scholarly journals Ecohydrological Optimality in Northeast China Transect

2016 ◽  
Author(s):  
Qinshu Li ◽  
Zhentao Cong ◽  
Kangle Mo ◽  
Lexin Zhang
Keyword(s):  
Optimality Theory ◽  
Vegetation Cover ◽  
Northeast China ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Precipitation Amount ◽  
Canopy Cover ◽  
Leaf Angle ◽  
Vegetation Transition ◽  
Impacts Of Climate Change

Abstract. Northeast China Transect (NECT) is one of International Geosphere-Biosphere Program (IGBP) terrestrial transects. In this transect area, there is a significant precipitation gradient from east to west, as well as a vegetation transition of forest-grasslands-dessert. In this paper, we use vegetation cover as an index to describe the properties of vegetation distribution and dynamics in NECT. Normalized Difference Vegetation Index (NDVI) is used to derive the actual vegetation cover M, while Eagleson's ecohydrological optimality theory is applied to calculate the optimal canopy cover M* along NECT. The result indicates that the theoretical M* fits the actual M well (for forest, M* = 0.822 while M = 0.826; for grassland, M* = 0.353 while M = 0.352; the correlation coefficient between M and M* is 0.81). Water balance are also calculated using Eagleson's theory. The result is compared to the field measured data and shows a relative good match, which further demonstrates the reliability of the ecohydrological optimality theory in this area. M* increases with the decrease of LAI, stem fraction, temperature, and the increase of leaf angle and precipitation amount. The ecohydrological optimality method offers a quantitative way to analyse the impacts of climate change to canopy cover quantitatively, thus providing advices for eco-restoration projects.

scholarly journals Ecohydrological Optimality in Northeast China Transect

2017 ◽  
Author(s):  
Zhentao Cong ◽  
Qinshu Li ◽  
Kangle Mo ◽  
Lexin Zhang
Keyword(s):  
Water Balance ◽  
Optimality Theory ◽  
Northeast China ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Precipitation Amount ◽  
Canopy Cover ◽  
Sensitivity Analyses ◽  
Leaf Angle ◽  
Vegetation Distribution

Abstract. Northeast China Transect (NECT) is one of International Geosphere-Biosphere Program (IGBP) terrestrial transects., where there is a significant precipitation gradient from east to west, as well as a vegetation transition of forest-grasslands-dessert. It is interesting to understand vegetation distribution and dynamics under water limitation in this transect. We take canopy cover (M), derived from Normalized Difference Vegetation Index (NDVI), as an index to describe the properties of vegetation distribution and dynamics in NECT. In Eagleson's ecohydrological optimality theory, the optimal canopy cover (M*) is determined by the trade-off of water supply depending on water balance and water demand depending on canopy transpiration. We apply Eagleson’s ecohydrological optimality method in NECT based on data from 2000 to 2013 to get M*, then compare with M from NDVI, furthermore to discuss the sensitivity of M* to vegetation properties and climate factors. The result indicates that the average M* fits the actual M well (for forest, M* = 0.822 while M = 0.826 for grassland, M* = 0.353 while M = 0.352; the correlation coefficient between M and M* is 0.81). The result of water balance also matches the field-measured data in references. The sensitivity analyses show that M* decreases with the increase of LAI, stem fraction, temperature, while increases with the increase of leaf angle and precipitation amount. The Eagleson's ecohydrological optimality method offers a quantitative way to understand the impacts of climate change to canopy cover quantitatively, and provides guidelines for eco-restoration projects.

scholarly journals Ecohydrological optimality in the Northeast China Transect

2017 ◽  
Vol 21 (5) ◽  
pp. 2449-2462 ◽  
Author(s):  
Zhentao Cong ◽  
Qinshu Li ◽  
Kangle Mo ◽  
Lexin Zhang ◽  
Hong Shen
Keyword(s):  
Climate Change ◽  
Water Balance ◽  
Optimality Theory ◽  
Northeast China ◽  
Precipitation Amount ◽  
Canopy Cover ◽  
Sensitivity Analyses ◽  
Leaf Angle ◽  
Vegetation Distribution ◽  
Area Index

Abstract. The Northeast China Transect (NECT) is one of the International Geosphere-Biosphere Program (IGBP) terrestrial transects, where there is a significant precipitation gradient from east to west, as well as a vegetation transition of forest–grassland–desert. It is remarkable to understand vegetation distribution and dynamics under climate change in this transect. We take canopy cover (M), derived from Normalized Difference Vegetation Index (NDVI), as an index to describe the properties of vegetation distribution and dynamics in the NECT. In Eagleson's ecohydrological optimality theory, the optimal canopy cover (M*) is determined by the trade-off between water supply depending on water balance and water demand depending on canopy transpiration. We apply Eagleson's ecohydrological optimality method in the NECT based on data from 2000 to 2013 to get M*, which is compared with M from NDVI to further discuss the sensitivity of M* to vegetation properties and climate factors. The result indicates that the average M* fits the actual M well (for forest, M*  =  0.822 while M  =  0.826; for grassland, M*  =  0.353 while M  =  0.352; the correlation coefficient between M and M* is 0.81). Results of water balance also match the field-measured data in the references. The sensitivity analyses show that M* decreases with the increase of leaf area index (LAI), stem fraction and temperature, while it increases with the increase of leaf angle and precipitation amount. Eagleson's ecohydrological optimality method offers a quantitative way to understand the impacts of climate change on canopy cover and provides guidelines for ecorestoration projects.

scholarly journals Does Anthropogenic Land Use Change Play a Role in Changes of Precipitation Frequency and Intensity over the Loess Plateau of China?

2018 ◽  
Vol 10 (11) ◽  
pp. 1818 ◽  
Author(s):  
Zhengjia Liu ◽  
Yansui Liu
Keyword(s):  
Loess Plateau ◽  
Vegetation Cover ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Regional Scale ◽  
Precipitation Amount ◽  
The Loess Plateau ◽  
Precipitation Frequency ◽  
Intensity Changes ◽  
Vegetation Cover Change

Human transformation of landscapes is pervasive and accelerating across the Earth. However, existing studies have not provided a comprehensive picture of how precipitation frequency and intensity respond to vegetation cover change. Therefore, this study took the Loess Plateau as a typical example, and used satellite-based Normalized Difference Vegetation Index (NDVI) data and daily gridded climatic variables to assess the responses of precipitation dynamics to human-induced vegetation cover change. Results showed that the total precipitation amount exhibited little change at the regional scale, showing an upward but statistically insignificant (p > 0.05) trend of 7.6 mm/decade in the period 1982–2015. However, the frequency of precipitation with different intensities showed large variations over most of the Loess Plateau. The number of rainy days (light, moderate, heavy, very heavy and severe precipitation) increased in response to increased vegetation cover, especially in the central-eastern Loess Plateau. Anthropogenic land cover change is largely responsible for precipitation intensity changes. Additionally, this study also observed high spatially explicit heterogeneity in different precipitation intensities in response to vegetation cover change across the Loess Plateau. These findings provide some reference information for our understanding of precipitation frequency and intensity changes in response to regional vegetation cover change in the Loess Plateau.

scholarly journals Applying High-Resolution Visible-Channel Aerial Scan of Crop Canopy to Precision Irrigation Management

Proceedings ◽  
2018 ◽  
Vol 2 (7) ◽  
pp. 335 ◽  
Author(s):  
Assaf Chen ◽  
Valerie Orlov-Levin ◽  
Moshe Meron
Keyword(s):  
Vegetation Cover ◽  
Vegetation Index ◽  
Near Infrared ◽  
Normalized Difference Vegetation Index ◽  
Low Cost ◽  
Irrigation Management ◽  
Digital Camera ◽  
Canopy Cover ◽  
Crop Canopy ◽  
Irrigation Uniformity

Canopy cover (or vegetation cover) maps serve in irrigation management mainly to determine the primary evapotranspiration (ET) coefficient, as radiation interception and evaporative surface area are directly related to canopy cover. Crop size and development with time depends on water supply; therefore, crop canopy maps are tools for the detection of the spatial uniformity of irrigation systems. Several aerial scan campaigns were deployed in the Upper Galilee of Israel in the 2017 growing season to follow up and evaluate the irrigation uniformity and crop coefficients of peanuts and cotton by RGB scans of a Phantom 4 multirotor unmanned aerial vehicle (UAV). Foliage intensity and coverage were enhanced by a green-red vegetation index (GRVI), which is a normalized difference vegetation index (NDVI)-like process where the green channel replaced the near-infrared (NIR). The results demonstrated that the GRVI is suitable for the purpose of determining the vegetation cover. Furthermore, the GRVI yielded better results than the NDVI in recognizing phenological crop changes (especially senescence). Therefore, this research proves the applicability of a low-cost digital camera mounted on an easily accessible UAV for crop cover and actual, in-field, ET coefficients determination and irrigation uniformity evaluation.

scholarly journals Urban Fire Severity and Vegetation Dynamics in Southern California

2020 ◽  
Vol 13 (1) ◽  
pp. 19
Author(s):  
Lauren E. H. Mathews ◽  
Alicia M. Kinoshita
Keyword(s):  
Vegetation Cover ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Current Knowledge ◽  
Fire Severity ◽  
Satellite Image ◽  
Burn Severity ◽  
Native Vegetation ◽  
Riparian Areas ◽  
The Impact

A combination of satellite image indices and in-field observations was used to investigate the impact of fuel conditions, fire behavior, and vegetation regrowth patterns, altered by invasive riparian vegetation. Satellite image metrics, differenced normalized burn severity (dNBR) and differenced normalized difference vegetation index (dNDVI), were approximated for non-native, riparian, or upland vegetation for traditional timeframes (0-, 1-, and 3-years) after eleven urban fires across a spectrum of invasive vegetation cover. Larger burn severity and loss of green canopy (NDVI) was detected for riparian areas compared to the uplands. The presence of invasive vegetation affected the distribution of burn severity and canopy loss detected within each fire. Fires with native vegetation cover had a higher severity and resulted in larger immediate loss of canopy than fires with substantial amounts of non-native vegetation. The lower burn severity observed 1–3 years after the fires with non-native vegetation suggests a rapid regrowth of non-native grasses, resulting in a smaller measured canopy loss relative to native vegetation immediately after fire. This observed fire pattern favors the life cycle and perpetuation of many opportunistic grasses within urban riparian areas. This research builds upon our current knowledge of wildfire recovery processes and highlights the unique challenges of remotely assessing vegetation biophysical status within urban Mediterranean riverine systems.

Change on detection of vegetation cover and soil salinity using GIS technique in Diyala Governorate, Iraq

2021 ◽  
Vol 30 (1) ◽  
pp. 148-158
Author(s):  
Haneen Adeeb ◽  
Yaseen Al-Timimi
Keyword(s):  
Soil Salinity ◽  
Vegetation Cover ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Inverse Correlation ◽  
Salinity Changes ◽  
Gis Technique ◽  
Salinity Index ◽  
Remote Sensing Techniques ◽  
Strong Inverse Correlation

Soil salinity is one of the most important problems of land degradation, that threatening the environmental, economic and social system. The aim of this study to detect the changes in soil salinity and vegetation cover for Diyala Governorate over the period from 2005 to 2020, through the use of remote sensing techniques and geographic information system. The normalized difference vegetation index (NDVI) and salinity index (SI) were used, which were applied to four of the Landsat ETM+ and Landsat OLI satellite imagery. The results showed an increase in soil salinity from 7.27% in the period 2005–2010 to 27.03% in 2015–2020, as well as an increase in vegetation from 10% to 24% in the same period. Also the strong inverse correlation between the NDVI and the SI showed that vegetation is significantly affected and directly influenced by soil salinity changes

scholarly journals Consideration of NDVI thematic changes in density analysis and floristic composition of Wadi Yalamlam, Saudi Arabia

2018 ◽  
Vol 7 (4) ◽  
pp. 297-306 ◽  
Author(s):  
Amal Y. Aldhebiani ◽  
Mohamed Elhag ◽  
Ahmad K. Hegazy ◽  
Hanaa K. Galal ◽  
Norah S. Mufareh
Keyword(s):  
Saudi Arabia ◽  
Vegetation Cover ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Remote Sensing Data ◽  
Floristic Composition ◽  
Water Source ◽  
Shannon Index ◽  
Landsat 8 ◽  
Main Stream

Abstract. Wadi Yalamlam is known as one of the significant wadis in the west of Saudi Arabia. It is a very important water source for the western region of the country. Thus, it supplies the holy places in Mecca and the surrounding areas with drinking water. The floristic composition of Wadi Yalamlam has not been comprehensively studied. For that reason, this work aimed to assess the wadi vegetation cover, life-form presence, chorotype, diversity, and community structure using temporal remote sensing data. Temporal datasets spanning 4 years were acquired from the Landsat 8 sensor in 2013 as an early acquisition and in 2017 as a late acquisition to estimate normalized difference vegetation index (NDVI) changes. The wadi was divided into seven stands. Stands 7, 1, and 3 were the richest with the highest Shannon index values of 2.98, 2.69, and 2.64, respectively. On the other hand, stand 6 has the least plant biodiversity with a Shannon index of 1.8. The study also revealed the presence of 48 different plant species belonging to 24 families. Fabaceae (17 %) and Poaceae (13 %) were the main families that form most of the vegetation in the study area, while many families were represented by only 2 % of the vegetation of the wadi. NDVI analysis showed that the wadi suffers from various types of degradation of the vegetation cover along with the wadi main stream.

scholarly journals Assessing Snow Phenology and Its Environmental Driving Factors in Northeast China

2022 ◽  
Vol 14 (2) ◽  
pp. 262
Author(s):  
Hui Guo ◽  
Xiaoyan Wang ◽  
Zecheng Guo ◽  
Siyong Chen
Keyword(s):  
Snow Cover ◽  
Northeast China ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Water Cycle ◽  
Water Source ◽  
Driving Factors ◽  
Change Rate ◽  
Mean Temperature ◽  
Forested Areas

Snow cover is an important water source and even an Essential Climate Variable (ECV) as defined by the World Meteorological Organization (WMO). Assessing snow phenology and its driving factors in Northeast China will help with comprehensively understanding the role of snow cover in regional water cycle and climate change. This study presents spatiotemporal variations in snow phenology and the relative importance of potential drivers, including climate, geography, and the normalized difference vegetation index (NDVI), based on the MODIS snow products across Northeast China from 2001 to 2018. The results indicated that the snow cover days (SCD), snow cover onset dates (SCOD) and snow cover end dates (SCED) all showed obvious latitudinal distribution characteristics. As the latitude gradually increases, SCD becomes longer, SCOD advances and SCED delays. Overall, there is a growing tendency in SCD and a delayed trend in SCED across time. The variations in snow phenology were driven by mean temperature, followed by latitude, while precipitation, aspect and slope all had little effect on the SCD, SCOD and SCED. With decreasing temperature, the SCD and SCED showed upward trends. The mean temperature has negatively correlation with SCD and SCED and positively correlation with SCOD. With increasing latitude, the change rate of the SCD, SCOD and SCED in the whole Northeast China were 10.20 d/degree, −3.82 d/degree and 5.41 d/degree, respectively, and the change rate of snow phenology in forested areas was lower than that in nonforested areas. At the same latitude, the snow phenology for different underlying surfaces varied greatly. The correlations between the snow phenology and NDVI were mainly positive, but weak correlations accounted for a large proportion.

scholarly journals Heat Islands in the city of San Francisco de Campeche: Detection and solution

2020 ◽  
pp. 16-20
Author(s):  
Román Alejandro Canul-Turriza ◽  
Francisco Javier Barrera-Lao ◽  
Gabriela Patricia Aldana Narváez
Keyword(s):  
Soil Temperature ◽  
San Francisco ◽  
Vegetation Cover ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Heat Islands ◽  
Mathematical Algorithm ◽  
Green Areas ◽  
Landsat 5 Tm ◽  
The City

This paper presents the identification of heat islands in the city of San Francisco de Campeche, period 1990 - 2020 and their relationship with changes in the vegetation cover areas. To identify the heat islands in the city, 6 Landsat 5 (TM), 7 (TM) and 8 (OIL) images were obtained from the USGS database (http://earthexplorer.usgs.gov/). In geographic information software, soil temperature was calculated from a mathematical algorithm applied to thermal infrared bands 6 and 10, in addition, the Normalized Difference Vegetation Index (NDVI) was calculated, in order to find a relationship between changes in temperature and vegetation cover. It was found that the green areas have reduced their surface by more than 50% and the soil temperature has increased up to 7 ° C

scholarly journals Impact of resettlement scheme on vegetation cover and its implications on conservation in Chewaka district of Ethiopia

2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Alemayehu Abera ◽  
Teshome Yirgu ◽  
Abera Uncha
Keyword(s):  
Rural Communities ◽  
Vegetation Cover ◽  
Vegetation Index ◽  
Management Practices ◽  
Normalized Difference Vegetation Index ◽  
Average Rate ◽  
Sampling Procedure ◽  
Rapid Reduction ◽  
Sparse Vegetation ◽  
Major Factors

Abstract Background Resettlement has been conceived as a viable solution to the continual impoverishment and destitution of Ethiopian rural communities. However, it has considerable impacts on natural resources of the environment at destination areas. This study was carried out to evaluate impact of resettlement scheme on vegetation cover and its implications on conservation in Chewaka district of Ethiopia. Methods The study utilized ArcGIS10.3, ERDAS Imagine 9.1, Landsat imageries of 2000, 2009, 2018 and socio-economic data to analyze the LULC of the district. Normalized Difference Vegetation Index was employed to detect vegetation cover changes of the area. The study was conducted on the seven kebeles of Chewaka district and the total households of the sample kebeles are 3340. Through multistage sampling procedure a total of 384 households were selected from sample kebeles. Data were collected using questionnaires, GPS, interviews, focus group discussions and field observations. The collected data were analyzed both quantitatively and qualitatively. Results The results showed that Chewaka district has undergone substantial LULC change since population resettlement in the area. A rapid reduction of woodland (34.6%), forest (59.9%), grassland (50.5%) and bareland (46.8%) took place between 2000 and 2018, while built-up areas and cultivated lands have expanded at an average rate of 90.7 and 1515.7 ha/year respectively. The results of NDVI revealed that the extent of dense and sparse vegetation cover have decreased by 26.1% and 20.6% respectively, whereas non-vegetation cover has increased by 14,340.2 ha during the study period. It was found that rapid population growth following resettlement program, farmland and settlement expansion, deforestation, human-induced forest fire, lack of land use plan, unwise utilization and low management practices were the major factors that underpin the observed changes in the area. Conclusions Resettlement scheme has resulted in the depletion and dynamics of vegetation cover in Chewaka district. Therefore, the study suggests urgent attention on conservation of the remaining vegetation resources for sustainable utilization.

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