Balance in an ecosystem is extremely important to ensure proper nutrient flow through food. In a healthy ecosystem, the foodchain is a pyramid. Species in the lower trophic levels exist in large numbers and provide food and nutrition to those in higher levels. The higher level species keep the lower level population from growing uncontrollably through predation. Those in higher levels have smaller population (because one predator needs many preys to survive) and their population is controlled through limitation of food source. This control mechanism is the key to any healthy ecosystem.
Apex predators sit at the top of the foodchain. By controlling prey population, they control the integrity of the entire ecosystem. Loss of the apex predator is one of the biggest challenges facing many national parks in the world right now. Some national parks like Yellowstone in US have already faced the consequences of complete loss of the apex predator, grey wolves. The only option to stop a complete ecosystem collapse was to reintroduce wolves in Yellowstone.
The threats are similar for tiger reserves in India as well. We should take all possible measures to save these beautiful apex predators before it's too late. In Yellowstone, it was possible to reintroduce wolves by translocating them from other regions. With less than 3000 wild tigers in India left, we may not even have that luxury.