State 1
Reference State

The Reference State consists of one community phase. Under a regime of natural disturbances, this community has probably been stable through post-glacial time frames and from a broad-scale spatial perspective. Rainfall and temperature vary based on elevation, while substrate varies by lava flow type (aa versus pahoehoe) and age. This produces a matrix of natural variability that changes over a scale of decades and centuries as soils and vegetation communities develop. Overlaid on this matrix are more localized variations caused by wind throw, tree death, and propagule availability. New lava flows bring about a return to primary succession that proceeds at different rates due to lava type and climate. Much of this ecological site has been cleared for livestock grazing, either mechanically or simply by allowing livestock to graze and browse the native understory. This represents a transition to State 2 Naturalized Grassland. Clearing the forest and then planting introduced timber tree species results in a transition to either State 3 Tree Plantation with Exotic Understory or State 6 Tree Plantation with Native Understory, depending on local availability of seeds for native or invasive introduced species. Gradual invasion by introduced species into existing forest results in State 4 Native Forest with Invaded Understory.

Community 1.1
`Ohi`a lehua - koa/hapu`u/kanawao

Figure 6. Reference community phase. 4/28/06 D Clausnitzer MU113

Figure 7. Nestegis-dominated variant. 11/1/05 D Clausnitzer MU112

Figure 8. Forest on younger lava flow. 1/17/06 D Clausnitzer

Figure 9. Reference community. 5/5/06 D Clausnitzer MU201

This community phase is a forest consisting of four canopy strata: an open or closed upper canopy of ohia lehua or ohia lehua and koa up to about 100 feet (30 meters) tall, a secondary canopy of diverse tree species 30 to 60 feet (9 to 18 meters) tall, a dense tree fern canopy 10 to 30 feet (3 to 9 meters) tall, and a diverse understory of shrubs, forbs, sedges, and ferns. Vines, particularly ieie, are common both on the ground and on trees. These forests have standing live timber of 900 to 8000 cubic feet per acre, with a representative value of about 5500 cubic feet per acre. Variability in both the overstory and understory occurs throughout this ecological site. This variability represents occurrences of a spectrum of differences in vegetation and soils that are primarily due to different lava flow ages. The different vegetation and soils apparently are succeeding to a common state. The rate of this succession is determined by local temperature and rainfall, and it can be set back to primary succession by unpredictable fresh lava flows.

Forest overstory. The uppermost forest canopy consists of ohia lehua or a combination of ohia lehua and koa. Total overstory tree canopy cover ranges from about 10% to 80%. Neither overstory species grows well in shade. Primary succession in Hawaii typically results in an initial forest overstory of ohia lehua consisting of roughly even-aged cohorts. Over time, a number of factors (discussed below) influence the overstory composition.

Ohia lehua dominates the forest canopy on younger lava flows, which also tend to be organic (highly decomposed plant material) soils rather than mineral (volcanic ash) soils. Older lava flows tend to be mineral, volcanic ash soils; these soils have a greater likelihood of koa occurrence. Koa is able to grow on both organic and mineral soils. Landscape surface age, and hence stage of succession, is more important to koa occurrence than is soil type (organic versus mineral/volcanic ash).

Koa is an opportunistic species that often occurs along roadsides or near old sawmills in areas where it does not occur in the forest but where logging operations have distributed koa seeds. Koa also can occur on soils on which it is typically not found, such as young organic soils, when those soils occur on narrow lava flows that have run through areas of older volcanic ash soils that support stands of koa.

In general, koa is more abundant at higher elevations (above 2800 feet) of this ecological site. The lowest natural koa occurrences are at about 2000 feet elevation. It is possible that populations of koa were more widespread at lower elevations in Kona in the past (personal communication, Rick Warshauer, 2006).

Forest understory. Understory composition appears to be controlled by the cover of the secondary canopy of medium-stature tree species and, in particular, by the cover of tree ferns, which is usually in the range of 60% to 90%. Koa and ohia do not reproduce successfully in the typically shady understory of intact forest. Tree ferns, medium-stature trees such as olapa, kopiko, kolea lau nui, kawau, and olomea, and shrubs such as kanawao and clermontia reproduce well in the understory. The ground layer of small ferns is typically very dense.

The most common secondary canopy tree species are olapa or olapalapa (Cheirodendron trigynum), kolea lau nui (Myrsine lessertiana), and kopiko (Psychotria spp.). The palm native to this ecological site, loulu (Pritchardia lanigera), is rare but may have been more abundant in the past.

The mid-canopy is dominated by olapa trees in the southern part of the ecological site; however, olapa is somewhat less abundant in the northern part.

The tertiary canopy contains small trees but is dominated by two species of hapuu or tree ferns, hapuu (Cibotium glaucum) and hapuu ii or hapuu li (Cibotium menziesii). Cibotium glaucum is the more abundant of the two species. Hapuu or Chamisso’s manfern (Cibotium chamissoi) is present but uncommon.

The lowest canopy stratum, which ranges in height from the ground to about 4.5 feet (1.5 meters), consists of seedlings and immature individuals of species in the taller strata, small shrub species, forbs, vines (some prostrate, some climbing, some both), sedges, and ferns and fern allies. Ieie vine (Freycenetia arborea) can be very abundant, both on the ground and climbing on trees.

Some of the youngest lava flows, especially on Mawae soil series, can have large ohia trees but an understory with much less tree fern cover, more abundant amau (Sadleria spp.) fern cover, and more abundant kolea lau lii (Myrsine sandwicensis) than is typical for this ecological site. This understory species composition reflects an earlier successional stage with less soil development.

State 2
Naturalized Grassland State

This state is comprised of three community phases that may or may not have an open canopy of remnant native trees (usually ohia lehua but sometimes koa). Koa may occur in or on the edges of grasslands on soils that do not usually contain koa as part of the original forest. These trees may be opportunistic individuals that have taken advantage of increased light and survived browsing long enough to reach maturity. Trees in these grasslands provide shade and protection from the elements to livestock. However, very little regeneration of trees occurs, so the trees will eventually die out. Community phase 2.1 usually consists of kikuyugrass (Pennisetum clandestinum) and/or pangolagrass (Digitaria eriantha) with an admixture of common vetch (Vicia sativa) or desmodium (Desmodium spp.). Continuous grazing that does not allow favored forage species time to recover from defoliation results in community phase 2.2, which is dominated by lower value forage species but contains enough remnant kikuyugrass to allow for a transition back to community phase 2.1 with prescribed grazing. Longer-term continuous grazing leads to community phase 2.3, which consists of low value grass species and increasing cover of weedy shrubs and vines. Improvement of this community phase requires weed control and restoration of desirable grasses in addition to prescribed grazing.

Community 2.1
Kikuyugrass/common vetch

Figure 10. Kikuygrass with native trees. 8/26/05 D Clausnitzer MU396

This community phase is maintained by grazing, which keeps preferred species from becoming too tall or dense, and adequate recovery periods, which ensure vigor and cover of preferred species. High production of preferred grass species and extensive cover allow for increased soil moisture retention, vegetative production, and overall soil quality. These factors are degraded by grazing practices that result in loss of preferred grass species leading to increase in less desirable grasses, weed invasion, and an increase in the extent of bare soil. The normal total annual production (all types and species of plants) of the grasslands in this community phase is about 4,000 lb/acre of forage. Above normal production is about 8,000 lb/acre; below normal production is about 2,000 lb/acre).

Forest overstory. Up to about 25% canopy cover of large, native ohia lehua trees may be present.

Forest understory. The dominant grass species is kikuyugrass, although pangolagrass also has been planted on some sites. Naturalized leguminous herbs, particularly common vetch and desmodium species, as well as a small admixture of cool-season grass species such as common velvetgrass (Holcus lanatus), orchardgrass (Dactylis glomerata), ryegrasses (Lolium spp.), and Kentucky bluegrass (Poa pratensis).

Community 2.2
Hilograss - common carpetgrass

Figure 12. Degraded kikuyugrass site. D Clausnitzer generic photo

This community phase is created and maintained by excessive, continuous grazing that favors growth of less desirable forage species. Cattle can be maintained on these forages, but animal growth and vigor will be reduced. Also, the number of weedy species is high, and their stature, seed production potential, and wide distribution can lead to rapid increase and a shift to community phase 2.3 unless management is improved.

Forest overstory. Up to about 25% canopy cover of large, native ohia lehua trees may be present.

Forest understory. Community phase 2.2 is dominated by grasses of lower forage value such as Hilograss (Paspalum conjugatum), common carpetgrass (Axonopus fissifolius), and sedges, plus forbs such as narrowleaf plantain (Plantago lanceolata). Desirable forage legumes have been reduced in abundance.

Community 2.3
Strawberry guava/hilograss - common carpetgrass/scaly swordfern

Figure 13. Weedy grassland. D Clausnitzer generic photo

This community phase is dominated by grass species that have little forage value. Spiny forbs and vines are common, as are a large number of forb and fern species with little or no forage value. Introduced shrubs and small trees are common, and seedlings and saplings of introduced tree species are present. The abundance of immature trees with potential mature heights of 20 to over 100 feet (6 to over 30 meters) presents a risk of losing the grassland to weedy forest.

Forest overstory. Up to about 25% canopy cover of large, native ohia lehua trees may be present; these provide shade to livestock.

Large specimens of invasive introduced tree species such as autograph tree or Scotch attorney (Clusia rosea), strawberry guava (Psidium cattleianum), octopus tree (Schefflera actinophylla), christmasberry or Brazilian peppertree (Schinus terebinthifolius), and African tuliptree (Spathodea campanulata) may be present.

Forest understory. Hilograss (Paspalum conjugatum), common carpetgrass (Axonopus fissifolius), broomsedge bluestem (Andropogon virginicum), and beardgrass or Colombian bluestem (Schizachyrium condensatum) are the most abundant grasses. West Indian raspberry(Rubus rosifolius)and cat's claw or shoofly (Caesalpinia decapetala) form small thickets. Shrubs such as cure for all or sourbush (Pluchea carolinensis), along with small trees such as strawberry guava (Psidium cattleianum) and Christmasberry or Brazilian peppertree (Schinus terebinthifolius) have combined canopy cover of about 20% and heights of 2 to 4.5 feet (0.5 to 1.5 meters). Seedlings and saplings of large tree species such as octopus tree (Schefflera actinophylla) and African tuliptree (Spathodea campanulata) are often present.

Pathway 2.1A
Community 2.1 to 2.2

Kikuyugrass/common vetch

Hilograss - common carpetgrass

Community phase 2.1 degrades to community phase 2.2 by continuous grazing that weakens preferred kikuyugrass, pangolagrass, and legumes in relation to less desirable forage species such as Hilograss (Paspalum conjugatum), common carpetgrass (Axonopus fissifolius), and sedges. Undesirable forbs such as narrowleaf plantain (Plantago lanceolata) also increase under these conditions.

Pathway 2.2A
Community 2.2 to 2.1

Hilograss - common carpetgrass

Kikuyugrass/common vetch

Community phase 2.2 can be reconverted to phase 2.1 by prescribed grazing. A prescribed grazing plan provides for intensive but temporary grazing of pastures that ensures that cattle consume some low-value forage species along with preferred forages and allows preferred forages time to recover from defoliation. Kikuyugrass is very competitive and adapted to grazing and is able to recover with proper management. The grazing plan may require splitting the herd, creating additional water sources, and creating multiple pastures by cross-fencing.

Pathway 2.2B
Community 2.2 to 2.3

Hilograss - common carpetgrass

Strawberry guava/hilograss - common carpetgrass/scaly swordfern

Community phase 2.2 degrades to community phase by long-term continuous grazing. Remnant kikuyugrass, pangolagrass, and forage legumes are further reduced in abundance and replaced by low-value forage grasses. Weedy forbs, blackberries, and shrubs begin to increase.

Pathway 2.3A
Community 2.3 to 2.1

Strawberry guava/hilograss - common carpetgrass/scaly swordfern

Kikuyugrass/common vetch

Community phase 2.3 can be converted to phase 2.1 by a combination of weed control and prescribed grazing. Weeds such as introduced raspberries and sourbush are not controllable by domestic livestock and must be killed with herbicide. The grazing prescription will require removal of livestock from the pasture until kikuyugrass has been reestablished adequately to support grazing. Kikuyugrass may need to be resprigged into the grassland. Thereafter, the grazing plan may require splitting the herd, creating additional water sources, and creating multiple pastures by cross-fencing.

State 3
Tree Plantation with Exotic Understory State

This state has its origin in sites that were cleared of native forest in the mid- to late-20th century and planted to exotic timber species that were considered to be more valuable and useful than native forest species. More recently, previously cleared areas have been planted to timber species. In either case, invasion of the understory by weedy introduced species is a likelihood in most locations. Once established, this state has little or no tendency to transition to another state.

Community 3.1
Exotic timber species/princess flower/kahila garland lily (kahili ginger)

Figure 14. Tree plantation with mostly exotic understory. 3/13/09 D Clausnitzer generic photo

This community is typically managed for long term economic returns. Many introduced timber species will potentially grow well in the environment of this ecological site, where they may be free of pests that are present in their native habitats. Many older examples of this phase have not received ongoing management since their establishment.

Forest overstory. Timber species that were established in the past are red gum (Eucalyptus robusta), toon or Australian redcedar (Toona ciliata), tropical ash (Fraxinus uhdei), sugi pine (Cryptomeria japonica), and redwood (Sequoia sempervirens). Some areas have been planted to native koa (Acacia koa).

Other valuable species can be planted, for example African mahogany (Khaya senegalensis), Honduran mahogany (Swietenia macrophylla), and Spanish cedar (Cedrela odorata). Still other species may be grown in this ecological site.

Koa is a valuable, fast-growing native tree that can be planted here. It is much more likely to thrive at elevations higher than about 1500 feet (460 meters); lower elevation plantings are often subject to diseases. Feral and domestic animals must be fenced out of koa plantations for enough years to allow the trees to attain a stature at which animals are unable to push down and eat them. Trampling of koa’s shallow roots and eating the trees’ bark can remain a problem for a longer time. There are examples of adequately mature koa stands being maintained along with careful cattle grazing in silvopastures.

Forest understory. Common understory species are strawberry guava (Psidium cattleianum), kahili ginger (Hedychium gardnerianum), Koster’s curse (Clidemia hirta), and glorybush (Tibouchina urvilleana). These species grow very densely and are difficult to control.

Kikuyugrass can grow beneath timber trees if shade is not excessive.

State 4
Native Forest with Invaded Understory State

This state consists of one community phase. It arises by invasion by introduced species of intact native forest (the Reference State) or, in some cases, of native overstory stands from which the original understory has been cleared. Native species are unable to regenerate in the highly competitive understory of introduced plants and eventually die out. With time, large introduced tree species will emerge to replace the native overstory trees and form a new overstory. When this last step has occurred, the site will have transitioned to State 5, Invaded Overstory and Understory State. Disturbance of the soil and direct damage to native understory plants by introduced ungulates, particularly pigs and cattle, will speed the transition to this state by killing native plants and by creating better germination sites for introduced species. Restoration to the Reference State or a facsimile of it is possible by fencing the site, removing all ungulates, applying herbicides, and replanting native species when needed. Restoration efforts will be affected by the degree of invasion by introduced species and by the particular species that have invaded the site. Long term weed management and fence maintenance will be necessary.

Community 4.1
`Ohi`a lehua - strawberry guava/princess flower/kahila garland lily (kahili ginger)

Figure 15. Native forest with exotic understory. 1/11/06 D Clausnitzer MU111

Figure 16. Native trees with glyphosate-killed strawberry guava. 3-13-09 D Clausnitzer generic photo

Figure 17. Desmodium intortum invaded understory. 6/28/06 D Clausnitzer MU110

The community has an intact or diminished overstory of large ohia lehua and/or koa trees with a dense understory of introduced shrubs, ferns, vines, grasses, and small trees. Most native species are unable to regenerate in this plant community and eventually die out.

Forest overstory. The overstory consists of ohia lehua (Metrosideros polymorpha) and/or koa (Acacia koa).

Forest understory. Secondary canopy native species are usually somewhat diminished or nonexistent. Kopiko or wild coffee (Psychotria spp.) sometimes remains in the secondary canopy.

The only native species remaining in the lower canopy levels are a few hapuu (Cibotium glaucum) or hapuu li (Cibotium menziesii), traces of small kopiko (Psychotria spp.) trees, some peperomia (Peperomia spp.) at ground level, an occasional ieie vine (Freycenetia arborea), and a few patches of uluhe or Old World forkedfern. Some small native fern species may be found growing on trees.

The understory is usually dominated by a nearly impenetrable stand of strawberry guava or waiawi (Psidium cattleianum), which can be 10 to about 30 feet (3 to 9 meters) tall. Other species indicated on the table grow sparsely beneath the strawberry guava or fill in gaps between it.

State 5
Invaded Overstory and Understory State

This state is comprised of one community phase dominated by introduced species in both the overstory and understory. Remnant individuals of a few native species may persist. This state might be considered a dead end as far as further succession or transition to another state. Restoration to a facsimile of the Reference State could probably be done with expensive and intensive practices followed by long-term weed management. The site would need to be cleared of all vegetation except any remnant native species, which essentially would represent a transition to State 2 Grassland. From State 2, further restoration could be pursued to State 1 Reference. Clearing of the site followed by establishment of an overstory of noninvasive, introduced timber trees with a native understory as an intermediate step to native forest restoration may be done.

Community 5.1
Strawberry guava - octopus tree/princess flower - soapbush

Figure 18. Exotic species-dominated forest. 5/10/06 D Clausnitzer MU111

It is possible that shifts will eventually occur in the introduced species that dominate the site, particularly if competitive, tall-statured tree species are present. This would change the mix of species present and may affect soil characteristics such as nitrate availability or organic matter decomposition, but would not represent a transition to another state. Sites that are completely dominated by dense stands of strawberry guava typically show no indications, such as death or partial death of stands or emergence of potentially taller tree species, of yielding to change in the foreseeable future.

Forest overstory. Depending on local seed sources, invasive trees of moderate stature including strawberry guava (Psidium cattleianum), christmasberry (Schinus terebinthifolius), or common guava (Psidium guajava) can dominate a given site initially, but strawberry guava generally becomes dominant over time. Strawberry guava is typically the dominant tree species because it invades sites by seeds spread by pigs and reproduces vegetatively by root suckers. Strawberry guava can dominate a site for years because of the dense shade it produces and the competitive advantage conferred by its very dense root system.

Taller statured introduced trees including silkoak (Grevillea robusta), albizia or peacocksplume (Falcataria moluccana), and octopus tree (Schefflera actinophylla) could potentially emerge through the canopy of moderate stature species.

A few remnant ohia lehua trees often remain as emergents above the canopy of introduced species, but seedlings or saplings are unlikely to be present.

Forest understory. The tree overstory species are highly competitive and produce dense shade. A variety of introduced understory species is often present but in small numbers. Typical species include Koster’s curse or soapbush (Clidemia hirta), kahili ginger or Kahila garland-lily (Hedychium gardnerianum), and some shade tolerant grass species.

Strawberry guava can grow under shady overstories. Common guava eventually dies out when overtopped by a dense overstory.
Scattered individuals of remnant native species such as kopiko (Psychotria spp.), hapuu (Cibotium glaucum), and uluhe (Dicranopteris linearis) may remain in the understory.

State 6
Tree Plantation with Native Understory State

This state is comprised of one community phase dominated by introduced timber or native koa trees. It results from clearing the original native forest, often without fundamentally altering the soil, and planting introduced trees or koa. When the surrounding area remains as native forest with few weeds, native species gradually repopulate the plantation site. This state has its origin in sites that were cleared of native forest in the mid- to late-20th century and planted to exotic timber species that were considered to be more valuable and useful than native forest species. Some of these plantations were deep in the native forest and so not near major sources of introduced weeds.

Community 6.1
Koa or exotic timber species/hapu`u/bristle basketgrass/alpine woodfern

Figure 19. Old eucalyptus plantation with native understory. 5/10/06 D Clausnitzer MU112

This community is typically managed for long term economic returns. Many introduced timber species will potentially grow well in the environment of this ecological site, where they may be free of pests that are present in their native habitats. Many older examples of this phase have not received ongoing management since their establishment. The eventual condition of this community phase depends on the tree species that was planted and now dominates the overstory and, if some weeds are present, ongoing management to control them. Details of every possible scenario are not known.

Forest overstory. Timber species that were established in the past are red gum (Eucalyptus robusta), toon or Australian redcedar (Toona ciliata), tropical ash (Fraxinus uhdei), sugi pine (Cryptomeria japonica), and redwood (Sequoia sempervirens). Some areas have been planted to native koa (Acacia koa).

Other valuable species can be planted, for example African mahogany (Khaya senegalensis), Honduran mahogany (Swietenia macrophylla), and Spanish cedar (Cedrela odorata). Still other species may be grown in this ecological site.

Koa is a valuable, fast-growing native tree that can be planted here. It is much more likely to thrive at elevations higher than about 1500 feet (460 meters); lower elevation plantings are often subject to diseases. Feral and domestic animals must be fenced out of koa plantations for enough years to allow the trees to attain a stature at which animals are unable to push down and eat them. Trampling of koa’s shallow roots and eating the trees’ bark can remain a problem for a longer time. There are examples of adequately mature koa stands being maintained along with careful cattle grazing in silvopastures.

Forest understory. The tree ferns hapuu (Cibotium glaucum) and hapuu ii (C. menziesii) are common. Common secondary and tertiary canopy trees are kopiko (Psychotria spp.), kolea lau nui (Myrsine lessertiana), pilo (Coprosma spp.), olomea (Perrottetia sandwicensis), olapa (Cheirodendron trigynum), and mamaki (Pipturus albidus). Ieie vines are present on the ground and climbing on introduced and native trees. Fern species such as io nui (Dryopteris wallichiana) and hoio kula (Pneumatopteris sandwicensis) are found under introduced and native timber species. Under koa plantations, ohia lehua are able to grow because koa canopies allow sufficient light to penetrate to the ground. However, redwood plantations contain very few native species other than very hardy species such as io nui (Dryopteris wallichiana).

Transition T1A
State 1 to 2

State 1, Reference State, can transition to State 2, Naturalized Grassland, by clearing the forest with heavy machinery or by gradual clearing by allowing cattle access to the forest. Cattle eventually eat or destroy understory ferns, forbs, shrubs, and saplings, opening up the forest so that forage grasses will thrive. On lava substrates, underlying lava rock often is ripped and crushed by heavy machinery to produce Udarents (sandy, organic) soils. Ripping and crushing produces some fine mineral particles and small, abundant gaps between the rock fragments. However, about 50% of the soil organic matter may be lost in the process due to exposure to air and higher temperatures.

Transition T1B
State 1 to 3

State 1 Reference State can transition to State 3 Tree Plantation with Exotic Understory by mechanical removal of the original forest overstory and understory followed by planting of introduced timber species or koa. This practice was common in Kona in the mid-20th century. When the surrounding area is infested with introduced weeds such as Koster’s curse (Clidemia hirta), strawberry guava (Psidium cattleianum), or kahili ginger (Hedychium gardnerianum), those species will invade the site and dominate the understory unless controlled by herbicides. Restoration of native forest would be difficult but possible in koa plantations.

Transition T1C
State 1 to 4

State 1 Reference State can transition to State 4 Native Forest with Invaded Understory by gradual replacement of the understory by introduced shrubs, vines, and small trees that outcompete the native understory species. This process is accelerated by foraging by ungulates and rodents that disturbs the soil surface and directly destroys native plants and prevents their regeneration.

Transition T1D
State 1 to 6

State 1 Reference State can transition to State 6 Tree Plantation with Native Understory by mechanical removal of the original forest overstory and understory followed by planting of introduced timber species or koa. This practice was common in Kona in the mid-20th century. When the surrounding area contains native understory species and is fairly weed-free, native plants such as tree ferns, ieie vines, native ferns, and small native trees reestablish themselves beneath the canopies of many exotic timber species. An exception is redwood plantations, which appear to exclude establishment of most native plants. The ultimate plant community that will develop over time is unknown.

Restoration pathway R2A
State 2 to 1

It is possible to restore a facsimile of the Reference State from Naturalized Grassland. Weed control must be applied to grass species and the many opportunistic plant species that will invade the site. Increased shade from trees growing on the site causes a shift from C4 (warm-season) grass dominance (typically kikuyugrass or pangolagrass) to C3 (cool-season) shade-tolerant grasses (typically meadow ricegrass). This meadow ricegrass layer can be almost as dense and detrimental to establishment of native plants as kikuyugrass. Attempts have been made to suppress meadow ricegrass by planting native shrubs and tree ferns that produce dense shade near the ground and litter that covers the grass. Weed control will be a perpetual process to capture and maintain the site, with the intensity of control depending on the proximity of weed seed sources. Foraging ungulates, both domestic and feral, must be excluded from the restoration site, but domestic ungulates are useful to initially reduce grass cover and afterward to manage vegetation outside the restoration site perimeter. Extensive planting of native species would follow. On sites where soils have been converted to Udarents by ripping and crushing by heavy machinery, forest restoration may be more problematic due to the dramatically changed soil conditions. Udarents appear to be a very favorable seedbed for alien weeds.

Transition T2A
State 2 to 3

This state may transition to State 3 Tree Plantation with Exotic Understory by herbiciding kikuyugrass, removing ungulates, and then planting introduced timber species. Gradual weed invasion creates an understory dominated by introduced trees, shrubs, grasses, and ferns. It may be possible to develop silvopasture systems that would combine timber production with cattle grazing; this system would control weeds and maintain an understory of introduced forage grasses.

Transition T2B
State 2 to 5

Abandonment of State 2 Naturalized Grassland community 2.3 leads to continued invasion by, and rapid growth of, introduced tree species leading to transition to State 5 Invaded Overstory and Understory.

Restoration pathway R4A
State 4 to 1

It is possible to restore a facsimile of State 1 Reference from State 4 Invaded Understory. Before restoration of native plants, introduced understory plants must be eliminated by herbicidal weed control practices, and ungulates must be excluded from the restoration site by a suitable fence. Native species that have been eliminated or greatly reduced in numbers must be restored by replanting. Biodegradable mulch such as cardboard covered with plant litter is very useful for weed control around replanted native species. Long-term control of weeds will be necessary.

Transition T4A
State 4 to 2

State 4 Invaded Understory State may be restored to State 2 Naturalized Grassland State by mechanical clearing of introduced and remnant native understory plants; native overstory trees may be harvested for timber, destroyed, or left for shade. If leaving large native trees for shade, care must be taken to not damage near-surface roots within about 20 feet (6 meters) of the trees. Introduced pasture grasses may then be seeded or sprigged into the site. Herbicide applications will be necessary before and during pasture establishment to control reemerging weed species.

Transition T4B
State 4 to 5

The large native ohia lehua and koa trees that form the overstory of State 4 Invaded Understory State are unable to successfully regenerate due to the very dense, shady understory of introduced species. Eventually the large native trees die and are replaced by introduced tree species, which is a transition to State 5 Invaded Overstory and Understory.

Restoration pathway R5A
State 5 to 2

State 5 Invaded Overstory and Understory may be restored to State 2 Naturalized Grassland by mechanical clearing of overstory and understory vegetation. Introduced forage grasses may then be seeded or sprigged into the site. Herbicide applications will be necessary before and during establishment of grasses to control reemerging weed species.

Restoration pathway R6A
State 6 to 1

Where the overstory is koa, it is probable that this state would eventually return to State 1 Reference if not harvested. Where the overstory consists of introduced tree species, some of which successfully reproduce in the understory, the eventual trajectory of this plant community is unknown.