Plants of equatorial forests. Humid equatorial forests
Jungle, or scientifically, rainforests, from the tops of the trees to the forest floor are filled with life. Are found here animals, about each of which you can write a separate report: a crocodile, anteater, hippopotamus, bat, sloth, koala, chimpanzee, porcupine, gorilla, armadillo. Insects: termites, tropical butterflies, mosquitoes. Tarantula spiders, hummingbirds and parrots. Hundreds of species of plants, birds, and animals feel comfortable in the rainforest.
Select a report about a rainforest dweller:
What does "tropics" mean?
The tropics are the forests that grow at the equator. These forests are the most important ecosystem on the Earth. The coast of the Gulf of Mexico and Brazil, the South American coast, the West Indies, part of Africa, the island of Madagascar, and some Asian countries and the Pacific islands are occupied by tropical thickets. The tropics make up only 6 percent of the land area.
High humidity and hot climate are the main features of the fabulous variety of forms of life here. Constant warmth, frequent, abundant, short tropical showers contribute to the rapid growth and development of flora. And the fauna, thanks to the abundance of water, also does not suffer from drought. Rainforests have red or patchy soils, and the forest itself is multi-tiered, and each level is densely populated. Such a variety of flora and fauna is possible due to ideal living conditions.
Who lives in the rainforest and how?
The wilds of the forest are inhabited by a variety of animals. Giants-elephants and small insects, birds and animals of medium size, can live simultaneously in the same area of the forest, but at different levels, finding shelter and food in the forests. No other place on land possesses such a wealth of ancient life forms - endemics. Due to the dense foliage, the undergrowth in the rainforest is weak and the animals can move freely.
The variety of animals in the rainforest is striking: along with reptiles (turtles, crocodiles, lizards and snakes), there are many amphibians. The abundance of food attracts herbivorous animals. Predators (leopards, tigers, jaguars) come after them. The color of the inhabitants of the tropics is rich, since spots and stripes help to better camouflage in the forest. Many species of ants, tropical butterflies and spiders provide food for hundreds of bird species. The tropics are home to most of the monkeys on the planet, there are more than one and a half hundred parrots, 700 species of butterflies, including giant ones.
Unfortunately, many representatives of the jungle fauna (antelopes, rhinos, etc.) were exterminated by humans during colonialism. Now many animals that previously lived freely in tropical forests have remained only in reserves and zoos. The destruction of forests by humans leads to a reduction in fauna and flora, soil erosion, and a loss of the ecological balance of our planet. For decades, rainforests - the “green lungs of the planet” - have sent us a message signaling that people must be held accountable for their actions.
If this message is useful to you, it's good to see you.
As a biogeographic unit of the subdivision of the living cover of the land at the global level, the types of biomes are distinguished, to a certain extent close to the zonal types of vegetation and animal population. The types of biomes that form in different hydrothermal conditions differ in the spectrum of life forms and the most important features of the structure of the communities they comprise. Each type of biome has its own, characteristic only of this type, variants of the structure of communities; territorially and dynamically conjugated rows of biogeocenoses are formed. The main types of land biomes are shown in Fig. 60.
Tropical moist evergreen forests
These forests are common in humid areas with an annual rainfall of 1500 to 12000 mm and more and a relatively even distribution throughout the year. An even annual course of air temperature is characteristic: the average monthly indicators fluctuate within 1 - 2 ° С. The daily temperature range is much higher and can reach 9 ° C. Under the forest canopy, especially on the soil surface, the diurnal amplitudes sharply decrease. Thus, the hydrothermal regime of the areas of distribution of humid evergreen tropical forests during the year is optimal for the development of living organisms.
Humid evergreen tropical or evergreen rainforests are concentrated in three vast regions of the world: northern South America (including the vast massif in the Amazon) and adjacent Central America, western equatorial Africa, and the Indo-Malayan region.
Vegetation. Forests of this type are among the most complex plant formations on Earth. One of the striking features is their amazing richness of species, huge taxonomic diversity. On average, there are 40 to 170 tree species per hectare; herbs are much less (10-15 species). Considering
Rice. 60. Zonal types of land biomes (G. Walter, 1985): I - evergreen tropical rain forests, almost without seasonal aspects; II - tropical deciduous forests or savannas; III — subtropical desert vegetation; IV - subtropical sclerophilous forests and shrubs sensitive to frost; V — temperate evergreen forests sensitive to frost; VI — frost-resistant deciduous deciduous forests; VII - steppes and deserts of regions with cold winters, frost-resistant; VIII - boreal coniferous forests (taiga); IX - tundra, usually on permafrost soils; flooded contours - alpine vegetation
a variety of lianas and epiphytes, the number of species in a relatively homogeneous forest area can be 200 - 300 and more. The predominant group of life forms are phanerophytes, represented by evergreen hygromorphic and megathermal crown-forming trees with slender and straight smooth light green or white trunks, not protected by bark, branching only in the uppermost part. Many are characterized by a superficial root system, which takes a vertical position when the trunks fall. Over 70% of tropical rainforest species are phanerophytes.
The change of leaves in trees occurs in different ways: some plants shed them gradually throughout the year, while others are characterized by a change in the periods of leaf formation and dormancy. The change of leaves at different times on different shoots of the same tree is also quite remarkable. Leaves are often devoid of kidney scales, sometimes they are protected by pressed bases of petioles or stipules.
Tropical trees can bloom and bear fruit continuously throughout the year or intermittently, several times a year, many species annually. Among the important ecological and morphological features, the phenomenon of caulifloria should be noted - the development of flowers and inflorescences on the trunks and large branches of trees, especially those located in the lower tiers of the forest.
Also presented are perennial grasses and groups of plants, often called extra-tiered or inter-tiered: lianas, epiphytes, semi-epiphytes. Each of these groups of life forms is distinguished by peculiar ecological adaptations.
Among the lianas and climbing plants, woody forms are predominantly developed, but herbaceous forms are also found. Many of them have rather thick trunks (up to 20 cm in diameter), which, climbing up the trunks of supporting trees, twine around them like ropes. As a rule, vines' leaves are developed at the level of tree crowns. Lianas are diverse in the way they climb support trees. They can climb on them, clinging to the antennae, twine around the support, lean on the trunk with shortened branches. Among the large lianas, there are species comparable in height with
the tallest trees. They sometimes grow so fast and develop such a mass of branches and leaves on the top of the trunks that they destroy the trees that support them. Often, the vines are so intertwined with the branches of the crowns of several trees that the dead tree does not fall, supported by the vines for a long time. The dense crowns of vines drastically reduce the amount of light penetrating under the forest canopy. Lianas grow in abundance along forest edges, along river banks, in lightened areas.
Epiphytes are equally diverse, using trunks, branches and even leaves of trees as a substrate for settlement, but not absorbing water and mineral nutrients from living organisms. All of them are saprophytes, they receive nutrients from dead organic matter, sometimes with the help of mycorrhiza.
According to the forms of growth, epiphytes with cisterns, nested and epiphytes-sconces are distinguished.
Epiphytes with cisterns accumulate water in the rosettes of leaves and use it with the help of adventitious roots penetrating into them. In the rosettes, peculiar microcenoses of the second order arise, with algae and numerous aquatic invertebrates. This group of epiphytes includes representatives of the bromeliad family living in the forests of Central and South America.
Nesting epiphytes and sconce epiphytes are characterized by the ability to accumulate nutrient-rich soil between the roots forming a "nest", as, for example, in the "bird's nest" fern.
Semi-epiphytes evolved from lianas climbing with the help of roots, through the gradual loss of connection with the soil as a necessary condition for existence. Semi-epiphytes remain alive if all the roots that connect them to the soil are cut.
Epiphytes play an important role in the life of a tropical rainforest: they accumulate up to 130 kg / ha of humus and intercept up to 6000 l / ha of rainwater, more than the leaves of trees absorb.
The number of families (as well as species) of herbaceous plants is much smaller than that of woody ones. Among them, madder is well represented, a small number of grasses are constantly present, selaginella and ferns are common. Only on glades in the middle of the forest does the grass cover acquire a closed character, but it is usually thinned out.
The huge variety of trees and interlayer plants determines the complex structure of the forest. The height of the tree canopy varies in different types of forest from 30 to 50 m, the crowns of individual trees rise above the general canopy, reaching a height of more than 60 m, these are the so-called emergent trees. The trees that form
the main canopy from its upper to lower boundaries is many, and therefore the tiers in the vertical structure are poorly expressed.
The shrub layer is practically absent. At the corresponding height, there are woody plants with a main trunk, the so-called dwarf trees, and tall grasses. Among the latter are species of herbaceous phanerophytes, i.e. herbs with perennial stems.
The grass cover of the humid tropical forest consists of representatives of two groups: shade-loving, living with a significant degree of shade, and shade-tolerant, normally developing in areas with sparse stands and oppressed under a closed forest canopy.
The structure of the forest is further complicated by numerous lianas and epiphytes, the vegetative organs of which are located at different heights.
Animal population. The fauna of tropical rainforests is as rich and diverse as the flora. Here, complex in territorial and trophic structure, saturated polydominant animal communities are formed. As with plants, it is difficult to distinguish dominant species or groups among animals on all "floors" of the tropical rainforest. In all seasons of the year, environmental conditions allow animals to reproduce, and although the reproduction of certain species may be associated with any period of the year, in general this process occurs constantly in the community. The polydominant structure of communities and year-round reproduction correspond to the smooth dynamics of the number of animals, without sharp peaks and falls.
In the structure of the animal community, one can clearly distinguish the soil, litter, and ground layers; above there is a series of tree layers passing into each other.
The abundance of animal tree tiers is provided by the mass of green fodder, the presence of a "hanging" layer of soil under the epiphytes and many "aboveground water bodies" in their rosettes, leaf axils, hollows and all kinds of depressions on tree trunks. Therefore, a variety of near-water and soil animals widely penetrate into the tree layers: crustaceans, millipedes, nematodes, leeches, and amphibians. According to the functional role in the biocenoses of the tropical forest, a number of leading trophic groups can be distinguished, some of them noticeably predominate in one or another layer of the forest. So, with the general abundance and diversity of saprophages - consumers of dead plant mass - the dominance of these animals is strongly expressed in the soil-litter layer, where leaf, branch and trunk litter is abundant, coming from all the higher layers. Various groups of phytophages - consumers of live plant mass -
distributed mainly in the middle and upper "floors" of the forest.
Termites are the leading group of saprophages in the rainforest. These social insects build nests both on the soil and on tree branches. The size of terrestrial termite nests in the forest is much less impressive than the well-known termites in the savannahs. Often, terrestrial termite mounds have a mushroom shape - a kind of roof that protects insects from daily tropical showers. Termites nests in trees are at the base of a thick branch near the trunk. Such a high placement of nests in termites is a protection against waterlogging. However, for any nest placement, the main food layer of termites is soil and litter. These layers are literally penetrated by their stern passages. They eat plant litter, dead wood, animal excrement and wood of growing trees. The digestion of fiber in the intestinal tract is carried out with the help of unicellular flagellates, which decompose it into simpler carbohydrates - sugars, which are absorbed by termites. The flagellates themselves, whose body weight is up to a third of the host's body weight, can exist only in the intestine of the termite. Termites, devoid of flagellates, cannot cope with the digestion of food and die. Thus, between termites and flagellates, a relationship of obligate (obligatory) symbiosis develops. In a humid tropical forest, the number of termite mounds per 1 hectare can reach 800-1000, and the termites themselves number from 500 to 10 thousand individuals per 1 m 2.
Various insect larvae (dipterans, beetles, aphids), adult forms (imago) of various small beetles, hay-eaters and aphids, larvae of herbivorous millipedes, and the kivsyak themselves are also involved in the processing of plant litter. Earthworms are also abundant in the litter. The tropical forests of South Africa and Australia are home to giant soil earthworms, reaching several meters in length, which are rare everywhere and are included in the International Red List of Protected Animals.
In the tree layer, phytophages are diverse: beetles, butterfly caterpillars, stick insects, gnawing leaf tissues, as well as cicadas,
sucking juices from leaves, leaf-cutting ants. A feature of the rainforest are anthills built from tree leaves, not only in the natural forest, but also on citrus, hevea, and coffee plantations.
Pollen and nectar of flowers, along with leaves, feed on adult forms of beetles: beetles, weevils, barbel. Many of them simultaneously act as plant pollinators, which is especially important in a closed forest canopy, where wind pollination is practically excluded.
Monkeys living on trees form a large group of consumers of green plant matter, as well as flowers and fruits of trees. In the African rainforest, these are brightly colored colobus, or guerillas, various monkeys. In the South American Gilea, plant food is consumed by large howler monkeys, in South Asia - langurs, gibbons and orangutans.
In the forests of New Guinea and Australia, where there are no monkeys, their place is taken by arboreal marsupials - couscous and arboreal kangaroos, and in Madagascar - by various lemurs.
Other representatives of the group of arboreal phytophages are two-toed and three-toed sloths inhabiting the forests of South America, fruit-eating fruit bats, which are widespread in the tropics of the Eastern Hemisphere.
In the humid tropical forests of South America, in the terrestrial layer, the largest herbivorous animal is the lowland tapir, whose weight reaches 250 kg. Here you can find peccaries outwardly similar to wild boars, as well as several species of small primitive spoke-horned deer-mazam. In the terrestrial layer of the South American gile, large rodents are common, ecologically replacing ungulates here. The capybara reaches the largest size (length up to 1.5 m, and weight up to 60 kg). These long-legged rodents keep in large herds, swim well and often graze on riverine boggy meadows.
The terrestrial layer of the African rainforest is inhabited by the gorilla apes. Their food is mainly bamboo seedlings, shoots of various herbaceous plants, less often the fruits of trees. Ungulates are not numerous in the African rainforest. Among them, the size of the brush-eared pig, the large forest pig, the bongo antelope and the pygmy hippopotamus are distinguished.
Birds of the rainforest, consuming plant food, inhabit all layers of the forest. Typical consumers of fruits in the African Gilea are turaco, or bananoed, from the cuckoo order.
Large, with a huge thick beak, often equipped with an outgrowth on top, hornbills are found in the tropical forests of the eastern hemisphere. They, like banana eaters, are bad flyers and
collect fruits from the terminal branches using a long, powerful, but hollow beak inside.
In the Amazonian gilea, a similar ecological niche is occupied by toucans from the order of woodpeckers. These birds also have a long and thick beak, but without outgrowths on the upper beak. Their main food is the fruits of trees, but on occasion they also eat small animals. Toucans nest in hollows abandoned by woodpeckers, or in natural hollows, but they do not hammer them themselves.
Large-legged, or weed, chickens inhabit the rainforests of Northern Australia, New Guinea and the islands of the Malay Archipelago. These birds almost never fly, keep under the canopy of the forest, collecting seeds, fruits and small invertebrates.
In the tropics of the Old World, small bright birds that feed on the nectar of flowers are common, they are sunbirds from the order of passerines. The Amazonian rain forest is inhabited by externally similar hummingbirds from the long-winged squad, distant relatives of swifts.
A variety of pigeons, which are usually green in color to match the color of the foliage, feed on the fruits and seeds of trees. There are many colorful parrots in the rainforest.
The dominant group of rainforest predators are ants, most of which mainly or exclusively feed on all kinds of animal food. Pronounced predatory ants belong to the subfamily of bulldog ants. The basis of their food is termites. Bulldog ants live in ground nests and actively protect them from any enemy. Constantly wandering, destroying all living things in their path, stray ants - dorilins. During the day they travel, and at night they interlock in a large ball, inside which are placed the larvae, pupae and the progenitor of the family - the female queen. Tailoring ants are common in Africa and South Asia. They build nests in the crown of trees from several green leaves glued together along the edges with a thin sticky thread. Ants get this thread from their larvae.
Amphibians in humid tropical forests inhabit not only terrestrial, but also tree layers, go far from water bodies due to high air humidity. Even their breeding takes place sometimes far from water. The most characteristic inhabitants of the tree layer are bright green, bright red or blue tree frogs, common in the Amazon and tropical forests of South Asia.
In South America, marsupial tree frogs live, the females of which carry their eggs in a special brood pouch on their backs. In Africa, where tree frogs are absent, as well as in Southeast Asia, copepod frogs are widespread. Some species are capable of gliding jumps up to 12 m in length due to the widely spaced membranes between the toes. In
All large regions of tropical forests are inhabited by legless amphibians - worms, slowly digging in the litter and soil in search of food. In South America and Africa, there are peculiar reptiles - legless and almost blind amphisbens, or two-walkers. Some of them (for example, the South American ibizara) settle in termite mounds or anthills and collect constant "tribute" from their population, and the special secretions of amphisbens reliably protect them from ants' bites. Lizards of the gecko family are most characteristic of the tree canopy of the tropical forest. Toes of geckos are equipped with extended discs with many microscopic hooks, with which these lizards easily cling to the surface of trunks and even smooth leaves.
Chameleons have developed peculiar adaptations to life in the forest canopy. There are especially many of these amazing animals in Africa and Madagascar. The sizes of chameleons are from a few centimeters to half a meter. According to the size, the diet of chameleons also changes: from ants, termites, small flies and butterflies to lizards, large cockroaches and even birds.
Large snakes that hunt rodents, reptiles, amphibians, and small ungulates live in the terrestrial layer of the humid tropical forest. The largest snake in the world, the anaconda, lives in the reservoirs of the Amazon, reaching a length of 5 - 6 m. Especially varied are the snakes of tree tiers, usually painted in different shades of green and completely invisible among the foliage. Tree snakes have a thin whip-like body, they skillfully disguise themselves, dying among the branches, becoming like vines or thin branches.
Birds consuming animal food in the rain forest occupy all its floors, especially in the upper, sparse tiers. Insectivorous birds belong to different families: flycatchers, drongoids and larvaeaters in the tropics of the Old World, trogons living on all continents, tyrannous and forest songbirds of South America. Raksha-like - kingfishers, bee-eaters are diverse in all regions. Some kingfishers are associated with water bodies and hunt for fish and other aquatic life, but many live away from water and feed on lizards, insects, and small rodents.
There are many in tropical forests and real birds of prey hunting large rodents, snakes, monkeys. A monkey-eating harpy lives in the forests of the Amazon, the name of which testifies to its food specialization. However, in addition to monkeys, this large, up to 1 m long, predator catches sloths, agouti, possums, and sometimes birds.
Among rainforest mammals, many species consume ants and termites. In African Gilea and Southeast
In Asia, they are eaten by pangolin, which is covered with large horny scales instead of wool. The wood anteater lives in the forests of the Amazon. These animals have powerful front legs with strong claws, with which they destroy the walls of termite mounds.
Large predators are represented by felines: in the Amazon it is a jaguar and an ocelot, in Africa and South Asia - a leopard. In the tropics of the Old World, representatives of the civet family are numerous - genets, mongooses, civets. All of them, to one degree or another, lead an arboreal lifestyle.
Thus, the animal population of humid evergreen tropical forests is extremely diverse, here representatives of different taxonomic groups in each of the three above-mentioned large regions convergently adapt to similar ecological conditions, forming a complex system of territorial and trophic relations.
Ecosystems of tropical rainforests in different regions, despite the sharp differences in the floristic and faunistic composition, are very similar in structure and represent the richest and most saturated communities within the Earth's biosphere. With a significant diversity of tropical forest communities, its biomass is represented by values of the same order of magnitude. It is usually in primary forests 350 - 700 t / ha (mountain humid tropical forests of Brazil), in secondary - 140 - 300 t / ha. Of this biomass, the most significant in comparison with the biomass of all land communities, the predominant part falls on the aboveground plant organs, mainly trees, and the least on the root systems. The main part of the root systems of trees is located in the soil at a depth of 10 - 30, rarely more than 50 cm. The leaf area ranges from 7 to 12 hectares per hectare of soil surface. The values of the annual production vary greatly in different types of forest. Net production can be 6 - 50 t / ha, or 1 - 10% of biomass.
Despite the apparent abundance of animal organisms, the latter constitute an insignificant part of the total biomass, about 1000 kg / ha, or 0.1% of its reserves, and, like in temperate forests, earthworms make up about half of the zoomass.
Humid rainforests, although they have a strong and balanced structure, are easily destroyed by anthropogenic impact. On the site of a cleared tropical forest, secondary forest communities appear, which significantly differ from the indigenous ones in species composition and are inferior to them in biomass, productivity and structure complexity. It takes several centuries to restore the primary forest in favorable conditions.
Have you adapted to his bathing conditions?
How did the leaves adapt?
Throughout life, the leaves of some tropical plants change shape. In young trees, while they are still covered by the crowns of the upper tier trees, the leaves are wide, soft. They are adapted to catch the slightest rays of light breaking through the upper canopy. They have a yellowish or reddish tint. So they try to escape from being devoured by animals. Red or yellow may seem inedible to them.
When the tree grows to the first tier, then its leaves decrease in size and seem to be covered with wax. Now there is a lot of light and the leaves have a different task. The water should completely drain from them, without attracting small animals.
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The leaves of some plants can regulate the flow of sunlight. In order not to overheat in bright light, they stand parallel to the sun's rays. When the sun obscures the cloud, the leaves turn horizontally to take up more solar energy for photosynthesis.
Pollination of flowers
For pollination, flowers must attract insects, birds, or bats. They attract with their bright color, smell and delicious nectar. Even the top-tier plants adorn themselves with beautiful flowers to attract their pollinators. Moreover, during flowering, they even shed some of their leaves so that their flowers stand out more noticeably.
Orchids secrete nectar to attract insects, from which the bees get drunk. They are forced to crawl over the flower, pollinating it. Other orchid species simply slam shut, sprinkling pollen on the insect.
But it is not enough to pollinate the flowers, it is still necessary to spread the seeds. Seeds are carried by animals. To attract them, the plants offer them tasty fruits with seeds hidden inside. The animal eats the fruit, and the seed comes out of it along with the excrement, quite capable of germination.
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Sometimes plants reproduce with only one species of animal. So the American walnut reproduces only with the help of a large rodent agouti. Although agouti nuts are eaten completely, they bury some of them in the ground. Our proteins also make such a reserve. Forgotten seeds sprout.
Eating animals in the tropics
There is not enough food for animals among the abundance of food. Plants have learned to defend themselves with thorns, poisons, and bitter substances. Over the years of evolution, animals have found their own way of adapting to living in tropical forests. They live in a certain place and lead the life that ensures his survival.
It happens that a predator eats beetles of a certain species. He learned to catch beetles quickly, spending a minimum of time and effort on hunting. The predator and its prey have adapted to each other. If the beetle does not become, then the predator that eats them will also die out.
Adaptation of animals to habitat in the subtropics
In the tropics, food grows and flutters all year round, but it's not enough. All conditions have been created for invertebrates in the forest, and they grow to large sizes. These are centipedes, snails and stick insects. Mammals are small. There are few herbivores in the forest. There isn't enough food for them. It means that there are few predators feeding them. There are no animals with long horns. It is difficult to navigate the tropics with them. Mammals move quietly. Thus, they are saved from overheating.
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Nimble monkeys live well in the tropics. They move quickly through the forest, looking for places where a lot of fruit has grown. The monkey's tail replaces the fifth limb. The anteater and the needle-hair porcupine also have a grasping tail. Animals that cannot climb well have learned to fly well. They plan easily. They have a leathery membrane that connects the front and hind legs.
Union of a tree with ants
In the tropics, trees grow with hollow branches. Ants live in the cavity of the branches. They protect their tree from herbivores. Ants give the tree enough light. They gnaw on the leaves of the vines in nearby trees, blocking the light for their host tree. The ants eat all the leaves that do not look like the leaves of their native tree. They even remove all organics from its crown. The tree is well-groomed, like a gardener. For this, insects have dry shelter and safety.
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How did the frogs adapt?
High air humidity allows toads and frogs to live far from the river. They live well, living in the upper tiers of the forest. For the reservoir, the frogs chose tree hollows. They smear it with resin from the inside and wait for it to be filled with rainwater. Then the frog lays eggs there. Dart frogs, arranges holes for their offspring in wet ground.
The male remains to guard the clutch. Then it transfers the tadpoles to the formed reservoir, formed between the leaves of bromeliads. Some frogs lay their eggs in a foam nest. They sculpt a nest on the branches hanging over the river. The hatched tadpoles immediately fall into the river. Other frogs lay their eggs in damp ground. They emerge from there as young individuals.
Animal disguise
Animals in the forest try to become invisible to their predators. There is a constant play of light and shadow under the forest canopy. Such spotted skins are found in okapis, antelopes, bongos. The mottling blurs the contours of their bodies and makes them difficult to distinguish. You can very well disguise yourself as leaves. If the animal looks like a leaf and does not move, then it is difficult to see it. Therefore, many insects and frogs are green or brown in color. In addition, they do not move much. And stick insects disguise themselves as a twig.
