Have you ever wondered how seeds are spread? How there can be kilometres between one mulberry tree and another?
Seed dispersal makes the distribution of individual plant species possible, but it also creates a chain reaction towards biodiversity.
It starts with weeds
Weeds are notorious for growing quickly and in the most “inconvenient” spaces. As pesky as they seem, weeds and their growth, flowering and seeding habits serve a purpose for their own preservation and our soil’s.
Weeds are crucial to the regeneration of land as their quick growth ensures that the soil is never bare for long. Their specifically designed roots help hold soil structure together to prevent it from eroding while also unlocking nutrients for other plants.
This encourages weeds to seed and spread often, and since they shoot up and flower throughout multiple seasons, they become trusted homes and food sources for insects. What happens with an abundance of bugs? Nature begins to regulate itself, and birds and other seed-dispersers begin to recognize the area as a hot spot for food.
Photo by Jasmin Schreiber on Unsplash
Then come the animals
Many “weeds” or wild plants, bushes and trees are also known to fruit. Both fruit and insects are highly prized food items for birds, whereas nuts, seeds and fruit are known to attract squirrels and other rodents.
Animals like birds and squirrels disperse seeds by excreting (pooping) or burying them. Think of a squirrel burying a nut; he may think he’s burying it for winter storage, but will often forget all of his “hiding spots” which results in a planted seed.
However, there are also weeds and plants with hook-like or sticky structures that will attach themselves to animals’ fur (or people’s legs) in order to migrate further from the parent plant. Humans also play a role as dispersers by moving fruit to new places and discarding inedible portions containing the seeds. Ideally, in all situations, the seeds will be moved as far away as possible. This is the goal of plants because if they grow too closely together, they’ll have to compete for the same nutrients in the soil, water and sunlight.
Dispersing fruits, nuts and other larger seeds begins the process of creating habitat for even larger creatures to make homes in and encourages the beginning of an ecosystem.
Photo by Benoit Gauzere on Unsplash
Elements play a part in dispersing seeds too
Of course, we can’t deny the role that the elements bring to the table. When natural areas are left alone, seeds have an easier time spreading and establishing roots. Seeds can be carried by air, like our “wish-making” friend, the dandelion, whose seeds we (or the wind) blow around. This scattering helps the plant to reproduce, and depending on how light the seed is, it can travel quite the distance.
Gravity also plays its part in dispersal. Seeds fall from a tree in a process called abscission, and is most common for fruits like apples and berries, or nuts like walnuts and acorns. The process includes an increase in heaviness in the fruit combined with chemical signals that encourages the plant to drop the fruit and for the seeds inside to be most viable for germination.
Bodies of water are impressive dispersers for waterborne seeds, which are buoyant by being enclosed in a corky or air-containing pod. These light seeds can be carried through ponds, swamps, or even by ocean currents, to land on shores half a world away. Water is particularly effective because these seeds can move long distances and germinate in isolated places like islands.
Photo by Олександр К on Unsplash
A chain reaction to fertile land
An abundance of plants and animals through seed dispersal leads to an entire ecosystem filled with decay, decomposition, fungus and bacteria, which helps wild areas regenerate. Land is made fertile through all of the steps combined, which is why we see more success in trees grown in forests rather than in bare yards or alongside sidewalks.
We can encourage a reawakening of wild areas by seeding native plants, trees and shrubs around our yards and neighbourhoods. With one seed (and with a little time and patience), we can help create a chain reaction towards complete biodiversity.