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Understanding the factors that determine species’ range limits is a key issue in ecology, and is fundamental for biodiversity conservation under widespread global environmental change. Elucidating how altitudinal variation affects demographic processes may provide important clues for understanding the factors limiting current and future species distributions, yet population dynamics at range limits are still poorly understood. Here, we tested the hypothesis that lower abundance at a species’ upper altitudinal range limit is related to lower vital rates. We compared the dynamics of two populations of the tropical palm Euterpe edulis, located near and at the edge of its altitudinal limit of distribution in the Brazilian Atlantic Forest. Data from four annual censuses, from 2012 to 2015, were used. We used matrix population models to estimate asymptotic population growth rates and the elasticity values for the vital rates of the two populations of E. edulis. Life table response experiments were used to compare population performance by measuring the contribution of each vital rate to population growth rates. Population growth rates were not significantly different from one in either population, indicating that both populations were stable during the study period. However, the abundance of all ontogenetic stages was lower at the altitudinal range limit, which was related to decreases in some vital rates, especially fecundity. Additionally, there were higher elasticity values for the survival of immatures and reproductive individuals, compared to all other vital rates, in both populations. Synthesis. Our results show that even a small‐scale environmental variation near range limits is sufficient to drive changes in the demography of this threatened palm. A minor increase in elevation approaching the limit of altitudinal distribution may reduce environmental suitability and affect population vital rates, thus contributing to setting upper altitudinal range limits for plants.

The combination of species distribution models based on climatic variables, with spatially explicit analyses of habitat loss, may produce valuable assessments of current species distribution in highly disturbed ecosystems. Here, we estimated the potential geographic distribution of the threatened palm Euterpe edulis Mart. (Arecaceae), an ecologically and economically important species inhabiting the Atlantic Forest biodiversity hotspot. This palm is shade-tolerant, and its populations are restricted to the interior of forest patches. The geographic distribution of E. edulis has been reduced due to deforestation and overexploitation of its palm heart. To quantify the impacts of deforestation on the geographical distribution of this species, we compared the potential distribution, estimated by climatic variables, with the current distribution of forest patches. Potential distribution was quantified using five different algorithms (BIOCLIM, GLM, MaxEnt, Random Forest and SVM). Forest cover in the biome was estimated for the year 2017, using a recentlyreleased map with 30 m resolution. A total of 111 records were kept to model climatic suitability of E. edulis, varying from 6 to 1500 m a.s.l and spanning almost the entire latitudinal gradient covered by the Atlantic Forest (from 7.72º S to 29.65º S). Based on climatic suitability alone, ca. 93 million hectares, or 66% of the area of the Atlantic Forest, would be suitable for the occurrence of E. edulis. However, 76% of this climatically suitable area was deforested. Therefore, currently, only ca. 15% of the biome retains forest patches that are climatically suitable for E. edulis. Our analyses show that E. edulis has suffered a dramatic loss of potential distribution area in the Atlantic Forest due to widespread deforestation. Our results provided updated information on the distribution of E. edulis, and may be used to identify which forested and deforested areas could receive priority in future conservation and restoration efforts.

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Background and Aims Timing of seed dispersal determines the environmental conditions that plants face during early life stages. In seasonal environments, selection is expected to favor dispersal timing that is matched to environmental conditions suitable for successful recruitment. Our aim was to test whether the timing of seed dispersal influences seedling establishment success in two populations of Euterpe edulis that are located at contrasting altitudes, that have different seed-dispersal phenologies, and that are subjected to distinct climatic conditions. Methods We sowed E. edulis seeds in contrasting altitudes on different dates, and monitored seed germination, emergence, and seedling establishment at each altitude over four years. At the high-altitude site, five seed-dispersal cohorts were established during the natural dispersal period. At the low-altitude site, three seed-dispersal cohorts were established during the natural dispersal, and two were established either before or after natural dispersal. Key Results At the high-altitude site, seed-dispersal timing did not affect seed germination, seedling emergence, or seedling establishment success. In contrast, at the low-altitude site, late seed dispersal near the end of the wet season resulted in a lower probability of seedling establishment, possibly due to the exposure of seeds, germinants and seedlings to unfavorable drought conditions. In addition, at the low-altitude site, natural seed-dispersal period was poorly matched to favorable environmental conditions for seedling establishment. Conclusions The greater effect of seed-dispersal timing on seedling establishment at the low-altitude site is likely related to a more seasonal and drought-prone environment that favors a restricted period of seed dispersal. The magnitude of the effect of dispersal timing on seedling establishment success was modulated by environmental conditions that vary across altitude. Furthermore, reproductive phenology appears to be exposed to more intense selection at the lower limit of altitudinal range, due to a more restrictive window of opportunity for successful seedling establishment.

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