Climate sensitivity analysis of Potential Natural Vegetation over the Indian monsoon domain using BIOME4

Abstract

Vegetation and Climate have a complex relationship and either one acts as a control to the other. Vegetation model simulations can be employed to investigate this relationship and to check the vegetation responses to a set of climate forcings. We aim to assess the Potential Natural Vegetation maps generated by BIOME4, an equilibrium coupled biogeochemistry model, for India and study the sensitivity of the Potential Natural Vegetation in India to extreme rainfall and temperature forcings. We force temperature, rainfall, other climate parameters and soil parameters to BIOME4 to generate Potential Natural Vegetation covers for India as well as regional Potential Natural Vegetation covers within India. A preliminary comparison between the BIOME4 response to 1901-2020 long term mean monthly forcings with a reference Potential Natural Vegetation cover revealed a 22.65% agreement that indicates significant disparity, which could be explained by: i) The lack of distinction between dry and moist deciduous forests in BIOME4 as well as typical Potential Natural Vegetation reference maps, ii) Overestimated surface runoffs by BIOME4 which would preferably select for shrubs over deciduous forests, iii) Overestimated Net Primary Productivities by BIOME4 when compared with modelled Net Primary Productivity from satellite data which would significantly affect the selection of dominant Plant Functional Types by BIOME4. Extreme rainfall and temperature analysis revealed: i) Extreme rainfall forcings generate a more appreciable vegetation response as opposed to extreme temperature forcings, ii) South-East and North-West India are sensitive, Central and South-West India are impervious, and North-East India is potentially sensitive to extreme rainfall forcings when the threshold approach is employed. Future work could involve the use of Dynamic Global Vegetation Models for the aforementioned study.