What counts as an invasive tree species in California?

Invasive trees are non-native trees that spread aggressively and cause ecological, economic, or safety impacts. In California, lists and inventories help identify which species are actively damaging natural areas and which are high-risk watch species.

Where can I verify whether a tree is considered invasive?

Start with California-focused inventories and plant profiles (such as Cal-IPC), then cross-check distribution in mapping tools and local extension or land management guidance.

Should I remove an invasive tree myself?

Small seedlings may be manageable, but many invasive trees resprout aggressively when cut. For larger trees, consult local guidance and consider a professional—especially near structures, waterways, or utility lines.

How do I report an invasive tree sighting in California?

Use regional reporting and mapping tools when available and include photos plus a precise location. You can also contact local invasive species programs, land managers, or extension offices.

What is the biggest mistake when controlling invasive trees?

Removing the top growth without stopping resprouting or seed spread. Successful control usually combines correct timing, follow-up monitoring, and safe disposal to prevent re-establishment.

Invasive Trees & Plants That Grow in Hawaiʻi (Island-by-Island Guide)

Identify • Report • Control

Invasive Trees & Plants That Grow in Hawaiʻi: Local Resources Linked to the Weed Trees Hub

This page is a California companion to our national guide: Invasive Tree Species (Weed Trees). Use it to confirm what’s considered invasive in California, verify identification, and find the most useful mapping and reporting tools.

Fast path: get photos → confirm ID → check inventories/maps → report → choose control + follow-up. The goal is to prevent spread (seeds and vegetative fragments) and avoid “cut-and-sprout” failures.

Jump to: quick links • common invasive trees • verify & report • control playbook • FAQs

Hawaiʻi Quick Links (Start Here)

Use these official resources to identify invaders, report sightings, and protect native forests across the islands.

National hub

Invasive Tree Species (Weed Trees) — definitions, red flags, and prevention.

Report statewide

Report online (643pest.org) or call 643-PEST (808-643-7378).

Island response teams

BIISC (Hawaiʻi Island) · MISC (Maui Nui) · OISC (Oʻahu)

Why Hawaiʻi is different: native forests evolved in isolation. Invasive trees and invasive plants can form dense, single-species stands that block regeneration of indigenous trees, reduce watershed function, and transform habitat.

Island-by-Island Examples (2 per island)

Below are examples of invasive trees and invasive plants commonly associated with forest conversion and ecosystem disruption in Hawaiʻi. The goal is fast recognition and smart action — especially where invaders threaten native canopy species like ʻŌhiʻa lehua and koa.

Hawaiʻi Island (Big Island)

Miconia (Miconia calvescens)

Dense shade can suppress native understory and regeneration in wet forests; high erosion risk on steep terrain.

Strawberry guava / waiawī (Psidium cattleianum)

Forms thick stands that replace diverse native forest structure, changing habitat and watershed behavior.

Wet forest invaders Watershed impacts Report: BIISC

Maui (Maui Nui)

Albizia (Falcataria moluccana)

Rapid canopy takeover in disturbed areas; can outcompete native trees and increase storm-damage hazards.

Miconia (Miconia calvescens)

Spreads in wet zones; shades native forest and complicates restoration by blocking light and recruitment.

Disturbance colonizer Wet forest conversion Report: MISC

Oʻahu

Java plum (Syzygium cumini)

Invades valley and lowland zones; can suppress native regeneration and alter forest composition.

Albizia (Falcataria moluccana)

Fast-growing, shallow-rooted; frequently dominates edges and disturbed corridors, displacing native trees.

Valleys & edges High wind-fall risk Report: OISC

Kauaʻi

African tulip tree (Spathodea campanulata)

Can dominate moist areas and edges, shading native understory and slowing indigenous tree recruitment.

Strawberry guava / waiawī (Psidium cattleianum)

Turns mixed native forest into single-species stands, reducing habitat diversity and forest resilience.

Forest conversion Understory suppression Report: 643-PEST

Lānaʻi

Christmas berry (Schinus terebinthifolia)

Invades dry to mesic zones; forms dense thickets that can crowd out native shrubs and young trees.

Ironwood (Casuarina spp.)

Common along coasts; can displace native coastal plants and alter sand movement and coastal habitat.

Coastal displacement Thicket formation Report: 643-PEST

Molokaʻi

Albizia (Falcataria moluccana)

Edge-dominant canopy invader; increases hazardous blowdown and can suppress native forest recovery.

Strawberry guava / waiawī (Psidium cattleianum)

Monotypic stands reduce regeneration opportunities for indigenous trees and simplify habitat structure.

Watershed priority Forest simplification Report: 643-PEST

How Invasive Trees & Plants Impact Indigenous Hawaiian Forests

Block native regeneration: dense shade and leaf litter can prevent seedlings of indigenous species from establishing.
Convert diverse forest into single-species stands: reduces habitat complexity needed by native birds and invertebrates.
Change water behavior: forest conversion can reduce watershed function and increase erosion on steep slopes.
Disrupt restoration: many invaders resprout after cutting and require follow-up, coordinated control.

Best practice: prioritize early detection, treat small/new infestations quickly, and coordinate with island response teams.

Native Replacement Guides (What to plant instead)

Replanting with native and Polynesian-introduced canoe plants helps restore habitat, stabilize soils, and support long-term forest resilience. The right choice depends on elevation, rainfall, and exposure. Use this as a starting point — then confirm with local nurseries and guidance.

Instead of Albizia

Consider: koa (Acacia koa), koaiʻa (Acacia koaia), milo (Thespesia populnea), kou (Cordia subcordata) in appropriate zones.

Instead of Strawberry guava

Consider: native understory + canopy mixes suited to your site: ʻōhiʻa, lama (Diospyros sandwicensis), naio (Myoporum sandwicense), ʻōlapa (Cheirodendron trigynum) where appropriate.

Instead of Miconia

Consider: native wet-forest restoration mixes guided by watershed partners; favor diverse plantings (not single-species) to rebuild structure over time.

Helpful reference: Hawaiʻi Forestry & Agroforestry Trees (CTAHR).

Pacific Islands Cluster (Internal Link Hub)

Invasive species pressure is a shared challenge across Pacific islands. Use this cluster to connect Hawaiʻi with nearby island-region hubs.

Invasive Trees & Plants That Grow in Hawaiʻi

Softwoods

Hardwoods

Calculators

Resources

Programs

Invasive Trees & Plants That Grow in Hawaiʻi: Local Resources Linked to the Weed Trees Hub

Hawaiʻi Quick Links (Start Here)

National hub

Report statewide

Island response teams

Island-by-Island Examples (2 per island)

Hawaiʻi Island (Big Island)

Maui (Maui Nui)

Oʻahu

Kauaʻi

Lānaʻi

Molokaʻi

How Invasive Trees & Plants Impact Indigenous Hawaiian Forests

Native Replacement Guides (What to plant instead)

Instead of Albizia

Instead of Strawberry guava

Instead of Miconia

Pacific Islands Cluster (Internal Link Hub)

Guam

American Samoa

CNMI

Tree Plantation

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Head Office

Field Office