Why Do Native Plants Boost Biodiversity In Hawaii Landscapes

Hawaii is one of the most isolated island chains on Earth and one of the most biologically unique. Native plants in Hawaiian ecosystems evolved in isolation for millions of years, producing an exceptionally high rate of endemism and complex, interdependent relationships between flora, fauna, fungi, insects, and people. When native plants are used in landscapes — from urban yards to large restoration projects — they do more than look beautiful. They restore ecological function, support native wildlife, and increase resilience against threats such as invasive species, pests, and changing climate.

The ecological foundations: evolution, specialization, and isolation

Island isolation favors unique evolutionary pathways. Many Hawaiian plants evolved traits tuned to local pollinators, seed dispersers, soil microbes, and climatic microzones. Native plants are the product of:

• long evolutionary time, producing endemic species found nowhere else;
• coevolution with native animals, including nectarivorous birds and specialized insects;
• adaptation to a range of soil types and microclimates across elevation and rainfall gradients.

These evolutionary foundations mean native plants provide resources in forms and at times that nonnative species usually do not. Nectar, pollen, fruit phenology, leaf chemistry, and structural habitat match local animal needs. When landscapes replace invasive or nonnative species with native plants, those coevolved relationships begin to reestablish.

How native plants support greater biodiversity

Native plants increase biodiversity through several concrete mechanisms:

1. Food resource matching and the return of native consumers

Many Hawaiian pollinators and frugivores depend on native plant phenology and morphology. For example:

• Ohia lehua (Metrosideros polymorpha) produces copious nectar that fuels native honeycreepers such as the i’iwi (Drepanis coccinea) and apapane (Himatione sanguinea).
• Native shrubs and trees produce fruits timed to the needs of endemic birds and seed-dispersing insects.

When these native plants are present in landscapes, native bird and insect populations find the specific food types they evolved to use, raising survival and breeding success.

2. Habitat structure and microclimate provision

Native species often create complex vertical structure and specific microhabitats — groundcover, understory, midstory, and canopy — that support a diverse set of organisms. For example, mature koa (Acacia koa) and ohia stands support epiphytic plants, native arthropods, and snail communities by moderating light levels, humidity, and soil temperature.

3. Soil health and microbial partnerships

Many native plants form specialized relationships with native mycorrhizal fungi and nitrogen-fixing bacteria. These relationships:

• increase nutrient cycling efficiency;
• improve soil structure and organic matter accumulation;
• favor native seedling establishment over invasive weeds.

These belowground networks are essential for sustaining native plant diversity and the animals that depend on it.

4. Resistance to invasive species and pests

Well-established native plant communities are often more resistant to invasion than monocultures of nonnatives. Native plant assemblages can:

• occupy ecological niches that invasive species would otherwise exploit;
• maintain active nutrient cycles and dense native groundcover that prevent invasive seedling establishment;
• support native predators and parasitoids that control exotic herbivores.

In short, native plants help restore the checks and balances needed for a diverse, functioning ecosystem.

Examples of native plant roles in Hawaiian landscapes

Native plants serve distinct roles across habitat types. Here are practical examples:

Coastal strand and dune systems

• Scaevola and naupaka species stabilize sand and provide nectar for insects and birds.
• Native grasses and sedges trap sand and reduce erosion, preserving habitat for nesting seabirds.

Lowland dry and mesic forests

• Koa and mamane (Sophora chrysophylla) fix nitrogen and create island-specific forest structure supporting endemic insects and birds.
• Native shrubs provide nectar and berries that sustain resident and migrating species.

Montane wet forests and bogs

• Ohia lehua dominates many montane wet forests and supports endemic pollinators and native understory plants.
• High-elevation bog plants like ohelo (Vaccinium reticulatum) and specialized sedges maintain unique hydrology and host endemic invertebrates.

Practical landscaping steps to maximize biodiversity

Landscapers, homeowners, and restoration practitioners can take specific actions to ensure native plantings boost biodiversity rather than simply adding plants that are “native” in name only.

• Start with site assessment: know your elevation, rainfall, soil type, and exposure. Choose species adapted to those local conditions.
• Prioritize locally adapted genotypes: use plants propagated from local seed sources or regional nurseries to preserve genetic adaptation and coevolutionary relationships.
• Plant communities, not isolated specimens: group canopy, midstory, and groundcover species together so wildlife finds food, shelter, and nesting material in one area.
• Provide a continuous sequence of flowering and fruiting: select species with staggered bloom and fruit times so birds and pollinators have consistent resources through the year.
• Control invasive species before planting: remove aggressive invaders such as strawberry guava (Psidium cattleianum), miconia (Miconia calvescens), and fountain grass (Pennisetum setaceum) to reduce competition and fire risk.
• Use mulch and organic amendments to jump-start soil microbial communities and protect seedlings from erosion.
• Protect plantings from feral ungulates and rodents: install fenced exclosures or tree guards where pigs, goats, or deer are present, and manage rats and mongooses that can eat seeds and nestlings.
• Monitor and adapt: track bird and insect use, seedling survival, and invasion levels, and adjust species composition or maintenance accordingly.

Plant selection guidelines by landscape goal

Choose species based on the explicit biodiversity outcome you want to achieve:

• For pollinator habitat: prioritize nectar-rich natives such as ohia lehua (Metrosideros polymorpha), mamane (Sophora chrysophylla), and native lobeliads and hibiscus species.
• For bird food and nesting: select fruiting trees and dense shrubs like kukui (Aleurites moluccanus, note: an early Polynesian introduction with cultural importance), naupaka, and native berry-producing shrubs.
• For soil stabilization and stream protection: use native sedges, Carex spp., and deep-rooted natives that reduce erosion and filter runoff.
• For dryland restoration: choose drought-tolerant native shrubs and trees such as aalii (Dodonaea viscosa) and certain Pritchardia palms.

Cultural and social biodiversity benefits

Native plantings do more than support wildlife. They reconnect people with cultural practices and knowledge, providing native materials for traditional crafts, medicinal uses, and ceremonial functions. Restoring native plant communities supports cultural biodiversity by sustaining local language, customs, and intergenerational knowledge transfer.

Common challenges and how to overcome them

Native landscaping in Hawaii faces practical obstacles. Being realistic about these and applying targeted strategies increases long-term success.

Invasive plants and momentum

Invasives spread quickly and outcompete natives. Overcome this by:

• intensive initial removal of invasives before planting native communities;
• using repeated follow-up weeding and monitoring for at least 3-5 years after planting;
• applying native cover crops and dense plantings to outshade invasive seedlings.

Feral animals and seed predation

Feral pigs and rodents can decimate young native plantings. Responses:

• install robust fencing around restoration sites and tree tubes or mesh around saplings;
• trap or otherwise manage invasive mammals in consultation with local authorities and cultural practitioners.

Limited nursery availability of local genotypes

Not all native species are available in nurseries as local genotypes. Solutions:

• work with native plant nurseries that specialize in regional collections;
• participate in community seed-collection networks and propagation workshops;
• advocate for increased production of native seedlings by public and private nurseries.

Measuring success: metrics and indicators

To verify that native plantings are boosting biodiversity, track measurable indicators:

• species richness: count the number of native bird, insect, and plant species using the site annually.
• population trends: monitor key indicator species such as native honeycreepers or endangered invertebrates.
• vegetation structure: track canopy cover, native groundcover percent, and presence of multiple vertical layers.
• invasive species cover: measure reduction in invasive plant percent cover over time.

These metrics guide adaptive management and help secure funding or community support.

Final takeaways: practical, evidence-based steps

• Use native species adapted to your specific elevation, rainfall, and soil conditions; local genotypes when possible.
• Plant in communities with staggered flowering and fruiting to provide year-round resources for native wildlife.
• Remove and control invasive plants and animals before and after planting to give natives a competitive edge.
• Build soil and microbial health through organic practices and by favoring species with beneficial fungal and bacterial partnerships.
• Protect plantings from feral ungulates and rodents with fencing and active management.
• Monitor biodiversity outcomes and adapt your approach based on measurable indicators.

Native plants are foundational to restoring Hawaii’s unique biodiversity. They rebuild lost ecological relationships, support endemic wildlife, stabilize soils and watersheds, and sustain cultural practices. Thoughtful native plant selection and management can turn private yards and public landscapes into functioning ecosystems that enhance biodiversity across the islands.