David Rhodes is Senior Policy
Analyst in the Ministry of
Agriculture and Forestry,
Wellington, New Zealand.
Government-encouraged reforestation of land that was heavily eroded through long-term sheep and cattle farming gives the soil a second chance.
East Coast Region
A place for everything and everything in its place.
Mrs Isabella Beeton
The East Coast of New Zealand's North Island is characterized by steep slopes once covered by native forests which were cleared for agriculture - primarily sheep and cattle farming - after the arrival of European settlers in the nineteenth century. After clearing, these slopes were subject to severe erosion and loss of soil fertility, which ultimately threatened the region's economic well-being. Parts of the East Cape region have been described as examples of the worst pastoral erosion in the world, and the legacy of deforestation remains today. This article documents efforts to reverse the damage through tree planting, beginning with government efforts starting in the middle of the twentieth century and continuing, after privatization of the Forest Service in 1987, with the East Coast Forestry Project, a scheme that encourages private planting. The article examines the project's environmental and social impacts, including preservation of the soil and provision of employment.
The area defined by the Gisborne local government boundary on the East Coast of New Zealand's North Island encompasses around 850 000 ha of highly erosion-prone land. Soils are largely derived from sandstone and mudstone, together with some volcanic pumice soils. Intense geological activity has shattered the mudstone and sandstone, and water is easily able to penetrate. Continual wetting and drying cause the rock, particularly the mudstone, to disintegrate.
Summers are warm and dry with temperatures frequently exceeding 30oC, and droughts are common. Annual rainfall ranges from 1 000 to 5 000 mm, and heavy rain (100 to 300 mm within 24 hours) is common in both summer and winter.
Around two-thirds of the area, and much of the pastoral land, is drained by two rivers - the Waipaoa and the Waiapu (see Map).
Prior to European settlement most of the land was covered by native forest comprising podocarps and mixed hardwoods, particularly on the lower slopes. At higher elevations, red and silver beech forests predominated. Even under forest the land was erosion prone, and some large slips and earth movements occurred.
European settlers arrived in the late 1800s and, as immigration grew, the clearance of the forest accelerated. Propelled by the advent of refrigerated shipping, between 1890 and 1900 over one-quarter of New Zealand's forest was cleared, predominantly for livestock grazing. Much of this clearance was from steep marginal land.
Land development for agriculture was driven by economics. Protectionist policies developed by the government from the 1930s on played a part, as did aerial top-dressing in the 1940s and a wool boom in the 1950s. From the 1960s onwards successive governments sought to offset decreasing agricultural returns through such incentives as fertilizer subsidies, tax breaks for development and discounted loans. A Livestock Incentive Scheme provided payments for increasing stock numbers (with the result that a number of farmers put on more stock than their farms could support). In 1978 a Land Development Encouragement Loan was introduced to increase land production; the loan would be written off if the land was kept in a developed state for five years. Priority was given to clearance of unimproved or reverted hill-country land (Ministry of Agriculture and Fisheries, 1981). The same year, a Supplementary Minimum Price scheme was also brought in, which guaranteed prices to farmers for several years ahead.
Forest clearance through the first half of the twentieth century, primarily for livestock farming, resulted in severe soil slippage in the pastoral headwaters
- GISBORNE DISTRICT COUNCIL, NEW ZEALAND
By 1900 the effects of forest clearance were apparent. Many new slips, earthflows and slumps appeared or were reactivated, and gullies began to form (WSD, 1987). River channel aggradation (modification of channel slope through deposition) increased in volume and geographic distribution from 1910 onwards. By the late 1930s downstream residents were raising concerns about the impact of unchecked erosion in the headwaters. Analysis of the sediment record of a lake to the south of the East Cape region showed that the natural erosion rate prior to human settlement was 2.1 mm per year but that by the 1990s it had reached 14 mm per year (Trustrum and Page, 1991).
The material carried downstream overwhelmed many fertile river terraces and resulted in the loss of the land carrying the most livestock. Numerous cases of riverbed rises of 10 to 30 m were recorded following conversion of land to farming (WSD, 1987). In addition to the loss of much productive land, financial impacts included stock losses and the costs of rebuilding or repositioning roads, embankments, water storage and supply facilities, irrigation systems, fences, bridges and homesteads.
By 1960 the East Coast region had fallen well behind the socio-economic position of the country's other livestock farming regions. The region was suffering from out-migration, economic stagnation and high unemployment, due in part to loss of soil fertility and soil erosion. The relative isolation of the area, land tenure inflexibility, the large size of farm holdings (typically more than 800 ha) and labour recruitment problems compounded the situation. In 1962 the real capital values of the land in the most severely eroded areas were half what they had been in 1919 (WSD, 1987). By the late 1960s all of the major secondary industries (e.g. dairy factories and freezing works) outside Gisborne city had closed, and health, school, transport and other services were threatened.
The situation had a significant impact on local indigenous (Maori) tribes. The East Coast has the highest proportion of Maori people of any region in New Zealand. The Maori have significant tribal landholdings in the region and a strong cultural association with the land. Lack of financial capital and multiple ownership, however, restricts land development options. Compounding this situation are lower than average rates of tertiary education, higher unemployment and other social problems. The greater part of the Maori population migrated to the cities in search of work.
The impact on the land was long term. Even without further erosion, recolonization of steep slopes by pasture takes about 30 years (Hicks, 1989), and soil fertility only recovers to around 80 to 85 percent of its prior level even with oversowing and top-dressing. Erosion rates under farming were generally much greater than soil formation rates. The Ministry of Works and Development (WSD, 1987) concluded that "pastoral farming cannot be considered a sustainable land use on much of this hill country".
Creek and silt covered farmland north of Tokomaru Bay - an example of how erosion in the headwaters resulted in loss of productive land downstream
- NEW ZEALAND MINISTRY OF AGRICULTURE AND FORESTRY
Mangatuna Bridge north of Tolaga Bay, flooded out as a result of sedimentation with eroded material carried downstream
- NEW ZEALAND MINISTRY OF AGRICULTURE AND FORESTRY
The local Poverty Bay Catchment Board began experimental planting of trees in the area in 1948. These plantings quickly established that once a canopy had formed, runoff was considerably reduced and earthflows and expansion of gullies were slowed. However, attempts to stabilize riverbeds and gullies were futile.
Influenced by these results the government tasked the New Zealand Forest Service in 1960 with purchasing and planting an initial 7 000 ha of at-risk land. Various erosion control options were then assessed, including conservation farming. A multidisciplinary independent committee recommended in 1967 that a line be drawn between the more fertile pastoral river flats ("pastoral foreland") and the critical headwaters, and that the whole of the latter area be afforested, even if this meant taking pastoral land out of production (Taylor, 1970).
The government responded by expanding the New Zealand Forest Service programme to purchase and plant the unforested parts of the headwaters to control erosion and enhance productivity. Secondary objectives were to maintain the productivity of the land, promote economic and social development and establish production forests.
The simple segregation of the headwaters from the pastoral foreland was not well supported by the local farming community, and early forest planting was slow. By the mid-1970s it was apparent that this distinction was no longer appropriate and the following categories for land use decisions were developed (PBCB, 1978):
These more tailored land categories achieved wider acceptance. Government afforestation was refocused on Category 3 land, divided into the following subcategories:
1984 saw a significant shift in government philosophy towards greater reliance on the free market. Central government began to exit from a range of service areas in favour of private provision of those services, except where it was considered that the public good necessitated government presence. A range of new government policies was consequently adopted. Partial cost recovery was introduced for services, concessionary loans were phased out, subsidies were removed and import protection was substantially lowered. More responsibility was placed on land users to accept the consequences of their land management decisions. Subsidization was only considered where action was urgently required and the resources were beyond the capacity of the individual. From this time on the government also sought to exit from forest ownership and to privatize its holdings.
After 1984/85 the combined decline in government assistance and agricultural prices had major impacts. Registered unemployment on the East Coast was 14.3 percent in 1987, the highest in the country. Half of this unemployment was estimated to be due to jobs lost between 1985 and 1987 (WSD, 1987). Forestry development required early expenditure, while the returns would appear many years hence. Decades of continually decreasing rates of real return encouraged farmers to respond by increasing stocking rates instead.
The planting programme ended in 1987, when the Forest Service was corporatized. The new Forest Corporation was commercially focused and the highly erodible land was not seen as economically viable. A review of the planting programme found that forestry had helped control erosion and maintain productivity, but although 36 100 ha had been planted over 16 years, at least another 110 000 ha needed treatment (WSD, 1987). Downstream control of aggradation rates and flood yields was minor. The reasons given were that:
Harvesting from the early government-established forests commenced in 1990. By the mid-1990s Mangatu forest (13 000 ha), for example, was producing around 250 000 tonnes of logs per year.
Category 3 land at Mangatu forest, inland from Gisborne, in 1964
- NEW ZEALAND NATIONAL ARCHIVES - JOHN JOHNS COLLECTION
An early forestry response: the Mangatu forest site in 1970 showing successful afforestation
- NEW ZEALAND NATIONAL ARCHIVES - JOHN JOHNS COLLECTION
Three months after the review in 1987, the area was struck by an intense tropical cyclone called Bola, which brought wind and rains on a scale witnessed only about once a century. Over three days in March 1988 much of the hill country received 600 mm of rainfall. The epicentre was inland from Tolaga Bay, where a peak of 900 mm was recorded.
The results were dramatic. The hills were extensively scarred and the valley floors blanketed with silt. The cyclone increased the land classified as "of no productive use" from 38 000 ha to 41 000 ha (Hogan, 1990). In the Waihora catchment alone, the area requiring afforestation increased by a factor of six over the 1983 requirements (ECCB, 1998).
Erosion was measurably lower in forested areas than in non-forested areas (Kelliher, Marden and Watson, 1992). Aerial photographs of the Hawkes Bay region just to the south the East Cape revealed surface instability on 0.1 percent of the afforested catchment, compared with 0.9 percent of the pastoral catchment (Fransen and Brownlie, 1996). The event demonstrated that commercial production forests were a feasible option for controlling erosion. Tree canopy closure, however, is critical, and pine trees less than six years of age (which did not provide canopy closure) did not protect the soil, producing no greater resistance to erosion than pasture (Marden and Rowan, 1993).
Following Cyclone Bola, the government provided short-term financial relief to farmers through a Farm Assistance Fund. Farmers were compensated to 60 percent of their total non-insurable losses and expenditure was left to their discretion. Most of the money was used to retire debt, and few farmers made changes to their land management practices. Little was spent on erosion control. It was concluded that the financial assistance had achieved little change and would not prevent a similar disaster in the future (Webber et al., 1989).
The general downturn in the economics of sheep and beef farming combined with the effects of Cyclone Bola caused a reassessment of approach. Erosion problems had become more serious, and permanent land management changes on a large scale were necessary (Nield and Kirkland, 1988). The area from Tolaga Bay to Te Araroa, in particular, had received little attention, apart from some conservation forestry planting, and the condition there had worsened. The government began considering ways of accelerating the rate of planting at the lowest cost to the State. Another factor in the need for a new approach was that, consistent with the economic reforms, the government was exiting from forest ownership and was selling its forests on the East Coast.
In 1992 the East Coast Forestry Project was introduced with the aim of "promoting large-scale commercial forestry as a means of controlling soil erosion, providing employment and regional development and to recognize environmental needs on individual properties" (MOF, 1994). The goal was to facilitate planting on 200 000 ha of moderately to severely eroding land over 28 years.
The objectives of the East Coast Forestry Project are aligned with the aims set out in the District Plan of the Gisborne District Council under the Resource Management Act (1991). The Resource Management Act is the cornerstone legislation in New Zealand covering management of the environment across all landscapes, and responsibility for its implementation is vested in local government - the regional and district councils. The Gisborne District Council is thus closely involved in the management of the project.
In contrast to earlier State initiatives, the East Coast Forestry Project encourages private planting. A tendering process is employed whereby applicants submit forest development plans for funding consideration, and grants are available for silvicultural regimes for approved commercial species. Applications are assessed against certain criteria (e.g. the existence of a forest management plan, a minimum of 5 ha, at least a certain percentage of target land and exclusion from clearance of any emerging indigenous tree species) and then ranked by cost after the bids are weighted in favour of those that include a greater percentage of target land and/or retain a larger percentage of indigenous vegetation. Thus a certain degree of erosion control is required as a minimum, and thereafter the bids that achieve this most economically are favoured. Bids are also adjusted on the basis of transport rates and distances to ensure that the more remote parts of the district are not disadvantaged. Precise details of the parameters used to prioritize the tenders are commercially sensitive and kept confidential.
An upper funding limit for individual grants is established each year. This figure is a net present value (NPV) derived using discounted cash flow over a 29-year rotation. Prices are taken from current log prices. The discount rate is based on the real rate of return for a selected private-sector forestry investment and has ranged from 9 to 12 percent. A negative NPV indicates the size of payment needed to encourage an investor to consider the erosion-prone land on comparable terms with other land. This level is then increased by an additional confidential amount to cater for additional "risk", to provide a ceiling above which tenders will not be accepted. When there is sufficient competition, as has happened in recent years, the NPV is not required.
Grants are paid out in instalments upon satisfactory completion of work, and the tendering process allows the government to select only the best proposals and to limit its total financial outlay to approved grants. As forestry becomes more prevalent, tenders are expected to become increasingly competitive, with consequently reduced cost to the government.
Indigenous forest cannot be cleared under the project and some assistance is given for its protection. Protected areas and riparian strips are excluded from clearance.
Radiata pine is the most cost-effective planting option (over 95 percent of all planting to date). Growth rates of radiata pine on the East Coast are some of the highest in the country, and average tree height at age 20 is 28 m. Most other species have comparatively slow growth rates, and natural regeneration can be relatively slow to establish. Eucalyptus and Acacia species are more susceptible to ground movement and dry soil conditions. Willows and poplars are only suitable for small areas. Douglas fir is an alternative in higher-altitude, colder areas. Neither Pinus radiata nor Douglas fir is suitable for planting within very active gullies, but both provide suitable peripheral planting.
Canopy closure and occupation of the site by roots are achieved earlier with higher stocking rates, so minimum stocking specifications are set. For example, a mandatory final thinning is to occur by a mean tree height of 15 m, and at this height the stocking is to be in the range of 250 to 500 stems per hectare. Yields per stocked area are comparable to those of non-subsidized commercial areas on less steep terrain, at around 600 m3 per hectare. Quality, however, is not as good.
Aerial view of large-scale planting of two-year-old radiata pine under the East Coast Forestry Project on headwater land displaying severe soil erosion
- D. RHODES
The 1987 review of the government afforestation programme (WSD, 1987) found that employment had been provided to over 200 people, mostly Maori. Employment was provided particularly for younger age groups, which had accounted for 50 percent of the out-migration. During the late 1970s the rate of population decline slowed, partly as a result of forestry development. Dependence on agriculture was reduced, and a more stable money supply was produced in an area that had had a history of seasonal income (Aldwell, 1982). It was somewhat early, however, to be measuring indirect benefits, especially given the momentum of past decline.
Since then more evidence has been produced. The neighbouring Wairoa District experienced the same economic downturn and impact from Cyclone Bola, and from 1992 to 1995 its forest planting rates were similar to those of the East Coast Forestry Project. The competition for pastoral land drove up land prices significantly. Similarly, prices paid for pastoral land in Gisborne District increased from half the New Zealand average in 1992 to greater than the average in 1994 (MAF, 1999). Forest employment increased rapidly in Wairoa District between 1992 and 1995, and total unemployment fell by more than 25 percent (King, Krause and Butcher, 1997; J. King, personal communication). The growth of forestry had some negative impacts, however, particularly on businesses servicing agriculture (e.g. shearing gangs, fertilizer manufacturers and fencing suppliers) and on rural social structure, at least from the viewpoint of the farming community. The primary impact, however, was increased employment. For Wairoa, it was estimated that even if the rate of planting were substantially reduced, and assuming there were no processing facilities, there would be an 18 percent net increase in household income and a net increase in jobs when the forests reached maturity (King, Krause and Butcher, 1997).
A 1996 assessment of the East Coast Forestry Project concluded that, even allowing for the loss of farming employment, the project would provide a steady increase in employment through 2005, and even prior to harvest there would still be more jobs than in the absence of the scheme. Following the commencement of harvesting, 3 800 jobs will have been created, over and above any losses (Butcher Partners Ltd, 1996). Of the increased silvicultural workforce associated with the project in 1997, 62 percent had not worked in forestry prior to 1993. Ninety percent lived in or adjacent to the region, although 23 percent had lived there for less than one year, indicating a strong inflow from outside the region. Maori participation, at 72 percent, was significantly higher than the national average (52 percent), and 81 percent of the Maori were from tribes within the project catchment (Cummins and Byers, 1997).
The development of some processing capacity has further lifted employment. In the decade 1990 to 1999, employment in forestry and first-stage processing on the East Coast increased almost sixfold from 125 to 723 full-time equivalents (Brown, 2000). The government assisted planting has supplemented non-assisted planting that has taken place on the less steep country and has thus added to the critical mass needed for developing processing facilities. Of the 50 000 ha planted between 1989 and 1993, for example, 15 500 ha had government assistance while the rest was unsub-sidized (MAF, 1999).
Key changes to the East Coast Forestry Project
Reviewing and refocusing efforts over time is important, and following a 1998 review the East Coast Forestry Project policy and regulations were modified (see Box). The most fundamental change was to combine the project's four previous objectives into a single objective: sustainable land management through changing pastoral land use in any cost-effective way. A key attribute of the afforestation solution is that it can deliver multiple benefits. However, the government concluded that an explicit overriding objective was needed to avoid confusion and even contradiction between multiple objectives and the means of achieving them. Given the impact of erosion on economic activities, the government decided that erosion control was sufficient primary justification for the project. The other benefits are considered important but secondary benefits.
Funding remains the same but is retargeted to the 60 000 ha of most severely eroding land (Categories 3b and 3c and peripheral planting on land in Category 4). Sustainable management through controlling present and potential erosion of the target land is to be achieved by 2020.
The costs of establishing fencing around indigenous reserves are now reimbursed. Grants are still available for planting and final thinning, but pruning has been excluded because it is not considered an erosion-related activity. Also, a uniform stocking rate for target land (1 200 stems per hectare) has replaced a density prescription which varied with the magnitude of erosion. The latter system was found to be impractical because planting sites typically contained varying levels of erosion risk within the same area. The use of a sufficiently sensitive land classification system as the basis for land use decisions has been critical.
Forestry has proved a successful tool in facilitating long-term land use change. However, the growth rates of roots and canopy need to keep pace with erosion rates, and the use of rapidly establishing, relatively inexpensive species is fundamental. Pinus radiata provides soil conservation benefits for about 40 years and is easily managed on a commercial 30-year rotation. It is expected that with the cash flow from the first rotation and the development of infrastructure, replanting will be an economically logical choice. However, erosion control methods other than large-scale commercial forestry are now eligible for consideration. Examples include indigenous scrub reversion and gully plantings.
The 1987 review recognized the importance of the non-erosion control benefits to local community goals and priorities and recommended that a local coordinating committee manage the programme. While the East Coast Forestry Project is managed by the Ministry of Agriculture and Forestry on behalf of the New Zealand Government, it has a multi-agency technical advisory committee, including the Department of Conservation, the Ministry of Maori Development and a local Gisborne District Advisory Committee, which considers and makes recommendations on each tender round.
Parts of the East Cape region have been described as examples of the worst pastoral erosion in the world, and the legacy of deforestation remains today. Some of the severely eroding gullies will not be stabilized even by planting and will remain as permanent scars, but afforestation has been demonstrated to be effective in arresting incipient gullies in geologically similar terrain. Localized erosion as severe as that experienced during cyclone Bola occurs during storms of lesser magnitude but greater frequency (Kelliher, Marden and Watson, 1992). With increasing erosion control through the expansion of forestry, however, the impact of these storms will continue to diminish.
The proportion of non-subsidized planting has increased steadily since the 1970s, although these plantings have been largely confined to the easier categories (1, 2 and 3a) of the pastoral foreland in the south of the region. Overall, between 1993 and 1999 new plantings were approximately evenly divided between the East Coast Forestry Project (45 percent) and private ventures (55 percent) (R.C. Hambling, personal communication), but in 1997, for example, private plantings accounted for about 75 percent of new plantings in the Gisborne District (MAF, 1999).
The supply of wood from all planted forests in the region is forecast to increase from 650 000 m3 in 2000 to 2.67 million cubic metres in 2010 - a fourfold increase (MAF, 2000). Processing facilities now include a laminated veneer lumber mill, two medium-capacity sawmills and three small sawmills. Current direct and indirect employment generated by forestry on the East Coast is estimated at 1 301 full-time equivalent jobs, and it is projected that forestry-related development will create around 2 300 new jobs by 2010 (Brown, 2000).
Land-use change on this scale has a number of social implications, not all of them positive. Early forestry planting in the area encountered strong opposition from both farmers and local authorities because of concerns that it would lead to rural depopulation, undermine the viability of local communities and result in a loss of rural services (Cocklin and Wall, 1996). Typically, the distribution of the forestry workforce favours the townships, and this can be at the expense of rural valley and farming communities. Net gains in income and employment may not be equitably spread. For much of the land, however, pastoral farming was clearly unsustainable in the long term, and change was necessary. The change in the landscape has also been matched by a change in local attitudes to forestry, with greater recognition now of the long-term regional economic development, employment and soil conservation benefits (Cocklin and Wall, 1996).
Long-term planning is necessary to ensure that the economic benefits of the wood supply are captured locally (Aldwell, 1982; King, Krause and Butcher, 1997). Energy constraints, skilled labour shortages, distances to port and undeveloped infrastructure (particularly the typically unsealed roads, in need of upgrading) are important challenges now being confronted by the government and the community. It is surely a healthy sign that this focus has replaced the earlier contemplation of whether the land, and those activities and livelihoods that depended on it, had a future.
Aldwell, P.H.B. 1982. Impacts of large-scale forestry on settlement and servicing patterns in Waiapu County. Planning Quarterly, 68.
Brown, C. 2000. Employment potential through forestry on the East Coast. Working Paper. Wellington, New Zealand, Ministry of Agriculture and Forestry.
Butcher Partners Ltd. 1996. The impacts of the East Coast forestry scheme on employment and economic structure in the Gisborne Region. Report prepared for the Ministry of Forestry, Christchurch, New Zealand.
Cocklin, C. & Wall, W. 1996. Attitudes towards forestry in the East Coast region. New Zealand Journal of Forestry, 41(3): 21-27.
Cummins, T. & Byers, J. 1997. East Coast silvicultural workforce 1996. Rotorua, New Zealand, Logging Industry Research Organisation.
East Cape Catchment Board and Regional Water Board (ECCB). 1998. Waihora catchment Cyclone Bola storm survey. Gisborne, New Zealand.
Fransen, P. & Brownlie, R. 1996. Historical slip erosion in catchments under pasture and radiata pine forest, Hawke's Bay hill country. New Zealand Forestry, 40(4): 29-33.
Hicks, D.L. 1989. Economic impact of farm conservation on hill country: some information from Cyclone Bola. Technical Record PN4. Aokautere, New Zealand, Division of Land and Soil Sciences, Department of Scientific and Industrial Research (DSIR).
Hogan, J. 1990. The wounded land. A legacy of neglect. Growing Today, April.
Kelliher, F.M., Marden, M. & Watson, A.J. 1992. Stability of land and tree planting density East Coast, North Island. Forest Research Institute Contract Report FWE 92/13. Wellington, New Zealand, Ministry of Forestry.
King, J.M., Krause, M.K. & Butcher, G. 1997. Impacts of land use change in Wairoa District. Resource Document. Wellington, New Zealand, Ministry of Agriculture.
Marden, M. & Rowan, D. 1993. Protective value of vegetation on tertiary terrain before and during Cyclone Bola, East Coast, North Island, New Zealand. New Zealand Journal of Forest Science, 23(3): 255-263.
Ministry of Agriculture and Fisheries. 1981. Rural industries incentives 1981-82. Wellington, New Zealand, Ministry of Agriculture and Fisheries.
Ministry of Agriculture and Forestry (MAF). 1999. East Coast Forestry Project. Wellington.
MAF. 2000. National exotic forest description national and regional wood supply forecasts 2000. Wellington.
Ministry of Forestry (MOF). 1994. A guide to the East Coast Forestry Project 1994. Wellington, New Zealand.
Nield, J. & Kirkland, W. 1988 . Sustainable land use in the East Coast Region of the North Island. Palmerston North, New Zealand, Envirotech.
Poverty Bay Catchment Board (PBCB). 1978. Report of land use planning and development study for erosion prone land of the East Cape Region (Red Report). Gisborne, New Zealand.
Taylor, N.H. 1970. Wise land use and community development. Report of the Technical Committee of Inquiry into the problems of the Poverty Bay - East Cape District of New Zealand. Wellington, New Zealand, Water and Soil Division, Ministry of Works and Development.
Trustrum, N. & Page, M.J. 1991. The long-term erosion history of Lake Tutira watershed: implications for sustainable land use management. In P.R. Henriques, ed. Proceedings of the International Conference on Sustainable Land Management. Hawkes Bay, New Zealand, Napier.
Water and Soil Directorate (WSD). 1987. The East Coast Project review. Wellington, New Zealand, Ministry of Works and Development.
Webber, D., Buchan, D., Rivers, M. & Rayner, T. 1989. Cyclone Bola Agricultural Assistance Scheme. Economic and Social Impact Study. Wellington, New Zealand, Ministry of Agriculture and Fisheries.