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Abstract All species must partition resources among the processes that underly growth, survival, and reproduction. The resulting demographic trade‐offs constrain the range of viable life‐history strategies and are hypothesized to promote local coexistence. Tropical forests pose ideal systems to study demographic trade‐offs as they have a high diversity of coexisting tree species whose life‐history strategies tend to align along two orthogonal axes of variation: a growth–survival trade‐off that separates species with fast growth from species with high survival and a stature–recruitment trade‐off that separates species that achieve large stature from species with high recruitment. As these trade‐offs have typically been explored for trees ≥1 cm dbh, it is unclear how species' growth and survival during earliest seedling stages are related to the trade‐offs for trees ≥1 cm dbh. Here, we used principal components and correlation analyses to (1) determine the main demographic trade‐offs among seed‐to‐seedling transition rates and growth and survival rates from the seedling to overstory size classes of 1188 tree species from large‐scale forest dynamics plots in Panama, Puerto Rico, Ecuador, Taiwan, and Malaysia and (2) quantify the predictive power of maximum dbh, wood density, seed mass, and specific leaf area for species' position along these demographic trade‐off gradients. In four out of five forests, the growth–survival trade‐off was the most important demographic trade‐off and encompassed growth and survival of both seedlings and trees ≥1 cm dbh. The second most important trade‐off separated species with relatively fast growth and high survival at the seedling stage from species with relatively fast growth and high survival ≥1 cm dbh. The relationship between seed‐to‐seedling transition rates and these two trade‐off aces differed between sites. All four traits were significant predictors for species' position along the two trade‐off gradients, albeit with varying importance. We concluded that, after accounting for the species' position along the growth–survival trade‐off, tree species tend to trade off growth and survival at the seedling with later life stages. This ontogenetic trade‐off offers a mechanistic explanation for the stature–recruitment trade‐off that constitutes an additional ontogenetic dimension of life‐history variation in species‐rich ecosystems. 

ABSTRACT Leaves are critical to plant photosynthesis and the loss of leaf area can have negative consequences for an individual's performance and fitness. Variation in plant defenses plays a large role in protecting their leaves from attack by insect herbivores. However, trade‐offs in allocation among growth, reproduction, and defense may limit the availability of resources for any one aspect of a plant's life‐history strategy, which would lead to greater herbivory in those plants that allocate more resources to growth or reproduction than to defense. Patterns of sex‐biased herbivory in dioecious plants are well documented yet are known to vary in the direction (female or male) of their bias. A greater concentration of conspecifics may also increase herbivore attack through negative density dependence. In order to test the hypothesis that sex‐biased herbivory varies as a function of conspecific density, we measured standing herbivory on 2350 leaves on 302 trees of the dioecious understory treeIryanthera hostmannii(Myristicaceae) situated in a large forest dynamics plot in a lowland tropical rain forest in Ecuador. We found no difference in standing herbivory between the 169 male and 133 female trees, nor for focal trees surrounded by higher densities of conspecifics. The slow‐growing, shade‐tolerant growth patterns ofI. hostmanniimay contribute to suppressed differential expression of secondary sex characters in leaf defenses, leading to similar levels of herbivory between males and females. Considering the factors that most strongly affect herbivory in dioecious species is important in understanding the evolution of sex‐related traits more broadly. 

ABSTRACT Examining the cues and drivers influencing seed production is crucial to better understand forest resilience to climate change. We explored the effects of five climatic variables on seed production over 22 years in an everwet Amazonian forest, by separating direct effects of these variables from indirect effects mediated through flower production. We observed a decline in seed production over the study period, which was primarily explained by direct effects of rising nighttime temperatures and declining average vapour pressure deficits. Higher daytime temperatures were positively related to seed output, mainly through a flower‐mediated effect, while rainfall effects on seed production were more nuanced, showing either positive or negative relationships depending on the seasonal timing of rains. If these trends continue, they are likely to lead to significant changes in forest dynamics, potentially impacting both forest structure and species composition. 

Seedling demography data are provided in annual censuses of 600 seedling plots in an equatorial, ever-wet rainforest in eastern Ecuador, in Yasuní National Park. This long-term study uses standardized methodology from the Smithsonian ForestGEO network of plots, and in particular coordination with similar studies in Luquillo, Puerto Rico, and Barro Colorado Island, Panama. We address hypotheses about the maintenance of forest diversity and long-term variation, and link our data to companion studies of flowering and fruiting phenology and sapling and adult dynamics in the Yasuní Forest Dynamics 50-ha Plot. The project is ongoing, and additional data will be added as they are processed. 

We provide data on flowering and fruiting phenology from an equatorial, ever-wet rainforest in eastern Ecuador, in Yasuni National Park. This is the first long-term study (18 years) of phenology in a diverse equatorial neotropical forest. Although the site is ever-wet, there is some seasonal variation in rainfall and irradiance. One major question was to determine whether the seasonal variation in climate was sufficient to drive seasonality in reproduction in this hyper-diverse forest. The study began in 2000 with various funding, and became an LTREB-funded project in 2006. We used twice monthly censuses of 200 traps to document phenology. Parts of >1000 species were identified in the traps in the 18 year period (ending early in 2018), including trees, shrubs, lianas and epiphytes. Parts identified included buds, flowers, mature fruits and mature seeds, and aborted, damaged and immature fruits and seeds. The project is on-going, and additional data will be added as it is processed. 

Populations of forest trees exhibit large temporal fluctuations, but little is known about the synchrony of these fluctuations across space, including their sign, magnitude, causes and characteristic scales. These have important implications for metapopulation persistence and theoretical community ecology. Using data from permanent forest plots spanning local, regional and global spatial scales, we measured spatial synchrony in tree population growth rates over sub-decadal and decadal timescales and explored the relationship of synchrony to geographical distance. Synchrony was high at local scales of less than 1 km, with estimated Pearson correlations of approximately 0.6–0.8 between species’ population growth rates across pairs of quadrats. Synchrony decayed by approximately 17–44% with each order of magnitude increase in distance but was still detectably positive at distances of 100 km and beyond. Dispersal cannot explain observed large-scale synchrony because typical seed dispersal distances (<100 m) are far too short to couple the dynamics of distant forests on decadal timescales. We attribute the observed synchrony in forest dynamics primarily to the effect of spatially synchronous environmental drivers (the Moran effect), in particular climate, although pests, pathogens and anthropogenic drivers may play a role for some species. 

Understanding the mechanisms that promote the coexistence of hundreds of species over small areas in tropical forest remains a challenge. Many tropical tree species are presumed to be functionally equivalent shade-tolerant species that differ in performance trade-offs between survival in shade and the ability to quickly grow in sunlight. Variation in plant functional traits related to resource acquisition is thought to predict variation in performance among species, perhaps explaining community assembly across habitats with gradients in resource availability. Many studies have found low predictive power, however, when linking trait measurements to species demographic rates. Seedlings face different challenges recruiting on the forest floor and may exhibit different traits and/or performance trade-offs than older individuals face in the eventual adult niche. Seed mass is the typical proxy for seedling success, but species also differ in cotyledon strategy (reserve vs photosynthetic) or other seedling traits. These can cause species with the same average seed mass to have divergent performance in the same habitat. We combined long-term studies of seedling dynamics with functional trait data collected at a standard developmental stage in three diverse neotropical forests to ask whether variation in coordinated suites of traits predicts variation among species in demographic performance. Across hundreds of species in Ecuador, Panama, and Puerto Rico, we found seedlings displayed correlated suites of leaf, stem, and root traits, which strongly correlated with seed mass and cotyledon strategy. Variation among species in seedling functional traits, seed mass, and cotyledon strategy were strong predictors of trade-offs in seedling growth and survival. Our findings highlight the importance of cotyledon strategy in addition to seed mass as a key component of seed and seedling biology. These results also underscore the importance of matching the ontogenetic stage of the trait measurement to the stage of demographic dynamics. Synthesis: With strikingly consistent patterns across three tropical forests, we find strong evidence for the promise of functional traits to provide mechanistic links between seedling form and demographic performance. 

Abstract The Andes are a major dispersal barrier for lowland rain forest plants and animals, yet hundreds of lowland tree species are distributed on both sides of the northern Andes, raising questions about how the Andes influenced their biogeographic histories and population genetic structure. To explore these questions, we generated standardized datasets of thousands of SNPs from paired populations of 49 tree species co‐distributed in rain forest tree communities located in Panama and Amazonian Ecuador and calculated genetic diversity (π) and absolute genetic divergence (d_XY) within and between populations, respectively. We predicted (1) higher genetic diversity in the ancestral source region (east or west of the Andes) for each taxon and (2) correlation of genetic statistics with species attributes, including elevational range and life‐history strategy. We found that genetic diversity was higher in putative ancestral source regions, possibly reflecting founder events during colonization. We found little support for a relationship between genetic divergence and species attributes except that species with higher elevational range limits exhibited higherd_XY, implying older divergence times. One possible explanation for this pattern is that dispersal through mountain passes declined in importance relative to dispersal via alternative lowland routes as the Andes experienced uplift. We found no difference in mean genetic diversity between populations in Central America and the Amazon. Overall, our results suggest that dispersal across the Andes has left enduring signatures in the genetic structure of widespread rain forest trees. We outline additional hypotheses to be tested with species‐specific case studies. 

Summary Climate models predict that everwet western Amazonian forests will face warmer and wetter atmospheric conditions, and increased cloud cover. It remains unclear how these changes will impact plant reproductive performance, such as flowering, which plays a central role in sustaining food webs and forest regeneration. Warmer and wetter nights may cause reduced flower production, via increased dark respiration rates or alteration in the reliability of flowering cue‐based processes. Additionally, more persistent cloud cover should reduce the amounts of solar irradiance, which could limit flower production.We tested whether interannual variation in flower production has changed in response to fluctuations in irradiance, rainfall, temperature, and relative humidity over 18 yrs in an everwet forest in Ecuador.Analyses of 184 plant species showed that flower production declined as nighttime temperature and relative humidity increased, suggesting that warmer nights and greater atmospheric water saturation negatively impacted reproduction. Species varied in their flowering responses to climatic variables but this variation was not explained by life form or phylogeny.Our results shed light on how plant communities will respond to climatic changes in this everwet region, in which the impacts of these changes have been poorly studied compared with more seasonal Neotropical areas. 

Abstract Flowering and fruiting phenology have been infrequently studied in the ever‐wet hyperdiverse lowland forests of northwestern equatorial Amazonía. These Neotropical forests are typically called aseasonal with reference to climate because they are ever‐wet, and it is often assumed they are also aseasonal with respect to phenology. The physiological limits to plant reproduction imposed by water and light availability are difficult to disentangle in seasonal forests because these variables are often temporally correlated, and both are rarely studied together, challenging our understanding of their relative importance as drivers of reproduction. Here we report on the first long‐term study (18 years) of flowering and fruiting phenology in a diverse equatorial forest, Yasuní in eastern Ecuador, and the first to include a full suite of on‐site monthly climate data. Using twice monthly censuses of 200 traps and >1000 species, we determined whether reproduction at Yasuní is seasonal at the community and species levels and analyzed the relationships between environmental variables and phenology. We also tested the hypothesis that seasonality in phenology, if present, is driven primarily by irradiance. Both the community‐ and species‐level measures demonstrated strong reproductive seasonality at Yasuní. Flowering peaked in September–November and fruiting peaked in March–April, with a strong annual signal for both phenophases. Irradiance and rainfall were also highly seasonal, even though no month on average experienced drought (a month with <100 mm rainfall). Flowering was positively correlated with current or near‐current irradiance, supporting our hypothesis that the extra energy available during the period of peak irradiance drives the seasonality of flowering at Yasuní. As Yasuní is representative of lowland ever‐wet equatorial forests of northwestern Amazonía, we expect that reproductive phenology will be strongly seasonal throughout this region.