The rise in Tahr numbers in Eravikulam National Park has had both positive and negative impacts on the ecosystem. Here are the key points:

• The increase in Tahr populations has benefited the overall biodiversity of the park, as they are an important prey for predators like leopards and tigers.
• Tahrs help maintain grasslands by grazing on certain areas, preventing them from becoming overgrown and promoting growth in other areas they don't forage on.
• However, the overgrazing of certain areas by Tahrs can lead to soil erosion and soil nutrient depletion which can affect the quality of the grasslands.
• Their increased population has also led to competition for resources. As Tahrs compete not only amongst themselves but also with other herbivores like Sambar deer.
• Furthermore, the increase in Tahr populations has also led to an increase in the population of their predators, causing a shift in the predator-prey balance. This shift can be harmful if not managed properly.

Overall, while the rise in Tahr numbers has positive aspects, it's important to monitor their populations and grazing patterns to ensure the ecosystem stays healthy.