IAS General Studies Prelims Question No. 98

A rainforest once destroyed is almost impossible to recover. What is / are reasons of such problem?
1. The soil in the tropical rain forest floor is devoid of nutrition
2. The tropical rainforests cannot regenerate under many current land-use practices
3. The tropical rainforests thrive in natural conditions under internal complexity and interdependence
Choose the correct option from the codes given below:
[A] Only 1 & 2
[B] Only 2 & 3
[C] Only 1 & 3
[D] 1, 2 & 3
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[D] 1, 2 & 3
A rainforest cannot be replaced. Once it is destroyed it is gone forever (almost thousands of years). Here are a few observations:
Nutrient Deficient Soil
Only the top few inches of rainforest soil have any nutrients. Below that it is deficient in nutrients. There is a high temperature and this high temperature leads to decomposition of the organic material as well as the inorganic parent material of the soil. There are frequent rains and these rains leach the decomposing material off the soil, out of the root zone quickly. So, the result is that the Tropical rain Forests have adapted themselves and quickly take up the nutrients and most nutrients in the tropical rain forests is stored in the vegetation. When the forest is harvested for timber or other plant products, or the forest is burned, nutrients will be lost from the ecosystem, but the outputs cannot exceed inputs for very long because the stock of nutrient capital in the system will be depleted. When forests are burned, or the cut timber is removed as in logging, the nutrients that were in the tree biomass are either washed out in the case of burning or simply removed from the system. Because there was only a small stock of nutrients in the soil and most of the nutrients were in the biomass, there is little nutrient stock remaining to support regrowth. Thus, we can’t simply “regrow” tropical forests once they are burned — once they are lost they are gone forever (or at least for 1000s of years, and even then the species that regrow will be different from the original forest species).
Internal Complexity
Although tropical rainforests can regrow under natural conditions, where clearings are caused by floods, storms, or treefalls, they cannot regenerate under many current land-use practices. Forests regenerate poorly if at all when large areas are logged, the soil is damaged or removed, or erosion is severe. Rainforest ecosystems are vulnerable to disruption because of their internal complexity and interdependence. Because there are few individuals of any one species, removal of even small numbers of them has a substantial effect on species composition and interrelationships in the forest by depressing reproduction, and long periods of time will be required to reconstruct viable populations. Forests are also dependent upon their closed nutrient cycles; disruption of these cycles by exposure and extraction of trees can cause their destruction. If the land has been cleared for a long period of time, reforestation occurs slowly or not at all, due to the lack of suitable seeds and seedlings, increased ground temperatures, decreased humidity, and the like.



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