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Masting behaviour of Sitka spruce Picea sitchensis may influence Eurasian siskin Spinus spinus breeding ecology as breeding siskins specialize on spruce seeds. We caught siskins and other small passerines over 16 years using mist nets adjacent to large plantations of mature Sitka spruce. We sexed, aged, measured and weighed the birds and collected feather samples from fledglings to measure nitrogen and carbon stable isotope ratios. Siskins departed in late summer, and returned, and bred earlier in years of higher cone abundance. Nitrogen and carbon isotopes indicated that siskins fed their chicks on Sitka spruce seeds in most years, and more so in years of high cone production. More siskins were caught following heavy rainfall, when the cones had closed, encouraging the birds to seek alternative food sources. Fledglings were not heavier or larger in years with higher cone crops but were more numerous. However, the age ratio of siskins caught the following year was unaffected by cone crop. Given their reliance on Sitka spruce seeds, climate change may have a major impact on siskin numbers by altering the availability of Sitka spruce seeds, either through changes in masting patterns or cone opening, or due to climate-related changes in forestry practices. Siskins represent a valuable study system to conservation ecology, where a native species is ecologically reliant on introduced taxa. [ABSTRACT FROM AUTHOR]

Strobilanthes kunthiana (Nees) T. Anderson ex Benth locally known as Neelakurinji is an endemic to Western Ghat, India and belongs to the Acanthaceae family. It has a unique flowering pattern to bloom every 12 years. The objective of this review is to highlight the taxonomy, distribution, ecology, biology, pharmacological properties, and conservation status of Strobilanthes kunthiana. The plant S. kunthiana is a rich source of pharmacological constituents and can act as herbal alternatives for various disorders. This review discusses the unique botany specifically the flowering pattern for in-depth study to conserve not only for tourism but also for exploring its pharmacological properties and usefulness in apiary. Finally, this review highlights the potential research areas that should be interlinked with promotion of tourism with Neelakurinji attraction as well as its potential use in apiary. [ABSTRACT FROM AUTHOR]

Highlights • We evaluated the impact of climate on meteorological cuing in two masting plants. • Focal species differed in masting habit. • Correlation between weather and seeding is influenced by climate in Quercus petraea. • In Fagus sylvatica cueing is persistent across space. • Responses of plants to weather differ among masting habits. Abstract Many plant species present inter-annual cycles of seed production (mast seeding), with synchronized high seed production across populations in some years. Weather is believed to be centrally involved in triggering masting. The links between meteorological conditions and seeding are well-recognized for some species, but in others consistent correlates have not been found. We used a spatially extensive data set of fruit production to test the hypothesis that the influence of weather on seed production is conditioned by local climate and that this influence varies between species with different life history traits. We used two model species. European beech (Fagus sylvatica) that is a flowering masting species, i.e. seed production is determined by variable flower production, and sessile oak (Quercus petraea) that is a fruit-maturation masting species, i.e. seed production is determined by variable ripening of more constant flower production. We predicted that climate should strongly modulate the relationship between meteorological cue and fruit production in Q. petraea , while the relationship should be uniform in F. sylvatica. The influence of meteorological cue on reproduction in fruiting masting species should be strongly conditioned by local climate because the strength of environmental constraint that modulates the success of flower-to-fruit transition is likely to vary with local climatic conditions. In accordance, the meteorological cuing was consistent in F. sylvatica. In contrast, in Q. petraea the relationship between spring temperature and seed production varied among sites and was stronger in populations at colder sites. The clear difference in meteorological conditioning of seed production between the two studied species suggests the responses of masting plants to weather can be potentially systematized according to their masting habit: i.e. fruiting or flowering. [ABSTRACT FROM AUTHOR]

Highlights • White oak mast failure (≤3.67 ± 8.52 acorns/m2 of crown) occurred 6 of 10 years. • Excellent and good producing trees (39% of trees) produced 69% of all acorns. • Poor producing trees (41% of trees) only produced 17% of all acorns. • Crown-releasing white oaks increased acorn production 47–65%. • Fertilization did not impact acorn production. Abstract Forest management practices that influence mast production in oaks (Quercus spp.) are ecologically and economically important for regeneration of future oak forests, timber products, and wildlife that consume acorns. We conducted a 10-year experiment in upland oak-hickory forests of eastern Tennessee to determine the influence of canopy release, fertilization (addition of nitrogen, phosphorus, and potassium), and their combined influence on white oak (Quercus alba) acorn production, acorn size and quality, and acorn depredation. We used a robust before-after-control-impact design where we collected pre-treatment acorn production (acorns/m2 of crown) data from 120 white oaks for 5 years, applied canopy release and fertilizer treatments and then monitored post-treatment acorn production on the same trees for an additional 5 years. Acorn production was temporally variable with 6 of 10 years being near complete mast failures (≤3.67 ± 8.52 acorns/m2 of crown). Also, production varied greatly among individual trees with 11% of trees classified as excellent producers accounting for 31% of all acorns produced, and 41% of trees classified as poor producers accounting for only 17% of all acorns produced. Canopy-released and canopy-released-and-fertilized trees increased acorn production 65% and 47%, respectively, following treatment relative to control trees, with effects greatest in trees classified as poor producers. Fertilization did not influence acorn production or size and did not consistently influence acorn quality. Furthermore, acorn depredation rates did not differ among treatments. Our results indicate crown release is an important management practice when management objectives include increasing white oak acorn production in closed-canopy conditions, whereas fertilization does not influence acorn production. [ABSTRACT FROM AUTHOR]

Highlights • Pan-European ICP Forests evaluation of weather cues for mast years in five species. • In beech and spruce summer conditions are the main weather cues for mast years. • Spring temperatures in the mast year is the main weather cue for oak species. • Weather cues are consistent on different spatial scales for beech and spruce. • Resource depletion is not present in beech, the oak species, and pine. Abstract Mast seeding, the synchronised occurrence of large amounts of fruits and seeds at irregular intervals, is a reproductive strategy in many wind-pollinated species. Although a series of studies have investigated mast year (MY) patterns in European forest tree species at the regional scale, there are few recent evaluations at a European scale on the impact of weather variables (weather cues) and resource dynamics on mast behaviour. Thus the main objective of this study is to investigate the impact of specific weather conditions, as environmental drivers for MYs, on resources in Fagus sylvatica L., Quercus petraea (Matt.) Liebl. , Quercus robur L., Picea abies (L.) Karst. and Pinus sylvestris L. at a European level and to explore the robustness of the relationships in smaller regions within Europe. Data on seed production originating from the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) were analysed. Three beta regression models were applied to investigate the impact of seasonal weather variables on MY occurrence, as well as the influence of fruiting intensity levels in the years prior to MYs. Resource dynamics are analysed at three different spatial scales (continent, countries and ecoregions). At a European scale, important weather cues for beech MYs were a cold and wet summer two years before a MY, a dry and warm summer one year before a MY and a warm spring in the MY. For spruce, a cold and dry summer two years prior to a MY and a warm and dry summer in the year before the MY showed the strongest associations with the MY. For oak, high spring temperature in the MY was the most important weather cue. For beech and spruce, and to some extent also for oak species, the best fitting models at European scale were well reflected by those found at smaller scales. For pine, best fitting models were highly diverse concerning weather cues. Fruiting levels were high in all species two years before the MY and also high one year before the MY in the oak species and in pine. In beech, fruiting levels one year before the MY were not important and in spruce, they were inconsistent depending on the region. As a consequence, evidence of resource depletion could only be seen in some regions for spruce. [ABSTRACT FROM AUTHOR]

The predator satiation hypothesis posits that masting helps plants escape seed predation through starvation of predators in lean years, followed by satiation of predators in mast years. Importantly, successful satiation requires sufficiently delayed bottom‐up effects of seed availability on seed consumers. However, some seed consumers may be capable of quick aggregative and reproductive responses to masting, which may jeopardize positive density dependence of seed survival. We used a 17‐yr data set on seed production and insect (Curculio weevils) infestation of three North American oaks species (northern red Quercus rubra, white Q. alba, and chestnut oak Q. montana) to test predictions of the predation satiation hypothesis. Furthermore, we tested for the unlagged numerical response of Curculio to acorn production. We found that masting results in a bottom‐up effect on the insect population; both through increased reproductive output and aggregation at seed‐rich trees. Consequently, mast seeding in two out of three studied oaks (white and chestnut oak) did not help to escape insect seed predation, whereas, in the red oak, the escape depended on the synchronization of mast crops within the population. Bottom‐up effects of masting on seed consumer populations are assumed to be delayed, and therefore to have negligible effects on seed survival in mast years. Our research suggests that insect populations may be able to mount rapid reproductive and aggregative responses when seed availability increases, possibly hindering satiation effects of masting. Many insect species are able to quickly benefit from pulsed resources, making mechanisms described here potentially relevant in many other systems. [ABSTRACT FROM AUTHOR]

Abstract: Woody bamboos that undergo masting on a cyclic basis constitute large‐scale endogenous disturbances in forests of America, Africa and Asia, driving long‐ and short‐term effects on community structure and dynamics. Among the transient effects of these nonequilibrial phenomena are rodent outbreaks whose potential bottom‐up consequences on top predators have never been explored. We investigated the effects of unpredictable rodent outbreaks on the assemblage of nocturnal raptors of the southern Andes after a large‐scale (>140 000 ha), spatially heterogeneous, Chusquea culeou masting event in north Argentine Patagonia. We compared owl numbers and behaviours between pre‐masting (2009) and post‐masting (2011) at subsidized (outbreaking rodents) and unsubsidized (normal rodents) contiguous sites. Both generalist (opportunistic forest resident) and rodent‐specialist (forest‐facultative) owls were monitored, with emphasis on the resident territorial rufous‐legged owl (Strix rufipes). The resident owls behaved as predicted, perceiving the rodent increases soon and gathering at subsidized sites, while apparently relaxing territoriality. Contrary to our predictions, later at the rodent outbreak phase, resident territorial owls turned inconspicuous, coinciding – causally or not – with an irruption of forest‐facultative barn owls (Tyto alba tuidara), and influx of some open country short‐eared owls (Asio flammeus suinda, some of which took a chance to breed in the woods). Considering the whole rodent outbreak period, besides significant changes in owls’ numbers, we recorded a notable adjustment in owls’ foraging modes in response to food surplus (consuming prey heads only), and null interference behaviours among all observed species. This study provides a first quantitative assessment of the effects of bamboo episodic masting on top carnivores globally, and contributes novel data on the indirect effects of these events in forests of South America. [ABSTRACT FROM AUTHOR]

Masting is the highly variable and synchronous production of seeds by plants. Masting can have cascading effects on plant population dynamics and forest properties such as tree growth, carbon stocks, regeneration, nutrient cycling, or future species composition. However, masting has often been missing from forest models. Those few that simulate masting have done so using relatively simple empirical rules, and lack an implementation of process-based mechanisms that control such events. Here we review more than 200 published papers on mechanistic formulations of masting, and summarize how the main processes involved in masting and their related patterns can be incorporated in forest models at different degrees of complexity. Our review showed that, of all proximate causes of masting, resource acquisition, storage and allocation were the processes studied most often. Hormonal and genetic regulation of bud formation, floral induction, and anthesis were less frequently addressed. We outline the building blocks of a general process-based model of masting that can be used to improve the oversimplified functions in different types of forest models, and to implement them where missing. A complete implementation of masting in forest models should include functions for resource allocation and depletion, and for pollination, as regulated by both forest structure and weather in the years prior to seed production. When models operate at spatio-temporal scales mismatched with the main masting processes, or if calibration data are not available, simulation can be based on parameterizing masting patterns (variability, synchrony, or frequency). Also, observed masting patterns have the potential to be used as “reality checks” for more process-based forest models wishing to accurately reproduce masting as an emergent phenomenon. [ABSTRACT FROM AUTHOR]

Tree growth is regulated by a combination of exogenous and endogenous factors. Such factors also interact with each other, complicating the understanding of causal links. IN particular, resource allocation is sensitive to reproductive investment, especially in masting species, which in turn is regulated by climatic variables. Both resource allocation and seed production patterns are also sensitive to tree age. This study aims to (1) evaluate the effects of tree age and local and regional climate on tree ring width and seed production by Spanish black pine (Pinus nigra Arn. ssp. salzmannii) forest in Cuenca Mountains (Spain), and (2) assess the relationship between seed production and secondary growth of Spanish black pine. Seed fall was estimated using 60 rectangular seed traps (40 × 50 × 15 cm) from 2000 to 2014, randomly distributed across the study area. Standardized tree-ring chronologies were calculated using a random sample of 106 trees stratified into three age classes (> 80 years; 26-80 years, and ≤ 25 years). Local climate data was obtained from a meteorological station, and regional climate data from the CRU-TS 3.1 dataset. Average seed production ranged over time from 2 to 189 seeds m−2 (coefficient of variation = 157%). We identified four masting years (2000, 2003, 2006, and 2014) using a classification based on percentile seed production. Seed production was regulated by climate of the previous 2-3 years, while tree growth responded to precipitation and temperature in the previous and current year. Independent of climate, high seed production had a negative effect on tree ring width and weakened climate growth relationships, indicating resource depletion. Tree age modulated climate sensitivity, increasing correlations between climate and tree-ring index in older trees. P. nigra has been showed to be a climate sensitive species with a bimodal masting behaviour, which should be taking into account for management purposes and silvicultural guidelines under climate change scenarios. [ABSTRACT FROM AUTHOR]

Aims: Understanding fluctuations in plant reproductive investment can constitute a key challenge in ecology, conservation and management. Masting events of trees (i.e. the intermittent and synchronous production of abundant seeding material) is an extreme example of such fluctuations. Our objective was to establish the degree of spatial and temporal synchrony in common four masting tree species in boreal Finland and account for potential causal drivers of these patterns. Methods: We investigated the spatial intraspecific and temporal interspecific fluctuations in annual seed production of four tree species in Finland, silver birch Betula pendula Roth, downy birch Betula pubescens Ehrh., Norway spruce Picea abies (L.) H.Karst. and rowanberry Sorbus aucuparia L. We also tested to see whether variations in seed production were linked to annual weather conditions. Seeding abundance data were derived from tens of stands per species across large spatial scales within Finland during 1979 to 2014 (for rowanberries only 1986 to 2014). Important Findings: All species showed spatial synchrony in seed production at scales up to 1000 km. Annual estimates of seed production were strongly correlated between species. Spring and summer temperatures explained most variation in crop sizes of tree species with 0-to 2-year time lags, whereas rainfall had relatively little influence. Warm weather during flowering (May temperature) in the flowering year (Year t) and 2 years before (t−2) were correlated with seed production. However, high May temperatures during the previous year (t−1) adversely affected seed production. Summer temperatures in Year t−1 was positively correlated with seed production, likely because this parameter enhances the development of flower primordials, but the effect was negative with a time lag of 2 years. The negative feedback in temperature coefficients is also likely due to patterns of resource allocation, as abundant flowering and seed production in these species is thought to reduce the subsequent initiation of potential new flower buds. Since the most important weather variables also showed spatial correlation up to 1000 km, weather parameters likely explain much of the spatial and temporal synchrony in seed production of these four studied tree species. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms that cause large-scale synchrony in insect population dynamics might yield key insights for predicting potential outbreak occurrence. Here, we evaluated which environmental factors best explain synchronous population fluctuations in the spruce budworm ( Choristoneura fumiferana Clem.) (SBW), a major defoliator of coniferous forests in North America. SBW population levels were assessed with pheromone traps during the 1986-2014 period across a 625 000 km2 territory located in the province of Québec (Canada). The populations were characterized by abundance fluctuations that were often synchronized across the whole study area. Interannual population fluctuations were correlated with host tree cone production (a source of food) and high May temperatures, suggesting that synchrony was influenced by food availability and phenological mismatch during shoot development. Cone production was itself correlated with low precipitation during the previous summer. This study indicates that bottom-up trophic factors can drive spatiotemporal synchrony in insect populations and contribute to explain important and sustained population increases during some years. We also suggest that several biological processes, all influenced by weather, are likely to interact to explain population synchrony during the different phases of the approximately 35 year SBW outbreak cycle, complicating the prediction of climate change effects on this insect. [ABSTRACT FROM AUTHOR]

Seasonal shifts in vegetation-masting events may alter resource availability and influence habitat selection. Crotalus adamanteus (Eastern Damondback Rattlesnake; hereafter, EDB) is an imperiled, ambush predator endemic to southeastern pine savannas and woodlands of the US. Eastern Diamondback Rattlesnakes prey on small mammals that feed on hard and soft mast (e.g., nuts and fruits). In this study, we hypothesized that intra-seasonal shifts in masting vegetation would cause intra-season shifts in ambush-site selection in EDBs as the result of a bottom-up trophic effect. We quantified EDB ambush-site selection using radio-telemetry data and vegetation analysis within a naturalized study site. When we encountered EDBs in ambush posture, we quantified vegetation structure at the selected location and at 2 random locations. We measured understory and overstory structure and masting characteristics within each vegetation plot. Over the June–August study period, we quantified vegetation structure at 35 ambush sites and 70 paired random locations. We used conditional logistic regression to model ambush-site selection. We constructed 5 a priori models to examine ambush-site selection, with soft-mast presence, hard-mast presence, and canopy cover as predictors. The top models supported our hypothesis, indicating a significant association with soft-mast–producing vegetation during times when soft mast was present. Hard-mast presence was also an important predictor of EDB ambush sites. The results of this study indicate that EDB foraging-site selection reflects mast availability, which may be an indication of a bottom-up trophic effect. We should consider mast presence and absence in efforts to manage EDB populations and their prey. [ABSTRACT FROM AUTHOR]

Mast seeding is hypothesized to satiate seed predators with heavy production and reduce populations with crop failure, thereby increasing seed survival. Preference for red or white oak acorns could influence recruitment among oak species. We tested the predator satiation hypothesis, acorn preference, and predator size by concurrently measuring acorn production, mouse abundance, and white versus red oak acorn removal rates in exclosures allowing access by mice (HW), squirrels and smaller-sized vertebrates (WW), or all-sized vertebrates (C) for 12 years. Annual removal rate varied, but virtually all acorns were eventually removed from all exclosure types all years except one. Acorns were removed more slowly from HW than from WW or C exclosures, indicating that large vertebrates were not major acorn consumers, locally. Red and white oak acorn removal rates were similar except in two years, when red oak acorns were removed more rapidly. Removal slowed with increasing acorn crops, suggesting that heavy crops can 'swamp' predators. Removal rate was negatively correlated with crop size the previous fall. A positive trend between mouse abundance and crop size the previous fall was evident; abundance decreased sharply the year following crop failures but not after moderate or heavy crops, suggesting that poor crops can dampen acorn predation the following year. [ABSTRACT FROM AUTHOR]

Climate teleconnections drive highly variable and synchronous seed production (masting) over large scales. Disentangling the effect of high-frequency (inter-annual variation) from low-frequency (decadal trends) components of climate oscillations will improve our understanding of masting as an ecosystem process. Using century-long observations on masting (the MASTREE database) and data on the Northern Atlantic Oscillation (NAO), we show that in the last 60 years both high-frequency summer and spring NAO, and low-frequency winter NAO components are highly correlated to continent-wide masting in European beech and Norway spruce. Relationships are weaker (non-stationary) in the early twentieth century. This finding improves our understanding on how climate variation affects large-scale synchronization of tree masting. Moreover, it supports the connection between proximate and ultimate causes of masting: indeed, large-scale features of atmospheric circulation coherently drive cues and resources for masting, as well as its evolutionary drivers, such as pollination efficiency, abundance of seed dispersers, and natural disturbance regimes. [ABSTRACT FROM AUTHOR]

Mast seeding, or masting, is the highly variable and spatially synchronous production of seeds bya population of plants. The production of variable seed crops is typically correlated with weather, so it is of considerable interest whether global climate change has altered the variability of masting or the size of masting events. We compiled 1086 datasets of plant seed production spanning 1900-2014 and from around the world, and then analysed whether the coefficient of variation (CV) in seed set, a measure of masting, increased over time. Over this 115-year period, seed set became more variable for plants as a whole and for the particularly well-studied taxa of conifers and oaks. The increase in CV corresponded with a decrease in the long-term mean of seed set of plant species. Seed set CV increased to a greater degree in plant taxawith a tendency towards masting. Seed set is becoming more variable among years, especially for plant taxa whose masting events are known to affect animal populations. Such subtle change in reproduction can havewide-rangingeffects on ecosystems because seed crops provide critical resources for a wide range of taxa and have cascading effects throughout food webs. [ABSTRACT FROM AUTHOR]

Spatial clustering is thought to favour the evolution of cooperation because it puts cooperators in a position to help each other. However, clustering also increases competition. The fate of cooperation may depend on how much cooperators cluster relative to defectors, but these clustering differences have not been the focus of previous models and experiments. By competing siderophore-producing cooperator and defector strains of the opportunistic pathogen Pseudomonas aeruginosa in experimental microhabitats, we found that at the spatial scale of individual interactions, cooperator clustering lowers cooperation, but defector clustering favours cooperation. A theoretical model and individual-based simulations show these counterintuitive effects can arisewhen competition and cooperation occur at a single resource-determined scale, with population dynamics cruciallyallowing cooperators and defectors to cluster differently. The results suggest that cooperation relies on the regulation of sufficient defector clustering relative to cooperator clustering, which may be important in bacteria, social amoeba and cancer inhibition. [ABSTRACT FROM AUTHOR]

The article discusses the environmental vetoes, Moran effect and masting that affect the seed production of holm oaks in Mediterranean region. Topics mentioned include the effect of weather conditions on pollen transfer effectiveness of plants or pollination Moran effect, the flowering synchrony of the plant population to determine pollen availability, and the pollen efficiency driven by drought.

Mast seeding, the synchronous intermittent production of large seed crops in populations of perennial plants, is a widespread and widely studied phenomenon. Economy of scale has been demonstrated to provide the ultimate selection factor driving the evolution of masting, for example, in terms of the predator-satiation and pollination-efficiency hypotheses; however, its physiological mechanism is still poorly understood. The resource budget (RB) model assumes that an individual plant requires more resources to flower and fruit than it gains in a year, and therefore only flowers when a specific threshold amount of stored resources is surpassed. Although the RB models have been well explored theoretically, including for resource depletion and pollen coupling, empirical data to support these assumptions are still disputed. Here, we explore the extent to which the RB model applies to masting tree species, focusing on the dynamics of carbon and nitrogen resources in natural temperate forests. There is little empirical evidence that plants use carbohydrates stored over several years to produce fruits; however, nitrogen stores in temperate trees are more commonly depleted after masting. We review the internal nitrogen cycle including resorption during leaf senescence, storage and remobilization, discussing the effect of masting on these processes. Overall, carbohydrates and nitrogen are clearly involved in the proximate mechanisms driving mast seeding, but the determinant resource seems to be species specific. [ABSTRACT FROM AUTHOR]

Masting, the highly variable production of synchronized large seed crops, is a common reproductive strategy in plant populations. In wind-pollinated trees, flowering and pollination dynamics are hypothesized to provide the mechanistic link for the well-known relationship between weather and population-level seed production. Several hypotheses make predictions about the effect of weather on annual pollination success. The pollen coupling hypothesis predicts that weather and plant resources drive the flowering effort of trees, which directly translates into the size of seed crops through efficient pollination. In contrast, the pollination Moran effect hypothesis predicts that weather affects pollination efficiency, leading to occasional bumper crops. Furthermore, the recently formulated phenology synchrony hypothesis predicts that Moran effects can arise because of weather effects on flowering synchrony, which, in turn, drives pollination efficiency. We investigated the relationship between weather, airborne pollen, and seed production in common European trees, two oak species ( Quercus petraea and Q. robur) and beech ( Fagus sylvatica) with a 19-yr data set from three sites in Poland. Our results show that warm summers preceding flowering correlated with high pollen abundance and warm springs resulted in short pollen seasons (i.e., high flowering synchrony) for all three species. Pollen abundance was the best predictor for seed crops in beech, as predicted under pollen coupling. In oaks, short pollen seasons, rather than pollen abundance, correlated with large seed crops, providing support for the pollination Moran effect and phenology synchrony hypotheses. Fundamentally different mechanisms may therefore drive masting in species of the family Fagacae. [ABSTRACT FROM AUTHOR]

Elucidating the physiological mechanisms of the irregular yet concerted flowering rhythm of mass flowering tree species in the tropics requires long-term monitoring of flowering phenology, exogenous and endogenous environmental factors, as well as identifying interactions and dependencies among these factors. To investigate the proximate factors for floral initiation of mast seeding trees in the tropics, we monitored the expression dynamics of two key flowering genes, meteorological conditions and endogenous resources over two flowering events of Shorea curtisii and Shorea leprosula in the Malay Peninsula. Comparisons of expression dynamics of genes studied indicated functional conservation of FLOWERING LOCUS T ( FT) and LEAFY ( LFY) in Shorea. The genes were highly expressed at least 1 month before anthesis for both species. A mathematical model considering the synergistic effect of cool temperature and drought on activation of the flowering gene was successful in predicting the observed gene expression patterns. Requirement of both cool temperature and drought for floral transition suggested by the model implies that flowering phenologies of these species are sensitive to climate change. Our molecular phenology approach in the tropics sheds light on the conserved role of flowering genes in plants inhabiting different climate zones and can be widely applied to dissect the flowering processes in other plant species. [ABSTRACT FROM AUTHOR]

Mast seeding is characteristic of many long-lived tree species and widely proposed as a mechanism to reduce seed predation. However, whether the efficiency of this reproductive response may vary depending on type of seed predator (e.g., invertebrates vs. vertebrates) or depending on local characteristics, remains seldom explored. We evaluated for 8 yrs the patterns of seed production in antarctic beech ( Nothofagus antarctica ) forests related to management and its influence on insect and bird pre-dispersal seed predation. Along the study, mature seed production was highly variable across years (the population-level coefficient of variation, CVp: 0.98–1.14) and spatially synchronized (Pearson correlation coefficient: 0.83–0.86). Forest type (primary unmanaged, secondary-growth and managed stands) did not influence the amount of seed production nor masting patterns. Mean yearly seed predation by insects was higher than by birds, and their relationship with seeding patterns differed: i.e., while the proportion of seeds predated by insects increased during non-mast years maximum bird predation occurred in mast years. Therefore, predation by insects and birds showed a strong negative relationship. Our results suggest that effectiveness of masting to escape seed predators may be highly depend on the type of predator. We address whether this effect may be due to differences in life history traits among the seed predators involved (i.e., degree of host specificity, dispersal ability or the duration of the life-cycle) and whether an “imperfect” control of avian seed predation may partially be advantageous for the dynamics of the masting species to enhance seed dispersal. [ABSTRACT FROM AUTHOR]

A simultaneous masting of two abundant species in the temperate forests of North-West Argentinean Patagonia occurred in 2013 for the first time ever recorded: the semelparous bamboo grass Chusquea culeou (colihue), dominating the understory, flowered and set seed across 1100 km2 while pehuén ( Araucaria araucana), an endemic conifer co-dominating the tree layer had the highest regionally synchronized mast event in the last 30 years. Strong trophic effects were expected as a consequence of this extraordinary amount of seed, such as rodent outbreaks ( ratadas) that followed previous Chusquea spp. mast events and included Oligoryzomys longicaudatus, the main reservoir of the Andes virus causing the Hantavirus Pulmonar Syndrome. From March 2013 to May 2014, we sampled relative abundance and activity of seed-eaters and carnivores at four study sites with different proportions of both masting species. Surprisingly, total rodent capture rates never exceeded 14% in wild habitats and 8% in peridomestic areas showing low overall density in spite of some heavy O. longicaudatus males extending their reproductive activity into winter. Total abundance and relative proportion of granivorous birds peaked at the four sites in winter or spring, when they are usually scarce. Other surveyed organisms (native and exotic seed-eaters, ungulates and carnivores) showed moderate responses at most, probably through aggregation from surrounding areas rather than reproduction. Seed removal from experimental seed stations varied in time and space though never peaked. The clearest pattern of community responses, though much subtler than expected, occurred at the site where colihue was abundant and pehuén scarce. This is the first systematic study that reports such a simultaneous double masting and our surveys revealed no widespread community consequences. We propose that either contingent events, such as an unprecedented drought, or permanent environmental features or contextual characteristics may explain the lack of a rodent outbreak in this area. [ABSTRACT FROM AUTHOR]

Masting is defined as the intermittent highly variable production of seed in a plant population. According to reproductive modes, that is, sexual and asexual reproduction, masting species can be separated into three groups, that is, (1) species, for example, bamboo, flower only once before they die; (2) species, for example, Fagus, reproduce sexually; and (3) species, for example, Stipa tenacissima, reproduce both sexually and asexually. Several theories have been proposed to explore the underlying mechanisms of masting. However, to our knowledge, no theory has been found to explain the mechanism of masting species that reproduce both sexually and asexually. Here we refine the Resource Budget Model by considering a trade-off between sexual and asexual reproduction. Besides the depletion efficient (i.e., the ratio of the cost of seed setting and the cost of flowering), other factors, such as the annual remaining resource (i.e., the rest of the resource from the photosynthetic activity after allocating to growth and maintenance), the trade-off between sexual and asexual reproduction, and the reproductive thresholds, also affect masting. Moreover, two potential reproductive strategies are found to explain the mechanisms: (1) When the annual remaining resource is relatively low, plants reproduce asexually and a part of the resource is accumulated as the cost of asexual reproduction is less than the annual remaining resource. Plants flower and set fruits once the accumulated resource exceeds the threshold of sexual reproduction; (2) when the annual remaining resource is relatively high, and the accumulated resource surpasses the threshold of sexual reproduction, masting occurs. Remarkably, under certain depletion efficient, more investigation in sexual reproduction will lead plants to reproduce periodically. Additionally, plants investigate less resource to reproduce periodically when depletion efficient keeps increasing as plants can reproduce efficiently. Overall, our study provides new insights into the interpretation of masting, especially for species that reproduce both sexually and asexually. [ABSTRACT FROM AUTHOR]

Mast 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. [ABSTRACT FROM AUTHOR]

In Southeast Asian tropical rainforests, community-level masting (CM) occurs at irregular intervals of 2-10 years. During CM periods, many plant species from various families synchronously flower and subsequently undergo community-level fruiting. Seed predation is a key factor in understanding the ecological and evolutionary factors affecting CM. Masting is proposed to decrease seed mortality due to predation in two ways: by depressing predator abundance through extended and unpredictable absences of seeds; and by satiating predators via mass seed production (predator satiation hypothesis). If the hypothesis is valid in these rainforests, the incidence of seed predation will be higher in a fruiting event that occurs soon after a previous fruiting event, because the intervening period of seed absence would be inadequate to starve the predators. In this study, we examined seed predation by insects, focusing on five dipterocarp species that exceptionally reproduced twice during an extended CM period. All of the five species suffered more intense seed predation in the second fruiting event, consistent with the prediction expected from the predator satiation hypothesis. Weevils, bark beetles and mammals were the main cause of increased seed predation in three, one and one plant species, respectively. However, seed predation intensity did not increase during the second fruiting event in a few combinations of predator and plant species. We discuss the possibility that competition for seeds among predators and/or the interspecific differences in life history traits among predators might affect the varying intensities of seed predation among dipterocarp species by different seed predators. [ABSTRACT FROM AUTHOR]

Trees commonly reproduce via masting cycles, which involves synchronized inter-annual variability in fruit crop size. A few individuals in a population will commonly produce much more fruit than others. If these trees produce fruit more frequently, as indicated by a lower inter-annual variability in fruit production, they may dominate fruit production over time., By measuring fruit production of 1635 individuals of 10 temperate tree species across 4 years in northern lower Michigan, we estimated the inter-annual variability and synchrony in each species. We compared fruit production estimates with measurements of tree size, soil nutrient availability and neighbourhood crowding to investigate the source of inter-individual variation in number of fruit produced., We found that trees' fruit production increased with tree size. The trees that accounted for the largest proportion of total fruit production had lower inter-annual variability and higher synchrony in fruit production. These 'super-producer' trees tended to have high nutrient availability and few neighbouring trees, but there were no effects of nutrient availability or neighbourhood crowding on fruit production in the population as a whole., Synthesis. Masting is a population-level phenomenon, and is typically studied at this level. However, when we apply individual tree observations of fruit production to this phenomenon, it reveals super-producers which produce fruit more consistently than the rest of the population. By reducing inter-annual variability in fruit production, but increasing synchrony and making large numbers of fruit, super-producers may be able to reap the benefits of masting while governing population fruit production over time. [ABSTRACT FROM AUTHOR]

We examined whether particular years of mast seed production in sugar maple ( Acer saccharum) are associated with increased likelihood of cohort recruitment success into the sapling stage over three decades of heavy browsing pressure from white-tailed deer in a mature woodland population in southeastern Ontario, Canada. The population was sampled in 2014 for seedling and sapling stages (≤6 cm in stem diameter) to obtain an age frequency distribution spanning about 80 y and including survivors of seed cohorts produced in two known mast years at the study site (2013 and 1984) and in other mast years known to have occurred within the broader region (but not confirmed for the study site). The age frequency distribution is roughly bimodal with zero to very few individuals recorded for ages 9 through 29 y, corresponding with the known time period (early 1980's to late 2000's) of regional overabundance for white-tailed deer in eastern Ontario and at the study site in particular. The 1 y old seedlings (from the 2013 mast year) and the survivors of putative mast year cohorts from 2006 and 2000, however, are especially conspicuous, with less striking recruitment success indicated for the older confirmed mast year cohort from 1984 (which had more years of accumulated impact from mortality risks). Our results suggest seed masting in sugar maple can bolster cohort recruitment success that otherwise would virtually (or completely) fail when severe impact from deer browsing is combined with other typical early life-stage mortality risks, e.g., from drought, neighborhood competition, and persistent overhead canopy shade. [ABSTRACT FROM AUTHOR]

Mast seeding is the synchronous production of large seed crops in plant populations and for many tree species is known to be determined by the interaction between weather cues and internal plant resources. We use a 24-year record of seedfall for sugar maple ( Acer saccharum Marsh.) and American beech ( Fagus grandifolia Ehrh.) across a northern hardwood forest landscape to quantify their masting patterns and explore the relationship between mast years, resources, and weather cues, particularly the difference between summer temperatures in the two years prior to the seedfall year (Δ T). We found clear evidence of masting in these species, and mast years were often coincident in the two species; masting was best predicted by Δ T or Δ T plus previous-year seedfall. We saw no evidence for correspondence of masting in these trees to precipitation cues. A soil calcium addition modified elevation effects on seed production. Clarification of the controls on mast seeding for these important tree species will aid in predicting such resources as mast for wildlife and maple sugar production in northern hardwood forests. [ABSTRACT FROM AUTHOR]

Escaping seed predation is a classic "economy of scale" hypotheses (predator satiation hypothesis, Psh) to explain the selection for the synchronous production of massive and nil seed crops (masting) in plants. The Psh postulates that predator satiation occurs through a combination of (1) "functional satiation," as not all seeds can be consumed during a massive crop and (2) "numerical satiation," as predator populations collapse during poor crop years. Many studies advocate for the Psh, but few have investigated the importance of masting compared to other factors for the control of predation extent. Namely, environmental cues prompting masting could also determine predator's success and, ultimately, influence directly and independently seed predation intensity. We explored this question in Mediterranean oaks, as they exhibit strong masting behavior; acorns are heavily predated upon by weevils; and rainfall stochasticity drives masting and the emergence of adult weevils from the soil. Results of two mid-term studies (4 and 11 yr) showed that acorn production and predation were highly variable across years, while the abundance of adult weevils was positively related to autumn rainfall and to the number of infested acorns the previous years. Ultimately, acorn predation was negatively influenced by inter-annual fluctuation of seed production (masting) yet, mainly and positively, prompted by autumn rainfall and acorn crop size (only in one site). Our results highlight the relevance of masting to reduce seed predation. Yet evidences that rainfall stochasticity directly determines the success of weevils and it independently influences seed predation extent, indicate that environmental cues prompting masting may also fine-tune the output of this reproductive behavior. Additionally, local differences suggest that the relevance of masting may change with tree characteristics (low vs. high seed production) and landscape structure (isolated vs. dense forests). We also discuss what can be the effects of increasing drought in Mediterranean areas for this antagonistic interaction, triggered by rainfall. [ABSTRACT FROM AUTHOR]

'Bottom-up' influences, that is, masting, plus population density and climate, commonly influence woodland rodent demography. However, 'top-down' influences (predation) also intervene. Here, we assess the impacts of masting, climate, and density on rodent populations placed in the context of what is known about 'top-down' influences. To explain between-year variations in bank vole Myodes glareolus and wood mouse Apodemus sylvaticus population demography, we applied a state-space model to 33 years of catch-mark-release live-trapping, winter temperature, and precise mast-collection data. Experimental mast additions aided interpretation. Rodent numbers in European ash Fraxinus excelsior woodland were estimated (May/June, November/December). December-March mean minimum daily temperature represented winter severity. Total marked adult mice/voles (and juveniles in May/June) provided density indices validated against a model-generated population estimate; this allowed estimation of the structure of a time-series model and the demographic impacts of the climatic/biological variables. During two winters of insignificant fruit-fall, 6.79 g/m2 sterilized ash seed (as fruit) was distributed over an equivalent woodland similarly live-trapped. September-March fruit-fall strongly increased bank vole spring reproductive rate and winter and summer population growth rates; colder winters weakly reduced winter population growth. September-March fruit-fall and warmer winters marginally increased wood mouse spring reproductive rate and September-December fruit-fall weakly elevated summer population growth. Density dependence significantly reduced both species' population growth. Fruit-fall impacts on demography still appeared after a year. Experimental ash fruit addition confirmed its positive influence on bank vole winter population growth with probable moderation by colder temperatures. The models show the strong impact of masting as a 'bottom-up' influence on rodent demography, emphasizing independent masting and weather influences; delayed effects of masting; and the importance of density dependence and its interaction with masting. We conclude that these rodents show strong 'bottom-up' and density-dependent influences on demography moderated by winter temperature. 'Top-down' influences appear weak and need further investigation. [ABSTRACT FROM AUTHOR]

Questions Mast seeding, i.e. synchronous highly variable seed production among years, occurs in many perennial plant species and across diverse plant communities. Two predominant hypotheses for mast seeding are pollination efficiency and predator satiation, with weather conditions as a proximate cause. Little consensus has been achieved regarding the relative impacts of ultimate selection and proximate weather on variation in seed production. Moreover, mast-seeding studies often focus on a single species or phylogenetically closely related species, while studies on plant communities consisting of tree species with a diversity of reproductive strategies are less common. Location A 25-ha Changbaishan temperate forest dynamic plot, northeast China. Methods We used 8 yr of seed rain data to characterize patterns and evaluate underlying selective drivers of mast seeding. We employed generalized linear mixed-effects models (GLMMs) to analyse the relationships between inter-annual variability of mast seeding and weather conditions. Results All 20 species in this forest community exhibited high variability in annual seed production, but the magnitude of seed production among species was generally asynchronous across years. Wind-pollinated species had higher inter-annual variation of seed production than animal-pollinated species, while species dispersed by seed predators and abiotic modes (e.g. wind and gravity) showed little variation. Species responded individually to weather conditions for both temperature and precipitation, and spring phenology in the same year as seed production had a larger effect among species than both the weather conditions of the same summer and season-long lags. Conclusions Our findings suggest that pollination efficiency hypothesis had a much stronger effect than predation satiation hypothesis on mast seeding, and weather conditions demonstrated the proximate role of weather drivers in producing the community-wide mast-seeding pattern. We emphasize the need to simultaneously assess drivers of mast seeding for multiple species within a plant community. [ABSTRACT FROM AUTHOR]

Furcraea parmentieri (Roezl ex Ortgies) García-Mend. is a long-lived, semelparous threatened species with a restricted geographic distribution. We studied the demography of this species in southwest of Mexico City using periodic matrices. We followed the fate of 404 individuals (in 2006-2007) and performed seed germination and seedling establishment experiments in the field (in 2007-2008) to estimate survival, growth and reproduction probabilities of individuals in eight size categories, according to plant height. Population structure was characterized by a high number of saplings, as well as medium and large plants. We built three annual matrices that described the demography in different phases of the population cycle: regular years (RG) characterized by low fecundity and low adult mortality; mast-seeding years (MS) with low seedling emergence and high adult mortality (related to semelparity); and post mast-seeding years (PS) with a high emergence of seedlings and bulbils. Periodic matrices were built simulating three scenarios, which consisted of mast-seeding events occurring every 5, 10, or 15 years. Finite population growth rates ( λ) were 1.03 (RG year), 0.99 (MS year), and 1.25 (PS year). The long term population growth rate values projected over a 90 year period (estimated on an annual basis) were higher as the frequency of mast-seeding events increased. We estimated that individuals reproduce at an age of 60-90 years and that most new recruits originate via sexual reproduction. Although the population has a potential for growth, its persistence may be threatened due to land use change. [ABSTRACT FROM AUTHOR]

Home range size generally decreases with increasing population density, but testing how this relationship is influenced by other factors (e.g., food availability, kin structure) is a difficult task. We used spatially explicit capture-recapture models to examine how home range size varies with population density in the yellow-necked mouse ( Apodemus flavicollis). The relationship between population density and home range size was studied at two distinct phases of population fluctuations induced by beech ( Fagus sylvatica) masting: post-mast peak in abundance (first summer after mast, n = 2) and subsequent crash (second summer after mast, n = 2). We live-trapped mice from June to September to avoid the confounding effects of autumn seedfall on home range size. In accordance with general predictions, we found that home range size was negatively associated with population density. However, after controlling for the effect of density, home ranges of mice were larger in post-mast years than during the crash phase. This indicates a higher spatial overlap among neighbors in post-mast years. We suggest that the increased spatial overlap is caused by negative density-dependent dispersal that leads to high relatedness of individuals within population in the peak phase of the cycle. [ABSTRACT FROM AUTHOR]

Longleaf pine ( Pinus palustris) regeneration is dependent on above-average masting (i.e., cone crop) years that occur over 5- to 7-yr cycles. Not understood, however, is how annual cone mast influences radial growth for longleaf pine. Here, we collected tree-ring data from one site in South Carolina and two sites in North Carolina to examine: (a) the relationship between longleaf pine mast and radial growth; (b) how timber thinning at one site affected this relationship; and (c) how previous October to current April Palmer drought severity index (PDSI) affects mast. We used dendroecological techniques to assemble three radial growth chronologies and compared annual radial growth to annual mast. We found the strongest negative correlation when mast was lagged 1 year from radial growth (i.e., mast of Year X with radial growth of Year X − 1), but current-year mast and growth were not significantly correlated. Mast/radial growth relationships were only detectible when radial growth indices less than 0.95, suggesting that trees reallocated resources from radial growth to mast production. Thinning improved annual mast yield, yet neutralized the negative relationship between mast and radial growth. Mast correlated with PDSI in the unthinned site, but not in the thinned site, suggesting that stand dynamics in the thinned site may have overridden climate/mast relationships. These findings reveal the utility of detecting endogenous factors in radial growth for longleaf pine and the benefits of reducing stand density for improving mast. [ABSTRACT FROM AUTHOR]

Context-dependency in species interactions is widespread and can produce concomitant patterns of context-dependent selection. Masting (synchronous production of large seed crops at irregular intervals by a plant population) has been shown to reduce seed predation through satiation (reduction in rates of seed predation with increasing seed cone output) and thus represents an important source of context-dependency in plant-animal interactions. However, the evolutionary consequences of such dynamics are not well understood., Here we describe masting behaviour in a Mediterranean model pine species ( Pinus pinaster) and present a test of the effects of masting on selection by seed predators on reproductive output. We predicted that masting, by enhancing seed predator satiation, could in turn strengthen positive selection by seed predators for larger cone output. For this we collected six-year data (spanning one mast year and five non-mast years) on seed cone production and seed cone predation rates in a forest genetic trial composed by 116 P. pinaster genotypes., Following our prediction, we found stronger seed predator satiation during the masting year, which in turn led to stronger seed predator selection for increased cone production relative to non-masting years., These findings provide evidence that masting can alter the evolutionary outcome of plant-seed predator interactions. More broadly, our findings highlight that changes in consumer responses to resource abundance represent a widespread mechanism for predicting and understanding context dependency in plant-consumer evolutionary dynamics. [ABSTRACT FROM AUTHOR]

The contribution of new photo-assimilates and stored carbon (C) to plant growth remains poorly understood, especially during reproduction. In order to elucidate how mast seeding affects C allocation to both reproductive and vegetative tissues, we measured biomass increase in each tissue, branch starch concentration and stable C isotope composition (δ13C) in bulk leaves, current-year shoots, 3-year branches and tree rings in fruiting and non-fruiting trees for 2 years, as well as in fruits. We isolated the effect of reproduction on C allocation to vegetative growth by comparing 13C enrichment in woody tissues in fruiting and nonfruiting specimens. Compared with 2‰ 13C enrichment in shoots relative to leaves from non-fruiting trees, fruiting reduced the enrichment to 1‰ and this reduction disappeared in the following year with no fruiting, indicating that new photo-assimilates are preferentially used for woody tissues even with fruiting burden. In contrast, fruits had up to 2.5‰ 13C enrichment at midsummer, which dropped thereafter, indicating that fruit production relies on C storage early in the growing season then shifts to current photo-assimilates. At this tipping point, growth of shoots and cupules had almost finished and nuts had a second rapid growth period thereafter. Together with shorter shoots but higher biomass increment per length in fruiting trees than nonfruiting trees, these results indicate that the C limitation due to fruit burden is minimized by fine-tuning of allocation of old C stores and new photo-assimilates, along with the growth pattern in various tissues. Furthermore, fruiting had no significant effect on starch concentration in 3-year-old branches, which became fully depleted during leaf and flower flushing but were quickly replenished. These results indicate that reproduction affects C allocation to branches but not its source or storage. These reproduction-related variations in the fate of C have implications for evaluating forest ecosystem C cycles during climate change. [ABSTRACT FROM AUTHOR]

Mast seeding is a widespread and widely studied phenomenon. However, the physiological mechanisms that mediate masting events and link them to weather and plant resources are still debated. Here, we explore how masting is affected by plant resource budgets, fruit maturation success, and hormonal coordination of cues including weather and resources. There is little empirical support for the commonly stated hypothesis that plants store carbohydrates over several years to expend in a high-seed year. Plants can switch carbohydrates away from growth in high-seed years, and seed crops are more probably limited by nitrogen or phosphorus. Resources are clearly involved in the proximate mechanisms driving masting, but resource budget (RB) models cannot create masting in the absence of selection because some underlying selective benefit is required to set the level of a 'full’ seed crop at greater than the annual resource increment. Economies of scale (EOSs) provide the ultimate factor selecting for masting, but EOSs probably always interact with resources, which modify the relationship between weather cues and reproduction. Thus, RB and EOS models are not alternative explanations for masting - both are required. Experiments manipulating processes that affect mast seeding will help clarify the physiological mechanisms that underlie mast seeding. [ABSTRACT FROM AUTHOR]

Although the functional basis of variable and synchronous seed production (masting behavior) has been extensively investigated, only recently has attention been focused on the proximate mechanisms driving this phenomenon. We analyzed the relationship between weather and acorn production in 15 species of oaks (genus Quercus) from three geographic regions on two continents, with the goals of determining the extent to which similar sets of weather factors affect masting behavior across species and to explore the ecological basis for the similarities detected. Lag-1 temporal autocorrelations were predominantly negative, supporting the hypothesis that stored resources play a role in masting behavior across this genus, and we were able to determine environmental variables correlating with acorn production in all but one of the species. Standard weather variables outperformed 'differential-cue' variables based on the difference between successive years in a majority of species, which is consistent with the hypothesis that weather is linked directly to the proximate mechanism driving seed production and that masting in these species is likely to be sensitive to climate change. Based on the correlations between weather variables and acorn production, cluster analysis failed to generate any obvious groups of species corresponding to phylogeny or life-history. Discriminant function analyses, however, were able to identify the phylogenetic section to which the species belonged and, controlling for phylogeny, the length of time species required to mature acorns, whether they were evergreen or deciduous, and, to a lesser extent, the geographic region to which they are endemic. These results indicate that similar proximate mechanisms are driving acorn production in these species of oaks, that the environmental factors driving seed production in oaks are to some extent phylogenetically conserved, and that the shared mechanisms driving acorn production result in some degree of synchrony among coexisting species in a way that potentially enhances predator satiation, at least when they have acorns requiring the same length of time to mature. [ABSTRACT FROM AUTHOR]

Synchronised and fluctuating reproduction by plant populations, called masting, is widespread in diverse taxonomic groups. Here, we propose a new method to explore the proximate mechanism of masting by combining spatiotemporal flowering data, biochemical analysis of resource allocation and mathematical modelling. Flowering data of 170 trees over 13 years showed the emergence of clustering with trees in a given cluster mutually synchronised in reproduction, which was successfully explained by resource budget models. Analysis of resources invested in the development of reproductive organs showed that parametric values used in the model are significantly different between nitrogen and carbon. Using a fully parameterised model, we showed that the observed flowering pattern is explained only when the interplay between nitrogen dynamics and climatic cues was considered. This result indicates that our approach successfully identified resource type-specific roles on masting and that the method is suitable for a wide range of plant species. [ABSTRACT FROM AUTHOR]

Wood mouse ( Apodemus sylvaticus) populations are expected to show a peak in autumn in the year after a mast year of sessile oak ( Quercus petraea), because stored acorns increase winter survival. In Aust-Agder, South Norway, only 16 of 34 mast years from 1939-2014 were followed by a year with a peak in the wood mouse population. For many of the remaining instances, there rather was a minor peak 2 or 3 years after the mast. In multiple logistic regression models, the probability of a wood mouse population peak after a mast year of sessile oak was positively related to a snow-corrected temperature index of the previous winter and negatively to a small rodent population index of the previous autumn. The present study thus supports the hypothesis that longer periods with snow-free ground and subzero temperatures negatively affect wood mouse winter survival. Because it may be difficult for wood mice to survive on a diet consisting of acorns alone, the negative relationship with the rodent population index of the previous year is most likely caused by an over-exploitation of necessary alternative food resources, such as other plant seeds and arthropods. Stored acorns not utilized during one winter are assumed to benefit wood mice in a succeeding winter, giving a delayed population peak relative to the mast year. [ABSTRACT FROM AUTHOR]

Temporal patterns of masting in conifer species are intriguing phenomena that have cascading effects on different trophic levels in ecosystems. Many studies suggest that meteorological cues (changes in temperature and precipitation) affect variation in seed-crop size over years. We monitored cone crops of six conifer species in the Italian Alps (1999-2013) and analysed which seasonal weather factors affected annual variation in cone production at forest community level. Larch, Norway spruce and silver fir showed masting while temporal patterns in Pinus sp. were less pronounced. We found limited support for the temperature difference model proposed by Kelly et al. Both seasonal (mainly spring and summer) temperatures and precipitations of 1 and 2 years prior to seed maturation affected cone-crop size, with no significant effect of previous year's cone crop. Next, we estimated future forest cone production until 2100, applying climate projection (using RCP 8.5 scenario) to the weather model that best predicted variation in measured cone crops. We found no evidence of long-term changes in average cone production over the twenty-first century, despite increase in average temperature and decrease in precipitation. The amplitude of predicted annual fluctuations in cone production varies over time, depending on study area. The opposite signs of temperature effects 1 and 2 years prior to seed set show that temperature differences are indeed a relevant cue. Hence, predicted patterns of masting followed by 1 or more years of poor-medium cone production suggest a high degree of resilience of alpine conifer forests under global warming scenario. [ABSTRACT FROM AUTHOR]

Pinus pinea is one of the most important tree species in the Mediterranean region due to the economic value of its edible seeds called 'piñones'. Timber also represents an important source of income from this species. Generally, P. pinea stands have been managed to maximize either timber or seed production, optimization of the joint production of both products being rare. The difficulty in optimizing seed or joint production is the highly stochastic masting habit of P. pinea. The aim of the present study was to find the optimal management of P. pinea stands from the economic point of view when both seed and timber production are considered. A growth and yield model was employed to simulate the dynamics of P. pinea stands of the northern Iberian Peninsula. The novelty of the study is the implementation of a cone yield model that is able to predict expected cone harvests and seed yields when masting is stochastic. The model was linked with an optimization algorithm to obtain optimal schedules for two different stands. The results showed that seed production of P. pinea in the northern plateau of the Iberian Peninsula may increase the soil expectation value by more than 300 % in dense stands and 200 % in sparse stands. When seed yields were considered, rotation lengths were longer and thinnings were delayed. The results were highly sensitive to cone prices and discount rates. [ABSTRACT FROM AUTHOR]

PREMISE OF THE STUDY: The distribution of Yucca brevifolia, a keystone species of the Mojave Desert, may contract with climate change, yet reproduction and dispersal are poorly understood. We tracked reproduction, seed predation, and fruit dispersal for two years and discuss whether Y. brevifolia is a masting species. METHODS: Fruit maturation, seed predation (larval yucca moths), and fruit dispersal (rodents) were monitored on a random sample of panicles during 2013 and 2014, which were years of high and low reproduction, respectively. Fates of fruits placed on the ground and in canopies were also tracked. Rodents were live-trapped to assess abundance and species composition. KEY RESULTS: In 2013,66% of inflorescences produced fruit of which 53% escaped larval predation; 19.5% of seeds were destroyed in infested fruits. Total seed production was estimated to be >100 times greater in 2013 than 2014. One-third of the fruit crop fell to the ground and was removed by rodents over the course of 120 d. After ground fruits became scarce, rodents exploited canopy fruits. Rodent numbers were low in 2013, so fruits remained in canopies for 370 d. In 2014, fruit production was approximately 20% lower. Larvae infested the majority of fruits, and almost twice the number of seeds were damaged. Fruits were exploited by rodents within 65 d. CONCLUSIONS: High fertilization, prolific seed production, and low predispersal predation in 2013 suggests that pollinator attraction and satiation of seed predators influence masting in Y. brevifolia. Abundant, prolonged fruit availability to seed-dispersing rodents likely extends recruitment opportunities during mast years. [ABSTRACT FROM AUTHOR]

Although negative density dependence (NDD) can facilitate tree species coexistence in forests, the underlying mechanisms can differ, and rarely are the dynamics of seedlings and saplings studied together. Herein we present and discuss a novel mechanism based on our investigation of NDD predictions for the large, grove-forming ectomycorrhizal mast fruiting tree, Microberlinia bisulcata (Caesalpiniaceae), in an 82.5-ha plot at Korup, Cameroon. We tested whether juvenile density, size, growth and survival decreases with increasing conspecific adult basal area for 3245 'new' seedlings and 540 'old' seedlings (< 75-cm tall) during an approximately 4-year study period (2008-2012) and for 234 'saplings' (≥ 75-cm tall) during an approximately 6-year study period (2008-2014). We found that the respective densities of new seedlings, old seedlings and saplings were positively, not and negatively related to increasing BA. Maximum leaf numbers and heights of old seedlings were negatively correlated with increasing basal areas, as were sapling heights and stem diameters. Whereas survivorship of new seedlings decreased by more than one-half with increasing basal area over its range in 2010-2012, that of old seedlings decreased by almost two-thirds, but only in 2008-2010, and was generally unrelated to conspecific seedling density. In 2010-2012 relative growth rates in new seedlings' heights decreased with increasing basal area, as well as with increasing seedling density, together with increasing leaf numbers, whereas old seedlings' growth was unrelated to either conspecific density or basal area. Saplings of below-average height had reduced survivorship with increasing basal area (probability decreasing from approx. 0.4 to 0.05 over the basal area range tested), but only sapling growth in terms of leaf numbers decreased with increasing basal area. These static and dynamic results indicate that NDD is operating within this system, possibly stabilizing the M. bisulcata population. However, these NDD patterns are unlikely to be caused by symmetric competition or by consumers. Instead, an alternative mechanism for conspecific adult-juvenile negative feedback is proposed, one which involves the interaction between tree phenology and ectomycorrhizal linkages. [ABSTRACT FROM AUTHOR]

Mechanistic models can help resolve controversy over the responses of mast seeding plants to future environmental change., We evaluate drivers of mast seeding by: developing and validating a new mechanistic resource-based model of mast seeding using four 40-yr Chionochloa (snow tussock) datasets; and comparing the performance of competing empirically-based statistical models, that aim to approximate the mechanisms underlying mast seeding, in explaining simulated and observed data., Our mechanistic model explained 90-99% of the variation in Chionochloa flowering, with higher rates of stored resource mobilisation and lower probability of climatic induction of flowering occurring at lower fertility sites. Inter-annual variation in floral induction and the degree to which seeding is resource-limited explained shifts in the relative performance of different empirical models fitted to data simulated from the mechanistic model. Empirical models explicitly capturing the interaction between the floral induction cue and internal resource state underlying the resource-limited induction mechanism had > 8.7× the statistical support of alternatives when fitted to Chionochloa datasets., We find support for resource-limited floral induction with multiple empirical models consistent with this same mechanism. As both resource acquisition and flowering cues are climate sensitive, we expect climate change to impact upon patterns of mast seeding. [ABSTRACT FROM AUTHOR]

The article provides information on the infanticides committed by the male red squirrels before a mast year. Topics discussed include their anticipation for White Spruce's production of cones, the death of pups after the female stops lactating, and the infanticide occuring frequently in species in which the male can monopolize the female species.

Mast-seeding is the synchronized and intermittent production of a large seed crop by a population of plants. The cascading effects of masting on wildlife have been well documented in granivorous rodents. Yet, the effects of mast-seeding are potentially further reaching, since a number of generalist species can take advantage of mast years. We employed a full-text search algorithm to identify all papers that discussed effects of mast-seeding on wildlife, in addition to typical searches of titles and abstracts. We aimed to evaluate the breadth of wildlife species for which mast years are thought to be important drivers. In addition, we tested three hypotheses derived from past reviews: 1) species with lower reproductive potential (lower average litter size) are more likely to show aggregative responses to mast-seeding, 2) species with lower body sizes (lower mobility) are more likely to show reproductive responses, and 3) indirect consumers of mast (predators) are more likely to show aggregative responses than direct consumers. We found 186 articles including reports of response of 122 species of vertebrates to mast-seeding. Expectations were partly confirmed: relationships 1) and 2) held for mammals, but not for birds. However, 3) direct consumers were more likely than indirect consumers to show aggregative responses. Our tests of the first two hypotheses question the generality of past predictions for taxa other than mammals. Our test of the third hypothesis suggests that responses of direct and indirect consumers might depend on the type of resource pulse. Many of the examples in our analysis come from systems in which wildlife responses to mast have been less rigorously documented than the examples in past reviews. They suggest the range of wildlife responses to mast-seeding are more taxonomically and ecologically diverse than past reviews have widely recognized and point to directions for future research. [ABSTRACT FROM AUTHOR]

The predator satiation and predator dispersal hypotheses provide alternative explanations for masting. Both assume satiation of seed-eating vertebrates. They differ in whether satiation occurs before or after seed removal and caching by granivores (predator satiation and predator dispersal, respectively). This difference is largely unrecognized, but it is demographically important because cached seeds are dispersed and often have a microsite advantage over nondispersed seeds. We conducted rodent exclosure experiments in two mast and two nonmast years to test predictions of the predator dispersal hypothesis in our study system of yellow-necked mice ( Apodemus flavicollis) and European beech ( Fagus sylvatica). Specifically, we tested whether the fraction of seeds removed from the forest floor is similar during mast and nonmast years (i.e., lack of satiation before seed caching), whether masting decreases the removal of cached seeds (i.e., satiation after seed storage), and whether seed caching increases the probability of seedling emergence. We found that masting did not result in satiation at the seed removal stage. However, masting decreased the removal of cached seeds, and seed caching dramatically increased the probability of seedling emergence relative to noncached seeds. European beech thus benefits from masting through the satiation of scatterhoarders that occurs only after seeds are removed and cached. Although these findings do not exclude other evolutionary advantages of beech masting, they indicate that fitness benefits of masting extend beyond the most commonly considered advantages of predator satiation and increased pollination efficiency. [ABSTRACT FROM AUTHOR]

Highly variable patterns of seed production ('masting') have been hypothesized to be driven by internal dynamics of resource storage and depletion. This hypothesis predicts that if seed production is artificially reduced, then the availability of unused stored resources should result in subsequent enhancement of the seed crop. We tested this prediction in two oak species with contrasting patterns of annual seed production (highly variable and relatively constant) by means of controlled burns at various frequencies over a 17-year period. We found that controlled burns reduced acorn production by both species in the year of the burn. In the species with relatively constant productivity, acorn production returned to baseline levels in the year following a burn; however, in the species with highly variable productivity, acorn production significantly increased the year following a burn. These results support a key prediction of the stored resource hypothesis by means of a long-term experimental test in wild tree populations. [ABSTRACT FROM AUTHOR]

The differential temperature (Δ T) model, based on the assumption that masting plants respond to the difference in the temperatures during the growing seasons 1 and 2 years prior to seed production, has recently been proposed to explain the proximate factor of masting. In this study, we used a 28-year series of data on pollen cone and seed production in Cryptomeria japonica D. Don in Japan and compared several models based on temperatures and resources to test whether Δ T acts as a cue or is a proxy for resource limitation. Of all the models tested, models including Δ T, previous summer absolute temperature Tn-1, and reproduction in the previous year provided the best fit. The number of pollen cones and seeds produced was proportional to the difference in the mean daily maximum temperature during June to August between the preceding two years. In addition, to test whether the double mast events in consecutive years was less common than consecutive warm summers, we used our dataset and 12 datasets of pollen dispersal of 17 years or longer of C. japonica in Japan. Although consecutive warm summers occurred in 4.4% of pairs, double mast events occurred in 1.0%. The Δ T model was a considerably better predictor of the rare phenomenon of double mast events, which occur only after a specific sequence of cold-moderate-hot absolute summer temperatures. Thus, Δ T acts as cue for masting in C. japonica. [ABSTRACT FROM AUTHOR]