Tidal fluctuations drive some major processes in mangrove forests and shape the canopy. Few among others are as follows:

a. Inundation of a coastal landscape with saltwater during high tides helps exclude most other vascular plants from the area and helps mangroves to grow over the area. Thus it shapes the canopy, its distribution and diversity in turn.

b. Tidal waters bring in sediment and nutrients from landward side and nourish the forest.

c. Where the rate of evaporation is high, tidal water flushes forest sediments and bring down the salinity.

d. Tidal water carries mangrove diaspores with it and influence the species distribution, directly.

I will try to complement the thorough response of Dr. Dola Bhattarcharjee, since the original question referred to the tidal amplitude and its influence on the forest canopy and the atmosphere greenhouse flux footprint. First, a generous amplitude combined with the topography will create an appropriate strip of land for the growth of mangroves and the exclusion of competition from other vascular plants. The lower limit of the mangroves (i.e. seaward) will be given by the ability of individual species to tolerate prolonged flooding.

Referring to sediment and nutrients, a large amplitude could distribute them in a strong gradient and, in turn, determine the zonation of species. Conversely, washing will be different if the tidal range is large or small, which in turn is valid for sediment, salinity and propagules.

Dr. Dola Bhattarcharjee and and Dr.Jaime Polania Vorenberg gave well and detailed explanation for the above question. I would like give few points regarding that questin. 

TIdes play vital role for the growth and formation of mangroves and its canopy, and these are reposible for the formation of zonation in the mangrove ecosystem especially from water front to land ward zone. Water front region was dominated by the true mangroves which shows the vivipary, slit roots and with other adaptations, from water front to land ward there is gradual reduction of the canopy and height of the forest also.This is due impact of the tides and its action and  further near the land ward region is dominated by the halophytes.  In between halophytes and terrestrial plants barren zone is present , if tides reach this region growth of the halophytes will be observed