Total species diversity in a landscape (γ)
is determined by two different things, the mean species diversity in
sites or habitats at a more local scale (α) and the differentiation
among those habitats (β). The relationship between them is γ = α * β. If you could increase alpha and beta diversity without decreasing gamma-scale diversity, then you would be creating more biodiversity. This is desirable! More biodiversity means that a particular ecosystem or environment is more stable, more productive and more resistant to environmental stress than other ecosystems.