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Item Quantifying the performance of silvopastoralism for landslide erosion and sediment control in New Zealand’s hill country : a dissertation presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Physical Geography at Massey University, Palmerston North, New Zealand(Massey University, 2022) Spiekermann, RaphaelLandslide erosion results in loss of productive soils and pasture. Moreover, sediment delivered to streams from landslides can contribute to the degradation of freshwater and marine receiving environments by smothering benthic habitats and increasing turbidity, light attenuation, and sediment-bound contaminants. Silvopastoralism is an important land management practice used to combat landslide erosion and improve the health of downstream aquatic ecosystems. Yet, the effectiveness of widely spaced trees in reducing shallow landslide erosion and sediment delivery at hillslope to catchment scales remains largely unknown. Previous studies have been limited by scale (e.g., hillslope) or method (e.g., univariate analyses). This research aims to develop spatially explicit modelling to assess the impact of differing tree species, planting densities, and individual tree location, on rainfall-triggered landslides and sediment delivery while accounting for varying environmental conditions, such as slope gradient, lithology, or soil type. As such, this thesis combines geospatial methods and statistical models to address key challenges related to erosion and sediment control in New Zealand’s pastoral hill country. First, using a study area in the Wairarapa, located in the southeast of the North Island, New Zealand (840 km2), a method was developed using open-source remote sensing products to generate high-resolution individual tree influence models for the dominant tree species. The objective was to generate a spatial explicit representation of individual trees for landscape-scaled statistical slope stability modelling. The combined hydrological and mechanical influence of trees on slopes was inferred through the spatial relationship between trees and landslide erosion. These spatial distribution models for individual trees of different vegetation types represent the average contribution to slope stability as a function of distance from tree at 1-m spatial resolution. The normalised models (0-1) largely agree with the shape and distribution of force from existing physical root reinforcement models. Of exotic tree species that were planted for erosion and sediment control, poplars (Populus spp.) and willows (Salix spp.) make up 51% (109,000) of trees located on hillslopes at a mean density of 3 trees/ha. In line with previous studies, poplars and willows have the greatest contribution to slope stability with an average maximum effective distance of 20 m. Yet, native kānuka (Kunzea spp.) is the most abundant woody vegetation species on hillslopes within the study area, with an average of 24 trees/ha, providing an important soil conservation function. A large proportion (56% or 212.5 km2) of erosion-prone terrain in the study area remains untreated. In a world-first, this allowed the influence of individual trees to be included in a statistical landslide susceptibility model using binary logistic regression to quantify the effectiveness of silvopastoral systems at reducing landslide erosion and to support targeted erosion mitigation. Models were trained and tested using a landslide inventory consisting of 43,000 landslide scars mapped across the study area. Model performance was very good, with a median Area Under the Receiver Operating Characteristic curve (AUROC) of 0.95 in the final model used for predictions, which equates to an accuracy of 88.7% using a cut-off of 0.5. The effect of highly skewed continuous tree influence models on the maximum likelihood estimator was tested using different sampling strategies aimed at reducing positive skewness. With an adequate sample size, highly skewed continuous predictor variables do not result in an inflation of effect size. Application of the landslide susceptibility model was illustrated using two farms from within the study area (Site 1: 1,700-ha; Site 2: 462-ha) by quantifying the reduction in shallow landslide erosion due to trees. Compared to a pasture only baseline, landslide erosion was reduced by 17% at Site 1 and 43% at Site 2 due to all existing vegetation. The effectiveness of individual trees in reducing landslide erosion was shown to be less a function of species than that of targeting highly susceptible areas with adequate plant densities. The excellent model performance means spatial predictions are precise, which has implications for land management as the maps provide greater certainty and spatial refinement to inform landslide mitigation. The terrain occupied by the “high” susceptible class – defined as the terrain where 80% of mapped landslides were triggered in the past – occupies only 12% of Site 1 and 7% of Site 2. This suggests there is great potential for improved targeting of erosion mitigation to these areas of the farms where landsliding may be expected in the future. To enable biological mitigation to be targeted to critical source areas of sediment, determinants of sediment connectivity were investigated for a landslide-triggering storm event in 1977. In a first of its kind, a morphometric landslide connectivity model was developed using lasso logistic regression to predict the likelihood of sediment delivery to streams following landslide initiation. An experiment was undertaken to explore a range of connectivity scenarios by defining a set of sinks and simulating varying rates of sediment generation during runoff events of increasing magnitude. Sediment delivery ratios for the 1977 event ranged from 0.21 to 0.29, equating to an event sediment yield of 3548 t km-2 to 9033 t km-2. The likelihood of sediment delivery was greatly enhanced where debris tails coalesce. Besides scar size variables, overland flow distance and vertical distance to sink were the most important morphometric predictors of connectivity. When scar size variables were removed from the connectivity model, median AUROC was reduced from 0.88 to 0.75. By coupling landslide susceptibility and connectivity predictions in a modular form, we quantified the cost effectiveness of targeted versus non-targeted approaches to shallow landslide mitigation. Targeted mitigation of landslide-derived sediment was found to be approximately an order of magnitude more cost-effective than a non-targeted approach. Compared with a pasture-only baseline, a 34% reduction in sediment delivery can be achieved by increasing slope stability through spaced tree planting on 6.5% of the pastoral land. In contrast, the maximum reduction achievable through comprehensive coverage of widely spaced planting is 56%. The coupled landslide susceptibility and connectivity predictions (maps) provide an objective basis to not only target mitigation to areas where future shallow landslides are likely to occur, but – perhaps more importantly – target future tree planting to locations that are likely to be future sources of fine sediment. In this way, the research presented in this thesis is both methodologically novel and has immediate application to support land management decisions aimed at creating a more sustainable socio-ecological landscape.Item The use of a geographic information system to investigate soil slip distribution and the land use capability classification in the East Coast region, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science in Soil Science at Massey University(Massey University, 1995) Hendriksen, Sheryl DeniseThe land of the North Island East Coast region has such a severe erosion problem that in some places the current land use cannot be sustained. The expansion of exotic forestry in the region will provide protection for the land, regional growth and development, and employment, but it also brings competition for good land. The New Zealand Resource Management Act, 1991, aims to promote sustainable use of our resources and requires regulatory authorities to monitor the state of their natural resources and to follow the principles set in the RMA when developing land use policies. Remotely sensed data provides a timely and accurate assessment of surface features. Aerial photography provides a better delineation of soil slip erosion than satellite imagery. Geographic Information Systems facilitate the storage and display of resource information. Through manipulation of GIS data layers, relationships between the distribution of soil slip erosion following Cyclone Bola, 1988, and other physical factors are investigated. The density of soil slip increases with increasing slope angle to a maximum on slopes of 30°. The amount of soil slip depends on the underlying rock type with jointed mudstone having the highest density. Most soil slip erosion occurs on NE, N, NW, and E facing slopes, but the reason for this cannot be attributed to either slope angle or rock type. The Land Use Capability classification is currently used by land use managers and planners to describe the land in terms of its limitation to productive uses. The detail of information in the New Zealand Land Resource Inventory LUC classification can be improved by incorporating more detailed slope angle and slope aspect information derived from digital contour data.Item Vehicle damage to vegetation of the Rangipo Desert, Tongariro National Park, National Park, New Zealand : a thesis presented in partial fulfillment of the requirements for the degree of MSc in Ecology, Massey University, Turitea, Palmerston North, New Zealand(Massey University, 2014) Smith, Angelina RobynRangipo Desert, Tongariro National Park, Central North Island, New Zealand, contains one of New Zealand’s unique habitats due to the desert-like environment containing cushions, low lying species, and native grasses which create a diverse mosaic of plant species and colour. This area is under anthropogenic threat from drivers operating vehicles over the vegetation. My aim was is investigate the damage to vegetation and substrates which have been driven over by vehicles. Aerial images were used to draw information about the Desert’s ecosystem, and driver’s manoeuvring preferences which were ground-truthed. A Canonical Correspondence Analysis was used to evaluate the accuracy of categories from the aerials after ground-truthing. A Paired t test was used to show varying vegetation densities against other tested variables. A Chi Square Analysis was used to examine where drivers preferred to drive. The results indicate drivers prefer to drive over bare substrate and sparsely vegetated areas within the desert, avoiding dense vegetation, deeply cut channels and rough, un-driveable terrain. The direct damage done by vehicles to vegetation and surrounding substrate was tested by running a simulated tyre over the substrate and plants. A plant having had a tyre pushed over it by hand was compared to a plant that had been previously damaged by vehicles, and a control (undamaged) plant. Analysis of Variance was used to test differences in the growth of the plants within each treatment and the change in topography. There is evidence of plant damage; however, different species reacted differently to treatments, depending on which variable was being tested, making it difficult to identify which species are most affected by vehicle damage. The tyres alter the substrate instantly. Intact and broken substrates were compared by creating wind and rain with a leaf blower and watering can. The change in substrate height was measured and Analysis of Variance was used to test the amount of substrate erosion. Results show broken substrates are eroded at a greater rate than intact substrates, and the erosion rate is increased when the substrate is dry. Wet, sandy substrates in windy conditions and wet, pumice substrates in rain have the lowest amount of substrate movement after damage. The Rangipo Desert’s dry and open ecosystem and vegetation is vulnerable to damage from vehicles. Vehicles cause plant die-back, increase erosion and have the potential to change the current ecosystem. Preventing vehicles driving into the Desert, and educating members of the public about ecosystem damage are good starting points to manage and preserve this area of Tongariro National Park. KEYWORDS Arid ecosystems, vehicle damage, erosion, plant changes, microtopography.Item Geology and its relationship to erosion in the Southern Ruahine Range, North Island, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science at Massey University, Palmerston North(Massey University, 1984) Marden, MichaelThe structure and lithology of a sequence of Mesozoic greywackes comprising the Torlesse terrane within the southern Ruahine Range has been mapped. At a scale of 1:25 000 the sequence was subdivided into informal lithozones with one or more lithozones constituting a higher order lithostratigraphic unit here referred to as a Lithotype. Each of three recognised Lithotypes occupies a consistent stratigraphic position throughout a 40 km long mapped area. From east to west the three Lithotypes are: (1) the Tamaki Lithotype; (2) the Wharite Lithotype; and (3) the Western Lithotype. The easternmost Tamaki Lithotype and the westernmost Western Lithotype consist of a relatively undeformed flysch-type sequence of distal turbidites. The centrally located wharite Lithotype structurally underlies the Tamaki Lithotype but overlies the Western Lithotype. It comprises a complex sequence of predominantly flysch-type sedimentary rocks, together with lithologically diverse, argillite-dominated, clast-bearing debris flow deposits; large sheet-like bodies of massive volcanics (and associated cherts) that have been emplaced by gravitational sliding; and intact pillow lava accumulations and horizons of red and green argillite of syndepositional origin. Major and trace element analyses of volcanic lithologies indicate that most samples were erupted in a mid-ocean ridge or intraplate setting. None appear to have been derived from an island arc setting. The bulk of the clastic sediments consist of reworked materials derived by the erosion of a mixed volcano-plutonic source and redeposited in a distal deep-water submarine fan environment. Blocks of allochthonous fossiliferous shallow-water lithologies indicate that the source terrane, in part, comprised rocks of Late Triassic age. Autochthonous fossils indicate that sedimentation continued until at least Late Jurassic time. Part of the stratigraphic sequence was severely deformed along a low angle thrust zone in Early Cretaceous time at the onset of the Rangitata Orogeny. An early phase of ductile deformation resulted in plastically and permanently deformed rocks. Ductile deformation is restricted to strata comprising the Wharite Lithotype which, with its allochthonous debris, in part, constitutes an olistostrome that has undergone tectonic deformation and hence also constitutes a melange. Thus it may be regarded as a tectonised olistostrome. Ductile deformation was succeeded by the development of shear fractures during subsequent phases of brittle deformation that affected strata comprising all three Lithotypes. Brittle deformation occurred in conjunction with episodes of faulting and folding during the second orogeny - the Kaikoura Orogeny in Pliocene to Recent times. Active faults that were initiated during the early phase of ductile deformation continued to be sites of active fault displacement throughout Quaternary and Holocene time. Late Quaternary tectonic features along these major active faults have been mapped. Minimum rates of vertical fault displacements since Ohakean time approximate 1 mm/yr in this area. Several phases of folding were recognised, including: (1) an early phase of syndepositional, highly asymmetric folds with well developed axial plane cleavage; and (2) three post-lithification phases of folding - e.g. (a) steeply plunging isoclinal folds; (b) subhorizontal, open asymmetric folds; and (c) steeply plunging open folds. Contacts between the three Lithotypes are not thought to be major tectonic breaks but are instead of primary depositional origin and have become sites of subsequent fault movement in Quaternary time. The three Lithotypes may therefore represent a near complete eastward dipping, westward younging overturned stratigraphic sequence. They are not fault-bound terranes. Metamorphism to prehnite pumpellyite grade, folding and rotation of the strata to its present steep attitude predates Late Cretaceous sedimentation. The westward rotation and imbrication of thrust sheets that are internally westward younging but form part of a regionally eastward younging succession of thrust sheets was the result of underthrusting at a convergent plate margin. The relationship between structural and lithological characteristics of the Torlesse bedrock and the magnitude of valley slope erosion in the southern Ruahine Range is investigated. Comparison of aerial photographs spanning a 28 year period between 1946 and 1974 indicate that erosion has increased by 91%. The greatest proportion of this eroded area occurs on the steeper north- and west-facing slopes. Saturation of colluvium during major storm events is the prime triggering mechanism for the majority of shallow translational slope movements. Debris slides and debris avalanches predominate and result from failure at less than 1m depth at the colluvium-bedrock contact. Rock slides are few in number and are structurally controlled, failing along bedding plane surfaces at greater than 1m depth. Rock falls and rock topples are least numerous and only involve small quantities of material. An erosion rate of 1215m3/ha/yr for the southern Ruahine Range is of the same order of magnitude as other New Zealand and overseas studies and although considered to be severe it is not unduly excessive. Much of the forest deterioration in this area is due to the opening of the canopy by the successive removal of large tracts of forest vegetation through mass movement processes during episodes of increased rainfall. Large-scale rotational and translational mass movement features including rock slumps, earth slumps, earth slides and ridge-top features (involving bedrock only), have been documented from 109 localities. A relationship between the incidence of rock slumps and major fault breccia zones has been established in this area. The majority of large-scale mass movement features failed in pre-historic time but two failed in historic time. The consequences of future mass movements upon lowland areas adjacent to the base of the Range is discussed. A map showing the relative stability of slopes and the predominant forms of slope movement most likely to occur under the present seismic, climatic, physiographic and human conditions is presentedItem Revegetation of recent soil slips in Manawatu : a thesis presented in partial fulfilment of the requirements for the degree of Master in Applied Science at Massey University(Massey University, 2009) Prasad, Kamal KishorTrifolium repens, Lotus pedunculatus and Holcus lanatus were oversown on two recent soil slip surfaces at AgResearch’s Ballantrae pastoral hill‐country farm near Woodville. The two slip surfaces were located on (Manamahu steepland soil) sedimentary mudstone. One slip had a north aspect and the other had a south aspect. Both slips were located on a land class 6 with slope 28‐330. The pasture species were oversown during early spring and the percentage seedling emergence and early establishment from viable seeds oversown was analysed at early spring (Day 15), late spring (Day 45), early summer (Day 90), and late summer (Day 120). The slip surfaces showed micro‐climatic extremes in terms of both soil moisture and surface temperatures during the summer period. Significant differences (P < 0.05) were found in soil moisture between north and south facing slip surfaces. Higher soil moisture and lower soil mean temperature were recorded on the south aspect slip surface. Significant differences (P < 0.05) were found between the three pasture species in terms of seedling emergence and early establishment. Significant differences (P < 0.05) were also found with aspect. The south aspect slip surface had a higher percentage of seedling emergence and earlier establishment for all the species. Interaction between species by aspect became significantly different (P < 0.05) at Day 90 and Day 120. The main effects of time and species were also significantly different (P < 0.05) illustrating seedling emergence and establishment as a race against time. Trifolium repens was a more successful pasture specie, than L. pedunculatus and H. lanatus due to its higher consistency on both north and south slip surfaces. Oversowing T. repens during early spring is a viable option for rehabilitation of recent soil slips in Manawatu.Item Mio/Pliocene phreatomagmatic volcanism in the Western Pannonian Basin(Massey University., 2004-01-01) Martin, Ulrike; Nemeth, KarolyNo abstract availableItem Large hydrovolcanic field in the Pannonian Basin: general characteristics of the Bakony- Balaton Highland Volcanic Field, Hungary.(Massey University., 1999-01-01) Nemeth, Karoly; Martin, UlrikeNo abstract availableItem Long-term erosion-rate calculation from the Waipiata Volcanic Field (New Zealand) based on erosion remnants of scoria cones, tuff rings and maars.(Massey University., 2001-01-01) Nemeth, KarolyErosion of scoria cones, tuff rings and maars follows a general evolution. Identification of distribution patterns of preserved pyroclastic lithofacies of scoria cones, tuff rings and maars allows an estimation of "depth" of erosion since volcanism ceased. Study of the accidental lithic clast population in pyroclastic rocks of erosion remnants of basaltic maar/tuff ring volcanoes of the Miocene Waipiata Volcanic Field (WVF), New Zealand is demonstrated to be a good tool re-establish the "missing" stratigraphy and estimate the erosion since volcanism. An example from a subsequently tilted erosion remnant of the Swinburn multivent volcanic complex (WVF) demonstrates the importance of tilting as an effect of erosion rate calculations. The 3 vents of the WVF investigated from New Zealand suggest a range of erosion rates from 3.75 to 46 m/My depending on 1) the position of the remnant in comparison to uplifted fault/fold blocks; and, 2) considering or neglecting the effect of subsequent tilting on erosion rate calculations.