Specialized Pollination.

 

Some species of plants and bees have developed a close interdependence in connection withpollination. Such a mutual adaptation and interdependence between a plant and pollinator is a result of a long and intimate co-evolutionary relationship. The pollinating bees of the Brazil nut tree Bertholletia excelsa is an illustrative example of such a relationship and its economic importance. The Brazil nut tree grows wild in the Amazon Forest. Brazil nuts are one of the economically most important wild products growing trees in the area, with more than 50 000 tonnes of the nuts exported from Brazil every year. The Brazil nut trees cannot be grown in plantations, because they need to be pollinated by one special bee species, the small shining Euglossa bee. This bee is dependent on the presence of an orchid species that is found only in the rain forest. They are also the only pollinators for a number of orchids in the forest. In some species of Euglossa, the male bee collects some scented material from the flower, which they distribute to attract other males – who do the same and multiply the effect with a scented cloud, in the end so strong, that it attracts female bees so that mating can take place. During the collection of the scented material, male bees transfer pollen from orchid to orchid and pollination takes place. The female Euglossa bees live from nectar from the Brazil nut tree and pollinate it. This means that without the orchids, there would be no Euglossa bees and no Brazil nut trees, and none of the many other plants, insects and animals associated with that tree – including the people whose livelihoods include collection and sale of the Brazil nuts. Studies in the Amazon forest have shown that many Euglossa bees do not cross open areas. That means that great parts of forest lose its pollinators when the forest is cut, and open parcels of land are created between remaining forest islands. This example is only one of many important specialized interrelations between bees and trees. In spite of this, the bees perhaps play a minor role as pollinators in the rain forest compared to their role in temperate forests, monsoon forests and savannah woodland. In tropical rain forests, many trees are pollinated by birds, bats and insects other than bees. Animal pollination is of greatest importance, because there is no wind between the trees and because the distance between trees of the same species may often be great. In that way, it is most convenient for the trees to use animals as pollination vectors. In tropical forest, there may be rather few flowering plants on the ground because of the trees’ shade. In European deciduous forests, the forest floor can be totally covered by flowering plants in springtime, before the trees produce their leaves. These plants often need fast pollination from a greatnumber of honeybees. Not many other insects are present in high numbers in early spring. In Denmark, it is seen by forestry people that the presence of bees in forest areas helps to protect the newly planted trees from being eaten or spoiled from gnawing by roe deer, compared to other plantations with no bees. The reason is because bees secure a better pollination and seed production of so many other plants, which the roe dear can forage on instead of the tree seedlings. By pollinating trees, bushes and herbaceous plants, the bees are important for the food production of all the other animals and birds in the forest ecosystem dependent on it for food berries, seeds and fruits.