The reason is two fold, the first is the active volcano of Kilauea implies there is a lot of heat under the big island of Hawaii, and that heat causes the island to be buoyed up. However, the other islands do not have active volcanos, are colder, and have subsided, the 2nd is, because the volcanoes on the older islands are dormant, those islands are and are no longer growing and are steadily eroding away.
True, organisms take in nitrogen and carry out life processes.
Orchids are now grown through vegetative propagation, rather than seeds, courtesy of developments in cloning. This allows many orchid plants to be grown from a portion of a single orchid plant. This allows even the rare orchid o to be grown in mass. There is also little variation when cloning s done as compared to growing with seeds.