Browsing by Subject "vegetation"

Now showing 1 - 5 of 5
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    Fire, vegetation, and Holocene climate in a southeastern Tibetan lake: a multi-biomarker reconstruction from Paru Co
    (EGU, 2018-10) Callegaro, Alice; Battistel, Dario; Kehrwald, Natalie M.; Matsubara Pereira, Felipe; Kirchgeorg, Torben; del Carmen Villoslada Hidalgo, Maria; Bird, Broxton W.; Barbante, Carlo; Earth Sciences, School of Science
    The fire history of the Tibetan Plateau over centennial to millennial timescales is not well known. Recent ice core studies reconstruct fire history over the past few decades but do not extend through the Holocene. Lacustrine sedimentary cores, however, can provide continuous records of local environmental change on millennial scales during the Holocene through the accumulation and preservation of specific organic molecular biomarkers. To reconstruct Holocene fire events and vegetation changes occurring on the southeastern Tibetan Plateau and the surrounding areas, we used a multi-proxy approach, investigating multiple biomarkers preserved in core sediment samples retrieved from Paru Co, a small lake located in the Nyainqentanglha Mountains (29∘47′45.6'' N, 92∘21′07.2'' E; 4845 m a.s.l.). Biomarkers include n-alkanes as indicators of vegetation, polycyclic aromatic hydrocarbons (PAHs) as combustion proxies, fecal sterols and stanols (FeSts) as indicators of the presence of humans or grazing animals, and finally monosaccharide anhydrides (MAs) as specific markers of vegetation burning processes. Insolation changes and the associated influence on the Indian summer monsoon (ISM) affect the vegetation distribution and fire types recorded in Paru Co throughout the Holocene. The early Holocene (10.7–7.5 cal kyr BP) n-alkane ratios demonstrate oscillations between grass and conifer communities, resulting in respective smouldering fires represented by levoglucosan peaks, and high-temperature fires represented by high-molecular-weight PAHs. Forest cover increases with a strengthened ISM, where coincident high levoglucosan to mannosan (L ∕ M) ratios are consistent with conifer burning. The decrease in the ISM at 4.2 cal kyr BP corresponds with the expansion of regional civilizations, although the lack of human FeSts above the method detection limits excludes local anthropogenic influence on fire and vegetation changes. The late Holocene is characterized by a relatively shallow lake surrounded by grassland, where all biomarkers other than PAHs display only minor variations. The sum of PAHs steadily increases throughout the late Holocene, suggesting a net increase in local to regional combustion that is separate from vegetation and climate change.
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    Preface "Water, climate, and vegetation: ecohydrology in a changing world"
    (2012-12) Wang, Lixin; Liu, J.; Sun, G.; Wei, X.; Liu, S.; Dong, Q.
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    Satellite Observed Positive Impacts of Fog on Vegetation
    (Wiley, 2020-06) Qiao, Na; Zhang, Lifu; Huang, Changping; Jiao, Wenzhe; Maggs-Kölling, Gillian; Marais, Eugene; Wang, Lixin; Earth Sciences, School of Science
    Fog is an important water source for many ecosystems, especially in drylands. Most fog‐vegetation studies focus on individual plant scale; the relationship between fog and vegetation function at larger spatial scales remains unclear. This hinders an accurate prediction of climate change impacts on dryland ecosystems. To this end, we examined the effect of fog on vegetation utilizing both optical and microwave remote sensing‐derived vegetation proxies and fog observations from two locations at Gobabeb and Marble Koppie within the fog‐dominated zone of the Namib Desert. Significantly positive relationships were found between fog and vegetation attributes from optical data at both locations. The positive relationship was also observed for microwave data at Gobabeb. Fog can explain about 10%–30% of variability in vegetation proxies. These findings suggested that fog impacts on vegetation can be quantitatively evaluated from space using remote sensing data, opening a new window for research on fog‐vegetation interactions.
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    A successful percutaneous mechanical vegetation debulking used as a bridge to surgery in acute tricuspid valve endocarditis
    (The Society for Thoracic Disease, 2016-01-29) Makdisi, George; Casciani, Thomas; Wozniak, Thomas C.; Roe, David W.; Hashmi, Zubair A.; Department of Radiology and Imaging Sciences, IU School of Medicine
    Timing of surgical management of acute infective endocarditis is a major challenge, with respect to surgical complications, risks of recurrences and optimal valve repair or replacement. We present a case of a 24-year-old male with a history of intravenous drug abuse, who was referred to our center after 10 days of medical management of acute infective endocarditis. Upon arrival he was in septic shock, multi-organ failure, and mobile vegetations on the tricuspid valve with severe tricuspid regurgitation. He also had bilateral pulmonary infarcts and an ischemic stroke in the right parietal lobe. A successful percutaneous transcatheter mechanical vegetation debulking was performed followed by surgical valve replacement seven days later. This case introduces a new option in the management of right-sided endocarditis in critically ill patient, and demonstrates the technical feasibility of a debulking procedure in this setting, which led subsequently to a significant improvement in patient’s condition, and he was ultimately able to undergo definitive surgery.
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    Thermal remote sensing for plant ecology from leaf to globe
    (Wiley, 2022-09) Farella, Martha M.; Fisher, Joshua B.; Jiao, Wenzhe; Key, Kesondra B.; Barnes, Mallory L.; School of Public and Environmental Affairs
    1. Surface temperatures are mechanistically linked to vegetation biophysical and physiological processes. Although remote sensing in the thermal infrared (TIR) domain can offer novel insights into the impacts of changing surface temperatures on vegetation, the transformative potential of remote sensing for plant ecology has not yet been realized. 2. Remotely sensed surface temperatures can be used to derive stomatal behaviour and identify stressful environmental conditions in near-real time. Plant species, traits and structural characteristics can be evaluated with high spectral resolution TIR emissivity. 3. Beyond canopy scales, thermal remote sensing can enhance the inferences obtained from manipulative experiments and empirical evidence, providing unique insight into shifts in species ranges and phenology with changing climate conditions. 4. Scaling leaf traits, canopy structure and regional patterns require an integrated understanding of both process and technology. Theory linking surface temperatures to vegetation dynamics is summarized from an energy balance perspective. We outline scaling considerations including the impacts of morphology on leaf energy balance, canopy structure influences on convective heat exchange and potential confounding impacts of non-vegetated surfaces. 5. Synthesis. We introduce a unifying framework to link leaf to globe through thermal remote sensing. Recent and emerging advances in sensors, data availability and analytics, together with synergies between TIR remote sensing and other data sources, present a timely opportunity for ecologists to advance our understanding of plant physiology, ecology and biogeography with thermal remote sensing.