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close this bookDiversity, Globalization, and the Ways of Nature (IDRC, 1995, 234 p.)
close this folder13. Diversity and human survival
View the document(introduction...)
View the documentDocumenting diversity
View the documentResources for the future
View the documentDiversity of living systems
View the documentCauses and effects of the loss of natural diversity
View the documentDiversity and culture
View the documentRestoring what is lost
View the documentBiodiversity and research

Causes and effects of the loss of natural diversity

Before industrial times, social insertion into natural complexes resulted in the use of natural diversities with only secondary negative effects. In most cases, social action adapted to the natural environments and when it did not, the societies at fault suffered the effects of their damaging actions. After the industrial revolution, societies began to use natural resources and the environment without regard for the need to sustain its productive and natural support base. The damage caused by these forces has affected not only the natural environment, but also social and cultural environments.

The impoverishment of natural systems has a more serious and widespread effect than is obvious at first. In the last decades and even now, rich, stable ecosystems with many thousands of species are being replaced with monospecific plantations that require a large investment of energy and resources to be sustained.

Plantations are essentially unstable. They are systematically invaded by “pioneers” (the agronomists call them “weeds”) from neighbouring ecosystems, both plants and animals. These organisms - arriving on their own without the natural control of their predators - grow, feed, and reproduce in the new niche provided by the crop, affecting its productivity and health. In practice, there is interference between the crop and the surrounding ecosystems affecting both the ecosystems and the plantation itself. The latter functions as a new, artificial, highly unstable ecosystem.

In addition to the local organisms that adapt to the new system, plantations bring their own flora and fauna, including various plants and animals transported with the seeds or with expansion of the plantation. Crops also constantly develop diseases promoted by the concentration of individuals or seeds of a single species in reduced spaces. Viruses, bacteria, protozoa, fungi, and various parasites reproduce and thrive in the monospecific crop. Such crops require repeated treatments to prevent or cure their frequent diseases.

Pesticides are a set of toxic substances required by monospecific agriculture to eradicate undesirable biological interference. They represent one of the main tools of biological uniformity. The ideal pesticide kills everything but the crop species and, perhaps, allies, such as pollinators. As a result of their toxicity, the effects of pesticides reach far beyond the crop zone to other terrestrial and aquatic environments. For this reason, when plantations are established, a huge reduction in the diversity of all natural local systems takes place.

The forest of Misiones in South America, with tens of thousands of species, has been replaced by ecosystems based on two or three species of trees and some other species that have adapted to the change. The grasslands of Uruguay contain over 2 thousand species in each local area; the eucalyptus and pine plantations that have been introduced in prairie grasslands only contain the planted species and a few “intruders” that succeed in nesting or adapting to the new niche.

Generally speaking, when multispecific ecosystems are transformed into monospecific artificial systems, the species that manage to adapt to the new environment do so in an unbalanced manner. In some cases, without natural predators or constraints, uncontrolled growth may take place. The result is a decrease in effective and potential resources.