Demographic structure of a threatened palm (Euterpe edulis Mart.) in a fragmented landscape of Atlantic Forest in northeastern Brazil

Abstract

At the northern limits of the range of the palm species Euterpe edulis there is an endemic ecotype, known as the "Bahia" ecotype, which is distinguished by its reddish crownshaft and low seed production. Unfortunately, little is known about its demographic characteristics. Therefore, we contrasted the density of E. edulis populations in the Una region, in the southern part of the Bahia state, Brazil, with that of other populations of the species in southern and southeastern Brazil. In addition, within the Una region, we compared a long-protected forest fragment (F1) with three recently protected fragments (F2, F3, and F4), in terms of demographic parameters and plant size, in order to determine what influence, if any, time since protection has on E. edulis populations. Population densities within the Una region were higher than in regions where E. edulis populations are stressed by harvesting or intense seed predation but much lower than in regions with well protected populations. Among the Una fragments, density was highest in F1 and lowest in F2. The proportion of individuals at the various developmental stages differed among the fragments (χ²=25.219, df=12, p=0.014). Diameter at ground level, height, and number of leaves correlated positively among themselves and negatively with population density. For all developmental stages, F1 surpassed the other fragments in terms of densities and plant sizes. It is likely that the newly protected populations suffer the lingering effects of previous harvesting, which are reflected in their demography and in the size of their individual members. The viability of this low-density endemic ecotype must be established in order to assess the conservation status of the species on a regional scale.

Demographic processes limit upward altitudinal range expansion in a threatened tropical palm

“…), with a higher density. We assumed that the local environmental conditions at the lower-altitude site were optimal for E. edulis, since the population density we recorded was the highest ever documented for this species (54,320 ind/ha), when compared to previous studies (Melito, Faria, Amorim, & Cazetta, 2014).…”

Population modelling and genetics of a critically endangered Madagascan palm Tahina spectabilis

“…Given this life cycle, small populations of adults can potentially be lost if plants reproduce too infrequently or if the resulting seed crop is aborted or destroyed by predation as the species depends of successful regeneration of seedlings. Palms play a particularly important role in human lives in poorer countries, such as Madagascar; however, they are often destructively harvested, for example, for palm heart consumption or construction materials, and in the case of T. spectabilis , that would lead to loss of reproductive potential as well as adult population size (Gruca, Blanch‐Overgaard, Dransfield, & Balslev, 2016; Melito, Faria, Amorim, & Cazetta, 2014; Rakotoarinivo et al, 2014; Shapcott, Quinn, Rakotoarinivo, & Dransfield, 2012).…”

“…Some local measures have been put in place at the original locations first visited in 2008 to protect T. spectabilis from fire and cattle trampling, considered to be threats to this species in situ (Gardiner, Rabehevitra, Letsara, et al, 2017; Gardiner, Rabehevitra, & Rajaonilaza, 2017). Demographic population modelling approaches have been widely used in palm studies to predict the impacts of differing threats on species including fire, grazing and harvesting and have proven a useful tool for conservation management (Arneaud et al, 2017; Gamba‐Trimiño, Bernal, & Bittner, 2011; Mandle & Ticktin, 2012; Martínez‐Ballesté, Martorell, Martínez‐Ramos, & Caballero, 2005; Melito et al, 2014; Navarro, Galeano, & Bernal, 2011; Pinéro, Martinez‐Ramos, & Sarukhan, 1984). The application of these approaches to investigate T. spectabilis population growth is likely to provide insights into its long‐term viability.…”

“…Demographic population modelling approaches have been widely used in palm studies to predict the impacts of differing threats on species including fire, grazing and harvesting and have proven a useful tool for conservation management (Arneaud et al, 2017;Gamba-Trimiño, Bernal, & Bittner, 2011;Mandle & Ticktin, 2012;Martínez-Ballesté, Martorell, Martínez-Ramos, & Caballero, 2005;Melito et al, 2014;Navarro, Galeano, & Bernal, 2011;Pinéro, Martinez-Ramos, & Sarukhan, 1984). The application of these approaches to investigate T. spectabilis population growth is likely to provide insights into its long-term viability.…”

The risks of introduction of the Amazonian palm Euterpe oleracea in the Atlantic rainforest

“…(Arecaceae) -a native species from the Atlantic Forest -has been legally protected (Silva Matos and Bovi, 2002;Galetti and Fernandez, 1998). However, the over-exploitation of E. edulis, has contributed significantly to changes in its populations structure leading this species to extinction in several forest fragments (Melito et al, 2014;Silva Matos and Bovi, 2002). To guarantee the continuous production of palm heart, several species have been introduced in this ecosystem.…”