Successional Trends in the Coastal and Lowland Forestof Mauna Loa and Kilauea Volcanoes, Hawaii!

I. A. E. ATKINSON2

ABSTRACT: Three trends in forest succession are described from the coastal andlowland lava flows «1,000 feet) of Mauna Loa and Kilauea in Hawaii. All beginon bare rock in a region of high rainfall (75 to 150 inches). One trend is incoastal forest and involves the replacement of M etrosideros polymorpha vegetationby Pandanus tectorius forest. The other trends occur inland and give rise to Metro-,sideros polymorpha and M etrosideros polymorphajDiospyros [errea forests with in400 years. No consistent differences in successional trends were observed betweenpahoehoe and aa flows. Seasonal dis.tribution .of rainfall wa~ consid~red to be im­portant in differentiating the M etroslderosjDlOsPYros su:cesslOn, wh.I1e exposure towind-carried salt may different iate the Pandanus succession . There IS need to pro­tect representative areas of these forests for future study.

THIS PAPER gives information on some of thesuccessions occurring during the first 400 yearsof forest development on aa and pahoehoe flowsof Mauna Loa and Kilauea. The earliest stagesin successions on Hawaiian lava flows havebeen reasonably well documented (Forbes,191 2; MacCaughey, 1917; Robyns and Lamb,1939; Skottsberg, 1941 ; Doty and Mueller­Dombois, 1966; Smathers, 1966; Doty, 1967) ,but little has been written about later stages,particularly in regions of high rainfall. Theobservations recorded here are concerned withcoastal and lowland flows less than 1,000 feetin altitude.

DESCRIPTION OF AREA STUDIED

Location

The area studied (Fig. 1) covers parts of thelower slopes (0-1,000 feet) of both MaunaLoa (13,677 feet) and Kil auea (4,090 feet).It includes: (1) the eastern slopes of MaunaLoa that lie south and southeast of Hilo, and(2) the northern and southeastern slopes ofthe Puna rift zone of Kilauea within 9 milesof Pahoa.

1 Manuscript received N ovember 28, 1969.2 Department of Agronomy and Soil Science, Uni­

versity of H awaii. Present Address: Botany D ivision ,D epartm ent of Scientific and Ind ustr ial Research, Pal­rnerston N orth . New Zealand .

387

Clim ate

Climatic data for the area have been given byBlumenstock and Price (1967) . Mean annualtemperatures vary from 73.1° F near sea level(Hilo airport) to 69.9° F at 1,000 feet, basedon a temperature lapse rate of 3.5 ° F per thou­sand feet (Mr. Saul Price, U. S. Weather Bu­reau, personal communication). Near sea level,mean summer and mean winter temperaturesare 74.8° and 71.4° F, respectively. At 1,000feet, approximate mean summer and wintertemperatures are 71.3° and 67 .9° F. The meanvariation between warmest (August) and cold­est (February) months is between 5° and 6 ° Fand probably never exceeds 9 ° F. The area isfrost free.

At sea level, mean annual rainfall increasesnorthward from about 75 inches near Kaimuto 136 inches at Hilo airport. Inland at 1,000feet altitude, annual rainfall is more than 140inches in the Puna rift region and more than150 inches on Mauna Loa. Rainfall is ratherunevenly distributed, with the wettest month,December or March, often receiving more thantwice the rainfall of the driest month , June . Inareas where monthly averages are all above 10inches, there may be occasional months withonly 1 or 2 inches of rain . Rainfall intensitiesin excess of 9 inches in 24 hours occur onceevery 2 or 3 years at most localities. (Blumen­stock and Price, 1967) . Average relative hu­midities are between 70 and 80 percent.

388 PACIFIC SCIENCE, Vol. 24, July 1970

The eastern slopes of Mauna Loa are exposedto the northeasterly trade winds which blowmore than 70 percent of the time. Storms areinfrequent.

Geology

The surficial lava flows of the area areeither late Pleistocene or Recent in age and in­clude both pahoehoe and aa types of lava. Those

KA'UA I

f----\------\~---+---_+---+--_____i 22° N

OAHU

N

t

MOLOKAIHonolulu

STATE OF HAWAII

~'<----t--t----------- 40'

10 '

10_c=_c=..Ii:::::::== = = :::J MIL ES

/o

FIG. 1. l ocation of area studied and positions of sampling sites.

Successional Trends in Hawaiian Forests-ATKINSON 389

of Mauna Loa belong to the Kau Volcanic Se­ries and those of Kilauea to the Puna Series(Stearns and Macdonald, 1946) . The only datedflows in th e study area are the 1750, 1840, and1955 flows of Kilauea. All of these originatedas flank eruptions from the Puna rif t zone. Theage of the flow tentatively dated as 1750 isuncerta in, the only reference being that ofHitchcock (1911, p. 164) who gives the period1730 to 1754 as the time of an eruption atKaimu. The 1750 date used here , is that givenon the geologic map of H awaii (Stearns andMacdonald , 1946). All other flows in the regionare prehistoric (i .e., earlier than 1750) . Lavasof the area studied belong to the tholeiitic suitedefined by M acdonald and Katsura ( 1962) andinclude olivine basalts, basalts, and oceanites(Macdonald and Katsura, 1964) .

Patches of Pahala ash, dated from charcoalas last glacial (Rubin and Berthold, 1961) , oc­cur locally, but soils from this mater ial are nowlargely under sugar cane. Pum ice deposits, asso­ciated with cones and craters, cover small areas(Stearns and Macdon ald, 1946 ), and historiceruptions of Mauna Loa and Kilauea havespread small amounts of ash and dust over wideareas of Hawaii Island (Wentworth, 1938).However, profi le observations on the flows stud­ied show tha t the contribution of ash to soilform ation is small. Thus the successional trendsdescribed below are essentially those on ash­free lava.

T op ography and Soils

Because of their youth, lava flows of the areaare undissected and witho ut permanent streams.Their highly permeab le nature restricts surfacewater to small unfissured areas on a few pahoe­hoe flows. General slopes are long and gen tle,averaging about 30 to 4 0 on Mauna Loa and10 to 4 0 in the Puna rift region of Kilauea. Theland surface is usually undulating except wherebroken by the more craggy surface of recent aaflows.

Soil development on the flows studied is re­stricted to a surficial layer of organic matter,o to 2 cm in depth, overlying weathering basalt.Depending on the age of the flow, some accu­mulation of organic matter and mineral par­ticles has occurred in cracks between rocks.Cline (1955) mapped the soils of the later

prehistoric and historic flows as lithosols. Ac­cording to the U. S. Compre hensive Classifica­tion these soils are entisols and lithic folists inthe order histosols (Soil Survey Staff, 1968) .

Vegetation and Land Use

Forest domina ted by M et1'Osideros polymor­pha covered most of the study area in the past,but much of it has now been replaced by settle­ments and cultivated crops. A general descrip­tion of the present vegetation of the area isgiven by Fosberg ( 1961) . Doty and Mueller­Dombois (1966) described the M etrosiderosfores ts on prehistoric flows adjacent to two flowsof the 1955 Kilauea erup tion: the Kii flow at100 feet altitud e and the Kamai li flow at 900feet altitude (Fig. 1) .

The vegetation pattern of the early 19th cen­tury can be inferred from surviving stands . Adense scrub of Scaevola taccada and H ibiscustiliaceus grew along the shoreline. Behind this,Pandanus tectorius forest, up to 10 meters high,domin ated the coastal fringe, and this changedwith increasing distance from the coast to aPandanus-M etrosid eros forest that extendedhalf a mile or more inland. Further from thesea, Met1'Osideros forest, up to 30 meters high,formed the main plant cover, its height andunderstorey composition varying with age. Thisgeneral pattern would have been broken inplaces by clearings of the early Hawaiians, wherea number of introduced plants such as coconutwould have grown.

In the present vegetation of some prehistoricflows, the M etrosid eros trees are smaller andmore widely spaced on pahoehoe flows than theyare on aa flows of similar age. Between the trees,and sometimes growi ng over them, are densethickets of the fern Dicranopteris linenri s. Onvery recent flows the whitis h-colored lichenStereocaul on oulcani is sometimes abundant andthe only common tree seedling is M etrosideros.Int roduced species are uncommon on such flows.

Land clearing, fires, and introduced animals ,particularly pigs and cattle , have modified ordestroyed the original vegetation in many places,allowing several introduced plants to becomewidespread. The most abundant are Psidiumguajava, Plucbea odorata, and Melastoma mal­abathriwm. In the Puna district, large areas ofMetrosideros/Dicranopteris fernland have been

390

burned, and the regrowth is dominated bygrasses, particularly the introduced Andropogonoirginicus. Also, plantations of coconut, papaya,banana, and coffee are growing here on recentlava flows. On late prehistoric flows of MaunaLoa, north of Olaa, additions of volcanic ashand fertilizers have made possible the establish­ment of a l arge macadamia nut farm .

ME THODS

The flows sampled in this study were chosendur ing the course of an investigation into meth­ods of aging lava-flow ecosystems (Atkinson,1969) . Sampl ing of the vegetation consideredin th is paper was restricted to seven sites onfive flows of either late prehi storic or knownage, and located at altitud es useful for the prob­lem of determining ages. These sites are consid­ered to be representati ve of the flows sampled .However, the trend s discussed in this paper arebased on observations made on many flows inaddition to those sampled.

The exact position of each sampling site wasdetermined by sighting across the general slopeof the particular flow chosen to a distant object.Following th is line, 50 paces were stepped offfrom the edge of the flow to clear the samplefrom conditions peculiar to the flow edge. Thesite was then checked to see if (1) its generalslope was less than 10 percent (so that slopewould be relatively constant throughout sam­pling ) , and (2) its surface and vegetation wererepresentative of the flow in that area. If thesecondi tions were not met, another 50 paces weretraversed, and this procedure repeated if neces­sary until a suitable site was reached. In prac­tice, no pacing repetitions were needed. At thepoint where pacing ended, a 100-meter linetransect was oriented in the same direction, thatis, across the general slope of the flow.

At each site, 10 or more trees within 2 me­ters of the line transect were measured forheight (using abney level and eye estimates)and diameter at breast height (d.b.h.), that is,1.4 meters above the grou nd. The stem diameterof trees less than 1.5 meters high was measuredhalfway up the stem. A tree volume index wasobtained from the relationship: tree volumeindex = heigh t X basal area where basal area= rrr2 and r = d.b.h.y'z.

PACIFIC SCIENCE, Vol. 24, July 1970

The term callopy was used to denote the plantcrowns that form the skyward surface of thevegetation and it was applied to all types ofvegetation, for example, lichenfield , fernla nd,or forest. The percentage of ground area cov­ered by the canopy (canopy cover) and thepercentage covered by each species in the canopywere measured by recording the plants appearingvertically above 50 points spaced 2 meters apartalong the 100-meter transect. For shor ter vege­tation, such as lichenfields, the 50 points werespaced at 60-cm intervals along a 30-meter tran­sect.

The pter idophyte and spermatophyte speciesrepresented by three or more plants were listedfor each site in an area of about 50 X 50 me­ters oriented parallel to the line transect (seeApp endix) .

Because of the variety of vegetation structureencounte red on Hawaiian lava flows a conveni­ent naming system is desirable. Terms such asforest, lichenfield, and rockland are used hereaccording to whichever type of growth-fo rm orground material constituted the uppermost sur­face. Th e term treeland, rather than forest, isused for a tree-dominated vegetation if the can­opy cover of trees was less than 80 percent.The type of forest or fernland is designa tedfrom the generic names of the major canopyspecies, that is, those with canopy cover equalto or greater than 20 percent. A slant line (/)between generic names indicates that the firstspecies (e .g., Metrosidel'os) forms a separatestratum above the second species (e .g., Dicran­opteris ) . W hen necessary, a hyphen is used toseparate species in the same stratum. This nam­ing system enables one to convey informationon both composition and structure of the vege­tation.

SUC CESSIONAL TR ENDS

Three main trends in forest succession wererecogn ized, all beginning on bare lava.

1. R OCKLAN D ~ M etrosideros T REE LAND ~

Pandanu s FOREST

This succession occurs in a quarter-mile-widecoastal zone on pahoehoe and aa flows havingmore than 70 inches of annual rainfall. Ferns(Nephrolepis sp.) establish in cracks, and the

Successional Trends In H awaiian Forests-ATKINSON 391

METERS7.5

o

2 .5

5 .0

oFIG . 2 . Profile diagram of M et/'oside/'os rockland on the 1840 aa flow of Kilauea (1840 L sampling site,

40 feet altitude) . M = M etrosideros polym orpba, N = N epbrolepis birsia ul«, S = Scaevola taccada.

2 .5

5 .0

METERS7.5

TABLE 1

• N umber of plants sampled = 45.

H EIGHT-CLASS D ISTRIBUTIO N OF M etrosid erospolym orpba ON TH E 1840 KI LAUE A

LAVA -FLOW AT 40 FEET ALTITUDE

lichen Stereocaulon oulcani enters on boulderswithin 5 years of flow formation. Metrosiderospolymo rpha is the pion eer tree species, appear­ing within 10 years, and a rockland with scat­tered trees develops as on the 1840 flow (Fig.2) . The heigh t-class distribution of Metro­sideros from this same site (Table 1) showsthat young plants are still entering the com­munity even after 120 years. Pandanus tectoriusis absent from the 1840 and 1750 flows. Thusit must sometimes be more than 200 years be­fore this species appea rs in the succession. How­ever, on late prehistoric flows located betweenthe 1750 flow and the 1960 Kapoho flow, ju­venile Pandanus can be seen among the Metro­sideros on sites which are apparently no dif-

ferent from the 1840 and 1750 flows, apart fromtheir greater age (Fig. 3). On older prehistoricflows, both between and south of these flows,Pandanus-M etrosideros forest occurs. In ad­vanced stages of the succession, Metrosiderosapparently decreases and may disappear alto­gether, as for example on a prehistoric flownorth of Kapoho (Fig. 4).

2. ROCKLAND ---7 Dicranopteris FERNLAND ---7

M etrosideros/ D icranopteris TREELAND---7M etrosideros FOREST

This is the most widespread trend of succes­sion on aa and pahoehoe flows below 1,000 feetaltitude . The earliest stages have been detailedby D oty and Mueller-Dombois (1966) andDoty ( 1967) . M ats of Stereocaulon are some­times prominent on young flows, particularlywhere the porosity of individual rocks is high.During intermediate stages of the succession,there is wide variation in the proportions ofDicranopteris linearis and M etrosideros formingthe canopy, and all gradations from fernlandto treeland can sometimes be found on the sameflow.

Metrosid eros seedlings are absent in the tree­land, possibly because of the dense fern cover.Increase in Metrosideros cover appears to betaking place by lateral spread of crowns and re­sprouting from pros trate branches. Judged by

131613201622

PE RCENTAGE OF TOTAL*

0-11-22-33-44-5>5

H EIGHT CLASS

(meters)

392 PACIFIC SCIENCE, Vol. 24, July 1970

FIG. 3. Juvenile Pandanus tectorius growing in Metrosideros treeland on a late prehistoric aa lava flowsouth of Kapoho (50 feet altitude) .

METERS

12 .5

METERS 10.010.0

7.57.5

5.05.0

252 .5

00

FIG. 4. Profile diagram of Pandanus forest on a prehis toric aa flow north of Kapoho (90 feet alti tude).A =Aleurites molueeana, An =Asplenium nidus, Me =Morilzda citriiolia, P = Pandanus tectorius, Pg =Psidium guajat'a.

Successional Trends In Hawaiian Forests-ATKINSON

METERS

10.0

393

METERS

10 .0

7 .5

5 .0

2. 5

FIG. 5. Profil e diagram of M etl'osideros/DiCl'anopteris treeland on the 1840 aa flow of Kilauea (18 40H sampl ing site, 650 feet altitude. D =D icranopteris linearis, M =M etrosideros polymorpba.

the vegetation of the upper half of the 1840flow, the treeland stage of this succession canbe reached within 120 years (Table 2 and Fig.5) . Replacement of the treeland by M etrosiderosforest is inferred from the presence of M etro­sideros stands on older aa flows nearby. How­ever, there are extensive prehistoric pahoehoeflows in the Pahoa district which are still in theMe trosideros/ Dicral1opteris treeland stage. Evenallowing for past fires, it appears that the rateof succession on pahoehoe is extremely slow.

Stages in th is succession can be found wherethe rainfall is 80 to 140 inches per annum, butwith higher rainfall, tree ferns ( Cibotimn spp .)form an increasing proportion of the canopyand the succession moves toward M etrosideros/Cibotium forest. Some Cibotium is present ona prehistoric site sampled at 300 feet altitudenear the Stainback Highway south of Hilo, the"Lower Stainback" site (Fig. 1 and Table 2) .The rainfall here is approximately 140 inches,and the M etrosideros stand sampled has an un­derstorey of Cibotium tree ferns , Psidium gtta­java, and Coffea sp. The mean tree volume forth is sample is smaller than that from some his­toric flows (Table 2) , and this, together withthe rather close spacing of the M etrosiderostrees, suggests that the Lower Stainback forestmay be secondary in origin.

In the very high rainfall zone above 1,000feet altitude (> 150 inches per annum) on thenortheastern slopes of Maun a Loa, the succes­sional trends are more complex , with many spe­cies entering the canopy besides Cibotium treeferns.

3. ROCKLAND ~ M etl'osideros FOREST~M etrosideros/Diospyros FOREST

Stages in this succession were found only onaa flows below 1,000 feet in the western Punarift district where mean annual rainfall is 110inches or less. As with the other trends de­scribed, Metrosideros polymorpha is the pioneertree species, but in this succession the fernD icranopteris appears to be unimportant. A sitesampled on the 1750 flow (Fig. 6) illustratesan intermediate stage where Diospyros [errea isstill only an upper tinderstorey species. That itwill ult imately form part of the canopy can beinferred from the absence of both M etrosiderosjuveniles (i .e., seedlings and saplings) and re­sprouts, and the presence of juvenile Diospyrosof various heigh ts. Th is particular site was atan altitude of 990 feet. At 300 feet altitude onthe same flow, where a closed forest canopy hasnot yet developed , D iospyros was absent.

This community shows the highest rate ofgrowth among the historic stands sampled (Ta-

TABLE 2

M EAN T RUNK DIAMETERS,TR EE V OLUMES, AND CANOPY COVEROF V EGETATION SAMPLED ON HAWAIIAN LAVA FLOWS

I.>J\0~

MEAN MEAN CANOPY COVER %ANNUAL NO. OF MEAN TREE

ALTITUDE RAINFALL TYPE OF TREES D.B.H . VOL. INDEX M ell"o- D icranop-LAVA FLOW (feet) (inches) VEGETATION SAMPLED (em) ( cu dm ) TOTAL sideros teris Cibotium

Ki lauea 195 5 930 100 Stereocaulon 10 0.5 0.05 80 <1 0 <1lichenfield

Kil au ea 1840 H 650 130 M etrosideros/ 10 5.7 21. 5 100 52 48 0D icranopterls

treeland

Kilauea 1840 L 40 115 M etrosidero s 20 5.0 19 .5 72 24 0 <1rockland

K ilauea 1750 H 99 0 110 M etrosideros 10 63 .0 7,545 100 76 0 12 'i:lforest >

K ilau ea 1750 L 300 M ett'osideros 26 .0 1,1 49(')

90 10 70 10 0 < 1 -"'!'ltr eeland -o

Mauna Loa Prehistor ic 300 140 M etrosid eros 10 27.0 90 1 100 72 0 16CI'l

Low er forest oStainback -tTl

Kilau ea Preh ist oric 90 100 Pandanus 10 15.0 195 100 0 0 0 Zflow north forest

(').tTl

of K apoho-<1?-N.~

'-<C-<.....\0-...J0

Successional Trends 10 H awaiian Forests- ATKINSON 395

5 .0

10.0

o

15.0

METE RS20.0

5.0

o

15.0

10.0

20.0

METERS

D

FIG. 6. Profile diagram of M etrosideros forest on the upper 1750 aa flow of Kilauea ( 1750 H sampling site,990 feet alt itude) . An =Asplenium nidus, D = Diospyros [errea, Fa =Freycinetia arborea, M = Metrosiderospolymorpba, Ph = Psychotria hawaiiensis.

ble 2) . At the time of sampling , logging ofsuch stands was taking place in adjacent areas.

DISCUSSION

Trends of Succession

An important question is how the three trendsdescribed become differentiated from each other.Within the rainfall range stud ied, 75 to 150inches per annum, succession to Metrosiderosforest is the most general trend. The coastaltrend towards Pandanus forest may possibly berelated to the tolerance of Pandanus tectorius towind-carried salt. Th e species was found up to1.6 miles inland from the coast (north ofKaimu ) . W hy Pandanus is generally restr ictedto a much narrower coastal belt is not known.It is surprising that Pandanus does not enter thesuccession earlier than it does, since there areoften bare areas among Metrosideros trees thatappear suitable for Pandanus establishment. Pos­sibly the relatively heavy seed limits its dis­persal. H ow much time is necessary before

Pandanus replaces the Metrosideros completelyis also unknown.

Rainfall differences may explain the diver­gence of the M etrosidel'os and MetrosiderosjDiospyros successions. Mueller-Dombois (1966)describes open Metrosiderosj Diospyros foreston slopes within Hawaii Volcanoes N ationalPark, and associates it with a summer-dry cli­mate. Summer-dry conditions may occur to someextent in the Kil auea 1750 H site (Metr osiderosforest with Diospyros understorey) where therainfall is 110 inches, but they are unlikely inthe Metrosideros forests of the Stainback area,Maun a Loa, with its 140 inches or more of rainper annum and frequ ent cloud cover. Diospyrosferrea occurs in the Stainback area but there isno indication that it will ever be an importantspecies there. Thus it can be inferred that de­crease in rainfall from 140 to 110 inches, orpossibly the reduced cloud cover associated withthis rainfall difference, has altered the trend ofsuccession fro m M etrosideros to MetrosiderosjDiospyros forest.

396

Comparison of the 1750 H site (990 feet)with the 1750 L site (300 feet altitude and 90­inch annual rainfall, Table 2) shows a reducedgrowth rate of Metl'osideros on the latter site.The forest on the 1750 flow at the lower alti­tude is still quite open with many areas of barelava. Diospyros was not present on the 1750 Lsite although open M etrosideros/Diospyros for­est does occur in still lower rainfall areas withinthe National Park. Thus, although the rate ofsuccession has been reduced in the area of lowerrainfall , there is no reason to suppose that thetrend of succession has been altered.

A second important question concerns thefuture composition of the forests described, Inthe absence of disturb ance by man or introducedmammals, the Pandanus forest appears to beself maintaining. In both Pandanus and M etro­sideros forests, wherever the canopy has beenopened by cutting, fires, or animals, there hasbeen extensive invasion of introduced plants,particularly Psidium species. Juvenile and ma­ture trees of Aleurites moluccana present amongthe Psidiam stands suggest that, in some placesat least, Alenrites will dominate these disturbedforests in the future.

In undisturbed M etrosideros forests olderthan 100 years, the absence of M etrosiderosseedlings from shaded ground ind icates a de­crease in M etrosideros cover in the future. It isnot unlikely, however, that after several cen­turies replacement of Metrosideros could bal­ance mortality. Such replacement can be effectedthrough resprouts from old trees and by theoccasional establishment of seedlings on treefern trunks.

Factors Affecting the Rate of Succession

General observations on the island of Hawaiiindicate that the most important factor influenc­ing the rate of succession on lava is availablemoisture. This is governed by rainfall andedaphic factors, particularly the size distributionof boulders and stones, and the porosity of indi­vidual rocks. These edaphic factors are of great­est importance during early stages. Thus a flowcomposed mainly of large boulders tends tohave a lower cover of Metrosideros trees thana flow containing a high proportion of stonesand fine material. Presumably, moisture stress

PACIFIC SCIENCE, Vol. 24, July 1970

on flows of coarse material is too great to allowthe Me troside ros trees to establish.

Rock poros ity influences part icularly the es­tablishment of lichens. The 1955 Kamaili flowfrom Kilauea, for example , is particularlyscoriaceous and porous, and here Stereocaulonoulcani is extremely abundant. Scoriaceous lava,with its numerous pores, can probably catch andhold lichen propagules more easily than canless porous rock.

On pahoehoe flows, the establishment ofMetrosideros app ears to be at least partly con­trolled by fissures and cracks, a point noted bySkottsberg ( 194 1) . A flow with few fissurestends to have a lower density of M etrosiderosthan a strongly fissured flow. The fissures act astraps for wind-blown dust and mineral nut rientsreleased by the weathering of the pahoehoecrust. Accumulation of th is fine material wouldincrease moisture storage. Forbes (1 912) re­marked on the fertile soil that develops in pa­hoehoe cracks. In addition to these factors ofnutrient and moisture supply, a fissure providesspace for the development of roots. Thus, eventhough the density of Me trosideros trees isusually lower on paho ehoe than on aa flows, ahighly fissured pahoehoe flow can support aM etrosideros stand of similar density to an ad­jacent aa flow of the same age.

Another effect of available moisture on thetrend of succession concerns the fern Dicran­opteris linearis. On both pahoehoe and aa flows,M etrosideros regeneration practically ceases asthis fern spreads and forms dense tangledth ickets. Establishment and growth of Dicran­opteris appears to be very dependent on avail­able moisture: on drier sites such as the lowerpart of the 1750 flow, this fern is infrequentor absent.

Representative A reas f or Future Study

There is need to protect representative areasof the communities described for future study.Although a wide range of vegetation is pro­tected in Hawaii Volcanoes National Park, thereappears to be no reserve of the coastal Pandanusforest or the M etrosideros/Diospyros forestwith a continuous canopy. The Pandanus forestsoutheast of Hilo is the lowermost forest in asequence of vegetation that, though damaged ordestroyed in places, extends with few breaks

Successional Trends in Hawaiian Forests-ATKINSON 397

from sea level to the summit of Mauna Loa at13,000 feet. There can be few places in thePacific region where such a complete sequenceof vegetation and soils can still be stud ied.

Comp arison with N ew Z ealand

It may be remarked in conclusion that in N ewZealand four species of M etrosideros are earlyentrants of successions on rocky surfaces. M . ex­celsa and M. excelsa x M . robnsta hybrids haveestablished on the late prehistoric basalt flowsof Rangitoto Island, near Auckland. M . ex celsadominates young forests on late prehistoricrhyolite flows of Mayor Island in the Bay ofPlenty . M. robusta, widespread in the N orthIsland of New Zealand, usually establishesepiphytically on other trees. This species andM . nmb ellata, widespread in the South Island ,can colon ize rocky surfaces such as fans ofcoarse debr is or rock faces left by landslips.Finally, M . Eermadecensis colonizes recent vol­canic surfaces in the Kermadec Islands.

ACKNOWLEDGMENTS

This work was funded through the HawaiiAgricultural Experiment Station and carried outdur ing tenure of a N ational Research Fellow­ship awarded by the New Zealand Government.It formed part of the author's doctoral disserta­tion in soil science submitted to the GraduateSchool, Uni versity of Hawaii.

I would like to thank Dr. 1. D. Swindale,Department of Agronomy and Soil Science,University of Hawaii, who initiated the project,and Dr. C. H . Lamoureux, Department of Bot­any, University of Hawaii , for his assistancewith plant identification and help ful criticisms.I would also like to thank Dr. Y. N . Tamimiand Dr. F. B. Thompson of the UniversityBranch Station at Hilo , Hawaii, for arrang ingtransport and facilitating all phases of the fieldwork.

LITERATURE CITED

ATKINSON, I. A. E. 1969. Rates of ecosystemdevelopment on some Hawaiian lava flows.Unpublished Ph.D. thesis, University of Ha­waii, Honolulu .

BLUMENSTOCK, D . I., and SAUL PRICE. 1967.

Climates of the states, Hawaii. Climatographyof the United States, no. 60-51. U. S. Depart­ment of Commerce, W ashington.

CLINE, M. G. 1955. Soil survey of the Territoryof Hawaii. U. S. Department of Agriculture,Soil Survey Series 1939, no. 25, 644 pp.

DOTY, M. S. 1967. Contrast between the pio­neer populating process on land and shore.Bulletin of the Southern California Academyof Sciences, vol. 66, pp. 175-194.

DOTY, M. S., and D. MUELLER-DoMBOIS. 1966.Atlas for bioecology studies in Hawaii Vol­canoes N ational Park. Hawaii Botanical Sci­ence Paper N o. 2. University of Hawaii.

FORBES, C. N. 1912. Prelim inary observationsconcerning the plant invasion on some of thelava flows of Mauna Loa, Hawaii. B. P.Bishop Museum Occasional Papers, vol. 5,no. 1, pp . 15-23 .

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APPENDIX

LISTOF VASCULAR PLANTS FOUND ON SAMPLING SITES( * indicates int roduced speci es)

SAMPLING SITES WITH ALTITUDES

Pr e- Pre-historic h istoric

1955 1840 L 1840 H 1750 L 1750 H Kapoho StainbackSPECIES ( 930 ft) (40 ft) ( 650 ft) (300 ft ) ( 990 ft) (90 ft ) ( 300 ft)

PTERIDOPHYTA

ASP!DIACEAE

Cyclosorus parasiticus(1.) Farwell +

C. iruncatus (Poir .) Farwell +ASPLENIACEAE

Asplenium nid«: 1. + +Asplenium sp. + +

BLECHNACEAESadleria cyatbeoides

Kaulf. + + +DAYALLlACEAE

*Nephrolepis birsutu la(Forst . f .) PresI + + + + + + +

GLE ICHENIACEAE

Dicranopteris linearis(Burm.) Underwoo d + +

HYMENOPHYLLACEAE

Vandenboschia cyrtotbeca(Hilleb.) Cope!. + +

LYCOPODIACEAE

Lycopodium cem uutn 1. +OPHIOGLOSSAC EAE

Opbioglossum pendulum(Presl) Clausen + +

POLYPODIACEAE

Pleopeltis th llllhergianaKaul f. +

Successional Trends In Hawaiian Forests-ATKINSON 399

APPE NDIX ( continued)

SAMPLING SITES WITH ALTIT UDES

Pre- Pre·historic historic

1955 1840 L 1840 H 1750 L 1750 H Kapoho StainbackSPECIES (930 ft ) (40 ft) ( 650 ft ) (300 Ft ) (990 ft ) (90 ft ) (300 ft)

PSI LOTAC EAE

Psilotum nudum (1. ) Beauv. + +PTERIDACEAE

Cibotium glaucum(Smith) H ook. et Am . + +

MO NOCOTYLEDON AE

CY PERACEAE

Fimbristylis cymosa R. Br. +Machaerina angustij olia

(Gaud .) Koyama +GRAMI NAE

*A ndropogon ? glomeratus(Walt.) BSP. +oplism enus birtellus(1.) Beauv. + +

LILIACEAE

Cordyline [ruticosa(1. ) Goepp. + +

Smilax sandtoicensis Kunth +ORCH IDACEAE

*Arundina bambusaejoliaLind!. + + + +

*Spetboglottis plicata B!. + + + + 'PALM AE

Cocos nucijera 1. +PANDAN ACEAE

Freycinetia arborea Gaud. + +Pandanus tectorius Park. +

DICOTYLEDONAE

ANA CARDIACEAE

*Scbinus terebintb ijoliusRaddi +

APOCYN ACEAE

Alyxia olioaejormis Gaud. +CASUARIN ACEAE

*Casuarina equisetijolia 1. +COMPOSITAE

*Pluchea odorata (1. ) Casso +*V ernonia cinerea (1.) Less +EBENACEAE

Diospyros [errea var.pub escent Fosb. + +

400 PACIFIC SCIENCE, Vol. 24, July 1970

APPENDIX ( colllil/ued)

SAMPLING SIT ES WITH ALTITUDES

Pre- Pre-historic historic

1955 1840 L 1840 H 1750 L 1750 H Kapoho StainbackSPECIES (930 ft ) (40 ft ) (650 ft ) (300 ft) (990 ft ) (90 ft ) (300 ft)

EP ACR IDACEAE

Stypbe lia tam eiameiae(Cham. et Schlecht. )F. Muel!. + + +

ERICACEAE

Va ccinium retictllat11111Smith + +

EUPHORBIACEAE

Aleurites moluccana(1.) W illd. +

A ntidesma ? IJlatyp hyl/1I111Mann +

GOODENIACEAE

Scaevola taccada(G aertn.) Roxb. +

MORACEAE

*Cec1"opia peltata 1. +MYRS IN ACE AE

Ardisia ellipt ira Th unb. +MYRTACEAE

M etrosideros polymorpbaGaud . + + + + + +*Psidium cattleianu mSabine + + +

*P. gtlajava 1. + + +PIPERACEAE

Peperomia sp. + +ROSACEAE

Osteomeles al/thyl/idifo lia(Sm .) Lind!. +*Rubus rosaejolius Sm. +

RU BIACEAE

*Coffea sp. +M Ol'inda citrijol}« 1. +Psycbotria bauraiiensis Gray + +

URTICACEAE

Pipturus sp. + +