Question
using simple wording can you please explain what bio diversity is and how it can be applied to gardening

Answer
BIODIVERSITY is the range of living things in an environment, from the smallest microscopic being to the largest mammal.  The richest biodiversity is found in tropical climates; there's very little biodiversity near the Poles.  Ecologists consider Biodiversity a sign of a healthy natural ecosystem.

I'm not sure what you're looking for, but I am inclined to think that gardening would negatively impact the biodiversity of the land around a home.  Plants are selected for personal taste, not for their contributions to the ecosystem outside your window.  You like the fragrance.  Or the color of the leaves.  Or the long blooming season.

And yet, these plants are disturbing native plants you don't even know you had.  Some develop into Noxious Weeds, escape, and compete with native plants.  The highly controlled environment of the garden simply cannot support biodiversity.  The visiting native species that appears out of the blue is quickly branded a Weed and removed.

Chemicals used in the garden also interfere with biodiversity.  The Salts in commercial Fertilizers are toxic to many species of worms, Nematodes, etc.  Ditto, pesticides.  Destroying these fauna and flora is bad for biodiversity.  But gardeners are a progressive bunch as a rule.  Don't be surprised if you start reading accounts of gardeners who let their landscape grow all on its own, in the interests of biodiversity and all it embraces.

Make sense?

THE LONG ISLAND GARDENER