Significance: Physiological decline in large, old trees could involve diminished reproductive effort, but evidence is lacking. A global analysis finds that fecundity decline in large trees is pervasive, consistent with physiological decline, thus providing new evidence for tree senescence. For the 20% of species not showing fecundity declines, this lack of evidence was linked not to specific species groups, but rather to lack of large trees in the data. Large trees remain important for their structural attributes, but results highlight the critical role of intermediate trees for their contribution to reproduction.

Significant gaps remain in understanding the response of plant reproduction to environmental change. This is partly because measuring reproduction in long‐lived plants requires direct observation over many years and such datasets have rarely been made publicly available. Here we introduce MASTREE+, a data set that collates reproductive time‐series data from across the globe and makes these data freely available to the community. MASTREE+ includes 73,828 georeferenced observations of annual reproduction (e.g. seed and fruit counts) in perennial plant populations worldwide. These observations consist of 5971 population‐level time‐series from 974 species in 66 countries. The mean and median time‐series length is 12.4 and 10 years respectively, and the data set includes 1122 series that extend over at least two decades (≥20 years of observations). For a subset of well‐studied species, MASTREE+ includes extensive replication of time‐series across geographical and climatic gradients. Here we describe the open‐access data set, available as a.csv file, and we introduce an associated web‐based app for data exploration. MASTREE+ will provide the basis for improved understanding of the response of long‐lived plant reproduction to environmental change. Additionally, MASTREE+ will enable investigation of the ecology and evolution of reproductive strategies in perennial plants, and the role of plant reproduction as a driver of ecosystem dynamics.

The predator satiation hypothesis states that synchronous periodic production of seeds is an adaptive strategy evolved to reduce the pressure of seed predators. The seed production pattern is crucial to the predator satiation hypothesis, but there are few studies documenting the success of individuals that are in synchrony and out of synchrony with the whole population. This study is based on long-term data on seed production of Sorbus aucuparia and specialised pre-dispersal seed predation by Argyresthia conjugella, in a subalpine spruce forest in the Western Carpathians (Poland). At the population level, we tested whether functional and numerical responses of predators to the variation of fruit production operate. At the individual level, we tested whether individuals with higher interannual variability in their own seed crops and higher synchrony with the population have higher percentages of uninfested fruits. The intensity of pre-dispersal seed predation was high (average 70 %; range 19–100 %). There were both functional and numerical responses of predators to the variation of fruit production at the population level. We found that individuals that were expected to be preferred under seed predator pressure had higher reproductive success. With increasing synchrony of fruit production between individual trees and the population, the percentage of infested fruits decreased. There was also a negative relationship between the interannual variation in individual fruit production and the percentage of infested fruits. These results confirm selection for individuals with a masting strategy. However, the population does not seem well adapted to strong seed predation pressure and we suggest that this may be a result of prolonged diapause of A. conjugella.

Synchronized and variable reproduction by perennial plants, called mast seeding, is a major reproductive strategy of trees. The need to accumulate sufficient resources after depletion following fruiting (resource budget), the efficiency of mass flowering for outcross pollination (pollen coupling), or the external factors preventing reproduction (environmental veto) could all synchronize masting. We used seed production data for four species (Quercus ilex, Quercus humilis, Sorbus aucuparia, and Pinus albicaulis) to parametrize resource budget models of masting. Based on species life-history characteristics, we hypothesized that pollen coupling should synchronize reproduction in S. aucuparia and P. albicaulis, while in Q. ilex and Q. humilis, environmental veto should be a major factor. Pollen coupling was stronger in S. aucuparia and P. albicaulis than in oaks, while veto was more frequent in the latter. Yet in all species, costs of reproduction were too small to impose a replenishment period. A synchronous environmental veto, in the presence of environmental stochasticity, was sufficient to produce observed variability and synchrony in reproduction. In the past, vetoes like frost events that prevent reproduction have been perceived as negative for plants. In fact, they could be selectively favored as a way to create mast seeding.

The Whiskered Tern population in Poland has rapidly increased from 40 breeding pairs in 1990 to over 1,600 in 2007, with strongest local population in the Upper Vistula River Valley. Owing to rather low pre-breeding and adult apparent survival rates estimated for this population (0.54 and 0.80, respectively) and a delay in accession to reproduction (recruitment completed at age 3), matrix modelling indicated an intrinsic growth rate ofλ_calc = 1.02. Observed growth rates of both the Polish and the Upper Vistula River Valley populations wasλ_obs = 1.29. Using the deterministic population projection matrix including immigrant class, we estimated that, on average, 44 immigrants should enter the Upper Vistula River Valley population annually to match the observed growth. With survival rates increased (Φ_P = 0.63,Φ_B = 0.90) as to mimic no emigration and reduced dispersal, the estimated number of immigrants was only eight, indicating that substantial emigration rates are likely. A majority of the breeding sites were recorded in man-made water bodies. Colonisation has started in the southeast and proceeded towards the northwest. The strong, stable population in western Ukraine may explain high numbers of immigrants that could originate from there. Other factors favouring quick colonisation of Poland include availability of suitable breeding sites, the wide flexibility of the species with respect to breeding habitat, plentiful food, and high breeding success in the Upper Vistula River Valley. It also seems likely that westward shifts in both breeding and wintering ranges could add to the strong population increases in Eastern Europe.