Deforestation

Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use.

Deforestation occurs for many reasons: trees or derived charcoal are used as, or sold, for fuel or as timber, while cleared land is used as pasture for livestock, plantations of commodities, and settlements. The removal of trees without sufficient reforestation has resulted in damage to habitat, biodiversity loss and aridity. It has adverse impacts on bio-sequestration of atmospheric carbon dioxide. Deforested regions typically incur significant adverse soil erosion and frequently degrade into wasteland.

Disregard or ignorance of intrinsic value, lack of ascribed value, lax forest management and deficient environmental laws are some of the factors that allow deforestation to occur on a large scale. In many countries, deforestation, both naturally occurring and human induced, is an ongoing issue. Deforestation causes extinction, changes to climatic conditions, desertification, and displacement of populations as observed by current conditions and in the past through the fossil record.

Basic Knowledge of Tropical Rainforest

A tropical rainforest is a place roughly within 28 degrees north or south of the equator. They are found in Asia, Australia, Central America, Mexico and on many of the Pacific Islands. The rainforest is humid. Tall, broad-leaved evergreen trees are the dominant plants, forming a leafy canopy over the forest floor. Taller trees, called emergents, may rise above the canopy. The upper portion of the canopy often supports a rich flora of epiphytes, including orchids, bromeliads, mosses, and lichens, who live attached to the branches of trees. The undergrowth or understory in a rainforest is often restricted by the lack of sunlight at ground level, and generally consists of shade-tolerant shrubs, herbs, ferns, small trees, and large woody vines which climb into the trees to capture sunlight. The relatively sparse under story vegetation makes it possible for people and other animals to walk through the forest. In deciduous and semi-deciduous forests, or forests where the canopy is disturbed for some reason, the ground beneath is soon colonized by a dense tangled growth of vines, shrubs and small trees called jungle.

The rainforest is divided into five different layers and they are the emergent layer, canopy, understorey layer, shrub layer and forest floor.

The emergent layer contains a small number of very large trees which grow above the canopy layer, reaching heights of 45-55 m, although on occasion a few species will grow up to 40 m or 50 m tall. They need to be able to withstand the hot temperatures and strong winds. Eagles, butterflies, bats and certain monkeys inhabit this layer.

The canopy is the primary layer of the forest and forms a roof over the two remaining layers. Most canopy trees have smooth, oval leaves that come to a point. It's a maze of leaves and branches. Many animals live in this area since food is abundant. Those animals include: snakes, toucans and tree frogs.

Little sunshine reaches the understorey layer, so the plants have to grow larger leaves to obtain sufficient sunlight. The plants in this area seldom grow to 3 m (10 feet). Many animals live here including jaguars, red-eyed tree frogs and leopards. There is a large concentration of insects here.

The shrub layer and forest floor are very dark. Few plants grow in this area, as a result. Since hardly any sun reaches the forest floor things begin to decay quickly. A leaf that might take one year to decompose in a regular climate will disappear in 6 weeks. Giant Anteaters live in this layer.

Climbing Ferns and Ephiphytes

Other plants with clever adaptations that use tall trees to get up to the light are climbing ferns and epiphytes. Some of the climbing ferns found in Australian tropical rainforest biomes are Slender Cucumber (Zehneria cunninghamii) and Coarse Climbing Fern (Lygodium reticulatum). Epiphytes such as Birds Nest Fern (Asplenium australasicum) and Northern Elkhorn (Platucerium hillii) don’t even have to climb. They start growing high up on tree trunks as little plants, when birds drop their seeds there. Some epiphytes, like strangler figs (as mentioned above) start growing their roots down until they reach the ground. The host tree is by then killed and the fig tree can lean on its dead trunk, while it would be too weak yet to stand so high up on its roots. By the time the dead tree trunk weakens as it starts rotting, the fig tree roots are strong enough that it can stand by itself. There are many such stangler figs in Australian rainforests, but some of the most famous ones are Curtain Fig Tree and Cathedral Fig Tree onAtherton Tablelands.

Vines and Lianas

Creepers, vines, and lianas (woody vines) are abundant in the canopy and make up a significant proportion of the vegetation in tropical rainforests. There are over 2,500 species of vines from about 90 families [liana distribution]. They range from small, indiscrete vines that grow against the tree to giant lianas thick as trees that seemingly hang in the middle of the forest independent of trees. Some of the larger woody lianas may exceed 3,000 feet in length. Rattan, a liana, is well known for its use in furniture and ropes. Rattan also produces large, edible fruits—a favorite of primates.

Lianas are vines that begin life on the ground as small self-supporting shrubs and rely on other plants to reach the light-rich environment of the upper canopy. Because lianas use the architecture of other plants for support, they devote relatively little to structural support and instead allocate more resources to leaf production and stem/root elongation for rapid growth. Since lianas are rooted throughout their lives (unlike other structural parasites like epiphytes and hemiepiphytes), they take nothing from the tree except support. 

Basic Knowledge of Monsoon Forest

Monsoon Forest are open woodland in tropical areas that have a long dry season followed by a season of heavy rainfall. The trees in a monsoon forest usually shed their leaves during the dry season and come into leaf at the start of the rainy season. Many lianas (woody vines) and herbaceous epiphytes (air plants, such as orchids are present. Monsoon forests are especially well developed in Southeast Asia and are typified by tall teak trees and thickets of bamboo.

Maximum tree heights range from 40 to 100 ft (12 to 35 m), which is less than in the equatorial rainforest. Many tree species are present and may number 30 to 40 species in a small tract. Tree trunks are massive; the bark is often thick and rough. Branching starts at comparative low level and produce large round crowns. Perhaps the most important feature of the monsoon forest is the deciduousness of most of the tree species present, e.g. the abundance of tropophytes. The shedding of leaves results from the stress of a long dry season, which occurs at time of low sun and cooler temperatures. Thus the forest in the dry season has somewhat the dormant winter aspect of deciduous forest of middle latitudes. A representative example of a monsoon forest tree is the teak wood tree