Good morning students,
My name is Tatiana Neklioudova. I am a biologist, mammologist (that means I have studied mammals), morphologist (that means I have studied morphology, in particular, morpho-functional features of the skin and specific skin glands in carnivorous mammals such as wolves, coyotes, foxes, and jackals; weasels, martens, and badgers; wild cats, lynxes, jaguars, and snow leopards; mongooses, civets and genets, hyenas and bears. In order to get samples for my research I worked in many expeditions where Russian scientists studied various ecosystems: the tropical rain forests in Vietnam (Indochina), the tropical savannahs in Ethiopia (Africa), the temperate grasslands in Russia, the deserts in Mongolia, the boreal forests and tundras in Russia. Today I am going to tell you about the tropical rain forest as the most exciting ecosystem for all researchers.
As you know, the true tropical rain forest is confined to a narrow belt around the equator, from 4o N to 4o S. Here there is little seasonal change in climate and precipitation, and temperature is always high and averages around 20-25 C (68-77o F) all year round. We worked in Vietnam, on the Tai Nguen Plateau, that is about 14o N. Here the climate shows seasonal variation. Certain weeks in the year may have little or no rain, and this places a stress upon the forest, where the vegetation is severely limited by the drought. One year we worked in December-February when there was a dry season, thus we could work around o'clock. Then next year we worked in April-May when a wet season had just begun, thus we had to spend afternoon in our field laboratories, under their roofs, because of really heavy rains that fall down like a wall of water. Such seasonal changes do not just cause some changes in working schedules for scientists, but they can also provide environmental cues for the intitiation of flowering, fruit production and breeding among animals. And we were glad to be able to compare data on the same ecosystem functioning in different seasons.
The tropical forests contain the largest bulk of living material per unit area of ground found in any biome, often amounting to over 45 kg/m2. The productivity is similarly high - up to 3.5 kg/m2 per year. The richness of the tropical forest extends into every kingdom of living organisms - plant, animals, fungal, and bacterial. The numbers of tree species alone are remarkably high, although they face many problems here, and the most significant are the shortage of light on the forest floor and poor soils. Because of high temperature, microbial activity in the soil is very high, so any organic litter falling from the canopy is rapidly decomposed. This releases mineral elements into the soil, but under conditions of high rainfall these can be easily washed out of the soils into rivers. The clays that serve the function to retain the nutrients in temperate soils are degraded and lost in the high prevaling temperatures in tropics, with the result that the soils become hardened and enriched with iron and aluminium, forming the red-coloured lateritic soils.
Tropical trees grow fast because of intense competition among saplings to reach the canopy - and the light - before their neighbours. Often they do not put out extensive branched canopies until they reach the light. They can be 40-to-50 m tall and 3-to-5 m in diameter, thus some tree species posess the buttress-like roots (counterforts) specializing in support the tree's weight and getting water and mineral elements from the upper layers of the ground. Some other plants overcome the light problem by using others for support, for example, lianas and climbers can be 200 m long or more, extending up from the ground to form winding trailers in the upper canopy layers. Falling organic litter may become lodged in the junctions of tree branches and form a peaty soil in wich other plants such as epiphytic plants that include orchids, bromeliads and some species of ferns become established. They have no roots on the ground, but use trees as a means of support, as a platform to receive the light which is sufficient enough for themselves and for such members of epiphytic communities as algae, fungi and invertebrate animals that live in these organic pockets as in microecosystems with their own nutrient turnover.
On the dark forest floor most animals feed upon the rich rain of organic mater from above. They are decomposers, like millipedes, that begin the process of decomposition finished off by microbes. The fungi, as well as some plants, also derive energy from the degradation of the organic matter. Other plants live as parasites.
Many animals make a living on the forest floor as omnivores, taking whatever food comes their way. There are the ants that feed on anything available from seeds and fungi to fallen caterpillars and provide food for the scaled ant-eater, pangolin. Large reptiles such as pythons and monitor lizards are poor climbers and they forage over a wide area. Some herbivores such as deer or omnivores such as various members of the pig family live on the forest floor and provide food for predators such as the tiger. Small ground animals are insectivores ad mixed feeders. Many emerge to feed only for a few hours (especially at dawn or at dusk) then hide away. By staggering their feeding times many different species can live in an area without to much confrontation.
In the understory we can find mid-zone flying animals such as insectivorous birds and bats and mid-zone climbing animals that include a large group of mixed feeders, mostly mammals such as squirrels, tree shrews and monkeys, but also snakes, geckos, and amphibians such as tree frogs. Movement is helped by numerous lianas that cross this space. These animals move vertically within their range, and may spend some time on the ground.
In the canopy are found many fruit-eating species, including monkeys, squirrels, bats and birds. These may be very specific in their habitats, confining their activities to particular layers of the forest where they find their preffered food. Thus the canopy layers have their own communities of insects, birds and mammals as well as the epiphytes and climbers that find a home there.
Now we can see that all this huge quantity of biomass of the tropical rain forest is well arranged in a complex spatial structure. Speaking about the extremely high biological diversity of the tropical forests, we have to keep in mind the stability of the climate, both seasonally and long-term. These stable conditions allowed a greater period for species diversity as well as for other encient species survival. Here you can find tree-ferns that occupied the planet during the Carboniferous period. Tree shrews, small shrew- or squirrel-like animals, are now generally classified in an order of their own (Scandentia), although they bear a striking similarity to early fossil primates, and therefore offer a tantalizing clue to what the first primates may have looked like and perhaps how they behaved. Here you can see the flying lemur wich managed to remain unchanged since the Pleistocene (Quaternary).
The tropical rain forests are complex and unique ecosystems that cannot be restored. The greatest management problem is the rate at which they are being desroyed. Selective logging for timber, clear felling for pulp production and destruction by burning for farming or commercial cattle ranching are all taking their toll on the world's dwindling tropical forests. Over 1% of the total area of the world's tropical forest is lost each year, and the rate is acelerating each year.
Apart from the concurrent loss of species, the destruction of the considerable biomass of the forest by burning puts large quantities of carbon dioxide into the atmosphere, adding to the greenhouse effect and global warming. Where crops or grass for cattle are planted the nutrient-poor tropical soils soon become exhausted, and taking away the canopy from above the soil allows penetration of solar radiation that bake the soils and destroys their structure. The result is a virtual desert, and the farmers and foresters thus move on to clear further areas. Rain falls directly on to the soil surface and causes extensive erosion, silting up rivers. Finally, the water cycle may be upset because less water is returned to the atmosphere by plant transpiration and that ultimately leads to reduced rainfall. As a result of our co-operative work with Vietnameese scientists in the expeditions, we had to give scientifically based advises how to develop systems of rational exploitation of the tropical forests that would combine economic gain for local people with ecological stability.
This report would not be complete without saying that during the research we had to face many problems and even a life-threatening danger. Our diet consisted of mostly rice with some addition of meat after a successful hunt. Once, after a division into two groups, we reached our biostation in the jungle just in two days because of using airplanes, whereas another group with all our food supplies had to spend more than a week on the road, driving from Hanoi to Anckhe. I was in the first group, and we were more concerned about bringing all our laboratory equipment than about food, thus we ended up with meals containing only soup made of wild green bananas that we had to eat for four days. Sure, I love banana as well, as you do. But there were not cultivated sweet bananas, but wild green tasteless ones. It was awful. Even our Vietnameese colleagues thought we all were going to die if our cars would be a few days more late.
Despite many stories about tigers and Asian elephants dwelling in the area where we were working, we saw none. The only thing we could see were tiger's claws and teeth on chains hanging around necks of lucky local hunters and some bones and scalps of elephants killed by local people. Of course, it was sad to know that people still hunt these endangered species for food or for other matter. Man kind is still the most dangerous creature on the planet. You see this sign - the cross made of two sticks. This sign marks the path which is dangerous to go along because of a hidden trap - a giant crossbow with a huge arrow that was set up for a large deer or a tiger. There is a hidden complex system of branches and lianes leading to the crossbow. When a large animal steps on to a branch, the entire system starts working, and in the next moment the poor animal (or an inattentive scientist) is shot by an arrow. We tried to keep in mind all said above, avoid such paths and be polite with local people armed with smaller crossbows they used to hunt birds and small animals.
While working in the forest, we had to be aware of poisonous snakes. Sometimes we could not relax after work even in the camp. For example, this most poisonous bamboo green snake was found in our kitchen.
Although, the most troubles came with the smallest, but very numerous animals such as mosquitoes carrying malaria and leeches sucking our blood. And what was the worst: there was no known repellent for leeches that live on the ground and wait for you sitting on grass and bushes. As all leeches, after they bite you, they use the ferment (enzyme) a protein that blocks your sensitivity to pain and you feel nothing until you find a huge, brown, and satisfied sack full of your blood. The only protection we could use was that we had to be completely clothed even it was really hot. Although local people did not pay much attention to leeches. Most of the time they walked barely naked, and from time to time they clean up their bodies with a stick that they always carry in their hand.
So, as you can see the profession of a scientist is the most interesting and exciting one.