Table 1. Distinctive structural and demographic features of Hawaiian forests.

Environmental Conditions

Large variation in elevation, rainfall, temperature and soils among forests that are geographically close 1–2

High light levels in intact wet, mesic, and dry forest (1.9–40% diffuse light transmission) 3–9

Species Composition and Diversity Patterns

A global biodiversity hotspot due to high endemism and number of endangered species 10–11

Same species distributed in many habitats differing in environmental conditions, demonstrating exceptional phenotypic plasticity 10–14

Tree ferns common and often the understory dominant in wet forests at all elevations, whereas outside of Hawai‘i they tend to be more restricted 10

Monodominance by a few canopy species 15

Autecology of Plant Species

Metrosideros polymorpha dominant in wet forests throughout succession (as pioneer and late successional species) 15–17

Extremely slow growth of primary pioneer species, M. polymorpha (1–2 mm/year diameter) 18–20

Nurse logs serve as a substrate for seedling regeneration 21

Dieback and regeneration of canopy dominant M. polymorpha in cohorts contribute strongly to gap dynamics 16, 22

Trophic Interactions

Evolution without land mammals 23, 24

Documented extinctions of plants, pollinators and dispersers may influence present day evenness and rarity measures 23

Animal dispersal of seeds conducted entirely by birds before human contact 24, 25

Apparently low rates of insect herbivory 26 and seed predation 27

Presence of invasive weeds, ungulates, and birds may alter present-day plant-animal interactions 25–26, 28

Superscripts refer to references listed in Table S5 in File S2.