Vegetation Greenness in Northeastern Brazil and Its Relation to ENSO Warm Events

Erasmi, Stefan; Schucknecht, Anne; Barbosa, Marx Prestes; Matschullat, Joerg

doi:10.3390/rs6043041

Cited by 54 publications

(30 citation statements)

References 40 publications

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“…The serial correlation defines how neighboring values in a series depend on each other. This serial correlation is usually used to detect trends in ecological time series [58].…”

Section: Temporal Trend Analysesmentioning

confidence: 99%

Monitoring NDVI Inter-Annual Behavior in Mountain Areas of Mainland Spain (2001–2016)

2018

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Currently, there exists growing evidence that warming is amplified with elevation resulting in rapid changes in temperature, humidity and water in mountainous areas. The latter might result in considerable damage to forest and agricultural land cover, affecting all the ecosystem services and the socio-economic development that these mountain areas provide. The Mediterranean mountains, moreover, which host a high diversity of natural species, are more vulnerable to global change than other European ecosystems. The protected areas of the mountain ranges of peninsular Spain could help preserve natural resources and landscapes, as well as promote scientific research and the sustainable development of local populations. The temporal statistical trends (2001–2016) of the MODIS13Q1 Normalized Difference Vegetation Index (NDVI) interannual dynamics are analyzed to explore whether the NDVI trends are found uniformly within the mountain ranges of mainland Spain (altitude > 1000 m), as well as in the protected or non-protected mountain areas. Second, to determine if there exists a statistical association between finding an NDVI trend and the specific mountain ranges, protected or unprotected areas are studied. Third, a possible association between cover types in pure pixels using CORINE (Co-ordination of Information on the Environment) land cover cartography is studied and land cover changes between 2000 and 2006 and between 2006 and 2012 are calculated for each mountainous area. Higher areas are observed to have more positive NDVI trends than negative in mountain areas located in mainland Spain during the 2001–2016 period. The growing of vegetation, therefore, was greater than its decrease in the study area. Moreover, differences in the size of the area between growth and depletion of vegetation patterns along the different mountains are found. Notably, more negatives than expected are found, and fewer positives are found than anticipated in the mountains, such as the Cordillera Cantábrica (C.Cant.) or Montes de Murcia y Alicante (M.M.A). Quite the reverse happened in Pirineos (Pir.) and Montes de Cádiz y Málaga (M.C.M.), among others. The statistical association between the trends found and the land cover types is also observed. The differences observed can be explained since the mountain ranges in this study are defined by climate, land cover, human usage and, to a small degree, by land cover changes, but further detailed research is needed to get in-depth detailed conclusions. Conversely, it is found that, in protected mountain areas, a lower NDVI pixels trend than expected (>20%) occurs, whereas it is less than anticipated in unprotected mountain areas. This could be caused by management and the land cover type.

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“…The serial correlation defines how neighboring values in a series depend on each other. This serial correlation is usually used to detect trends in ecological time series [58].…”

Section: Temporal Trend Analysesmentioning

confidence: 99%

Monitoring NDVI Inter-Annual Behavior in Mountain Areas of Mainland Spain (2001–2016)

2018

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“…However, satellite-derived vegetation indices are mostly used to interpret changes such as greening or browning of the entire vegetation system without being able to distinguish between the woody and herbaceous contribution to those trends [13][14][15][16]. To date, a few studies have used vegetation indices to detect vegetation components in woodland systems at a sub-pixel level.…”

Section: Introductionmentioning

confidence: 99%

A Phenology-Based Method for Monitoring Woody and Herbaceous Vegetation in Mediterranean Forests from NDVI Time Series

et al. 2015

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Abstract:We present an efficient method for monitoring woody (i.e., evergreen) and herbaceous (i.e., ephemeral) vegetation in Mediterranean forests at a sub pixel scale from Normalized Difference Vegetation Index (NDVI) time series derived from the Moderate Resolution Imaging Spectroradiometer (MODIS). The method is based on the distinct development periods of those vegetation components. In the dry season, herbaceous vegetation is absent or completely dry in Mediterranean forests. Thus the mean NDVI in the dry season was attributed to the woody vegetation (NDVIW). A constant NDVI value was assumed for soil background during this period. In the wet season, changes in NDVI were attributed to the development of ephemeral herbaceous vegetation in the forest floor and its maximum value to the peak green cover (NDVIH). NDVIW and NDVIH agreed well with field estimates of leaf area index and fraction of vegetation cover in two differently structured Mediterranean forests. To further assess the method's assumptions, understory NDVI was retrieved form MODIS Bidirectional Reflectance Distribution Function (BRDF) data and compared with NDVIH. After calibration, leaf area index and woody and herbaceous vegetation covers were assessed for those forests. Applicability for pre-and post-fire OPEN ACCESSRemote Sens. 2015, 7 12315 monitoring is presented as a potential use of this method for forest management in Mediterranean-climate regions.

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“…The trends in precipitation in Mongolia are not spatially uniform and can strongly depend on the period of observation used for climate analysis (Erasmi et al, 2014;Giese et al, 2007). Batima et al (2005) found a negative trend of annual precipitation in the period between 1970 and 2001.…”

Section: Introductionmentioning

confidence: 99%

Climate effects on vegetation vitality at the treeline of boreal forests of Mongolia

et al. 2018

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Abstract. In northern Mongolia, at the southern boundary of the Siberian boreal forest belt, the distribution of steppe and forest is generally linked to climate and topography, making this region highly sensitive to climate change and human impact. Detailed investigations on the limiting parameters of forest and steppe in different biomes provide necessary information for paleoenvironmental reconstruction and prognosis of potential landscape change. In this study, remote sensing data and gridded climate data were analyzed in order to identify main distribution patterns of forest and steppe in Mongolia and to detect environmental factors driving forest development. Forest distribution and vegetation vitality derived from the normalized differentiated vegetation index (NDVI) were investigated for the three types of boreal forest present in Mongolia (taiga, subtaiga and forest-steppe), which cover a total area of 73 818 km 2 . In addition to the forest type areas, the analysis focused on subunits of forest and nonforested areas at the upper and lower treeline, which represent ecological borders between vegetation types. Climate and NDVI data were analyzed for a reference period of 15 years from 1999 to 2013.The presented approach for treeline delineation by identifying representative sites mostly bridges local forest disturbances like fire or tree cutting. Moreover, this procedure provides a valuable tool to distinguish the potential forested area. The upper treeline generally rises from 1800 m above sea level (a.s.l.) in the northeast to 2700 m a.s.l. in the south. The lower treeline locally emerges at 1000 m a.s.l. in the northern taiga and rises southward to 2500 m a.s.l. The latitudinal gradient of both treelines turns into a longitudinal one on the eastern flank of mountain ranges due to higher aridity caused by rain-shadow effects. Less productive trees in terms of NDVI were identified at both the upper and lower treeline in relation to the respective total boreal forest type area. The mean growing season temperature (MGST) of 7.9-8.9 • C and a minimum MGST of 6 • C are limiting parameters at the upper treeline but are negligible for the lower treeline. The minimum of the mean annual precipitation (MAP) of 230-290 mm yr −1 is a limiting parameter at the lower treeline but also at the upper treeline in the forest-steppe ecotone. In general, NDVI and MAP are lower in grassland, and MGST is higher compared to the corresponding boreal forest. One exception occurs at the upper treeline of the subtaiga and taiga, where the alpine vegetation consists of mountain meadow mixed with shrubs. The relation between NDVI and climate data corroborates that more precipitation and higher temperatures generally lead to higher greenness in all ecological subunits. MGST is positively correlated with MAP of the total area of forest-steppe, but this correlation turns negative in the taiga. The limiting factor in the forest-steppe is the relative humidity and in the taiga it is the snow cover distribution. The subtaiga represents a...

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Vegetation Greenness in Northeastern Brazil and Its Relation to ENSO Warm Events

Cited by 54 publications

References 40 publications

Monitoring NDVI Inter-Annual Behavior in Mountain Areas of Mainland Spain (2001–2016)

Monitoring NDVI Inter-Annual Behavior in Mountain Areas of Mainland Spain (2001–2016)

A Phenology-Based Method for Monitoring Woody and Herbaceous Vegetation in Mediterranean Forests from NDVI Time Series

Climate effects on vegetation vitality at the treeline of boreal forests of Mongolia

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