scholarly journals Rainfall Trend and Its Relationship with Normalized Difference Vegetation Index in a Restored Semi-Arid Wetland of South Africa

2020 ◽  
Vol 12 (21) ◽  
pp. 8919
Author(s):  
Florence M. Murungweni ◽  
Onisimo Mutanga ◽  
John O. Odiyo
Keyword(s):  
South Africa ◽  
Quantile Regression ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Rainfall Data ◽  
Ecosystem Change ◽  
Annual Rainfall ◽  
Rainfall Trend ◽  
Vegetation Productivity ◽  
Rainfall Trends

Clearance of terrestrial wetland vegetation and rainfall variations affect biodiversity. The rainfall trend–NDVI (Normalized Difference Vegetation Index) relationship was examined to assess the extent to which rainfall affects vegetation productivity within Nylsvley, Ramsar site in Limpopo Province, South Africa. Daily rainfall data measured from eight rainfall stations between 1950 and 2016 were used to generate seasonal and annual rainfall data. Mann-Kendall and quantile regression were applied to assess trends in rainfall data. NDVI was derived from satellite images from between 1984 and 2003 using Zonal statistics and correlated with rainfall of the same period to assess vegetation dynamics. Mann-Kendall and Sen’s slope estimator showed only one station had a significant increasing rainfall trend annually and seasonally at p < 0.05, whereas all the other stations showed insignificant trends in both rainfall seasons. Quantile regression showed 50% and 62.5% of the stations had increasing annual and seasonal rainfall, respectively. Of the stations, 37.5% were statistically significant at p < 0.05, indicating increasing and decreasing rainfall trends. These rainfall trends show that the rainfall of Nylsvley decreased between 1995 and 2003. The R2 between rainfall and NDVI of Nylsvley is 55% indicating the influence of rainfall variability on vegetation productivity. The results underscore the impact of decadal rainfall patterns on wetland ecosystem change.

scholarly journals A new global dataset of phase synchronization of temperature and precipitation: its climatology and contribution to global vegetation productivity

2018 ◽  
Author(s):  
Zhigang Sun ◽  
Zhu Ouyang ◽  
Xubo Zhang ◽  
Wei Ren
Keyword(s):  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Phase Synchronization ◽  
Temporal Variations ◽  
Coefficient Of Determination ◽  
Terrestrial Vegetation ◽  
Maximum Increase ◽  
Vegetation Productivity ◽  
Temperature And Precipitation ◽  
Maximum Value

Abstract. Besides cumulative temperature and precipitation, the phase synchronization of temperature and precipitation also helps to regulate vegetation distribution and productivity across global lands. However, the phase synchronization has been rarely considered in previous studies related to climate and biogeography due to a lack of a robust and quantitative approach. In this study, we proposed a synchronization index of temperature and precipitation (SI-TaP) and then investigated its global spatial distribution, interannual fluctuation, and long-term trend derived from a global 60-year dataset of meteorological forcings. Further investigation was conducted to understand the relationship between SI-TaP and the annually summed Normalized Difference Vegetation Index (NDVI), which could be a proxy of terrestrial vegetation productivity. Results show differences in both spatial patterns and temporal variations between SI-TaP and air temperature and precipitation, but SI-TaP may help to explain the distribution and productivity of terrestrial vegetation. About 60 % of regions where annually summed NDVI is greater than half of its maximum value overlap regions where SI-TaP is greater than half of its maximum value. By using SI-TaP to explain vegetation productivity along with temperature and precipitation, the maximum increase in the coefficient of determination is 0.66 across global lands. Results from this study suggest that the proposed SI-TaP index is helpful to better understand climate change and its relation to the biota. Dataset available at http://www.dx.doi.org/10.11922/sciencedb.642 or http://www.sciencedb.cn/dataSet/handle/642.

scholarly journals Uncertainty in Estimated Trends Using Gridded Rainfall Data: A Case Study of Bangladesh

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 349 ◽  
Author(s):  
Mohamed Salem Nashwan ◽  
Shamsuddin Shahid ◽  
Xiaojun Wang
Keyword(s):  
Spatial Patterns ◽  
Similarity Index ◽  
Skill Score ◽  
Rainfall Data ◽  
Seasonal Rainfall ◽  
Annual Rainfall ◽  
Global Precipitation Climatology Centre ◽  
Rainfall Trends ◽  
Grid Points

This study assessed the uncertainty in the spatial pattern of rainfall trends in six widely used monthly gridded rainfall datasets for 1979–2010. Bangladesh is considered as the case study area where changes in rainfall are the highest concern due to global warming-induced climate change. The evaluation was based on the ability of the gridded data to estimate the spatial patterns of the magnitude and significance of annual and seasonal rainfall trends estimated using Mann–Kendall (MK) and modified MK (mMK) tests at 34 gauges. A set of statistical indices including Kling–Gupta efficiency, modified index of agreement (md), skill score (SS), and Jaccard similarity index (JSI) were used. The results showed a large variation in the spatial patterns of rainfall trends obtained using different gridded datasets. Global Precipitation Climatology Centre (GPCC) data was found to be the most suitable rainfall data for the assessment of annual and seasonal rainfall trends in Bangladesh which showed a JSI, md, and SS of 22%, 0.61, and 0.73, respectively, when compared with the observed annual trend. Assessment of long-term trend in rainfall (1901–2017) using mMK test revealed no change in annual rainfall and changes in seasonal rainfall only at a few grid points in Bangladesh over the last century.

scholarly journals Multi-Year Mapping of Disturbance and Reclamation Patterns over Tronox’s Hillendale Mine, South Africa with DBEST and Google Earth Engine

Land ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 760
Author(s):  
Sifiso Xulu ◽  
Philani T. Phungula ◽  
Nkanyiso Mbatha ◽  
Inocent Moyo
Keyword(s):  
South Africa ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Google Earth ◽  
Abandoned Mines ◽  
Remote Sensing Technology ◽  
Sensing Technology ◽  
Petroleum Resources ◽  
Google Earth Engine ◽  
The Government

This study was devised to examine the pattern of disturbance and reclamation by Tronox, which instigated a closure process for its Hillendale mine site in South Africa, where they recovered zirconium- and titanium-bearing minerals from 2001 to 2013. Restoring mined-out areas is of great importance in South Africa, with its ominous record of almost 6000 abandoned mines since the 1860s. In 2002, the government enacted the Mineral and Petroleum Resources Development Act (No. 28 of 2002) to enforce extracting companies to restore mined-out areas before pursuing closure permits. Thus, the trajectory of the Hillendale mine remains unstudied despite advances in the satellite remote sensing technology that is widely used in this field. Here, we retrieved a collection of Landsat-derived normalized difference vegetation index (NDVI) within the Google Earth Engine and applied the Detecting Breakpoints and Estimating Segments in Trend (DBEST) algorithm to examine the progress of vegetation transformation over the Hillendale mine between 2001 and 2019. Our results showed key breakpoints in NDVI, a drop from 2001, reaching the lowest point in 2009–2011, with a marked recovery pattern after 2013 when the restoration program started. We also validated our results using a random forests strategy that separated vegetated and non-vegetated areas with an accuracy exceeding 78%. Overall, our findings are expected to encourage users to replicate this affordable application, particularly in emerging countries with similar cases.

scholarly journals Growing Season Precipitation Rather than Growing Season Length Predominates Maximum Normalized Difference Vegetation Index in Alpine Grasslands on the Tibetan Plateau

2020 ◽  
Vol 12 (3) ◽  
pp. 968
Author(s):  
Jiang Wei Wang ◽  
Meng Li ◽  
Guang Yu Zhang ◽  
Hao Rui Zhang ◽  
Cheng Qun Yu
Keyword(s):  
Tibetan Plateau ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Growing Season ◽  
The Tibetan Plateau ◽  
Season Length ◽  
Alpine Grasslands ◽  
Vegetation Productivity ◽  
Growing Season Length ◽  
Growing Season Precipitation

Precipitation and growing season length (GSL) are vital abiotic and biotic variables in controlling vegetation productivity in alpine regions. However, their relative effects on vegetation productivity have not been fully understood. In this study, we examined the responses of the maximum normalized difference vegetation index (NDVImax) to growing season precipitation (GSP) and GSL from 2000 to 2013 in 36 alpine grassland sites on the Tibetan Plateau. Our results indicated that NDVImax showed a positive relationship with prolonged GSL (R2 = 0.12) and GSP (R2 = 0.39). The linear slope of NDVImax increased with that of GSP rather than GSL. Therefore, GSP had a stronger effect on NDVImax than did GSL in alpine grasslands on the Tibetan Plateau.

scholarly journals Analisa Penyebaran Potensi Kekeringan Lahan di Kabupaten Rembang

2020 ◽  
Vol 33 (2) ◽  
Author(s):  
Martza Swastikasari ◽  
Natania Frislya Nanulaitta
Keyword(s):  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Agricultural Land ◽  
Satellite Image ◽  
Infiltration Rate ◽  
High Water ◽  
Rainfall Data ◽  
Water Infiltration ◽  
Central Java ◽  
Water Holding

Kekeringan lahan yang melanda suatu daerah menimbulkan dampak yang besar terhadap produktivitas lahan pertanian. Terjadinya kekeringan ini disebabkan oleh defisit air akibat kurangnya hujan yang jatuh, laju infiltrasi air yang tinggi serta jenis tanaman yang tidak sesuai dengan ketersediaan air.  Untuk meminimalkan dampak yang terjadi akibat kekeringan lahan maka perlu dilakukan antisipasi dengan mengetahui defisit dan surflus air lahan melalui data curah hujan serta kemampuan tanah menahan air (Water Holding Capasity). Oleh sebab itu, dalam penelitian ini penulis mencoba untuk menganalisa penyebaran potensi penyebaran kekeringan di wilayah Kabupaten Rembang Propinsi Jawa Tengah. Parameter yang didapat yaitu interpretasi dari citra satelit lansat 8 (OLI), data statistik Kabupaten Rembang, dan data curah hujan. Didalam penelitian ini juga penulis menggunakan indeks vegetasi NDVI (Normalized Difference Vegetation Index) dan SAVI (Soil-Adjusted Vegetation Index)yang dapat menghasilkan rata-rata luas wilayah potensi kekeringan di masing-masing kecamatan pada Kabupaten Rembang. Land drought that hit a region has a great impact on the productivity of agricultural land. The occurrence of this drought is caused by water deficit due to lack of falling rain, high water infiltration rate and types of plants that are not in accordance with the availability of water. To minimize the impacts caused by land drought, it is necessary to be anticipated by knowing the deficit and land water surfs through rainfall data and the ability of water holding capasity. Therefore in this study the authors try to analyze the spread of potential spread of drought in rembang district of central java province. The parameters obtained are the interpretation of satellite image 8 (OLI), statistical data of Rembang Regency, and rainfall data. In this study, the authors used the NDVI (Normalized Difference Vegetation Index) and SAVI (Soil-Adjusted Vegetation Index) vegetation index which can produce the average of drought potential areas in each sub-district in Rembang district.

scholarly journals Fig. 3. Relation between per capita income and measures of private (A, B) and public (C) green infrastructure, including the normalized difference vegetation index (NDVI) and fractional tree cover. NDVI and tree cover values are expressed as percentage relative differences to respective district municipality means. Data points represent census tracts and are faded to highlight densities.

2021 ◽  
Author(s):  
Zander S Venter ◽  
Charlie M. Shackleton ◽  
Francini Van Staden ◽  
Odirilwe Selomane ◽  
Vanessa A Masterson
Keyword(s):  
South Africa ◽  
Low Income ◽  
Green Infrastructure ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Tree Cover ◽  
Racial Groups ◽  
Public And Private ◽  
Data Points ◽  
Relative Differences

<p>Urban green infrastructure provides ecosystem services that are essential to human wellbeing. A dearth of national-scale assessments in the Global South has precluded the ability to explore how political regimes, such as the forced racial segregation in South Africa during and after Apartheid, have influenced the extent of and access to green infrastructure over time. We investigate whether there are disparities in green infrastructure distributions across race and income geographies in urban South Africa. Using open-source satellite imagery and geographic information, along with national census statistics, we find that public and private green infrastructure is more abundant, accessible, greener and more treed in high-income relative to low-income areas, and in areas where previously advantaged racial groups (i.e. White citizens) reside.</p>

scholarly journals Identification of South African Bermudagrass Germplasm with Shade Tolerance

HortScience ◽  
2015 ◽  
Vol 50 (10) ◽  
pp. 1419-1425 ◽  
Author(s):  
Jeffrey C. Dunne ◽  
W. Casey Reynolds ◽  
Grady L. Miller ◽  
Consuelo Arellano ◽  
Rick L. Brandenburg ◽  
...  
Keyword(s):  
South Africa ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Economic Value ◽  
Fertility Treatments ◽  
Turf Quality ◽  
Poor Tolerance ◽  
Adequate Quality ◽  
Added Benefit ◽  
Susceptible Control

Bermudagrass, Cynodon spp. is one of the most commonly grown turfgrass genera in the southern United States having excellent drought tolerance, but poor tolerance to shade. Developing cultivars tolerant to shade would allow bermudagrass to become more prevalent in home lawns or other recreational areas in the southeast, where trees dominate the landscape. In this field study, nine accessions collected from Pretoria, South Africa were evaluated for their ability to grow under shade with varying fertility treatments. These accessions and cultivars ‘Celebration’, ‘TifGrand’, and ‘Tifway’ were evaluated under 0%, 63%, and 80% continuous shade during 2011–12. For both years, significant differences among shade levels, genotypes, and the interaction of the two were observed. As expected, the progression from 0% to 63% to 80% shade reduced normalized difference vegetation index (NDVI), percent turfgrass cover (TC), and turf quality (TQ) readings for all accessions. Some genotypes, however, were able to maintain adequate quality and aggressiveness under 63% shade. ‘Celebration’, WIN10F, and STIL03 performed better than ‘Tifway’ (P ≤ 0.05), the susceptible control. Overall, our results indicate that there are promising genotypes among the bermudagrass materials collected from South Africa. These accessions represent additional sources of shade hardiness to be used in bermudagrass breeding. Furthermore, higher nitrogen fertility provided increased NDVI and TQ in some instances suggesting an added benefit of fertility under low-light conditions. However, the increased economic value attributed to the added inputs associated with these increases is outweighed by the low impacts offered.

Understanding the Resilience of Sal and Teak Forests to Climate Variability Using NDVI and EVI Time Series

2021 ◽  
Vol 67 (2) ◽  
pp. 192-204
Author(s):  
Maneesh Kumar Patasaraiya ◽  
Rinku Moni Devi ◽  
Bhaskar Sinha ◽  
Jigyasa Bisaria ◽  
Sameer Saran ◽  
...  
Keyword(s):  
Minimum Temperature ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Central India ◽  
Annual Rainfall ◽  
Maximum Temperature ◽  
Spatial And Temporal Scales ◽  
Changing Climate ◽  
Tiger Reserve ◽  
Sal Forest

Abstract This study attempts to understand the climatic resilience of two forest types of central India—that is, Tectona grandis (Teak) forest of Satpura Tiger Reserve and Shorea robusta (Sal) forest of Kanha Tiger Reserve—using normalized difference vegetation index (NDVI), enhanced vegetation index (EVI) extracted from MODIS, and climate variable data sets at highest spatial and temporal scales. Teak and Sal forests within the core area of the selected tiger reserves represent the least anthropogenic disturbances, and therefore, the observed changes in NDVI and EVI over the past 16 years could be analyzed in the context of climate change. The correlation analysis between climatic variables (minimum temperature, maximum temperature, mean temperature, and total annual rainfall) and forest response indicators (NDVI/EVI) at seasonal and annual scales revealed that Teak and Sal forests are more sensitive to change in past temperature as compared with rainfall. Also, the changes in NDVI and EVI of Sal forest are correlated more to minimum temperature, and that of Teak forest to maximum temperature. The analysis of sapling girth class of Sal and Teak further revealed that Sal as compared with Teak is more affected because of the changing climate variables of the recent past. The findings of the study will help manage forests more efficiently in the context of changing climate.

scholarly journals Does Vegetation Parameterization from EO NDVI Data Capture Grazing induced Variations in Species Composition and Biomass in Semi-Arid Grassland Savanna?

2014 ◽  
Vol 11 (11) ◽  
pp. 16309-16347
Author(s):  
J. L. Olsen ◽  
S. Miehe ◽  
P. Ceccato ◽  
R. Fensholt
Keyword(s):  
Time Series ◽  
Species Composition ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Net Primary Production ◽  
Regional Scale ◽  
Grazing Intensity ◽  
Vegetation Productivity ◽  
Modis Ndvi ◽  
Coarse Resolution

Abstract. Most regional scale studies of vegetation in the Sahel have been based on Earth observation (EO) imagery, due to the limited number of sites providing continuous and long term in situ meteorological and vegetation measurement. From long time series of coarse resolution normalized difference vegetation index (NDVI) data a greening of the Sahel since the 1980s has been identified. The greening appears highly related to a general increase in rainfall following the severe droughts of the 1970s and 80s. In the same time period the region has experienced a drastic population boom and a resulting increase in numbers of livestock. However, it is poorly understood how commonly applied remote sensing techniques reflect the extensive influence of grazing on natural rangeland vegetation. This paper analyses time series of parameterized Moderate Resolution Imaging Spectroradiometer (MODIS) NDVI data by comparison with data from the Widou Thiengoly test site in northern Senegal. Field data include grazing intensity, vegetation productivity, and species composition from sizeable areas suitable for comparison with moderate – coarse resolution satellite imagery. It is established that sampling plots excluded from grazing have higher Net Primary Production (NPP) and different species composition as compared to plots under controlled grazing or communal grazing. The seasonal small integrated NDVI, derived using absolute thresholds to estimate start and end of growing seasons, is identified as the parameter most strongly related to vegetation productivity for all grazing regimes. However plot-pixel comparisons demonstrates how the NDVI/biomass relationship changes due to grazing induced variation in annual plant species composition and the NDVI values for grazed plots are only slightly lower than the values observed for the ungrazed plots. Hence, average biomass in ungrazed plots since 2000 was 0.93 t ha−1, compared to 0.51 t ha−1 for plots subjected to controlled grazing and 0.49 t ha−1 for communally grazed plots, but the average integrated NDVI values for the same period were 1.56, 1.49, and 1.45 for ungrazed, controlled and communal respectively, i.e. a much smaller difference. This indicates that a grazing induced development towards less standing crop biomass and limited ability to turn additional water in wet years into biomass can cause neutral or even increasing NDVI trends over time. It is important to note that these findings are based on limited data and needs to be further verified, as it ultimately indicates that the greening of Sahel could partly be an indicator of increasingly intensified grazing.

scholarly journals The Midsummer Dry Spell’s Impact on Vegetation in Jamaica

2010 ◽  
Vol 49 (7) ◽  
pp. 1590-1595 ◽  
Author(s):  
Theodore L. Allen ◽  
Scott Curtis ◽  
Douglas W. Gamble
Keyword(s):  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Tropical Rainfall Measuring Mission ◽  
Early Summer ◽  
Annual Rainfall ◽  
Dry Spell ◽  
Moderate Resolution ◽  
Rainfall Reduction ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
The Impact

Abstract The annual rainfall pattern of the intra-Americas sea reveals a bimodal feature with a minimum during the midsummer known as the midsummer dry spell (MSD). A first attempt is made to examine the impact of the MSD on vegetation through a normalized difference vegetation index (NDVI) analysis in Jamaica. Tropical Rainfall Measuring Mission rainfall estimates and NDVI derived from the Terra Moderate Resolution Imaging Spectroradiometer highlight a consistent MSD feature in both rainfall and vegetative vigor. Spatial variation of this MSD NDVI response is evident throughout Jamaica, with the strongest relationship between the rainfall reduction and NDVI decline throughout the southern portions of Jamaica including the area of major domestic food production. In all years except 2005 there is a notable reduction from early-summer NDVI to midsummer NDVI in this agricultural region. However, the lagged vegetative response undergoes clear interannual variation and is affected by other forcings besides rainfall, such as brush fires and extreme wind.

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