Monoculture

Monoculture involves the culture of a single species with or without the addition of fertilizers or feeds. Only a few applications of organic fertilizers without appropriate instructions have been conducted by the farmers in central and northeast Thailand to increase fish production. Fertilizers commonly used by local fish farmers are manures from cows, buffalo, pigs, and chickens. Inorganic fertilizers are not commonly used.
A typical example of controlled stocking monoculture with the addition of organic fertilizers is the culture of Nile Tilapia, Sarotherodon nilotica. With a stocking density of 2 fish per m2 of pond surface area, production of 25000kg per ha at least twice as many as fish as can be produced from naturally occurring organisms, is possible after four months of rearing by adding pig manure everyday for five days a week at the rate of 75 kg per ha per day.
Supplementary feeding is another means that can increase the production of fish culturing in ponds. At present, some commercial fish farmers use rice bran and broken rice to feed fish. Water spinach, duckweed, and other aquatic weeds, soybeen, cake, peanut cake, fish meal, and fresh or frozen trash fish are also used.
It is unfortunate that the word "monoculture" has been borrowed from agriculture and applied to forestry as if it meant the same thing.
In farming, a monoculture means that you remove the entire natural ecosystem, pile the roots and debris and burn them, plow the soil and plant seeds of a food or fibre crop, usually exotic in origin. This kind of monoculture never happens in nature in the absence of human intervention.
In forestry, a monoculture forest refers to a forest that is dominated by a single species of tree. This is a very common feature in forests that grow back after natural disturbances such as fire, flood, landslide, or insect attack. Natural monocultures are common in northern coniferous forests such as the temperate rainforests and boreal forests of North America, Europe, and Russia.
The forest depicted above may be technically a monoculture as the word is used in forestry. But it is a fully functioning forest ecosystem containing thousands of species of mosses, ferns, fungi, herbs, shrubs, birds, insects, reptiles, amphibians, and mammals.
Rather than viewing forests as either "natural" or "monoculture" it makes much more sense to consider the broad gradation of forest types, some greatly influenced by human activity and others not so influenced. Some natural forests are rich in tree species while others are dominated by a single tree species. Pioneer tree species such as lodgepole pine, poplar, some of the spruces, etc. often form natural monocultures in the wake of wildfire. Managed forests can contain a wide variety of tree species while others are similar to natural monocultures. In British Columbia, for example, where forest management is based on native tree species, the new forests growing back after logging are slightly higher in tree species diversity than the original forests*. This is because the pioneer hardwood species such as alder, birch and maple are more abundant in young forests than in older ones.
Of course there are monoculture plantation forests that are truly tree farms, with monocultures of exotic, hybridized trees planted in rows. These forests are often established on land that has already been cleared of its original forest for agriculture. In Brazil, many of the eucalyptus plantations are on land that had been burned out by inappropriate farming practices. They represent a form of ecological restoration compared to what was there previously. In addition, it is the practice in these plantations to restore at least 20% of the land to native forest, particularly the riparian (river-side) areas. There is a good example of this in the State of Espirito Santo on the Atlantic coast north of Rio de Janeiro. Here the Aracruz Cellulose company is working with the World Wildlife Fund to re-introduce native animals, plants, and trees to the region. 150 native tree species are grown in the nursery and planted out in the network of natural areas amidst the eucalyptus plantations.
I would rather see the land covered with native forest, young or old, than an exotic monoculture plantation. On the other hand I will choose the monoculture forest over a field of sugar-cane or wheat any day. And so will most of the birds and animals and insects. In my opinion, any forest is better than no forest.

see "British Columbia's Forests: Monocultures or Mixed Forests? Province of British Columbia, Ministry of Forests, May 1992.