Rising temperature, changing rainfall pattern may have affected growth of plants essential to native ecosystem
The Malabar pied hornbills feed on fig, whose fruiting has been impacted due to the changing climatic conditions. Photo: UdayKiran28 / Wikimedia Commons The Dandeli forest in Uttara Kannada district of Karnataka is known for its forest grasses, birds and cattle herders. In recent years, rising temperatures and changing rainfall patterns are impacting the forest ecosystem and the people living around them and dependent on them.
There are around 100 different types of grasses that grow in the undergrowth of the Dandeli forest, according to a survey published by scientists from the Centre for Ecological Sciences of the Indian Institute of Science, Bengaluru. These are the primary sources of food for the herbivore population of the forest such as barking deer, chital (spotted deer) and elephants.
“Around 30 years ago, there were good undergrowth of grasses in the area but they have become scarcer in recent years,” GE Umesh, a local wildlife expert and photographer, told Down To Earth (DTE).
The grasses are being replaced by eupatorium weed, which is not eaten by the herbivores and is prone to fires. Umesh surmised that this is happening due to changing rainfall patterns in the area and generally rising temperatures.
The main indication of generally rising temperatures is the advent of air conditioners in the area, which were rare a decade or so ago, according to Umesh.
“In some years there is rainfall throughout the year and in others there is no rainfall for 4-5 months and there is also more rain in the winter season,” said Umesh.
“The grasses in the Dandeli area proliferated mainly during the colonial era when the lush semi-evergreen and evergreen forests were replaced by monoculture teak plantations and general character of the forest also changed from semi-evergreen to moist deciduous,” MD Subash Chandran of the Centre for Ecological Sciences, Indian Institute of Science, told DTE.
“In the span of 14-15 years, we lost evergreen pockets of forest in Dandeli. Moist deciduous forests have now been converted into dry deciduous forests,” said Umesh.
The British, during their rule, had banned controlled fires in the forest, which was practiced by local farmers for slash and burn cultivation. This, in turn, led to there being uncontrolled forest fires. This is because dry leaves, tree limbs and other inflammable debris would be removed during controlled fires, limiting the chances of wildfires.
These uncontrolled blazes have become more frequent now with the spread of eupatorium, a non-native species introduced in the area during the British rule for decorative purposes, as well as general increase in dryness during decreased rainfall years, according to Chandran.
Chandran, an expert on the ecology of the Western Ghats, added that the changes induced by the British are now being exacerbated by climatic changes and fragmentation due to human interventions. This has changed the fundamental character of these forests and the animals and the people who call them their home.
“The impact on the grasses is now reducing the herbivore population in the area though we do not know by how much,” said Umesh.
The herbivores are the main prey base for big cats such as leopards and tigers. As they started decreasing in numbers the cats started preying on the cattle of the local herders.
“A lot of wild predators have been entering our village in the recent years, which has increased instances of our conflict with them,” said Bommu Biru Yedage from Adikehosur village of Haliyal taluk, Uttara Kannada district, that lies on the fringes of the Dandeli forest.
"When there were a good amount of grasses in the forest and the villagers could herd their cattle within them, there would be 40-50 cattle per household. But now that has reduced to 4-5 per household,” said Umesh. This is because of both the loss of grasses and the focus of the leopards and tigers shifting to the easier prey base of local cattle. The main cattle-herding community in the area is the Gavli pastoral tribe.
Some other fundamental ecological processes, such as the flowering and fruiting patterns of the more than 40 different varieties of fig trees that grow in Dandeli, have changed. The fig fruits are the main source of nutrition for most of the local birds in the area, especially the Malabar pied hornbill. Some migratory birds such as flycatchers also eat these fruits.
“The fig trees are not fruiting properly and the ripening of the fruits is also not up to the mark. The hornbill birds that this area is famous for also feed on figs and they have been abandoning their nests in the past 4-5 years,” said Umesh, who has been photographing a specific hornbill nest for the past two decades. It now lies abandoned, informs Umesh.
Honey collection in the area has reduced in recent years as the ficus trees are not flowering properly.
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