Evaluating the Impact of Summer Drought on Vegetation Growth Using Space-Based Solar-Induced Chlorophyll Fluorescence Across Extensive Spatial Measures

Big Data ◽  
2021 ◽  
Author(s):  
Sanjeevi Pandiyan ◽  
Govindjee Govindjee ◽  
S. Meenatchi ◽  
S. Prasanna ◽  
G. Gunasekaran ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Summer Drought ◽  
Vegetation Growth ◽  
Spatial Measures ◽  
The Impact

Heavily data-constrained mechanistic ecohydrological modeling can guide management of pre-Alpine grasslands in the present and future climate

2020 ◽  
Author(s):  
Martina Botter ◽  
Matthias Zeeman ◽  
Paolo Burlando ◽  
Simone Fatichi
Keyword(s):  
Management Strategies ◽  
Climatic Conditions ◽  
Mechanistic Modeling ◽  
System Response ◽  
Summer Drought ◽  
Vegetation Productivity ◽  
Vegetation Growth ◽  
Soil Biogeochemistry ◽  
Alpine Regions ◽  
The Impact

<p><span>The pressure of climate change and increasing food demand on agricultural systems made management strategies crucial for matching the production goals without affecting water quantity and quality. This is, for instance, the case for managed grasslands in the Alpine and pre-alpine regions. This study combines a large suite of observations from the TERENO observatory and ScaleX campaigns with mechanistic modeling, in order to analyze the response of managed grasslands north of the Alps to different climatic conditions and management strategies, aimed at evaluating changes in the ecohydrological response, as well as carbon, water and nutrient fluxes.  </span></p><p><span>First, we used the data to evaluate the performance of the mechanistic Tethys-Chloris (T&C) model, which fully integrates the solution of surface energy balance and hydrological budget with vegetation dynamics and soil biogeochemistry, for the period 2012-2016. This is characterized by significant climatic inter-annual variability and including </span><span>the extraordinarily warm year 2015. The observations cover three different grassland sites composed by flux towers, soil moisture and temperature probes, lysimeters, nutrient leaching and dedicated vegetation sampling campaigns, allowing an unprecedented validation opportunity of model skills for multiple variable and temporal scales. The observed system response, in terms of water, energy and nutrients dynamics, are successfully reproduced, which increases confidence on the model capability to reproduce the feedbacks among hydrology, vegetation growth and soil biogeochemistry. The results highlight the impact of an early begin of the growing season on the vegetation productivity and nutrients leaching in years with reduced snow cover,  as well as the effects of summer drought on vegetation productivity. </span></p><p><span>Second, numerical experiments are used to test the response of this ecosystem to different grassland fertilization and cutting scenarios in the present climate and in warmer and CO<sub>2</sub> enriched conditions. Of particular interest are the number and timing of grass cuts and fertilizer applications that could optimize grassland productivity without compromising water quality in a warmer climate. </span></p>

Climate-forced changes of bio-productivity of Belorussian terrestrial ecosystems

2019 ◽  
pp. 77-88
Author(s):  
S. A. Lysenko
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Vegetation Index ◽  
Precipitation Amount ◽  
Terrestrial Ecosystems ◽  
Vegetation Period ◽  
Climatic Trend ◽  
Vegetation Growth ◽  
Current Century ◽  
The Impact

The spatial and temporal particularities of Normalized Differential Vegetation Index (NDVI) changes over territory of Belarus in the current century and their relationship with climate change were investigated. The rise of NDVI is observed at approximately 84% of the Belarus area. The statistically significant growth of NDVI has exhibited at nearly 35% of the studied area (t-test at 95% confidence interval), which are mainly forests and undeveloped areas. Croplands vegetation index is largely descending. The main factor of croplands bio-productivity interannual variability is precipitation amount in vegetation period. This factor determines more than 60% of the croplands NDVI dispersion. The long-term changes of NDVI could be explained by combination of two factors: photosynthesis intensifying action of carbon dioxide and vegetation growth suppressing action of air warming with almost unchanged precipitation amount. If the observed climatic trend continues the croplands bio-productivity in many Belarus regions could be decreased at more than 20% in comparison with 2000 year. The impact of climate change on the bio-productivity of undeveloped lands is only slightly noticed on the background of its growth in conditions of rising level of carbon dioxide in the atmosphere.

scholarly journals Coastal Mangrove Response to Marine Erosion: Evaluating the Impacts of Spatial Distribution and Vegetation Growth in Bangkok Bay from 1987 to 2017

2020 ◽  
Vol 12 (2) ◽  
pp. 220 ◽  
Author(s):  
Han Xiao ◽  
Fenzhen Su ◽  
Dongjie Fu ◽  
Qi Wang ◽  
Chong Huang
Keyword(s):  
Spatial Distribution ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Mangrove Ecosystem ◽  
Early Growth ◽  
Growth Stages ◽  
Human Disturbances ◽  
Vegetation Growth ◽  
Two Parameters ◽  
The Impact

Long time-series monitoring of mangroves to marine erosion in the Bay of Bangkok, using Landsat data from 1987 to 2017, shows responses including landward retreat and seaward extension. Quantitative assessment of these responses with respect to spatial distribution and vegetation growth shows differing relationships depending on mangrove growth stage. Using transects perpendicular to the shoreline, we calculated the cross-shore mangrove extent (width) to represent spatial distribution, and the normalized difference vegetation index (NDVI) was used to represent vegetation growth. Correlations were then compared between mangrove seaside changes and the two parameters—mangrove width and NDVI—at yearly and 10-year scales. Both spatial distribution and vegetation growth display positive impacts on mangrove ecosystem stability: At early growth stages, mangrove stability is positively related to spatial distribution, whereas at mature growth the impact of vegetation growth is greater. Thus, we conclude that at early growth stages, planting width and area are more critical for stability, whereas for mature mangroves, management activities should focus on sustaining vegetation health and density. This study provides new rapid insights into monitoring and managing mangroves, based on analyses of parameters from historical satellite-derived information, which succinctly capture the net effect of complex environmental and human disturbances.

Assessing the impact of seasonal precipitation and temperature on vegetation in a grass-dominated rangeland

2014 ◽  
Vol 36 (2) ◽  
pp. 185 ◽  
Author(s):  
Fang Chen ◽  
Keith T. Weber
Keyword(s):  
Vegetation Index ◽  
Climatic Factors ◽  
Growing Season ◽  
Vegetation Growth ◽  
Factors Affecting ◽  
Growing Seasons ◽  
Normalised Difference Vegetation Index ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
The Impact ◽  
Precipitation And Temperature

Changes in vegetation are affected by many climatic factors and have been successfully monitored through satellite remote sensing over the past 20 years. In this study, the Normalised Difference Vegetation Index (NDVI), derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Terra satellite, was selected as an indicator of change in vegetation. Monthly MODIS composite NDVI at a 1-km resolution was acquired throughout the 2004–09 growing seasons (i.e. April–September). Data describing daily precipitation and temperature, primary factors affecting vegetation growth in the semiarid rangelands of Idaho, were derived from the Surface Observation Gridding System and local weather station datasets. Inter-annual and seasonal fluctuations of precipitation and temperature were analysed and temporal relationships between monthly NDVI, precipitation and temperature were examined. Results indicated NDVI values observed in June and July were strongly correlated with accumulated precipitation (R2 >0.75), while NDVI values observed early in the growing season (May) as well as late in the growing season (August and September) were only moderately related with accumulated precipitation (R2 ≥0.45). The role of ambient temperature was also apparent, especially early in the growing season. Specifically, early growing-season temperatures appeared to significantly affect plant phenology and, consequently, correlations between NDVI and accumulated precipitation. It is concluded that precipitation during the growing season is a better predictor of NDVI than temperature but is interrelated with influences of temperature in parts of the growing season.

scholarly journals Determination of the influence of herbicides on dicotyledons plant transpiration using the sap flow method

2014 ◽  
Vol 60 (No. 12) ◽  
pp. 562-568 ◽  
Author(s):  
V. Brant ◽  
J. Pivec ◽  
K. Hamouzová ◽  
P. Zábranský ◽  
J. Satrapová ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Transpiration Rate ◽  
Sap Flow ◽  
Herbicide Application ◽  
Plant Transpiration ◽  
Flow Method ◽  
Infrared Gas Analyser ◽  
The Impact ◽  
Q Values

Physiological parameters are sensitive and provide information on the toxicity of herbicides in plants. The impact of herbicide application on plant transpiration was evaluated by the sap flow method during 2009&ndash;2011. The aim of this work was to verify the sap flow method for determining the effect of herbicides on the basis of continuous measurements of the transpiration flow. Helianthus annuus was used as a model plant species. The two different herbicides tested in this study differed by the effect of active ingredients bromoxynil and clopyralid. The water flow was measured using sap flow meter T4.2. The impact of herbicides was assessed by comparing measured transpiration rate (Q) after herbicide application with an extrapolation of transpiration rate of plants before herbicide treatment (Q<sub>calc</sub>). After treatment with bromoxynil the Q values decreased significantly compared to Q<sub>calc</sub>. For plants treated by clopyralid, the decline of actual transpiration (Q) compared with the modelled one (Q<sub>calc</sub>) was less substantial and the plants continued to transpire after the treatment. The effect of herbicides was also verified using infrared gas analyser and chlorophyll fluorescence meter.

scholarly journals Growth control of herbaceous ground cover and egg quality from an integrated poultry-hazelnut orchard system

2020 ◽  
Author(s):  
Carlo Cosentino ◽  
Pierangelo Freschi ◽  
Simonetta Fascetti ◽  
Rosanna Paolino ◽  
Mauro Musto
Keyword(s):  
Egg Quality ◽  
Cynodon Dactylon ◽  
Growth Control ◽  
Alpha Diversity ◽  
Ground Cover ◽  
Control Group ◽  
Diversity Analysis ◽  
Positive Role ◽  
Vegetation Growth ◽  
The Impact

The present study was designed to assess the impact of hen grazing on plant biodiversity in the ground cover of hazelnut orchards, as well as the quality of eggs from hens grazing in the orchards. Two different sites of hazelnut orchards located in Basilicata region were selected to conduct this study. The results showed that hen grazing affected the composition of herbaceous stratum of the orchards. By using the quadrat method, a total of 99 (46 in site A and 53 in site B) plant species were identified at the beginning of the trial. After hen grazing, the number of identified plants dropped to 72 (30 in site A and 42 in site B). Amongst the most consumed species we found Lolium sp., Trifolium sp., Polygonum sp., Cichorium intybus, Cynodon dactylon. Alpha diversity analysis (species richness, diversity and evenness) as well as beta diversity analysis (Morisita-Horn and Sørensen indices) confirmed that hen grazing played a role in controlling vegetation growth. Concerning egg quality, most of the chemical parameters differed significantly when comparing the eggs from the sites with those from the control group, indicating that egg quality was influenced by the food resources available in each site. Overall, our results confirm that poultry may play a positive role in an orchard system.

scholarly journals The Impacts of Growth and Environmental Parameters on Solar-Induced Chlorophyll Fluorescence at Seasonal and Diurnal Scales

2019 ◽  
Vol 11 (17) ◽  
pp. 2002
Author(s):  
Leizhen Liu ◽  
Wenhui Zhao ◽  
Jianjun Wu ◽  
Shasha Liu ◽  
Yanguo Teng ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Water Stress ◽  
Growth Parameters ◽  
Pearson Correlation ◽  
Canopy Structure ◽  
Principal Component ◽  
Environmental Parameters ◽  
Area Index ◽  
Relationship Of ◽  
The Impact

Solar-induced chlorophyll fluorescence (SIF) is considered to be a potential indicator of photosynthesis. However, the impact of growth and environmental parameters on SIF at different time-scales remains unclear, which has greatly restricted the application of SIF in detecting photosynthesis variations. Thus, in this study, the impact of growth and environmental parameters on SIF was thoroughly clarified. Here, continuous time series of canopy SIF (760 nm, F760) over wheat and maize was measured based on an automated spectroscopy system. Meanwhile, field measurements of growth and environmental parameters were also collected using commercial-grade devices. Relationships of these parameters with F760, apparent SIF (F760/solar radiance, AF760), and SIF yield (F760/canopy radiance of 685 nm, Fy760) were analyzed using principal component analysis (PCA) and Pearson correlation to reveal their impacts on SIF. Results showed that F760 at seasonal and diurnal scales were mainly driven by solar radiation (SWR), leaf area index (LAI), chlorophyll content (Chl), mean leaf inclination angle (MTA), and relative water content (RWC). Other environmental parameters, including air temperature (Ta), relative humidity (Rh), vapor pressure deficit (VPD), and soil moisture (SM), contribute less to the variation of seasonal or diurnal F760. AF760 and Fy760 are likely to be less dependent on Ta, Rh, and VPD due to the removal of the impact from SWR, but an enhanced relationship of AF760 (and Fy760) with SM was observed, particularly under water stress. Compared with F760, wheat AF760 was better correlated to LAI and RWC as expected, while maize AF760 did not show an enhanced relationship with all growth parameters, probably due to its complicated canopy structure. The relationship of wheat Fy760 with canopy structure parameters was further reduced, except for maize measurements. Furthermore, SM-induced water stress and phenological stages should be taken into consideration when we interpret the seasonal and diurnal patterns of SIF since they were closely related to photosynthesis and plant growth (e.g., LAI in our study). To our knowledge, this is the first exploration of the impacts of growth and environmental parameters on SIF based on continuous ground measurements, not only at a seasonal scale but also at a diurnal scale. Our results could provide deep insight into the variation of SIF signals and also promote the further application of SIF in the health assessments of terrestrial ecosystems.

scholarly journals The impact of drought on total ozone flux in a mountain Norway spruce forest

2020 ◽  
Vol 66 (No. 7) ◽  
pp. 280-278 ◽  
Author(s):  
Thomas Agyei ◽  
Stanislav Juráň ◽  
Kojo Kwakye Ofori-Amanfo ◽  
Ladislav Šigut ◽  
Otmar Urban ◽  
...  
Keyword(s):  
Norway Spruce ◽  
Stomatal Closure ◽  
Severe Drought ◽  
Summer Drought ◽  
Spruce Forest ◽  
Soil Humidity ◽  
Drought Period ◽  
The Impact ◽  
Mild Drought ◽  
Norway Spruce Forest

In order to understand the impact of summer drought on dry deposition of tropospheric ozone (O<sub>3</sub>), we compared severe and mild drought periods of summer 2018 in a mountain Norway spruce forest at Bílý Kříž, Beskydy Mts. An eddy covariance technique was applied to measure diurnal courses of the ecosystem O<sub>3</sub> and CO<sub>2</sub> fluxes. Low O<sub>3</sub> deposition was recorded in the morning and evening, while the highest CO<sub>2</sub> and O<sub><sup>3</sup></sub> fluxes were recorded during the central hours of the day. Total O<sub>3</sub> deposition during severe drought (soil humidity 13%) was significantly higher than the deposition during the mild drought period (soil humidity 19%). Our data indicate that high vapour pressure deficit and low soil humidity during severe drought led to the stomatal closure, while non-stomatal O<sub>3</sub> deposition, associated with chemical reactions of O<sub>3</sub> with NO and volatile organic compounds, are responsible for higher total O<sub>3</sub> deposition during the severe drought period. Therefore, we assume that under severe drought stomatal O<sub>3</sub> uptake decreases but non-stomatal depositions to forest ecosystems substantially increase.

The impact of the 2009/2010 drought on vegetation growth and terrestrial carbon balance in Southwest China

2019 ◽  
Vol 269-270 ◽  
pp. 239-248 ◽  
Author(s):  
Xiangyi Li ◽  
Yue Li ◽  
Anping Chen ◽  
Mengdi Gao ◽  
Ingrid J. Slette ◽  
...  
Keyword(s):  
Carbon Balance ◽  
Southwest China ◽  
Terrestrial Carbon ◽  
Vegetation Growth ◽  
The Impact

Assessing and monitoring the vulnerability to drought and climate anomalies of Mediterranenan oak forests by using NDVI

2020 ◽  
Author(s):  
Maria Castellaneta ◽  
Angelo Rita ◽  
J. Julio Camarero ◽  
Michele Colangelo ◽  
Angelo Nolè ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Time Series ◽  
Tree Mortality ◽  
Vegetation Index ◽  
Google Earth ◽  
Oak Forests ◽  
Summer Drought ◽  
Area Index ◽  
Ndvi Time Series ◽  
The Impact

&lt;p&gt;Several die-off episodes related to heat weaves and drought spells have evidenced the high vulnerability of Mediterranean oak forests. These events consisted in the loss in tree vitality and manifested as growths decline, elevated crown transparency (defoliation) and rising tree mortality rate. In this context, the changes in vegetation productivity and canopy greenness may represent valuable proxies to analyze how extreme climatic events trigger forest die-off. Such changes in vegetation status may be analyzed using remote-sensing data, specifically multi-temporal spectral information. For instance, the Normalized Difference Vegetation Index (NDVI) measures changes in vegetation greenness and is a proxy of changes in leaf area index (LAI), forest aboveground biomass and productivity. In this study, we analyzed the temporal patterns of vegetation in three Mediterranean oak forests showing recent die-off in response to the 2017 severe summer drought. For this purpose, we used an open-source platform (Google Earth Engine) to extract collections of MODIS NDVI time-series from 2000 to 2019. The analysis of both NDVI trends and anomalies were used to infer differential patterns of vegetation phenology among sites comparing plots where most trees were declining and showed high defoliation (test) versus plots were most trees were considered healthy (ctrl) and showed low or no defoliation. Here we discuss: i) the likely offset in NDVI time-series between test- versus ctrl- sites; and ii) the impact of summer droughts &amp;#160;on NDVI.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Keywords&lt;/strong&gt;: climate change, forest vulnerability, time series, remote sensing.&lt;/p&gt;

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