ORCHIDEE_FireFrag

This version of ORCHIDEE has been used in "Road fragment edges enhance wildfire incidence and intensity, while suppressing global burned area" by Simon P.K. Bowring, Wei Li, Florent Mouillot, Thais Rosan and Philippe Ciais, and has been accepted for publication in Nature Communications (2024).

Abstract

Landscape fragmentation is empirically correlated with both increases and decreases in wildfire burned area (BA). These different directions-of-impact are not mechanistically understood. Here, road density, a land fragmentation proxy, is implemented in a CMIP6 coupled land-fire model, to represent fragmentation edge effects on fire-relevant environmental variables. Fragmentation caused modelled BA changes of over ±10% in 16% of [0.5°] grid-cells. On average, more fragmentation decreased net BA (-1.5% globally), as observed empirically. However, in recently-deforested tropical areas, fragmentation drove empirically-consistent BA increases of over 20%. Globally, fragmentation-driven fire BA decreased with increasing population density, but was a hump-shaped function of it in forests. In some areas, fragmentation-driven decreases in BA occurred alongside higher-intensity fires, suggesting the decoupling of fire severity traits. This mechanistic model provides a starting point for quantifying policy-relevant fragmentation-fire impacts, whose results suggest future forest degradation may shift fragmentation from net global fire inhibitor to net fire driver.

Code access

• See the version on the webinterface here : ​https://forge.ipsl.fr/orchidee/browser/branches/publications/ORCHIDEE_FireFrag
• Extract it on a terminal as follow, type anonymous as password:

  svn co --username anonymous svn://forge.ipsl.fr/orchidee/branches/publications/ORCHIDEE_FireFrag ORCHIDEE