Forest Biology Center

Ever wondered why some years your favorite forest is overflowing with beech nuts, and other years it’s almost barren? This feast-or-famine cycle, known as masting, is not just random. Our recent research reveals a fascinating pattern: European beech trees are synchronizing their seed production across vast distances, but intriguingly, they do so differently for bumper crop years compared to lean ones.

Masting refers to the high variation in seed production that some perennial plants exhibit from year to year. Imagine a forest where, one year, beech trees are heavy with seeds, and the next, they’re nearly bare. This phenomenon isn’t just a local quirk; it can happen simultaneously across regions spanning hundreds of kilometers. Researchers have been curious to understand whether these peaks (high seed years) and troughs (low seed years) in seed production are synchronized differently.

We delved into this question by studying 99 populations of European beech trees (Fagus sylvatica) across Europe. We discovered that while mast peaks (years of high seed production) are synchronized up to 1000 kilometers apart, the years of seed scarcity are synchronized across even larger distances, up to 1800 kilometers.

This spatial synchrony is more concentrated in northeastern Europe for mast peaks, while seed scarcity spans almost the entire range of the species. This extensive synchrony in low seed years means that when beech trees experience a bad year, it’s felt widely, creating resource famines that can ripple through ecosystems.

Such extensive synchrony in seed scarcity has important implications. It can lead to resource pulses or famines, impacting food webs significantly. Animals that rely on beech seeds for food may face widespread shortages, affecting their populations and behavior. This, in turn, can influence predator-prey dynamics, biodiversity, and even forest health.

Understanding these patterns is crucial in the context of climate change. As weather patterns shift, the synchrony in masting may alter, potentially leading to more frequent or severe resource pulses and famines. This can affect not only the plants and animals directly involved but also the broader ecological and climatic systems.

Our recent paper on mast seeding in perennial plants presents a model that integrates proximate factors (environmental variation, weather cues, resource budgets) with ultimate drivers (predator satiation, pollination efficiency). This model illustrates how the relationships between mast seeding and weather influence species’ responses to climate warming, ranging from no change to reduced interannual variation or reproductive failure. The role of environmental prediction as a driver of mast seeding is being reassessed; future studies need to estimate the accuracy of these predictions and the benefits they confer. Understanding how mast seeding adapts to shifting environmental conditions is now a central question in plant adaptation to climate change.

W czasopiśmie Animal Cognition ukazała się publikacja, w której wykazaliśmy, że ptaki uczą się rozpoznawać nowe, wcześniej nieznane im dźwięki (fragmenty punkrockowych piosenek) jako sygnały akustyczne świadczące o zagrożeniu na drodze uczenia socjalnego, jeśli pojawieniu się w środowisku nowego dźwięku towarzyszy reakcja alarmowa innych osobników. Ponadto wykazaliśmy, że nabyta na drodze przekazu socjalnego zdolność rozpoznawania nowych sygnałów o zagrożeniu utrzymuje się w ekologicznie istotnej perspektywie czasowej. Praca do poczytania tutaj: https://doi.org/10.1007/s10071-024-01858-6

Our new paper explores how seed production in perennial plants, like European beech (Fagus sylvatica), synchronizes across vast distances, affecting ecosystem functions. The study reveals that the summer solstice serves as a celestial cue, triggering synchronized responses to weather conditions among widely separated populations of European beech. This 'starting gun’ initiates ecological events with high spatial synchrony across the continent, highlighting the significance of celestial cues and weather coordination in shaping ecosystem dynamics.
Read the full story: https://rdcu.be/dADZx

Masting, the synchronized seed production among plants, is often seen as a reproductive strategy. But is it inherited? We studied 110 Sorbus aucuparia L. trees for 22 years to find out. We discovered that trees with similar genetics and growing conditions shared similar reproductive patterns. Also, trees of similar sizes had comparable fluctuations in fruiting from year to year, influenced partly by genetics. These findings suggest that masting behavior is inherited and can adapt to nature’s challenges, giving us new insights into how plants reproduce and thrive.

New study in European Journal of Forest Research dissects 22 years of rowan tree fecundity, emphasizing the pivotal role of DBH and the dominance of light availability. Notably, neighborhood crowding unveiled a correlation with pollinator competition. This research advances seed production ecology understanding, offering insights for effective fruit supply management. Read the full study:
https://link.springer.com/article/10.1007/s10342-024-01661-5

New paper in Ecology shows that reproductive performance of Wood Warblers – small, ground-nesting songbirds – is much lower in years following mast seeding than in years preceded by mast failures, as mast seeding indirectly increases predation pressure on Wood Warbler nests. Moreover, matrix population models revealed that regional variation in mast seeding frequency is a possible explanation for divergent population trends of Wood Warblers in different regions of Europe. The paper can be found here: https://doi.org/10.1002/ecy.4227

New paper in Nature Communications takes 517 plant species and links their interannual variation of seed production with functional traits. 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.

There is a write-up on that paper in the Nature blog, and the paper is here.

Phenology, corresponding to the study of periodic events, plays an important role in fitness and species distribution because it determines when a species grows and reproduces. Here, F. Jean et al. compiled a dataset of leaf phenology observations for European Beech and Silver fir. The data has been recorded at the tree level, from bud development to leaf unfolding date, along the Mont-Ventoux, a mountain in the South of France. 

A new paper in Methods and Ecology Evolution rediscovers CVk, a CV-based metric that has some interesting features making it worth looking at in masting studies. These include the reduced sample size needed to discover trends, especially worthy one given the logistical challenges of long-term seed production monitoring and the scarcity of such data.