103,387 research outputs found
Towards spatial assessment of carbon sequestration in peatlands: spectroscopy based estimation of fractional cover of three plant functional types
No full textPeatlands accumulated large carbon (C) stocks as peat in historical times. Currently however, many peatlands are on the verge of becoming sources with their C sequestration function becoming sensitive to environmental changes such as increases in temperature, decreasing water table and enhanced nitrogen deposition. Long term changes in vegetation composition are both, a consequence and indicator of future changes in C sequestration. Spatial continuous accurate assessment of the vegetation composition is a current challenge in keeping a close watch on peatland vegetation changes. In this study we quantified the fractional cover of three major plant functional types (PFTs; Sphagnum mosses, graminoids, and ericoid shrubs) in peatlands, using field spectroscopy reflectance measurements (400–2400 nm) on 25 plots differing in PFT cover. The data was validated using point intercept methodology on the same plots. Our results showed that the detection of open Sphagnum versus Sphagnum covered by vascular plants (shrubs and graminoids) is feasible with an R2 of 0.81. On the other hand, the partitioning of the vascular plant fraction into shrubs and graminoids revealed lower correlations of R2 of 0.54 and 0.57, respectively. This study was based on a dataset where the reflectance of all main PFTs and their pure components within the peatland was measured at local spatial scales. Spectrally measured species or plant community abundances can further be used to bridge scaling gaps up to canopy scale, ultimately allowing upscaling of the C balance of peatlands to the ecosystem level
Recent activities in the hyperspectral imaging network (Hyper-I-Net): A European consortium fostering imaging spectroscopy research
No full textDie Arktis unter Druck Menschgemachter Wandel in der Arktis und die Rolle der Schweiz
No full textDie Arktis leidet besonders stark unter dem Klimawandel und der Umweltverschmutzung. Während das arktische «Tauwetter» die Lebensgrundlagen der indigenen Bevölkerung gefährdet, sehen die Industrieländer darin eine Chance für neue wirtschaftliche Aktivitäten. Die Veränderungen in der Arktis wirken sich aber auch global aus. Deshalb ist eine Bewahrung der arktischen Öko- und Klimasysteme für die nachhaltige Entwicklung ausserhalb der Arktis essenziell – auch in der Schweiz.Fischer H, Chanteloup L, Csonka Y, Holm P, Jaccard S, Schaepman-Strub G, Schmale J, Vieli A (2022) Die Arktis unter Druck. Menschgemachter Wandel in der Arktis und die Rolle der Schweiz. Swiss Academies Reports 17 (4
Scaling spectroscopic approaches – from leaf albedo to ecosystems mapping
No full textField based spectroscopy for ecological and environmental monitoring has become an indispensable part of complete observational systems as defined in GEOSS (Global Earth Observation System of Systems). Spectral scaling approaches are currently ranging from molecular to ecosystem or even biome scales. We discuss the use of field spectroscopy in relation to supporting large-scale ecosystem and ecotone inventorying, in particular the retrieval of biochemical and structural attributes of vegetation. First, attention will be put on using an object-relational database for the structured compilation of field spectral measurements and corresponding metadata. Spectral libraries have been collected over a wide variety of natural and man-made targets and their sampling scheme is discussed. Second, recent advances in reflectance and radiance terminology for field spectrometers are discussed, propagating the use of spectral albedo. Advanced measurement instrumentation and facilities are presented that complement solar reflective measurements with the angular, thermal and plant fluorescence domains. Further, experiments measuring leaf albedo, transmittance and absorbtance are discussed using examples from a wide range of ecosystems and their ecotones. Finally, we discuss scaling approaches from field measurements to airborne and spaceborne mapping methods, demonstrating the wide use of field spectrometers for environmental applications. We conclude on the importance of using field spectrometers over the past one and a half decades at our institutions
Peatlands and the Carbon Cycle: From Local Processes to Global Implications
No full textFirst International Symposium on Carbon in Peatlands, Wageningen, Netherlands, 15-18 April 2007 Boreal and subarctic peatlands cover about 3% of the Earth's land surface and store 15-30% of the world's soil carbon (200-400 petagrams) as peat. This large C pool, in addition to C in Arctic soils, lies at higher latitudes that are experiencing ongoing climate change. Tropical peatlands also contain large C reservoirs, the stability of which is threatened by ongoing land use change. In response to a call from PeatNet (a National Science Foundation-supported research coordination network), Juul Limpens and Gabriela Schaepman-Strub proposed a small workshop on peatland C cycling, an idea that morphed into a meeting with 180 participants from 18 countries
A new lab facility for measuring bidirectional reflectance/emittance distribution functions of soils and canopies
No full textRecently, a laboratory measurement facility has been realized for assessing the anisotropic reflectance and emittance behaviour of soils, leaves and small canopies under controlled illumination conditions. The facility consists of an ASD FieldSpec 3 spectroradiometer covering the spectral range from 350 – 2500 nm at 1 nm spectral sampling interval. The spectroradiometer is deployed using a fiber optic cable with either a 1°, 8° or 25° instantaneous field of view (IFOV). These measurements can be used to assess the plant pigment (chlorophyll, xanthophyll, etc.) and non-pigment system (water, cellulose, lignin, nitrogen, etc.). The thermal emittance is measured using a NEC TH9100 Infrared Thermal Imager. It operates in a single band covering the spectral range from 8 – 14 mm with a resolution of 0.02 K. Images are 320 (H) by 240 (V) pixels with an IFOV of 1.2 mrad. A 1000 W Quartz Tungsten Halogen (QTH) lamp is used as illumination source, approximating the radiance distribution of the sun. This one is put at a fixed position during a measurement session. Multi-angular measurements are achieved by using a robotic positioning system allowing to perform either reflectance or emittance measurements over almost a complete hemisphere. The hemisphere can be sampled continuously between 0° and 80° from nadir and up to a few degrees from the hot-spot configuration (depending on the IFOV of the measurement device) for a backscattering target. Measurement distance to targets can be varied between 0.25 and 1 m, although with a distance of more than 0.6 m it is not possible to cover the full hemisphere. The goal is to infer the BRDF (bidirectional reflectance distribution function) and BTDF (bidirectional thermal distribution function) from these multi-angular measurements for various surface types (like soils, agricultural crops, small tree canopies and artificial objects) and surface roughness. The steering of the robotic arm and the reading of the spectroradiometer and the thermal camera are all fully automated
SiberianCrane_FrontiersInConservationScience
No full textCode and data for Increasing Arctic tundra flooding threatens wildlife habitat and survival: impacts on the critically endangered Siberian crane. This is for the paper,
Haverkamp, PJ, Bysykatova-Harmey, I, Germogenov, N, and Schaepman-Strub, G. 2022. Increasing Arctic tundra flooding threatens wildlife habitat and survival: impacts on the critically endangered Siberian crane. Frontiers in Conservation Science. https://doi.org/10.3389/fcosc.2022.79999
Climate of Minnesota Part III: Temperature and Its Application
No full textBaker, Donald G.; Strub, Joseph H. Jr.. (1965). Climate of Minnesota Part III: Temperature and Its Application. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/108239
Climate of Minnesota
No full text40 pagesPart I. Probability of Occurrence in the Spring and Fall of Selected Low TemperaturesBaker, Donald G.; Strub, Joseph H. Jr.. (1963). Climate of Minnesota. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/139557
Climate of Minnesota: Part II. The Agricultural and Minimum-Temperature-Free Seasons
No full text31 pagesBaker, Donald G.; Strub, Joseph H. Jr.. (1963). Climate of Minnesota: Part II. The Agricultural and Minimum-Temperature-Free Seasons. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/140009
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