For a long time not many people have considered how plants and animals living in an environment contribute to how a landscape is shaped. Animals living within an area help to sustain the livability of a landscape, diversify the ecology and strengthen the soil structure, all of which help to protect land from increasingly severe weather throughout the world.
Continuing the BES lecture series, Dr. Robert Pringle, an ecologist from Princeton University, spoke about how termites, herbivores and carnivores shape the African savannas. He started the lecture using graphs and satellite imagery to describe how as rainfall decreases in an area, the ecology also decreases until the system completely fails.
“I’m coming at this from the perspective of an animal ecologist. What I’m really interested in is the consumers that influences and shape these systems,” Pringle said
He mainly focuses on the African savannas in central Kenya, large grasslands similar to our great plains. Areas like these in the world have very little tree cover and are at the most risk of turning to desert as the global weather cycle keeps creating longer droughts. He specializes in natural history and large field experiments to show how multiple factors such as climate, predation and natural competition affect the environment.
When an ecosystem fails, the amount of water that is needed to restore it is much greater than the amount of water that was needed to sustain it before the collapse.
“Even if you increase rainfall up to a point where you would have vegetation in some other scenarios,” Dr. Pringle said, referring to photos of patches of grass in the savannas, can indicate the imminent destruction of an ecosystem.
“You can’t get the vegetation back, because that local facilitative effect has been lost,” he said.
The satellite photos show different areas in Africa that are in various states of vegetative decline. Some look like labyrinths of sand or, in some severe cases, deserts dotted with plant life.
Mound building termites of the savannas scavenge their surrounding areas and bring the nutrients together. The structures they build help the soil to retain water critical for life in dry climates. According to his research, the presence of these mounds and their ability to retain more water allow the land to go for longer with less water and also rebound faster after severe droughts.
Pringle explained how different animals have evolved over time to prefer different food and how his team uses fecal matter to determine the diets of animals they are studying. For example, Zebras eat the top of tall grass and usually come through an area first after a rain storm. Next come the Wildebeests that tend to prefer the intermediate portion of the grass.
The first step of this process is to “collect an extraordinary quantity and diversity of different kinds of feces from different kinds of large herbivores,” said Pringle.
Next the plant DNA is extracted and matched to reference databases to see what the animal is eating.
Plants respond by using a range of evolutionary techniques to secure their fate as a species. The plants growing in tree cover where predators can hide do not usually have many defenses to keep themselves and their fruit safe. This is because the herbivores are much less likely to venture into the groves so extra defense is unnecessary. Plants that thrive in much poorer soil with much less plant cover for predators to hide in, tend to have greater defenses such as barbs and even fruit that houses ant species to protect the plant and keep them from being eaten.