Inclusive Understanding of Nypa Fruticans Wurmb as an Invasive Mangrove in West and Central Africa

Mangroves have been widely described and known as a group of salt-tolerant pantropical trees or shrubs species thriving in intertidal zones between dry land and open sea. Several remarkable studies have been evolved in mangrove flora ecology and its function, disturbances and modelling dynamics [1], rebuilding mangrove resilience through community efforts [2]. And mitigate fuel wood used by improved smoke house [3], as well as its environmental and socio-economical fallouts. However, little and or inadequate attention has been paid on to check why Nypa fruticans along mangrove of West and central Africa, and the world in General. In this light, the short communication provide additional invasive trait information, which will assist eco-physiologist, botanist, and others to undertake practical mangrove conservation work.

Mapping and understanding of which Nypa traits lead to the different levels of invasion and impacts are at the heart of prioritizing Nypa invasion for control and management. There is a range of intrinsic and extrinsic traits considered actually important intermediaries of the success of Nypa palms invasion. In summary observed key traits of Nypa palms can include:

Bio-geographical traits. Nypa palm performance in other places where it was introduced intentionally or not may be useful in forecasting Nypa invasion potential. Different sites have been invaded and were hotspots just like in the Panama and southern Caribbean Islands [4] and the Niger Delta, Nigeria [5,6].

So previous local and regional history may be among the traits. The results of this study, in combination with these Authors, Liu J, et al. [7], suggested that anatomical and physiological adaptations confirmed Nypa invasiveness traits. The mangrove area across these invaded sites provided some clues of the climatic suitability of the introduced range of Nypa. Mangroves native to one part of the Asia-Pacific environment were likely to have become invasive elsewhere with similar mangrove climatic conditions.

Vegetative traits associated with ecological impacts. Demographic processes, and traits there associated, link to invasion rates and plant abundance, which ultimately influence plant impacts at community and ecosystem scales. This study also confirms that Nypa is an upright stem species that produces new (i.e. sprouting) individual palm from a prolific dichotomously rhizome while flowering and fruiting at the same time on the erect inflorescence. This study further confirms that Nypa is a pleonanthic palm [8]. Fronds used for thatches lifespan was less than seven months. Cutting and burning or forage of the fronds do not kill the palm rather allow residue fronds (1/3 petiole) to hasten other spear frond production and reinforces the individual palm soil adherence and resistance to wind. Hence, the timing of frond out and of frond loss does not influence belowground but aboveground biomasses. The palms harbours more below ground biomasses and other nutrients compared to native species. This trait showed that Nypa with short life fronds span, carries out photosynthesis rapidly and stores a greater quantity of carbohydrates in its rhizome for growth adaptation to stress or not. With such adaptation [9], other Nypa invasiveness traits can be predator avoidance and/or deterrence due to hiding rhizomes that produce new individual palms which phenotype are identical to the parent palm. Mortality was rare once the palms had bypassed the seedlings stage. Chop fire or Nypa palm with its slenderness has intrusive moderate impacts in mangrove stands understory and gaps (i.e. under different shade conditions, over story branch die-back, breakage, or fallen trees) as they growth swiftly dispersed and accidentally clustered into pure stands of more than 3000 individuals per ha. Hence, a classification code for Nypa invasion presence and ecological state has been proposed based on their demographic traits. Henceforth, the scenario data can easily state, capture and monitored Nypa’s presence or absence following mangrove management options. These codes make a record of every site or stand’s invaded state and attributing to a particular class of distribution pattern (Capital or upper case letter) and colour (small or lower case letter), all depicting Nypa palms densities. Nypa is a shade tolerant, look as generalist species showing a widespread and occurrence on range of soil and water intra- and inter-specific interrelations, and can seedlings used adapted feature (plumular) to compete for nutrients just as the native mangrove species. Hence, many sites have become hotspots and the likelihood ratio (8.38) to see more Nypa in all regimes after 12 years. In that light, Nypa showed long-term occupancy following its spread and subsequent pure stands establishment. This species is on the ‘impacts’ list of the Cameroon Invasive Plant list surely because of the recognition of its steady spread.

High seed production, good seed viability and time of year of fruiting. Nypa produces continues a tremendous amount of viable seeds [10] annually because fruiting was highly asynchronous and lasted for seven months. It might be difficult to check asynchronous fruiting production yearly on a landscape; however, early control efforts of the set fruiting head in the months of September to early January may reduce seed production. Only half of the drifted seeds were dispersed rapidly, break dormancy while floating or at rest due to scourging seawater, soil and climate conditions. The anatomical and morphological adaptations showed that not all seed with oblong or spherical that abscised from the parent plant (peduncle) germinate directly; delayed may occurs and so some seed may outgrow later time when environmental conditions are right. More traits for Nypa include acquisition of desiccation tolerance and good seed longevity due to seed cavity, egg-shaped and coats seed and its transient seed banks (soil and water) nature. A Nypa seedling undergoes the sit-and-wait to evade environmental filters. Vectors. Gravity, water and/or animals disperse Nypa seed. For most invasive plants to be naturally successful at invading into new areas, they must rely on a vector (i.e. carrier or transporting agent). A Nypa nonorthodox seed uses an effective dispersal mechanism that includes gravity (barochory-primary dispersal), water (hydrochoric-secondary dispersal) and humans (anthropochory-tertiary dispersal). The vector trait characterizes the most successful of invasive plant species. Nypa sexual reproduction breeding system. Nypa is a monoecious palm [11,12], therefore, as Nypa palm expressing a monoecious breeding system only need a single plant or seedling to start an invasion in intertidal zone. This is one of the major reasons why unmanaged Nypa palms are so successful at rapidly colonizing intertidal mangroves. When mangroves landscapes support such populations for decades it becomes very costly to control them, especially to reduce the population by 90%. Possible antagonist coevolution trends may be observed between Nypa and native species in such a case. The seedling cohort’s germinability was synchronously moderate with some mortality. Seedlings produced plumular that served as shield and first photosynthesis organ, and growth under any density and shade conditions. Seedlings produced fronds rapidly and in an increased manner while maintaining seed’s utmost coat integrity for a period. Hence, to undertake Nypa invasion control projects, there is need to be aware of its breeding system and growth morphological adaptations and at what point in its life cycle it produces flowers and seeds.

Extrinsic factors. Nypa incursion has undergone through all invasion stages outlines by some authors [13-17]. Ecological niche according to Hutchinson (1957) can be observed for chop fire palms across Cameroon estuaries. Factors that favoured such invasion included to the organic matter, brackish water, photosynthesis (photosynthetic assimilation), sedimentation, land use and topography, and frond and rhizome residues, seeds pressure due to the combination of traits and proximity to Nypa sources, seed banks, and tidal regimes [18]. Mangrove ecosystem regime/disturbance (natural and overexploitation of the Rhizophoraceae) and residence time since invasion. Absence of predators may also be an added factor to Nypa invasion. Human interference and mangrove stands predisposition (land and sea interplay) certainly set an opposite hydrohalophyte sociological connexion of Nypa to pure, R. racemosa or mixed stands. These co-operating legacies yielded an invasion debt [13].

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