Bangalore needs the right kind of trees

“Plant a tree”: It’s the favourite adage on a placard. The motto for us — abruptly awakened self-confessed earth saving warriors. That’s all you need to do to — stick a band aid on the rather small gash we’re causing the environment: Plant a tree. If only it were so easy.

Among the complications surrounding planting trees is the crucial question of what kind of trees does a city like Bangalore require. Anything that sprouts leaves won’t do.

“I’ve seen bushes and shrubs like bougainvillea along the ring road,” says Dr Harini Nagendra, an urban ecologist with disapproval. “This just won’t help. It might look green, but it’s doing us no good,” she adds. Nagendra has published a research paper Street trees in Bangalore: Density, diversity and composition and distribution, where she explains that while the city has a high diversity in trees, the density of trees is very poor as compared to other cities.

But the way things are going, even the diversity is persistently reducing. Older trees such as raintrees, African tulips, Delonix regia (gulmohar), copper pods and tabebuia are being replaced by trees with smaller canopies such as mast trees, millingtonia and bushes. When trees with huge canopies are felled (most of these trees can be 80 to 150years old), replacing them with a few saplings (that too of the wrong kind) hardly compensates for the loss. The older trees around Bangalore, though some are not native species (like the raintree), have adapted well to the city. Another criterion in choosing trees is to remember that trees are also habitats and a variety of urban wildlife (small mammals, bees, insects, butterflies and birds) depend on them. So a lot of thinking needs to go into planting trees, cautions Dr Siddappa Setty from Ashoka Trust for Research in Ecology and the Environment (ATREE).

Considering urban wildlife, flowering and fruit-bearing trees must be chosen, he says. And there has to be a good mix of these trees. Species we can choose from could include sampige, mango, thespisea, beete, paarijaatha, neem, gasagare and ficus (fig), he says. The fig tree is a keystone species and a single fig fruit can have as many as 50 to 100 different insects inside it he says. With the wrong kind of trees, there is a grave danger of losing our pollinators and soon we’ll be caught in a vicious web of destruction.

Setty adds, “we need to choose indigenous species.” They withstand heavy rains and we won’t find as many trees uprooted and broken after a heavy downpour. We also need to pick trees with deeper roots than lateral roots as they are likely to be sturdier, says Setty.

Janet Yegneswaran from the “trees for free” campaign has planted 24,300 trees in the city since 2005. Her choice of saplings include native species and a lot of fruit-bearing trees. Jamuns, mangoes, sampige or champak, lime, sapota neem, pongamia, tamarind, ficus etc figure in her planting list. Near residential colonies a favourite pick is Singapore cherry. In the outskirts she says picking fruiting trees gives farmers a chance to earn extra revenue.

Post-planting care is another vast topic. Nagendra points out that cattle guards are essential and those in the neighbourhood must be encouraged to take care of trees. “Unless we’re sure someone’s around to take care of the tree, we don’t plant trees,” says Yegneswaran.

While we need to plant trees, what we also need is a good tree policy, emphasises Nagendra. “We keep hearing about saplings being planted for the trees felled, but where are these trees being planted? What are the trees being planted?,” she asks. And honestly, to think a sapling can replace a 150 year tree, the shade and the shelter it provides is sheer foolishness, she reminds.