Resilience of the Central Indian Forest Ecosystem to Rainfall Variability in the Context of a Changing Climate

Understanding the spatio-temporal pattern of natural vegetation helps decoding the responses to climate change and interpretation on forest resilience. Satellite remote sensing based data products, by virtue of their synoptic and repetitive coverage, offer to study the correlation and lag effects of rainfall on forest growth in a relatively longer time scale. We selected central India as the study site. It accommodates tropical natural vegetation of varied forest types such as moist and dry deciduous and evergreen and semi-evergreen forests that largely depend on the southwest monsoon. We used the MODIS derived NDVI and CHIRPS based rainfall datasets from 2001 to 2018 in order to analyze NDVI and rainfall trend by using Sen’s slope and standard anomalies. The study observed a decreasing rainfall trend over 41% of the forests, while the rest of the forest area (59%) demonstrated an increase in rainfall. Furthermore, the study estimated drought conditions during 2002, 2004, 2009, 2014 and 2015 for 98.2%, 92.8%, 89.6%, 90.1% and 95.8% of the forest area, respectively; and surplus rainfall during 2003, 2005, 2007, 2011, 2013 and 2016 for 69.5%, 63.9%, 71.97%, 70.35%, 94.79% and 69.86% of the forest area, respectively. Hence, in the extreme dry year (2002), 93% of the forest area showed a negative anomaly, while in the extreme wet year (2013), 89% of forest cover demonstrated a positive anomaly in central India. The long-term vegetation trend analysis revealed that most of the forested area (>80%) has a greening trend in central India. When we considered annual mean NDVI, the greening and browning trends were observed over at 88.65% and 11.35% of the forested area at 250 m resolution and over 93.01% and 6.99% of the area at 5 km resolution. When we considered the peak-growth period mean NDVI, the greening and browning trends were as follows: 81.97% and 18.03% at 250 m and 88.90% and 11.10% at 5 km, respectively. The relative variability in rainfall and vegetation growth at five yearly epochs revealed that the first epoch (2001–2005) was the driest, while the third epoch (2011–2015) was the wettest, corresponding to the lowest vegetation vigour in the first epoch and the highest in the third epoch during the past two decades. The study reaffirms that rainfall is the key climate variable in the tropics regulating the growth of natural vegetation, and the central Indian forests are dominantly resilient to rainfall variation

Spatio-Temporal Forest Change Assessment Using Time Series Satellite Data in Palamu District of Jharkhand, India

Free availability of time-series satellite data enabled the current study to quantify decadal macro-variations (i.e., trend and percent change) in vegetation vigour in the forested environment of Palamu district based on 11 years (2001 to 2011) of fortnightly data of Moderate Resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI; 250 m). Further, Landsat ETM+ data of year 2001 and 2011 were also used to extract micro-level changes and as a validation reference. The inter-year comparison about standard anomalies revealed an alarming situation about persistent stress in the vegetation, especially after 2008. However, the degradation rate is slow as per anomaly frequency but steadily increasing after 2008. The study estimated that there is a loss of 293 km(2) forest which is close to the FSI estimate of 333 km(2). The current study provides a quick mechanism to reveal the spatial pattern of temporal changes in the forested region with reliable and reproducible methods