Seeding the Earth: When We Lose an Animal, We Lose a Forest

Candice Gaukel Andrews November 25, 2014 9
Grizzly mom and cub

In British Columbia, bear viewing generates twelve times more in visitor spending than bear hunting and more than eleven times in direct revenue for the provincial government. ©Candice Gaukel Andrews

When we hear news about the declining numbers—and even near-extinction—of some of the world’s largest animals, such as tigers and rhinos, we usually think about that loss in terms of the planet’s diminishing animal biodiversity and what we can do to conserve what’s left of these species. But new research results from the University of Florida published earlier this month show that we stand to lose much more than those specific forms of fauna.

For millennia, elephants have been important cultural, national, and spiritual symbols in Thailand. At the beginning of the twentieth century, elephant numbers there exceeded 100,000. Today, however, it is estimated that only 2,000 wild elephants remain in Thailand, largely due to capture in order to meet the demands of Thailand’s tourist industry or poaching for ivory and meat.

According to the University of Florida report, this overhunting not only decimates the elephant population, it has widespread effects on the forests in which they live. When wildlife is killed or removed from a natural habitat, then, we kill that particular environment itself.

What will this mean for Asian forests; and by extension, the forests on our own North American continent?

Seeds hitchin’ a ride

The International Union for Conservation of Nature (IUCN) lists African elephants as vulnerable and Asian elephants as endangered. ©Eric Rock

The International Union for Conservation of Nature lists African elephants as vulnerable and Asian elephants as endangered. ©Eric Rock

The results of the University of Florida study are reported in the November 2014 issue of Proceedings B, the Royal Society of London’s flagship biological research journal. The authors demonstrate how vital large animals are to maintaining the biodiversity of tropical forests in Thailand and how overhunting or removal of them leads to the extinction of a dominant tree, the Miliusa beech (Miliusa horsfieldii), with likely cascading effects on other forest biota.

The research is the first of its kind, quantifying the decades-long effects of animal seed dispersal across the entire life cycle of the trees—from seeds to seedlings to adult trees. Using more than 15 years of data from the Thai Royal Forest Department, the scientists looked at the growth and survival of trees that sprouted from parent trees and grew up in crowded environs, compared to trees from seeds that were widely transported across the forest by animals.

A long-term simulation on millions of seeds run on the University of Florida’s supercomputer showed that trees that grow from seeds carried by now-overhunted animals are hardier and healthier than those that are not. That means that the loss of animal seed-dispersers, such as elephants, increases the probability of tree extinction by more than tenfold over a 100-year period, putting the whole biological community at risk.

Forests flagging

I have written before about whether or not the hunting of one animal can help the fate of the many. At the time I was writing about that issue, I wasn’t sure of my own position, given the good one animal slated for a trophy hunt could do for the conservation of the rest of that particular species. Then, after my post on the Great Bear Rainforest, a reader wrote in and urged me to take a stand on the hunting of grizzly bears there. That’s why this new research out of the University of Florida caught my attention. Poaching, trophy hunting, or the removal of even a single animal from its habitat is about so much more than just the loss of that species. It’s about the loss of an entire ecosystem.

elephants at sunset

The loss of seed-dispersing elephants increases the probability of tree extinction by more than tenfold over a 100-year period. ©Dave Luck

In British Columbia, according to the Raincoast Conservation Foundation, trophy hunters kill 300 to 400 grizzlies every year. This is allowed despite the fact that bear viewing generates twelve times more in visitor spending than bear hunting and more than eleven times in direct revenue for B.C.’s provincial government. And in line with the results of the University of Florida study, not only are the grizzlies themselves at risk, the great British Columbia forests are in jeopardy.

When salmon spawn, they feed the bears, coastal wolves, eagles, and ravens. These predators pull the salmon onto the shorelines; coastal wolves drag the carcasses even farther into the forest, where they feed thousands of insects and microorganisms. The decaying fish release nitrogen—nature’s superfertilizer—into the soil around them. This high concentration of salmon-derived nitrogen is what causes the trees along the coast and in the river valleys to grow so large. In turn, they create havens for bears, birds, and wolves.

It seems to me now that with each elephant that is removed from a forest in Thailand, a beech tree disappears, too. And for every grizzly that is taken from our continent’s coast, one more red cedar is not given a chance to live a thousand years.

And that may be the real meaning of one animal’s loss.

Here’s to finding your true places and natural habitats,

Candy

9 Comments »

  1. Brian Bastarache December 1, 2014 at 8:26 am - Reply

    The loss of a species is accompanied by the loss of the ecosystem functions provided by that species. Trophic cascades sometimes follow and potentially imperil more species. Read anything by Paul Martin, particularly Twilight of the Mammoths. Follow that/those up with Connie Barlow (Ghosts of Evolution) and Sharon Levy (Once and Future Giants). These authors has drastically changed the ways that I view conservation.

    • Melissa Kelly December 3, 2014 at 2:39 pm - Reply

      Thanks for these references Brian, and for your article Candy. It needs a facebook link so I can put it out there for my nonbiologist friends (and bosses) to read.

  2. Lawan Bukar Marguba November 30, 2014 at 5:23 pm - Reply

    This is rather an age old practical wisdom.Animals in their natural habitats are like meticulous traditional farmers. Many plant species onlt thrive when animals are around. Animals know when and how to nibble new shoots from trees and shrubs, they enrich the soils around plants by their urine and droppings. Animals are sometimes the only vehicles for enhancing the viability and germination capacity of certain plant seeds and nuts, etc.

    Thorn forests like those of Faidherbia albida, Acacia senegalensis can only thrive where animals browse. So to that effect it is plain that even those forest ecosystems where little research or every day observations have not been formally conducted about the intrinsic relationship of animals and plants, it would be safe to assume that the University of Florida claim should be a food for thought.

  3. Freddy Pattiselanno November 27, 2014 at 9:04 am - Reply

    Great! Gaining more useful information. Good work Candice.

  4. Paul McGovern November 26, 2014 at 1:01 pm - Reply

    Great discussion Candice. Great story one that people need to wrap their heads around.

  5. Adriana Consorte-McCrea November 26, 2014 at 12:59 pm - Reply

    Very interesting, crucial and stimulating… Thank you, Candy

  6. Sinnadurai Sripadmanaban November 26, 2014 at 12:57 pm - Reply

    We lose animals, birds, rodents etc due to hunting for flesh, for hide, for body parts as well as by trophy/sport hunters. Deforestation too leads to diminishing biodiversity & lack of food.

  7. Thomas Sawyer November 26, 2014 at 12:56 pm - Reply

    Interesting perspective………….

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