Mitigation translocation for conservation of New Zealand skinks

<p>Worldwide, human development is leading to the expansion and intensification of land use, with increasing encroachment on natural habitats. A rising awareness of the deleterious effects of habitat destruction on species and ecosystems has increased the use of strategies intended to mitigate these negative impacts. One increasingly common strategy is mitigation translocation, the movement of living organisms from a future development site to another location in an effort to mitigate damage caused. Mitigation translocations may be implemented due to legislation or regulations in many jurisdictions, and in many instances command more resources than purely conservation-motivated translocations. Although they are intended to reduce or offset harm, the effectiveness of mitigation translocations as a conservation strategy has been questioned. I investigated the effectiveness of mitigation translocations for achieving conservation outcomes, using the study system of endemic New Zealand skinks. New Zealand’s skinks show a high level of endemism, are threatened by habitat loss and predation by introduced mammals, and are increasingly subject to mitigation translocations, making them an ideal study system for investigating mitigation outcomes. I investigated: whether mitigation translocations are meeting conservation goals; how the implementation and legal requirements of mitigation translocation relate to conservation goals; and how mitigation translocation practices might be improved to achieve better conservation outcomes. A technique used in mitigation translocations of lizards in New Zealand is the construction of rock piles as habitat enhancement at the receiving site. I developed a novel use of computer game physics software to model the three-dimensional interstitial spaces within such rock piles, and used this model to design rock piles with the aim of protecting translocated skinks from mice (Mus musculus), New Zealand’s smallest introduced mammalian predator. The protection is achieved by selecting rocks to optimise the size of interstitial spaces to be accessible to skinks but not to the larger mice (or other larger predators). This rock pile design could be used to improve survival of skinks both in translocations and other situations such as backyard conservation or restoration. The modelling technique I developed could be used for investigation of refuge space more widely, for instance in other terrestrial systems or aquatic systems. I also took part in a mitigation translocation of lizards at Transmission Gully near Wellington, New Zealand. I used this translocation to test my rock pile design, and as a case study of the challenges facing mitigation translocations and the barriers to conservation success. In addition, I revisited nine historical mitigation translocations of skinks (7–14 years post translocation), took surveys of current populations to assess their success at meeting conservation goals, and found a success rate of 22%, considerably lower than conservation translocations of New Zealand skinks (success rate of 88.9%). Despite this, all but one met their goals of fulfilling legislative requirements. Mitigation translocations fail to result in conservation benefit due to their implementation and goals. The goals of mitigation translocations are rooted in legislation, and vary due to inconsistent application of relevant laws (in New Zealand, the Wildlife Act 1953 and the Resource Management Act 1991), and the fact that the requirements under these laws do not necessarily reflect conservation goals. Additionally, mitigation translocations may be undertaken even when evidence indicates that meaningful conservation outcomes are unlikely (as in the case of the translocation at Transmission Gully). Failure may also be due to poor implementation; examples from case studies here include failure to control predators, low standards of planting at receptor sites, and small founder populations. To improve conservation outcomes, legal requirements for mitigation translocations should be implemented to require biologically-relevant goals (including a no net loss of biodiversity standard) and management techniques, and alternative methods of meeting conservation goals should be considered where appropriate.</p>

Mitigation translocation for conservation of New Zealand skinks

<p>Worldwide, human development is leading to the expansion and intensification of land use, with increasing encroachment on natural habitats. A rising awareness of the deleterious effects of habitat destruction on species and ecosystems has increased the use of strategies intended to mitigate these negative impacts. One increasingly common strategy is mitigation translocation, the movement of living organisms from a future development site to another location in an effort to mitigate damage caused. Mitigation translocations may be implemented due to legislation or regulations in many jurisdictions, and in many instances command more resources than purely conservation-motivated translocations. Although they are intended to reduce or offset harm, the effectiveness of mitigation translocations as a conservation strategy has been questioned. I investigated the effectiveness of mitigation translocations for achieving conservation outcomes, using the study system of endemic New Zealand skinks. New Zealand’s skinks show a high level of endemism, are threatened by habitat loss and predation by introduced mammals, and are increasingly subject to mitigation translocations, making them an ideal study system for investigating mitigation outcomes. I investigated: whether mitigation translocations are meeting conservation goals; how the implementation and legal requirements of mitigation translocation relate to conservation goals; and how mitigation translocation practices might be improved to achieve better conservation outcomes. A technique used in mitigation translocations of lizards in New Zealand is the construction of rock piles as habitat enhancement at the receiving site. I developed a novel use of computer game physics software to model the three-dimensional interstitial spaces within such rock piles, and used this model to design rock piles with the aim of protecting translocated skinks from mice (Mus musculus), New Zealand’s smallest introduced mammalian predator. The protection is achieved by selecting rocks to optimise the size of interstitial spaces to be accessible to skinks but not to the larger mice (or other larger predators). This rock pile design could be used to improve survival of skinks both in translocations and other situations such as backyard conservation or restoration. The modelling technique I developed could be used for investigation of refuge space more widely, for instance in other terrestrial systems or aquatic systems. I also took part in a mitigation translocation of lizards at Transmission Gully near Wellington, New Zealand. I used this translocation to test my rock pile design, and as a case study of the challenges facing mitigation translocations and the barriers to conservation success. In addition, I revisited nine historical mitigation translocations of skinks (7–14 years post translocation), took surveys of current populations to assess their success at meeting conservation goals, and found a success rate of 22%, considerably lower than conservation translocations of New Zealand skinks (success rate of 88.9%). Despite this, all but one met their goals of fulfilling legislative requirements. Mitigation translocations fail to result in conservation benefit due to their implementation and goals. The goals of mitigation translocations are rooted in legislation, and vary due to inconsistent application of relevant laws (in New Zealand, the Wildlife Act 1953 and the Resource Management Act 1991), and the fact that the requirements under these laws do not necessarily reflect conservation goals. Additionally, mitigation translocations may be undertaken even when evidence indicates that meaningful conservation outcomes are unlikely (as in the case of the translocation at Transmission Gully). Failure may also be due to poor implementation; examples from case studies here include failure to control predators, low standards of planting at receptor sites, and small founder populations. To improve conservation outcomes, legal requirements for mitigation translocations should be implemented to require biologically-relevant goals (including a no net loss of biodiversity standard) and management techniques, and alternative methods of meeting conservation goals should be considered where appropriate.</p>

Autonomous Loading System for Load-Haul-Dump (LHD) Machines Used in Underground Mining

This paper describes an autonomous loading system for load-haul-dump (LHD) machines used in underground mining. The loading of fragmented rocks from draw points is a complex task due to many factors including: bucket-rock interaction forces that are difficult to model, humidity that increases cohesion forces, and the possible presence of boulders. The proposed system is designed to integrate all the relevant tasks required for ore loading: rock pile identification, LHD positioning in front of the ore pile, charging and excavating into the ore pile, pull back and payload weighing. The system follows the shared autonomy paradigm: given that the loading process may not be completed autonomously in some cases, it takes into account that the machine/agent can detect this situation and ask a human operator for assistance. The most novel component of the proposed autonomous loading system is the excavation algorithm, and the disclosure of the results obtained from its application in a real underground production environment. The excavation method is based on the way that human operators excavate: while excavating, the bucket is tilted intermittently in order to penetrate the material, and the boom of the LHD is lifted on demand to prevent or correct wheel skidding. Wheel skidding is detected with a patented method that uses LIDAR-based odometry and internal measurements of the LHD. While a complete loading system was designed, the validation had to be divided in two stages. One stage included the rock pile identification and positioning, and the other included the charging, excavation, pull back, and weighting processes. The stage concerning the excavation algorithm was validated using full-scale experiments with a real-size LHD in an underground copper mine in the north of Chile, while the stage concerning the rock pile identification was later validated using real data. The tests showed that the excavation algorithm is able to load the material with an average of 90% bucket fill factor using between three and four attempts (professional human operators required between two and three loading attempts in this mine).

Thermal-Hydrological-Chemical Modeling of a Covered Waste Rock Pile in a Permafrost Region

In order to reduce contaminant mass loadings, thermal cover systems may be incorporated in the design of waste rock piles located in regions of continuous permafrost. In this study, reactive transport modeling was used to improve the understanding of coupled thermo-hydrological and chemical processes controlling the evolution of a covered waste rock pile located in Northern Canada. Material properties from previous field and laboratory tests were incorporated into the model to constrain the simulations. Good agreement between simulated and observational temperature data indicates that the model is capable of capturing the coupled thermo-hydrological processes occurring within the pile. Simulations were also useful for forecasting the pile’s long-term evolution with an emphasis on water flow and heat transport mechanisms, but also including geochemical weathering processes and sulfate mass loadings as an indicator for the release of contaminated drainage. An uncertainty analysis was carried out to address different scenarios of the cover’s performance as a function of the applied infiltration rate, accounting for the impacts of evaporation, runoff, and snow ablation. The model results indicate that the cover performance is insensitive to the magnitude of recharge rates, except for limited changes of the flow regime in the shallow active layer. The model was expanded by performing an additional sensitivity analysis to assess the role of cover thicknesses. The simulated results reveal that a cover design with an appropriate thickness can effectively minimize mass loadings in drainage by maintaining the active layer completely within the cover.

Mapping Potentially Acid Generating Material on Abandoned Mine Lands Using Remotely Piloted Aerial Systems

Weathering and transport of potentially acid generating material (PAGM) at abandoned mines can degrade downstream environments and contaminate water resources. Monitoring the thousands of abandoned mine lands (AMLs) for exposed PAGM using field surveys is time intensive. Here, we explore the use of Remotely Piloted Aerial Systems (RPASs) as a complementary remote sensing platform to map the spatial and temporal changes of PAGM across a mine waste rock pile on an AML. We focus on testing the ability of established supervised and unsupervised classification algorithms to map PAGM on imagery with very high spatial resolution, but low spectral sampling. At the Perry Canyon, NV, USA AML, we carried out six flights over a 29-month period, using a RPAS equipped with a 5-band multispectral sensor measuring in the visible to near infrared (400–1000 nm). We built six different 3 cm resolution orthorectified reflectance maps, and our tests using supervised and unsupervised classifications revealed benefits to each approach. Supervised classification schemes allowed accurate mapping of classes that lacked published spectral libraries, such as acid mine drainage (AMD) and efflorescent mineral salts (EMS). The unsupervised method produced similar maps of PAGM, as compared to supervised schemes, but with little user input. Our classified multi-temporal maps, validated with multiple field and lab-based methods, revealed persistent and slowly growing ‘hotspots’ of jarosite on the mine waste rock pile, whereas EMS exhibit more rapid fluctuations in extent. The mapping methods we detail for a RPAS carrying a broadband multispectral sensor can be applied extensively to AMLs. Our methods show promise to increase the spatial and temporal coverage of accurate maps critical for environmental monitoring and reclamation efforts over AMLs.