John Dymond - Academia.edu (original) (raw)
Papers by John Dymond
New Zealand Science Review, Aug 21, 2022
IGARSS 2020 - 2020 IEEE International Geoscience and Remote Sensing Symposium, 2020
Research in New Zealand indicates that winter forage grazing on steep land creates a high risk of... more Research in New Zealand indicates that winter forage grazing on steep land creates a high risk of sediment loss. This loss can have a significant impact on sediment and associated nutrient content of waterways. A national-scale map of winter forage cropping on land with slope of greater than 7° was created using spectral and temporal analysis of Sentinel-2 imagery. Images between March and September 2018 were masked for cloud, cloud shadow, and snow using a time-series-controlled layer. Land cover classification using maximum likelihood estimation was applied. Field boundaries were generated using the temporal image stack so that field-level homogeneity could be exploited. The mode classification per-polygon and bare ground observation dates allowed polygons totaling 0.69% of New Zealand's agricultural hill country to be stratified into three certainty levels of risky agricultural practice. For the first time, extent and spatial distribution of these practices have been estimated for policy development.
Sustainable forest conservation and management practices require highly resolved and accurate map... more Sustainable forest conservation and management practices require highly resolved and accurate maps of forest types. Extrapolation of field data, however, cannot achieve the necessary level of detail. The joint use of space-based optical imagery and structural information from synthetic aperture radar (SAR) and canopy metrics derived from air-borne Light Detection and Ranging (LiDAR) facilitates detailed classification of forest types. We present a segmentation-based support vector machine (SVM) classification using data from ESA's Sentinel-1 and 2 missions, ALOS PALSAR and airborne LiDAR to create a map of structural types within indigenous forest in Greater Wellington, New Zealand. The model is evaluated using k-fold cross-validation with up-scaled field data. The highest classification accuracy of 80.9% is achieved for bands 2, 3, 4, 5, 8, 11, and 12 from Sentinel-2, the ratio of bands VH and VV from Sentinel-1, HH from PALSAR, and mean canopy height and 97th percentile canopy...
Journal of Environmental Management, 2022
Removing vegetation cover from hill-slope land increases risk for soil erosion and delivery of se... more Removing vegetation cover from hill-slope land increases risk for soil erosion and delivery of sediment to waterways. In New Zealand's productive landscapes, clear-fell harvesting of forestry blocks and winter forage grazing by agricultural livestock are two significant causes of vegetation removal. Bare ground exposed by these activities varies annually and seasonally in location and spatial extent. Modelling soil erosion therefore requires temporally and spatially explicit mapping of this bare ground. We have developed an automated mapping method using time-series satellite imagery, thereby enabling wide-area coverage and ease of updating. The temporal analysis identifies land use along with the period of vegetation removal. It produces results per land parcel (in vector format) for use in a Geographic Information System. We present a description of our method, national maps and statistics of bare ground extent in New Zealand's hill-country forestry and winter forage grazing land in 2018, and an assessment of accuracy. The attributes of the mapped land parcels are designed for input into a soil erosion estimation model such as the New Zealand Universal Soil Loss Equation.
Remote Sensing, 2020
Repeat frequencies of optical remote sensing satellites have been increasing over the last 40 yea... more Repeat frequencies of optical remote sensing satellites have been increasing over the last 40 years, but there is still dependence on clear skies to acquire usable imagery. To increase the quality of data, composited mosaics of satellite imagery can be used. In this paper, we develop an automated method for clearing clouds and producing different types of composited mosaics suitable for use in cloud-affected countries, such as New Zealand. We improve the Tmask algorithm for cloud detection by using a parallax method to produce an initial cloud layer and by using an object-based cloud and shadow approach to remove false cloud detections. We develop several parametric scoring approaches for choosing best-pixel composites with minimal remaining cloud. The automated mosaicking approach produced Sentinel-2 mosaics of New Zealand for five successive summers, 2015/16 through 2019/20, with remaining cloud being less than 0.1%. Contributing satellite overpasses were typically of the order of...
New Zealand Journal of Agricultural Research, 2020
The evaluation of heavy metal concentrations in five pepper samples sold along Papa-Abeokuta high... more The evaluation of heavy metal concentrations in five pepper samples sold along Papa-Abeokuta highways, Ogun State, South West Nigeria was investigated in this present work using standard methods. The heavy metals viz. Lead (Pb), Cadmium (Cd), Manganese (Mn), Copper (Cu), Mercury (Hg) and Zinc (Zn) were determined using Atomic Absorption Spectrophometry Method. The results of the analysis showed that lead (Pb) ranged from 0.02mg/100g to 0.07mg/100g; Cadmium varied from 0.00mg/100g to 0.01mg/100g; while Manganese (Mn) ranged from 0.02mg/100g to 0.05mg/100g; The level of copper (Cu) as shown by the result are; 0.31mg/100g; 0.57mg/100g; 0.60mg/100g; 0.43mg/100g and 0.73mg/100g respectively for all the five pepper samples. Mercury, though in negligible amount has highest concentration of 0.01mg/100g while Zinc (Zn) varied from 0.50mg/100g to 0.70mg/100g. The results generally revealed that level of contamination by these heavy metals on the pepper samples were very low when compared to the permissible limits stipulated by FAO/WHO (2003).
Remote Sensing, 2020
New Zealand kauri trees are threatened by the kauri dieback disease (Phytophthora agathidicida (P... more New Zealand kauri trees are threatened by the kauri dieback disease (Phytophthora agathidicida (PA)). In this study, we investigate the use of pan-sharpened WorldView-2 (WV2) satellite and Light Detection and Ranging (LiDAR) data for detecting stress symptoms in the canopy of kauri trees. A total of 1089 reference crowns were located in the Waitakere Ranges west of Auckland and assessed by fieldwork and the interpretation of aerial images. Canopy stress symptoms were graded based on five basic stress levels and further refined for the first symptom stages. The crown polygons were manually edited on a LiDAR crown height model. Crowns with a mean diameter smaller than 4 m caused most outliers with the 1.8 m pixel size of the WV2 multispectral bands, especially at the more advanced stress levels of dying and dead trees. The exclusion of crowns with a diameter smaller than 4 m increased the correlation in an object-based random forest regression from 0.85 to 0.89 with only WV2 attribute...
Piantadosi, J., Anderssen, R.S. and Boland J. (eds) MODSIM2013, 20th International Congress on Modelling and Simulation, Dec 1, 2013
New Zealand Plant Protection, 2007
The spatial change of woody vegetation in the Canterbury region was automatically mapped between ... more The spatial change of woody vegetation in the Canterbury region was automatically mapped between 1990 and 2001 using Landsat satellite image mosaics The intersection of valid data from these mosaics gave coverage of 84 of the Canterbury region Changes in woody cover greater than 5 ha were identified Of the 5 ha areas of woody change only those that were likely to have been a scrub change were selected using ancillary thematic data for current vegetation cover (eg afforestation and deforestation were excluded) This resulted in 2466 polygons of potential scrub change These polygons were rapidly checked by visual assessment of the satellite imagery and assigned to exotic or indigenous scrub change categories Between 1990 and 2001 the total scrub weed area in the Canterbury region increased by 3600 400 ha and indigenous scrub increased by 2300 400 ha
Remote Sensing, 2019
Image classification and interpretation are greatly aided through the use of image segmentation. ... more Image classification and interpretation are greatly aided through the use of image segmentation. Within the field of environmental remote sensing, image segmentation aims to identify regions of unique or dominant ground cover from their attributes such as spectral signature, texture and context. However, many approaches are not scalable for national mapping programmes due to limits in the size of images that can be processed. Therefore, we present a scalable segmentation algorithm, which is seeded using k-means and provides support for a minimum mapping unit through an innovative iterative elimination process. The algorithm has also been demonstrated for the segmentation of time series datasets capturing both the intra-image variation and change regions. The quality of the segmentation results was assessed by comparison with reference segments along with statistics on the inter- and intra-segment spectral variation. The technique is computationally scalable and is being actively use...
New Zealand Journal of Marine and Freshwater Research, 2019
Riverbank erosion is an important component of catchment sediment budget models but remains one o... more Riverbank erosion is an important component of catchment sediment budget models but remains one of the least wellunderstood processes, particularly at large spatial scales. Here, we develop and test a new bank migration model in New Zealand for large catchment applications that (1) better represents spatial variability in factors influencing bank erosion and (2) improves predictive performance. We represent bank migration rates as a function of reach-scale stream power, channel sinuosity, soil texture, valley confinement, riparian woody vegetation and channel protection works. The new model significantly improves prediction compared to the SedNetNZ model. Comparison of measured bank migration rates with individual variables shows percent silt + clay derived from soil maps exhibited the strongest correlation, whereas other variables were non-significant. The model results demonstrate that improved prediction can be achieved by combining spatial representation of multiple factors over large areas, despite low correlation between individual variables and bank migration rates.
New Zealand Journal of Ecology, 2017
Four iterations of the New Zealand Land Cover Database have been produced from satellite imagery ... more Four iterations of the New Zealand Land Cover Database have been produced from satellite imagery for nominal dates of 1996/97, 2001/02, 2008/09 and 2012/13. These data may be used to estimate changes in area for land cover classes of interest. However, these estimates are subject to uncertainty, which can be significant, particularly when change in area is small. Changes in indigenous vegetation classes are of interest for a number of applications, including monitoring threatened environments. Here we show how the combination of exhaustive sampling of change polygons with random 'truth' sampling can be used to estimate the uncertainty of area change. We demonstrate the method on five important indigenous covers: indigenous forest, broadleaved indigenous hardwoods, manuka and/or kanuka, tall tussock grassland, and subalpine shrubland. For these classes, we estimate their area in 2008/09 and the change of area between 2001/2002 and 2008/09. Areas were estimated to within plus or minus 5%. Change in areas were estimated to within plus or minus 10% of change for classes with a large change in area, and to within plus or minus 30% for the classes with a small change in area. We anticipate similar uncertainties for estimated changes in area between the other dates and for other classes. The number of random 'truth' samples required for this assessment was very high, in excess of 30 000. Many more samples would be required to further lower the uncertainties.
Remote Sensing Letters, 2014
Biodiversity Loss in a Changing Planet, 2011
Introduction 1.1 Biodiversity and habitat provision in New Zealand The Millennium Ecosystem Asses... more Introduction 1.1 Biodiversity and habitat provision in New Zealand The Millennium Ecosystem Assessment (MEA) found that over the past 50 years, natural ecosystems have changed more rapidly and extensively than in any other period of human history (Millennium Ecosystem Assessment, 2005). In the 30 years after 1950, more land was converted to cropland than in the 150 years between 1700 and 1850, and now one quarter of the earth's surface is under cultivation. In the last decades of the twentieth century, approximately 20% of the world's coral reefs have disappeared and an additional 20% show serious degradation. Of the fourteen major biomes in the world, two have lost two thirds of their area to agriculture and four have lost one half of their area to agriculture. The distribution of species has become more homogeneous, primarily as a result of species introduction associated with increased travel and shipping. Over the past few hundred years, the species extinction rate has increased by a thousand times, with some 10-30% of mammal, bird, and amphibian species threatened with extinction. Genetic diversity has declined globally, particularly among cultivated species. A framework of ecosystem services was developed to examine how these changes influence human well-being, including supporting, regulating, provisioning, and cultural services (Millennium Ecosystem Assessment, 2003). While overall there has been a net gain in human well-being and economic development, it has come at the cost of degradation to many ecosystem services and consequent diminished ecosystem benefits for future generations. Many ecosystem services are degrading because they are simply not considered in natural resource management decisions. Biodiversity plays a major role in human wellbeing and the provision of ecosystem services (Diaz et al., 2006). For example, natural ecosystems provide humans with clean air and water, play a major role in the decomposition of wastes and recycling of nutrients, maintain soil quality, aid pollination, regulate local climate and reduce flooding. New Zealand has been identified as a biodiversity hotspot (Conservation International, 2010). Located in the Pacific Ocean, south east of Australia, New Zealand covers 270 thousand square kilometres on three main islands (North, South and Stewart Island). It has a wide variety of landscapes, with rugged mountains, rolling hills, and wide alluvial plains. Over 75 percent of New Zealand is above 200 meters in altitude, reaching a maximum of www.intechopen.com Biodiversity Loss in a Changing Planet 202 3,700 meters on Mount Cook. Climate is highly variable and has played a key role in biodiversity distribution (Leathwick et al., 2003). As New Zealand has been an isolated land for more than 80 million years, the level of endemism is very high, with more than 90% of insects, 85% of vascular plants, and a quarter of birds found only in New Zealand (Ministry for the Environment, 2007). One of the most notable characteristics of New Zealand's biodiversity is the absence of terrestrial mammals, apart from two bat species, and the dominance of slow-growing evergreen forest. New Zealand's indigenous biodiversity is not only unique within a global context-it is also of major cultural importance to the indigenous Maori people. Maori have traditionally relied on, and used, a range of ecosystem services including native flora and fauna for food, weaving, housing, and medicines. The isolation of New Zealand has preserved its unique biodiversity, but also rendered the biodiversity vulnerable to later invasion. When Maori migrated from the Pacific Islands, circa 700 years ago, predation upon birds began and much lowland indigenous forest was cleared, especially in the South Island. Rats and dogs were also introduced. The birds, having evolved in an environment free of predators, were susceptible to disturbance and many began to decline to the edge of extinction. When Europeans arrived in the early 19th century, they extensively modified the landscape and natural habitats. Large tracts of land were cleared and converted into productive land for pastoral agriculture, cropping, horticulture, roads, and settlements. Only the steepest mountain land and hill country was left in indigenous forest and shrubland. Swamps were drained and tussock grasslands were burned. Not only was the natural habitat significantly altered, but a large range of exotic species were introduced, including deer, possums, stoats, ferrets, and weasels, causing a rapid decline in native birds and degrading native forest. Other introduced plants and animals have had significant effects in the tussock grasslands and alpine shrublands, most notably rabbits, deer, and pigs, and the spread of wilding pines, gorse, broom, and hieracium. Despite significant efforts to control weeds and pests and halt the loss of natural habitat, around 3,000 species are now considered threatened, including about 300 animals, and 900 vascular plants (Hitchmough et al., 2005). The Economics of Ecosystems and Biodiversity study (TEEB) suggested that it is difficult to manage what is not measured (TEEB, 2010). To prevent further biodiversity loss, decisionmakers need accurate information to assess and monitor biodiversity. However, biodiversity assessment is not a trivial task. As defined by the Convention on Biological Diversity (CBD), biodiversity encompasses "the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems" (CBD, 1992). Conceptually, biodiversity is a nested hierarchy comprising genes, species, populations, and ecosystems. In order to assess status and trend, these multiple levels need to be assessed simultaneously. Noss (1990) suggested a conceptual framework with indicators providing measurable surrogates for the different levels of organisation. Loss of extent is one of the many indicators in this framework, and it has been widely used internationally in reporting to the CBD (Lee et al., 2005). It is relatively easy to report, and has been recognised as one of the main drivers for biodiversity loss (Department of Conservation [DOC] and Ministry for the Environment [MFE], 2000). 1.2 Previous assessments in natural habitat Several national surveys of vegetation cover have been completed. The New Zealand Land Resource Inventory was derived by stereo photo-interpretation of aerial photographs
Soil Erosion Issues in Agriculture, 2011
Natural Hazards and Earth System Sciences, 2008
New Zealand Science Review, Aug 21, 2022
IGARSS 2020 - 2020 IEEE International Geoscience and Remote Sensing Symposium, 2020
Research in New Zealand indicates that winter forage grazing on steep land creates a high risk of... more Research in New Zealand indicates that winter forage grazing on steep land creates a high risk of sediment loss. This loss can have a significant impact on sediment and associated nutrient content of waterways. A national-scale map of winter forage cropping on land with slope of greater than 7° was created using spectral and temporal analysis of Sentinel-2 imagery. Images between March and September 2018 were masked for cloud, cloud shadow, and snow using a time-series-controlled layer. Land cover classification using maximum likelihood estimation was applied. Field boundaries were generated using the temporal image stack so that field-level homogeneity could be exploited. The mode classification per-polygon and bare ground observation dates allowed polygons totaling 0.69% of New Zealand's agricultural hill country to be stratified into three certainty levels of risky agricultural practice. For the first time, extent and spatial distribution of these practices have been estimated for policy development.
Sustainable forest conservation and management practices require highly resolved and accurate map... more Sustainable forest conservation and management practices require highly resolved and accurate maps of forest types. Extrapolation of field data, however, cannot achieve the necessary level of detail. The joint use of space-based optical imagery and structural information from synthetic aperture radar (SAR) and canopy metrics derived from air-borne Light Detection and Ranging (LiDAR) facilitates detailed classification of forest types. We present a segmentation-based support vector machine (SVM) classification using data from ESA's Sentinel-1 and 2 missions, ALOS PALSAR and airborne LiDAR to create a map of structural types within indigenous forest in Greater Wellington, New Zealand. The model is evaluated using k-fold cross-validation with up-scaled field data. The highest classification accuracy of 80.9% is achieved for bands 2, 3, 4, 5, 8, 11, and 12 from Sentinel-2, the ratio of bands VH and VV from Sentinel-1, HH from PALSAR, and mean canopy height and 97th percentile canopy...
Journal of Environmental Management, 2022
Removing vegetation cover from hill-slope land increases risk for soil erosion and delivery of se... more Removing vegetation cover from hill-slope land increases risk for soil erosion and delivery of sediment to waterways. In New Zealand's productive landscapes, clear-fell harvesting of forestry blocks and winter forage grazing by agricultural livestock are two significant causes of vegetation removal. Bare ground exposed by these activities varies annually and seasonally in location and spatial extent. Modelling soil erosion therefore requires temporally and spatially explicit mapping of this bare ground. We have developed an automated mapping method using time-series satellite imagery, thereby enabling wide-area coverage and ease of updating. The temporal analysis identifies land use along with the period of vegetation removal. It produces results per land parcel (in vector format) for use in a Geographic Information System. We present a description of our method, national maps and statistics of bare ground extent in New Zealand's hill-country forestry and winter forage grazing land in 2018, and an assessment of accuracy. The attributes of the mapped land parcels are designed for input into a soil erosion estimation model such as the New Zealand Universal Soil Loss Equation.
Remote Sensing, 2020
Repeat frequencies of optical remote sensing satellites have been increasing over the last 40 yea... more Repeat frequencies of optical remote sensing satellites have been increasing over the last 40 years, but there is still dependence on clear skies to acquire usable imagery. To increase the quality of data, composited mosaics of satellite imagery can be used. In this paper, we develop an automated method for clearing clouds and producing different types of composited mosaics suitable for use in cloud-affected countries, such as New Zealand. We improve the Tmask algorithm for cloud detection by using a parallax method to produce an initial cloud layer and by using an object-based cloud and shadow approach to remove false cloud detections. We develop several parametric scoring approaches for choosing best-pixel composites with minimal remaining cloud. The automated mosaicking approach produced Sentinel-2 mosaics of New Zealand for five successive summers, 2015/16 through 2019/20, with remaining cloud being less than 0.1%. Contributing satellite overpasses were typically of the order of...
New Zealand Journal of Agricultural Research, 2020
The evaluation of heavy metal concentrations in five pepper samples sold along Papa-Abeokuta high... more The evaluation of heavy metal concentrations in five pepper samples sold along Papa-Abeokuta highways, Ogun State, South West Nigeria was investigated in this present work using standard methods. The heavy metals viz. Lead (Pb), Cadmium (Cd), Manganese (Mn), Copper (Cu), Mercury (Hg) and Zinc (Zn) were determined using Atomic Absorption Spectrophometry Method. The results of the analysis showed that lead (Pb) ranged from 0.02mg/100g to 0.07mg/100g; Cadmium varied from 0.00mg/100g to 0.01mg/100g; while Manganese (Mn) ranged from 0.02mg/100g to 0.05mg/100g; The level of copper (Cu) as shown by the result are; 0.31mg/100g; 0.57mg/100g; 0.60mg/100g; 0.43mg/100g and 0.73mg/100g respectively for all the five pepper samples. Mercury, though in negligible amount has highest concentration of 0.01mg/100g while Zinc (Zn) varied from 0.50mg/100g to 0.70mg/100g. The results generally revealed that level of contamination by these heavy metals on the pepper samples were very low when compared to the permissible limits stipulated by FAO/WHO (2003).
Remote Sensing, 2020
New Zealand kauri trees are threatened by the kauri dieback disease (Phytophthora agathidicida (P... more New Zealand kauri trees are threatened by the kauri dieback disease (Phytophthora agathidicida (PA)). In this study, we investigate the use of pan-sharpened WorldView-2 (WV2) satellite and Light Detection and Ranging (LiDAR) data for detecting stress symptoms in the canopy of kauri trees. A total of 1089 reference crowns were located in the Waitakere Ranges west of Auckland and assessed by fieldwork and the interpretation of aerial images. Canopy stress symptoms were graded based on five basic stress levels and further refined for the first symptom stages. The crown polygons were manually edited on a LiDAR crown height model. Crowns with a mean diameter smaller than 4 m caused most outliers with the 1.8 m pixel size of the WV2 multispectral bands, especially at the more advanced stress levels of dying and dead trees. The exclusion of crowns with a diameter smaller than 4 m increased the correlation in an object-based random forest regression from 0.85 to 0.89 with only WV2 attribute...
Piantadosi, J., Anderssen, R.S. and Boland J. (eds) MODSIM2013, 20th International Congress on Modelling and Simulation, Dec 1, 2013
New Zealand Plant Protection, 2007
The spatial change of woody vegetation in the Canterbury region was automatically mapped between ... more The spatial change of woody vegetation in the Canterbury region was automatically mapped between 1990 and 2001 using Landsat satellite image mosaics The intersection of valid data from these mosaics gave coverage of 84 of the Canterbury region Changes in woody cover greater than 5 ha were identified Of the 5 ha areas of woody change only those that were likely to have been a scrub change were selected using ancillary thematic data for current vegetation cover (eg afforestation and deforestation were excluded) This resulted in 2466 polygons of potential scrub change These polygons were rapidly checked by visual assessment of the satellite imagery and assigned to exotic or indigenous scrub change categories Between 1990 and 2001 the total scrub weed area in the Canterbury region increased by 3600 400 ha and indigenous scrub increased by 2300 400 ha
Remote Sensing, 2019
Image classification and interpretation are greatly aided through the use of image segmentation. ... more Image classification and interpretation are greatly aided through the use of image segmentation. Within the field of environmental remote sensing, image segmentation aims to identify regions of unique or dominant ground cover from their attributes such as spectral signature, texture and context. However, many approaches are not scalable for national mapping programmes due to limits in the size of images that can be processed. Therefore, we present a scalable segmentation algorithm, which is seeded using k-means and provides support for a minimum mapping unit through an innovative iterative elimination process. The algorithm has also been demonstrated for the segmentation of time series datasets capturing both the intra-image variation and change regions. The quality of the segmentation results was assessed by comparison with reference segments along with statistics on the inter- and intra-segment spectral variation. The technique is computationally scalable and is being actively use...
New Zealand Journal of Marine and Freshwater Research, 2019
Riverbank erosion is an important component of catchment sediment budget models but remains one o... more Riverbank erosion is an important component of catchment sediment budget models but remains one of the least wellunderstood processes, particularly at large spatial scales. Here, we develop and test a new bank migration model in New Zealand for large catchment applications that (1) better represents spatial variability in factors influencing bank erosion and (2) improves predictive performance. We represent bank migration rates as a function of reach-scale stream power, channel sinuosity, soil texture, valley confinement, riparian woody vegetation and channel protection works. The new model significantly improves prediction compared to the SedNetNZ model. Comparison of measured bank migration rates with individual variables shows percent silt + clay derived from soil maps exhibited the strongest correlation, whereas other variables were non-significant. The model results demonstrate that improved prediction can be achieved by combining spatial representation of multiple factors over large areas, despite low correlation between individual variables and bank migration rates.
New Zealand Journal of Ecology, 2017
Four iterations of the New Zealand Land Cover Database have been produced from satellite imagery ... more Four iterations of the New Zealand Land Cover Database have been produced from satellite imagery for nominal dates of 1996/97, 2001/02, 2008/09 and 2012/13. These data may be used to estimate changes in area for land cover classes of interest. However, these estimates are subject to uncertainty, which can be significant, particularly when change in area is small. Changes in indigenous vegetation classes are of interest for a number of applications, including monitoring threatened environments. Here we show how the combination of exhaustive sampling of change polygons with random 'truth' sampling can be used to estimate the uncertainty of area change. We demonstrate the method on five important indigenous covers: indigenous forest, broadleaved indigenous hardwoods, manuka and/or kanuka, tall tussock grassland, and subalpine shrubland. For these classes, we estimate their area in 2008/09 and the change of area between 2001/2002 and 2008/09. Areas were estimated to within plus or minus 5%. Change in areas were estimated to within plus or minus 10% of change for classes with a large change in area, and to within plus or minus 30% for the classes with a small change in area. We anticipate similar uncertainties for estimated changes in area between the other dates and for other classes. The number of random 'truth' samples required for this assessment was very high, in excess of 30 000. Many more samples would be required to further lower the uncertainties.
Remote Sensing Letters, 2014
Biodiversity Loss in a Changing Planet, 2011
Introduction 1.1 Biodiversity and habitat provision in New Zealand The Millennium Ecosystem Asses... more Introduction 1.1 Biodiversity and habitat provision in New Zealand The Millennium Ecosystem Assessment (MEA) found that over the past 50 years, natural ecosystems have changed more rapidly and extensively than in any other period of human history (Millennium Ecosystem Assessment, 2005). In the 30 years after 1950, more land was converted to cropland than in the 150 years between 1700 and 1850, and now one quarter of the earth's surface is under cultivation. In the last decades of the twentieth century, approximately 20% of the world's coral reefs have disappeared and an additional 20% show serious degradation. Of the fourteen major biomes in the world, two have lost two thirds of their area to agriculture and four have lost one half of their area to agriculture. The distribution of species has become more homogeneous, primarily as a result of species introduction associated with increased travel and shipping. Over the past few hundred years, the species extinction rate has increased by a thousand times, with some 10-30% of mammal, bird, and amphibian species threatened with extinction. Genetic diversity has declined globally, particularly among cultivated species. A framework of ecosystem services was developed to examine how these changes influence human well-being, including supporting, regulating, provisioning, and cultural services (Millennium Ecosystem Assessment, 2003). While overall there has been a net gain in human well-being and economic development, it has come at the cost of degradation to many ecosystem services and consequent diminished ecosystem benefits for future generations. Many ecosystem services are degrading because they are simply not considered in natural resource management decisions. Biodiversity plays a major role in human wellbeing and the provision of ecosystem services (Diaz et al., 2006). For example, natural ecosystems provide humans with clean air and water, play a major role in the decomposition of wastes and recycling of nutrients, maintain soil quality, aid pollination, regulate local climate and reduce flooding. New Zealand has been identified as a biodiversity hotspot (Conservation International, 2010). Located in the Pacific Ocean, south east of Australia, New Zealand covers 270 thousand square kilometres on three main islands (North, South and Stewart Island). It has a wide variety of landscapes, with rugged mountains, rolling hills, and wide alluvial plains. Over 75 percent of New Zealand is above 200 meters in altitude, reaching a maximum of www.intechopen.com Biodiversity Loss in a Changing Planet 202 3,700 meters on Mount Cook. Climate is highly variable and has played a key role in biodiversity distribution (Leathwick et al., 2003). As New Zealand has been an isolated land for more than 80 million years, the level of endemism is very high, with more than 90% of insects, 85% of vascular plants, and a quarter of birds found only in New Zealand (Ministry for the Environment, 2007). One of the most notable characteristics of New Zealand's biodiversity is the absence of terrestrial mammals, apart from two bat species, and the dominance of slow-growing evergreen forest. New Zealand's indigenous biodiversity is not only unique within a global context-it is also of major cultural importance to the indigenous Maori people. Maori have traditionally relied on, and used, a range of ecosystem services including native flora and fauna for food, weaving, housing, and medicines. The isolation of New Zealand has preserved its unique biodiversity, but also rendered the biodiversity vulnerable to later invasion. When Maori migrated from the Pacific Islands, circa 700 years ago, predation upon birds began and much lowland indigenous forest was cleared, especially in the South Island. Rats and dogs were also introduced. The birds, having evolved in an environment free of predators, were susceptible to disturbance and many began to decline to the edge of extinction. When Europeans arrived in the early 19th century, they extensively modified the landscape and natural habitats. Large tracts of land were cleared and converted into productive land for pastoral agriculture, cropping, horticulture, roads, and settlements. Only the steepest mountain land and hill country was left in indigenous forest and shrubland. Swamps were drained and tussock grasslands were burned. Not only was the natural habitat significantly altered, but a large range of exotic species were introduced, including deer, possums, stoats, ferrets, and weasels, causing a rapid decline in native birds and degrading native forest. Other introduced plants and animals have had significant effects in the tussock grasslands and alpine shrublands, most notably rabbits, deer, and pigs, and the spread of wilding pines, gorse, broom, and hieracium. Despite significant efforts to control weeds and pests and halt the loss of natural habitat, around 3,000 species are now considered threatened, including about 300 animals, and 900 vascular plants (Hitchmough et al., 2005). The Economics of Ecosystems and Biodiversity study (TEEB) suggested that it is difficult to manage what is not measured (TEEB, 2010). To prevent further biodiversity loss, decisionmakers need accurate information to assess and monitor biodiversity. However, biodiversity assessment is not a trivial task. As defined by the Convention on Biological Diversity (CBD), biodiversity encompasses "the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems" (CBD, 1992). Conceptually, biodiversity is a nested hierarchy comprising genes, species, populations, and ecosystems. In order to assess status and trend, these multiple levels need to be assessed simultaneously. Noss (1990) suggested a conceptual framework with indicators providing measurable surrogates for the different levels of organisation. Loss of extent is one of the many indicators in this framework, and it has been widely used internationally in reporting to the CBD (Lee et al., 2005). It is relatively easy to report, and has been recognised as one of the main drivers for biodiversity loss (Department of Conservation [DOC] and Ministry for the Environment [MFE], 2000). 1.2 Previous assessments in natural habitat Several national surveys of vegetation cover have been completed. The New Zealand Land Resource Inventory was derived by stereo photo-interpretation of aerial photographs
Soil Erosion Issues in Agriculture, 2011
Natural Hazards and Earth System Sciences, 2008