunger and undernutrition. It is hypothesized that climate shifts bring substantial negative impacts on food production systems, thereby intimidating food security. Vast developments have been made addressing the global climate change, undernourishment, and hunger for the last few decades, partly due to the increase in food productivity through augmented agricultural managements. However, the growing population has increased the demand for food, putting pressure on food systems. Moreover, the potential climate change impacts are still unclear more obviously at the regional scales. Climate change is expected to boost food insecurity challenges in areas already vulnerable to climate change. Human-induced climate change is expected to impact food quality, quantity, and potentiality to dispense it equitably. Global capabilities to ascertain the food security and nutritional reasonableness facing expeditious shifts in biophysical conditions are likely to be the main factors determining the level of global disease incidence. It can be apprehended that all food security components (mainly food access and utilization) likely be under indirect effect via pledged impacts on ménage, incomes, and damages to health. The corroboration supports the dire need for huge focused investments in mitigation and adaptation measures to have sustainable, climate-smart, eco-friendly, and climate stress resilient food production systems. In this paper, we discussed the foremost pathways of how climate change impacts our food production systems as well as the social, and economic factors that in the mastery of unbiased food distribution. Likewise, we analyze the research gaps and biases about climate change and food security. Climate change is often responsible for food insecurity issues, not focusing on the fact that food production systems have magnified the climate change process. Provided the critical threats to food security, the focus needs to be shifted to an implementation oriented-agenda to potentially cope with current challenges. Therefore, this review seeks to have a more unprejudiced view and thus interpret the fusion association between climate change and food security by imperatively scrutinizing all factors.
... In the mid-latitudes of the Northern Hemisphere, air temperature has a significantly negative effect on the start of the growing season (SOS) and end of the growing season (EOS), whereas rainfall has a significantly negative effect on SOS and a positive effect on EOS (Steltzer and Post, 2009;Ren et al., 2020). Increasing precipitation advances SOS in the freshwater marshes of northeast China, but delays SOS in arid Central Asia (Shen et al., 2019;Wu et al., 2021;Li et al., 2021c). ...
Article
Hydrological regimes can combine with climatic factors to affect plant phenology; however, few studies have attempted to quantify their complex influences on plant phenology in floodplain wetlands. We obtained phenological information on Carex vegetation through MODIS normalized difference vegetation index (NDVI) data during 2001-2020, and monthly field investigation during 2011-2020. We then explored how these data were correlated with climatic factors and flood regimes in a Yangtze River-connected floodplain wetland (Dongting Lake, China). Our results showed that warmer temperature tended to advance the start of the pre-flooding growing season (SOS1), with a relative contribution of 76.1 %. Flood rising time strongly contributed to controlling the end of the pre-flooding growing season. Flood recession time and inundation duration were dominant factors determining the start of the post-flooding growing season (SOS2). Earlier flood recession time and shortened inundation duration tended to advance the SOS2. Shortened inundation duration, earlier flood recession time, and lower solar radiation tended to advance the end of the post-flooding growing season. The phenology of Carex distributed at high-elevation areas was more affected by hydrology than that of Carex distributed at low-elevation areas. Thus, climatic factors strongly affect the phenology of Carex during the pre-flooding growing season, whereas flood regimes play a dominant role in determining the phenology in the post-flooding growing season. The different responses of Carex phenology to climatic and flooding factors may provide insights for the conservation and management of floodplain wetlands in Yangtze River because Carex are primary food source and habitat for herbivorous waterfowls.
... Major food crops are impacted due to rise or fall in temperature, changes in rainfall patterns, global warming due to increased GHGs emissions, and soil abiotic stress caused by different heavy metal (Shah et al., 2020a;Raza et al., 2022) ultimately shifting the biological setups like crop cycle, insects, pests and diseases invasion, and growth periods. During 20th century, a longer crop life cycle was noticed as the most widely observed biological fluctuation in response to global warming in Northern Hemisphere (Steltzer and Post, 2009;Livensperger et al., 2019). Wheat and rice are among the major food crops that have reacted negatively to global warming in the last three decades, though the yield responses have still been under consideration and satisfied grain yields have been observed in various regions (Raza et al., 2019). ...
Article
Full-text available
Climatic variability has been acquiring an extensive consideration due to its widespread ability to impact food production and livelihoods. Climate change has the potential to intersperse global approaches in alleviating hunger and undernutrition. It is hypothesized that climate shifts bring substantial negative impacts on food production systems, thereby intimidating food security. Vast developments have been made addressing the global climate change, undernourishment, and hunger for the last few decades, partly due to the increase in food productivity through augmented agricultural managements. However, the growing population has increased the demand for food, putting pressure on food systems. Moreover, the potential climate change impacts are still unclear more obviously at the regional scales. Climate change is expected to boost food insecurity challenges in areas already vulnerable to climate change. Human-induced climate change is expected to impact food quality, quantity, and potentiality to dispense it equitably. Global capabilities to ascertain the food security and nutritional reasonableness facing expeditious shifts in biophysical conditions are likely to be the main factors determining the level of global disease incidence. It can be apprehended that all food security components (mainly food access and utilization) likely be under indirect effect via pledged impacts on ménage, incomes, and damages to health. The corroboration supports the dire need for huge focused investments in mitigation and adaptation measures to have sustainable, climate-smart, eco-friendly, and climate stress resilient food production systems. In this paper, we discussed the foremost pathways of how climate change impacts our food production systems as well as the social, and economic factors that in the mastery of unbiased food distribution. Likewise, we analyze the research gaps and biases about climate change and food security. Climate change is often responsible for food insecurity issues, not focusing on the fact that food production systems have magnified the climate change process. Provided the critical threats to food security, the focus needs to be shifted to an implementation oriented- agenda to potentially cope with current challenges. Therefore, this review seeks to have a more unprejudiced view and thus interpret the fusion association between climate change and food security by imperatively scrutinizing all factors.
... Third, and more importantly, warming could both advance or delay the phenology of different species in a community due to different adaptive evolutionary traits, which could resulted no change in community phenology, and previous studies have indicated that the responses of individual plant phenology to warming could not predict the responses of the community to warming. (Meng et al. 2017;Steltzer and Post 2009). Inconsistent with a previous report (Meng et al. 2017), there were no changes in the relative coverage of ESF or MSF under either warming rate (Fig. S3). ...
Article
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There is a debate about unmatched results between manipulative warming using constant warming rates every year (CW) and long-term observations warming affect temperature sensitive of flowering phenology, and it is probable because that long-term observations could represent the actual yearly increase in temperature (i.e., a yearly stepwise warming rate per year, SW) which would differ from CW and their effects would be regulated by precipitation alteration. Here we conducted a warming experiment with CW (temperature increase by +1 ºC and sustained this elevated temperature for the duration of the study) and SW (temperature increase by + 0.25 ºC progressively each year) with precipitation addition in an alpine grassland for four years. Our results showed that neither warming rates affected community flowering phenology. However, precipitation addition advanced onsets of flowering for early-spring flowering (ESF) and mid-summer flowering (MSF) groups, and advanced the end date of flowering for ESF but delayed it for the MSF group. Thus, flowering duration remained stable for the ESF group and was prolonged for the MSF group, and further prolonged the flowering duration of the community. There were no interactions between warming rates and precipitation addition on the community flowering phenology. A severe drought in a year significantly decreased the maximum number of community flowers the following year. Therefore, change in precipitation has a greater effect than warming on the community flowering phenology in the semi-arid alpine grassland.
... We found that burning advanced the start of growing period considerably, while also slightly advancing the end of growing period, resulting in a longer growing period in low aridity grasslands with relatively high precipitation. The advancement of the start of growing period may contribute to post-fire litter removal and optimal resource availability (Pyke, 2017;Zhou et al., 2020), and the advancement of the end of growing period may be due to an intrinsic process such as programmed cell death that controls the length of growing period (Steltzer and Post, 2009). Burning had little impact on the length of growing phase in the moderate-aridity grassland; and burning delayed it in the low precipitation grasslands. ...
Article
Plant phenology and growth rate are sensitive bio-indicators of climate change and anthropogenic disturbances. Fire is widespread in many ecosystems worldwide. Understanding how plant growth varies in its response to fire disturbance is critical for fire management. Despite the effects of fire on various aspects of plant ecology, such as the composition and growth of vegetation, little is known about the impact of fire on biomass production resulting from changes in functional group composition, plant phenology, and growth rate. Prescribed-burning of three types of grassland along an aridity gradient in Inner Mongolia, China, did not significantly affect species richness or the relative abundance of various functional groups across the three grasslands. Fire-induced advancement (∼3 weeks) and elongation (∼2 weeks) of growing periods increased perennial grass and community production in the low aridity grassland (aridity index, AI = 0.38). In contrast, marginal changes in phenology did not influence production in the moderate aridity grassland (AI = 0.27). Post-fire delayed and shortened growing period by ∼5 and 4 weeks respectively and thus reduced community production in the high aridity grassland (AI = 0.20). Post-fire plant growth rate was reduced by ∼44% in the low aridity grassland but was enhanced by 20–100% in the moderate and high aridity grasslands. The opposing effects of fire on growth rate vs. phenological responses largely negated any overall effect on community production. Our results indicate that phenology and growth rate rather than diversity were the primary contributors to the variation in production after fire. We provide new empirical evidence that prescribed-burning would not be a suitable management tool in extremely arid grasslands because it delays growing period and reduces production, both of which may influence grazing time and intensity. Our findings highlight the compensatory effects of plant phenology and growth rate on the regulation of biomass production.
... Phenological events, or the seasonal/periodic events in plant and animal life cycles, are considered highly sensitive to environmental variation and climate change (Friedl et al. 2014;Thackeray et al. 2016). Generally, in the northern hemisphere, events associated with spring appear to be occurring earlier and autumn events are delayed (Menzel and Fabian 1999;Steltzer and Post 2009). Both Western scientific and Indigenous knowledges suggest shifts in the timing of migration (caribou, Le Corre et al. 2017;migratory birds, Murphy-Klassen et al. 2005;Guyot et al. 2006), running and spawning of fish (Jacob et al. 2010), snow and ice dynamics (e.g., freeze-up, melt; Guyot et al. 2006;Laidler et al. 2009;Tam et al. 2013;Proverbs et al. 2021), and reproductive timing of animals and plants (Todd et al. 2011;Lynn et al. 2013). ...
Article
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Climate change disproportionately affects Indigenous Peoples because of strong connections between environmental, cultural, and spiritual well-being. While much of the global discourse surrounding climate change is founded in Western science, the holistic, place-based knowledge of Indigenous Peoples offers a complementary way of understanding and mitigating climate change impacts. The goal of this research was to elevate Anishinaabe concerns, observations, and perspectives about climate change impacts and future research needs. We organized a workshop called “Connecting Guardians in a Changing World” where participants shared concerns about animal and plant life cycles, water cycles and water quality, and impacts to ways of life, including reduced capacity to perform cultural practices and erosion of their knowledge. Participants highlighted the challenge of prioritizing a single impact of climate change, emphasizing that impacts to the environment and ways of life are interconnected. Participants also expressed the need for research and policy that move beyond interdisciplinarity to include intercultural philosophy and research that better reflects Indigenous worldviews and incorporates Indigenous methodologies. Moving forward, meaningful partnerships and opportunities for knowledge sharing should be prioritized in climate change discourse to ensure solutions are generated together, with all of the tools and knowledge available.
... (Ye et al, 2013 (Steltzer and Post, 2009) ( Cline, 2017 ) . (Shayanmehr et al, 2020b (Arora et al., 2013;Brown et al., 2011;Gupta et al., 2019;Lone et al., 2019;Lobell et al., 2010) ( ‫و‬ 0 ‫مدل‬ ) ‫رگرسیونی‬ ‫های‬ (Sarker et al ., 2012;Wei et al., 2014;Mahmood et al ., 2019;Doğan & Kan., 2019;Shayanmehr et al, 2020b) (Sarker et al.,2014;Shayanmehr et al, 2020a) . ...
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Extended Abstract Introduction Changes in the global climate have become one of the most crucial challenges facing agriculture in the twenty-first century. Climatic change is mainly characterized by a rise in greenhouse gas emissions and global average temperature as well as changes in precipitation levels and patterns. Undoubtedly, these changes affect the growth and productivity of agricultural production, and thus food security in many parts of the world like Iran. At present, supplying sufficient food and meeting food security in Iran relies on the management of climatic variables that affect agricultural production. Therefore, it is necessary to study the effects of climate change on agricultural production and food security in arid and semi-arid regions of this country such as the Khorasan region. Given the importance of this issue, the objective of the current study is to investigate climate change and its impacts on the yield and yield risk of selected crops, as well as on food security in the Khorasan region. Materials and Method The daily observed data for maximum temperature, minimum temperature, and precipitation is provided from the Meteorological Organization of Iran for 1961– 2010. The daily reanalysis data for the period (1961–2005) are obtained from the National Centers for Environmental Prediction (NCEP). The large-scale daily predictors for the CanESM2 model were developed by the CCCma for selected station. These data are used to predict climate parameters under three climatic scenarios (RCP 2.6, RCP 4.5 and 8.5) for 2030. This study used SDSM to downscale GCM-CanESM2 outputs. SDSM model, one of the most widely used models in the world, is applied to downscale future climate projections using the 26 predictors derived from a large-scale climate model. In the current study, a production function technique developed by Just and Pope is applied to investigate the effects of climate variables on the mean and variance of crop yields. This technique consists of two parts: the first component is relating to the yield levels and the second part is related to the yield variance. Results and discussion The results showed that maximum temperature, minimum temperature, and precipitation have a significant impact on the yield of the studied crops, so these factors will lead to a decrease in the production of irrigated wheat, irrigated barley, and dryland barley in 2030 compared to the base year. Findings indicate that per capita availability of wheat will decrease from 148.22 to 104.44, 107.51,109.83 and for barley will decrease from 74.28 to 47.94, 54.19, 62.79, and for potato will change from 26.44 to 25.37, 25.53, and 27.24 (kg per person) under climate scenarios RCP2.6, RCP4.5 and RCP8.5, respectively. In addition, the results show that climate change in 2030 will reduce the production of irrigated wheat, barley, and rain-fed barley, while these changes will improve the production of potatoes and rain-fed wheat. Furthermore, the findings of the study reveal that the improvement of technology will be able to reduce the negative effects of climate change on the production of vulnerable products. Also, due to population growth in this region as well as climate change, the per capita availability of crops in 2030 will decrease, which will increase the dependence of this region on other regions of the country and imports to meet food needs. Suggestion The results recommend that location-specific adaptation strategies be considered to mitigate the decrease in the yield of irrigated wheat, barley and rain-fed barley crops, and meet food security in the presence of climatic change. Investing in technology (new crop varieties, development irrigation coverage, and increased use of fertilizer) can be considered as an effective policy to reduce the negative effects of climate change on crop production. In addition, supporting population control and climate change mitigation policies can help achieve food security in Iran. JEL Classification: Q54 ،Q18 ،C10 ،D81. Keywords: Climatic variables, stochastic production function, yield risk, SDSM model.
... Isto significa que não será necessário cumprir-se na totalidade as previsões de aumento de temperatura feitas pelo IPCC para que as espécies sejam drasticamente afetadas. Considerando que o aumento da temperatura durante o último século já provocou mudanças fenológicas e alteração da distribuição geográfica em muitas espécies (ver Walther e col., 2002;Parmesan e Yohe, 2003;Genner e col., 2004;Nussey e col., 2005;Pearce-Higgins, 2005;Møller e col., 2006;Parmesan, 2006;Pörtner e Knust, 2007;Lenoir e col., 2008;le Roux e Mc-Geoch, 2008;Chen e col., 2009;Steltzer e Post, 2009), as consequências biológicas do aquecimento global poderão ser extraordinárias. ...
... We observed the delaying SOS mean trends and advancing EOS mean trends among daily-scale NDVI data and NDVI composites, which indicated opposite phenology trends (advancing SOS trends and delaying EOS trends) compared with former research [6,50,52,77,78]. We provide three explanations. ...
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The accurate evaluation of shifts in vegetation phenology is essential for understanding of vegetation responses to climate change. Remote-sensing vegetation index (VI) products with multi-day scales have been widely used for phenology trend estimation. VI composites should be interpolated into a daily scale for extracting phenological metrics, which may not fully capture daily vegetation growth, and how this process affects phenology trend estimation remains unclear. In this study, we chose 120 sites over four vegetation types in the mid-high latitudes of the northern hemisphere, and then a Moderate Resolution Imaging Spectroradiometer (MODIS) MCD43A4 daily surface reflectance data was used to generate a daily normalized difference vegetation index (NDVI) dataset in addition to an 8-day and a 16-day NDVI composite datasets from 2001 to 2019. Five different time interpolation methods (piecewise logistic function, asymmetric Gaussian function, polynomial curve function, linear interpolation, and spline interpolation) and three phenology extraction methods were applied to extract data from the start of the growing season and the end of the growing season. We compared the trends estimated from daily NDVI data with those from NDVI composites among (1) different interpolation methods; (2) different vegetation types; and (3) different combinations of time interpolation methods and phenology extraction methods. We also analyzed the differences between the trends estimated from the 8-day and 16-day composite datasets. Our results indicated that none of the interpolation methods had significant effects on trend estimation over all sites, but the discrepancies caused by time interpolation could not be ignored. Among vegetation types with apparent seasonal changes such as deciduous broadleaf forest, time interpolation had significant effects on phenology trend estimation but almost had no significant effects among vegetation types with weak seasonal changes such as evergreen needleleaf forests. In addition, trends that were estimated based on the same interpolation method but different extraction methods were not consistent in showing significant (insignificant) differences, implying that the selection of extraction methods also affected trend estimation. Compared with other vegetation types, there were generally fewer discrepancies between trends estimated from the 8-day and 16-day dataset in evergreen needleleaf forest and open shrubland, which indicated that the dataset with a lower temporal resolution (16-day) can be applied. These findings could be conducive for analyzing the uncertainties of monitoring vegetation phenology changes.
... Much less is known about what determines termination or total duration of insect activity (Forrest, 2016). Given extended growing seasons for many plant species (Steltzer & Post, 2009), it might be expected that insects also delay termination of adult insect activities in warmer regions. Longer growing seasons are increasing the number of generations per year (voltinism) of some insects (Altermatt, 2010a;Pöyry et al., 2011), but many species are obligate univoltine across their entire range, including warm regions (Forrest, 2016). ...
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Insect phenological lability is key for determining which species will adapt under environmental change. However, little is known about when adult insect activity terminates and overall activity duration. We used community-science and museum specimen data to investigate the effects of climate and urbanisation on timing of adult insect activity for 101 species varying in life history traits. We found detritivores and species with aquatic larval stages extend activity periods most rapidly in response to increasing regional temperature. Conversely, species with subterranean larval stages have relatively constant durations regardless of regional temperature. Species extended their period of adult activity similarly in warmer conditions regardless of voltinism classification. Longer adult durations may represent a general response to warming, but voltinism data in subtropical environments are likely underreported. This effort provides a framework to address the drivers of adult insect phenology at continental scales and a basis for predicting species response to environmental change.
... Previous studies have been conducted to examine vegetation phenology in temperate zones of China (Piao et al., 2006), including the Qinghai-Tibet Plateau , Xinjiang (Zhang et al., 2019), and Inner Mongolia Steppe (Ren et al., 2018), and in Eurasia (Zeng et al., 2011), Europe (Menzel and Fabian, 1999) and North America (Zhu et al., 2012). Many studies have demonstrated that the start of the growing season of vegetation has been advanced and the end postponed owing to global warming (Mo et al., 2011;Steltzer and Post, 2009). For example, Wang et al. (2015) pointed out that the advanced spring phenology was influenced by the increase in temperature in the winter and spring. ...
Article
Vegetation is highly sensitive to climate changes in arid regions. The relationship between vegetation and climate changes can be effectively characterized by vegetation phenology. However, few studies have examined the vegetation phenology and productivity changes in arid Central Asia (ACA). The vegetation phenological information of ACA was extracted using MODIS NDVI (Normalized Difference Vegetation Index) data, and the dynamics of vegetation phenological changes under spatiotemporal variations were quantitatively assessed. Moreover, the impacts of climate change on vegetation phenology and net primary productivity were analyzed by combining meteorological data with that of MODIS NPP (Net Primary Productivity) during the same period. The results demonstrated that the start of the season (SOS) of vegetation in the study was concentrated from mid-February to mid-April, while the end of the season (EOS) was concentrated from early October to mid-December. The length of growing season (LOS) ranged from 6 to 10 months. The SOS of vegetation was gradually postponed at a rate of 0.16 d·year⁻¹. The EOS advanced at a rate of 0.69 d·year⁻¹. The LOS was gradually shortened at a rate of 0.89 d·year⁻¹. For each per 1000 m increase in elevation, the SOS of vegetation was postponed by 12.40 d; the EOS advanced by 0.40 d, and the LOS was shortened by 11.70 d. For the impacts of climate changes on vegetation phenology and NPP, the SOS of vegetation phenology negatively correlated with temperature but positively correlated with precipitation and NPP. The EOS and LOS positively correlated with temperature but negatively with precipitation and NPP. Results indicated that the SOS was not moved ahead but was delayed, while the EOS advanced rather than being postponed under climate change. These results can offer new insights on the phenological response to climate change in arid regions and on non-systematic changes in phenology under global warming.
... Li XY, Zhu WQ, Li PX, Xie ZY, Zhao CL (2020 (Karl et al., 2015), 且高纬度及高海拔地区的气温升 幅更加明显 (李林等, 2002;Thomas et al., 2004;Peñuelas et al., 2013) (Menzel & Fabian, 1999;Ahas et al., 2002;徐 雨晴等, 2005;Wolkovich et al., 2012), 延迟了生物 学秋冬季 (张福春, 1995;Chmielewski & Rötzer, 2001;Steltzer & Post, 2009) (Johnson & Miyanishi, 2008;Tierney et al., 2010;Fitzpatrick et al., 2011;Blois et al., 2013), 它是将时间尺度下(尤其是过去或未来) 无法观测到的变化过程转换到空间尺度下进行模拟 或分析 (Blois et al., 2013 Table 3 Regression modeling results between each phenological event of Plantago asiatica and Taraxacum mongolicum and geographic factors across the Qinghai-Xizang Plateau ...
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Aims To analyse the feasibility of space-for-time method in predicting phenology shifts of Plantago asiatica and Taraxacum mongolicum on the Qinghai-Xizang Plateau, as well as revealing the phenological changes of the two herbaceous plants under climate warming. Methods The observed phenological data for Plantago asiatica and Taraxacum mongolicum from 10 sites on the Qinghai-Xizang Plateau during 2002-2011, as well as the meteorological data (i.e., daily mean air temperature) were collected. First, multiple linear regression models were bulit between geographic factors (longitude, latitude and altitude) and phenological events/annual mean temperature at different altitude gradients. Then, the longitude and latitude were kept to be unchanged, and the unary linear regression models between phenological events/annual mean temperature and altitude were built. Finally, the altitude was used as the “bridge” to indicate the relationship between the change of phenological events and the change of annual mean temperature. Important findings The temperature decreased with the increasing altitude (R2 > 0.89, p < 0.05), illustrating that changes of altitude gradients can be used to substitute for changes of annual mean temperature. The change in the simulated phenological events of the two herbaceous plants all showed a strong dependence on the change of altitude (R2 > 0.70, p < 0.05), which contributed the most among the geographic factors. Strong dependences were observed between the simulated phenological events and the simulated annual mean temperature (R2 > 0.93, p < 0.05), showing that phenological events could be predicted by the annual mean temperature with the space-for- time method. For Plantago asiatica, the first leaf date (FLD) and the first flowering date (FFD) occurred earlier with increasing annual mean temperature as 5.1 and 5.4 days per ℃, respectively, while the common leaf coloring date (LCD) occurred later as 4.8 days per ℃. The FLD and FFD of Taraxacum mongolicum advanced by 6.5 days and 7.8 days per ℃ of increase in the mean annual temperature while the LCD delayed by 6.7 days per ℃
... We did this for two reasons. First, the annual timing of the onset of, mid-point of, and full green-up of the plant community integrate species-specific life history responses to variation in weather and climate, and represent distinct ecological processes within the community, even though their annual timing may be correlated (Steltzer and Post, 2009). Second, the differential timing of occurrence of these three phenophases at the site represent potentially distinct phases of resource availability relative to the timing of resource demand by caribou and muskoxen at the site (Post, 2019). ...
Article
Alteration of local biodiversity by climate change may be especially impactful in the Arctic, where species richness is characteristically low and environmental conditions are changing rapidly. Two species of arctic large herbivores that survived rapid warming during the Pleistocene-Holocene transition, caribou and muskoxen, again face accelerated warming and changes in vegetation seasonality under contemporary climate change. While numerous studies have investigated the roles of weather and primary productivity in population dynamics of these species, opportunities for investigation of their dynamics in sympatric populations have been limited. We analyzed the population dynamics and offspring production of sympatric caribou and muskoxen at a study site in West Greenland over an 18-year period (2002–2019) during which the timing of spring green-up has advanced rapidly. In caribou, population growth rate and calf production were greater following warm winters but lower in years with earlier spring green-up. While calf production was highly variable, caribou abundance declined over the course of the study. In contrast, muskox population growth and calf production both increased following earlier springs. Moreover, muskox abundance increased over the course of the study, despite a negative association between their rate of increase and winter temperature, perhaps indicating that winter weather was less important than spring green-up timing in their dynamics. Hence, sympatric populations of these two herbivores displayed opposing demographic responses to winter weather and spring plant phenology at this shared location. These results emphasize the complexity of predicting large herbivore responses to climate change, and highlight the potential for impacts to species richness of large herbivore communities as the Arctic continues to warm.
... The maximum snow depth and timing of snow depletion have long been considered key drivers for which species live where across mountain watersheds and how much the plants can grow during the snowfree season (Billings, 1973;Walker et al., 1993). Less snow means less water for plant growth, though this also leads to earlier snow depletion dates and a lengthened snowfree season in which plants can grow (Steltzer and Post, 2009). The observed changes in mountain snowpack, including earlier snow depletion decouple water availability and demand for mountain plants (Wieder et al., 2017), and have likely driven changes in the timing of plant growth, and the rate and amount of plant growth across the URG. ...
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Study Region Upper Rio Grande Basin, United States. Study Focus Both measured and modeled hydrologic studies report warming-related changes in the hydrologic cycle. However, studies using measured data often rely on April 1 snow water equivalent (SWE) instead of peak SWE. To understand climate-related hydrograph shifts we investigate trends in maximum SWE, timing of maximum SWE and snow depletion and length of the snowmelt window using measured data with both linear regression and Mann-Kendall methods to provide an integrated understanding of the trends. New Hydrological Insights for the Region Of 16 locations with the longest data record (1980–2018) in the region, more than half had significant declines in maximum SWE. Regional trends using all sites collectively showed a decline in maximum SWE of -0.4 cm/year. Maximum SWE was earlier at 10–13 of 16 sites, depending upon method. Trends at individual locations show a wide range in maximum SWE advancement (18–48 days). Regional maximum SWE advanced three weeks. Snowpack depletion was similarly early at more than half the sites. Although snowmelt occurs earlier, there was no change in the snowmelt window (days between peak SWE and no snow). The reduced maximum SWE may relate to reduced snowfall, increased sublimation or lower albedo associated with dust. We describe the ecological and social impacts of these observed shifts in snow amount and runoff timing for headwaters communities, water compacts, mountain ecosystems, and riparian vegetation.
... Much less is known about what determines termination or total duration of insect activity (Forrest, 2016). Given extended growing seasons for many plant species (Steltzer and Post, 2009), it might be expected that insects also delay termination of adult insect activities in warmer regions. Longer growing seasons are increasing the number of generations per year (voltinism) of some insects (Altermatt, 2010a;Pöyry et al., 2011), but many species are obligate univoltine across their entire range, including warm regions (Forrest, 2016). ...
Preprint
Insect phenological lability is key for determining which species will adapt under environmental change. However, little is known about when adult insect activity terminates, and overall activity duration. We used community-science and museum specimen data to investigate the effects of climate and urbanization on timing of adult insect activity for 101 species varying in life history traits. We found detritivores and species with aquatic larval stages extend activity periods most rapidly in response to increasing regional temperature. Conversely, species with subterranean larval stages have relatively constant durations regardless of regional temperature. Multivoltine and univoltine species both extended their period of adult activity similarly in warmer conditions. Longer adult durations may represent a general response to warming, but voltinism data in subtropical environments is likely underreported. This effort provides a framework to address drivers of adult insect phenology at continental scales, and a basis for predicting species response to environmental change.
... In this meta-analysis, the plant growing season was extended by 8.2 days/°C, and such large changes under climate warming might represent the maximum within a limited plant lifetime (Steltzer & Post, 2009). ...
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Aim Understanding how plant phenophases respond to climate warming is key to prediction of future ecosystem dynamics. Although warming has lengthened the growing season of plants in most terrestrial ecosystems, little is known about the contribution of different phenophases to this extension. Location Global terrestrial ecosystems. Time period Data collected from 1979 to 2020. Major taxa studied Terrestrial plants. Methods Here, we conducted a global meta‐analysis, compiling 772 pairs of observational data from 42 warming manipulative experiments to investigate the temperature sensitivity (expressed as days per degree Celsius) of the durations of different phenophases across major natural terrestrial ecosystems. Results We found that the durations of flower bud, flowering and fruiting and the total reproductive phase did not exhibit any significant change in response to experimental warming across all terrestrial plants, although large variations in temperature sensitivity of the reproductive phenology existed. The temperature sensitivity of reproductive phases was influenced by the taxa of plants. Specifically, the flower bud duration of C4 plants had a higher temperature sensitivity than that of C3 plants, and the flowering duration in woody plants exhibited a marginally higher temperature sensitivity than in herbaceous plants. In contrast to the small responses of the reproductive phases, the growing season lengthened under experimental warming. The temperature sensitivity of the growing season length was strongly affected by the magnitude of warming, showing a slower lengthening of the growing season with larger increases in temperatures. Main conclusions These results suggest that, under future warmer climates, terrestrial plants will allocate more time to growth than to reproduction; however, the warming‐induced extension of the vegetative phase might slow down over time.
... This is because the direct response of oligophagous species to abiotic conditions altered by climate change may be tempered by their high dependence on their host plants 1 . Second, we expected larval woody feeders to show more pronounced changes in the seasonal timing and duration of the adult flight period compared to larval herb feeders since herbs can produce fresh shoots throughout the season while leaves of woody plants are available only for a short time period 8,31 and the newly flushing leaves of woody plants are increasingly appearing earlier in response to climate change 32 . Thus, woody feeders may track the earlier availability of fresh leaves of woody plants, and transition to the adult flighted stage earlier. ...
Article
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Diverse taxa have undergone phenological shifts in response to anthropogenic climate change. While such shifts generally follow predicted patterns, they are not uniform, and interspecific variation may have important ecological consequences. We evaluated relationships among species’ phenological shifts (mean flight date, duration of flight period), ecological traits (larval trophic specialization, larval diet composition, voltinism), and population trends in a butterfly community in Pennsylvania, USA, where the summer growing season has become warmer, wetter, and longer. Data were collected over 7–19 years from 18 species or species groups, including the extremely rare eastern regal fritillary Speyeria idalia idalia . Both the direction and magnitude of phenological change over time was linked to species traits. Polyphagous species advanced and prolonged the duration of their flight period while oligophagous species delayed and shortened theirs. Herb feeders advanced their flight periods while woody feeders delayed theirs. Multivoltine species consistently prolonged flight periods in response to warmer temperatures, while univoltine species were less consistent. Butterflies that shifted to longer flight durations, and those that had polyphagous diets and multivoltine reproductive strategies tended to decline in population. Our results suggest species’ traits shape butterfly phenological responses to climate change, and are linked to important community impacts.
... A fundamental requirement for the conservation of biodiversity is the identification of appropriate priorities, thereby allowing efficient allocation of the limited resources available (Singh 2002). Climate change has already caused, among other aspects, changes in cyclic and seasonal aspects of animal and plant life histories, and distributional patterns of both endothermic and ectothermic vertebrates (Steltzer & Post, 2009). Building a rigorous framework that includes predicting impacts of climate change on biomes and included species is currently one of the main challenges of science (Schwenk et al., 2009) Amphibians are among those vertebrates with substantial population regression or species extinction reported (Grenyer et al. 2006;Anthony et al. 2008), resulting in a worldwide phenomenon recognized as "amphibian declines". ...
Thesis
Los anfibios están entre los organismos más dependientes de las condiciones ambientales, estando limitados por características fisiológicas diferentes según sus estadios de vida (larvario o adulto). Además, nuestra área de estudio, el Mediterráneo Occidental, presenta una interesante historia paleogeográfica y paleo-climática, con la aparición y desaparición de barreras físicas o ambientales, derivadas estas últimas de los relativamente rápidos cambios climáticos producidos durante las glaciaciones. Es importante destacar que, en el actual escenario de Cambio Global, y más específicamente de Cambio Climático, esperamos cambios bruscos en el hábitat disponible para estas especias. Por esta razón, el estudio de la evolución del nicho, y sus perspectivas futuras, es una herramienta esencial para la conservación. En este trabajo abordamos este tema mediante una aproximación integrada dividida en dos bloques principales. Un primer bloque centrado en el modelado de nicho ambiental, incluyendo la evolución en la divergencia de este, escenarios futuros y condiciones pasadas que afectan la distribución actual de los anfibios en nuestra área de estudio. Y un segundo bloque que analiza las cuestiones fisiológicas que afectan a ambas fases de vida, e indagando en la respuesta de estos organismos para adaptarse a condiciones ambientales subóptimas. Nuestros resultados muestran que la divergencia de nicho ambiental tiene un papel clave en la evolución, que la estabilidad climática es un promotor de la diversidad en los anfibios del Mediterráneo Occidental y que el calentamiento climático antrópico afectará la disponibilidad de hábitat de estas especies de diferentes maneras, con reducciones en algunas y aumentos en otros. Esperamos que nuestros datos, unidos a futuras investigaciones, proporcionen información útil para la conservación de este grupo tan amenazado.
... The phenophases of most of the species were strongly correlated to DFSM and slightly less correlated to GDD with two exceptions, having nearly identical values. Photoperiod, which is proxied by DOY, is frequently referred to as an important cue in the timing of phenological events since it can help controlling extremely early or late development (Hülber et al. 2010;Steltzer and Post 2009). Our results though addressed us towards the hypothesis of the relatively poor relevance of photoperiod as a single factor in the prediction of the phenological cycle of alpine plants when faced with the chance of interannual variability. ...
Article
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The study of plant phenology has frequently been used to link phenological events to various factors, such as temperature or photoperiod. In the high-alpine environment, proper timing of the phenological cycle has always been crucial to overcome harsh conditions and potential extreme events (i.e. spring frosts) but little is known about the response dynamics of the vegetation, which could shape the alpine landscape in a future of changing climate. Alpine tundra vegetation is composed by an array of species belonging to different phytosociological optima and with various survival strategies, and snowbed communities are a relevant expression of such an extreme-climate adapted flora. We set eight permanent plots with each one in a snowbed located on the Cimalegna plateau in Northwestern Italy and then we selected 10 most recurring species among our plots, all typical of the alpine tundra environment and classified in 3 different pools: snowbed specialists, grassland species and rocky debris species. For 3 years we registered the phenophases of each species during the whole growing season using an adaptation of the BBCH scale. We later focused on the three most biologically relevant phenophases, i.e., flower buds visible, full flowering, and beginning of seed dispersion. Three important season-related variables were chosen to investigate their relationship with the phenological cycle of the studied species: (i) the Day Of Year (DOY), the progressive number of days starting from the 1st of January, used as a proxy of photoperiod, (ii) Days From Snow Melt (DFSM), selected to include the relevance of the snow dynamics, and (iii) Growing Degree Days (GDD), computed as a thermal sum. Our analysis highlighted that phenological development correlated better with DFSM and GDD than with DOY. Indeed, models showed that DOY was always a worse predictor since it failed to overcome interannual variations, while DFSM and marginally GDD were better suited to predict the phenological development of most of the species, despite differences in temperature and snowmelt date among the three years. Even if the response pattern to the three variables was mainly consistent for all the species, the timing of their phenological response was different. Indeed, species such as Salix herbacea and Ranunculus glacialis were always earlier in the achievement of the phenophases, while Agrostis rupestris and Euphrasia minima developed later and the remaining species showed an intermediate behavior. However, we did not detect significant differences among the three functional pools of species.
... Gill et al. 2015;Yang et al. 2015;Zhao et al. 2015;Liu et al. 2016b), which are attributed mainly to climate warming and would directly affect the carbon cycle and ecosystem productivity (Keeling et al. 1996;Myneni et al. 1997;Zhou et al. 2001;Piao et al. 2007;Peñuelas et al. 2009;Richardson et al. 2010;Keenan et al. 2014), as well as individual trees' own adaptation and survival ability (Kramer et al. 1996;Inouye 2008;Jentsch et al. 2009;Guo et al. 2015). Moreover, climate warming induced mismatches in timings of interdependent key life-cycle stages between different trophic levels may alter the complex interactions between species, and exert negative impacts on ecosystem structure and function (Parmesan 2006;Inouye 2008;Steltzer and Post 2009;Donnelly et al. 2011;Vitasse et al. 2011;Donnelly et al. 2015). ...
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Examining whether a phenophase occurrence date in the current year affects the same phenophase occurrence date in the following year is crucial for developing cross-year phenological prediction models. Here, we carried out correlation analyses between leaf unfolding start (LUS)/leaf fall end (LFE) dates in the current and following years for four dominant tree species in temperate northern China from 1981 to 2012. Then, we calculated the recurrence intervals of LUS and LFE between two adjacent years for each species. Moreover, we investigated temperature effects on LUS/LFE dates, growing season and non-growing season lengths. Results show that correlation coefficients between LUS/LFE dates in the current and following years are nonsignificant at most stations. The recurrence interval of a phenophase has slight interannual variation and correlates significantly (and negatively) with the phenophase occurrence date of the current year. Further analyses indicate that LUS dates correlate significantly (and negatively) with spring mean temperatures, while LFE dates correlate significantly (and positively) with autumn mean temperatures, but negatively with growing season mean temperatures. In addition, spring mean temperatures can influence growing season length by controlling LUS date but cannot influence the following non-growing season length. Similarly, autumn mean temperatures and growing season mean temperatures can influence the subsequent non-growing season length but cannot influence the growing season length of the following year. Our study highlights that recurrence interval and time restrictions in the effects of seasonal temperatures on phenophase dates are the main environmental causes of nonsignificant correlations between phenophase occurrence dates in the current and following years.
... As a consequence, snowmelt is found to be a critical period that influences nutrient mobilization, assimilation, and retention in terrestrial ecosystems (Brooks et al., 1998;Brooks and Williams, 1999;Grogan and Jonasson, 2003;Kielland et al., 2006;Campbell et al., 2007). Rising global air temperature has led to reductions in winter snowpack extent, earlier snowmelt dates, and altered growing season length in many mountainous catchments (Mote et al., 2005;Steltzer and Post, 2009;Harte et al., 2015;Sloat et al., 2015;Bormann et al., 2018;Hock et al., 2019;Prevéy et al., 2019). The ecological consequences of such environmental changes, however, are not well understood (Ernakovich et al., 2014). ...
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Soil microbial biomass can reach its annual maximum pool size beneath the winter snowpack and is known to decline abruptly following snowmelt in seasonally snow-covered ecosystems. Observed differences in winter versus summer microbial taxonomic composition also suggests that phylogenetically conserved traits may permit winter- versus summer-adapted microorganisms to occupy distinct niches. In this study, we sought to identify archaea, bacteria, and fungi that are associated with the soil microbial bloom overwinter and the subsequent biomass collapse following snowmelt at a high-altitude watershed in central Colorado, United States. Archaea, bacteria, and fungi were categorized into three life strategies (Winter-Adapted, Snowmelt-Specialist, Spring-Adapted) based upon changes in abundance during winter, the snowmelt period, and after snowmelt in spring. We calculated indices of phylogenetic relatedness (archaea and bacteria) or assigned functional attributes (fungi) to organisms within life strategies to infer whether phylogenetically conserved traits differentiate Winter-Adapted, Snowmelt-Specialist, and Spring-Adapted groups. We observed that the soil microbial bloom was correlated in time with a pulse of snowmelt infiltration, which commenced 65 days prior to soils becoming snow-free. A pulse of nitrogen (N, as nitrate) occurred after snowmelt, along with a collapse in the microbial biomass pool size, and an increased abundance of nitrifying archaea and bacteria (e.g., Thaumarchaeota, Nitrospirae). Winter- and Spring-Adapted archaea and bacteria were phylogenetically clustered, suggesting that phylogenetically conserved traits allow Winter- and Spring-Adapted archaea and bacteria to occupy distinct niches. In contrast, Snowmelt-Specialist archaea and bacteria were phylogenetically overdispersed, suggesting that the key mechanism(s) of the microbial biomass crash are likely to be density-dependent (e.g., trophic interactions, competitive exclusion) and affect organisms across a broad phylogenetic spectrum. Saprotrophic fungi were the dominant functional group across fungal life strategies, however, ectomycorrhizal fungi experienced a large increase in abundance in spring. If well-coupled plant-mycorrhizal phenology currently buffers ecosystem N losses in spring, then changes in snowmelt timing may alter ecosystem N retention potential. Overall, we observed that snowmelt separates three distinct soil niches that are occupied by ecologically distinct groups of microorganisms. This ecological differentiation is of biogeochemical importance, particularly with respect to the mobilization of nitrogen during winter, before and after snowmelt.
... Admittedly, our consideration of this mechanism does not rule out other non-mutually exclusive mechanisms. For example, the length of the plant growth period may be controlled by intrinsic processes such as programmed cell death (Lim et al. 2007;Steltzer & Post 2009), which may cause an earlier end of the plant growth following an earlier start. Furthermore, a reduction in pre-season soil moisture under warming may have contributed to the advance in the end of fast growth (Yang et al. 2019). ...
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Satellite data indicate significant advancement in alpine spring phenology over decades of climate warming, but corresponding field evidence is scarce. It is also unknown whether this advancement results from an earlier shift of phenological events, or enhancement of plant growth under unchanged phenological pattern. By analyzing a 35‐year dataset of seasonal biomass dynamics of a Tibetan alpine grassland, we show that climate change promoted both earlier phenology and faster growth, without changing annual biomass production. Biomass production increased in spring due to a warming‐induced earlier onset of plant growth, but decreased in autumn due mainly to increased water stress. Plants grew faster but the fast‐growing period shortened during the mid‐growing season. These findings provide the first in situ evidence of long‐term changes in growth patterns in alpine grassland plant communities, and suggest that earlier phenology and faster growth will jointly contribute to plant growth in a warming climate. Climate change reshapes plant growth patterns by shifting phenology earlier, enhancing growth rate, and shortening growth period in a Tibetan alpine grassland over 35 years. The changes in growth patterns alters seasonal, but not annual, biomass production.
... Climate change has already caused, among other aspects, changes in cyclic and seasonal aspects of animal and plant life histories, and distributional patterns of both endothermic and ectothermic vertebrates [64]. Building a rigorous framework that includes predicting impacts of climate change on biomes and included species is currently one of the main challenges of science [60]. ...
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One common approach to assigning conservation priorities during the current biodiversity crisis is to identify and direct efforts to high profile, vulnerable taxa, and important biodiversity areas. We addressed the first issue by assessing the comparison between conservation status and habitat suitability under differing climate change scenarios for sixteen species of five amphibian families (Pelobatidae, Bufonidae, Alytidae, Hylidae and Ranidae) distributed on both sides of the Gibraltar Strait, hoping to identify potentially threatened species under climatic change scenarios which are not considered at risk presently. We have addressed this with an environmental niche modelling (ENM) algorithm (MaxEnt) and projecting the outputs in four future climatic change scenarios. Our results demonstrate that climatic niches of some species may currently match their conservation category, with Pelobates varaldii having the narrowest distribution and being the more endangered species, but not all responses to predicted climatic change scenarios are related to conservation status. Some suggest notable changes in potential climatic habitats, with both substantial increase (7 species) and decrease (5 species) represented. Threatened species such as Pelobates varaldii could be climatically favored whereas currently more abundant species could maintain, increase, or reduce their habitat distribution. These results have implications for current conservation strategies, and suggest that this approach deserves consideration as part of any species or habitat conservation strategy in the future.
... For example, P. idas (−20.21) was recorded earlier at higher elevation and cooler conditions. A possible explanation could be earlier availability of food resources at higher elevations: Similarly to butterflies, plants also have shortened their life cycles and advance their flowering and seed production as the climate has warmed(Steltzer & Post, 2009).Alternatively, negative species patterns might be regulated by an evolutionary adaptability to warmer climate, through an increased voltinism, despite the cooler local conditions at high elevation. An earlier appearance and prolonged flight period within areas above the timberline has also been reported for an alpine butterfly species F I G U R E 1 Partial residuals and prediction lines showing effects of elevation on (a) mean date (days since 1 January, 1 January = 1) and (b) duration of the flight period (standard deviation about the mean date). ...
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Abstract Inferring species' responses to climate change in the absence of long‐term time series data is a challenge, but can be achieved by substituting space for time. For example, thermal elevational gradients represent suitable proxies to study phenological responses to warming. We used butterfly data from two Mediterranean mountain areas to test whether mean dates of appearance of communities and individual species show a delay with increasing altitude, and an accompanying shortening in the duration of flight periods. We found a 14‐day delay in the mean date of appearance per kilometer increase in altitude for butterfly communities overall, and an average 23‐day shift for 26 selected species, alongside average summer temperature lapse rates of 3°C per km. At higher elevations, there was a shortening of the flight period for the community of 3 days/km, with an 8.8‐day average decline per km for individual species. Rates of phenological delay differed significantly between the two mountain ranges, although this did not seem to result from the respective temperature lapse rates. These results suggest that climate warming could lead to advanced and lengthened flight periods for Mediterranean mountain butterfly communities. However, although multivoltine species showed the expected response of delayed and shortened flight periods at higher elevations, univoltine species showed more pronounced delays in terms of species appearance. Hence, while projections of overall community responses to climate change may benefit from space‐for‐time substitutions, understanding species‐specific responses to local features of habitat and climate may be needed to accurately predict the effects of climate change on phenology.
... There is considerable evidence that rising temperatures have advanced the onset of vegetation greening in spring (i.e., start of season, SOS), especially in the middle and high geographical latitudes (Jeong et al., 2011;Menzel et al., 2006;Myneni et al., 1997;Steltzer and Post, 2009). Changes in the timing and duration of SOS are essential drivers of the evolution of terrestrial ecosystems structure and functioning (Barichivich et al., 2013;Schwartz, 1998), influencing the regional and global cycling of carbon and water, nutrients, and energy budget (Barr et al., 2004;Filella, 2001, 2009). ...
... Vegetation phenology describes the timing of plant life-cycles events connected to climate (Menzel et al., 2006;Schwartz et al., 2006) including recurring transitions of vegetation growth and senescence processes (Delpierre et al., 2009;Chuine et al., 2010). Climate change strongly affects terrestrial plant life cycles (Steltzer and Post, 2009) by altering the onset and dura-tion of vegetation phenological events. In return, changes in vegetation phenology can regulate climate by altering the energy, water, and carbon exchanges between land surfaces and the atmosphere (Zhang et al., 2006;Richardson et al., 2010). ...
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Vegetation indices (VIs) from satellite remote sensing have been extensively applied to analyze the trends of vegetation phenology. In this paper, the NDVI (normalized difference vegetation index) and SR (simple ration), which are calculated from the same spectral bands of MODIS data with different mathematical expressions, were used to extract the start date (SOS) and end date (EOS) of the growing season in northern China and Mongolia from 2000 to 2015. The results show that different vegetation indices would lead to differences in vegetation phenology especially in their trends. The mean SOS from NDVI is 15.5 d earlier than that from SR, and the mean EOS from NDVI is 13.4 d later than that from SR. It should be noted that 16.3% of SOS and 17.2% of EOS derived from NDVI and SR exhibit opposite trends. The phenology dates and trends from NDVI are also inconsistent with those of SR among various vegetation types. These differences based on different mathematical expressions in NDVI and SR result from different resistances to noise and sensitivities to spectral signal at different stage of growing season. NDVI is prone to be effected more by low noise and is less sensitive to dense vegetation. While SR is affected more by high noise and is less sensitive to sparse vegetation. Therefore, vegetation indices are one of the uncertainty sources of remote sensing-based phenology, and appropriate indices should be used to detect vegetation phenology for different growth stages and estimate phenology trends.
... The timing and duration of the growing season is shifting due to altered seasonal cues for plant development (Sparks and Menzel 2002, Walther et al. 2002, Linderholm 2006. Growing season length for a plant community is determined by individual species' annual life cycles; it is characterized by the onset of greening for the first species, through leaf expansion and full canopy development, to the onset of leaf senescence and total leaf fall for the last species (Steltzer and Post 2009). In the spring, onset of plant growth is occurring earlier relative to previous decades in many regions (Zhou et al. 2001, Buitenwerf et al. 2015. ...
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The timing and duration of the plant growing season and its period of peak activity have shifted globally in response to climate change. These changes alter the period of maximum and potential total carbon uptake, especially in highly seasonal environments such as the Arctic. Earlier plant growth has been observed, and if plant senescence remains the same or is delayed, growing season extension will likely lead to greater carbon uptake and growth. We used phenology data from a multifactor climate change experiment to examine how altered seasonality influences the timing and rate‐of‐senescence and to compare direct observations of individual plant senescence with mathematical models of onset‐of‐senescence based on near‐surface remote sensing. Our three‐year experiment in an Arctic tundra ecosystem altered plant microclimates through factorial warming and earlier snowmelt treatments. We found that (1) early snowmelt and warmer temperatures led to earlier remotely sensed onset‐of‐senescence, but did not alter the rate‐of‐senescence, (2) the timing of color change for individual vascular plants did not change in response to the treatments, leading to a mismatch with remotely sensed phenology, and (3) cumulative, phenologically dependent microclimate metrics (e.g., soil cold degree‐days) best predicted the onset‐of‐senescence. Our study highlights the complexity of observing and understanding controls over phenological shifts that affect plant growth and consequently ecosystem functions. Experimental studies that include multiple approaches to observe and model phenological changes and microclimate are critical to develop phenological forecasting models.
... The finding of greater temperature sensitivity of late-flowering species differs from the results of many studies conducted at lower latitudes and altitudes 6,18,19,49 . Studies from warmer biomes found that early-flowering species often advance phenological events more in response to warmer temperatures than late-flowering species 1,[16][17][18][19]50,51 . Mid-and late-season moisture limitation probably plays a greater role in structuring the phenology of plants in warmer ecosystems 52 . ...
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In the version of this Article originally published, the following sentence was missing from the Acknowledgements: “This work was supported by the Norwegian Research Council SnoEco project, grant number 230970”. This text has now been added.
... Climatic warming and elevated CO 2 is expected to create a potential for higher forest production in the boreal forest regions in Europe (Bergh et al. 2003;Reyer et al. 2014). Phenology responses represent some of the factors affecting this potential, for instance whether or not the growing season is extended (Steltzer and Post 2009). Growth onset in spring is expected to be advanced by increasing temperatures (Menzel et al. 2006), while the effect on growth cessation depends on species and ecotype (Hänninen and Tanino 2011). ...
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Temperature during seed maturation can induce an epigenetic memory effect in growth phenology of Norway spruce (Picea abies (L.) Karst.) that lasts for several years. To quantify the epigenetic modifications induced by natural climatic variation, common garden experiments with plants originating from different provenances and seed years were performed. Plants from warmer seed years showed delayed phenology with later bud flush, bud set and growth cessation. This effect was quantified by linear models of phenology traits as a function of climate indices for the origin and seed year of the plants. Significant effects of the temperature during seed production (seed year) was found for the bud set in seedlings in their first growing season and for bud flush and growth cessation in the 7th-8th growing season from seed. The models suggest that growth start and growth cessation are delayed 0.7–1.8 days per 100 additional degree days experienced by the seed during embryo development and seed maturation. Models that include factors that are known to induce epigenetic effects could be used to better predict future performance of forest reproductive material.
... Under such temperature-limited conditions, growth is known to be highly sensitive to ongoing climate change (Beniston, 2003;IPCC, 2013;Soja et al., 2007). Recent studies indicated that warmer and drier conditions in temperature-limited ecosystems (at high elevations and latitudes) are altering the forest composition and the timing and duration of both primary and secondary growth (e.g., Allen et al., 2010;Esper & Schweingruber, 2004;Meier, Lischke, Schmatz, & Zimmermann, 2012;Peters, Klesse, Fonti, & Frank, 2017;Rigling et al., 2013;Steltzer & Post, 2009). Subsequently, these changes have consequences for the terrestrial biogeochemical cycles and the global climate system (Bonan, 2008;Myneni et al., 2001). ...
Article
We used four years of sap flow measurements to elucidate intra‐ and inter‐specific variability of gs in Larix decidua Mill. and Picea abies (L.) Karst along an elevational gradient and contrasting soil moisture conditions. Site‐ and species‐specific gs response to main environmental drivers were examined, including vapour pressure deficit, air temperature, solar irradiance and soil water potential. Our results indicate that maximum gs of L. decidua is >2 times higher, shows a more plastic response to temperature, and downregulates gs stronger during atmospheric drought compared to P. abies. These differences allow L. decidua to exert more efficient water use, adjust to site‐specific thermal conditions, and reduce water loss during drought episodes. The stronger plasticity of gs sensitivity to temperature and higher conductance of L. decidua compared to P. abies provide new insights into species‐specific water‐use strategies, which affect species’ performance and should be considered when predicting terrestrial water dynamics under future climatic change.
... The finding of greater temperature sensitivity of late-flowering species differs from the results of many studies conducted at lower latitudes and altitudes 6,18,19,49 . Studies from warmer biomes found that early-flowering species often advance phenological events more in response to warmer temperatures than late-flowering species 1,[16][17][18][19]50,51 . Mid-and late-season moisture limitation probably plays a greater role in structuring the phenology of plants in warmer ecosystems 52 . ...
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Advancing phenology is one of the most visible effects of climate change on plant communities, and has been especially pronounced in temperature-limited tundra ecosystems. However, phenological responses have been shown to differ greatly between species, with some species shifting phenology more than others. We analysed a database of 42,689 tundra plant phenological observations to show that warmer temperatures are leading to a contraction of community-level flowering seasons in tundra ecosystems due to a greater advancement in the flowering times of late-flowering species than early-flowering species. Shorter flowering seasons with a changing climate have the potential to alter trophic interactions in tundra ecosystems. Interestingly, these findings differ from those of warmer ecosystems, where early-flowering species have been found to be more sensitive to temperature change, suggesting that community-level phenological responses to warming can vary greatly between biomes.
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Plant phenology in terrestrial ecosystems, especially in the Northern Hemisphere, is expected to change owing to the projected increasing frequency and intensity of climate extremes in the context of global warming. Although such changes under mean climate change have been extensively reported in the literature, little is known about the impacts of climate extremes. In this study, climatic changes and their effects on plant phenology were characterized using long-term climatic and phenological data from the start and end of the growing season (SOS and EOS, respectively) from 2005 to 2020 for Stipa baicalensis, a dominant species in a temperate meadow steppe. The results showed that the temperature, including the mean and minimum temperatures, and extreme warm indices significantly increased; however, annual precipitation, and the frequency of extreme cold and precipitation events decreased. The SOS of S. baicalensis was initially earlier and later, whereas the EOS trended to be delayed. However, the growing season (LOS) was slightly prolonged. Compared with the indices under mean temperature, the pre-season (before SOS or EOS) minimum temperature dominantly affected SOS and EOS, whereas the mean and extreme precipitation slightly affected them. Furthermore, the findings showed that plant phenology responded to extreme temperatures quicker and stronger than mean temperatures. This study provides insight into how key extreme climatic factors could affect plant phenophases and improve and refine the phenological model. This could also be useful in enhancing grassland ecosystem management and sustainable development.
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Seasonal snow is sensitive to climate change, and is always taken as a signal of local climate changes. As changes in snow differ locally in their characteristics, it is necessary to detect the effects of snow on different land cover types. The middle and high latitudes of the Northern Hemisphere are located in a vast area of seasonal snow, experiencing snow accumulation and snowmelt stages each year. This study found that selected land cover types (open shrubland, evergreen needleleaf forest, and mixed forest) possess unique relationship curves between the snow cover fraction and snow depth. This has resulted in the northward shrinking of open shrubland and expansion of evergreen needleleaf forest and mixed forest, thereby further modulating local ecological systems. However, such changes in the snow process are not reproduced well by model parameterizations, and a faster melting process in the snowmelt stage will occur owing to the effects of global warming not being properly considered in such parametrization schemes. This inability to properly simulate the change in the snow process will affect our understanding of the ecological impacts of snowmelt in spring.
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Vegetation phenology is a sensitive indicator of climate change, and can help understand the response of vegetation cycles to climate, which is important for understanding the impact of global climate change on terrestrial ecosystems. In this study, based on the enhanced vegetation index (EVI) time-series data, derived from the moderate-resolution imaging spectroradiometer (MODIS) data, the climate parameters were extracted using the Savitzky–Golay (S–G) filtering method to explore the spatial and temporal variation characteristics of the vegetation phenology in an agro-pasture ecotone in China, from 2000 to 2020. In addition, the response characteristics of the vegetation phenology to the climate elements (temperature and precipitation) were also analyzed. The results showed the following: (1) The start of the growing season (SOS) was widely advanced, and that was caused by climate change. The end of the growing season (EOS) was delayed, and the length of the growing season (LOS) was gradually extended with a large interannual fluctuation in the SOS and the LOS in the region; (2) the SOS showed significant negative correlations with the air temperature and precipitation. Precipitation was mainly positively correlated with the EOS, but there was no significant difference in the correlation between temperature and the EOS. In general, pre-season precipitation is the main driver of the vegetation phenology, while the influence of temperature on the phenology is less obvious; (3) in the semi-arid area and arid area, the phenology was mainly influenced by precipitation. The response of the vegetation phenology to the temperatures in different temperature zones was found to be regular, showing high spatial differences. In general, the higher the cumulus temperature, the lower the negative effect of the temperature on both the SOS and EOS. These results may provide new reference to study the non-systematic changes of the vegetation phenology in response to climate change.
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The ongoing phenological changes in vegetation on the Qinghai–Tibetan Plateau could modify land surface and atmospheric processes. In this Review, we summarize these changes, their drivers and the resulting impacts. The start of the growing season advanced by 9.4 ± 2.2 days during 1982–1999 and 8.3 ± 2.0 days over 2000–2020, and the end of season delayed by 8.2 ± 1.9 days during 2000–2020. The main identified drivers of these changes are warming temperatures and increasing precipitation, but their impacts vary substantially across the Qinghai–Tibetan Plateau. Other factors, such as grazing and nitrogen deposition, also potentially influence phenological changes, but these relationships are poorly constrained. In manipulation experiments, grazing and nitrogen addition have no individual effects on most phenophase timings at the population level, but nitrogen addition markedly delays flowering. Additionally, there are carry-over effects between phenophases that control subsequent temperature and precipitation responses. Phenological changes in turn could alter species interactions, modulate carbon and water cycling, and affect Asian monsoons and spring rainfall over eastern China, but evidence of these interactions is limited. Harmonization of remote-sensing-based and in situ observations, and simultaneous testing of both biotic and abiotic factors, are needed for a mechanistic understanding of Qinghai–Tibetan Plateau phenology dynamics.
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The phenology of vegetation, namely leaf-out and senescence, can influence the Earth’s climate over regional spatial scales and long time periods (e.g., over 30 years or more), in addition to microclimates over local spatial scales and shorter time periods (weeks to months). However, the effects of flowers on climate and microclimate are unknown. We investigate whether flowers can influence light reflected by the land surface and soil microclimate in a subalpine meadow. We conducted a flower removal experiment with a common sunflower species, Helianthella quinquenervis, for 3 years (2015, 2017, and 2019). The flower removal treatment simulates the appearance of the meadow when Helianthella flowers earlier under climate change and loses its flowers to frost (other plant structures are not damaged by frost). We test the hypotheses that a reduction in cover of yellow flowers leads to a greener land surface, lower reflectance, warmer and drier soils, and increased plant water stress. Flower removal plots are greener, reflect less light, exhibit up to 1.2 °C warmer soil temperatures during the warmest daylight hours, and contain ca. 1% less soil moisture compared to controls. However, soils were warmer in only 2 of the 3 years, when flower abundance was high. Helianthella water use efficiency did not differ between removal and control plots. Our study provides evidence for a previously undocumented effect of flowers on soil microclimate, an effect that is likely mediated by climate change and flowering phenology. Many anthropogenic environmental changes alter landscape albedo, all of which could be mediated by flowers: climate change, plant invasions, and agriculture. This study highlights how further consideration of the effects of flowers on land surface albedo could improve our understanding of the effects of vegetation on microclimate.
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Declines of wild bees together with unsustainably high losses of managed colonies and worsening bee health have become global issues. Southwest Nigeria is a tropical rainforest biome. It is one of the most biologically diverse ecosystems, with the changing agricultural development and climate overwhelmingly impacting it. The impact is also significant on beekeeping vis: colony establishment, health and productivity of the native bees the West African honeybees, Apis mellifera adansonii Latreille (Hymenoptera: Apidae). This bee was once described as strongly adaptive to the tropical rainforest, productive, hygienic and immuned to pathogenic infections. This study was carried out between December, 2015 to December, 2018 to determine the stress factors associated with colony establishment, health and productivity of the bee colonies. Four states were purposively selected in the Southwest Nigeria. Some beekeepers were selected, sampling and colony observations were made in selected apiaries and laboratory investigations were conducted. Results indicated decline in colony numbers and honey production from 2016 to 2018. Out of 96 inspected colonies, 16 (16.67%) colonies have become weakened or lost due to bee pests and diseases this is greater than losses recorded due to other factors. Similarly, infestation with small hive beetles (SHB) across the region is 82(85.43 ± 0.01%) greater than 67(69.93 ± 2.08) (Mean ± SD) recorded for Galleria mellonella infestation. SHB infestation were significantly different across the states (P = 0.005, p < 0.05). The mean levels of Gluthathion-S-Transferase (GST) detoxifier chemical signal in the tissues of bees tested in the colonies for the three years were higher than the normal value for bees. The climate change, and the adaptation policy and development such as agricultural intensification programme adopted is a relevant and sustainable mitigation tool but with a pervasive influence on beekeeping, honeybee health, population and productivity.
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Significance Climate change is altering the seasonal environmental conditions to which animals have adapted, but the outcome may differ between seasons for a particular species. Demographic responses therefore need disentangling on a seasonal basis to make accurate forecasts. Our study shows that climate change is causing seasonally divergent demographic responses in a hibernating mammal. Continued climate change will likely have a positive effect on summer survival but a negative effect on winter survival. This potentially has wide-ranging consequences across other species occupying temperate to more extreme arctic and alpine habitats, which are also where the most rapid changes in climate are observed.
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Vegetation phenology is undergoing profound changes in response to the recent increases in the intensity and frequency of drought events. However, the mechanisms by which drought affects the start of the growing season (SGS) are poorly understood particularly in arid and semi-arid regions. Here, we identified varying degrees of preseason drought events and analyzed the sensitivity of the SGS to preseason drought across the Northeast China Transect (NECT). Our results showed that drought caused a delayed SGS in grassland ecosystems, but an advanced SGS within forest ecosystems. These contrasting responses to preseason drought reflected different adaptive strategies between vegetation types. The SGS was shown to be highly sensitive to short timescales drought (1–3 months) in semi-arid grasslands where annual precipitation is 200–300 mm (i.e. SAGE200–300). Biomes within this region were found to be most vulnerable out of all the ecosystems to drought. Given the frequent nature of droughts in the mid-latitudes, a drought early warning system was recommended accompanied by improved modeling of how the SGS will be affected by intensified drought under future climate change.
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Large‐scale warming will alter multiple local climate factors in alpine tundra, yet very few experimental studies examine the combined yet distinct influences of earlier snowmelt, higher temperatures and altered soil moisture on alpine ecosystems. This limits our ability to predict responses to climate change by plant species and communities. To address this gap, we used infrared heaters and manual watering in a fully factorial experiment to determine the relative importance of these climate factors on plant flowering phenology, and response differences among plant functional groups. Heating advanced snowmelt and flower initiation, but exposed plants to colder early‐spring conditions in the period prior to first flower, indicating that snowmelt timing, not temperature, advances flowering initiation in the alpine community. Flowering duration was largely conserved; heating did not extend average species flowering into the latter part of the growing season but instead flowering was completed earlier in heated plots. Although passive warming experiments have resulted in warming‐induced soil drying suggested to advance flower senescence, supplemental water did not counteract the average species advance in flowering senescence caused by heating or extend flowering in unheated plots, and variation in soil moisture had inconsistent effects on flowering periods. Functional groups differed in sensitivity to earlier snowmelt, with flower initiation most advanced for early‐season species and flowering duration lengthened only for graminoids and forbs. We conclude that earlier snowmelt, driven by increased radiative heating, is the most important factor altering alpine flowering phenology. Studies that only manipulate summer temperature will err in estimating the sensitivity of alpine flowering phenology to large‐scale warming. The wholesale advance in flowering phenology with earlier snowmelt suggests that alpine communities will track warming, but only alpine forbs and graminoids appear able to take advantage of an extended snow‐free season.
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Variations in the amplitude and timing of the seasonal cycle of atmospheric CO2 have shown an association with surface air temperature consistent with the hypothesis that warmer temperatures have promoted increases in plant growth during summer1 and/or plant respiration during winter2 in the northern high latitudes. Here we present evidence from satellite data that the photosynthetic activity of terrestrial vegetation increased from 1981 to 1991 in a manner that is suggestive of an increase in plant growth associated with a lengthening of the active growing season. The regions exhibiting the greatest increase lie between 45°N and 70°N, where marked warming has occurred in the spring time3 due to an early disappearance of snow4. The satellite data are concordant with an increase in the amplitude of the seasonal cycle of atmospheric carbon dioxide exceeding 20% since the early 1970s, and an advance of up to seven days in the timing of the drawdown of CO2 in spring and early summer1. Thus, both the satellite data and the CO2 record indicate that the global carbon cycle has responded to interannual fluctuations in surface air temperature which, although small at the global scale, are regionally highly significant.
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The northern high latitudes have warmed by about 0.8°C since the early 1970s, but not all areas have warmed uniformly [Hansen et al., 1999]. There is warming in most of Eurasia, but the warming rate in the United States is smaller than in most of the world, and a slight cooling is observed in the eastern United States over the past 50 years. These changes beg the question, can we detect the biotic response to temperature changes? Here we present results from analyses of a recently developed satellite-sensed normalized difference vegetation index (NDVI) data set for the period July 1981 to December 1999: (1) About 61% of the total vegetated area between 40°N and 70°N in Eurasia shows a persistent increase in growing season NDVI over a broad contiguous swath of land from central Europe through Siberia to the Aldan plateau, where almost 58% (7.3×106km2) is forests and woodlands; North America, in comparison, shows a fragmented pattern of change in smaller areas notable only in the forests of the southeast and grasslands of the upper Midwest, (2) A larger increase in growing season NDVI magnitude (12% versus 8%) and a longer active growing season (18 versus 12 days) brought about by an early spring and delayed autumn are observed in Eurasia relative to North America, (3) NDVI decreases are observed in parts of Alaska, boreal Canada, and northeastern Asia, possibly due to temperature-induced drought as these regions experienced pronounced warming without a concurrent increase in rainfall [Barber et al., 2000]. We argue that these changes in NDVI reflect changes in biological activity. Statistical analyses indicate that there is a statistically meaningful relation between changes in NDVI and land surface temperature for vegetated areas between 40°N and 70°N. That is, the temporal changes and continental differences in NDVI are consistent with ground-based measurements of temperature, an important determinant of biological activity. Together, these results suggest a photosynthetically vigorous Eurasia relative to North America during the past 2 decades, possibly driven by temperature and precipitation patterns. Our results are in broad agreement with a recent comparative analysis of 1980s and 1990s boreal and temperate forest inventory data [United Nations, 2000].
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Significant changes in physical and biological systems are occurring on all continents and in most oceans, with a concentration of available data in Europe and North America. Most of these changes are in the direction expected with warming temperature. Here we show that these changes in natural systems since at least 1970 are occurring in regions of observed temperature increases, and that these temperature increases at continental scales cannot be explained by natural climate variations alone. Given the conclusions from the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report that most of the observed increase in global average temperatures since the mid-twentieth century is very likely to be due to the observed increase in anthropogenic greenhouse gas concentrations, and furthermore that it is likely that there has been significant anthropogenic warming over the past 50 years averaged over each continent except Antarctica, we conclude that anthropogenic climate change is having a significant impact on physical and biological systems globally and in some continents.
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The urban heat island effect, classically associated with high impervious surface area (ISA), low vegetation fractional cover (Fr), and high land surface temperature (LST), has been linked to changing patterns of vegetation phenology, especially spring growth. In this study, a collaboration with the Global Learning and Observations to Benefit the Environment (GLOBE) program, we investigated the effect of the urban environment on the timing of leaf budburst of native deciduous trees in seven cities: Asia (Tokyo, Japan; Bangkok and Korat, Thailand), Europe (Jyväskylä, Finland; Bishkek, Kyrgyzstan), Africa (Dakar, Senegal), and North America (Fairbanks, Alaska). The cities differed not only in population size but also in climate and vegetation type. Using Landsat satellite imagery from each city, we calculated LST, Fr, and ISA, and classified sites within each study area as rural or urban. The timing of leaf flushing, measured by students using GLOBE budburst protocols, was statistically different within all cities, with absolute differences ranging from 1 to 23 days. We assessed the classic urban phenology paradigm, which proposes higher LST, lower Fr, and earlier budburst in urban areas of temperate cities. Of the four temperate cities, Tokyo followed the classic paradigm, but no other city demonstrated consistent support. Urban budburst was advanced in three of the four temperate cities, but in only one of the three tropical cities. Results suggest that while vegetation phenology is consistently different between urban and rural areas, a uniform paradigm based on the explanatory variables in this study did not emerge. Although not testable here, it is likely that alterations to chilling requirements in temperate climates and humidity in tropical climates may also influence observed budburst differences.
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Shifting plant phenology (i.e., timing of flowering and other developmental events) in recent decades establishes that species and ecosystems are already responding to global environmental change. Earlier flowering and an extended period of active plant growth across much of the northern hemisphere have been interpreted as responses to warming. However, several kinds of environmental change have the potential to influence the phenology of flowering and primary production. Here, we report shifts in phenology of flowering and canopy greenness (Normalized Difference Vegetation Index) in response to four experimentally simulated global changes: warming, elevated CO(2), nitrogen (N) deposition, and increased precipitation. Consistent with previous observations, warming accelerated both flowering and greening of the canopy, but phenological responses to the other global change treatments were diverse. Elevated CO(2) and N addition delayed flowering in grasses, but slightly accelerated flowering in forbs. The opposing responses of these two important functional groups decreased their phenological complementarity and potentially increased competition for limiting soil resources. At the ecosystem level, timing of canopy greenness mirrored the flowering phenology of the grasses, which dominate primary production in this system. Elevated CO(2) delayed greening, whereas N addition dampened the acceleration of greening caused by warming. Increased precipitation had no consistent impacts on phenology. This diversity of phenological changes, between plant functional groups and in response to multiple environmental changes, helps explain the diversity in large-scale observations and indicates that changing temperature is only one of several factors reshaping the seasonality of ecosystem processes.
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Because the flowering and fruiting phenology of plants is sensitive to environmental cues such as temperature and moisture, climate change is likely to alter community-level patterns of reproductive phenology. Here we report a previously unreported phenomenon: experimental warming advanced flowering and fruiting phenology for species that began to flower before the peak of summer heat but delayed reproduction in species that started flowering after the peak temperature in a tallgrass prairie in North America. The warming-induced divergence of flowering and fruiting toward the two ends of the growing season resulted in a gap in the staggered progression of flowering and fruiting in the community during the middle of the season. A double precipitation treatment did not significantly affect flowering and fruiting phenology. Variation among species in the direction and magnitude of their response to warming caused compression and expansion of the reproductive periods of different species, changed the amount of overlap between the reproductive phases, and created possibilities for an altered selective environment to reshape communities in a future warmed world. • climate change • global warming • precipitation
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The response of plants to temperature has gained renewed interest as researchers speculate on the biotic response to climate change. It is of particular interest in the Arctic, due to recent warming trends and anticipated continued warming for the region. This long-term, multispecies study confirms that changes in temperature affect the functioning of plants in their natural environment. It also demonstrates that the influence of temperature should be considered in the context of natural variability within a given location. The study examined natural temperature gradients, interannual climate variation, and experimental warming at sites near Barrow (71®18' N, 156°40' W) and Atqasuk (70°29' N, 157°25' W) in northern Alaska, USA. At each of the four sites, 24 plots were experimentally warmed for 5-7 years with small, open-top chambers, and plant growth and phenology were monitored; an equal number of unmanipulated control plots were monitored. The response of seven traits from 32 plant species occurring in at least one site is reported when there were at least three years of recordings. Plants responded to temperature in 49% of the measured traits of a species in a site. The most common response to warming was earlier phenological development and increased growth and reproductive effort. However, the total response of a species, for all traits examined, was individualistic and varied among sites. In 14% of the documented responses, the plant trait was correlated with thawing degree-day totals from snowmelt (TDD sm), and temperature was considered the dominant factor. In 35% of the documented responses, the plant trait responded to warming, but the interannual variation in the trait was not correlated with TDD sm and temperature was considered subordinate to other factors. The abundance of temperature responses that were considered subordinate to other factors suggests that prediction of plant response to temperature that does not account for natural variability may overestimate the importance of temperature and lead to unrealistic projections of the rate of vegetation change due to climate warming.
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The present study examined experimentally the phenological responses of a range of plant species to rises in temperature. We used the climate-change field protocol of the International Tundra Experiment (ITEX), which measures plant responses to warming of 1 to 2°C inside small open-topped chambers. The field study was established on the Bogong High Plains, Australia, in subalpine open heathlands; the most common treeless plant community on the Bogong High Plains. The study included areas burnt by fire in 2003, and therefore considers the interactive effects of warming and fire, which have rarely been studied in high mountain environments. From November 2003 to March 2006, various phenological phases were monitored inside and outside chambers during the snow-free periods. Warming resulted in earlier occurrence of key phenological events in 7 of the 14 species studied. Burning altered phenology in 9 of 10 species studied, with both earlier and later phenological changes depending on the species. There were no common phenological responses to warming or burning among species of the same family, growth form or flowering type (i.e. early or late-flowering species), when all phenological events were examined. The proportion of plants that formed flower buds was influenced by fire in half of the species studied. The findings support previous findings of ITEX and other warming experiments; that is, species respond individualistically to experimental warming. The inter-year variation in phenological response, the idiosyncratic nature of the responses to experimental warming among species, and an inherent resilience to fire, may result in community resilience to short-term climate change. In the first 3 years of experimental warming, phenological responses do not appear to be driving community-level change. Our findings emphasise the value of examining multiple species in climate-change studies.
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Shifts in the phenology of plant and animal species or in the migratory arrival of birds are seen as ‘fingerprints’ of global warming. However, even if such responses have been documented in large continent-wide datasets of the northern hemisphere, all studies to date correlate the phenological pattern of various taxa with gradual climatic trends. Here, we report a previously unobserved phenomenon: severe drought and heavy rain events caused phenological shifts in plants of the same magnitude as one decade of gradual warming. We present data from two vegetation periods in an experimental setting containing the first evidence of shifted phenological response of 10 grassland and heath species to simulated 100-year extreme weather events in Central Europe. Averaged over all species, 32 days of drought significantly advanced the mid-flowering date by 4 days. The flowering length was significantly extended by 4 days. Heavy rainfall (170 mm over 14 days) had no significant effect on the mid-flowering date. However, heavy rainfall reduced the flowering length by several days. Observed shifts were species-specific, (e.g. drought advanced the mid-flowering date for Holcus lanatus by 1.5 days and delayed the mid-flowering date for Calluna vulgaris by 5.7 days, heavy rain advanced mid-flowering date of Lotus corniculatus by 26.6 days and shortened the flowering length of the same species by 36.9 days). Interestingly, the phenological response of individual species was modified by community composition. For example, the mid-flowering date of C. vulgaris was delayed after drought by 9.3 days in communities composed of grasses and dwarf shrubs compared with communities composed of dwarf shrubs only. This indicates that responses to extreme events are context specific. Additionally, the phenological response of experimental communities to extreme weather events can be modified by the functional diversity of a stand. Future studies on phenological response patterns related to climate change would profit from explicitly addressing the role of extreme weather events.
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Background and Aims:  Recent warming has accelerated phenological development of many crops. We quantified the rate of change in date of designated maturity (21.8°Brix), date of harvest, and sugar concentration of berries at harvest in Chardonnay, Cabernet Sauvignon and Shiraz between 1993 and 2006.Methods and Results:  Data from 18 Australian regions indicated that: (i) the date of designated maturity advanced at rates between −0.5 and −3.1 days/year; (ii) trends in the date of designated maturity were unrelated to trends in yield; (iii) trends of monthly temperature ranged from negligible up to 0.19°C/year; (iv) the rate of change in date of designated maturity was correlated with rate of change of temperature for Chardonnay and Cabernet Sauvignon, but not for Shiraz; (v) harvest was accelerated at a rate between −0.4 and −2.4 days/year; (vi) the rate of change in harvest date for Chardonnay was commensurate with the rate of change in maturity, hence berry sugar concentration at harvest remained stable with time; and (vii) the advancement of harvest for Cabernet Sauvignon and Shiraz only partially offset the advancements in maturity, hence the increase in the concentration of berry sugar at harvest, up to ~0.3°Brix/year.Conclusions:  Maturity advanced at rates between half and 3 days per year. On a temperature basis, these rates are comparable to long-term rates reported for the northern hemisphere.Significance of the Study:  This is the first report of time trends in phenology of grapevine in Australia and provides a benchmark for the industry.
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Recent shifts in phenology are the best documented biological response to current anthropogenic climate change, yet remain poorly understood from a functional point of view. Prevailing analyses are phenomenological and approximate, only correlating temperature records to imprecise records of phenological events. To advance our understanding of phenological responses to climate change, we developed, calibrated, and validated process-based models of leaf unfolding for 22 North American tree species. Using daily meteorological data predicted by two scenarios (A2: +3.2 °C and B2: +1 °C) from the HadCM3 GCM, we predicted and compared range-wide shifts of leaf unfolding in the 20th and 21st centuries for each species. Model predictions suggest that climate change will affect leaf phenology in almost all species studied, with an average advancement during the 21st century of 5.0 days in the A2 scenario and 9.2 days in the B2 scenario. Our model also suggests that lack of sufficient chilling temperatures to break bud dormancy will decrease the rate of advancement in leaf unfolding date during the 21st century for many species. Some temperate species may even have years with abnormal budburst due to insufficient chilling. Species fell into two groups based on their sensitivity to climate change: (1) species that consistently had a greater advance in their leaf unfolding date with increasing latitude and (2) species in which the advance in leaf unfolding differed from the center to the northern vs. southern margins of their range. At the interspecific level, we predicted that early-leafing species tended to show a greater advance in leaf unfolding date than late-leafing species; and that species with larger ranges tend to show stronger phenological changes. These predicted changes in phenology have significant implications for the frost susceptibility of species, their interspecific relationships, and their distributional shifts.
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Recent warming of Northern Hemisphere (NH) land is well documented and typically greater in winter/spring than other seasons. Physical environment responses to warming have been reported, but not details of large-area temperate growing season impacts, or consequences for ecosystems and agriculture. To date, hemispheric-scale measurements of biospheric changes have been confined to remote sensing. However, these studies did not provide detailed data needed for many investigations. Here, we show that a suite of modeled and derived measures (produced from daily maximum–minimum temperatures) linking plant development (phenology) with its basic climatic drivers provide a reliable and spatially extensive method for monitoring general impacts of global warming on the start of the growing season. Results are consistent with prior smaller area studies, confirming a nearly universal quicker onset of early spring warmth (spring indices (SI) first leaf date, −1.2 days decade−1), late spring warmth (SI first bloom date, −1.0 days decade−1; last spring day below 5°C, −1.4 days decade−1), and last spring freeze date (−1.5 days decade−1) across most temperate NH land regions over the 1955–2002 period. However, dynamics differ among major continental areas with North American first leaf and last freeze date changes displaying a complex spatial relationship. Europe presents a spatial pattern of change, with western continental areas showing last freeze dates getting earlier faster, some central areas having last freeze and first leaf dates progressing at about the same pace, while in portions of Northern and Eastern Europe first leaf dates are getting earlier faster than last freeze dates. Across East Asia last freeze dates are getting earlier faster than first leaf dates.
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Global climate change impacts can already be tracked in many physical and biological systems; in particular, terrestrial ecosystems provide a consistent picture of observed changes. One of the preferred indicators is phenology, the science of natural recurring events, as their recorded dates provide a high-temporal resolution of ongoing changes. Thus, numerous analyses have demonstrated an earlier onset of spring events for mid and higher latitudes and a lengthening of the growing season. However, published single-site or single-species studies are particularly open to suspicion of being biased towards predominantly reporting climate change-induced impacts. No comprehensive study or meta-analysis has so far examined the possible lack of evidence for changes or shifts at sites where no temperature change is observed. We used an enormous systematic phenological network data set of more than 125 000 observational series of 542 plant and 19 animal species in 21 European countries (1971–2000). Our results showed that 78% of all leafing, flowering and fruiting records advanced (30% significantly) and only 3% were significantly delayed, whereas the signal of leaf colouring/fall is ambiguous. We conclude that previously published results of phenological changes were not biased by reporting or publication predisposition: the average advance of spring/summer was 2.5 days decade−1 in Europe. Our analysis of 254 mean national time series undoubtedly demonstrates that species' phenology is responsive to temperature of the preceding months (mean advance of spring/summer by 2.5 days°C−1, delay of leaf colouring and fall by 1.0 day°C−1). The pattern of observed change in spring efficiently matches measured national warming across 19 European countries (correlation coefficient r=−0.69, P<0.001).
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It has been widely reported that tree leaves have tended to appear earlier in many regions of the northern hemisphere in the last few decades, reflecting climate warming. Satellite observations revealed an 8-day advance in leaf appearance date between 1982 and 1991 in northern latitudes. In situ observations show that leaf appearance dates in Europe have advanced by an average of 6.3 days from 1959 to 1996. Modelling of leaf appearance on the basis of temperature also shows a marked advance in temperate and boreal regions from 1955 to 2002. However, before 1955, reported studies of phenological variations are restricted to local scale. Modelling, ground observations and satellite observations are here combined to analyse phenological variations in Eurasian taiga over nearly a century. The trend observed by remote sensing consists mainly in a shift at the end of the 1980s, reflecting a shift in winter and spring temperature. In western boreal Eurasia, a trend to earlier leaf appearance is evident since the mid-1930s, although it is discontinuous. In contrast, the strong advance in leaf appearance detected over Central Siberia using satellite data in 1982–1991 is strengthened by late springs in 1983–1984; moreover, in this region the green-up timing has displayed successive trends with opposite signs since 1920. Thus, such strong trend is not unusual if considered locally. However, the recent advance is unique in simultaneously affecting most of the Eurasian taiga, the leaf appearance dates after 1990 being the earliest in nearly a century in most of the area.
Article
We used a novel, nonintrusive experimental system to examine plant responses to warming and drought across a climatic and geographical latitudinal gradient of shrubland ecosystems in four sites from northern to southern Europe (UK, Denmark, The Netherlands, and Spain). In the first two years of experimentation reported here, we measured plant cover and biomass by the pinpoint method, plant 14C uptake, stem and shoot growth, flowering, leaf chemical concentration, litterfall, and herbivory damage in the dominant plant species of each site. The two years of approximately 1C experimental warming induced a 15% increase in total aboveground plant biomass growth in the UK site. Both direct and indirect effects of warming, such as longer growth season and increased nutrient availability, are likely to be particularly important in this and the other northern sites which tend to be temperature-limited. In the water-stressed southern site, there was no increase in total aboveground plant biomass growth as expected since warming increases water loss, and temperatures in those ecosystems are already close to the optimum for photosynthesis. The southern site presented instead the most negative response to the drought treatment consisting of a soil moisture reduction at the peak of the growing season ranging from 33% in the Spanish site to 82% in The Netherlands site. In the Spanish site there was a 14% decrease in total aboveground plant biomass growth relative to control. Flowering was decreased by drought (up to 24% in the UK and 40% in Spain). Warming and drought decreased litterfall in The Netherlands site (33% and 37%, respectively) but did not affect it in the Spanish site. The tissue P concentrations generally decreased and the N/P ratio increased with warming and drought except in the UK site, indicating a progressive importance of P limitation as a consequence of warming and drought. The magnitude of the response to warming and drought was thus very sensitive to differences among sites (cold-wet northern sites were more sensitive to warming and the warm-dry southern site was more sensitive to drought), seasons (plant processes were more sensitive to warming during the winter than during the summer), and species. As a result of these multiple plant responses, ecosystem and community level consequences may be expected.
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The Sahel region of Africa has experienced a decrease in rainfall from the early 1960s to mid 1990s. Recent studies have detected an increased in NDVI amplitude and growing season integrated NDVI for the region since 1982. However, these studies have not examined how plant phenology has changed. Phenology examines life cycle events such as bud burst and leaf senescence. Using the software TIMESAT to estimate phenological parameters from the GIMMS AVHRR NDVI dataset, we have found significant positive trends for the length of the growing and end of the growing season for the Soudan and Guinean regions, but significant trends in the Sahel could not be detected. The geographical extent of these trends contrasts with the more northern extent of positive trends of NDVI amplitude and growing season integrated NDVI. Results suggest two types of “greening” trends associated with rainfall change since the drought in the early 1980s.
Article
Abstract New analyses are presented addressing the global impacts of recent climate change on phenology of plant and animal species. A meta-analysis spanning 203 species was conducted on published datasets from the northern hemisphere. Phenological response was examined with respect to two factors: distribution of species across latitudes and taxonomic affiliation or functional grouping of target species. Amphibians had a significantly stronger shift toward earlier breeding than all other taxonomic/functional groups, advancing more than twice as fast as trees, birds and butterflies. In turn, butterfly emergence or migratory arrival showed three times stronger advancement than the first flowering of herbs, perhaps portending increasing asynchrony in insect–plant interactions. Response was significantly stronger at higher latitudes where warming has been stronger, but latitude explained −1 advancement. The scientific community has assumed this difference to be real and has attempted to explain it in terms of biologically relevant phenomena: specifically, differences in distribution of data across latitudes, taxa or time periods. Here, these and other possibilities are explored. All analyses indicate that the difference in estimated response is primarily due to differences between the studies in criteria for incorporating data. It is a clear and automatic consequence of the exclusion by one study of data on ‘stable’ (nonresponsive) species. Once this is accounted for, the two studies support each other, generating similar conclusions despite analyzing substantially nonoverlapping datasets. Analyses here on a new expanded dataset estimate an overall spring advancement across the northern hemisphere of 2.8 days decade−1. This is the first quantitative analysis showing that data-sampling methodologies significantly impact global (synthetic) estimates of magnitude of global warming response.
Article
Following the methodology of K. F. Huemmrich and colleagues [Huemmrich et al. (1999) J Geophys Res 104:27,935-27,944], agrometeorological standard radiation sensors, i.e. two photosynthetically active radiation sensors and an albedometer, were used to measure the broadband visible and optical-infrared reflectance of an oat plot during its whole growth period. From these reflectance data - recorded as 15-min averages and pooled to daily means - the seasonal cycle of the normalised difference vegetation index (NDVI) was calculated. In addition, a ground-based multi-channel spectroradiometer was used as a reference to estimate narrowband "green" and "red" NDVIs at weekly intervals near noon. The narrowband "green" NDVI was shown to be consistent with the simultaneous broadband 15-min NDVI. This shows that the configuration of agrometeorological radiation sensors is suitable to adequately track phenological crop dynamics.
Article
Climatic warming is associated with organisms breeding earlier in the season than is typical for their species. In some species, however, response to warming is more complex than a simple advance in the timing of all life history events preceding reproduction. Disparities in the extent to which different components of the reproductive phenology of organisms vary with climatic warming indicate that not all life history events are equally responsive to environmental variation. Here, we propose that our understanding of phenological response to climate change can be improved by considering entire sequences of events comprising the aggregate life histories of organisms preceding reproduction. We present results of a two-year warming experiment conducted on 33 individuals of three plant species inhabiting a low-arctic site. Analysis of phenological sequences of three key events for each species revealed how the aggregate life histories preceding reproduction responded to warming, and which individual events exerted the greatest influence on aggregate life history variation. For alpine chickweed (Cerastium alpinum), warming elicited a shortening of the duration of the emergence stage by 2.5 days on average, but the aggregate life history did not differ between warmed and ambient plots. For gray willow (Salix glauca), however, all phenological events monitored occurred earlier on warmed than on ambient plots, and warming reduced the aggregate life history of this species by 22 days on average. Similarly, in dwarf birch (Betula nana), warming advanced flower bud set, blooming, and fruit set and reduced the aggregate life history by 27 days on average. Our approach provides important insight into life history responses of many organisms to climate change and other forms of environmental variation. Such insight may be compromised by considering changes in individual phenological events in isolation.
Article
The timing of life history traits is central to lifetime fitness and nowhere is this more evident or well studied as in the phenology of flowering in governing plant reproductive success. Recent changes in the timing of environmental events attributable to climate change, such as the date of snowmelt at high altitudes, which initiates the growing season, have had important repercussions for some common perennial herbaceous wildflower species. The phenology of flowering at the Rocky Mountain Biological Laboratory (Colorado, USA) is strongly influenced by date of snowmelt, which makes this site ideal for examining phenological responses to climate change. Flower buds of Delphinium barbeyi, Erigeron speciosus, and Helianthella quinquenervis are sensitive to frost, and the earlier beginning of the growing season in recent years has exposed them to more frequent mid-June frost kills. From 1992 to 1998, on average 36.1% of Helianthella buds were frosted, but for 1999-2006 the mean is 73.9%; in only one year since 1998 have plants escaped all frost damage. For all three of these perennial species, there is a significant relationship between the date of snowmelt and the abundance of flowering that summer. Greater snowpack results in later snowmelt, later beginning of the growing season, and less frost mortality of buds. Microhabitat differences in snow accumulation, snowmelt patterns, and cold air drainage during frost events can be significant; an elevation difference of only 12 m between two plots resulted in a temperature difference of almost 2 degrees C in 2006 and a difference of 37% in frost damage to buds. The loss of flowers and therefore seeds can reduce recruitment in these plant populations, and affect pollinators, herbivores, and seed predators that previously relied on them. Other plant species in this environment are similarly susceptible to frost damage so the negative effects for recruitment and for consumers dependent on flowers and seeds could be widespread. These findings point out the paradox of increased frost damage in the face of global warming, provide important insights into the adaptive significance of phenology, and have general implications for flowering plants throughout the region and anywhere climate change is having similar impacts.