DENDROLOGY

Detailed explanation-1: -The term pioneer is used to describe the species that first colonize new habitats created by disturbance. Although the term is usually applied to plants, microbial and invertebrate pioneer species are also sometimes recognized.

Detailed explanation-2: -In this case, the pioneer species are plants such as grasses, birch trees, and fireweed. Organic matter from the pioneer species improves the soil.

Detailed explanation-3: -Explanation: Pioneer species are the first species to colonize an environment, and thus would be found in the early stages of succession.

Detailed explanation-4: -Pioneer species are hardy species that are the first to colonize barren environments or previously biodiverse steady-state ecosystems that have been disrupted, such as by wildfire.