Lantana (Lantana camara) has become one of the world’s most invasive weeds. Shonil Bhagwat and others analyze the history of lantana invasion and management in India, Australia and South Africa. These are the highlights from their study published in the journal PLoS One, summarized for Conservation India by Krithi K. Karanth.
- The authors examined 75% of known historical records for the species in India, Australia and South Africa.
- Aggressive extermination measures taken by the government over the last 200 years have largely failed. These measures include fire, mechanical, chemical, biological and combinations of these approaches.
- Lantana continues to spread and occupies 13 million hectares in India, 5 million in Australia and 2 million in South Africa
- Post war land use change is speculated to be possible trigger.
- Most studies of lantana are short (< 1 year) and there is a major need to understand this species over a longer time period.
- Paper recommends an adaptive management approach to curtail the spread of this species as opposed to aggressively attempting eradication.
The authors compiled 1672 records from forestry and land management reports from the 1800s to the present day. Additionally, in India forestry working plans, forest department reports and records from the Indian Forester were collated. Records were scored from 1-7 for severity with 7 being the most severe.
- Early invasion of lantana is recorded for towns and cities; it subsequently spread to the countryside.
- Lantana is highly adaptable, growing in a wide range of habitats from sea level to mountains, rainfall areas from 1000-4000mm/yr, and hinders seedling growth of other plants.
- Lantana has invaded all three countries but the time of invasion is different: India 1800s, Australia before 1850 and South Africa after 1850.
- The recognition of lantana as a weed occurs later and the need for management arises in the 1920s in India and Australia and in the 1950s in South Africa.
- Control measures include fire, mechanical, chemical, biological and combinations, with combinations used most commonly in India, biocontrol used in Australia and mechanical used in South Africa.
- Lantana eradication and management has become very expensive globally. Costs of control are US $200 per hectare in India. Laws have been enacted in several countries to restrict import, sale or distribution of lantana, and support eradication.
- Lantana has both positive and negative impacts on ecosystems. Impacts include ability to hinder some and increase regeneration of some species, increase water run off and decrease or increase soil erosion. It has been documented to provide cover and food for some wildlife and livelihood benefits to local communities (handicrafts, paper, furniture).
- Increasingly, lantana is being managed not eradicated.
Long-term monitoring studies on Lantana needed
Lantana is here to stay. The hard lessons learnt from costly and largely ineffective eradication efforts suggest that perhaps we need to adaptively manage the species. This requires long-term studies (> ten years) conducted across space under a variety of conditions. Perhaps it is better to recognize the functional role of this species and manage it accordingly.
Bhagwat SA, Breman E, Thekaekara T, Thornton TF, Willis KJ (2012) A Battle Lost? Report on Two Centuries of Invasion and Management of Lantana camara L. in Australia, India and South Africa. PLoS ONE 7(3): e32407. doi:10.1371/journal.pone.0032407