We have spoken a lot about biodiversity on this page. But how does it really affect us? If we are the dominant creatures in nature, then why can't we survive alone? Why should we share earth's resources with anyone else? To understand the importance of biodiversity, let's break it down a bit.
The building blocks of life for every living organism are some matters like Oxygen, Nitrogen, Carbon, Sulphur, Phosphorus, Water, Calcium etc. In order to survive, we have to consume each one of these matters in prescribed (by nature) quantities. These are the nutrients that keep us alive. We breathe oxygen, drink water, eat carbohydrates, etc. Also matter is indestructible (Law of Conservation of Matter), it only changes form (or builds compounds). Every bit of matter that we consume throughout our lives, we give it back to nature at some point of time, through bodily functions like defecation, urination etc. and finally through decomposition by bacteria after death.
Few concepts critical in this context are
1. Matter is consumed in prescribed amount,
2. Matter changes its form and
3. Matter recycles through the ecosystem
Every living being has capacity to process these matters in only specific forms. In other forms, the same matter can be unusable at the least and toxic or even lethal at the most. When matter is passed on from one source to another, many times it changes its form (to create some compounds, for example nitrates, phosphates etc). So the matter is then broken down by some other organism that is capable of doing so in its current form before another organism can absorb it. This recycling can take any time between few hours to thousands of years and can change its form many times before the cycle completes.
The ability of any organism to process any matter in certain form depends on many factors like temperature, water, presence of another organism, etc. These conditions can have millions of different combinations. This is where the importance of millions of species comes in. Only in the perfectly balanced natural conditions, some combinations of species are able to create the matter required for living beings. Any imbalance will lead to toxic environment.
When we change natural conditions, like global climate, rainfall, number of species, forest cover, artificially changing the composition of these matters in the ecosystem, then we destroy this delicate balance and leave some of the stages of this recycle at risk.