What does a Latin term like “in situ” have to do with feeding Earth’s inhabitants? The term means “in position,” or “in place,” and generally expresses the idea of “in its natural place.” Science uses the term to refer to organisms (most often plants) that have not been removed from their home habitats. An orchid that grows in the wild, perhaps in the branches of a tree, is growing in situ. One that grows in a greenhouse is not. (It’s growing ex situ, which will be the subject of the next pages.)

Until only a few years ago, scientific researchers who wanted to conserve species in situ were thinking mostly of saving species that lived in forests, or perhaps wetlands. The idea was that such species might have a difficult time growing anywhere else. Also, forests and wetlands are among the places that are most vulnerable to destruction by agriculture, logging, and development.

When plants grow in situ, they're able to evolve in concert with other organisms. This butterfly is spreading the pollen of the purple cone flower. (Fred Powledge)

In some cases, governments sought scientific advice and set aside specially protected areas for in situ growth. But in many cases, the “protected areas” were little more than places that were at the bottom of the developers’ want lists — places such as mountaintops and the most remote forests.

As of late in the 20th century, someone estimated that there were 9,800 protected areas in the world and that they covered more than 925,000,000 hectares. That sounds like a lot, but Eath’s total land surface is 14,894,068,900 hectares, or 57,506,000 square miles. (See the Measurement page for conversions.)

But more recently the scientists who study agricultural biodiversity have recognized the importance of in situ conservation of food plants and their wild relatives.

Why? One obvious answer is that when land is cleared to make way for farming, roads, shopping centers, and people’s homes, the wild relatives of our favorite foods are being wiped out. And once they’re wiped out in one place, they may never exist again. They may very well become extinct. In recent years, scientists have begun to realize just how useful those wild relatives of maize, rice, wheat, and dozens of other foods are in programs to breed better food crops. “Better” might mean more tasty foods, or foods with more nutritious value, or plants that do a better job of fighting off damaging bugs and diseases.

Another answer, perhaps not such an obvious one, has to do with the evolutionary change that occurs in plants, animals, and all other organisms when they live and reproduce in their own local environments (or “in the wild,” as some people put it). A plant species that is conserved in situ is going to slowly evolve to adapt itself to the environment in which it lives. If it doesn’t evolve, chances are that it will fail to survive.

Meantime, we're getting warmer.
Earth, unfortunately, is faced with an important example of this right now. Reputable scientists agree that the planet is undergoing a warming trend . Average temperatures in parts of the world are climbing. (See the forthcoming AboutBiodiversity section on Global climate change.)

The increase is perhaps only 1 or 2 degrees, which may not seem like a lot. But that’s enough to impose stresses on species that are accustomed to cooler environments. Some species will be able to accommodate themselves to the warmer environment (and some may thrive in it), but others may not be able to take the pressure, and they will die out.

	The ultimate in situ conservation site. (NASA)

There are other pressures that affect the evolution of species, including the foods we eat. Extremes of wetness or dryness may directly involve the plant itself, and they also may encourage or discourage the growth of insects (both harmful and helpful) and of pathogens that may harm the species.

If species are left in Earth’s evolutionary battleground, the one we call in situ, they may become extinct. A meteor crash or an outbreak of disease may wipe them off the face of the planet. But those who survive will continue to evolve. The asparagus of a thousand years from now will not have all the same characteristics of the asparagus we eat today, but it will at least survive and be better fitted for the environment in which it must live. It will be better equipped to fight off the diseases and insects that will have evolved in those thousand years.

So in situ conservation is important. And this means not only the in-place conservation of specific plants, crops, and wildlife, but also the ecosystems in which they live. When nations of the world gathered in Rio de Janeiro in 1992 to compose their Convention on Biological Diversity, they made no bones about the importance of conserving species in their home habitats. The document said, in part:

That sort of conservation can take place in protected areas, such as parks and nature reserves, but it also can happen in farmers’ fields. Farmers’ landraces are particularly important here. They provide a sort of low-tech evolution that helps to build the foods we will rely upon in the future.

In situ conservation is very important, but so is its cousin, ex situ. The following page tells about storing seeds and plant cuttings in tiny glass bottles and in very cold refrigerators and, in some cases, cryopreservation that promises to suspend the plant’s animation for hundreds of years.

Next: Ex situ conservation — Agriculture home page — Glossary — Site map
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