Projection of vegetation distribution to 1.5 °C and 2 °C of global warming on the Tibetan Plateau

Previous studies have identified vegetation shifts on the Tibetan Plateau in response to climate change. However, the speed and direction of these changes in alpine vegetation are not well understood. To quantify the responses of the distribution of alpine vegetation to global warming of 1.5 °C or 2 °C, BIOME4 was modified using the Penman–Monteith equation to estimate the reference evapotranspiration, and was run with projected climate data under the RCP4.5 and RCP8.5 scenarios. Gradients of temperature (1–5 °C) and precipitation (−30%–30%) were used to examine the sensitivity of changes in the vegetation pattern to climate. This study suggests that forests on the Tibetan Plateau will expand northwestward with climate warming. Among all forest types, the distribution area of broad-leaved forests will show the greatest increase, whereas mixed needle-broad-leaved forests will show the greatest percentage decrease (~45.5%) relative to the baseline period. Climate warming will result in alpine shrub expansion towards the interior of the Tibetan Plateau, with an average center shift of 309 km under the RCP4.5 scenario with a warming of 1.5 °C. A proportion of alpine meadow will be replaced by alpine shrub, causing it to shrink by ~6.8% under RCP4.5 with a warming of 1.5 °C and by ~15.5% under RCP8.5 with a warming of 2 °C. We conclude that all vegetation types on the Tibetan Plateau are susceptible to a warming climate. Increasing temperatures will move the vegetation boundaries northwestward and this trend will be enhanced by increases in precipitation. Understanding the response of vegetation patterns to warming will facilitate better strategies for carbon storage management.