Senna Spectabilis Invasion-South Indian Forests are threatened

Uncontrolled proliferation of the South American introduced tree Senna spectabilis has become a critical ecological problem in South India. Its overgrowth outmuscles indigenous vegetation, changes the composition of the soil, and interferes with the habitat of wildlife, especially in the Nilgiri Biosphere Reserve.

Ecological Impact

This invasive tree develops thick sterile masses that inhibit the growth of grass and shrubs necessary to support herbivores such as deer and gaur. Due to this, the large mammals like the elephants and tigers are forced to come close to human settlements worsening the conflict. Senna now covers more than 40 percent of the forest in Wayanad Wildlife Sanctuary, compared to 23 percent in 2021.

Eradication in Wayanad

Kerala has introduced the first science based and community based eradication programme in India in the Tholpetty range of Wayanad. Approximately 383 acres of forest were cut and more than 46,000 trees were uprooted with a specially designed machine that allows removal of roots completely. This effort was largely a central responsibility of tribal youth of Kurichiya and Kattunaikka communities.

Signs of Recovery

The deforested sites are naturally recovering with the reappearance of grasses, herbs, and more than 80 re-planted native tree species. The bird population has increased and elephants are returning to areas that were left long ago and this shows how the eradication strategy is working.

Challenges Ahead

As each tree bears thousands of seeds that have a shelf life of up to 10 years, total elimination is quite a challenge. Constant checking and destruction of seedlings is necessary. States such as Karnataka and Tamil Nadu are currently looking to follow in the footsteps of Wayanad, and look into commercial applications of removed biomass.

Wider Lessons

The conquest of Senna spectabilis highlights the wider problem of invasive plant species such as Lantana, Eupatorium and Acacia in India. The Wayanad project shows the value of taking early action, science, and community in rebuilding native biodiversity and conserving delicate ecosystems.