Section 6 Land Resource Inventory. '- . ' ~":, .~ --C'I::,.., --:•,:·__ rny~ ...,....,._,7 ,.., AGltlCUl.l\JREand HOl<TIC\Jll\JRE ~-=~-...nat IZ'3 - CIID- ...,,_.,,,., IOI: IIQIIT'O,UUIII o-,.._.., _____ ---·--· ,.,,,._ s..;1at.i,, I« J>GalCVlMEand HOl<TICIATURE ••i- -----,-- INl);GENOUS FORESTRY Phylicol Suitability Fo, fNDIOENOUSFORfS':, ... PhyKol Swobillry lot EXOTIC FO~ESTRY 0 • thy,icOI Sui1oblit y lo, S::Yt"\TI( s:noi:~ T: '¥' l ·.;, , '1iC:1, . tfCIEATION""'"s..,.- r lat -------------------, '* GREAT BARRIER ISLAND WETLAND HABITATS 8 l<Oiitok.. Sv.-o,.,,p Ond Crull. C Moky ,-c-r-tn Sl,-eo,n 0 Mtd l ond~ Ouch North t!il\li K c~, ~u,.,S\,,,om p L rorcstry 1-tO.&y P J<cicr cro Day Q l<iwir-il<i O<ly R Motoirchc- ao1 S J.lotoirtt:c- $,,,.,.:~ v wo,ruu ~o:, V Wher,;o;>orcporo Hoarb,:n,1r e!)!.E.fillA.L • W Vl)~r ,-.·.~opo,,o ·c.s tuory l OVT$TANOll'fG . Ill KIGH .. OIJT~T~NOINO · .\ .,,,.·,-~rd. I!lill . :· WryWI ~ : -' .. CiU•r"" . •. • 1 I.,· l[J;] , •: /' l"u,.)l.ul ·\'-.~:•:=d r;_: ; . T S;»llc-u Croll• POT£NTIAL 8B ,.. 1-:cw Zcolol'ld Oottel"Cf L~c-•t CO'Kcl'ltf"Ol!o111 of Qrc,,,,,n T~ I. • ,..,.,..,,, lrnportont '••dl"'f 0,._ , S)"l'\bOI'• r«prt,.,....t •;ot •-lhtr11~, c11•• ore lor 8ro...,n TcoL • ploCcd bc-:sf(c the- lld•itot in wn.c.h U'l<I' O· CONSEA\IATION ~ l a.::c.-.·. CONSERVATION land lia~ r(fl 33 SECTION6 LANORESOURCE INVENTORY 6. 1 PURPOSE OF THE STUDY One of the fundamental problems that the Council has faced in the prepara tion of the District Scheme, has been the lac k of suitable research information, to be able to assess the land use alternatives available on the Island . In the past, information was either out of date or uncoordi ~ated, and this added to the difficulity in analysing t he land use capability. The decision was made by the ·council early in preparation of the District Scheme that a land use assessment be made covering the County. This study was coordinated by the Lands and Survey Department, in conjunction with the Council. The intention was that the study be used as a planning tool to assist the Council in making land use management decisions for the District Scheme. ....... •.,i The invo lved Government Agencies were:- I . Lands and Survey Department. 2: New Zealand Forest Service. 3. The Department of Scientific Industrial Research. 4. The Department of A9ricul ture and Fis heries. 5. The Wildlife Division of the Department of Internal Affairs. 6. \'later and Soils Division of the Ministry of Works. 6.1.1 OBJECTIVE: The purpose of the Land Resource Inventory could be summarised as follows:- (a) An inventory of the various natural resources and cultural features of the Islan d. (b) A classification and identification of the various concerns of Central Government Agencies, private interest groups and the Counci 1. (c) An assessment of some of the potential uses of the land resources that Great Barrier Island can sustain. (_d) To guide and aid Central Government Departments Involved with planning land resources on the Island. (e) To guide and aid the Council in the preparation of the District Scheme and its administration. 34 6 . 1.2 RESPONSIBILITYFOR ADMINISTRATION The Land Resource Inventory in tota 1 is not part . of the Council's District Sch.Ellle. However the Council has fonnulated statements from the work covered by the Inventory, and intends these to fonn the basis for future land uses proposed i n certain areas. The Land Resource Inventory identifies the environmentally sensitive areas and in response to these factors, various zones have been derived, pennitting or restricting land use activities. 6. I. 3 GOVERNMEtlTUSES OF THE RESOURCEHlVENTORY Government Agencies have also use d the Land Resource Inventory to help fonnulate po 1ici es for Crown Land. The main areas that this app l ies to are the Lands and Survey Block at Harataonga, and the Hew Zealand Forest Service State Forest in the centre of the Island. 6.2 TOPOGRAPHY The topographic pla n of the inventory is based on plans held by the Lands and Survey Department. The purpose of the Slope Plan is to determine the 1and areas, irrespective of ownership or contro 1s that ca n suggest a 1ter nat i ve forms of land use. The most import ant aspects - ar e the restrtctions of certa i n la nd uses on steep areas , due to water and soi l and conservation constraints. OBJECTIVE:To encourage the use by the gene ral public of the Slope Map to enable suitable land uses or alternatives to be considered • ...- , j POLICIES: 1. That agricultural or horticult ure be encouraged on land having a suitable zoning . 2. To ensure that land is not subjected to clearing or destr uction of vegetat i on where erosion or 1and stability problems are ir.minent . Land clearing and destr uction of vegetation will be discouraged. 6. 3 CLIMATE The rainfall recorded at Port Fitzroy, is between 1500 and 1700mma year, with approximately 75% occu r i ng bet11een the winter months, April to September . This makes for dry periods during the summer, with rainfalls occ"ring on about 160 days annually. Temperatur e ra nges 24°c maximumduring sumner to s0 c minimum during winter. 35 The climate is similar to the districts immediately to the North of Auckland; the climate is warm and humid during the summer, droughts can occur during the period December to Apri 1 . 6.4 SOILS About two fifths of the Island's area (11,200 hectares) · consist of Skel etal soils. This country is steep to very steep, covered mostly in forest and scrub. A further 4,300 hectaresar.e steep and ro lling . These soils are mostly of a clay type and are formed from greywacke, andesite, some daci te and basalt. Volcanic rock and andesite covers mostly steep to rolling country.(11, 445 ha) Erosion is a hazard in these areas, due in some measures to the granular nature of the soil . Under dry conditions there is wind erosion and in rainy periods sheet erosion. This erosion i s mostly a feature of North facing country . In developing this class of land, strict soil conservation measures are needed to preve nt erosion. There are about 1,000 hectares of easy rolling country, part of which are consolidated. sands. Alluvial river flats occupy about 180 hectares, with peaty loams in drained and undratned swamps covering 770 hectares . 6.4. l Table showing soil groups on the Is land . 36 Percent of Total Area Skeletal Soils 11,200 Steep and very steep 53 steep rolling to steep 4,300 Rolling and steep rolling 11,445 40 Easy 1,000 Peaty loams (drained and undra ined swamps) 770 7 Alluvial soils 285 29,000 100 The soils of Great · Barrier ls land have deve 1oped in a warm moist climate under a sub-tropical rain forest. This process has led to soils of low natural fertil ity which tend to be acidic and poorly supplied with many plantnut rients apart from magnesium. Phosphorus and calcium are both deficient . These comments not only apply to soils formed from sedimentary and volcanic rock but also to the soils of valley floors be they alluvial, peaty or the low sandy easy ridges rising from the peaty swamps. Nial bringing any of this land into past ure, superphosphate is needed and lime would also be beneficial. All alluvial and swamp land needs to be drained, using init ia lly an open drainage system to lo..er water tables. As sooe of this land is no great height above sea level, problems arise due to bar formatio n at stream outlets to the sea, or because of the difficulties in deepening channels. 6.5.1 LIVESTOCKTRENDS The following table shows the trends in stock numbers over the past JO years: 37 TABLESHOWING LIVESTOCK TRENDS - GREATBARRIER ISLAND Total Beef Cattle Total Sheep Total Year Cattle S. Us. Sheep S.Us. S. Us. 1942 10660 10707 908.6 19746 1950 888 10590 9728 8755 19345 1961 892 9746 10798 9720 19466 1970 2393 15482 10538 9480 24962 ,r;"- , 1979 2625 14437 9074 8170 22607 ~--; As the table shows, total stock units on the Island have remained relatively constant during this period. Since 1960 however, there has been a steady decline in dairy cow numbers to a point where no commercial herds are milked on the Isla nd today . This decline in dairy numbers has been coupled with a corresponding increase in beef cattle while sheep numbers have remained reasonably static. Many..areas have been repeatedly burnt as a means of clearing the scrub, and this practice has resulted in severe erosion on some of the poorer soils. The situation today is that only a few farmers are farming on a viable scale . 6.5.2 AGRICULTURALPOTENTIAL The Land Resource hventory shows the potential areas that could be used for pastoral farming on the Island. The classifica tion shows · the suitability of land in accordance with stock units. The classification being;- High 20 SUs/ha i".edium - 15 SUs/ ha Low 10 SUs/ha 38 The agricultural potential was then considered under ti,Q alternatives: Alternative A - Areas with very high values for uses other than agriculture (e .g . conservation, forestry, sanctuaries, existing reserves, etc .) eli minated from the suitability classification. Alternative 8 - Areas with~ values for uses other than agriculture eliminated from the suitability classification. The res ults are as follows:- Potential Area ( hectares) Medium Total Unsuitable Suitability (No constraints) 2270 9790 11360 23420 5230 Alternative A 1800 8570 7460 17330 1800 Alternative B 1430 5680 4440 11550 940 Pote ntial Stock Units Medium !:2!:!...