Context

• Invasive ornamental shrub, Lantana Camara is altering traits to spread across Indian forests.

Lantana Camara

• Lantana camara is a species of flowering plant native to the American tropics.
• It was introduced in India as a decorative shrub during the British colonial period but turned out to be an invasive plant.
• It is a very adaptable species, and can inhabit a wide variety of ecosystems.

Invasive Alien species

• Any non-native species that significantly modifies or disrupts the ecosystems it colonizes is referred to as invasive in nature.
• Common characteristics include 
  • Rapid reproduction and growth
  • High dispersal ability, 
  • Phenotypic plasticity (ability to adapt physiologically to new conditions), and 
  • Ability to survive in a wide range of environmental conditions.

Recent Findings

• The “India State of Forest Report 2021”, states that more than 9,793 sq km is under lantana in 1997, some 96 per cent of the Western Ghat reserve was under native flora, while 4 percent was under lantana. 
• By 2018, the area under native flora had shrunk to 53 percent, while lantana occupied 47 percent of the reserve.
• Wildlife Institute of India, Dehradun, surveyed 207,100 sq km of forests in 18 states and found the weed across 86,806 sq km.

Changing Character of Lantana

• Lantana primarily invades open, well-lit environments and avoids less sunlit areas. 
• It is also known to exhibit adaptive modulations for proliferating heterogeneous environments like grasslands, farms and rural and urban settings.
• Lantana have high phenotypic plasticity, which is the ability to alter physical traits when exposed to different environmental conditions. 
• Lantana species that grow in the shade, for instance, reproduce through vegetative propagation (a process in which plants reproduce from stems, roots, leaves and other parts). 
• This allows them to spread across the forest floor or climb closer to the crown of the trees. In well-lit areas, the same plant uses seeds to propagate. 
• Lantana plants in the shade also have greater distance between the nodes (the location on a stem to which a leaf or branch is attached) and larger leaves when compared to those found in well-lit areas.

Major threats 

• Lantana restricts the diversity of native species and poses a threat to the forest ecosystem. 
• The plant also reduces soil fertility by uptaking water and nutrients faster than the native species.
• It transforms the soil structure and micro environment to their advantage by producing chemicals which cause threats to biodiversity.
• It results in failure of regeneration of forest.

Cut Root-stalk Method

• Currently, the country uses the “cut root-stalk” method to get rid of lantana bushes. 
• In this method, the aim is to chop down the main stem 2-3 cm below the ground.
• The plant is placed upside down and this creates a hormonal imbalance, so no new roots are produced and the lantana dries up.
• However this method has not been very successful as the remains of the root system of the plant persist in the soil, and as soon as the plant gets favorable conditions, it regenerates.
• Further, it is an expensive, labour-intensive and time-consuming method.

Way forward

• A comprehensive survey should be conducted by the Forest Department to identify the area and density of the spread of invasive species in wildlife sanctuaries, National Parks and Protected Areas.
• Adequate time and budget should be allocated to handle this herculean task.