Analysis of Postfire Vegetation Dynamics of Mediterranean Shrub Species Based on Terrestrial and NDVI Data

Abstract

The present study offers an analysis of regeneration patterns and diversity dynamics after a wildfire, which occurred in 1993 and affected about 7000 ha in southern Spain. The aim of the work was to analyze the rule in the succession of shrub species after fire, relating it to the changes registered in the Normalized Difference Vegetation Index (NDVI). Fractional vegetation cover was recorded from permanent plots in 2000 and 2005. NDVI data related to each time were obtained from Landsat images. Both data sets, from fieldwork and remote sensing, were analyzed through statistical and quantitative analyses and then correlated. Results have permitted the description of the change in plant cover and species composition on a global and plot scale. It can be affirmed that, from the seventh to the twelfth year after the fire, the floristic composition within the burned area remained unchanged at a global level. However, on a smaller scale (plot level), the major shrub species, Ulex parviflorus, Rosmarinus officinalis, and Cistus clusii, underwent significant changes. The regeneration dynamics established by these species conditioned plant species composition and, consequently, diversity indexes such as Shannon (H) and Simpson (D). The changes recorded in the NDVI values corresponding to the surveyed plots were highly correlated with those found in the regrowth of the main species. Areas dominated by U. parviflorus in a senile phase were related to a decrease in NDVI values and an increase in the number of species. This result describes the successional dynamics; the dryness of the main colonizer shrub species is allowing the regrowth and re-establishment of other species. Within the study area, NDVI shows sensitivity to postfire plant cover changes and indirectly expresses the diversity dynamics.

Landscape – wildfire interactions in southern Europe: Implications for landscape management

“…In other burned areas, highly flammable tussock grasses (some of which are alien) can replace locally dominating woody species, resulting in increasing frequencies of very large and intense fires (Grigulis et al, 2005;Vilà et al, 2001). Several studies have confirmed that the recovery rate of scrub cover after fire was quite rapid, often exceeding the pre-fire biomass amount (Hernandez-Clemente et al, 2009;Roder et al, 2008;Viedma et al, 1997). Simulation models such as FATELAND and BROLLA have shown an increase in shrublands as a response to increased fire frequency, creating a state of successional stagnation which may enhance the positive shrub-fire feedback (Pausas, 1999;Pausas and Lloret, 2007) (Fig.…”

Advances in Remote Sensing of Post-Fire Vegetation Recovery Monitoring - A Review

“…Usually, these index transforms are based on thorough field calibration. Only few studies incorporated a substantial number of field plots to calibrate and validate the VI approach (Shaw et al 1998;Bisson et al 2008;Clemente et al 2009;Jacobson 2010;Segah et al 2010;van Leeuwen et al 2010;Vila and Barbosa 2010;Veraverbeke et al 2011bHernandez-Clemente et al 2009). Figure 1 presents an example of the relationship between the NDVI and field estimates of vegetative cover which was used to model post-fire vegetation cover in the burned area.…”

Retrospective analysis of two northern California wild-land fires via Landsat five satellite imagery and Normalized Difference Vegetation Index (NDVI)

“…Previous research has noted the possibility of full regeneration of forest type vegetation to pre-fire conditions in a time period of thirteen years following a major wild-land fire [40]. Changes in species composition and initial increases in species abundance have been observed in the first stages of forest recovery [51], on temporal scale of one to three years, followed by lower levels in subsequent years [41,52]. However, increased levels of wild-land fire severity have been shown to decrease overall species abundance [53].…”

“…A significantly larger and darker post-fire burn scar was observed for areas affected by the BLC (Figure 3), which indicates greater vegetation damage and potential landscape change, and may be attributed to the prior abundance of woody vegetation, typically observed in this mixed conifer area [22,34]. Vegetation types and post-fire vegetation regrowth dynamics are believed to have been contributing factors leading to less noticeable BHC burn scar and increased NDVI recovery (Figures 3(e) and (h)) [22,40,41]. Results of the NDVI post-fire image comparisons between complexes, however, may have been influenced by differences in NDVI recovery time, because in efforts aimed at consistency, collection of post-fire NDVI images for both complexes were derived from a further dated singular post-fire image, then transformed into NDVI grey-scale images.…”

“…In contrast, one-year pre-and post-wild-land fire multitemporal image of BHC showed the entire area encompassed in a light blue hue (Figure 3(b)), which indicates some form of vegetation re-growth [22]. This positive re-growth may possibly be linked to increased recovery due to the elasticity of species typical of savannah grassland type vegetation in relation to fire disturbance [22,40,41]. Both multi-temporal images of BHC displayed noticeable levels of landscape change.…”