Earth Science: Ecology – Human Environmental Impact
Humans have changed their environments according to their needs from time immemorial.
A typical change to natural ecosystems is the clear-cutting of forests for food production. Many natural ecosystems are also destroyed due to increasing urban development.
Earth Science: Biology – Ecology – Agricultural Ecosystems
Agricultural ecosystems, or cultivation ecosystems, are created by humans for agricultural use—that is, mainly to produce food and other biological raw materials. These humanmade ecosystems come to replace natural ones.
Agricultural ecosystems need to be cultivated and, therefore, controlled and monitored. For example, the level of nutrients needs to be topped up regularly by fertilizers, as the removal of the crop disrupts the material cycle. Without fertilization, an agricultural ecosystem breaks down within a short period of time and sooner or later converts back to an environment that is governed by natural processes.
To ensure economically viable agricultural areas, it is often perceived necessary to clear cultivated areas of all noneconomic species, which results in monocultures of a single crop species being sold. These monocultures are very different from the natural environment. They reduce the diversity of plants and animals to a minimum and shorten food chains.
Native animal and plant species are eliminated not only due to intensive cultivation but also due to the use of insecticides, fungicides, and herbicides used to protect crop plants. Populations of other organisms, especially so-called weeds and pest species, often grow significantly as a result (see in focus).
They may even invade the area from other regions. Ecosystems adjacent to intensively cultivated areas are also often negatively impacted. For instance, fertilizers and pesticides may be washed from a field into creeks and rivers. In this manner, toxic substances may accumulate in the food chain. In an attempt to tackle these problems-and also to recognize the growing awareness of these concerns among consumers-some agricultural products are now being produced in more ecologically sound ways.
These involve recognizing natural material cycles and cutting down on the use of synthetic fertilizers and pesticides as much as possible, even if the crop yield may be lower. The more naturally an agricultural area is maintained, the greater its ability to self-regulate. This is a typical characteristic of natural ecosystems.
PESTS ON THE INCREASE
In order to maximize the use of agricultural areas, most are cultivated as intensively as possible by planting vast areas with only one type of crop. However, such monocultures are ideal environments for pest species, which may populate these areas very quickly.
These pest species are usually killed by the use of insecticides, herbicides, or fungicides, which is certainly effective in the short term. However, not only do these toxic sub-stances accumulate in the food crops, but the pest species also develop resistances against such pesticides within only a few generations.
Pest control then becomes a real challenge. Therefore, biological methods are becoming more and more popular as long-term solutions for pet control