Prof. David Tilman : 2. Rich Natural Environment Produces More

2. Rich Natural Environment Produces More

Importance of Biodiversity

Although everybody knows the importance of biodiversity today, few people emphasized it in the 1970s. Productivity is important for humans. In terms of land, productivity is the amount of production per unit area. Even scientists used to think that greater biodiversity did not necessarily lead to higher productivity of land.

Biodiversity Experiments

However, Tilman believed biodiversity was a major factor to improve land productivity. He decided to prove it by conducting experiments at an actual farm. It was the world's first large-scale experiment, in which the influence of biodiversity on productivity was investigated.

Professor Tilman's Experimental Farm

(1) In one corner of a field station, many 9-meter-square plots were prepared.
(2) Each plot was planted with either 1, 2, 4, 8 or 16 different prairie perennial species, all randomly chosen; their growth per unit area was observed for over 20 years.

Tilman's experiment has shown that biodiversity is of central importance to the productivity, stability, resistance to invasion of ecosystems, and to the fertility of their soils. For example, plots seeded with 16 different species were 200% more productive than these same species grown in monoculture plots. It was a discovery that overturned the conventional wisdom of ecology.
Thereafter, many scientists conducted similar experiments in other types of ecosystems to examine whether the result of Professor Tilman's experiment was correct. We now know that loss of biodiversity harms almost all aspects of ecosystem functioning.
Biodiversity matters because each species is different and has its own specialized skills. Each species evolved specialized skills that were gained at the cost of not having other skills. That is why so many different species of plants and animals coexist with each other on earth.

Human society functions in the same way. There are thousands of different occupations, and different people develop different skills required by society. This coexistence enables society to function.
However, humans have become a superspecies. We have accumulated knowledge and skills over our long history, passed them down through the generations. We began to raise crops and livestock. While most living organisms must coexist to live, humans have become able to live without coexisting with other species, by learning to control them and to make them work for us. We have become animals that cause other species to go extinct, are destroying ecosystem, and causing a wide range of environmental problems. How should we act from now on?

3. Sustainable Agriculture for People and the Environment