Fill in the Blanks Ecological Succession (D)Online version Fill in the blank to this reading about ecological succession. by Anne Smith 1 succession increase small primary destroyed fire pioneer years producing soil ecosystem Ecological is a series of steps to establish or re - establish an after it is destroyed . The first species to live in a new ecosystem are called species , like lichen , bacteria or small grasses and weeds . There are two types of succession : and secondary . In both types , the number of organisms start and over time until the ecosystem reaches is carrying capacity - where no new species can colonize . Primary succession is when a NEW ecosystem develops , it is new because ( dirt ) needs to be made BEFORE anything else can happen . Secondary succession occurs after an ecosystem is , but leaves the soil - like in the case of a . Secondary succession is much quicker than primary succession . since primary succession requires the of soil , which can take decades or even hundreds of .