"Megaherbivores act as the 'gardeners' of humid tropical forests: They are vital to forest regeneration and maintain its structure and biodiversity", as was explained to SINC by Ahimsa Campos-Arceiz, the lead author of the study that was published in the 'Biotropica' journal and researcher at the School of Geography of the University of Nottingham in Malaysia.
In these forests in East Asia, the large diversity of plant species means that there is not enough space for all the trees to germinate and grow. As well as the scarce light, seed dispersion is made more complicated by the lack of wind due to the trees that are up to 90 metres high. Plant life is then limited to seeds dispersed by those animals that eat pulp. They either scatter seeds by dropping their food, regurgitating it or by defecating later on.
In the case of large seeds, "plants need a large animal capable of eating, transporting and defecating the seeds in good conditions," as outlined to SINC by Luis Santamaría, co-author and researcher at the Mediterranean Institute for Advanced Studies (IMEDEA) of Spain's CSIC Scientific Research Agency. This is where elephants and rhinoceroses come into play because they can scatter large quantities of seeds thanks to the fact that they slowly digest very little of their food.
However, habitat loss, poaching, and the conflict between elephant and man has caused a 95% loss in Asian elephant (Elephas maximus) historical distribution range and has left the rhinoceros just a step away from extinction: there are less than 50 Java rhinoceroses (Rhinoceros sondaicus) and 200 Sumatra rhinoceroses (Dicerorhinus sumatrensis).
According to the red list of the International Union for Conservation of Nature (IUCN), elephants are in 'danger of extinction' and the two rhinoceros species are 'critically endangered'.Asian tapirs are no elephants
The study allowed researchers to analyse the effect of dispersion by tapirs on the seed survival of nine different plants. This included some large plant species such as the mango tree and durian, as well as other smaller species like the 'elephant apple' (Dillenia indica).
Among other outcomes, the results show that tapirs defecated 8% of the tamarind seeds ingested (none of which germinated) compared to elephants, who defecated 75% of the 2,390 ingested seeds (65% of which germinated).
"The Asian tapirs spit, chew or digest the majority of large seeds. This either destroys them or leaves them in the same place. As a result, they are not good dispersers for plants with large fruits and seeds," confirms Campos-Arceiz. In this sense, "given the role that they play they belong to a different group to elephants and rhinoceroses."Stopping illegal hunting is the priority
Without large herbivores, new large seed plants will always grow in close proximity to the mother plant and are therefore "unable to colonise available space in other forest areas," warns the IMEDEA researcher.
In this respect, those species that depend on large animals will become increasingly rare whereas those that depend on the wind and smaller, abundant animals will increase in terms of density and dominance. Campos-Arceiz asserts that "at the end of the day, the composition and structure of the forest changes and ends up becoming less complex on a structural and functional level: this translates as a loss of biodiversity."
To avoid such a scenario, researchers suggest that megafauna should be protected and in some cases megaherbivores should be reintroduced into areas from where they had previously disappeared. "In the south-east of Asia, the priority is to stop illegal hunting and mitigate the impact of habitat loss," indicates the expert, criticising the "absurd" motivation to kill in order to sell their horns and tusks for traditional medicine ("with no therapeutic benefits") or to make ornamental products. This also highlights the need to combat illegal trade in a "much more determined way."Reference
SINC Team | EurekAlert!
Treatment of saline wastewater during algae utilization
14.05.2019 | Jacobs University Bremen gGmbH
Plastic gets a do-over: Breakthrough discovery recycles plastic from the inside out
07.05.2019 | DOE/Lawrence Berkeley National Laboratory
A new assessment of NASA's record of global temperatures revealed that the agency's estimate of Earth's long-term temperature rise in recent decades is accurate to within less than a tenth of a degree Fahrenheit, providing confidence that past and future research is correctly capturing rising surface temperatures.
The most complete assessment ever of statistical uncertainty within the GISS Surface Temperature Analysis (GISTEMP) data product shows that the annual values...
Physicists at the University of Basel are able to show for the first time how a single electron looks in an artificial atom. A newly developed method enables them to show the probability of an electron being present in a space. This allows improved control of electron spins, which could serve as the smallest information unit in a future quantum computer. The experiments were published in Physical Review Letters and the related theory in Physical Review B.
The spin of an electron is a promising candidate for use as the smallest information unit (qubit) of a quantum computer. Controlling and switching this spin or...
Engineers at the University of Tokyo continually pioneer new ways to improve battery technology. Professor Atsuo Yamada and his team recently developed a...
With a quantum coprocessor in the cloud, physicists from Innsbruck, Austria, open the door to the simulation of previously unsolvable problems in chemistry, materials research or high-energy physics. The research groups led by Rainer Blatt and Peter Zoller report in the journal Nature how they simulated particle physics phenomena on 20 quantum bits and how the quantum simulator self-verified the result for the first time.
Many scientists are currently working on investigating how quantum advantage can be exploited on hardware already available today. Three years ago, physicists...
'Quantum technologies' utilise the unique phenomena of quantum superposition and entanglement to encode and process information, with potentially profound benefits to a wide range of information technologies from communications to sensing and computing.
However a major challenge in developing these technologies is that the quantum phenomena are very fragile, and only a handful of physical systems have been...
29.04.2019 | Event News
17.04.2019 | Event News
15.04.2019 | Event News
24.05.2019 | Physics and Astronomy
24.05.2019 | Medical Engineering
24.05.2019 | Life Sciences