Mortality Mapping of Pinus wallichiana in Nanda Devi Biosphere Reserve: A UNESCO World Heritage Site in India

In Earth Systems and Environment
Peer-reviewed Article
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This study addresses the concerning mortality of Pinus wallichiana (blue pine), a crucial timber species in the northwestern
Himalayas, specifically within the Nanda Devi Biosphere Reserve (NDBR)––a UNESCO world heritage site in India.
Hazard prediction mapping was carried out during the study period (2018–2021) using the MaxEnt program and supervised
classification algorithm over the Sentinel dataset. The mortality was observed in Kaga, Kosha, Farkiya, Dronagiri, Garpak,
Ruing, Jhelum, and Bampa, en route from Surai Thota to Jumma and then to Malari (Chamoli, NDBR). Both biotic
and abiotic factors contributed to the significant mortality of blue pine. The MaxEnt model showed an AUC value range of
0.889 ± 0.141 (current)–0.988 ± 0.008 (mortality), where the Jackknife test elaborated that the factor of environmental precipitation
(Percentage Contribution (PC) = 34.30% and Permutation Importance (PI) = 1.1%) contributed most, followed by
the seasonality of temperature (Bio 4; PC = 25.90% and PI = 31.20%) and highest temperature for the warmest month (Bio
5; PC = 22.40% and PI = 40.30%). Additionally, the precipitation was indicated by the response curves ranged from 138 to
154 mm with a maximum at 145 mm (p = 0.88), the slope at 2.5° (p = 0.97) and 9° (p = 0.91), and wind speed ranged from
1.76 to 2.00 ms−
1 with a maximum (p = 0.92) at 1.85 ms−
1. Along the altitudinal gradient, the mortality maps showed ~ 10 km2
affected area, which is 6.3% of the total occurrence of blue pine in the NDBR, with the majorly (~ 4 km2)
lying between 3001
and 3250 m amsl, i.e., monsoon-influenced subarctic climate (Dwc) following the Köppen-Geiger Climatic Classification.
Maps generated using an ensemble approach helps in understanding risks of natural hazards, and useful for surveillance and
monitoring by inferring the spread direction in due course. Studying the current and future health of forest trees in NDBR
can further assist in decision-making, in situ and ex situ conservation, and long-term planning to timely mitigate the blue
pine mortality disaster.

Maneesh S.
Pawan Kumar
Rajendra K.
Harish S.