Each component of biodiversity performs various functions or roles and occupies a particular niche.

Biodiversity

We seem to hear a great deal about biodiversity these days - it is one of the ‘buzz’ words since the last half of the 1990’s.

Biodiversity means the total of all life on earth. When natural ecosystems, with the great diversity of species which they have, are invaded by weeds such as bridal creeper or feral animals like the rabbit and fox which become strongly dominant, biodiversity suffers. But does the ecosystem suffer? Could it be just as important to have a tonne of biomass (living material) of one type, as it is to have a tonne of biomass made up of many living things.

Each component of biodiversity performs various functions or roles and occupies a particular niche, a place within the food chain where other species can become dependent upon another, a third species becomes dependent on the second, and so on. As the complexity of an environment builds, the number of symbiotic (mutually dependent) relationships increase. This complexity of life performs a number of functions for humans. The formation and fertility of soils depends on the diversity of life in the soil. The fertility of the soil gives rise to the plants that produce oxygen from carbon dioxide and clean the air. The entire complexity produces all the services on which we depend, including the essential mix of atmospheric gasses, our food, clean water, chemicals and drugs, as well as the unique landscape in which we live. So our very existence depends on biodiversity.

We should preserve biodiversity for the following reasons:

• We are not yet smart enough to know with great certainty which parts of the diversity of life are absolutely essential and which can be replaced.
• Over simplification of ecosystems by human activity often causes problems that are costly to solve (erosion, loss of water quality, increase in infectious diseases. Weediness etc).
• We do not know what useful components we may find in any part of the system in the future (drugs, chemicals etc).

Diversity is generally thought to comprise three components;

1. Genetic diversity
2. Species diversity
3. Ecosystem diversity.

Genetic diversity is the sum of genetic information contained in the genes of individual plants, animals and microorganisms. Genetic diversity produces inherited variation that makes each organism unique. It is important because it allows populations to adapt to changed conditions.

Species diversity refers to a group of individuals that can interbreed with one another, to produce offspring that can also reproduce. Species diversity is easy to see and therefore most of us are familiar with the idea of preserving species to enhance biodiversity.

Ecosystem diversity relates to the variety of habitats, biological communities and ecological processes. Each separate ecosystem has the ability to support a range of species, so as we move between different environments, such as lakes, rivers, swamps, deserts, woodlands, forests, heathlands, grasslands, seashores, estuaries, coral reefs, open oceans and so on, so the communities of species change. If we wish to preserve the associated species, we have to preserve examples of each different ecosystem.

When we interfere in an ecosystem, we change one or all of these components in a way that invariably reduces one aspect of biodiversity.

It is not the fault of the bridal creeper, rabbit, fox or cat that diversity will be reduced by their presence, but it is a consequence of their introduction and it does make a difference. Until we become a lot wiser about which components perform what roles and how they may be replaced or enhanced without long-term harm, we should practice humility and allow natural systems some room to perform their life-sustaining biological functions.

An Ace up your sleeve

I have been thinking about biodiversity recently like a pack of cards. The different suites represent ecosystems, the card values (Ace through to Kings) represent the species and the individual cards (five of clubs, spades, hearts or diamonds) represent genetic diversity.

I could toss out the twos, threes and fours, and still play short-deck Five Hundred or Poker. But then the pack would not work if I wanted to play Five Hundred with four players. A short deck is OK for two players, but if I want to involve more players, I need the full pack.

I could rip the five of clubs in half, because I have a joker that can ‘become’ or serve as (fulfil the same function as) the five of clubs. I could rip up the five of diamonds, because I have another joker. I could do this a couple more times because my pack has a blank card and another with advertising for the manufacturer. But if I let this habit run rife I may suddenly find that I have no jokers left. Then I will not even be able to play patience.

Even with a degraded pack, I can play some games. I could randomly toss out a dozen cards and still play snap - but snap is a much less satisfying game than whist or bridge.

In my example, I want to keep the full pack, to allow a maximum diversity of future uses (i.e. I can play any game I wish).