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Drought Influence on Forest Plantations in Zululand, South Africa, Using MODIS Time Series and Climate Data

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dc.contributor.author Xulu, Sifiso
dc.contributor.author Peerbha, Kabir
dc.contributor.author Gebreslasie, Michael
dc.contributor.author Ismail, Riyad
dc.date.accessioned 2020-01-24T12:27:35Z
dc.date.available 2020-01-24T12:27:35Z
dc.date.issued 2018-08-30
dc.identifier.citation Xulu, S., Peerbhay, K., Gebreslasie, M. and Ismail, R., 2018. Drought influence on forest plantations in Zululand, South Africa, using MODIS time series and climate data. Forests, 9(9), p.528. en_US
dc.identifier.issn 1999-4907
dc.identifier.uri https://doi.org/10.3390/f9090528
dc.identifier.uri http://hdl.handle.net/10530/1984
dc.description Peer reviewed article published under Forests Journal, Volume 9 Issue 9 en_US
dc.description.abstract South Africa has a long history of recurrent droughts that have adversely affected its economic performance. The recent 2015 drought has been declared the most serious in 26 years and impaired key agricultural sectors including the forestry sector. Research on the forests’ responses to drought is therefore essential for management planning and monitoring. The effects of the latest drought on the forests in South Africa have not been studied and are uncertain. The study reported here addresses this gap by using Moderate Resolution Imaging Spectroradiometer (MODIS)-derived normalized difference vegetation index (NDVI) and precipitation data retrieved and processed using the JavaScript code editor in the Google Earth Engine (GEE) and the corresponding normalized difference infrared index (NDII), Palmer drought severity index (PDSI), and El Niño time series data for KwaMbonambi, northern Zululand, between 2002 and 2016. The NDVI and NDII time series were decomposed using the Breaks for Additive Seasonal and Trend (BFAST) method to establish the trend and seasonal variation. Multiple linear regression and Mann–Kendall tests were applied to determine the association of the NDVI and NDII with the climate variables. Plantation trees displayed high NDVI values (0.74–0.78) from 2002 to 2013; then, they decreased sharply to 0.64 in 2015. The Mann–Kendall trend test confirmed a negative significant (p = 0.000353) trend between 2014 and 2015. This pattern was associated with a precipitation deficit and low NDII values during a strong El Niño phase. The PDSI (−2.6) values indicated severe drought conditions. The greening decreased in 2015, with some forest remnants showing resistance, implying that the tree species had varying sensitivity to drought. We found that the plantation trees suffered drought stress during 2015, although it seems that the trees began to recover, as the NDVI signals rose in 2016. Overall, these results demonstrated the effective use of the NDVI- and NDII-derived MODIS data coupled with climatic variables to provide insights into the influence of drought on plantation trees in the study area. en_US
dc.language.iso en en_US
dc.publisher MDPI en_US
dc.subject drought en_US
dc.subject NDVI en_US
dc.subject NDII en_US
dc.subject precipitation en_US
dc.subject El Niño en_US
dc.subject PDSI en_US
dc.subject forest disturbance en_US
dc.subject Climatology en_US
dc.title Drought Influence on Forest Plantations in Zululand, South Africa, Using MODIS Time Series and Climate Data en_US
dc.type Article en_US

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