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Analyzing Field-Derived Arboreal Spectral Signatures

Journal of Geographic Information System 2016年第2期8卷 193-204页

作者： Samuel G. Jenkins Peter Oduor Larry Kotchman Michael Kangas moorhead public service Moorhead MN USA Department of Geosciences North Dakota State University Fargo ND USA North Dakota Forest service Bottineau ND USA North Dakota State University Fargo ND USA

Orbital platforms spectral sensitivity can be a major limitation in ascertaining detailed identification and mapping of arboreal ecosystems. Field-derived spectral signatures using a narrow-band sensor, for example, ASD (Analytical Spectral Devices, Boulder, CO, USA) FieldSpec® Pro cover a spectral FR (Full Range) of 350 - 2500 nm exceeding spectral sensitivities of commonly used orbital platforms. The plausibility of deriving a spectral library of trees or forests within a training set is venerable. On the other hand, diagnostic spectral features between tree species or types are inherently difficult to ascertain from orbital platforms. This is so especially when the spectral library is applied to a demarcated region beyond the extents of training set. Basic suborbital limitations in detailed identification of trees and forests are presented in this study. We draw attention to spectral or temporal deficiencies and offer probable solutions depending on preferred or optimal spectral sensitivities. For example, Hyperion with 220 bands (400 - 2500 nm), one of the three primary instruments on the EO-1 spacecraft, has narrow bandwidths and covers the entire range of the spectral profiles collected for North Dakota tree species. With a 30 m spatial resolution, it is still useful in species identification in moderate stands of forest. Hyperion is a tasking satellite with limited passes over North Dakota (≈7% of total area) limiting its use as a platform of choice for statewide forest resource mapping.

关键词： Spectral Angle Spectral Correlation Matrix Leaf Reflectance

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A Cohort Model for Ash Mortality Risk Due to Potential Emerald Ash Borer Infestation

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Open Journal of Biophysics 2016年第2期6卷 38-51页

作者： Samuel G. Jenkins Peter G. Oduor Larry Kotchman Michael Kangas GIS Coordinator Moorhead Public Service Moorhead MN USA Department of Geosciences North Dakota State University Fargo ND USA State Forester North Dakota Forest Service Bottineau ND USA Nursery & State Forest Team Leader North Dakota State University Fargo ND USA

Emerald ash borer (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae) is a phloem-feeding beetle native to Asia that is causing widespread mortality of ash trees in eastern North America. In this study, we quantify ash mortality risk associated with potential anthropogenic-induced introduction of Emerald Ash Borer (EAB) in North Dakota. The cohort model is calibrated with data from Ohio using weighting across factors—proximity to existing ash stands, campgrounds, roads and rails—to get a more accurate assessment of overall ash mortality risk. These factors are known to be associated with introduction of EAB to unaffected areas. Two protocols, a) “detection trees” and b) EAB traps are utilized to investigate EAB presence. Ash mortality risk maps such as the ones produced here may guide the placement of traps. Although North Dakota regions of high density ash tree stands are few, the resulting relative ash mortality risk map displays: a) very high risk areas around the Turtle Mountains and Theodore Roosevelt National Park and b) regions of high relative risk along the main riparian corridors. The applicability of risk maps such as the one developed may aid in assessing areas that may require significant monitoring.

关键词： Exposure Pathway Relative Risk EAB Risk Model

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Exceedance Probability of the Standardized Precipitation-Evapotranspiration Index in the Texas High Plains

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Agricultural Sciences 2017年第8期8卷 783-800页

作者： Jerry E. moorhead Gary W. Marek Prasanna H. Gowda Thomas H. Marek Dana O. Porter Vijay P. Singh David K. Brauer Conservation and Production Research Laboratory USDA-ARS Bushland TX USA Grazinglands Research Laboratory USDA-ARS El Reno OK USA Department of Biological and Agricultural Engineering Texas A&M AgriLife Research Amarillo TX USA Department of Biological and Agricultural Engineering Texas A&M AgriLife Research and Extension Service Lubbock TX USA Department of Biological and Agricultural Engineering Texas A&M University College Station TX USA

Drought is a common occurrence in many arid and semi-arid regions that can have large negative impacts on water resources and agricultural production. Since agricultural drought is affected by both water supply and demand (precipitation and evapotranspiration), it is beneficial to include both in agricultural drought monitoring. The Standardized Precipitation-Evapotranspiration Index (SPEI) was found to be a suitable drought index for monitoring agricultural drought. In this study, the SPEI calculated from agro-meteorological weather stations was used to determine exceedance probabilities at five levels in the Texas High Plains. In addition, the kriging method was used to interpolate between the stations to generate spatial maps for the exceedance probabilities. No significant differences were found between stations, indicating any station should be suitable to represent the Texas High Plains. Results showed drought conditions occurred at all five probability levels during the summer growing season for this region. Although differences were not significantly different, the interpolated maps showed a trend where minor differences in the SPEI values were associated with the West-East precipitation gradient. However, there was no trend associated with the North-South air temperature gradient. A risk analysis showed that the SPEI probability values can provide policy and decision makers with additional information for better water management in the Texas High Plains.

关键词： Drought Semi-Arid Region Water Management Irrigation

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