Mesophytic Climax community in succession?

Question

My textbook says that in all cases of ecological succession (xerarch, hydrarch, etc.), the ultimate climax community, assuming constancy of environment, is a mesic community. Xeric or hydric pioneers are ultimately succeeded by mesic climax communities. Why is this so? In an environment under consideration, if for example water stress prevails (characteristic of xeric environments) shouldn't the final community be xeric and hence better adapted to the environment? Is my book wrong, or is there something I am missing in the understanding of the development of climax communities?

Moreover, I did find it written somewhere that mesic communities do depend on the climate of the place. But then doesn't the fact it is mesic contradict a few climatic conditions wherein ecological succession might occur?

Reference:-
Ecological Succession
Climax Community

Answer 1

The concept of a "climax community" has not been accepted as reality for more than 40-50 years. Frederic Clements was an early botanist examining succession in the first 20 years of the 20th century. It was Clements who developed the concept of the climax: he posited that the habitat and the populations acted upon one another in a reciprocal way until finally a stable state (the climax) was reached.

However, the work of Gleason (e.g, 1926), Tansley, Watt (1957), Whittaker (e.g., 1972), Davis (1969), etc. have changed the field's understanding of succession and its acceptance of the existence of a stable "climax". Whittaker was first to propose the use of the term "stable state," as it carried less assumptions about the community' inability to be replaced.

It's now clear from work of countless studies and authors (along with my own research), that disturbances play a significant role in plant dynamics and that previously accepted 'stable states' are perhaps only remnants of historical characteristics of the system (see below). As a result, some accepted stable-state communities no longer appear to be the norm in some areas (likely due to both present and past disturbances and fluxes in the system). See Abram's papers for a discussion on hypotheses of this phenomenon in the Eastern deciduous forest of the U.S.

Regardless, even in a system without disturbance (which none exist), the stable-state community would be fully dependent on climate, substrate, community assembly limitations and geographic/environmental/biological filters.