"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!
Waste in the water – New purification techniques for healthier aquatic ecosystems
24.07.2018 | Eberhard Karls Universität Tübingen
Plenty of habitat for bears in Europe
24.07.2018 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig
There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.
The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
17.08.2018 | Event News
08.08.2018 | Event News
27.07.2018 | Event News
21.08.2018 | Power and Electrical Engineering
21.08.2018 | Life Sciences
21.08.2018 | Medical Engineering