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Natural geological, chronic and acute release of volcanic gases can have a dramatic impact on
vegetative ecosystems and potential impact on regional agriculture and human health. This research incorporates a series of observations using leaf level gas exchange, chlorophyll fluorescence and remotely sensed reflectance measurements of vegetation expe...
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Context 1
... first data point (elevation = 1939 m) plotted in Figure 4 represents the control site with no detectable SO 2 , and highest NDVI values. The second data point (elevation = 2594 m) represents minimal SO 2 stress (SO 2 = 0.053 ppm) with NDVI values dropping from the previous site (Table 4). The third data point (elevation = 2673) repre- sents extreme SO 2 induced stress (SO 2 = 0.1823 ppm) with moderate CO 2 buffering (CO 2 = 460 ppm) and dra- matic drops in NDVI values. ...
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Citations
... Volcanic activity can also negatively affect or kill plants, which decreases the NDVI of the area. Sulfur-bearing gas emissions, extremely high CO 2 concentrations, and/or increases in soil temperature can kill large areas of plants (Farrar et al., 1995;Jenkins et al., 2012). All three of these phenomena are typically associated with hydrothermal activity or shallow magma, whereas CO 2 emissions without accompanying sulfur gases or major soil temperature anomalies are usually indicative of the degassing of deeper pockets of magma (Symonds et al., 2001). ...
... The hydrothermal area slowly expanded from 2000 until 2005, then started expanding more rapidly for the next 10 years before stabilizing at ∼33,300 m 2 around 2015 (Vaughan et al., 2020). This expansion was primarily identified by measuring the size of the tree kill zone, which is likely caused by some combination of excessive heat in the soil, sulfur gasses, or excessively high CO 2 concentrations in the soil (Farrar et al., 1995;Jenkins et al., 2012;Vaughan et al., 2020). Infrared camera images showed an arc-shaped zone of high temperatures above 50°C; but outside this zone, the soil temperatures generally return to ambient levels within a few meters (Vaughan et al., 2020). ...
Volcanic volatile emissions provide information about volcanic unrest but are difficult to detect with satellites. Volcanic degassing affects plants by elevating local CO2 and H2O concentrations, which may increase photosynthesis. Satellites can detect plant health, or a reaction to photosynthesis, through a Normalized Difference Vegetation Index (NDVI). This can act as a potential proxy for detecting changes in volcanic volatile emissions from space. We tested this method by analyzing 185 Landsat 5 and 8 images of the Tern Lake thermal area (TLTA) in northeast Yellowstone caldera from 1984 to 2022. We compared the NDVI values of the thermal area with those of similar nearby forests that were unaffected by hydrothermal activity to determine how hydrothermal activity impacted the vegetation. From 1984 to 2000, plant health in the TLTA steadily increased relative to the background forests, suggesting that vegetation in the TLTA was fertilized by volcanic CO2 and/or magmatic water. Hydrothermal activity began to stress plants in 2002, and by 2006, large swathes of trees were dying in the hydrothermal area. Throughout most of the 1990s, the least healthy plants were located in the area which became the epicenter of hydrothermal activity in 2000. These findings suggest that plant‐focused measurements are sensitive to minor levels of volcanic unrest which may not be detected by other remote sensing methods, such as infrared temperature measurements. This method could be a safe and effective new tool for detecting changes in volatile emissions in volcanic environments which are dangerous or difficult to access.
... To assess the likelihood of trees having been significantly stressed in the past by volcanic sulfur dioxide (SO 2 ) from the central crater vents, we took two approaches. First, we were guided by in situ measurements taken in the same areas by Jenkins et al. (2012), who assessed the physiological interactions of SO 2 and CO 2 on vegetation on the upper slopes of Turrialba and demonstrated a rapid exponential decay of SO 2 away from the central vent. Second, for long-term exposure we derived the likelihood of exposure per unit area using satellite data sensitive to SO 2 (Fig. 2). ...
... band of a few 100 m around the mostly quietly steaming central vent, which has been thoroughly ecologically evaluated for acid damage (Jenkins et al., 2012). D'Arcy (2018) has assessed this narrow, heavily SO 2 -affected area immediately surrounding the central crater vent of Turrialba, which we avoided, and our sampling sites are mostly within their control zone that is not considered majorly affected by SO 2 but where diffuse CO 2 degassing dominates the excess gas phase (Epiard et al., 2017). ...
... D'Arcy (2018) has assessed this narrow, heavily SO 2 -affected area immediately surrounding the central crater vent of Turrialba, which we avoided, and our sampling sites are mostly within their control zone that is not considered majorly affected by SO 2 but where diffuse CO 2 degassing dominates the excess gas phase (Epiard et al., 2017). Our study area is on the flanks of the volcano, where ASTER-derived SO 2 probability is minimal, and SO 2 influence not detectable on the ground (Jenkins et al., 2012;Campion et al., 2012). Most other volcanoes in Costa Rica emit little to no SO 2 on a decadal timescale, shown by the low or non-existent long-term SO 2 probabilities over the other volcanoes in Costa Rica (white shapes in Fig. 2). ...
We explore the use of active volcanoes to determine the short- and long-term effects of elevated CO2 on tropical trees. Active volcanoes continuously but variably emit CO2 through diffuse emissions on their flanks, exposing the overlying ecosystems to elevated levels of atmospheric CO2. We found tight correlations (r²=0.86 and r²=0.74) between wood stable carbon isotopic composition and co-located volcanogenic CO2 emissions for two of three investigated species (Oreopanax xalapensis and Buddleja nitida), which documents the long-term photosynthetic incorporation of isotopically heavy volcanogenic carbon into wood biomass. Measurements of leaf fluorescence and chlorophyll concentration suggest that volcanic CO2 also has measurable short-term functional impacts on select species of tropical trees. Our findings indicate significant potential for future studies to utilize ecosystems located on active volcanoes as natural experiments to examine the ecological impacts of elevated atmospheric CO2 in the tropics and elsewhere. Results also point the way toward a possible future utilization of ecosystems exposed to volcanically elevated CO2 to detect changes in deep volcanic degassing by using selected species of trees as sensors.
... Delmelle (2003) reported similar problems for coffee plantations situated downwind of Poas Volcano (Costa Rica). Similarly, native vegetation is highly susceptible to SO 2 exposure, as verified along the flanks of Turrialba Volcano (Costa Rica), where a diffuse SO 2 degassing event resulted in an extensive tree-kill zone within the tropical forest (Jenkins et al., 2012). In general, environmental concentrations of SO 2 , the duration of exposure, soil status and plant type and age determine the degree of stress due to SO 2 phytotoxicity (Hell, 2004). ...
Sulfur dioxide (SO2) is a major component of magmatic gas discharges. Once emitted in the atmosphere it can affect the air and land environment at different spatial and temporal scales, with harmful effects on human health and plant communities. We used a dense dataset of continuous SO2 flux and meteorological measurements collected at Vulcano over an 8-year period spanning from May 2008 to February 2016 to model air SO2 concentrations over the island. To this end, we adopted the DISGAS (DISpersion of GAS) numerical code coupled with the Diagnostic Wind Model (DWM). SO2 concentrations in air were determined for three different SO2 emission rates: a reference SO2 flux of ∼18 t/d (the median of more than 800 measurements), an enhanced SO2 flux of 40 t/d (average of all measurements plus 1 σ), and a maximum SO2 flux of 106 t/d (maximum value measured in the investigated period). Maximum SO2 concentrations in air were estimated at the crater, near the high-T fumarole field that is the source of the gas, and ranged from 2000 ppb to ∼24,000 ppb for the reference flux, from 2000 ppb to 51,000 ppb for the enhanced flux and from 5000 ppb to 136,000 ppb for the maximum flux, with peak values in limited areas at the bottom of the crater. These concentrations pose a hazard for people visiting the crater, for sensitive individuals in particular. Based on estimated SO2 concentrations in air, we also consider the phytotoxic effects of SO2 on local vegetation.
Cambridge Core - Plant Sciences - Leaf Optical Properties - by Stéphane Jacquemoud
