Contrasting Fire Regimes in a Seasonally Dry Tropical Forest and a Savanna Ecosystem in the Western Ghats, India

Abstract

Tropical dry forests and savannas constitute more than half of all tropical forests and grasslands, but little is known about forest fire regimes within these two extensive types of ecosystems. Forest fire regimes in a predominantly dry forest in India, the Nilgiri landscape, and a predominantly savanna ecosystem in the Sathyamangalam landscape, were examined. Remote sensing data were applied to delineate burned areas, determine fire size characteristics, and to estimate fire-rotation intervals. Belt transects (0.5 ha) were used to estimate forest structure, diversity, and fuel loads. Mean area burned, mean number of fires, and mean fire size per year were substantially higher in the Nilgiri landscape compared to the Sathyamangalam landscape. Mean fire-rotational interval was 7.1 yr in the Nilgiri landscape and 44.1 yr in the Sathyamangalam landscape. Tree (≥10 cm diameter at breast height) species diversity, tree density, and basal area were significantly higher in the Nilgiri landscape compared to the Sathyamangalam landscape. Total fuel loads were significantly higher in tropical dry and moist deciduous forests in the Nilgiri landscape, but total fuel loads were higher in the tropical dry thorn forests of the Sathyamangalam landscape. Thus, the two landscapes revealed contrasting fire regimes and forest characteristics, with more and four-fold larger fires in the Nilgiri landscape. The dry forests and savannas could be maintained by a combination of factors, such as fire, grazing pressures, and herbivore populations. Understanding the factors maintaining these two ecosystems will be critical for their conservation.

Post-Fire Regeneration Status of Tree Species in A

“…Previous studies have reported the fire return interval for STR as 44.1 years (Kodandapani et al 2012) and 2-16 years (Kodandapani 2013). The floristic composition of STR is dominated by A. latifolia, P. emblica, T. grandis and P. marsupium, which is similar to that reported for other tropical dry deciduous forests (Balch et al 2013) including Mudumalai Tiger Reserve (MTR) (Kodandapani et al 2008a, Satyam & Jayakumar 2015.…”

“…The size, frequency, intensity, timing, ignition pattern and ecological effects of fires and post-fire plant regeneration patterns are key features in ecological damage assessments. In India, fire-based regeneration studies have been conducted in the Western Ghats (Mahesh 2005, Kodandapani 2013, Nandita & Sukumar 2015, Central India (Sonali 2002, Sonali & Howe 2003 and Northern India (Munesh et al 2012, Ashish et al 2013. In recent years, using satellite data, studies on fire monitoring have also been carried out in the Mudumalai Tiger Reser ve (Satyam & Jayakumar 2015, Satyam et al 2015, Kerala (Badarinath et al 2012), Bandipur National Park (Somashekar et al 2009), Bhadra Wildlife Sanctuary (Somashekar et al 2008), Andhra Pradesh (Reddy et al 2012), Satna (Rajpoot & Kumar 2013) and Rajasthan (Reddy et al 2009).…”

Functional Traits of Trees From Dry Deciduous “Forests” of Southern India Suggest Seasonal Drought and Fire Are Important Drivers

“…Several analyses of contemporary fire regimes in the subcontinent confirm that dry deciduous "forests" burn much more frequently (fire return intervals range from 1 to 6 years) and extensively (10-50% of these landscapes burn annually) than do other forest types (Kodandapani et al, 2008;Kodandapani, 2013;Srivastava and Garg, 2013;Mondal and Sukumar, 2016;Reddy et al, 2017). Together with the trait comparisons we report in this study, which are consistent with predicted trait differences between mesic savanna and forest species (Ratnam et al, 2011), these data suggest that large tracts of dry deciduous "forests" in this region, characterized by trees in grass-dominated understories, are in fact deciduous "savannas, " where seasonal water-stress and fire are important drivers.…”

Monitoring of fire incidences in vegetation types and Protected Areas of India: Implications on carbon emissions

“…The studies in India have utilised moderate resolution AWiFS and high resolution LISS III data (Kodandapani et al 2004;Somashekar et al 2008;Reddy et al 2009Reddy et al , 2012Reddy et al , 2014Sowmya andSomashekar 2010 Harikrishna andSharma et al 2012;Kodandapani 2013;Sudeesh and Reddy 2013;Saranya et al 2014;Satish and Reddy 2016). Near real-time monitoring of active fires is being carried out by National Remote Sensing Centre and Forest Survey of India using coarse resolution MODIS sensor as a part of Indian Forest Fire Response and Assessment System (NRSA 2006).…”