Exploring Soil Invertebrate Responses to Forest Fires in Margalla Hills National Park (MHNP), Islamabad: An Inquiry into Survival Strategies beneath the Ash

Abstract

A study was conducted to investigate the impact of forest fires on soil invertebrate diversity in the Margalla Hills National Park (MHNP) near Islamabad (33°40 – 33°44 N, 72°55 – 73°20 E), situated in the Murree foothills within an elevation range of 450m to 1500m. The study area experiences a fire season from early April to mid-July annually, resulting in significant biodiversity loss. Data were collected from June 2023 to December 2023, primarily focusing on elevation ranging from 548.64 to 1219.2 m. Eight sampling sites were selected, including Shahdara Top, Ratta Hottar, Kanthla Top, Talharr Top, Trail-3 & Trail-5 Connector, Jabbri, Chera Di Gali, and Saidpur in the study area. During the fire season (April-June), a survey was conducted to compare burnt and unburned areas, revealing that abundant soil invertebrates were also observed in the burnt sites. This occurrence was attributed to the migration of predatory soil invertebrates from unburned areas, where they fed on dead insects. A total of 1211 specimens representing 57 different taxa were recorded, with 302 specimens from 33 taxa in the burnt area and 909 specimens from 57 taxa in the unburned area. The species diversity index was 2.88 for the burnt area, classified as 'Not good'. In contrast, the unburned area exhibited a species diversity index of 3.54, classified as 'Good.' Similarly, species evenness was higher in the unburned area. Post-fire season surveys (referred as Winter Season) revealed a significant decline in soil biodiversity, attributed to Alien Invasive Plant Species (AIPS), soil compaction, and dormancy of invertebrates, creating unfavorable habitats for soil biota. A comparison of diversity between summer and winter seasons in the eight sampling sites with burnt areas showed variations in the sites with Trail 3 and 5 Connector exhibiting the highest diversity in summer and Chera Di Gali ranking highest in winter due to dormancy stages of invertebrates of the order Coleoptera, Geophilida and Scolopendromorpha. Common orders observed in burnt sites included Aranea, Coleoptera, Dictyoptera, Gastropods, Hemiptera, Homoptera, Hymenoptera, and Orthoptera. In contrast, unburned sites showed abundance in orders like Aranea, Coleoptera, Diptera, Geophilida, Gastropods, Hemiptera, Homoptera, Haplotaxids, Lepidopterans, Scolopendromorpha, and Zygentoma. Certain species occurred in both burnt and unburned sites, belonging to orders including Aranea, Dictyoptera, Diptera, Gastropods, Geophilida, Hemiptera, Hymenoptera, Isoptera, and Orthoptera. Forest fires limit data collection for invertebrates, plant biodiversity, and macrofauna. Effective conservation and management of soil invertebrate species in MHNP, Islamabad, require immediate and comprehensive preventive measures by relevant authorities such as IWMB and CDA Islamabad.