The biodiversity increases when one moves from the pioneer to the climax stage. What could be the explanation ?

During ecological succession, it reaches to climax of primary stage, biodiversity increases or gets changed.

The effects of ecological succession is as follows:

$(a)$ It brings changes in plants which affects food and various types of habitates of animals.

$(b)$ As succession proceeds further changes came in type and number of trees, animals and decomposers.

$(c)$ During primary or secondary succession, at any time disturbance created either naturally or manmade like fire and deforestration which convert into previous stage inplace of definitely stage of succession stage.

Moreover it can create new disturbance new stage which activate some species and removes or make them dull the some producers consumers and decomposers species.

$(d)$ As time passes it leads towards large trees. At its end jungle ecosystem is obtained sequentially reached permanent climax community.

$(e)$ If environment is not changed then group reached at climax community.

$(f)$ With passing time, desert habitat are changed into revenue mesophytic.