FAO has its headquarters in Rome, Italy, and was one of the first agricultural institutions to promote the use of horizontal resistance in its International Program for Horizontal Resistance (FAO/IPHR). Food chain
The food chain is an ecological concept, and it is a form of eating hierarchy, with the smallest and most numerous animals at the bottom of the hierarchy. These animals may eat plants or each other. With increasing rank, the numbers get smaller, and the animals get larger. As a general rule, the animals of one rank eat animals in a lower rank (except for parasite which may inhabit animals much larger than themselves). Each rank may be thought of as a link in a chain that stretches from the lowest to the highest level. Animals in any rank may also eat plants.
A low concentration of toxins, particularly fat-soluble and water-insoluble toxins such as DDT, in the environment tends to increase as it travels up the ranks of the food chain (see biomagnification), and it may reach dangerous levels at the top of the chain, in birds of prey, and large mammals, including people. Foreign parasites species of plant parasites that are absent from an area, but which could become serious if accidentally introduced. Foreign parasites are the main cause of crop vulnerability. Forestry
The cultivation of trees for timber. This term also includes the exploitation of natural forests for timber. Many forest tree species offer scope for amateur breeders , mainly by selection within existing populations. However, because most forest species are open-pollinated, a good parent tree will be only a half-sib.
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