Impact of forest fire on soil seed bank composition in Himalayan Chir pine forest

Abstract

Abstract Aims To explain how plant community copes with a recurring anthropogenic forest fire in Himalayan Chir pine forest, it is important to understand their postfire regeneration strategies. The primary aim of the study was to know: (i) how fire impact soil seed bank composition and (ii) how much soil seed bank composition differs with standing vegetation after the forest fire. Methods Soil samples were collected from burned and adjoining unburned sites in blocks using three layers down to 9 cm depth immediately after a forest fire and incubated in the net-house for seedling emergence. Same sites were revisited during late monsoon/early autumn season to know the species composition of standing vegetation recovered after a forest fire. Important Findings Soil contained viable seeds of >70 species. The average seed bank density was 8417 and 14 217 seeds/m2 in the burned and unburned site, respectively. In both sites, it decreased with increasing soil depth. Overall fire had no significant impact on seed density; however, taking individual layers into consideration, fire had a significant impact on seed density only in the uppermost soil layer. The species richness of soil seed bank and standing vegetation was 73 and 100, respectively (with 35 shared species), resulting in a similarity of about 40%. In contrast, >80% species in soil seed bank was found similar between burned and unburned sites. Further, there were no significant differences in species richness of standing vegetation in burned (87 spp.) and unburned (78 spp.) sites. Our results showed that fire had an insignificant impact on soil seed bank composition and restoration potential of a plant species from seeds. The understory herb and shrub plant community’s ability to form a fire-resistant viable soil seed bank and capable to recover in the postfire rainy season, explains how they reduce the risk of recurring fire damage in maintaining their population.