The Lake Clearwater catchment, in the Canterbury high country of New Zealand, has a native ecosystem that is adapted to low nutrient conditions. Wetlands in the catchment are identified by the Department of Conservation’s Arawai Kākāriki Wetland Restoration Programme as one of three important endemic wetland types in New Zealand. Uncertainty regarding diffuse nutrient load from agriculture into the lake and wetland ecosystems is limiting effective management of the catchment. This study investigated hydrological processes and nitrogen and phosphorus concentrations to improve knowledge of the sources, characteristics and magnitude of nutrient loading from agricultural land use in this 46 km2 high country catchment. Relevant hydrological data and literature pertaining to the catchment was extensively reviewed. In addition, flow for five key surface waterways was continuously logged at ten sites for 2 years. Concurrently, nutrient concentrations for total nitrogen, nitrate, ammoniacal nitrogen, total phosphorus and dissolved reactive phosphorus were measured at ten surface water sites and three groundwater sites. Total nitrogen and phosphorus load from farmland was calculated from annual flow and median concentrations for four waterways: farmland perennial stream runoff, farmland ephemeral stream runoff, a wetland channel below the farmed hillslope and the lake outlet. Similarly, total nitrogen and phosphorus load for unfarmed land was calculated from the flow and median concentration of two un-impacted perennial streams. Total nitrogen and phosphorus mass balances were calculated and used to estimate subsurface nutrient load and runoff volume from the farmed hillslope. Estimates of subsurface runoff were also made using Darcy’s equation and a water balance. Nutrient load predictions from the Catchment Land Use for Environmental Sustainability (CLUES) model were compared to measured loads. Nutrients were found to be elevated downstream of farmland, especially nitrogen, which was often above relevant guidelines and typical concentrations in upland waterways in Canterbury. Nitrate in farmland subsurface runoff was elevated and was estimated to contribute 52% of total nitrogen yield from farmland. Total nitrogen yield (1.96-2.94 kg ha-1 year-1) for farmed land was comparable to minimum values for pastoral land use in literature but total phosphorus yield (0.093-0.123 kg ha-1 year-1) was well below published values. The range in yield estimates is due to subtraction of a high and a low estimate of natural baseline yield from the measured in-stream yield. Total nitrogen export from the lake (2518 kg year-1) was greater than estimated input (1375 kg year-1) from farmed and non-farmed land indicating an additional source of nitrogen into Lake Clearwater. Total phosphorus export from Lake Clearwater of 58 kg year-1 was 24% less than total estimated loads into the lake (76 kg year-1) from farmed and non-farmed land. Phosphorus was not often above relevant guidelines and the median total nitrogen to total phosphorus ratio in Lake Clearwater (49:1) indicated phosphorus is the limiting nutrient in the lake. Because phosphorus was less elevated relative to nitrogen, an increase in phosphorus inputs could have a greater effect on productivity in the wetland and lake. With corrected land use information, total nitrogen loads predicted by the CLUES model were reasonable but total phosphorus loads were greatly overestimated. Investigation into potential impacts of the elevated nutrient loads described in this study on receiving native ecosystems is recommended to inform conservation efforts.

During recent years the high country of the South Island has attracted a good deal of attention from farm economists, soil conservationists, geographers and also politicians. With the present need for increased national production the problem of keeping the high country in productive occupation is the subject of justifiable concern. The purpose of this regional study is to describe one of the most distinctive areas in the high country, and to discuss the problems which have caused the recent Royal Commission on the Sheep-farming Industry in New Zealand to investigate the general economic position of the runholders. Besides being a well-defined physiographic unit, the Mackenzie Basin or, as it is better known to the local people, the Mackenzie Country has a distinctive character of its own. On entering Burkes Pass even the most casual observer cannot fail to notice how different the landscape within the basin appears compared with that outside. This large, gravel-filled intermontane depression with its vast expanse of dun coloured tussock and its clear, dry climate seems to have a special flavour which distinguishes it from any other part of either Canterbury or Otago. Probably the most striking feature of the basin is its monotonous uniformity of both physical conditions and human activities. The extensive sheep-farming economy has imposed a distinctive pattern of land use over the whole area. Not only does the landscape have a similar appearance everywhere but, because of their common int erests, the people all tend to live alike and think alike. Before 1939 the basin was solely a sheep-grazing area but, with the recent developments connected with the storage of water in the lakes for the generation of hydro-electricity, the Mackenzie Country has assumed a new importance. With the dam-building schemes at Tekapo and Pukaki an entirely new element has been introduced into the landscape - the large Public Works Camp. These camps, however, are, for the most part, temporary features and the sheep-station remains the typical unit of settlement. For this reason the major part of this study is devoted to a description of the landscape as it has developed under the extensive sheep-farming economy and a discussion of the problems resulting from the exploitation of the natural vegetation. When the early settlers first took up their runs they had the opportunity of making the Mackenzie basin one of the best merino grazing areas in New Zealand. In most cases that opportunity was lost, due partly to ignorance of proper grazing methods under sub-humid conditions and partly to short-sighted practices caused by temporary economic difficulties. Over-burning and over-stocking extracted an early toll from the vegetation cover which, in spite of numerous attempts can never be fully repaid. By deliberately introducing rabbits into the area the early runholders made their third and possibly their greatest mistake. These rabbits were allowed to multiply unchecked for nearly twenty years before it was realised what a menace they were likely to become. By that time it was too late. Today, the rabbit is generally considered to be the chief cause of the disturbing decline in the sheep carrying capacity of the Mackenzie Country. Altogether, unwise burning, overstocking and rabbits have caused such a deterioration in the tussock cover that Cumberland's description of some parts of the basin as "deserts in the making" is quite appropriate. Admittedly conditions are not as bad as in the "man-made deserts" of Central Otago but a serious problem at present confronts the Mackenzie runholders.

During recent years the high country of the South Island has attracted a good deal of attention from farm economists, soil conservationists, geographers and also politicians. With the present need for increased national production the problem of keeping the high country in productive occupation is the subject of justifiable concern. The purpose of this regional study is to describe one of the most distinctive areas in the high country, and to discuss the problems which have caused the recent Royal Commission on the Sheep-farming Industry in New Zealand to investigate the general economic position of the runholders. Besides being a well-defined physiographic unit, the Mackenzie Basin or, as it is better known to the local people, the Mackenzie Country has a distinctive character of its own. On entering Burkes Pass even the most casual observer cannot fail to notice how different the landscape within the basin appears compared with that outside. This large, gravel-filled intermontane depression with its vast expanse of dun coloured tussock and its clear, dry climate seems to have a special flavour which distinguishes it from any other part of either Canterbury or Otago. Probably the most striking feature of the basin is its monotonous uniformity of both physical conditions and human activities. The extensive sheep-farming economy has imposed a distinctive pattern of land use over the whole area. Not only does the landscape have a similar appearance everywhere but, because of their common int erests, the people all tend to live alike and think alike. Before 1939 the basin was solely a sheep-grazing area but, with the recent developments connected with the storage of water in the lakes for the generation of hydro-electricity, the Mackenzie Country has assumed a new importance. With the dam-building schemes at Tekapo and Pukaki an entirely new element has been introduced into the landscape - the large Public Works Camp. These camps, however, are, for the most part, temporary features and the sheep-station remains the typical unit of settlement. For this reason the major part of this study is devoted to a description of the landscape as it has developed under the extensive sheep-farming economy and a discussion of the problems resulting from the exploitation of the natural vegetation. When the early settlers first took up their runs they had the opportunity of making the Mackenzie basin one of the best merino grazing areas in New Zealand. In most cases that opportunity was lost, due partly to ignorance of proper grazing methods under sub-humid conditions and partly to short-sighted practices caused by temporary economic difficulties. Over-burning and over-stocking extracted an early toll from the vegetation cover which, in spite of numerous attempts can never be fully repaid. By deliberately introducing rabbits into the area the early runholders made their third and possibly their greatest mistake. These rabbits were allowed to multiply unchecked for nearly twenty years before it was realised what a menace they were likely to become. By that time it was too late. Today, the rabbit is generally considered to be the chief cause of the disturbing decline in the sheep carrying capacity of the Mackenzie Country. Altogether, unwise burning, overstocking and rabbits have caused such a deterioration in the tussock cover that Cumberland's description of some parts of the basin as "deserts in the making" is quite appropriate. Admittedly conditions are not as bad as in the "man-made deserts" of Central Otago but a serious problem at present confronts the Mackenzie runholders.

Podocarpus cunninghamii is an endemic New Zealand conifer that, in pre-human times, formed extensive forest communities across the eastern South Island high country. Anthropogenic disturbances have reduced the distribution of Podocarpus cunninghamii communities such that they now exist mainly as small and isolated remnants within a highly modified, predominantly pastoral landscape. Very little is known of the ecology of high country Podocarpus cunninghamii communities, and without this information it is not possible to develop an ecological basis for their restoration. This thesis explores the ecology of Podocarpus cunninghamii in the eastern South Island high country, investigating factors that potentially affect the restoration of Podocarpus cunninghamii within this environment, with special attention paid to the role of arbuscular mycorrhizal fungi (AMF). Field investigations of Podocarpus cunninghamii communities showed that they contain a high degree of floristic and structural variation determined by soil and climatic variables. Analysis of age and size class distributions suggest that Podocarpus cunninghamii has more than one regeneration strategy, and can regenerate within intact forest following the opening of small canopy gaps or can undergo large-scale recruitment following catastrophic disturbance. Field and glasshouse experiments investigating growth and nutrient responses of Podocarpus cunninghamii to different AMF inoculants found that Podocarpus cunninghamii responses are dependent on both AMF type and grass competition. Finally, investigation of Podocarpus cunninghamii carbon stocks showed that they are less than that of other New Zealand forest types, but are greater than that of grazed pastures. Successful restoration of high country Podocarpus cunninghamii communities will require the incorporation of associated species based on local environmental conditions, and will also need to allow for disturbance processes. AMF may have an important role to play in restoration by reducing seedling production times and by increasing the competitiveness of Podocarpus cunninghamii when in competition with exotic grasses.

This study was undertaken to research the principles and practices behind increased pasture productivity on Longslip Station, Omarama. A range of landscape - soil - climate - plant systems were identified, then analysed and the legume responses measured. By isolating cause and effect and appreciating the driving variables of each system, lessons learnt could be reliably and objectively transferred to the rest of the farm. Extrapolation to the balance of the property (15,150 ha) permitted immediate large-scale development and engendered confidence to lending institutions, Lands Department, catchment authorities and ourselves. Soil (land) cannot be well managed and conserved unless it is mapped reliably and its characteristics measured and interpreted by skilled observers (Cutler, 1977). Soil resource surveys, and their interpretation, are an essential ingredient of rational resource evaluation and planning. This thesis is a figurative and comparative survey and study of the soil catenary bodies, resident vegetation, legume establishment and pasture production characteristics of a 400 hectare catchment, in relation to, and as influenced by soil landscape unit, slope component, altitude, aspect and time. The inherent diversity in landform, soil properties and vegetation communities in a single catchment in the high country has not previously been fully studied or appreciated. This has lead to blanket recommendations for fertilizer, seed and management regimes both within and between properties and even regions. This study reports on the diversity of, yet predictable change in soil properties with slope position (upper, middle and lower) aspect and altitude in terms of both soil physical properties e.g. soil depth and water holding capacity and soil chemical properties such as pH, BS%, %P, %S, %N and %C. The composition of the resident vegetation and its differential response to oversowing and topdressing and subsequent change through time is reported and discussed. Finally an epilogue gives an insight into the problems and frustrations of farming practices in the high country from a motivation and personal perspective and political point of view that it is essential to come to terms with.