A hidden food web found in the desert that “thrives on death”!

Harsh conditions make it difficult for plants to grow, which means that every leaf is valuable, even if it is dead and rotting.

A new study from the Bulkumatta Wildlife Sanctuary in South Australia has demonstrated the importance of plant remains in maintaining the desert ecosystem and has revealed an alliance between termites and dingoes.

“Much of the research on dryland ecosystems has been focused on green food webs that follow ‘boom periods’ triggered by events like heavy rains,” says Mike Letnick, a conservation biologist at the University of New South Wales (UNSW). desert flora and an increase in the population of many plant-eating animal species such as herbivores and rodents.

But dry times are important because they dominate the existence of life in arid environments.

In this remote study, the researchers compared areas where large herbivores like kangaroos and goats lived freely with one-hectare fenced enclosures where voracious plants didn’t gnaw.

In doing so, UNSW ecologist and lead author Baptiste Vigas and colleagues were able to identify the impact of large herbivores on brown food webs, in which the main food source is decaying plants rather than living plants. Decaying plant tissue is converted into food energy for the rest of the web when insects such as termites and worms consume it, food for small vertebrates.

Brown webs are found in most habitats, but their influence can be more pronounced in areas with fewer resources, such as drylands and deserts.

“We found that a decrease in dead biomass due to overgrazing by herbivores can lead to a decrease in termites,” explains Vegas. “And a decrease in termites, the main decomposers in these environments, can ultimately lead to a decrease in lizards and small mammals.” “. in arid ecosystems, where many of these small vertebrates feed on termites.

These findings contrast with studies done in more fertile regions, where growing herbaceous plants actually pumps up the brown food web and speeds up nitrogen cycling.

However, in the desert, because there is already so little vegetation, the herbivores eat a lot of the vegetation, which means that there is not enough leftover vegetation to become dead insect-eating plants.

This results in fewer lizards and smaller escaping mammals such as dunnarts, small marsupials found in Australia that prey on predators, and less food for larger animals such as vultures and snakes.

It has long been established that kangaroos abound throughout arid Australia. This problem has arisen, at least in part, because a crucial component of both green and brown food webs is missing from the equation: the top predator.

Humans have driven dingoes from much of the wasteland to protect grazing sheep, and have even gone so far as to build a huge 5,600 kilometers (3,490 mi) long fence across southeastern Australia.

Fencing studies have previously shown the extent of the impact that the absence of these top predators can have on vegetation levels.

The removal of dingoes from the native Australian grasslands landscape has given way to heavily overgrown forest scrub. They provide a hiding place from which wild cats and foxes can swoop in and devour endangered local marsupials unhindered. Overgrazing has changed the shape of the dunes, and the difference in vegetation can even be seen from space.

While more work is needed to confirm the results because the study plot sizes were small and the team did not directly link termite abundance to vertebrate populations, the new results complement growing research showing how different species in ecosystems depend on each other. those that seem unrelated to each other, such as dingoes and termites.

This study is published in Ecosystems.

Source: Science Alert