Survey of Tree Planting on an East Coast Hill-country Farm

New Zealand Journal of Agriculture, Volume 79, Issue 5, 15 November 1949, Page 465

Survey of Tree Planting on an East Coast Hill-country Farm

AS a result of past injudicious clearing and burning of bush on hill M country, many New Zealand farmers are now threatened with the development on their holdings of considerable areas or unstable, moving land and heavily-flooding streams. This menace can be conmoving dim iicavxiy . - & . . r f '• trolled in part by the planting of trees and the formation or plantations in strategic positions, and such woodlands can also produce muchneeded farm timber and shelter while adding greatly to the amenities and value of the farmlands involved. In the “Journal for April, 1946, a „ account was given by V. P. Boot of protective planting carried out on Puketiti Station, Mr. A. B. W illiams s east coast bill farm In the following article M. Sutherland, Farm Forestry Officer, Department of Agriculture, Wellington, surveys the behaviour of Department of Agriculture, Wellington, surveys the. behaviour of different tree species and. discusses aspects of the formation and growth of the plantations in the light of silvicultural development during 40 years of , tree growing on this station. .

BOTH success and failure are demonstrated in these plantations, but they are of special value in showing how, Sy simple and persistent annual planting, there may be built up throughout the farm a system of double-purpose woodlots which should become of considerable utilitarian value to their owner. Aspect, and Climate This station lies on rolling and broken country in Waipu County, about 3 miles west of Te Puia Springs township. It now covers about 6500 acres of hill grazing under introduced grass, and of this area it is estimated that about 60 acres are still under native forest, chiefly in scattered patches and valleys throughout the holding.

The lowest part of the holding lies 1000 ft. above sea level, with the peak of Puketiti (1733 ft. rising in the centre. The ground lies generally to the east and north, but . plantations have been grown on all aspects and this factor appears to have little influence on tree growth in this, region. The most general winds are from south and west, but comparatively little indication of any harmful influence of strong wind is apparent in the tree growth of the area. The temperature record nearest to this localityat Gisborne —shows a mean monthly maximum of 66.6 degrees F. and an average minimum of 47.4 degrees. The maximum mean monthly temperature is 95.2 degrees and the extreme minimum 32.4. The annual rainfall at Puketiti is high, averaging 82.93 in., with a mean

monthly figure of. 6.91 in. and a maximum monthly rainfall of 10.14 in. The average rainfall for the dry month is 3.18 in. in November. Frost occurrence is negligible in its effect on tree growth and no damage to plantations has been recorded at Puketiti. Soil and Topography * Two main soil types are found on the holding: Most of the higher knobs are of the Matakaoa sandy loam of the brown loam group, with 4 to 6in. of brown sandy loam on dark yellow sandy loam on rotted, compact, yellow loam; on the lower slopes occurs the Mangatu clay loam of secondary podzol series of soft blue mudstone with sandstone bands, or 4in. of dull brown, moderately-compact clay loam on sticky mudstone clay. From general observation plantations would be expected to grow more rapidly on the brown loam areas. The hilly area is much broken by watered valleys or gullies, many of them worn to sub-gullies by temporary stream flow, the margins being covered by unstable mudstone formation prone to mass movement of the surface layer known as “slumping.” This process of land movement on steeply-sloping ground may be described briefly as follows: The original forest growth regulated the absorption of moisture and the soil surface was held in an absorbent but not waterlogged condition, but after the clearing of native vegetation and the burning of the top mat of humus covering, and with the sowing of English grasses and introduction of stock, the

land surface becomes unstable. During heavy rainfall, with the original ground cover gone and bare conditions brought about by constant grazing, the excess water, instead of being soaked up gradually by moss and humus, runs rapidly downhill in many runnels, which join together and cut into the soft soil. Entering the stream at many points, they greatly increase the volume of water carried by the streambed. The stream overflows and the excess water sinks into the adjoining banks, making the soil soft and heavy. The local formation is characterised by a covering of sticky clay soil im-

posed on the mudstone underlay with which it never incorporates, and the moisture, percolating from the surface, collects along the line of this stratum, causing a breakaway of the heavy wet soil. This slides downward of its own weight, piling up at the base of the slope to form a hummocky “toe” where the stream cuts round the foot of a hill. In addition to the slumping movement of the land which is prevalent on this area, the excess water collected in streambeds during the frequent heavy rains causes a physical breaking down and washing away of

the banks, so that the course of any stream is likely to become - altered with a big rainstorm. History of Planting A large proportion of the inland area of the station was originally in forest, with the seaward slopes in fern. Manuka was not common and, curiously, it is reputedly difficult to establish manuka as a planted crop on any of the Puketiti area. The bush on the holding was cleared and burnt and the ground grassed down about the beginning of the century, and the area was stocked first with Lincoln sheep and later with Romney sheep and a few cattle.

I and 4— Eucalyptus sieberiana. 2— Eucalyptus saligna. 3 and s—Eucalyptus5— Eucalyptus reg nans. 6— Eucalyptus gigantea.

KEY TO SPECIES IN PLANTATIONS 7 Robinia pseudacacia. 8 — Willow plantation (Salix fragilis and S. viminalis). Pinus radiata and Cupressus macrocarpa. 10— Cupressus macrocarpa.

II and —Oregon pine and redwood, mixed crop. 12Poplar species trials. Eucalyptus obliqua and Lombardy poplar. ' - 15— Cupressus macrocarpa and Pinus ■ ponderosa.

After the first few years of clearance, and especially after heavy rainfall in 1916-17, the effects of clearing the absorbent'and anchoring tree layer began to be apparent in slips, soil slumping, stream agradation, and cutting of gullies and streambanks. General instability of the upper soil layers occurred in certain areas of slope. The owners then realised that some means must be found to counteract the effects of loss of forest cover and to . hold up the movement of land' in vulnerable areas. In 1902 tree planting had been started in the vicinity of the homestead site and block plantations were established on the slopes of hills. Experience with these projects suggested that, with the erection of physical barriers and groynes, the planting of certain types of trees on unstable areas acted as a brake on the movement of the ground by anchoring the. surface layers at various points.

The usefulness of willow and poplar planting to arrest the movement of soil on unstable areas was noted and the practice was increased until gradually it became the basis on which all subsequent protective planting has been carried out.

The first introduced trees were planted on the holding in 1902 in the home plantation, and plantation formation was carried out annually in the years following until the First World War, the greater part of the early planting being done in 1907. Some block plantations, were formed between 1916 and 1939 in which trials were made of new —conifer, broad-leaved, and eucalyptus species—and also of silvicultural methods and combinations. The technique of tree planting to arrest erosion was continually developed and put into practice as necessity arose in the main watershed, areas where movement threatened. /

Residual bush covers about 60 acres, and about 180 acres have been planted

in utility species of trees in plantation formation; this is about 3 per cent, of the total area of the holding. The area covered by widespread protective planting of broad-leaved trees is impossible to assess, as much of this planted ground is now back to grazing use. However, the majority of the wide valley bottoms now have a protective cover of wide-spaced willows and poplars. Objects and Methods of Planting With the methods of bush clearing by burning in use when this land was taken up it was not possible to select areas of forest for preservation or to protect isolated areas, because clearing fires could not be controlled and frequently spread further than was intended. However, the owners of the

station were governed by an inherent impulse to plant trees, and the replacement of native forest by plantations of exotic species was a routine part of early station management. Tree planting at that period was primarily as shelter for stock and to produce farm timber, but general beautification of the station was also a strong consideration. After the value of these plantings in restraining threatened soil movements was recognised other objects of tree planting became an adjunct to the control of erosion. In parts of the area deep gulches have been formed by flooded stream wash and marginal slipping, and it is necessary to attempt the arrest or control of further destructive action by treatment in each individual case or

by a general system of preventive management. In such work the main objectives are: First, the immediate prevention of sudden increases in the volume of water fed to a streambed, and hence the stabilisation of the streambanks. This is attempted by regulating the rate of movement of water through the loose soil cover by the formation of a good, compact cover of grass, made possible by spelling from grazing, sowing, good pasture-sward management, and later by further subdivision and controlled grazing. In severe instances of stream agradation it may be necessary to give local protection to vulnerable streambanks and to control stream flow direction by the use of such physical means as groynes or tree planting in regions of the streambed; trees planted in the stream are also of some service to slow down the rate of flow within the banks. Second, the local arrest of land movement—flowage and slumping—by the holding of slumping ground around the toes of slopes with widely-spaced trees, mainly willows or poplars. Third, the ultimate consolidation of large areas above and around the fixed toes by the use of closely-spaced trees to form solid plantation blocks containing usually conifer or eucalyptus species. Tree planting at Puketiti is thus intimately bound up with the special conditions arising from the nature of the country, and as a result a routine procedure, has been evolved resulting from the experience of years. Though on each area a different combination of conditions may exist and the > exact procedure suitable for each must be considered, the same principles are observed in any piece of erosion planting.

Existing Plantations The formation of plantations on a variety of sites and under varying conditions has resulted in a valuable series of tree crops demonstrating different species, ages, and silvicultural systems throughout the area. However, though in general species which prove suitable for growing on Puketiti land will probably produce as satisfactory growth on much of the coastal hill lands of Poverty Bay, there are dissimilar combinations of altitude, soil, and aspect which must be taken into account when, estimating probable production from other new areas on this coast. All early planting entailed experimenting with species and, though definite indications of growth and suitability of several species can now be observed, a great deal remains to be learnt from this area about methods of establishment (such as spacing and mixtures of species) and the management of plantations of introduced species, both evergreen and deciduous. For purposes of description the tree crops may be best classified as pure plantations of one species and plantations of silvicultural mixtures of species. The species which occur on the area in sufficient quantity for judgment are listed as follows: — Occurring as Pure Crops Conifers: Pinus radiata (insignis pine or Monterey pine), Pseudotsuga taxifolia (Oregon pine), Cupressus macrocarpa (Monterey cypress or macrocarpa) , Sequoia sempervirens (Californian redwood), and Chamaecyparis lawsoniana (Lawson’s cypress or Port Orford cedar). Broad-leaved species: Poplars (Populus nigra var. fastigiata, P. alba, and P. serotina) , willows (Salix vitellina, S. fragilis, and S', babylonica) , false or

spiny acacia (Robinia pseudacacia), and puriri (Vitex lucens). Eucalypts: Eucalyptus regnans, E. obliqua, E. gigantea, E. sieberiana, and E. saligna. Silvicultural Mixtures Oregon pine with Californian redwood. Oregon pine with eucalyptus species. Cupressus macrocarpa with oak. Cupressus macrocarpa with Pinus ponderosa. Lawson’s, cypress with European larch. Lawson’s cypress with Oregon pine. Lawson’s cypress with Pinus rigida. Lawson’s cypress, Oregon pine, redwood, and native species (karaka, titoki, totara, kohekohe, olearia, and mahoe) with broad-leaved species of oak, some English beech, Australian blackwood (Acacia melanoxylon) , silver birch, and a little elm. Pure Plantations Pinus radiata This species was included in the earliest planting activities in the home plantation as odd trees or groups of trees among the general mixture of species employed. There are now some fine, massive trees of 40 to 50 years of age which are to be milled in the coming year. These old trees are growing chiefly on the upper slopes of ridges on the main brown sandy loam soil type, but growth apparently is equally good on the lower areas of grey-brown silt loam on clay loam. In the younger plantations, formed on unstable mudstone slopes such as those in the Five River watershed area and Te Wake plantation, where the

trees were spaced widely and in irregular formation, height growth is lower and rate of girth increase greater. To assess timber production on these soil types it would be necessary to make a complete statistical analysis of standing crops throughout all the plantations of this species.

P. radiata was not planted pure to any extent in the earlier operations, but was used as an edge strip on the exposed border of the old plantation planted in 1903.

Before 1912 a big area in Rakautautuni paddock, comprising the basin formed from the junction of five streams, began to give much trouble with flooding of the streams and “toe slumping” of the streambanks. After initial fixation with willows and poplars, the vulnerable areas were planted with P. radiata strips around blocks of Cupressus macrocarpa. This partly arrested the main ground movements, but after 10 to 15 years, when the C. macrocarpa had reached an average height of 35ft., most of them were carried away in a flood resulting from an exceptionally-heavy rainfall of 4 to z 6in. in 10 days. The whole area was then replanted in P. radiata alone, and after about 20 years the area appears to be stabilised along 4 out of the 5 streams. The difficulty in the remaining streambed lies in the lower reaches, and it will require to be tackled by a combination of mechanical protection and special streambank planting.

The trees of P. radiata growing on Puketiti are of good timber-production type, with fairly-light side branches and regular boles. No excessivelylarge cones were observed, the average size being 4 to sin., which is considered a good silvicultural type of cone. Unfortunately, no record exists of the origin of the seed from which the crops were produced, as most of the planting has been done throughout the years with bought-in commercial tree stocks.

On the whole, P. radiata in regular plantation has been planted too closely, the usual distance being about 6ft. x 6ft. in the early operations. This is shown in the belt planted along the northern border of a bush area in the nursery paddock where P. radiata at 6ft. spacing has made rapid growth and provided effective high shelter for the bush from the dry, cold winds, but has selected itself naturally with a wastage of killed-out stems amounting to about 40 per cent., and a consequent irregular crop. In 1928 P. radiata was planted from 8 to 10ft. apart as a northern border to the block of Eucalyptus sieberiana, and after 20 years these pines form an even stocking on the ground, though somewhat heavy branching would appear to indicate rather too wide spacing for best timber production.

P. radiata establishes readily from good 1-year seedlings, 12 to 15in. high, planted in autumn or late winter. This species is now regenerating freely both on grassed hills and within the older plantations of mixed evergreen and deciduous trees. This propensity to seed and regenerate is useful on ground where slips occur and provides a means of obtaining easy tree growth on unstable back areas of the station, but there is a possibility, that in time this pine may become a “weed” species on these hills, especially as Mr. Williams has used it as protective belts

around certain surviving bush areas and these belts may act as centres of seed dispersal.

In the light of the satisfactory growth shown by certain other species planted at Puketiti and the silvicultural disadvantages of P. radiata, it would appear that this is not the best timber tree to use on this land where other species such as Oregon pine or Lawson’s cypress of good quality can be grown. Confirmation of this view must await an area return in terms of timber utilisation and financial return, which will be obtained from the projected milling of the older timber crops to be carried out in the near future.

Cupressus macrocarpa In the earliest plantings Cupressus macrocarpa was used either as marginal belts, only 2 or 3 trees wide, or in mixtures of species, and in general this has resulted in the formation of heavy-crowned, wide-branching trees. Even old trees which can be spared from the shelter belts are difficult to utilise, as they form the outer break, and when grown in mixtures where they have spread and suppressed the surrounding crop their removal would be difficult without damage to neighbouring good trees. These plantings demonstrate the mistake of planting C. macrocarpa in mixtures of trees which will not compete with it and thus produce a heavilybranched, unsuitable type of cypress tree. A certain number of posts can be procured from the branches, but

usually there is a basal length of stem which requires too much labour to split and is often left as waste timber. On Puketiti C. macrocarpa has been grown also in close plantation formation in 2 plantations and growth can now be compared under different spacmg conditions A block in the lower section of the sheepyard plantation was planted m 1928 with pure C. macro™rpa spaced at 6 to 7ft., and this now shows a crop with good height growth, up to 50ft. but uneven and low diameter growth—probably the result of too close planting. This may be compared with the growth on an adjacent block in which the cypress was planted in 1928 at an average spacing of 5 to 6ft. but in a mixture in which a proportion of trees (possibly 30 per cent.) were Pinus ponderosa. . Growth of this species is slow and in the young state crown form is compact, so that the effect produced for the C. macrocarpa was one of wide spacing with excessiye lateral branching partially controlled by the pine stems. The result was that the C. macrocarpa formed a crop of trees of more even growth than that in which close competition induced natural selection and uneven production. The P. ponderosa in this mixture may form a satisfactory permanent timber crop, on a rotation of possibly 50 to 60 years, while the cypress should furnish 2 classes of timber —smaller stems for fencing strainers and posts in the round or split, and mature sawn timber'at 40 to 50 years of age for building construction.

Oregon Pine

This species was planted in the early trials. In 1903 the old plantation was formed mainly of Oregon pine, with P. radiata planted along the margins except, where a' block of Robinia pseudacacia was established in 1907. In the decade following the planting the Oregon pine showed a high percentage of failures, but no apparent cause was recorded. (In the light of planting experience since that time it can be surmised that the failures were caused by a dry season following late planting.) Failures were blanked up with Eucalyptus acervilla on the theory that the eucalypts would catch up with the conifer growth, but though it has kept up in height growth the eucalypt crop has been crowded by the expansion of crown growth of the conifer crop, which probably was planted at a close spacing of 6 or 7ft. and has selected itself naturally.

That indicates the need for a wider spacing for Oregon pine on this land and provides an interesting comparison with the growth of another young block. This block was planted in pure Oregon pine at 9 to 10ft. spacing on an easterly slope of brown loam formation. It had no failures and is now 5 to 10 years old and showing good, even growth with an average total height of . 14ft. and an average breast height diameter of 3 to 4in. The low average height would indicate that this spacing is too wide, but it is too early

to base an opinion on this 1 plantation, especially in view of the similar growth form— height and large diameter . growth—shown by trees of this species elsewhere on the area. Regeneration from , seed cast by the older trees scattered through the mixed plantations around the house is good and would indicate the suit Provided 0 the^Pd 2 n cll m e - aea - umu seed shows a sufficientlycentaeethesZern™ • P ? r " high lltiSde would g hp fairly “ SSpp Af n™^ d - b suitable as a source of Oregon pine seed.

Redwood The oldest redwood trees were planted in groups in the home plantation in 1908, and though these trees now dominate the rest of the species the groups cannot correctly be termed pure blocks, as in early life the? competed with the mixture of broadleaved nd co nifer species planted among them. Measurements of the 13.1^62!l 3 . 1^62 ! tree pf these groups showed a dlam at breast height of 35in. and an estimated total height of 104 ft. in 40 years. Two plantations which were

i + ■ planted as a mixture of redwood and Oregon pine have become almost pure cr ops ,of redwood, and details of these • J 56 given . under the heading of Sf 1 redwood S ’hS hApJSX^ n l ati ° ns holding d h ebe formed ° n the ? S „ Lawson s Cypress This species was planted in the same way as redwood as small groups in a mixture of conifers and broad-leaved ees .> and a small area in the home Plantation now demonstrates its possibllities if grown as a pure crop. This

area was planted m 1913 as a mixture of Pinus rigida (pitch pine) and Lawson’s .cypress, but the pine died out when fairly young and was replaced, where an appreciable space was left, with Oregon pine. In places the Lawson’s cypress have been left unblanked and now form a widely-spaced pure group of well-grown trees of estimated average height of 60ft. and 8 to 9in. diameter at breast height. . These trees indicate that conditions of soil and climate on this area . furnish suitable silvicultural conditions for the growth of this species. The quality of the timber produced now requires to be tested. * * * The only broad-leaved tree crops planted in pure plantation on the area are of willow or poplar—both these being grown for land stabilisation rather than for the formation of woodland—and a very small number of acacias and Robinia pseudacacia. Willows One of the earliest pure plantations was that formed about 1905 on the Puanki track, where at the head of the gully on shale-clay soil land was slipping badly just below the crest; this was fenced and 4 or 5 acres were planted fairly closely (12 to 15ft.) with willow (Salix fragilis and S. vitellina).

This area is now well fixed and carries a crop of trees providing an almost qniiH rrnwn nanonvtrees of j?reat use in land control but of little utilisation value con - 1 but °* bttle - utilisation WiXlvsnaead willows have been Widely-spaced .willows nave been planted on much of the area, using S. vitellvna alone, a mixture of S. vztelhna andS. fragihs, and to some extent - ?hnu+ b^nft nn Snd "liable S fo C move about 30ft. on land liable to move merit. . • . . An experiment was carried out on the Te Wake area using cuttings of hA h to stock though there is no evidenceStonrove this These have formed a good covering of lower •nnn?p Growth (about 10ft) and this S, mav be useful as a holding nVant whSrl a low height is preferred plant where a low heigfit is preierre . On this holding use is made of pollarded willow, in which the lower stem is branchless but a greater proportion of crown is formed. Whether this has any advantage in later growth is questionable, but if successfully Planted these “pollards” with about 6 to. Bft. out of the ground form trees in a short time, able to produce anchoring roots. Stock cannot reach the top. shoots of pollards.; Poplars Poplars in mixture have been used XHnFpiluYis^^P^t^rvar 8 SttioSta and P alba being the%pecies Sfnfed a The ’ sucS freely and in certain areas has now formed pure woodland. na s now . Nine years ago it became desirable to plant over the head of a wide gully running north and south, with spe-cially-good soil, to stabilise the ground, and "opportunity was taken to make a trial of several species of imported poplars obtained from the State For- ■ est Service nursery at Rotorua and. which are being systematically tried out in various parts of New Zealand, The illustration on this page shows their general growth in 9 years compared with. Oregon pine on the same

site. P. robusta, is one which is making good growth. • ' ' , . Robinia pseudacacia a narrow strip of this species planted in 1907 at an elevation of about 1200 ft gives an indication of the possible g r Q Wtb at this high altitude. This c _ o _ now produces durable farm timsuitable for posts, but growth is slower at this elevation than that of a crop on similar soil at a lower altide south of Te Puia. - ernn on Puketiti is of + J he P( noo? stemmed type with only short lengths of straight stem, but if this species were planted in suitable gully land and at regular spacing, a freer growth and therefore a better, stem form might be obtained. Trials of the “shipmast” form are being made at Pu ketiti from root cuttings, wbicb sbow rapid , growth but are too young to provide any information. Purin Two small groups of puriri planted as a pure crop indicate that sufficient growth can be made to provide posts i ze timber m about 30 years. Trees planted between 1915 and 1920 in a group near the house have now Cached a total height of 30 to 40ft. with an average diameter of 14.7 m. above S round level and in this "group were widely SpaCed ’ and is h est i l s? t ‘ ed th? nj f cleS wer A e n at about Bft. spacing clean po n lhsSf more lengths of *2oit. and more. * .*...* Useful samples of several* Eucalyptus species, either in pure blocks. or in mixtures; of eucalypts are growing on the Putiki area, and those showing most silvicultural promise are E. regnans, E. obliqua, E. gigantea, E. sieberiana, and E. saUgna. Other species grown include E. mminahs, which has formed rather poor, badly-shaped, and branchy trees with brittle limbs; prob-,. ably they originated from stock grown from seed collected from a poor-type and unsuitable Australian locality. E.

corynocalyx, which is represented by a few trees scattered in mixed plantations, has formed trees .usually of poor shape with boles inclined to lean from th / perpendicular, but few specimens of good, straight .growth have been obtained and one is under trial as a telephone pole; short lengths have been used for posts, and the indications are that this species would be worth growing here for post timber, Plantations of eucalypt species were formed in some cases by direct seedmg and in others by planting out from bush nurse Eucalyptus regnans A block o this species was formed in 1917 by cultivating narrow strips of grO und 20ft. apart in which the seed was sown as in a nursery seed-bed.. During the first year the seedlings were wrenched, and in 12 months they were thinned out by the removal of the superfluous plants and immediately transplanted into 2 lines between each strip, giving a spacing of about 6ft. This has produced a good, regular stand o clean, tall trees with stem diameters at breast height up to 13.3 in. t 30 vears o f age . The trees of this crop are noticeable . .. at tlipv parrv erev fibrous bark “ ‘the “owVwhile £? typical recmans the upper bark peels off, leaving white, shining stems; this may indicate a special strain in the species high! !n°which this ’species ally flourishes in New Zealand. Mr. Williams is of opinion that this species producing a useful . class of saw timber, but technical tests are required to the coast Sr ° WmS is species on the east coast. . ans was A pure block of E. remans was planted m Te. Wake plantation.in 1924 and appears to be grow S h equal to that of the older crop m t . sheepyardplantation.On the margin of this area P-radiata, wh lcb planted, to fix the unstable s e banks, has also . been interplanted m the eucalypt Mock and though the eucalypts still maintain height domi ancy the pines are crowding them a

must be felled within the next 5 years or so or they may compete with the eucalyptus crowns and reduce the general growth rate. Eucalyptus gigantea This eucalypt was planted in a pure stand in the sheepyard plantation in 1917 by the same strip method as used for E. regnans. It, has made heavy timber growth with good height. Eucalyptus obliqua On an area where deciduous trees had been planted and failed Eucalyptus obliqua was sown in 1909. The seed was sown in strips and seedlings transplanted on the spot, and this plantation now carries a crop of trees with clean, straight 'stems, having made the highest volume. increment of all eucalypt species on the area. The space between stems is now about 12ft., and with the spreading crown development of this species this crop requires a light selective thinning, which would leave a widely-spaced final crop to mature in possibly another 20 years. The timber of E. obliqua is reputedly of good quality for large-dimension sawn boards or scantling, and a trial of this 40-year-grown timber should be made to establish its degree of maturity on this site. Tests for. durability would furnish useful information, as trials in some parts of New Zealand indicate that mature timber of E. obliqua may furnish post timber durable up to 15 years.

On Puketiti this timber has been split fairly easily and is in use as rails and battens on station fences, but it has not been in use long enough to supply evidence of its durability.

Eucalyptus saligna A crop planted 24 years ago on a southerly slope in the northern area of Te Wake plantation has made only fair growth. The height growth is low for this species at . this age and the tree form is poor, stems being unduly branched and not of the clean, straight type characteristic of this species when growing under suitable conditions. A few trees growing in mixture with broad-leaved trees in the home plantation on brown loam soil are of good height and form growth. In Te Wake plantation the poor growth is probably a result of too high an altitude, an exposed southerly aspect, and a shallow, clay-mudstone soil; this species prefers a deep silt or loam soil. Eucalyptus sieberiana Apparently well suited to the conditions at Puketiti, Eucalyptus sieberiana is one of the most silviculturally - promising species which has been tried.

In Te Wake plantation this species was planted 24 years ago on moving land of mudstone . clay loam soil at about 9ft. spacing. It has now produced a tree crop of good height and uneven diameter growth up to about 18in.

An older block on the main roadway, planted 32 years ago, indicates the possible growth of this species. It was planted on a north-west slope on clay loam of the brown loam group at a spacing of 5 to 6ft. Growth has been excellent and, though the stocking is rather uneven, a full crop has been produced, now spaced at 10ft.,

with an average total height of 137 ft. and an average diameter of 18in. One big tree which was measured had a total height of 166 ft. and a diameter of 24.3 in. No timber has been cut and tested at Puketiti, but it is possible that this species may be usable for poles if impregnated Tests of its durability elsewhere have been made only recently and give no final results. Prolific regeneration of this species, about 5 years old, has established itself on a thin soil cover on a rocky northerly face, which indicates a probable ease of establishment. Other Fucalvnts . „ , , , • - Other species of eucalyptus making satisfactory growth on this area are E. botryoides, E. acervilla (ovata), and E. globulus. A species deemed unsuccessful on this station is E hemzphloia, which made only straggling growth and was cut out. . i. lki . , . Silvicultural Mixtures of Species „ , Oregon Pine and Californian Redwood la 1922 a block of land with a northeasterly aspect on a slope of 45 degrees was planted in Oregon pine and redwood spaced at 7 to Bft. with trees of alternating species in each line. The surviving marginal, trees are now chiefly Oregon pine, but throughout the plantation the greatest number of thriving trees are redwoods. The crop ‘ has not been thinned and has selected itself naturally in the ratios of 1 Oregon pine survived to 6 suppressed and 9 redwoods survived to 1 suppressed. In the total crop the average stocking of live trees is now 55 per cent, red- - wood and 45 per cent. Oregon pine, but most of the pines are suppressed and dying trees while the redwoods are growing vigorously, an average tree measured having a total height of 64ft. and diameter at breast height of 14 -3 in In general, these 2 species have the same requirements of soil, aspect, and

climate, but early growth of Oregon pine is usually more rapid. In this case, evidently, optimum conditions have been provided for the redwood, which has overtaken the Oregon pine, which being more light demanding has' gradually become suppressed as the height and lateral growth of redwood have overtopped its stems, shutting off light. ■ This block has also shown that this spacing of 7ft. by 7 or Bft. between lines is too close for both species on this site. Spaced much more widely this mixture might be successful on this area, but the general conclusion is that both species should rather be grown in pure plantations. - . . , x - Oregon Pine with Eucalyptus Species i n the old plantation a block of Oregon pine was planted at 9ft. with the object of making this the permanent crop, but with the aim of obtaining early, clean timber fast-growing eucalypts were planted between the pines, It was planned to remove these after some years when they were no longer required to clean the conifers, but after about 30 years the eucalypts have made such heavy growth that it is now found impossible to remove the trees without risk of damage to the stillimmature Oregon pines. It is concluded from this trial that though the theory was correct it failed in practice in this mixture for several reasons. In this instance the excep-tionally-suitable local conditions for the growth of eucalypt species produced unforeseen and excessive growth of the secondary crop and these eucalypts were left too long in the mixture. It would have been better to have sacrificed the trees by cutting them out when crowding first began, but removal became increasingly difficult, accentuated by the excess-ively-close original planting of the crop (4Jft.). ’ Such a mixture might be successful with much wider spacing— 12ft. between the Oregon pines with inter-

spersed eucalypts— if the eucalypt species used were one which had a slightly-slower height growth rate than that of the pines and were one which could be utilised and removed gradually in the first 20 years. However, with the rate of growth of Oregon pine shown on this holding it is thought that pure crops planted at suitable spacing would be preferable, „ t ■ , Cupressus macrocarpa with Broad-leaved Species or Conifers , Groups of various mixed species with Cupressus macrocarpa are scattered through the older plantations. In most cases the mixture has been formed by the blanking up of failures rather than „„ nl arm pH crons j p • x • xv. v var^nlanStfon^f^unress^s 6 macro" Sroa plantation of Cupressus macro 6ft P snac?ne £ not satisfactory It fav o?rs Fhe ??owth of satisfactory. It fav Yantai it while the nine teJdl to be overshadowed and retarded s ecl a d e de . „ In another group the mixture was Eucalyptus botryoides, Cupressus macrocarpa, and Pinus ponderosa. The resulting crop after 20 years has become a struggle between the eucalyptus, which is now generally dominant, and -the cypress, which has asserted ltself In uneven groups. A mixture of Cupressus macrocarpa with oak spaced irregularly but at an average distance of 8 to 10ft. appears to give promise as a satisfactory mixture on this area. The growth rate of oak is good where it is not exposed, and in this combination it may provide the necessary secondary cleaning crop to produce clean macrocarpa timher without being itself suppressed by the cypress, while the broad-leaved trees add appreciably to humus formation in the soil. Lawson’s. Cypress with Other Conifer Species The oldest Lawson’s cypress group has developed partially into a widely-

spacednow 20ft. or more—mixture of Lawson’s cypress with European larch; this probably was the original mixture. Many larch have died out, but the remainder have made good growth and this now forms one of the most satisfactory mixtures on the holding. The cypress has made good height growth of about 60ft., with a good, straight bole, now partially cleaned up, and appears to be still adding to its diameter. One tree which had been down for about 4 years appeared to have perfectlysound timber, and this will be sawn up for trial.

In 1913 Lawson’s, cypress was planted in mixture with Pinus rigida, but the pine failed to establish itself when the cypress crop was over 10 years old and it was interplanted with Oregon pine. This mixture so far has formed a good combination,, and the Lawson’s cypress has put : on, unusually-good . height growth, but the '2 ’ species are now competing for light and space and probably the mixture has been successful here only because the Lawson’s cypress had 10 years’ start and thus could hold

its own in competition with the Oregon pine. Key to Management Much of the planting at Puketiti which is now producing good specimens of various timber trees has been formed by the unsystematic establishment of a general mixture of species of broad-leaved trees, including native species, and conifers. These areas have received no thinning and show the results of competitive survival. In that respect they form a key to the most suitable trees for the locality, but the rate of growth of the best specimens cannot be taken as a criterion of their possible growth under plantation conditions. On such areas the mixture of conifer and broad-leaved species has produced in its 40 years of growth a thickness of 2 to 3in. of true humus cover, which is now forming a forest soil in which regeneration of both introduced and native species is prolific.

This holding thus demonstrates the possibility of re-establishing tree growth on vulnerable areas of this east coast country. It shows also the first steps necessary in employing tree planting as a routine item in station management for the immediate stabilisation and rehabilitation of slopes which are of more value under forest than when cleared for pasture and forming a potential focus for extensive erosion.

Timber Use The tree crops now growing on Puketiti station collectively provide a valuable demonstration of the possibilities of growing many tree species, both exotic and native, under the conditions on that area. Plantations there show results from both good and bad silvicultural methods of growing trees, and samples are now available showing the growth of nearly 40 species of timber trees of ages between 20 and

40 years. However, little information is available about the quality of the timbers grown, and the owner has been more concerned with the possibilities and methods of growing the trees than with the utilisation of the timbers produced. . These plantations contain material which could furnish a vast amount of muchneeded information about the growing and the utilisation value of many of the species now grown in New Zealand. Much information of this nature is available also from similar areas of trial plantings .throughout the Dominion, and these at present form the important sources of knowledge on which to base any judgment of the behaviour of introduced species under New Zealand’s varied climatic conditions, and especially of the potentialities of many eucalyptus timber species. To be of most value all such information should be collected on an agreed systematic basis so that it can be analysed and correlated at a central clearing station, such as the State Forest Service experimental station. Such a Dominion survey,

based on material now approaching maturity, would provide a knowledge of the quality and uses of available introduced timbers which is required urgently in this period of general timber shortage. The rather random trials made to date at Puketiti give the following indications of timber use values: — Cupressus macrocarpa: Strainers and posts cut from 40-year-old trees and air seasoned have given a life of 14 years and are still sound in the ground. Mr. Williams prefers to use timber from clean trees grown in close plantation rather than material split from rough, branchy, basal logs. Pinus radiata, split for battens and preserved, has been used extensively on the station and shows an effective life of 14 years. Two types of preservation have been used —soaking the battens for a month in spent arsenical sheepdip, or immersing them in a mixture of equal parts of coal tar and used motor oil, boiling them for 1 to 2 hours, then draining them. The

latter method has been used mainly for old and already air-seasoned battens, and the opinion is expressed that with the use of oil alone these hardened battens will not hold staples.

Oregon pine: Suppressed trees removed as thinnings and air seasoned are used for rails and are sound after 15 to 20 years. Small trees split into halves make excellent battens, apparently of exceptionally-long life. Robinia pseudacacia: Timbers cut from trees 20 to 30 years old . are used in the round as posts for fencing and in construction of stockyards. They show no deterioration .in at least 10 years.

Puriri strainers cut from bush timber on the station. and in use for 25 to 30 years show surface shrinkage but sound heart condition above and below ground. Indications are given that posts cut from trees grown for 20 to 25 years on the area probably will prove. suitable for lasting use. Lawson’s cypress: 2in. x lin. timber cut from probably the upper portion of a tree about 20 years old which fell in the plantation was used in a station gate after air seasoning for an unknown period, and it has remained sound for 9 years with 1 coat of paint.

Willow, split for battens, is soaked in spent dip and used extensively in farm fencing. No differentiation is made between the species of Salix. Eucalyptus acervilla (ovata) : Timber split from 20- to 30-year-old trees and air seasoned is used for gate posts. They give promise of being durable, but have not been tested for a definite period. Air seasoned, the timber is used for battens.

Eucalyptus obliqua: Battens and rails split from 40-year-old trees are being tested on fences. Rails in the round have been used in stockyard construction.

Eucalyptus corynocalyx: Scattered trees have been “ felled for trial. The timber is extremely hard and appears to be durable when used as posts without preservative treatment, and these trees are considered to give the best post, timber of all the eucalyptus species grown so far. It may be a promising species for this purpose under Puketiti conditions' if grown in close formation. The growth reached in about 30 years gives suitable dimensions for small pole timber, and a trial of. this as a farm telephone pole has been put in hand. Planting Methods

Measures to combat land movement include 3 phases: First, fencing an area against stock and thus spelling it from grazing for several years while trees are established: that enables the land to become stable, and on a large holding the loss of use of the land is not as important as stabilisation. Second, the establishment of widely-spaced planting as a preventive measure, to fix and stop the land movement, or to hold the fixed area. Third, the formation of closely-planted areas to hold and stabilise the moving land; apparently this is of permanent effect when the correct species are used. For widely-spaced planting poplars are preferable to willows, as they last longer and retain their regular shape, while the willows form heavy, branching tops, which die off much sooner and fall, leaving dead, troublesome snags on the land, which must be replanted. Probably more general use

of osier willow (Salix vitellina) would produce a more uniform low cover, and when the area was opened to grazing its propensity to spread indiscriminately would be controlled by stock. The trial of S. purpurea (Chinese willow) is promising, and though stock do not appear to touch it it is apparently slow in spreading. In the formation of plantations the method used at Puketiti, where ground could be ploughed, of sowing tree seed in strip nurseries and using this area temporarily to produce tree stocks, part of which are left as the permanent crop, is suited to the type of planting which should be more widely practised on east coast high country. There planting operations must be undertaken as other station work allows, and with such a method the farmer does not depend on bought-in nursery stock with its delay in delivery and the danger ~ of deterioration between the time the trees are taken from the nursery and the time when they are replanted. . In the remoter areas some local system of co-operative raising of planting stock by farmer groups might be evolved. Acclimatised stock would then be available without excessive transport delays. Mixed and Pure Crops In the choice of the type of planting most suitable for the hill country these facts emerge:— Mixed crops, if they include broadleaved species, are of more value in forest soil formation and to provide conditions for natural regeneration of tree species. Mixtures of conifer crops have not proved satisfactory except in the case of Lawson’s cypress and larch. The Cupressus macrocarpaPinus ponderosa combination indicates that a similar mixture at suitable spacing may produce a better macrocarpa crop.

Pure crops of 1 species with the rapid rates of growth produced under Puketiti conditions are more suitable for timber production. Mixtures formed by group planting have given good timber production, but are difficult to work . in utilisation operations. ■ More information is required about the most suitable spacing in plantations for the main species. Wider spacing is indicated than has been general at —probably 7 to 10ft., according to species. Successful Species The following species are established as successful on this area: Oregon pine, redwood, Cupressus macrocarpa, Pinus radiata, Lawson’s cypress, totara, puriri, Robinia pseudacacia, Eucalyptus regnans, Eucalyptus obliqua, Eucalyptus gigantea, Eucalyptus corynocalyx, Eucalyptus sieberiana, and Acacia melanoxylon. Species of doubtful growth value are Eucalyptus viminaUs,. . Eucalyptus saligna, and Pinus ponderosa. ' Species unsuccessful are Eucalyptus hemiphloia and Pinus rigida. Local production of farm timber supplies will be necessary on the east coast and has been shown to be possible, but more knowledge is required of the utilisation value of species now being grown and further trials of other likely species are necessary. So far little guidance is available as to the best management of formed plantations for utilisation for farm purposes, and a survey and technical timberuse test would be of great value to farmers in the next decade. In this period also information may be available to -enable an assessment of the financial returns of timber growing in com- : bination with hill-country farming.

A SLEEPING FLOOR MADE OF PRE-CAST BLOCKS