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    Economic evaluation of the integrated rehabilitation and management of critical watershed in the Philippines : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Philosophy in Natural Resource and Environmental Economics at Massey University
    (Massey University, 1995) Umadhay, Gideon Antiojo
    The impacts of upper watershed land use practices on resource systems on-site and downstream have long been recognised as a major problem area in resource management in the Philippines. Increasing population levels and upland migration have worsened this problem with time. The consequences are seen in loss of upland productivity, poverty for upland farmers, loss of biodiversity, soil erosion, river siltation, sedimentation of reservoirs and irrigation systems, impacts on estuarine mangroves and coastal fisheries, increased flooding and drought, and so on. There is an urgent need to protect the resource system while at the same time providing for the needs of the upland population. Watershed rehabilitation is proposed as a strategy to achieve this. Watersheds comprise of a sequence of linked resource systems which complicates the integrated rehabilitation and management of them. Management is also complicated by the fact that different agencies have responsibilities over different parts of the watershed and that the private parties within the watershed are there often illegally. Hence, any rehabilitation scheme needs to provide ways to make occupation legal for illegal occupants and at the same time provide incentives for them to cooperate with the rehabilitation strategy. In other words, any proposed scheme must be profitable to the occupants. This study describes a strategy for watershed rehabilitation and analyses a case study example. The project's aim is to integrate social development and watershed rehabilitation. The social development component looks at people participation and the provision of land and opportunities to produce food. The rehabilitation component deals with reforestation and agroforestry to reduce soil degradation and increase water flow. The project involves reforestation of 950 hectares, agroforestry on 3070 hectares, assisted natural regeneration of 716 hectares and production of agricultural crops on an area of 450 hectares. The objectives of the study are to investigate watershed rehabilitation in terms of economic desirability, socio-economic impact and possible implementation constraints. A Benefit-Cost analysis on the data obtained from a feasibility study shows that the project, from an economic point of view. is very worthwhile. The sensitivity analysis further shows that the results are also very robust. Implementation however, will not be an automatic process and the good economic results are not a foregone conclusion. Success of the project will to a large extent depend on cooperation by the occupants of the watershed. Recommendations are made as to how this cooperation can be achieved. Overall however, the study shows that watershed rehabilitation is a strategy that is desirable from an economic and social point of view as well as clearly contributing to sustainable development of the Philippines.
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    Factors affecting the soil binding capacity of the root systems of some populus and salix clones : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Botany at Massey University
    (Massey University, 1973) Hathaway, Robert L
    Man-induced changes in the vegetation of New Zealand over the last century have resulted in large areas of actively eroding land, both in the steeplands which still retain a form of forest cover, and in large areas of moderate to steep hill country cleared for pastoral use. By 1941, the seriousness of the problem had been recognised, and Catchment Authorities were constituted, under the auspices of the Soil Conservation and Rivers Control Council, to undertake river and erosion control programs. Many techniques were used in erosion control work, but most emphasis has been placed on the planting of trees, largely Populus and Salix species. The planting of trees has proven to have a beneficial effect on counteracting erosion by slumping and gullying, both in retired areas and in those still grazed. It may be assumed that this effect is due primarily to the reinforcing and binding effect of their root systems. The reduction of soil moisture by evapotranspiration is considered to be of secondary importance, as water loss from these deciduous trees is very low in winter, which is the period of maximum soil moisture content and thus maximum instability. In the past, the selection of poplars and willows for erosion control purposes has been based on the growth and characteristics of the shoot of the tree, while almost nothing was known of the root systems. Variations in morphology and strength of root systems obviously are important factors in the selection of the most suitable species or varieties for soil stabilisation purposes. Objectives of the study The primary objective of the study was to Investigate the morphology, anatomy, and soil binding capacity of the root systems of a representative number of Populus and Salix clones, in order to determine whether any of the clones were likely to be superior for soil stabilisation purposes, and to determine which characteristics of the root systems were most important for this purpose, as a basis for the selection of improved varieties.
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    The benefit of soil erosion control in Palmerston North and surrounding areas : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Agricultural Economics in Resource Economics at Massey University
    (Massey University, 1993) Rosawati, Endang
    Soil erosion is a major cause of land degradation in New Zealand. In the Manawatu area, including Palmerston North, the conversion of original vegetation to farm land, began at the time of its settlement by Europeans in the 1850's. This left rivers free to erode alluvial banks and change course, resulting in significant areas of high quality alluvial soils being replaced with poor quality gravels. Soil erosion also imposed substantial costs on the community through the loss of pastoral production and soil fertility, widespread damage to public and private assets, a reduction in water quality through sedimentation, and degradation of the habitat for wildlife and in-stream biota. Soil conservation activities produce benefits that do not only accrue to the land owners, but also to others in the region and to future generations. However, identification of the off-site benefits of soil erosion control appears to have been inadequately assessed and targeted. This study attempts to measure the benefit of soil erosion control received by residents in Palmerston North and surrounding areas. The research was undertaken by mail survey, using contingent valuation methods to elicit peoples' willingness to pay for the current level of soil erosion control and the willingness to pay for further increased levels of soil erosion control. The results showed that 54.6 % of respondents are aware of soil erosion effects in the area. The perceived benefits (as reflected in WTP) of the current level of soil erosion control varies from $204,321 to $1,393,666.95 per year whereas the benefit of having further increased levels of soil erosion control ranges between $320,083.07 - $1,020,998.63. In ascertaining the total value of soil erosion control, respondents took into account the preservation value, comprising bequest and existence value, in addition to use value and future use value.
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    The use of a geographic information system (GIS) for farm soil conservation planning : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Soil Science at Massey University
    (Massey University, 1993) Priyono, Cyprianus Nugroho Sulistyo
    The use of a Geographic Information Systems (PC ARC/INFO) for farm soil conservation planning was demonstrated in several neighbouring properties in the Apiti district, Manawatu. The area (775 ha) was mainly steep and strongly rolling hill country where the dominant land use was pastoral grazing by sheep and cattle. The main objective of this study was to utilize the GIS at each step of the farm soil conservation planning process. The planning process began with a land resources inventory (LRI) where information on basic physical resources relevant to land management and soil conservation was collected and stored in a database before further processing. Factors collected in the LRI included primary factors (soil type, soil depth, slope, rock type and elevation) and secondary factors (existing erosion, land use, fence lines and ownership, and drainage condition). A digital elevation model (DEM) was developed to display landforms. Field observations were also used and local farmers were given the opportunity to become involved in the planning process. The next step involved delineating areas of similar land use capability and potential land use. The areas were also assessed in terms of potential erosion and conservation needs. These operations were undertaken by combining the LRI factors in various ways. Results of these assessments were matched to define land units which have similar physical characteristics. Recommendations for management practices were then made by considering combinations of the factors. The plan was displayed as maps showing the management options available for farmers. Both map overlay procedures and database analyses were carried out at each step of the planning process. As the map overlay is a unique operation in the GIS, it was used to combine necessary factors from the LRI based on a set of criteria. Database analyses were then carried out using macro commands which were developed according to the criteria. The ability of the GIS for database analyses distinguishes the GIS from other systems whose primary objective is map production. The use of database analyses in this study was a particular example for making recommendations in soil conservation planning. However, the techniques are applicable to many different conditions and different purposes. The maps presented in this study are examples of how it is possible to show the results of analyses. Advantages and constraints of such procedures at each step of the planning process were discussed.
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    Sustainable land use on the East Coast : a case study of land use change in the Upper-Hikuwai catchment : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Development Studies at Massey University
    (Massey University, 1996) Zwart, Peter
    This thesis explores the principles of sustainability and applies them to the issue of land use on severely erosion-prone hill country in the East Coast region of the North Island of New Zealand. Sustainability is found to require a biophysical bottom line, implying a need for planning to establish threshold levels of protection for particular classes of land. The study uses a locally developed system of land classification which takes into account the physical causes and remedies of soil erosion as the basis for such a plan. This sets the biophysical bottom line to which land use and management must seek to conform, but above which, remain flexible, according to other societal objectives such as equity or efficiency. The history of land use change, and the policy response to the issue is reviewed for the region, and compared with this plan. The plan is then applied to one catchment subject to severe soil erosion, and where changes in land use are in process and the changes assessed and compared with the attitudes of the landowners and the context in which they have made their decisions. It was found that considerable progress had been made recently towards greater compliance with this plan and toward a pattern of land use more diverse and more consistent with the varying physical capacity of the area. This has been particularly facilitated by assistance from central and local government between 1988 and 1993. The study concludes, however, by highlighting the degree of favour shown to forestry interests over those of farming interests in current method of public support for erosion control. The study anticipates the eventual blanket afforestation of the catchment under this scheme.
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    The effect of poplar stand density on hill country pastures : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy (PhD), Massey University, Palmerston North, New Zealand
    (Massey University, 2006) Wall, Andrew James
    One-third of the North Island of New Zealand has been identified as requiring increased soil conservation if pastoral farming is to be sustainable. For over 50 years the planting of widely spaced poplar trees (Populus spp.) has been one of the main methods used to control soil erosion on hill pastures. Research has shown that these plantings have successfully decreased soil erosion but their impact on the productivity of pastoral farming has received little research attention. The research that has been undertaken has found poplars can suppress understorey pasture production by up to 40%, suggesting that farmers require more research information on the impact of planting conservation trees on the productivity of their farm if the use of conservation trees is to be more widely adopted on erosion prone land. The objective of this thesis was to provide comprehensive data on the relationship between the range of poplar densities used for soil conservation on the light and soil under poplars, and consequently the effect on understorey pastures. Three field sites on commercial sheep and beef hill farms, in regions with contrasting summer soil moisture availability, Manawatu (one site) and Central Hawke's Bay (two sites), were monitored for two years. Tree stocking rates ranged from 0 to 375 trees/ha. Measurements were based on units of four trees with most measurements either directly below the tree crowns or in the gaps between the trees, but more intensive transect measurements were also made. Photosynthetically active radiation (PAR) and the ratio of red to far red light (R:FR) were measured under the trees and in open pasture controls. Stand density indices used included all the commonly used measures of tree canopies, including digital photography, and stem diameter at breast height (DBH). PAR transmission was inversely related to all of the stand density indices with canopy closure based on digital photographs being the most robust of the indices used. PAR under the trees, relative to open pasture, was greater in the gaps than below tree crowns. Under a completely closed canopy, PAR transmission was reduced to 15-20% and 50-55% of the open pasture in summer and winter, respectively. The RFR under the trees, relative to open pasture, decreased markedly at high stand densities (allowing less than 40% PAR transmission) in summer, but was similar in winter. The change in PAR under the trees was shown to be a major factor limiting pasture growth, particularly directly below the tree crowns. For both summer and winter, canopy closure measured with a standard digital camera was strongly related to stand level PAR transmission (r2=0.88-0.97; P<0.0001) and was also a practical method of measuring canopy closure in the field. The soil measurements confirmed earlier research that soil pH increases under mature poplar trees. There was a 0.2 - 0.7 unit increase in soil pH in the upper 75 mm of soil over both contrasting regions. The soil fertility under the trees in terms of requirements for pasture growth was similar to that of the open pasture with calcium and potassium up to 2.2 and 9.0 quick test units higher in the soil under the trees than in the open pasture, respectively. The direct cause of the increased concentration of some cations under the trees was the annual tree leaf litter. Overall, the soil fertility under the trees had the potential to produce similar pasture production to that of the open pasture with the added advantage of less acid conditions. Averaged over all sites the respective annual net herbage accumulation (ANHA) under poplar canopy closures of 25, 50 and 75 % was estimated from the equations developed to be 77, 60 and 48% of the open pasture. The greatest decrease was directly below the tree crowns where at canopy closures greater than 20% the ANHA was a relatively constant 50% of open pasture. In the vertically projected gap between trees the ANHA decreased by 6.6% relative to open pasture for each 10% increase in canopy closure. At approximately 80% canopy closure there was no difference between the ANHA directly below the trees and in the gap. Pasture net herbage accumulation (NHA) under the trees relative to open pasture was at its lowest in summer and autumn (36% of open pasture under a closed canopy), and at its greatest in early spring before tree canopy leafed out (72% of open pasture under a closed canopy). The botanical composition and feed value of the pasture under the trees was broadly similar to that of the open pasture. The greatest impact of the poplars on the pasture was decreased NHA due to shading. The decrease in NHA directly below mature unpruned poplars is substantial and would decrease farm profitability if the poplar stand density were high over a large area of the farm. The use of poplars for soil conservation is essential but these results show the importance of managing trees through pruning and thinning so that canopy closure is minimised. ANHA under the trees can be maintained at 75% of the open pasture if canopy closure is prevented from exceeding 30-40%.
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    Environmental effects of densely planted willow and poplar in a silvopastoral system : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy (Ph. D.) in Agroforestry, Institute of Natural Resources, Massey University, Palmerston North, New Zealand
    (Massey University, 2007) Hussain, Zaker
    New Zealand, having large areas of hilly landscapes, is subject to the risk of soil erosion, and summer and autumn droughts that limit pasture growth, which in turn affects the livestock-based economy. The nitrogen and phosphorus input in fertilisers coupled with livestock excreta and soil disturbance impose a serious threat to downstream water quality. The planting of trees is one option used to decrease soil erosion, increase the quantity of forage and manage runoff. To date, research has mainly focused on wide spaced poplar trees for feed quality and their effects on understorey pasture growth. However, there is increasing interest in the use of densely planted willow and poplar for fodder purpose. The effects of young (< 5 yrs old) willow and poplar planted at close spacing on runoff, soil erosion, growth of understory pasture and nutrient losses have never been studied in New Zealand. Three field trials (two at Crop and Research Unit, Moginie, Manawatu and one at Riverside Farm, Masterton) were conducted between October 2004 and November 2006 that incorporated comparative establishment and growth of densely planted willow and poplar and their effects on soil moisture, runoff, sediment load and nutrient losses from grazed and fertilised farmland. It was concluded that densely planted willow and poplar (3-4 yrs) reduced total nitrogen (TN) and dissolved reactive phosphorus (DRP) by 47 % each and sediment load by 52 %. Young trees reduced surface runoff and soil moisture more as they aged. However, due to their deciduous nature willow and poplar were not effective in reducing surface runoff in winter and early spring. Sheep preferred camping under trees, especially in late spring and summer, and this led to greater deposition of dung and urine under trees than open pasture. Sheep grazing, especially in winter, significantly increased sediment and nutrient loads in runoff water. The N and P fertiliser application increased nutrient load in runoff water well above the threshold level required to initiate algal growth to create eutrophication. Densely planted willow and poplar significantly reduced understorey pasture growth by 23 % and 9 %, respectively, in their second year at Moginie, mainly due to shade, but coupled with soil moisture deficit in summer. The pasture growth in a willow browse block was 52 % of that in open pasture as a result of shade and differences in pasture species composition. Sheep browsing reduced willow leaf area significantly. Willow and poplar survival rates were similar (P > 0.05) after two years of establishment (100 % vs 90.5 %, respectively). However, willow grew faster than poplar in height (1.90 vs 1.35 m), stem diameter (43.5 vs 32.6 mm), canopy diameter (69 vs 34 cm) and number of shoots (8.7 vs 2.3) at the age of two years, respectively. The research clearly demonstrated that densely planted young willow and poplar trees can reduce runoff, sediment load and nutrient losses from farmland to freshwater, but shade and soil moisture can limit pasture growth under trees. It is recommended that willow and poplar should be planted at wide spacing on the whole farm to minimise loss of pasture. Where blocks of trees are necessary, such as willow browse blocks, sheep browsing can be used as a tool to reduce shade to improve pasture growth. Livestock access to riparian strips should be minimal to avoid livestock camping that can have deleterious effects on water quality.