The Biomass is big in the topical rainforest is big because ...
of the monkeys
Because there is a lot of solar energy and temperatures are high every month so plants can take up nutrients through out the year .
The constant heat allows bacteria in the leaf litter to reproduce very quickly so decomposition is rapid and nutrients are transferred back to the soil.
Tall trees reach sunlight to photosynthesise
Temperatures in the desert can reach 40.c in the day