Nearly half of the native plant species in the city’s wetlands have been wiped out in recent years, indicative of the degradation of wetlands, finds a study done by the Care Earth Trust, a biodiversity research organisation.
Retteri or Madhavaram lake and Pallikaranai marshland are among the worst affected wetlands in the city. About 60% of the plant species have been overrun by invasive species in the past two years.
The study observed the native plant species found in the wetlands of Sembakkam, Ambattur, Perumbakkam, Narayanapuram, Thalambur, Korattur, Madhavaram and Pallikaranai marshland for two years.
The invasive species have faster growth rate than the natives, said N. Muthu Karthick, team leader (research), Care Earth Trust. Some of the indigenous plants have medicinal value. The once commonly seen native plants have now diminished, he said.
According to the study, the indigenous species are being replaced by invasive and destructive ones. “The rapid depletion in indigenous aquatic plants would prove detrimental to the functions of the wetlands. The decline in indigenous flora would also have indirect implication on food and nutrition security,” Mr. Karthick cautioned.
‘Further study needed’
Jayshree Vencatesan, managing trustee, Care Earth Trust, said the Sembakkam lake is rich in native aquatic plants and this could be due to its proximity to Nanmangalam reserve forest. “We need to research the role of water bodies and reserve forest in biodiversity conservation,” she said.
Identifying the invaders and using species-specific methods to remove them periodically could mitigate the depletion of native plant species from the wetlands. Reintroducing native species in vulnerable habitats could also help, the study noted.