The research team, led by Marcela T. P. Oliveira and Jéssica L. S. Silva of the Federal University of Pernambuco, monitored 955 individual trees representing 77 species from 21 botanical families. The study sites included ten public squares and four urban parks, together covering roughly forty percent of the total area of squares and parks in Recife, a city of about 1.5 million people that sits at the heart of the Pernambuco Endemism Center of the Atlantic Forest. Every month from June 2016 to May 2018, the researchers recorded the intensity of flowering and fruiting using a semi-quantitative scale that classifies each phenophase into five categories, from complete absence to full expression across the crown. They then classified each species by geographic origin, pollination system, and seed dispersal mode, allowing them to ask whether urbanization affects different functional groups of plants in different ways.

The first and perhaps most sobering finding concerns the composition of the urban tree flora itself. Seventy-eight percent of the species growing in Recife’s green spaces are exotic to the northeastern Brazilian Atlantic Forest. In the squares, only thirteen of seventy-one species were native to the region, and even in the parks, natives made up less than a quarter of the flora. This imbalance matters because the native species that are present do not represent the full functional breadth of the regional forest. The researchers found no native Atlantic Forest trees with specialized pollination systems at all: there were no native species pollinated by birds, hawkmoths, flies, wasps, or wind in any of the fourteen sites. The only native bat-pollinated tree recorded was Chloroleucon foliolosum, a legume, and the only native beetle-pollinated species was the palm Acrocomia intumescens.

This functional gap has direct consequences for urban wildlife. Specialized pollinators such as hummingbirds and sphingid hawkmoths depend on particular floral morphologies, nectar concentrations, and phenological windows that only certain native plants provide. When a city’s tree palette excludes those plants entirely, the specialist pollinators lose their resource base, no matter how many flowers bloom in the streets. The study’s authors argue that this absence of native resources for specialized vectors, combined with the altered phenology of the natives that do occur, negatively affects the maintenance of local faunal diversity. In other words, a green city is not automatically a biodiverse city; the identity and temporal behavior of the plants matter as much as their abundance.

The second major finding is that urban conditions change the reproductive calendars of the trees themselves. When the researchers compared the phenological patterns observed in Recife with those documented in the literature for the same species in natural ecosystems, they found that around seventy percent of the species for which comparative data existed had changed their flowering or fruiting patterns. The most common transition was from an annual pattern, meaning one reproductive event per year, to a sub-annual pattern, meaning more than one event per year. Forty-seven species changed their flowering pattern and forty-nine changed their fruiting pattern, and among the species that shifted, more than half were native to the northeastern Atlantic Forest. A chi-square test confirmed that this frequency of change was statistically significant.

Several concrete examples illustrate the scale of these shifts. Libidibia ferrea, a leguminous tree that flowers once a year in its natural habitat, flowered multiple times per year in Recife’s squares. Cenostigma pyramidale, which in the seasonally dry Caatinga blooms for a single four-month period, flowered continuously in the city. Sarcomphalus joazeiro, a fruiting tree of the Caatinga that produces fruit once a year in nature, fruited twice a year under urban conditions. The researchers suggest that for these species, many of which evolved under arid or seasonal conditions where water is limiting, the irrigated, nutrient-rich soils of urban parks remove the environmental constraints that normally synchronize their reproduction.

The mechanisms behind these phenological reorganizations are likely multiple and interacting. Urbanization generates heat islands, elevated concentrations of polluting gases, reduced humidity, drier soils in some contexts, altered nitrogen deposition, and reduced soil carbon, all of which can act as cues that modify plant phenological responses. At the same time, manual irrigation is common in Recife’s public squares and parks, effectively abolishing the dry season that structures reproduction in much of the regional flora. The result, at the community level, is a striking loss of seasonality: flowers were available in every month of the two-year study, and fruit was produced continuously except for a single species, Aspidosperma pyrifolium, which paused entirely. Only one species, the wind-pollinated exotic Casuarina equisetifolia, restricted its flowering to a defined five-month window.

Synchronization among individuals also told an important story. Using an index that accounts for both the intensity and the temporal overlap of phenophases, the researchers found that native trees showed lower flowering and fruiting synchrony than exotic trees. Species pollinated by birds, hawkmoths, and wasps, all of which were exclusively exotic, showed relatively high synchrony among individuals, whereas trees pollinated by bees and diverse small insects, including the natives, showed low synchrony. Fruiting synchrony was low across all dispersal modes, with values below 0.3 for animal-dispersed, self-dispersed, and wind-dispersed groups alike. Low synchrony means that individual trees in the same population are reproducing at different times, which can reduce the efficiency of pollinator-mediated pollen transfer and fragment the resource pulses that fruit-eating animals depend on.

The dominance of exotic species in shaping these urban phenological rhythms raises concerns that extend beyond the city limits. Exotic plants can compete with natives for shared pollinators, alter the abundance and composition of pollinator communities, and reduce the reproductive success of native species, particularly when flowering periods overlap. Dispersing animals often prefer the fruits of exotic species, which can further skew seed dispersal away from native trees. The authors also note subtler risks: the nectar or floral resources offered by some exotic ornamentals may be toxic or nutritionally inferior to those of native plants, potentially endangering pollinator health. Because the exotic species in Recife’s green spaces are more numerous and possess a wider range of reproductive strategies, they effectively command the community-level pattern of flowering and fruiting, setting the temporal template that native plants and animals must navigate.

The study’s practical message is directed at urban planners and arborists across the tropics. Urban afforestation programs, the authors argue, must prioritize native species from each phytogeographic domain and select a palette that makes floral and fruit resources available in a complementary way throughout the year, rather than relying on a handful of exotic ornamentals that produce a continuous but ecologically shallow resource stream. The historical roots of the problem run deep: much of the exotic flora in Brazilian cities traces back to colonial-era landscaping traditions, and even celebrated twentieth-century designs by the landscape architect Roberto Burle Marx, who created several of the squares studied here, favored showy plants from other Brazilian domains such as the Caatinga and the Amazon rather than the local Atlantic Forest. As climate change accelerates and cities continue to expand, long-term phenological monitoring will be essential to track how these urban plant communities respond, and to ensure that the green infrastructure of tropical cities supports, rather than undermines, the pollinators and seed dispersers on which both urban and natural ecosystems depend.

Subject of Research: Urbanization effects on the reproductive phenology of tropical tree species in urban green spaces compared with natural Atlantic Forest areas

Article Title: Same tree species, different reproductive phenological patterns between tropical urban green spaces and natural areas

Article References: Oliveira, M. T. P., Silva, J. L. S., Cruz-Neto, O., & Lopes, A. V. (2025). Same tree species, different reproductive phenological patterns between tropical urban green spaces and natural areas. Discover Ecology, 1(1), Article 13. https://doi.org/10.1007/s44396-025-00014-9

Image Credits: AI Generated

DOI: 10.1007/s44396-025-00014-9

Keywords: phenology, urban ecology, Atlantic Forest, pollination, flowering, fruiting, native species, exotic species, urban green spaces, tropical trees, seed dispersal, biodiversity

The research, published in the journal Discover Forests, was conducted by a team led by Kolawolé Valère Salako of the University of Abomey-Calavi in Benin. Rather than treating seeds as interchangeable units, the researchers measured them the way a breeder might measure livestock, recording length, width, thickness, and weight for an extraordinary 9,330 seeds gathered from 63 mother trees across five protected areas and three distinct climatic zones in Benin, ranging from the humid Guineo-Congolian zone in the south to the dry Sudanian zone in the north. Each seed was individually labeled and measured with calipers precise to a hundredth of a millimeter, and mother trees were kept at least 100 meters apart to avoid sampling related individuals. The result is one of the most granular portraits of seed variation ever assembled for a threatened tropical timber species.

The first headline finding concerns climate. Across the rainfall gradient, seed traits shifted in a clear and consistent direction: the longest, heaviest, and thickest seeds came from the wettest zone, while the smallest and lightest came from the driest. Seed length averaged just over 20.8 millimeters in the wettest zone compared with about 18.8 millimeters in the driest, and seed weight followed the same trajectory. The only trait that refused to follow the trend was seed width, which remained remarkably stable no matter where the mother tree stood. The authors interpret this gradient as a possible adaptation strategy: under the biotic and abiotic stresses of drier climates, plants commonly produce smaller seeds, a pattern previously documented in other West African multipurpose trees such as tamarind. Seed weight, in particular, stood out as the most variable trait of all, with coefficients of variation exceeding 25 percent across zones and provenances.

But the deeper surprise lay in where the variation actually lived. Using linear mixed models and variance component analysis, the team decomposed the total phenotypic variation into its hierarchical sources: climatic zones, provenances within zones, trees within provenances, and seeds within trees. The answer upended the intuitive assumption that broad climate is the dominant driver. More than 75 percent of the variation occurred within climatic zones rather than among them, and the single largest share, ranging from roughly 31 to 56 percent depending on the trait, occurred within individual mother trees. Variation among trees accounted for 19 to 22 percent, and variation among climatic zones never exceeded 25 percent. In other words, a single Afzelia tree in one forest can produce a wider spread of seed forms than exists between entire regions hundreds of kilometers apart.

To probe this within-tree diversity further, the researchers turned to a technique borrowed from ecology: hypervolume analysis. After standardizing the four seed measurements and compressing them into a two-dimensional phenotypic space using principal component analysis, they constructed a hypervolume, essentially a multidimensional envelope, for each mother tree, quantifying how much of the total trait space that tree’s seeds occupied. The differences were striking. The most phenotypically expansive tree, designated AG4, produced a hypervolume of 45.06, while the most homogeneous, AG12, occupied only 9.39. Trees with large hypervolumes produce seeds spanning a broad range of sizes and shapes, whereas trees with small hypervolumes produce seeds of striking uniformity. Crucially, climatic zone had no statistically significant effect on either the hypervolumes or the within-tree coefficients of variation, pointing instead to microclimate and intrinsic maternal effects, the local conditions surrounding each individual tree and its own genetic makeup, as the primary architects of seed morphological diversity.

The team also estimated repeatability for each trait, a statistical proxy for heritability that asks how much of the variation in a trait is attributable to differences among mother trees rather than to environmental noise within them. Repeatability was highly significant for all four traits but varied in magnitude. Seed thickness and width showed low values, approaching zero in some cases, while seed length and seed weight showed moderate repeatability, between 0.33 and 0.37. That moderate figure matters enormously for restoration practice. It means that seed length and weight are partly inherited from the mother tree, so a nursery manager selecting seeds from trees that reliably produce large, heavy seeds has a reasonable chance of capturing that characteristic in the next generation. Traits with near-zero repeatability, by contrast, would offer no such predictive power.

Why does seed size matter so much for restoration? Previous work on Afzelia africana has shown that larger seeds germinate at higher final percentages, germinate faster on average, and produce seedlings with stronger early growth. Because the success of enrichment planting and assisted regeneration programs hinges on getting seedlings established in often harsh, fire-prone, and grazed landscapes, the morphological quality of the seed lot is not a trivial detail; it can be the difference between a restored stand and a failed one. The moderate heritability of length and weight, combined with their high variability, makes these traits the most promising targets for selection. The authors suggest that the wide within-tree variation itself may be an adaptive bet-hedging strategy: rather than putting all reproductive effort into one optimal seed type, a mother tree spreads the risk across a portfolio of offspring forms, ensuring that at least some are suited to whatever conditions the future holds.

Synthesizing the coefficient of variation and hypervolume results, the researchers identified nine mother trees as the most promising seed sources for restoration programs: AG4, RB1, AG3, AG7, PE14, 3R6, AG10, DK2, and 3R5. These elite individuals combine high morphological diversity with substantial intra-individual variability, meaning their seeds sample a wide slice of the species’ phenotypic space. Collecting from such trees, the argument goes, would maximize the adaptive potential of restored populations, giving the next generation the raw variation it needs to cope with uncertain and changing conditions. The authors are careful to note, however, that phenotypic diversity alone is not a complete selection criterion; germination performance, reciprocal transplantation trials, and genetic diversity assessments should complement the morphological data before any tree is crowned a definitive seed orchard founder.

The broader implications reach well beyond a single species. Restoration practitioners worldwide increasingly recognize that where seeds come from, and which individuals they come from, shapes the long-term resilience of planted forests. This study adds a crucial nuance: sourcing decisions based only on broad climatic matching, the standard provenance approach, would miss most of the relevant variation, because the majority of phenotypic diversity in Afzelia seeds resides within individual trees, driven by maternal micro-environments rather than regional gradients. For a vulnerable foundation species struggling to regenerate across sub-Saharan Africa, the message is both practical and hopeful. The genetic and phenotypic raw material for recovery may already be standing in the forest, scattered among a handful of remarkable mother trees, waiting to be identified, protected, and propagated. Future work combining common garden experiments with reciprocal transplants will test whether the elite trees identified here pass their advantages on through the full life cycle, from seed to sapling to canopy giant.

Subject of Research: Intraspecific phenotypic variation and repeatability of seed traits in Afzelia africana across climatic gradients in Benin

Article Title: Seed phenotypic variation and traits repeatability in Afzelia africana along a climatic gradient provide insights for seed sourcing in forest restoration

Article References: Salako, K. V., Lissanon, J.-E., Gandji, M. R. M., Kolawole, A. M., Akouete, P. L. E., Dogbo, F. S., Akakpo, A. D., & Glèlè Kakai, R. (2026). Seed phenotypic variation and traits repeatability in Afzelia africana along a climatic gradient provide insights for seed sourcing in forest restoration. Discover Forests, 2(1), Article 72. https://doi.org/10.1007/s44415-026-00131-7

Image Credits: AI Generated

DOI: 10.1007/s44415-026-00131-7

Keywords: Afzelia africana, seed phenotypic variation, forest restoration, climatic gradient, repeatability, heritability, seed sourcing, Benin, hypervolume analysis, maternal effects, phenotypic plasticity, tropical trees