Copernicia tectorum is a palm that grows in large populations on seasonally flooded savannas in the ]]>
Copernicia tectorum has the fastest leaf production rate recorded for any palm (19-23 leaves/year in subadults and adults), and a short life span of ca. 46 years. The abundance, density and high leaf production rate of this palm offer a great potential for the sustainable use of its unexpanded leaves (especially at Plato, where there are ca. 480ha of palm stands with 300-1 000 individuals/ha), as ]]>
La palma Copernicia tectorum forma grandes poblaciones en sabanas estacionalmente inundables de la región Caribe de Colombia, ]]>
Copernicia tectorum tiene la tasa de producción de hojas más rápida registrada hasta ahora para cualquier palma (19-23 hojas por año en subadultos y adultos) y una vida corta de ca. 46 años. La abundancia, densidad y alta tasa de producción de hojas de la ]]>
Palabras clave: Depresión Momposina, estructura poblacional, impacto de la cosecha, plantas ]]>
Fibers obtained from wild palms play a significant role in Colombian handicraft production (Linares, Galeano, García, & Figueroa, 2008). One of the most important fiber-producing palms in the Caribbean lowlands is the sará palm, Copernicia tectorum (Kunth) Mart., which grows only in dry savannas in Northern Colombia and Venezuela, where it forms extensive stands in areas that are subject to severe drought during the dry season, and to permanent flooding during the rainy season (Troth, 1987; Galeano, & Bernal, 2010). In some lagoon complexes at the Mompox Depression, in Northern Colombia, this species is the dominant element in the vegetation. In these areas the palm has a major ecological role, due both to its abundance and to the numerous ]]>
The sará palm also has a great importance to local communities, as its leaves and stems are used in construction, and fiber obtained from its unexpanded leaves is the base of a flourishing handicraft activity of local importance. In the ]]>
Extraction of non-timber forest products (NTFPs) has been the subject of a long debate as to the scope and extent of the research that is required to guarantee sustainability (Peters, 1996; Wong, Thornber, & Baker, 2001; Ticktin, 2004). There seems to be a consensus, however, about the need of basic biological and ecological studies, as a starting point to plan sustainable management, even for those species that have been traditionally used. ]]>
In this paper we used data on abundance, density, and size class distribution and plant growth, to assess the state of populations of Copernicia ]]>
under various harvest regimes at three localities in the Mompox Depression, in the Caribbean region of Colombia. We also present data on the impact of river floods on the populations, and describe a plausible scenario of changes in the palm stands in the long run.
Materials and methods
Study site: We studied populations of C. tectorum around Ciénaga Zárate, and Ciénaga Cascaloa, a complex of lagoons in the floodlands of the lower Magdalena river, near the towns of Plato and Magangué, in the departments of Magdalena and Bolívar, in Northern Colombia. This area is part of the Mompox Depression (Depresión Momposina), Colombia’s ]]>
Study species:Copernicia tectorum is a solitary palm with an erect stem 5-10m tall, 20-30cm in diameter, which remains covered for some time with persistent leaf bases (Galeano, & Bernal, 2010). It has a mass of adventitious roots at the base, which have been considered as an adaptation to whithstand the long floods (Throth 1987). The crown has 15-25 palmate, circular leaves composed of numerous rigid segments up to 1 m long, with up to 1.6 m long petioles that bear hooked spines along their margins. Inflorescences are interfoliar and project beyond the leaves. They have numerous branches and bear small, hermaphrodite flowers. Fruits are ]]>
Fig. 1).
Sampling: Data were taken at three localities: Plato (Magdalena) and Magangué and Córdoba ]]>
Table 1). We chose sites with a history of use of at least 20 years, in order to be able to detect the effect of harvest on the palm populations. Sites were identified with the help of land owners and harvesters. Five sites were chosen at Plato, where the largest palm populations occur (area >1ha), mostly on common lands. Four of these sites are harvested (Cardonal, Machosolo, Plazoleta, and ]]>
Field work was carried out in ]]>
C. tectorum: stem height (up to the petiole base of the oldest live leaf); diameter at breast height (1.3m) of naked stems; number of leaves; and number ]]>
Table 1). Thirteen months later we counted new leaves produced, and the increase in number of primary veins or segments from one leaf to the next one in 87 palms ]]>
Abundance was estimated using Google Earth images and aerial photographs of the Instituto Geográfico Agustín Codazzi (flight IGAC 2719 of 2004), in which palm crowns of adults and subadults can be recognized. The area of the palm stands at Plato was calculated on the images, and abundance ]]>
For data analysis, we divided the population into seven size classes, based on developmental traits, like ]]>
Table 2) (Galeano et al., 2010). When plotting segment number vs. segment length, we found a change in the slope of the curve at 20 segments (data not shown); because of this, we took >20 segments as the lower limit of the juvenile 2 class. The presence of an aerial stem marks the division of juveniles 2 and juveniles 3, but some stemmed palms have leaves similar to those of juvenile 2; because of this, we chose as the upper limit of the juvenile 2 size class the average number between the highest number of segments of a stemless palm and the lowest number of ]]>
Duration of the ]]>
Fig. 2), and most stems have damages at several places, thus measuring the length of individual internodes throughout the stem is not feasible ]]>
We compared population structure among the three localities Magangué, Córdoba and Plato and among sites at Plato using Kolgomorov-Smirnov (KS) test (Sokal, & Rohlf, 1995). Palm density and leaf production rate were analyzed with the non-parametric Kruskal-Wallis test. When significant ]]>
Results
The area of palm stands at Plato ]]>
Table 3).
The population at Magangué differed from those at Plato and Córdoba in seedlings, juveniles 3, and adults 1; it also differed from populations at Plato in terms of adults 2. Plato and Córdoba differed only in adults 2 (Fig. 3). At Magangué most palms (88%) were juveniles 3, whereas reproductive individuals (1%) and seedlings (4%) were scarce (
Fig. 4A). At Plato and Córdoba there were high proportions of seedlings (65% and 66%, respectively), a decreasing amount of juveniles 1 (8% and 29%, respectively), but few juveniles 2, juveniles 3, and subadults (5.7% and 1.3%, respectively, when pooled). Plato, in turn, had a remarkable proportion of adults 2 (16%) (Fig. 4B), while this class was scarcely represented in Córdoba (1%) and did not occur in Magangué. ]]>
Sites within Plato, including the unharvested one, did not differ among them, except for a difference in adults 2 between Silencio y Machosolo. Only the sites Plazoleta, Cardonal and Silencio had individuals in all size classes. The unharvested population at Ciénaga Cuchillo lacked juveniles 2, juveniles 3, and subadults, and it had scarce juveniles 1 (3%) (Fig. 5).
There was a steady increase in leaf production rate with age, reaching a maximum of 23.4 leaves per year in subadults, and then decreasing to 19 leaves per year in adults (Table 4). It took adult palms about one year to replace their whole crown. There was no strong correlation between initial leaf number and leaf ]]>
Discussion
The similar demographic structure of C. tectorum at Plato and Córdoba, both at harvested and unharvested sites (biased towards old individuals, with abundant ]]>
Leaf production rate (19-23 leaves/yr in subadults and adults) appears to be the fastest one recorded so far for any palm (cf. Henderson, 2002; Bernal & Galeano, 2013), comparable only to that of Hyphaene petersiana (Fanshawe, 1967), another coryphoid palm that grows in similar environments in Africa. Such a fast leaf production rate accounts for ]]>
An apparent cause of death in juveniles was the accumulation on their crown of plants brought by the flood, which got trapped by the petiole thorns, sometimes completely ]]>
Fires taking place during the dry season did not appear to be a relevant cause of death; after the long drought of early 2010, at all of our study sites we found palms with ]]>
Population structure at Plato and Córdoba resembles Peters’s (1996) type III size class distribution, with most individuals of the same age or size, which is common in heliophitic and pioneer plants. Several traits in the life history of C. ]]>
indicate that it is indeed a pioneer of riverine floodlands, as suggested by Troth (1987) for the populations of the Venezuelan savannas. Not only does it thrive in open areas, where it forms dense, monodominant stands, as other riverine pioneers do (cf. Parolin, Oliveira, Piedade, Wittmann, & Junk 2002), but it also has a short establishment phase of only 10.4 years, and its life span (46 years) is one of the shortest recorded for any iteroparous palm (Henderson, 2002). ]]>
As with other pioneer riverine plants, flood dynamics appears to be the most important factor influencing the populations of C. tectorum. First, flood water is known to be the primary dispersal agent of C. ]]>
(Troth, 1987). Additionally, flooding probably increases seedling recruitment, as water soaking favors seed germination, as shown by Kitzke (1958). But, on the other hand, longer and higher floods increase mortality of seedlings (Troth, 1987) and juveniles, as found at our study sites, and it can also cause severe damage to adults through the accumulation of debris and vegetation that get trapped by the recurved petiole spines, and the germination of epiphytes and hemiepiphytes among the leaf bases. ]]>
The palm stands probably play a significant role in regulating river channel dynamics in this inner delta area, where total sedimentation has averaged 3-4 mm/yr over the past 7 500 years (van der Hammen, 1986; Plazas et al., 1988; Kettner, Restrepo, & Syvitski, 2010). This rate is probably higher at the palm stands, as thicker plant stems and larger leaves are known to be effective at capturing particles by reducing water velocity and by providing a surface for sediment adhesion (Brueske, & Barret, 1994; ]]>
Copernicia palms reached 2cm during the period 2010-2011.
As sediments accumulate over decades, inundation in the palm stand will decrease, reducing the favorable conditions described above for palm population growth. ]]>
If Copernicia
tectorum is indeed a pioneer species, with discontinuous and occasional recruitment as a result of river dynamics, the expected population would consist mostly of individuals belonging to just one or two size classes, while at other sites other size classes would be represented. This is exactly what Troth (1967) found in the Venezuelan savannas, where no population had all size classes. Troth pointed the same pattern of stands with individuals of the same size and irregular representation of size classes in other palm species of harsh environments. These include ]]>
Copernicia prunifera from semiarid areas in Northeastern Brazil (Taube, 1952); and Copernicia alba from hyperseasonal savannas in the semiarid Chaco (Puechagut, Politi, Bellis, & Rivera, 2012). ]]>
Population structure at all sites in Plato shows that only well established stands, mostly with adult palms, occur at this site. In fact, at the youngest stand found (Ciénaga Cuchillo, in Plato) average height of individuals was 4.2m, which suggests that the last successful recruitment took place ca. 30 years ago. Considering the palm’s short life span, this stand will probably disappear within the next two or three decades. ]]>
At the palm stands of Plato and Córdoba, abundance, density and leaf production rate offer favorable conditions for leaf harvest for handicraft manufacture. At Magangué, on the contrary, population structure indicates a limited possibility for use, and thus leaf harvest in this area should be regulated, in order to favor recovery of the palm stands. Comparison of harvested and unharvested stands at Plato shows that harvest does not affect population structure if only subadult and adult palms are ]]>
Considering the role of river dynamics on the population fate of Copernicia tectorum, management actions must focus on reestablishing, as much as possible, water flow between the river and the lagoon complexes where the palm grows. This ]]>
The described actions should be ]]>
C. tectorum stands not only offers a good opportunity for integrating use and conservation of this particular species, but may also have a tremendous impact on the decades-long deltaic cycles of floodable vs. terra firme areas. A better understanding of the palm’s ]]>
Acknowledgments
We thank Universidad Nacional de ]]>
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References
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1. Instituto de Ciencias Naturales, Universidad Nacional de Colombia, Apartado 7495, Bogotá, Colombia; mctorresrom@unal.edu.co, gagaleanog@unal.edu.co, rgbernalg@gmail.com
Received 12-VI-2014. Corrected 10-XII-2014. Accepted 19-I-2015.
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