Have you ever seen anyone digging with their gardening shovel in the forest or a preparing a seedling germination tray in the woods? Who then plants the teeming and endless variety of vegetation? Forests have their own expert gardeners who carry and spread seeds far and wide, keeping it alive and growing.
In fact, 95 percent of tropical rainforests depend on animals to disperse seeds. Seeds that fall under their ‘parent trees’ are prone to predation, fungal attacks and competition from the bigger tree. But with a little help from wildlife they can make it to safer growing grounds.
Here are some master-horticulturists from the animal kingdom who make that happen.
These large plant loving pachyderms are the planet’s best gardeners. They forage and eat up to 150kg of food made up of shoots, leaves, twigs, barks and lots of fruits from a large variety trees each day. In turn, they scatter seeds of important tree and plant species across a wide area. Their massive size enables them to eat fruits too big for other mammals too, reach high hanging fruits and importantly transport them through vast distances.
Some tree species depend exclusively on these massive mammals for their dispersal. While the Asian elephant spreads seeds from one to six kilometres some forest elephants carry seeds as far as 57km. According to a study, the African forest elephants spread as many as 346 seeds per km from a variety of plants and trees every single day. The journey through an elephant’s guts proves useful for seeds—their hard shells are scarified readying them for germination. Once excreted as part of elephant dung, they are wrapped in a nutrient rich environment that enables their growth.
When the jungle is shrouded in darkness, winged night time gardeners begin their work. Nectar loving bats use echolocation and the sense of smell to spot certain species of large, strong scented flowers and in turn pollinate them. 500 species of plants in the tropics and deserts, including species of cocoa, durian, guava, mango, agave and banana are pollinated by them.
The baobab tree called Africa’s ‘tree of life’ depends solely on these flying mammals to be pollinated. Fruit bats are known to be particularly important in spreading seeds in logged or damaged forests where other animals might not venture, thus helping restore disturbed forests. Even bat excrement or guano, that seeds are covered in is rich in nitrogen, phosphate and potassium – the three components of any good fertiliser.
Primates—apes, monkeys and prosimians such as lemurs and lorises don’t just love their fruits, but plant them liberally as they forage. Some species such as orangutans are known to make tools to carve out their fruits. Their high density in many forests, usage of different kinds of canopy and relatively bigger sizes adds to their importance as seed dispersers.
They consume diets rich in a variety of fruits and defecate the seeds. In fact, primates are responsible for 40 percent of the fruit biomass in tropical forests. In Congo, bonobos disperse seeds from 65 percent of the tree species and 11.6 million seeds are dispersed during the lifetime of each ape. In Madagascar’s forests species of lemurs are known to be the primary animals who ‘plant’ seeds by scattering them. While howler monkeys are important seed droppers in Central America.
They maybe tiny, but they play a large role in keeping the forest ecosystem diverse. If large mammals are experts in sowing fruit seeds, these assiduous workers particularly like to spread seeds of wildflowers. They are known to disperse over 3000 plants species in both tropical and temperate forests.
The special relationship they share with plants, dispersing seeds, is termed myrmecochory. Several species of plants will produce a fleshy outer surface on its seeds to attract ants, which in turn will transport the seeds to their nests, sowing some along the way. The important function ants provide is salvaging these seeds before they are ruined by predators such as rodents. When the ants eat the outer surface, the seeds germinate quicker and there’s better soil in ant nests to sprout in.
Among gardeners with wings no other birds compare to the reputation of hornbills. Over 50 species of these large birds with downturned beaks are among primary seed sowers in the tropical forests of Asia and Africa. With 75 to 100 percent of their diets made up of various kinds of fruits, these birds are known to disperse as many as 748 species of fruit trees.
They particularly love to peck on and disperse figs—which are important species several forest creatures rely on. The birds will regurgitate large seeds that they can’t swallow and some species are known to travel as far as 290km making them important long distance gardeners.