Rampant exotic plantations have reduced avian diversity across Pune: study
According to a recent study conducted by researchers of the department of Zoology from Savitribai Phule Pune University (SPPU), avian diversity has been reduced in the city to rampant exotic plantations.
The study found that original vegetation on the hill of Pune city is home to 86 bird species as compared to the exotic plantation where only 38 bird species are found. The study also revealed that 14 migratory bird species were seen in original vegetation as compared to only four migratory species in exotic vegetation across Pune city.
The paper regarding the same was published on May 2 by researchers from Pune in the ‘Tropical Ecology’ by Springer Journal.
The study further revealed that exotic plantations have the lower richness and high dominance of woody plant species compared to savanna patches. Currently, original vegetation to the hills in Pune city are under threat of non-scientific plantation forestry, therefore awareness among citizens, policymakers, forest officials are necessary for its conservation, said researchers.
Kiran Choudaj, PhD student at department of Zoology at SPPU said that he decided to work on this topic for his PhD thesis and started exploring different reasons for the decline in the number of bird species in exotic plantations.
“I carried out work for two years (2017-2019) over the five hills in the city, that are, Chaturshringi, Vetal, Bavdhan reserve forest, Pashan-Baner, Pachgaon-Parvati (Taljai tekdi).
During this study, we observed a total of 86 bird species in savanna patches and 38 bird species in exotic plantations. Grassland birds such as Jungle Bush Quail, Jacobin Cuckoo, Shrikes, Indian Roller, White-bellied Minivet, Pipit, Rosefinch, Buntings were absent in exotic plantations. Higher percentage of omnivore birds while lower percentage of predator and herbivore bird species were seen in exotic plantations, as compared to Savanna vegetation,” said Choudaj.
He further added that the study observed that there were only four migratory bird species in exotic plantations which was found to be very less as compared to 14 bird species which were seen in original vegetation.
“In exotic plantations, Gliricidia (Gliricidia sepium), African Blackwood (Dalbergia
melanoxylon) and River Tamarind ( Leucaena leucocephala) were the abundant exotic plant species present. Gliricidia was the most dominant and densely planted species over savanna vegetation. Its allelopathic secretions have herbicidal and insecticidal activities which have reduced grass and herb cover which was present before in those regions. River Tamarind also secretes allelopathy secretions and is regarded as one of the world’s worst invasive plant species. Thus, due to the decrease in the grass-herb cover there is a decrease in the animals that are dependent on it, ultimately leading to decrease in the bird species,” said Choudaj.
The guide to the study, Varsha Wankhade, associate professor with the department of Zoology at Savitribai Phule Pune University (SPPU) said that common citizens perceive the savanna patches as of low conservation value compared to the plantations.
“One key reason is that the citizens think that these savanna patches are manmade and thus not ancient. The citizens believe in the myth of existence of a ‘thick forest’ sometime back in history, which was degraded by humans and now we get the savanna patches. Emerging research shows that savanna patches are not ‘degraded forests’, savannas existed even before humans started using them. Global and Pune savannas is quite ancient. These remnant savanna patches are slow to recover once destroyed by plantations. Destroyed savanna patches require at least a century or more of time to recover their plant species richness in that case weedy plant species have the ability to thrive in recovering savanna but some of the savanna species may not recover easily. This implies that little savanna patches which have been left must be preserved at any cost and to conserve these patches some of the savanna specialist birds should be used as mascots,” said Wankhade.
She added that birds like the Yellow-wattled Lapwing and White-bellied Minivet can be used as canvas for saving these grassy patches.
“Awareness and sensitization about these grassy habitats among citizens, planters, managers and policymakers are necessary for the conservation of these unique habitats,” said Wankhade.
Kiran Choudaj and Varsha Wankhade published one more article in the journal of Threatened Taxa, titled ‘Changed avian assemblage of Savitribai Phule Pune University (SPPU) campus in the last four decades.
“In this study, we tried to assess the bird diversity of the SPPU campus and Khadki pond which is adjacent to campus in two time periods 1976 and 2018. In 2018, we failed to notice 34 bird species out of 90 bird species listed for campus and pond in 1976. A major reason for the decline in bird diversity is due to changes in the campus habitat from low scrub jungle, fallow lands and grassland to buildings, roads, and exotic plantations. Increased human settlement surrounding the campus is also one of the contributing factors for the decline in bird species on the campus. Khadki pond was a perennial pond, now transformed into the seasonal pond that has been overtaken by natural vegetation due to blockage of water channels,” said Choudaj.