CARNAHAN: INDIGENOUS AND INTRODUCED PLANTS IN THE MANAWATU 15

ECOLOGICAL INTERACTION BETWEEN INTRODUCED AND

INDIGENOUS PLANT SPECIES IN THE

MANAWATU DISTRICT

J. A. CARNAHAN

Divisiol1 of Plant Industrv, C.S.I.R.O.,

Canberra*

INTRODUCTION

As a result of the invasion of New Zealandby people of European origin, and by theplants and animals that they introduced,much of the plant covering of the countrynow consists of mixtures of native and exoticspecies. Smith (1957) has stated that thestudy of this mixed vegetation, while most o[the steps in the amalgamation processes arestill discernible and interpretable, is one ofthe most fascinating and most urgent tasksof New Zealand botanists. However, only afew workers appear to have given special at-tention to the subject, although the contribu-tions of those few, notably Levy (1923),Guthrie-Smith (1926), Cockayne et al.( 1932),and Allan (1936), are of the greatest impor-tance. In the hope of supplementing theexisting contributions, the writer has madean ecological survey of the vegetation of theManawatu district, with emphasis on theinteraction of introduced and indigenousspecies. The results are embodied in anunpublished thesis (Carnahan 1957), onwhich the present paper is based.

THE STUDY AREA

The study area covered about 600 squaremiles on the portion of the catchment of theManawatu River that lies to the west of thecrest of the Tararua-Ruahine Range. To per-mit more intensive study of the main area,certain specialised habitats were excluded.These were the coastal sands and swamps,and the region above timberline (4000 ft.).The south-west part of the area lies belowabout 200 ft., and is more or less flat. The

... This work was done when the author was at MasseyAgricultural College. University of New Zealand.

land rises to the north and east from thisplain, and in general becomes steeper andmore broken with increasing altitude.

Mean monthly air temperatures at theGrasslands climatological station (100 ft.)range from 46° F. in July to 62" F. in January.Rainfall is spread fairly evenly through theyear, and tends to increase with altitude, andwith nearness to the Tararua-Ruahine Range.Mean annual rainfalls at the official rainfallstations range from 35 in. to over 100 in., andmean numbers of days with rain from 120 toover 200.

The alluvial deposits of the plains pro-vide the parent matcrial for a variety o[recent soils. The Pleistocene and Upper Plio-cene sediments of the downs and the lowerhills have given rise to zonal yellow-greyearths and yellow-brown earths, or to skele-tal yellow-brown earths on the steeper hill-sides. Sk'eletal yellow-brown earths are alsoassociated with the greywacke of the higherhills up to about 3500 ft. Above this altitude,mountain soils are found (New Zealand SoilBureau 1948).

The early European explorers and settlersfound most of the district to be covered withdense mixed evergreen forest (Buick 1903).The composition of the former forest covermay be deduced from forest reserves andforest remnants, such as those described byAllan (1924), Zotov el al. (1938), and Grcen-wood (1949). The principal podocarp wasDacrydiwn cupressinul11, and the principaldicotyledonous trees were Bei/schmiedialawa, Weinmannia racemosa, and Metro-sidcros robusta. There was a great variety ofother trees, and tree-ferns were also impor-tant. In the northern part of the study area,below about 1500 ft., Nothofagus solal1dri

16 CARNAHAN: INDIGENOUS AND INTRODUCED PLANTS IN THE MANAWATU

forest occurred on the crests of ridges andspurs, and also on gravelly faces, while N.fusca was present above about 1500 ft. at thenorthern and southern extremities.

Organised European settlement of the dis-trict began in 1871 (Buick 1903). Withinabout 30 years, most of the land below about2000 ft. had been cleared of the originalforest cover, and sown with English grassesand clovers.

SURVEY OF THE VEGETATION

The present vegetation was classified interms of pastoral farming, which is the pre-dominant kind of land-use. There are tworecognisable cultural boundaries, namely thelimit of cultivation and the limit of grazing,corresponding very roughly with the 500 ft.and 2000 ft. contours respectively. The vege-tation within the limit of cultivation wascharacterised as "ploughable pasture"; thatbetween the limit of cultivation and the limitof grazing as "unploughable pasture"; andthat beyond the limit of grazing as "non-

"pasture.

Since it is possible to attain a relativelyhigh degree of control over the vegetation onland that can be cultivated, it is to beexpected that introduced economic speciesshould predominate in ploughable pasture.Further, it is evident from the work of Cock-ayne et al. (1932) that in general the indigen-ous species may be expected to predominateon unoccupied land. Interaction. betweenintroduced and indigenous species maytherefore be expected to be most intense inunploughable pasture. The form of the sur-vey was influenced by these generalisations.The examination of ploughable pasture andnon-pasture was largely confined to carefulqualitative observations, whereas detailedquantitative studies were made in the caseof unploughable pasture.

These quantitative studies involved estim-ating the frequency and cover of each plantspecies present in unploughable pasture, inrelation to soil type, altitude, slope, orienta-tion, and the intensity of grazing by sheepand by cattle. For sampling purposes, Wlitareas of relatively uniform environmentwere delimited, using an adaptation of themethod of Greenall and Hamilton (1954).Relative grazing intensity was estimated by

means of dung counts, set stocking beingassumed. The estimates of frequency andcover of plant species were obtained mainlyby the use of line transects, but these werereinforced by data from quadrat and pointanalyses. Frequency was estimated as thepercentage of transects or quadrats in whichthe species was represented, and cover asthe percentage of each transect line, or ofeach set of points, that was covered by thefoliage of the species. The assessment of theresults was complicated to some extent bypartial correlations between some of theenvironmental factors. The effects of thesefactors have been separated as far as pos-sible. (Full details of the sampling methodsand of the treatment of the sampling dataare given in the original thesis.)

RESULTS OF THE SURVEY

( See Appendix I)

PLOUGHABLE PASTURE

The ploughable pasture vegetation is typi-cal high-producing sown pasture, withLoIium perenne and Trifolium repens pre-dominating. Indigenous species are virtuallyabsent, with the notable exception of severalspecies of funcus, which are a fairly promi-nent feature of the ploughable pasture ofthe study area. f. polyanthemos appears tobe the principal species, and f. luxurians andf. vaginatus are also common. They areessentially weeds of long-rotation pasture,being much less common where there is analternation of short-rotation pasture andcash crop.

UNPLOUGHABLE PASTURE

Sward-forming species

The dominant species of the sward are allperennials, comprising three introducedgrasses, an introduced herb, and an indigen-ous grass. In terms of frequency and cover,Agrostis tenuis and Anthoxanthum odora-tum are the chief sward-forming species innearly every unit area sampled. Festucarubra var. commutata has a more limiteddistribution, but is liable to be a dominantwhere it does occur. The principal expres-sion of this species appears to be underrelatively heavy sheep grazing and on sandyskeletal soils. Hypochoeris radicata and the

CARNAHAN: INDIGENOUS AND INTRODUCED PLANTS IN THE MAIXAWATli 17

indigenous Danthonia agg. (D. pi/osa-D.semiannularis) rank next to these species interms of cover, but are present in more unitareas than Festuca rubra var. commutata.The principal expression 'of Hypochoerisradicata appears to be on the skeletal soilsderived from greywacke, and at the higheraltitudes. Danthonia agg. appears to favourthe steeper slopes. This taxon is usuallyregarded as tending to be more common onsunny faces, but the analyses made in thepresent work do not reflect this tendency.

The introduced species that rank amongthe chief subordinate species of the swardare all grasses or clovcrs, namely Ho/cuslanatus, Lo/ium perenne, Cynosurus crista-tLlS, Dactylis glomerata, Trifolium repens,and T. dubium. All are widely distributed,but Lolium perenne and Trifolium repenstend to be associated more particularly withrelatively heavy shecp and cattle grazing.Several introduced herbs, namely Saginaprocumbens, Cerastium glomeratum, Linumcatharticum, Bellis perennis, Leontodonl"ysseri, Taraxacum officinale, Plantagolanceolata, and Prunella vulgaris, are alsowidely distributed, but are less commonthan the introduced grasses and clovers. Mostof these introduced subordinate species areperennials. Three introduced species of Cir-sium, namely C. vulgare, C. palustre, and C.arvense, have a scattered distribution overa wide range of habitat. Such importance asthey have is largely seasonal, since the firsttwo are biennials, and the last is a diebackperennial.

The indigenous species that rank amongthe chief subordinate species of the swardcomprise four perennial herbs and twomosses, namely Nertera setulosa, Acaenaagg. (A. anserinifolia-A. novaezelandiae),Hydrocotyle agg. (H. moschata-H. novae-zelandiae), Helichrysum filicaule, Thuidiurnfurfurosum, and Acrocladium auriculatum.In general, all of these species appear to becommon under both heavy and light grazingby sheep and cattle. The first five tend to beassociated more particularly with the skele-tal soils derived from greywacke, and withthe higher altitudes, while Acrocladiurn auri-culaturn has a wider range. Four other in-digenous perennial herbs have a more scat-tcred distribution, but are sometimes oflocal importance. Oreornyrrhis colensoi and

Dichondra repens appear to have much thesame habitat preferences as the more com-mon indigenous herbs, whereas Centella uni-flora tends to be more prominent at loweraltitudes. Nertera granadensis appears tofavour shady faces and to have some associa-tion with the steep slopes between hillsidestock tracks. Two indigenous mosses, Tri-quetella papilIata and Campylopus clavatus,are fairly widespread, but are not verycommon.

Large monocotyledons

The principal species considered underthis heading are three indigenous species offuncus, namely f. polyanthemos, f. vagina-tus, and f. luxurians. The first of these isamong the most important non-sward-forming species. All three are more particu-larly species of lower altitudes, and havesome tendency to be associated with sunnyslopes. Further, all appear to be commonunder both heavy and light grazing. Theyshow no special association with poorlydrained soil. Two other large indigenousmonocotyledons of some importance areCarex lucida and Arundo conspicua. Carexlucida appears to have much the same habi-tat preferences as the species of funcus men-tioned above. Arundo conspicua also tendsto be a species of sunny slopes, but appearsto be associated with relatively light grazing.

Ground ferns

The ground ferns of the unploughable pas-tures are indigenous. An important featureof these species is that they are not merelyof seasonal significance. While they may dieback to some extent during the winter, theiroccupation of any area is essentially con-tinuous.

Pteridium esculentwn and Paesia scabe-yuia are the most common ferns, and alsorank numerically among the most commonnon-sward-forming species. Although bothspecies occur over a wide range of environ-ment, they tend to be associated more par-ticularly with steeper slopes, with the grey-wacke soils, and with relatively light sheepand cattle grazing. Pteridum tends to beslightly more prominent at lower altitudes,and Paesia at higher altitudes, while anotherdistinction is the apparent tendency of Pae-s;a to be associated with shady faces.

18 CARNAHAN: INJ)[GENOUS AND INTRODUCED PLANTS IN THE MANJ\\\lA'rtJ

Next to these species in numerical impor-

tance is Blechnum flu\liatile, which occurs insimilar environments to Paesia scaberulu,but has a stronger association with thehigher altitudes. Several other indigenousspecies of ferns, namely Histio[Jteris incisa.Polystichum~v"stilT.lf1r,' Gyclifsorus 'pennige-

.

rus, Blechnum procerum, and B. discolor,are less common. There is a general tendencyfor these species to be associated with grey-wacke soils, relatively light grazing, higheraltitudes (particularly Polystichum 1'esti-tum), steeper slopes, and shady faces.

Shrubs and small trees

Indigenous species are predominantamong the shrubs and small trees of un-ploughable pasture. The only importantintroduced shrub is Ulex europaeus, whichis often plentiful at lower altitudes, particu-larly on steeper slopes and under relativelylight grazing. Also, the introduced Saratham-.nus scoparius occurs in localised pockets,particularly on north-facing slopes and atlower altitudes.

The most common woody species of un-ploughable pasture, both as a shrub and asa small tree, is Leptospermum scopariun1.This species appears to favour the soilsderived from soft sandstones and mudstones,and is much less prominent on the grey-wacke soils (although it appears to beadvancing actively on to these soils). Thepresence of established plants appears to beassociated with relatively light sheep andcattle grazing. At the time when the fieldwork was carried out, the "manuka blight"disease of Leptospermum scoparium wasnot prominent in the study area, in spite ofrepeated efforts by farmers to spread it.Some establishment has occurred since then,but Leptospermum scoparium appears to besurviving, although checked or killed inplaces (Hamblyn 1959).

Next in numerical importance isCoprosmarhamnoides, which is essentially a shrubbyspecies. It shows much the same habitatpreferences as Leptospermum scoparium,but has a slight tendency to favour steeperslopes and shady faces. Leucopogon fascicu-latus, another largely shrubby species, isoften associated with Coprosma rhamnoides,but is less common.

Brachyglottis repanda and Melicytus rami-

florus are fairly common, both as shrubs andas small trees. They occur more particularlyun ihe soiis derived from greywacke, onsteeper slopes, and under relatively lightsheep and cattle grazin;S, and show a possihletendency to favour shady faces. The lesscommon Geniostoma ligustrifolium occursunder similar conditions. The tree-fernsDicksonia squarrosa and Cyathea medullarisare also fairly prominent under similar con-ditions, particularly at higher altitudes andon shady faces. Two other shrubby speciesof some importance are Muehlenbeckia com-plexa and Metrosideros diffusa, which formcharacteristic low dense cushions in pas-ture. Both species tend to favour grey-wacke soils and higher altitudes. The micro-habitats provided by the steep slopes be-tween hillside stock tracks and by logs andstumps appear to encourage the establish-ment of these two species.

The shrubs Olearia virgata, O. sO/cl1ldri,and Cassinia leptophylla are less common,although Olearia solandri is quite aggressivein at least one valley, and Cassinia lepto-phylla is fairly prominent at the southernextremity of the study area. Olearia -,'irga[(/is found more particularly at higher alti-tudes, and the other two species at loweraltitudes. All three tend to be associatedwith relatively light grazing.

Several other woody species becOlneprominent towards the upper altitudinallimit of pasture. Pseudowintera coloraill ap-pears in pasture at about 1500 ft., and isoften the most common shrub above about1750 ft., particularly on ridge tops. Fuchsiaexcorticata tends to be prominent in similarsituations to Pseudol1Jintera colarata, and toreplace that species in the vicinity o[ water-courses. Finally,' there is copious regenera~tion of Nothofaglls fllsca at about 2000 ft. atthe northern extremity of the study area.

NON-PASTURE

The non-pasture vegdation falls jnto twomajor categories, namely more or less lTIodi-fied forest, and "secondary growth" (Levy1923, Croker 1953), that is, the successionalvegetation that arises after forest has beencleared.

There has been little penetration of intro-duced species beyond the margins of the

CARNAHAN: INDIGENOUS AND iNTRODUCED PLANTS IN THE MANAW.\TU 19

forests, even where these forests have beenmodified considerably. Within the forests, afew herbaceous species, such as Carduustenuiflorus, Cirsium vulgare, Crepis capil-laris, Hypochoeris radicata, Senecio jaco-baea, and Digitalis purpurea, may be foundon slips, or in open places where the originalvegetation has been destroyed by fire orstorm.

If cleared land is abandoned, introducedherbaceous species may be common enoughin the first stage of succession. Ho\,vever.they do not appear to survive the formationof a shrub canopy. The dominant species inthe shrub and small tree stages of the suc-cession include Leptospermum scoparium,Brachyglottis repanda, Melicytus ramiflorus,and Cyathea medullaris. The only intro-duced shrubs of any importance are Ulexeuropaeus and Sarothamnus scoparius. Boththese species are characteristic of the earlierpart of the shrub stage, and tend to becomeovershadowed, and be replaced, by the indi-genous speCIes.

DISCUSSION

PLOUGHABLE PASTURE

The great competitive vigour of Loliumperenne and Trifolium repens, under condi-tions of high fertility, has been recognisedfor a long time (Armstrong 1907), and it iseven more pronounced in the case of modernhigh-producing strains (Levy 1951). Thereseems little doubt that the dominance ofthese two species, in combination with heavygrazing, is largely responsible for the virtualabsence of indigenous species (other thanspecies of Juncus) from plough able pasture.

This conclusion is supported by the factthaLindigenous weeds may be virtuallyabsent from pasture on land that has neverbeen cultivated, provided that Lolium per-enne and Trifolium repens are the dom-inants. Analyses of several such pasturesshowed the presence, as common subordin-ates, of Agrostis tenuis, Anthoxanthum odor-atum, and Holcus lanatus, indicating thatthe pastures were not of particularly highquality. Nevertheless, species other thangrasses and clovers provided little cover,although a few, such as Ranunculus repens,Cerastium glomeratum, and Hypochoerisradicata, were of fairly high frequency. The

only indigenous species recorded wereJuncus polyanthemos and the moss Trique-tella papillata. In view of the fact that eventhe introduced herbs, with a long history asspecies of grazing land, do not appear to bevery common in such pastures, it is notsurprising that the indigenous species arepoorly represented.

Cockayne et al. (1932), while recognisingthe importance of competition in relation tothe virtual absence of indigenous speciesfrom "high class" pastures, have alsoascribed some significance to the usuallyconsiderable distance between such pasturesand any indigenous plant-community. How-ever, the present study has suggested thatindigenous species may be scarce in pasturesthat are actually adjacent to a source ofindigenous species, provided that those pas-tures are dominated by Lolium perenne andTrifolium repens.

The special status of the indigenousspecies of Juncus in plough able pasture maybe due at least in part to the rhizomatoushabit, which is not common in the indigen-ous flora. Merry (1934) has shown that aspecial programme of cultivation is necessaryprior to sowing, if regeneration of Juncusfrom the rhizomes is to be prevented. Fur-ther, the tough, leafless, erect stems of thesespecies do not appear to be affected by tram-pling, and are rarely browsed by stock.

UNPLOUGHABLE PASTURE

The pattern of vegetation is perhaps bestinterpreted in terms of historical origins. Onthis basis, the in troduced species can betreated as one group, while the indigenousspecies can be separated (with some border-line cases) into two groups.

The widespread occurrence of the com-mon introduced sward-forming species isprobably largely related to their presence inthe original imported seeds-mixtures, whiletheir fairly uniform distribution may reflectability to grow under a wide range of en-vironmental conditions. The more restricteddistribution of the introduced shrubs Ulexeuropaeus and Sarothamnus scoparius sug-gests that these species are still spreadingfrom their poin ts of release. Both speciescertainly appear to be advancing in somelocalities.

20 CARNAHAN: INDIGENOUS AND INTRODUCED PLANTS IN THE MANAWATU

Some of the common indigenous speciesof unploughable pasture are common sub-ordinate species in the surviving forestswithin the warm temperate belt (0-2000 ft.).This group includes the following ferns andwoody species: Blechnum fluviatile, B. pro-cerum, B. discolor, Histiopteris incisa,Cyclosorus pennigerus, Dicksonia squarrosa,Cyathea medullaris, Brachyglottis repanda,Melicytus ramiflorus, Geniostoma ligustri-folium, Muehlenbeckia complexa, and Metro-sideros diffusa. (Polys tic hum vestitum,Pseudowintera colorata, and Fuchsia excor-ticata are also common in forests in theupper part of the warm lemperate belt.)Since the natural habitat of these species ischaracterised by reduced light and highhumidity, it is not surprising that in the openthey tend in general to favour the higheraltitudes (which are associated with in-creased cloud and rain), and also the shadvfaces.

--

The other common indigenous speciesform a rather heterogeneous group. Firstly,there are the sward-forming species andlarge monocotyledons, and also Pteridiul11esculentum, Paesia scaberula, Leptospennwnscoparium, and Olearia virgata. These arethe species that appear to have been morecharacteristic of breaks or open places inthe original vegetation. (Although its distri-bution within the study area may be due atleast in part to deliberate spreading (Saxby1956), Danthonia agg. is probably best allo-cated to this group.) To these should beadded Coprosma rhamnoides and Leucopo-gon fasciculatus, which are common forestsubordinates only in the well-lit Nothofagussolandri forests, and also Olearia solandriand Cassinia lep(ophylla, which may havebeen confined originally to the coastal vege-tation. It might be expected that the mem-bers of this group would be better suited tolife in the open than Ihe members of theother indigenous group, and in general theydo show some tendency to occupy a widerrange o[ environment in unploughable pas-ture. In addition, some of them appear totolerate relatively heavy grazing. It is under-standable that this third group should con-tain some species that are generally regardedas major weeds o[ pasture, notably Lepto-spermum scoparium, Pteridium esculentum,Paesia scaberula, the funcus species, andAcaena agg. As Cockayne et al. (1932) have

indicated, the apparent aggressivenes ofthese species is largely due to the creationon a wide scale of habitats suitable for them.

The apparent aggressiveness of the weedspecies, both native and introduced, alsoreflects a lack of competitive vigour on thepart of the introduced grasses and clovers.Because they are barriers to the establish-ment and maintenance of high-producingeconomic species, steep slopes and poor soilsshould probably be regarded as the twofactors that are largely responsible for thepresent floristic composition of un plough-able pasture. The influence of these factorsis now being modified by the development ofthe aerial distribution of herbicides, seeds,and fertilisers. In view of the known effectsof these practices (Matthews 1959, Suckling1959). it is to be expected that there will besome trend towards a kind of vegetationmore like ploughable pasture. However, sucha trend is likely to be limited by the diflicultyof achieving the same intensity and flexi-bility of management as on ploughable land.

Another possible change of some interestconcerns the distribution of certain impor-tant or potentially important shrubby weeds,such as Leptospermwn scoparium, Ulexeuropaeus, and Cassinia leptophylla. Theseare the species that do not appear to havereached their environmental limits, and mavbe ~apablc of spreading considerably beyondtheir present range. On the other hand, theirfurther spread may be cheeked by the im-provement practices referred to above.

NON-PASTURE

Cockayne et al. (1932) have stressed thatthe pattern o[ interaction is influenced bythe relative numbers o[ introduced andindigenous species, and by differences in lifeform and habitat preference. In the non-pasture vegetation of the study area, Ihe pat-tern of in teraction certainly appears to berelated to the scarcity of woody species inthe introduced flora, and also 10 the factthat the available introduced species arclight-demanding rather than shade-tolerant.Succession in -this vegetation is essentiallya process of replacement of introducedspecies by indigenous species. This has beenwell demonstrated in a recent study of simi-lar vegetation by Druce (1957).

CARNAHAN: INDIGENOUS AND INTRODUCED PLANTS IN THE MANAWATU 21

CONCLUSION

It is evident that unploughable pasturcoffers the widest field for further, moredetailed work on interaction. The classicalstudies o[ the effects of management on thiskind of vegetation (Levy 1923, Guthrie-Smith1926) should now be augmented by experi-mental studies of the effects of modern im-provement practices, such as those beingcarried out by Suckling (1959). Apart fromits botanical interest, the information ob-tained through such studies could well be ofconsiderable importance in assisting farmersto make the most effective use of these newpractices.

ACKNOWLEDGEMENTS

I wish to express my thanks to Dr. J. S.Yeates (supervisor), and to Professor V. J.Chapman and Dr. L. H. Millener, for theircriticism of the original thesis; also to Mr.C. W. E. Moore and Mr. A. B. Costin for theircriticism of the present paper.

NOMENCLATURE

The nomenclature used in the text largelyfollows: Allan's "Handbook of the Natural-ized Flora of New Zealand"; Cheeseman's"Manual of the New Zealand Flora" (secondedition) (for the indigenous phanerogams) ;Dobbie's "New Zealand Ferns" (fourth edi-tion); and Sainsbury's "Handbook of theNew Zealand Mosses". Deviations from thefirst two manuals are as follows, the dis-placed name being in brackets. Introducedspecies: Cirsiu11l vulgare (C. lanceolatwn);Leontodol1 leysseri (L. nudicaulis); Saro-thamnus scoparius (Cytisus). Indigenousspecies: Acael1a al1serinifolia (A. sanguisor-bae); Centella ul1iflora (C. asiatica); funcusluxurians (part o[ f. polyanthemos); Metro-sideros diffusa (M. hypericifolia); Nerteragranadensis (N. depressa); Oreomyrrhiscolensoi (0. andicola) ; Pseudowintera color-ata (Dri11lYs).

REFERENCES

ALlAN, H. H., 1924. Forest remnants in the neighbour-hood of Feilding. Rep. 16th Meeting Allstrala!>'ianA.A.S.: 402-404.

ALLAN,H. H., 1936. Indigene versus alien in the NewZealand plant world. Ecology 17: 187-193.

ARMSTRONG,S. F., 1907. The botanical and chemicalcomposition of the herbage of pastures and meadows.J. A!?ric. Sci. 2: 283-304.

BUICK, T. L., 1903. Old Ma1/{Ma/lt. Buick & Young,Palmerston North.

CARNAHAN,1. A., 1957. A study of ecological interactionherw(,(,1l introduced and illdigenolH pla"t species in111e MlI1wwatll district, North Island, New Zealand.Unpub. Ph.D. thesis, in Massey Agric. Coli. library.

COCKAVNE. L., SIMPSON, G. and SCOTI-TIIOMSON, J.,1932. Some New Zealand indigenous~induccd weedsand indigenous-induced modified and mixed plant-communities, J, Linn, Soc. Lond. (Bot.) 49: 13-45.

CROKER. B. H., 1953. Forest reg~neration on the WesternHutt Hills, Wellington. Trons. Roy. Soc. N.Z. 81:] 1-21.

DRUCE,A. P., 1957. Botanical survey of an experimentalcatchment, Taita. New Zealand. Dept. Sci. & [nd.Re.\'. N.Z. Bull. 124.

GREENHALL,A. F. and HAMILTON,D., 1954. Soil con.servation surveys in New Zealand. N.Z. J. Sci. Tech.35A: 505-517.

GREENWOOD, R, M., 1949. Totara reserve. Bull. Welling-ton Bot. Soc. 21: 2-7.

GUTHRIE-SMITH,H., 1926, TUfira, the story of a NewZeahmd ~;heep station, 2nd edn. Wm. Blackwood &Sons, Edinburgh,

HAMBLVN,C. 1., 1959. Manuka blight losing its effective-ness in North Island. N.Z. J. Agric. 99: 119-123.

LEVY,E. B" 1923. The grasslands of New Zealand. Seriesn. The Taranaki back-country. N.Z. J. Agric. 27:138-156,281-293.

LEVY, E. B., 1951. Grasslands of New Zealand. Tech.Corresp. School, N.Z. Educn. Dept.

MATI'HEWS,L. 1., 1959. Use and limitations of chemicalploughing, Proc. 12th N.Z. Weed Control COllf.43-48.

MERRY,D. M. E., 1934, An ecological study of rushes inplulure. Unpub. M.Agr.Sc. thesis, in Masse;' Agric.Coil. library.

NEW ZEALANDSOIL BUREAU, 1948. Soil map of NewZealand (32 mile.'i to tlte inclt).

SAXBY,S. H., 1956. Pasture production in New Zealand.Dept. Agric. N.Z. Bull. 250,

SMITH, C. M., 1957. Changed and changing vegetation.In Science in New Zealand. Ed. F. R. Callaghan.A. H. & A. W. Reed, We1lington.

SUCKLING.F. E. T., 1959. Pasture management trials onunploughable hill country at Te Awa. U. Results for1951-57. N.z. J. Agric. Res. 2: 488-543.

ZOTOV,V. D., 1938. An outline of the vegetation andflora of the Tararua Mountains. Trans. Roy. Soc.N.Z. 68: 259-324.

22 CARNAHAN: INDIGENOUS AND INTRODUCED PLANTS IN TilE MANAWATU

APPENDIX I Ground ferns

SUMMARY OF RESULTS OF SURVEY

(D-dominant, C--common, o-Jess common)

Introduced species Indigenous species

PLOUGHABLE

LoUum perenne D

Trifolium repens D

PASTURE

Pteridium esculentum C

Paesia scaberula C

Blechnum fluviatile C

1fisciopteris incisa 0

Polystichum vestitum 0

Cydosoms pennigerus 0

Blechnum procerum 0

Blechnurn discolor 0

Shrubs and small treesluncus polyanrhemos C

Juneus luxurians 0

Juneus vagina/us 0

Ulex europaesus C

UNPLOUGHABLE PASTURESarothamnus ,~coparius 0

Sward-forming species

Agrostis tenuis D

Anthoxonthum

odoralum D

Festuca rubra

vaT. commutata D

Hypochoeris radieo/a D

Holeus lanG/us C

LoUum perenne C

Cynosurus cristatus C

Dactylis glomera/a C

Trifolium Fepens C

Trifolium dubium C

Sagina- procumbens 0

Cerastium glomeratum 0

Linum catharticwn 0

Bellis perennis 0

Leorrtodon leysseri 0

Taraxacum officinale 0

Plantago lanceolata 0

Prunella vulgaris 0

Cirsium vulgare 0

Cirsium paIustre 0

Cirsium arvense 0

Danthonia agg.

Nertera setu/osa C

A caena agg. C

Hydrocotyle agg. C

Helichrysum filicaule C

T/lllidium fiUcaule C

Acrocladium audculalum C

Oreomyrrhis colensoi 0

Dichondra repens 0

Ccntella uniflora 0

Nertera granadensis 0

Triquetella papillata 0

Campylopus clavatus 0

Leptospermum scoparium C

Coprosma rhamnoides C

Brachyg/ottis repanda C

Melicytus ramiflorus C

Leucopogon fasciculatus 0

Geniostoma ligustrifolium 0

Dicksonia squarrosa 0

Cyathea medullaris 0

.\1uehlenbeckia eomplexa 0

Metrosideros diUusa 0

()learia virgata 0

Olearia solandri 0

Cassinia /eptophyJ/a 0

Pseudowintera colorata 0

Fuchsia exeorticata 0

NOlhofagus fusea 0

NON~PASTURE

Carduus lenuiflorus 0

Cirsium vulgare 0

Crepis capillaris 0

Hypoehoeds radicata 0

Senecio jocobaea 0

Digitalis purpurea 0

Herbs

Shrubs and small trees

Large monocotyledons

Juncus po/yanthemos C

Juncus vaginatus C

Juncus luxurians 0

Carex lucida 0

Arundo conspicu(l 0

U/ex europaeus C

S(lrothomnus scoparius 0

Leptospermum seoparium D

Brachyglottis repanda D

Melicytus ramiflorus D

Cyathea medullaris D