Irrecoverable carbon in mountains and the global mitigation potential of agroforestry and increased tree cover in mountain agricultural systems

Agroforestry has many benefits suited to mountain agricultural systems. This paper seeks to understand and quantify the mitigation potential of multifunctional agroforestry systems, and the potential for increased tree cover in mountains. The potential of agroforestry approaches for protecting irrecoverable carbon in mountains providing alternative, sustainable, and biodiversity-friendly livelihood options for local mountain communities is explored. A substantial portion (29%) of global 'irrecoverable carbon' is found in mountains, representing irreplaceable ecosystems, biodiversity, and globally significant ecosystem services, under unprecedented environmental and demographic pressures, and rapidly changing climatic conditions. This 'premium' mountain carbon supports high levels of biodiversity, including many of the last remaining large mammal species on the planet. Increasing tree cover within agricultural landscapes in mountains can provide sustainable, biodiversity-friendly development options that support environmental and biodiversity conservation. Estimates of existing and decadal change of above- and below-ground biomass on agricultural land within mountainous regions are modeled based up IPCC Tier 1 estimates. Two scenarios are evaluated to estimate carbon sequestration potential of increasing tree cover on agricultural land: 1) incremental change and 2) a systemic change to agroforestry. Estimates of above- and below ground biomass carbon were combined with the tree cover analysis to estimate the change in biomass. Global increases (0.5−0.7 PgC for incremental change; 1.1−2.7 PgC for systematic change) highlight the mitigation potential within mountain agricultural systems. A 10% increase in tree cover on all agricultural land within mountain regions is estimated to sequester 3 PgC.