A vital link: water and vegetation in the Anthropocene

Abstract

Abstract. This paper argues that the interplay of water, carbon and vegetation dynamics fundamentally links some global trends in the current and conceivable future Anthropocene, such as cropland expansion, freshwater use, and climate change and its impacts. Based on a review of recent literature including geographically explicit simulation studies with the process-based LPJmL global biosphere model, it demonstrates that the connectivity of water and vegetation dynamics is vital for water security, food security and (terrestrial) ecosystem dynamics alike. The water limitation of net primary production of both natural and agricultural plantsalready pronounced in many regions -is shown to increase in many places under projected climate change, though this development is partially offset by water-saving direct CO 2 effects. Natural vegetation can to some degree adapt dynamically to higher water limitation, but agricultural crops usually require some form of active management to overcome it -among them irrigation, soil conservation and eventually shifts of cropland to areas that are less water-limited due to more favourable climatic conditions. While crucial to secure food production for a growing world population, such human interventions in water-vegetation systems have, as also shown, repercussions on the water cycle. Indeed, land use changes are shown to be the second-most important influence on the terrestrial water balance in recent times. Furthermore, climate change (warming and precipitation changes) will in many regions increase irrigation demand and decrease water availability, impeding rainfed and irrigated food production (if not CO 2 effects counterbalance this impact -which is unlikely at least in poorly managed systems). Drawing from these exemplary investigations, some research perspectives on how to further improve our knowledge of human-watervegetation interactions in the Anthropocene are outlined.

Climate change impacts on runoff in West Africa: a review

“…There is also an urgent need to take into account the other factors influencing runoff, especially water and land use changes, in order to get a more comprehensive assessment and to guide the elaboration of sound adaptation strategies. This can be achieved through the use of integrated process-based models that simultaneously include the driving processes that link climate, carbon, water and terrestrial vegetation dynamics (Guimberteau et al, 2014;Gerten, 2013).…”

The unfolding water drama in the Anthropocene: towards a resilience‐based perspective on water for global sustainability

“…Improved water productivity would reduce the water required for an adequate diet from 1300 to 1000 m 3 capita −1 year −1 . More countries would therefore be able to meet their national food needs, although large regional differences would remain (Rockström et al , ; Gerten, ). With two thirds of the world population for food security depending on food import to compensate the effect of country water deficit, a fair and efficient system of global trade will be crucial for reducing inequalities in the capacity to sustain local and regional food self‐sufficiency (Costanza et al , ; Fader et al , ).…”

On inclusion of water resource management in Earth system models – Part 1: Problem definition and representation of water demand

“…Nonetheless, it still remains unclear whether increased transpiration efficiency is canceled out by increased transpiration due to increasing biomass and plant growth. More studies, therefore, are required in this direction (see Gerten, 2013). This is a context for which LSMs can offer an ideal platform as they have the explicit modules required for considering dynamic interactions of carbon, vegetation and water -see the discussion of Sect.…”