1,721,032 research outputs found
The plasticity of masting: understanding how and why temporal reproductive patterns vary in trees
Full text linkLong-lived plants like trees often exhibit highly variable, yet synchronised reproduction, commonly referred to as ‘masting’. The boom-and-bust patterns of seed production have complex and far-reaching effects on regeneration and food webs. Understanding how and why masting varies across space and time is crucial, as masting is linked to a spectrum of ecological and environmental challenges, including mitigating climate change-induced tree mortality. Masting plasticity (here used as a synonym of masting variability) signals that regeneration potential might differ between populations, and is related to the stability of food supply for wildlife across species ranges.
Studying the plasticity of masting has historically been complicated by the difficulty of acquiring long-term records across species ranges. This thesis, which examines the plasticity of masting and its drivers, would have been impossible without collating the many observations collected by observers across the world. These data are part of MASTREE+ (Hacket-Pain et al., 2022), the English beech mast survey (Packham et al., 2008), ongoing beech seed sampling efforts across Europe, and my own fieldwork. This thesis also builds on open-access climate (Cornes et al., 2018; Fick & Hijmans, 2017), and species range data (e.g. EUFORGEN, 2022).
I found that intraspecific variation in masting can exceed interspecific variation, and that the commonly held environmental stress hypothesis does not explain how masting varies across space. When examining the temporal variability of masting, I found that climate warming is driving the decline in masting across the species range of European beech (Fagus sylvatica L.). My work reveals that seed collection methods contribute to observed masting plasticity. Not only was seed collection method an important predictor in the spatio-temporal analyses, but the loglinear relationship I found between seed crop estimates of two seed collection methods can lead to different masting metrics.
The insights from this thesis are relevant for a broad spectrum of professionals including biologists, ecologists, foresters, land managers, and public health experts, and inform our understanding of ecosystem dynamics. The findings illustrate the need to acknowledge, incorporate and examine masting plasticity. Masting effects on regeneration and the food web may be more variable than previously assumed. The breakdown of variability in European beech seed production across the species range warns that a covert mechanism is underway which may hinder the regeneration potential of this species under climate change, with great potential to alter forest functioning and community dynamics. Lastly, the effects of sampling methodologies on masting metrics underpin the importance of caution when combining datasets, and the need for calibration. This work also helps to translate between two sampling approaches, and the wider adoption of the highly efficient ground-based timed count may help to expand data sampling efforts and improve our understanding of masting plasticity
Widespread breakdown in masting in European beech due to rising summer temperatures
No full textAbstract Climate change effects on tree reproduction are poorly understood, even though the resilience of populations relies on sufficient regeneration to balance increasing rates of mortality. Forest‐forming tree species often mast, i.e. reproduce through synchronised year‐to‐year variation in seed production, which improves pollination and reduces seed predation. Recent observations in European beech show, however, that current climate change can dampen interannual variation and synchrony of seed production and that this masting breakdown drastically reduces the viability of seed crops. Importantly, it is unclear under which conditions masting breakdown occurs and how widespread breakdown is in this pan‐European species. Here, we analysed 50 long‐term datasets of population‐level seed production, sampled across the distribution of European beech, and identified increasing summer temperatures as the general driver of masting breakdown. Specifically, increases in site‐specific mean maximum temperatures during June and July were observed across most of the species range, while the interannual variability of population‐level seed production (CVp) decreased. The declines in CVp were greatest, where temperatures increased most rapidly. Additionally, the occurrence of crop failures and low seed years has decreased during the last four decades, signalling altered starvation effects of masting on seed predators. Notably, CVp did not vary among sites according to site mean summer temperature. Instead, masting breakdown occurs in response to warming local temperatures (i.e. increasing relative temperatures), such that the risk is not restricted to populations growing in warm average conditions. As lowered CVp can reduce viable seed production despite the overall increase in seed count, our results warn that a covert mechanism is underway that may hinder the regeneration potential of European beech under climate change, with great potential to alter forest functioning and community dynamics.Funder:
Natural Environment Research Council
https://doi.org/10.13039/501100000270Funder:
European Commission
https://doi.org/10.13039/501100000780Funder:
European Research Council
https://doi.org/10.13039/501100000781Funder:
Swiss Federal Institute for Forest, Snow and Landscape Research
https://doi.org/10.13039/501100015742Funder:
European Commission
https://doi.org/10.13039/501100000780Funder:
Austrian Science Fund
https://doi.org/10.13039/501100002428Funder:
Max Planck Institute for Biogeochemistry
https://doi.org/10.13039/501100023519Funder:
Kanton St. Gallen
https://doi.org/10.13039/10003099
Masting
Full text linkAndrew Hacket-Pain introduces the phenomenon known as 'masting', in which perennial plants show extraordinary variation in annual reproductive effort
Climate change and plant reproduction: trends and drivers of mast seeding change
No full textClimate change is reshaping global vegetation through its impacts on plant mortality, but recruitment creates the next generation of plants and will determine the structure and composition of future communities. Recruitment depends on mean seed production, but also on the interannual variability and among-plant synchrony in seed production, the phenomenon known as mast seeding. Thus, predicting the long-term response of global vegetation dynamics to climate change requires understanding the response of masting to changing climate. Recently, data and methods have become available allowing the first assessments of long-term changes in masting. Reviewing the literature, we evaluate evidence for a fingerprint of climate change on mast seeding and discuss the drivers and impacts of these changes. We divide our discussion into the main characteristics of mast seeding: interannual variation, synchrony, temporal autocorrelation, and mast frequency. Data indicate that masting patterns, are changing, but the direction of that change varies, likely reflecting the diversity of proximate factors underlying masting across taxa. Experiments to understand the proximate mechanisms underlying masting, in combination with the analysis of long-term datasets, will enable us to understand this observed variability in the response of masting. This will allow us to predict future shifts in masting patterns, and consequently ecosystem impacts of climate change via its impacts on masting
Climate change and plant reproduction: trends and drivers of mast seeding change
Full text linkClimate change is reshaping global vegetation through its impacts on plant mortality, but recruitment creates the next generation of plants and will determine the structure and composition of future communities. Recruitment depends on mean seed production, but also on the interannual variability and among-plant synchrony in seed production, the phenomenon known as mast seeding. Thus, predicting the long-term response of global vegetation dynamics to climate change requires understanding the response of masting to changing climate. Recently, data and methods have become available allowing the first assessments of long-term changes in masting. Reviewing the literature, we evaluate evidence for a fingerprint of climate change on mast seeding and discuss the drivers and impacts of these changes. We divide our discussion into the main characteristics of mast seeding: interannual variation, synchrony, temporal autocorrelation, and mast frequency. Data indicate that masting patterns, are changing, but the direction of that change varies, likely reflecting the diversity of proximate factors underlying masting across taxa. Experiments to understand the proximate mechanisms underlying masting, in combination with the analysis of long-term datasets, will enable us to understand this observed variability in the response of masting. This will allow us to predict future shifts in masting patterns, and consequently ecosystem impacts of climate change via its impacts on masting.</p
Spatial patterns and broad-scale weather cues of beech mast seeding in Europe.
Full text linkMast seeding is a crucial population process in many tree species, but its spatio-temporal patterns and drivers at the continental scale remain unknown . Using a large dataset (8000 masting observations across Europe for years 1950-2014) we analysed the spatial pattern of masting across the entire geographical range of European beech, how it is influenced by precipitation, temperature and drought, and the temporal and spatial stability of masting-weather correlations. Beech masting exhibited a general distance-dependent synchronicity and a pattern structured in three broad geographical groups consistent with continental climate regimes. Spearman's correlations and logistic regression revealed a general pattern of beech masting correlating negatively with temperature in the summer 2 yr before masting, and positively with summer temperature 1 yr before masting (i.e. 2T model). The temperature difference between the two previous summers (DeltaT model) was also a good predictor. Moving correlation analysis applied to the longest eight chronologies (74-114 yr) revealed stable correlations between temperature and masting, confirming consistency in weather cues across space and time. These results confirm widespread dependency of masting on temperature and lend robustness to the attempts to reconstruct and predict mast years using temperature data
Climate-change-driven growth decline of European beech forests
No full textAbstract The growth of past, present, and future forests was, is and will be affected by climate variability. This multifaceted relationship has been assessed in several regional studies, but spatially resolved, large-scale analyses are largely missing so far. Here we estimate recent changes in growth of 5800 beech trees ( Fagus sylvatica L.) from 324 sites, representing the full geographic and climatic range of species. Future growth trends were predicted considering state-of-the-art climate scenarios. The validated models indicate growth declines across large region of the distribution in recent decades, and project severe future growth declines ranging from −20% to more than −50% by 2090, depending on the region and climate change scenario (i.e. CMIP6 SSP1-2.6 and SSP5-8.5). Forecasted forest productivity losses are most striking towards the southern distribution limit of Fagus sylvatica , in regions where persisting atmospheric high-pressure systems are expected to increase drought severity. The projected 21 st century growth changes across Europe indicate serious ecological and economic consequences that require immediate forest adaptation.Alexander von Humboldt-Stiftun
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Evolution of masting in plants is linked to investment in low tissue mortality
Full text linkAbstractMasting, a variable and synchronized variation in reproductive effort is a prevalent strategy among perennial plants, but the factors leading to interspecific differences in masting remain unclear. Here, we investigate interannual patterns of reproductive investment in 517 species of terrestrial perennial plants, including herbs, graminoids, shrubs, and trees. We place these patterns in the context of the plants’ phylogeny, habitat, form and function. Our findings reveal that masting is widespread across the plant phylogeny. Nonetheless, reversion from masting to regular seed production is also common. While interannual variation in seed production is highest in temperate and boreal zones, our analysis controlling for environment and phylogeny indicates that masting is more frequent in species that invest in tissue longevity. Our modeling exposes masting-trait relationships that would otherwise remain hidden and provides large-scale evidence that the costs of delayed reproduction play a significant role in the evolution of variable reproduction in plants.</jats:p
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