Leaf phenology amplitude derived from MODIS NDVI and EVI: Maps of leaf phenology synchrony for Meso‐ and South America

Gerard, F.; George, Charles; Hayman, Garry; Chavana‐Bryant, Cecilia; Weedon, Graham P.

doi:10.1002/gdj3.87

Cited by 22 publications

(16 citation statements)

References 44 publications

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“…NDVI has been frequently used for assessment of spectral phenology (e.g. Fu et al, 2014;Gerard et al, 2020), and was in our study the most reliable VI across sensors for characterization of phenological traits. The Landsat Tasseled Cap Transformation derived TCA performed similarly and portrayed shorter and delayed seasons.…”

Section: Discussionmentioning

confidence: 79%

Phenological characterization of Fagus sylvatica L. in Mediterranean populations of the Spanish Central Range with Landsat OLI/ETM+ and Sentinel-2A/B

2020

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The Spanish Central Range hosts some of the southernmost populations of Fagus sylvatica L. (European beech). Recent cartography indicates that these populations are expanding, going up-streams and gaining ground to oak forests of Quercus pyrenaica Willd., heather-lands, and pine plantations. Understanding the spectral phenology of European beech populations—which leaf flush occurs earlier than other vegetation formations—in this Mediterranean mountain range will provide insights of the species recent dynamics, and will enable modelling its performance under future climate oscillations. Intra-annual series of 211 Landsat OLI/ETM+ images, acquired between April 2013-December 2019, and 217 Sentinel-2A/B images, acquired between April 2017-December 2019, were employed to characterize the spectral phenology of European beech populations and five other vegetation types for comparison in an area of 108000 ha. Vegetation indices (VI) including the Normalized Difference Vegetation Index (NDVI) and Tasseled Cap Angle (TCA) from Landsat, and the NDVI and Enhanced Vegetation Index (EVI) from Sentinel-2 were retrieved from sample pixels. The temporal series of these VI were modelled with Savitzky-Golay and double logistic functions, and assessed with TIMESAT software, enabling the parametric characterization of European beech spectral phenology in the area with the start, length, and end of season, as well as peak time and value. The length of beech phenological season was similar when portrayed by Landsat and Sentinel-2 NDVI time series (214 and 211 days on average for the common period 2017-2019) although start and end differed. Compared with NDVI counterparts the TCA season started and peaked later, and the EVI season was shorter. Sentinel-2 NDVI peaked higher than Landsat NDVI. The European beech had an earlier (21 days on average) start of season than competing oak forests. Joint analysis of data from the virtual constellation Landsat/ Sentinel-2 and calibration with field observations may enable more detailed knowledge of phenological traits at the landscape scale.

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Section: Discussionmentioning

confidence: 79%

Phenological characterization of Fagus sylvatica L. in Mediterranean populations of the Spanish Central Range with Landsat OLI/ETM+ and Sentinel-2A/B

2020

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“…The Savitzky-Golay filter was also used to reduce noise and rebuild the NDVI time series. The utility of the NDVI has been largely evaluated in the Amazon Basin (Huete et al, 2002;Xu et al, 2011;Hilker et al, 2014Hilker et al, , 2015Maeda et al, 2016;Zhao et al, 2017;Arias et al, 2020), including the western Amazon (Espinoza et al, 2016;Gerard et al, 2020).…”

Section: Land Cover Types Ndvi Dataset and Deforestation Mapmentioning

confidence: 99%

On the Hydroclimate-Vegetation Relationship in the Southwestern Amazon During the 2000–2019 Period

Gutierrez-Cori

Espinoza

et al. 2021

Front. Water

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The southern Amazonia is undergoing a major biophysical transition, involving changes in land use and regional climate. This study provides new insights on the relationship between hydroclimatic variables and vegetation conditions in the upper Madeira Basin (~1 × 106 km2). Vegetative dynamics are characterised using the normalized difference vegetation index (NDVI) while hydroclimatic variability is analysed using satellite-based precipitation, observed river discharge, satellite measurements of terrestrial water storage (TWS) and downward shortwave radiation (DSR). We show that the vegetation in this region varies from energy-limited to water-limited throughout the year. During the peak of the wet season (January-February), rainfall, discharge and TWS are negatively correlated with NDVI in February-April (r = −0.48 to −0.65; p < 0.05). In addition, DSR is positively correlated with NDVI (r = 0.47–0.54; p < 0.05), suggesting that the vegetation is mainly energy-limited during this period. Outside this period, these correlations are positive for rainfall, discharge and TWS (r = 0.55–0.88; p < 0.05), and negative for DSR (r = −0.47 to −0.54; p < 0.05), suggesting that vegetation depends mainly on water availability, particularly during the vegetation dry season (VDS; late June to late October). Accordantly, the total rainfall during the dry season explains around 80% of the VDS NDVI interannual variance. Considering the predominant land cover types, differences in the hydroclimate-NDVI relationship are observed. Evergreen forests (531,350 km2) remain energy-limited during the beginning of the dry season, but they become water-limited at the end of the VDS. In savannas and flooded savannas (162,850 km2), water dependence occurs months before the onset of the VDS. These differences are more evident during extreme drought years (2007, 2010, and 2011), where regional impacts on NDVI were stronger in savannas and flooded savannas (55% of the entire surface of savannas) than in evergreen forests (40%). A spatial analysis reveals that two specific areas do not show significant hydroclimatic-NDVI correlations during the dry season: (i) the eastern flank of the Andes, characterised by very wet conditions, therefore the vegetation is not water-limited, and (ii) recent deforested areas (~42,500 km2) that break the natural response in the hydroclimate-vegetation system. These findings are particularly relevant given the increasing rates of deforestation in this region.

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“…This region contains a portion of a major city, intensive agriculture, towns, rural homesteads, and forest. For this landscape we extracted human population density as of 2010 (Sorichetta et al, 2015, WorldPop, 2016, and leaf area index (LAI) in 2013 as a proxy for tree cover (Gerard et al, 2020).…”

Section: Empirical Landscapesmentioning

confidence: 99%

“…Second, we apply the model in a specific case study to predict how potential vector-borne disease risk would change with alternative strategies of partial reforestation on a region of mixed urban area and farmland northwest of Bogotá Colombia, once again using a range from extremes of "land-sparing" to "land-sharing". This region has been identified as being within a broader area of high restoration importance (Strassburg et al, 2020), and has recent curated MODIS vegetation indices (e.g., NDVI: Normalized Difference Vegetation Index) available (Gerard et al, 2020). Further, this is a high-elevation region that may experience a higher overall vector-borne disease burden with climate warming (Ryan et al, 2019, Mordecai et al, 2020 In both stages we model the transmission of three mosquito-borne diseases that differ in which landscape features promote transmission, in order to capture the types of tradeoffs that are likely to occur on real landscapes.…”

Section: Introductionmentioning

confidence: 99%

Land-use planning for health: Tradeoffs and nonlinearities govern how land-use change impacts vector-borne disease risk

Kain¹,

MacDonald

Mordecai

et al. 2021

Preprint

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Patterns of land-use can affect the transmission of many infectious diseases with human health implications; yet, applied ecosystem service models have rarely accounted for disease transmission risk. A mechanistic understanding of how land-use changes alter infectious disease transmission would help to target public health interventions and to minimize human risk of disease with either ecosystem degradation or restoration. Here, we present a spatially explicit model of disease transmission on heterogeneous landscapes that is designed to serve as a road map for modeling the multifaceted impacts of land-use on disease transmission. We model the transmission of three vector-borne diseases with distinct transmission dynamics (parameterized using published literature to represent dengue, yellow fever, and malaria) on simulated landscapes of varying spatial heterogeneity in tree cover and urban area. Overall, we find that these three diseases depend on the biophysical landscape in different nonlinear ways, leading to tradeoffs in disease risk across the landscape; rarely do we predict disease risk to be high for all three diseases in a local setting. We predict that dengue risk peaks in areas of high urban intensity and human population density, yellow fever risk peaks in areas with low to moderate human population density and high tree cover, and malaria risk peaks where patchy tree cover abuts urban area. To examine how this approach can inform land use planning, we applied the model to a small landscape to the northwest of Bogot&aacute, Colombia under multiple restoration scenarios. We predict that in an area inhabited by both Aedes aegypti and Ae. albopictus, any increase in overall tree cover would increase dengue and yellow fever risk, but that risk can be minimized by pursuing a large contiguous reforestation project as opposed to many small, patchy projects. A large contiguous reforestation project is also able to both reduce overall malaria risk and the number of malaria hotspots. As sustainable development goals make ecosystem restoration and biodiversity conservation top priorities, it is imperative that land use planning account for potential impacts on both disease transmission and other ecosystem services.

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Leaf phenology amplitude derived from MODIS NDVI and EVI: Maps of leaf phenology synchrony for Meso‐ and South America

Cited by 22 publications

References 44 publications

Phenological characterization of Fagus sylvatica L. in Mediterranean populations of the Spanish Central Range with Landsat OLI/ETM+ and Sentinel-2A/B

Phenological characterization of Fagus sylvatica L. in Mediterranean populations of the Spanish Central Range with Landsat OLI/ETM+ and Sentinel-2A/B

On the Hydroclimate-Vegetation Relationship in the Southwestern Amazon During the 2000–2019 Period

Land-use planning for health: Tradeoffs and nonlinearities govern how land-use change impacts vector-borne disease risk

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