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Average number of individuals and confidence interval of Brosimum rubescens, other woody species, and liana-only regeneration in four classes (seedlings: height B 30 cm; saplings: [ 30 to B 60 cm; poles or young stems: [ 60 to B 200 cm; treelets: height [ 200 cm and diameter \ 5 cm;
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The long-term dynamics of regeneration in tropical forests dominated by single tree species remains largely undocumented, yet is key to understanding the mechanisms by which one species can gain dominance and resist environmental change. We report here on the long-term regeneration dynamics in a monodominant stand of Brosimum rubescens Taub. (Morac...
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... total species richness varied little (Table 1), except for the treelet size class when lianas were included (cf Fig. 2), there was substantial species turnover through time for all regeneration classes (Supp. Fig. S.3). For instance, we observed: (1) 13 species in the first survey that were not observed in the second; (2) 15 in the second that were not observed in the first; (3) 18 in the second not observed in the third; (4) 14 in the third not observed in the second; (5) eight in the third not observed in the fourth; and (6) 18 species in the ...
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... in the fourth survey that were not observed in the third. This resulted in an average rate of change in species composition of nearly three species per year. Thus, while we find that overall species diversity was remarkably stable, species composition changed substantially, and this holds whether or not lianas are included in the analysis (Supp. Fig. ...
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... of the changes observed for tree seedlings was due to a sharp decrease in the Brosimum rubescens population over time (Fig. 3). There were significantly more B. rubescens seedlings in the first census than in any other, with particularly low densities of seedlings and saplings by the time of the final two surveys (Fig. 3). Over the 21 year period, the proportion of B. rubescens seedlings as a fraction of the total population declined from 82 to 45%. In ...
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... of the changes observed for tree seedlings was due to a sharp decrease in the Brosimum rubescens population over time (Fig. 3). There were significantly more B. rubescens seedlings in the first census than in any other, with particularly low densities of seedlings and saplings by the time of the final two surveys (Fig. 3). Over the 21 year period, the proportion of B. rubescens seedlings as a fraction of the total population declined from 82 to 45%. In addition, B. rubescens seedlings as a fraction of the whole community declined from 85% in 1997 to just 29% in 2018. Part of this relative decline of B. rubescens seedlings was due to increase in the ...
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... significant differences between surveys in each regeneration class (Repeated-Measures PERMANOVA). Note that lianas form a small fraction of woody regeneration early on but become increasingly more important especially in the smallest size classes the forest increased from 1 to 37% (Table 1), with a significant increase in all regeneration classes (Fig. 3). The remarkable gain in liana seedling and sapling relative abundance is thus not only because lianas increased greatly, but also because there was in numerical terms an even bigger reduction of B. rubescens and other tree species in these classes (Fig. ...
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... increased from 1 to 37% (Table 1), with a significant increase in all regeneration classes (Fig. 3). The remarkable gain in liana seedling and sapling relative abundance is thus not only because lianas increased greatly, but also because there was in numerical terms an even bigger reduction of B. rubescens and other tree species in these classes (Fig. ...
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Research Highlights: Functional diversity studies help to better understand how organisms respond to different environmental conditions. Conditions in tropical flooded forests are highly variable, including levels of nutrient availability, pH, and flood depth, but few studies have explored the impact of variation in these factors on plant functiona...
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... A number of studies have implied drought-induced functional type changes from treeto shrub-dominated communities [6]. Droughts may also alter phenology and lead to shifts in the species composition in regenerating tropical forests, for instance, favoring liana seedlings over tree seedlings [2,13]. Droughts may shift community traits in heavily logged forests towards being more ruderal which suggests a reversal in the trajectory of forest succession [2] and potentially indicates permanently arrested [2]. ...
... Seedlings and small saplings are probably more susceptible to changes in water availability than larger individuals due to their shallower roots which cannot reach deeper, moist soil layers and due to uneven competition with adult trees for soil moisture [1]. For some tree species, persistent water deficits limit germination of seeds which may inhibit regeneration in low rainfall years [13]. ...
... Seedlings and saplings in drier locations such as upper slopes and ridges may be particularly vulnerable during droughts [15]. While seeds and seedlings of many regenerating tree species are negatively impacted by drought conditions, other species may thrive under the same conditions, as seems to be the case for liana seedlings [2,13]. Although the exact mechanisms responsible remain unclear, lianas have been noted for their strong competitive capability in terms of competing for scarce below-ground water resources [13]. ...
The impact of climate change-driven droughts on regenerating forests is poorly understood due to the complexities involved in regeneration processes and the difficulties in measuring the relevant parameters with sufficient spatial and temporal resolution in a timely manner. Drought increases tree mortality in both undisturbed and disturbed forests and may influence forest regeneration dynamics from seed germination to the recruitment, growth, and survival of tree seedlings. Seedlings and small saplings may be more susceptible to changes in water availability than larger individuals due to their shallower roots that may be unable to reach the deeper, moist soil layers, and due to uneven competition with adult trees for soil moisture. The potential range shifts and local extinction of drought-sensitive species can also result in changes in forest species community composition and diversity loss at different scales. There is a need for precise and low-cost monitoring systems that facilitate better capturing of the complexities of such processes for restoration measures. The objective of this paper is to study the use of UAVs (Unmanned Aerial Vehicles) for monitoring responses of regenerating forests under increasing climate change-driven droughts. UAVs have several advantages over traditional field-based monitoring techniques and flexibility in selecting the required spatiotemporal resolution over other remote sensing methods, making them a promising tool for monitoring forest recovery. Although further research is required to ensure the accuracy and effectiveness of UAV-facilitated measures for monitoring forest regeneration, UAVs possess great potential in forest management in the event of increasing occurrences of climate-change driven droughts.
... Those forests with strongest dry seasons and the shortest trees experienced the most standing tree mortality. Seasonal water deficits vary across Amazonia but are typically most intense in the southern edge (Brando et al., 2014;Malhi et al., 2015;Marimon et al., 2020), explaining the strong influence of this variable on the death of shorter trees in this region. Under high MCWD, trees are more susceptible to hydraulic failure and carbohydrate deficiency due to the high evaporative demand and stomatal closure, respectively (McDowell et al., 2011(McDowell et al., , 2018, which may affect tree growth (Cailleret et al., 2017;Dobbertin, 2005;Feldpausch et al., 2016;Phillips et al., 2009) and may be exacerbated by high maximum temperatures in the region . ...
Tree death is a key process for our understanding of how forests are and will respond to global change. The extensive forests across the southern Amazonia edge—the driest, warmest and most fragmented of the Amazon regions—provide a window onto what the future of large parts of Amazonia may look like. Understanding tree mortality and its drivers here is essential to anticipate the process across other parts of the basin.
Using 10 years of data from a widespread network of long‐term forest plots, we assessed how trees die (standing, broken or uprooted) and used generalised mixed‐effect models to explore the contribution of plot‐, species‐ and tree‐level factors to the likelihood of tree death.
Most trees died from stem breakage (54%); a smaller proportion died standing (41%), while very few were uprooted (5%). The mortality rate for standing dead trees was greatest in forests subject to the most intense dry seasons.
While trees with the crown more exposed to light were more prone to death from mechanical damage, trees less exposed were more susceptible to death from drought.
At the species level, mortality rates were lowest for those species with the greatest wood density. At the individual tree level, physical damage to the crown via branch breakage was the strongest predictor of tree death.
Synthesis. Wind‐ and water deficit‐driven disturbances are the main causes of tree death in southern Amazonia edge which is concerning considering the predicted increase in seasonality for Amazonia, especially at the edge. Tree mortality here is greater than any in other Amazonian region, thus any increase in mortality here may represent a tipping point for these forests.
... The temporal and spatial maintenance of B. rubescens monodominant forests is linked to episodic recruitment in response to extreme climatic interference, probably associated with the impacts of prolonged drought disturbances related to El Niño Southern Oscillation phenomenon (ENSO) (Marimon et al. 2014a(Marimon et al. , 2020Marimon-Junior et al. 2019). Despite the morpho-anatomical and physiological attributes and environmental adaptations of B. rubescens, these drought events have caused a drastic reduction in the natural regeneration of the species, which may contribute to its population decline in the Amazonia-Cerrado transition (Marimon et al. 2012(Marimon et al. , 2020. ...
... The temporal and spatial maintenance of B. rubescens monodominant forests is linked to episodic recruitment in response to extreme climatic interference, probably associated with the impacts of prolonged drought disturbances related to El Niño Southern Oscillation phenomenon (ENSO) (Marimon et al. 2014a(Marimon et al. , 2020Marimon-Junior et al. 2019). Despite the morpho-anatomical and physiological attributes and environmental adaptations of B. rubescens, these drought events have caused a drastic reduction in the natural regeneration of the species, which may contribute to its population decline in the Amazonia-Cerrado transition (Marimon et al. 2012(Marimon et al. , 2020. Therefore, future climatic variations may affect the sensitive balance between mortality and recruitment, affecting the local and regional distribution of B. rubescens. ...
... B. rubescens is a canopy species belonging to Moraceae family (Berg 1972) that can reach 90 cm diameter at breast height with heights of up to 35 m (Laurance et al. 2004). In Brazil, the occurrence of this species is reported in forests in the Amazonia, Fig. 1 Geographic distribution of spatial records and Kernel density estimation (KDE) of Brosimum rubescens B. rubescens in tropical South America, with higher values of density (red) associated with zones with higher frequency and intensity of collection Cerrado, and Atlantic Forest biomes, with spatial interruptions coinciding with the Caatinga Biome and monodominant forests registered only in Amazonia-Cerrado transition zone (Marimon et al. 2001(Marimon et al. , 2014a(Marimon et al. , 2020. In Amazonia and Atlantic Forest biomes the soils are dystrophic but shallow for the former and humid and deep for the latter (Quesada et al. 2010;Joly et al. 2012). ...
Brosimum rubescens, a tree species with Neotropical distribution, can achieve local monodominance in Southern Amazonian forests. Understanding how and why this species varies across space and time is important because the monodominance of some species alters ecosystem complexity. Here we evaluated the fundamental ecological niche of B. rubescens by species distribution models (SDM), combining predictive environmental variables with occurrence points, and determined the temporal persistence and how the spatial distribution patterns of this species vary with different environmental predictive variables. To generate the SDMs, we incorporated predictive environmental variables as main components of climatic, hydric and edaphic variables. All algorithms showed higher performance in spatial predictions for hydric variables and for the combination of climatic, hydric and edaphic variables. We identified that the potential niches of B. rubescens seem to be defined by climatic fluctuations, with the edaphic conditions not limiting the presence of this species in the evaluated spatial scale. From the last glacial maximum to the present, this species seems to have increased its spatial amplitude; however, from the present to the future, predictions suggest that B. rubescens will experience a considerable loss of its range. Our findings showed independent and combined effects of different environmental variables, allowing us to identify which are limiting or facilitating the spatial distribution of B. rubescens. We corroborate the spatial persistence and geographical fidelity of the species’ distribution patterns over time.
Graphical abstract
... Hence, savanna and forest formations of the Cerrado-Amazonia transition provide a good opportunity to investigate how species from different vegetation types respond to limiting access to water. These species are under the influence of pronounced climate seasonality, high temperatures, and marked variations in humidity, which can trigger a water deficit gradient during the year (Marimon et al., 2020;Peixoto et al., 2018;Reis et al., 2018). In this highly seasonal region, Ψ l regulation may be a distinct trait reflecting ecological strategies across species in different vegetation types. ...
... The climate is Aw, according to Köppen's classification (Kottek et al., 2006), with well-defined wet (October-March) and dry (April-September) seasons. Between Between 1997 and 2019, this region also presented a general trend of markedly increasing temperature and declining precipitation, with more negative maximum cumulative water deficit values (Marimon et al., 2020). ...
... At the global scale, increases in extreme climate events (Franklin et al., 2007;Marimon et al., 2020), pest and disease outbreaks, alien species invasions (Dyderski & Jagodziński, 2020), and anthropogenic activity (Barlow et al., 2016;Gomes et al., 2019) have damaged forest ecosystems, leading to biodiversity loss and widespread concern. Trees are the primary constituents of forests and thus the most relevant biodiversity measure at the stand scale (i.e., alpha diversity) (Lähde et al., 1999;Valbuena et al., 2012;Feroz et al., 2016). ...
Natural forests comprise trees of different species and sizes, constituting a "biotic framework". Although examinations of diversity patterns at various spatial scales are frequently conducted, life stages are rarely accounted for. Pine-oak mixedwood forest is widely distributed around the world and constitutes main forest type in the Nanpan River Basin in southwest China. We established a fixed plot with an area of 100 m × 100 m in an undisturbed forest stand and classified trees according to five life stages based on their diameter at breast height (DBH) and height. Then, we calculated eight traditional diversity indices for each life stage. We found that species richness (R), abundance (N), and three diversity indices first increased and then decreased with increasing life stage. As sampling area increased, R, the Shannon-Wiener index (H') and Simpson's diversity index (D) first increased quickly, followed by a reduced rate of increase, whereas N showed a linear increase and three evenness indices showed gradual decreases. Global Moran's I values for each diversity index were small, indicating weak spatial autocorrelation. Both R and N of shrubs and saplings decreased sharply with life stage, with only large trees comprising the later life stages. Our results indicate that species diversity patterns in pine-oak forests, particularly in early successional stages, differ among life stages. The changes contribute to the understanding and conservation of forest biodiversity.
... Tree populations in the Amazon-Cerrado transition are mostly composed of species with a short life cycle ("hyperdynamic", Marimon et al., 2014) but have also recently experienced net declines in abundances due to land-use change and extreme climate events (e.g. Nogueira et al., 2019;Marimon et al., 2020). How they regenerate will be a critical factor in determining the ecological stability of a large area of forest in central South America. ...
In central Brazil, there are strong gradients and discontinuities in vegetation structure and composition between the forests of southern Amazonia and the open savannas of South America's Cerrado. These transitions are often controlled by disturbance processes, and the ability of vegetation to respond to climatic and environmental changes may depend on the regeneration traits of the different floras present. In this study we aim to assess the regeneration traits of tree communities of the Amazon-Cerrado transition and to understand how they differ among and within the markedly different vegetation types. We sampled 39 one-hectare long-term monitoring plots that include typical cerrado (TC = 10), cerradão (CD = 3), gallery forests (GF = 3), floodplain forests (FF = 6), seasonal and open rainforests (SF = 17). The regeneration traits assessed included dispersal syndrome (zoochory, anemochory, and autochory), fruit consistency (dry and fleshy), number of seeds per fruit, and diaspore dimensions (width and length). We found differences among the vegetation types, in all regeneration traits. These tended to be aggregate by vegetation structure, being similar for cerrado and cerradão species, and similar for SF, FF and GF (more forested vegetation). Vegetation types did not differ in functional diversity, however, while regeneration traits among seasonal and open rainforests were well-dispersed, in floodplain forests they were more clustered. Tree species depend substantially on fauna (zoochoric species between 42 and 86% in vegetation) for the dispersal across all habitats. By considering regeneration traits in the study of tree recruitment and establishment, we will increase our understanding about the dynamics of tree communities in neotropical forests and savannas.
... To date, there have been no studies that have made this association in plants of Amazonian savannas. Nevertheless, we assume that the occurrence of ducts and cavities in the studied species is an adaptation mechanism, since the evolutionary history of these areas is marked by climate conditions that, in the past, were drier and more favourable to Cerrado vegetation (Ab' Saber, 2003) and which currently suffer intense cycles of water scarcity (see Marimon et al., 2020;Sullivan et al., 2020). Besides, other factors, such as biogeography, phylogenetic events, external lesions, exposure to pathogens, insect attack and extreme temperatures, could explain the existence of ducts and cavities in different plant groups, apart from those constitutively formed (Fahn 1979;Lange 2015). ...
• This study represents an important contribution to the structural, histochemical and biological understanding of ducts and cavities in leaves of four species of Calophyllaceae that occur in Amazonian savannas.
• Samples of adult leaves were processed using light, scanning and transmission electron microscopy, as per usual methods for plant anatomy.
• In paradermal sections, the lumina of ducts are elongated while those of cavities are short. Ducts occur exclusively in the central rib and are abundant in Kielmeyera rubriflora Cambess and Kielmeyera coriacea Mart. and Zucc and larger than in Calophyllum brasiliense Cambess and Caraipa densifolia Mart. In mesophyll, the type of secretory structure and distribution pattern of the ducts and cavities are distinct. In most species, the secreted metabolites are similar and consist of phenolic compounds, lipids, essential oils with oleoresins, mucilage, neutral polysaccharides, proteins and alkaloids, except in K. coriacea, which does not contain oleoresin. The secretion is probably synthesized by mitochondria, rough endoplasmic reticulum, ribosomes and dictyosomes and is externalized toward the lumen by granulocrine and eccrine processes.
• In addition to being of diagnostic value for species identification, the attributes of the lumen shape, type of secretory structure, distribution pattern, identified metabolites and secretion mechanism are important for understanding the biological roles of ducts and cavities. The identified metabolites reveal a capacity for adaptation, resistance and protection from the action of herbivores and pathogens, and in water retention.
... A possible driver of the increase in liana infestation may be that lianas tend to favor dry conditions and exhibit a dry season growth advantage over trees [57]. Whilst Borneo has one of the most aseasonal climates of any tropical region [41] (Whitmore 1984), recent evidence has suggested that Borneo may be experiencing hotter and drier conditions driven by continued deforestation [42,59,60], which is likely to provide favorable conditions for liana growth [57,61]. ...
Lianas (woody vines) play a key role in tropical forest dynamics because of their strong influence on tree growth, mortality and regeneration. Assessing liana infestation over large areas is critical to understand the factors that drive their spatial distribution and to monitor change over time. However, it currently remains unclear whether satellite-based imagery can be used to detect liana infestation across closed-canopy forests and therefore if satellite-observed changes in liana infestation can be detected over time and in response to climatic conditions. Here, we aim to determine the efficacy of satellite-based remote sensing for the detection of spatial and temporal patterns of liana infestation across a primary and selectively logged aseasonal forest in Sabah, Borneo. We used predicted liana infestation derived from airborne hyperspectral data to train a neural network classification for prediction across four Sentinel-2 satellite-based images from 2016 to 2019. Our results showed that liana infestation was positively related to an increase in Greenness Index (GI), a simple metric relating to the amount of photosynthetically active green leaves. Furthermore, this relationship was observed in different forest types and during (2016), as well as after (2017–2019), an El Niño-induced drought. Using a neural network classification, we assessed liana infestation over time and showed an increase in the percentage of severely (>75%) liana infested pixels from 12.9% ± 0.63 (95% CI) in 2016 to 17.3% ± 2 in 2019. This implies that reports of increasing liana abundance may be more wide-spread than currently assumed. This is the first study to show that liana infestation can be accurately detected across closed-canopy tropical forests using satellite-based imagery. Furthermore, the detection of liana infestation during both dry and wet years and across forest types suggests this method should be broadly applicable across tropical forests. This work therefore advances our ability to explore the drivers responsible for patterns of liana infestation at multiple spatial and temporal scales and to quantify liana-induced impacts on carbon dynamics in tropical forests globally.
... También se observa en una alta frecuencia de T. altissima, E. precatoria e I. deltoidea en todos los bloques, esto se debe a una disposición suficiente de agua y nutrientes que, sumado a un incremento de luz, debido a talas modificaron el dosel y así promovieron el crecimiento y reclutamiento de individuos de palmeras y arboles rápido medianos (Sousa et al., 2020). Por otra parte, la Figura 4 muestra que la diversidad de árboles recupera su exuberancia, con especies impacta-das por la tala como B. lactescens y C. racemosa, que vieron limitado el reclutamiento de nuevos individuos, esto modifica profundamente su abundancia y frecuencia en los bloques (Marimon et al., 2020). La presencia de una gran diversidad de géneros como Aniba, Ocotea, Quiina, Aspidorsperma, Dypterix, Clarisia y Virola, distribuida de forma heterogénea. ...
The Amazonian forests of Peru are among the most diverse and disturbed by anthropic activities on the planet, today there are still gaps on the composition of the communities and their inter-specific relationships. A forest inventory was carried out in a terraced forest in the Madre de Dios region, 5 blocks were established with 2 rectangular plots of 20m x 500m each to identify and measure individuals with diameter greater than 10 cm. 4429 trees were evaluated and 254 species, 165 genera and 53 families were identified. The distribution of diameter classes and height presents typical patterns of intervened forests, in this case by the extraction of wood decades ago. The average of the biodiversity indices are: Shannon-Wienner 4.039 ± 0.16 and α-Fisher 39.90 ± 9.23, indicating that there is a high diversity of species. The species of greatest ecological importance were: Tetragastris altissima (Aubl.) Swart, Iriartea deltoidea Ruiz & Pav, Euterpe precatoria Mart., Which are fast growing and are present throughout the neo-tropics, Tachigali vasquezii Pipoly, abundant only in the forests of this region; These species took advantage of the opening of the canopy by felling and increased their abundance and dominance in the area. On the other hand, Ocotea bofo Kunth, Bertholletia excelsa Bonpl, Eschweilera coriácea (DC.) S.A. Mori, dominate the forest, but of low abundance, due to changes in the floristic composition after wood harvesting.
... The temporal and spatial maintenance of B. rubescens monodominant forests is linked to episodic recruitment in response to climatic interference, mainly associated with the impacts of prolonged drought disturbances Despite the morpho-anatomical and physiological attributes and environmental adaptations of B. rubescens, these drought events have caused a drastic reduction in regeneration, which may contribute to its population decline, monodominant and mixed, in the Amazonia-Cerrado transition (Marimon et al. 2012(Marimon et al. , 2020. In this sense, future climatic variations may affect the sensitive balance between mortality and recruitment, affecting the local and regional distribution of B. rubescens. ...
... Drought is an important factor related to the hyperdynamisms of tropical forests, affecting the structure, dynamics, and composition of tree species (Marimon et al. 2012). The regeneration of this species may be conditioned by decreases in the availability of water derived from droughts during and after ENSO events (Marimon et al. 2020). However, B. rubescens also produce larger amounts of seeds during drought periods (Marimon and Fel li 2006), and this strategy may be advantageous for maintaining its dominance The environmental suitability matrices obtained from the CEH-1 scenario were adjusted to the spatial patterns of occurrence reported for B. rubescens within the study area. ...
... In the Neotropics, B. rubescens are spatially discontinuous, but the highest frequency of records is associated with the Amazon Basin in Brazil, Peru, Colombia, and Guianas (Berg 1972). In the Brazilian Amazonia-Cerrado transition, B. rubescens form extensive monodominant forests (Marimon et al. 2001(Marimon et al. , 2020. In central Amazonia, this species had greater spatial connectivity in the environmental suitability. ...
Aims Brosimum rubescens, a tree species with a Neotropical distribution, can achieve local monodominance in Southern Amazonia forests. Understanding how and why this species varies across space and time is important because the monodominance of some species alters ecosystems complexity. Here we evaluate the fundamental ecological niche of B. rubescens by species distribution models (SDM), combining predictive environmental variables with occurrence points. We specifically aim to 1) determine how the spatial distribution patterns of B. rubescens vary with different environmental predictive variables, and 2) evaluate the temporal and spatial persistence of B. rubescens in the Neotropics. Methods
To generate the SDMs, the predictive environmental variables were incorporated as main components of climatic, hydric and soil variables. ResultsAll algorithms show higher performance in spatial predictions for hydric variables and for the combination of climatic, hydric and edaphic variables. We identified that the potential niches of B. rubescens seem to be defined by climatic fluctuations, with the edaphic conditions being predictive variables that are not restrictive of their presence on the evaluated spatial scale. From the LMG (Last Glacial Maximum) to the present, the species seems to have increased its spatial amplitude; however, from the present to the future, predictions suggest that B. rubescens will experience a considerable loss of its range. Conclusions
Our findings show the independent and combined effects of different environmental variables, allowing us to identify which limit or facilitate the spatial distribution of B. rubescens . We corroborate the spatial persistence and geographical fidelity of the species' spatial patterns over time.
