A PEEK AT ANOTHER ASPECT OF MOTHER NATURE

by Jack Ewing

Mother Nature is not only a nurturer but also a destroyer. In The Diversity of Life, Edward O. Wilson tells of the explosion of the volcano Krakatau in Indonesia, a perfect example of the extreme cataclysmic force that Mother Nature can set in motion when it serves Her purposes.

Krakatau, once a volcanic island of about 80 square kilometers, exploded on August 27, 1883 with a force equal to approximately 150 megatons of TNT. To help make sense of those big numbers, let’s take a look at the first atomic bomb ever deployed, which was exploded over Hiroshima, Japan on August 25, 1945. In that blast 80,000 people died instantly, but the Hiroshima bomb was only 15 kilotons, one ten-thousandth as big as the explosion of Krakatau. 

The Volcanic Explosivity Index (VEI), created by the US Geological Survey, measures the strength of volcanic explosions just like the Richter scale measures the strength of earthquakes.  For Krakatau it was about 6, meaning that around 20 cubic kilometers (about 8,300 times the volume of the Houston Astrodome) of ash, dirt, and rock were thrown five times as high as a commercial airliner normally flies. The sound was heard for almost 3,000 miles - or roughly the distance between New York and Los Angeles. The explosion and accompanying seismic activity created a tsunami that killed about 36,000 people in the surrounding lands. So much sulfur—some estimates are as high as 20 million tons—was released into the atmosphere that it reduced the amount of sunlight reaching the surface of the earth and the average temperature dropped by 1.2 degrees Celsius for five years.  The volcano and most of the rest of the island sank into the sea, leaving a crater seven kilometers in diameter.

Rakata, which had been a mountain on the far end of the island, about 20 kilometers from the volcano, was the only thing left of the island. It was sterile and completely devoid of life. Then, after this act of total destruction, Mother Nature put her creative talents to work.

100 years after the explosion, Rakata was completely covered with a lush tropical forest. There were 30 species of land birds, 9 species of bats, the black rat, 9 reptiles, and 600+ invertebrates.

In describing the re-population of Rakata, Edward O. Wilson tells us:  “A community does not arrive on the shores of such an island as a finished product. Instead, it is stacked like a house of cards, one species on another, loosely obedient to assembly rules. 

Most propagules, whether plant seeds or wandering bird flocks, are doomed to failure. For them the soil is wrong, the forest glades are still too small, the prey species have not yet arrived, or formidable competitors wait at the shore. Even many of the species established earlier cannot hold on as conditions inevitably change: grassy swales are closed out by forest growth, disease strikes, a stronger competitor invades, or chance fluctuations in members bounce the population to zero. 

The community shifts continuously, and by an unconscious trial and error, through innumerable fits and starts, its biodiversity slowly rises. Species excluded earlier at last find room, symbiotic pairs and trios are fitted together, the forest grows deeper and richer, new niches are prepared. The community thus approaches a mature state, actually a dynamic equilibrium with species forever arriving and disappearing and the total species numbers bobbing up and down inside narrow limits”. - Edward O. Wilson, The Diversity of Life 

When rice fields and cattle pastures on Hacienda Barú were abandoned to the whims of Mother Nature, secondary forest returned surprisingly quickly. The oldest parcel of former farmland on Hacienda Barú was a cornfield that was here when I arrived in 1972. After the corn was harvested, the parcel was not used again for crops or pasture, and natural regeneration began. Today, 53 years later, there is no trace of the former corn patch, and the parcel is now covered by a mature secondary forest with trees as high as 40 meters. 

The first trees to return to that parcel were 90% the same species. For example, Quamwood (Schizolobium parahybum), is a soft wood similar to balsa, that grows as high as 40 meters in 15 to 20 years and then topples over, usually being uprooted during a storm. The clearing created by the fall of each tree then became a seedbed for other tree species. A quick count showed 12 different species of rainforest trees growing there as of August 2020, 48 years after the corn patch was left to nature.

Over the years we at Hacienda Barú National Wildlife Refuge have returned approximately 150 hectares to Mother Nature. With each parcel, we simply stopped chopping the weeds or trying to intervene in natural processes other than planting a few trees and maintaining some nature trails. The species of trees we planted were species that had been found there before the land was deforested in the early 1900s, but had become locally extinct, or nearly so. Each time we abandoned a pasture or field, the process of regeneration of jungle was different, depending on the terrain, the soil, the seeds available from neighboring forest parcels, and what species had been there before the land had been deforested. 

Hacienda Baru 1972 and again 2015

Certain types of pasture were the most difficult for the forces of nature to overcome, such as those that grow in wet areas and form a thick mat of tangled roots that prevents other plants from getting a foothold. A species called German Grass was able to prevent the appearance of any other types of plants for 10 to 12 years. Eventually, a single royal palm appeared in the middle of the former pasture. 

As that palm grew, its leaves created shade causing the grass beneath it to lose vitality and die. Soon several types of leafy vegetation appeared under and around the palm, and later trees. These plants formed what looked like an island of thick jungle in the middle of a sea of grass, and the island grew - slowly - but it grew. Five years later and not far away, another island formed, also beginning with a royal palm, and it grew. Today, 53 years after the cessation of human intervention, more islands have formed and grown and have joined together. Ninety percent of the land is now in forest, and the islands continue to grow and close out the remaining patches of German Grass.

This is a perfect example of the creative aspect of Mother Nature. This is a cycle. The land that is today called Hacienda Barú has been deforested by humans twice that we know of, once by indigenous peoples and once by settlers of European descent. The first deforestation ended around the year 1500, and the forests returned and prospered with no human intervention for 400 hundred years. In the early 1900s the next wave of humans, the ancestors of many of the families who live here today, migrated to the coastal region of southern Costa Rica, felled and burned the jungle and planted crops and pasture. 

In 1972 when I first set foot on Hacienda Barú it was about half pasture and rice fields, and the rest was rainforest and other natural areas like mangrove and wetlands. Today it is 96% natural areas and 4% human-managed areas, including a hotel, a research center, several houses, and an area that was planted with teak trees in 1985-86. These trees have been harvested, and the land is now covered with species of trees native to Costa Rica.

It may seem strange to some readers, but I consider the effects of human activities to be an integral part of the above-described natural cycle of the destruction of rainforest to produce food for the exclusive consumption by humans, followed by its regeneration. Humans are a part of the natural world as much as the species of plants and animals they destroy. They are only doing what every other species on the planet is doing, struggling to survive and acquire as big a share of the available resources as possible. Our intelligence has allowed us to take a huge portion of those resources. Let’s have a look at another species that is trying to take as much as possible as fast as possible. In so doing it causes extreme anguish and pain to another species.

One chapter of Monkeys Are Made of Chocolate, “Hateful Devils the Ants Won’t Even Eat”, tells a story about vultures and a cow that was having difficulty giving birth to a large calf. When I found her, she was lying flat on her side, exhausted, unable to stand up and straining for all she was worth trying to expel the calf, which was stuck with part of its head and one front foot exposed. They were surrounded by vultures. Part of one of the calf’s toes, a chunk of its nose, and most of its tongue were missing, eaten by the vultures, as was part of the cow’s vulva. Two of the cow’s teats had been eaten, and milk was dribbling out of the stubs. She was moving her head around frantically in an attempt to bat away several vultures that were trying to pluck her eyes out. To this day, I remember the pain I felt upon seeing the desperation and anguish in the eyes of that cow. My point in bringing up this incident--that will surely provoke revulsion in some readers--is to illustrate that I, a human being, was repulsed by the sight and felt extreme hatred for the vultures, but Mother Nature saw it much differently. From her point of view, the vultures were simply doing what they do to survive. Normally, they eat carrion, but when flesh of any kind is available, dead or alive, they go for it and consume as much as they can as fast as they can for as long as they can before a larger more aggressive scavenger comes around. They were indifferent to the fact that both the cow and calf were still alive. Food is food, and competition is fierce. Waiting around for the cow and calf to die isn’t an option.

Mother Nature is not only a nurturer. She can also be destructive and cruel.

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Jack is currently president of two environmental organizations, ASANA (Frends of Nature of the Central & South Pacific) and FUNDANTA (Foundation for the Path of the Tapir Biological Corridor)

A natural–born storyteller, Jack’s articles have appeared regularly in Costa Rica publications, and he is author of several books, Monkeys Are Made of Chocolate and Where Tapirs and Jaguars once Roamed: Ever–Evolving Costa Rica. His latest book is titled Monkeys Are Made of Mangos.