Bringing worlds together - Combining Madingley and LPJmL models in an African regional case study

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The Madingley model is unique in its ability to mechanistically model whole terrestrial ecosystems. However, its focus has been animal ecology. Complex animal ecosystems are usually embedded and essentially build on the presence of terrestrial vegetation, nutrient and water cycling processes. Changes in the latter necessarily will have impacts on the functioning of animal ecosystems

The representation of plants in Madingley is crude, and misses much of the ecological complexity and ecosystem functioning that is already being addressed in the more established domain of terrestrial vegetation modeling. Here we use the unique strengths of Madingley – capable of modeling terrestrial ecosystem, trophical networks and stability and viability of ecosystems under constant increasing human pressure and well established dynamic global vegetation models and water balance model LPJmL (“Lund-Potsdam-Jena managed Land”).

LPJmL model computes the establishment, growth and productivity of natural and agricultural plant types, carbon, nitrogen, phosphorus and water fluxes, and response to climatic conditions and human interferences such as irrigation, land use change and groundwater withdrawal. Natural and agricultural vegetation is represented by various plant functional types (PFTs), characterized by different physiological, morphological, phenological, bioclimatic and fire-response attributes. Agricultural vegetation (currently 12 common crop types) can be either rainfed or irrigated. Simulations can be made of past, present and future climates. Outcomes of LPJmL modeling also provide a basis for evaluating the potential for rain-fed farming, e.g., for poor subsistence farmers to increase their yields, producing food also for local market and potential income raising, and thus, will make it possible to identify water scarcity-driven poverty and malnutrition hot-spots, which may culminate in risk of conflict and/or urban, trans-country or international migration.

In an East African cases study we will couple the animal component of Madingley with LPJmL. In so doing, we will improve the representation of natural vegetation and include agricultural vegetation for the first time into Madingley, as well as incorporate the feedback from animals on plants (e.g. grazing pressure) in LPJmL.

By 2030, East African society faces a major global challenge: to eradicate hunger and secure sustainable food for all (Sustainable Development Goal, SDG, 2) whilst also ensuring sustainable terrestrial ecosystems and halting biodiversity loss (SDG 15). Bringing together this discrepancy is a global challenge.

Africa currently has greatest rate of population growth of any continent: the population is projected to more than double in size to 2.9 billion by 2050. This growth will necessarily result in increased demands on the environment, for example, conversion of land for food production and the extraction of water. The challenge of sustainably meeting the demands of a rapidly growing population will be exacerbated by climate change

East Africa is also characterized by a particularly large diversity of species and ecosystems. The escalation of anthropogenic pressures resulting from population growth is likely to impact upon biodiversity and thus upon the capacity of ecosystems to provide the goods and services (e.g. nutrient cycling or provision of clean water) on which society ultimately depends.

The East Africa region is economically unique in combining a substantial agricultural sector, both arable and pastoral, with a substantial sector of the economy supported by tourism linked to the diversity and iconic status of its native fauna. However these economic demands come into conflict, which will increase in a future dominated by global change, if the environmental resources of the region are not managed effectively. Already, 30-40 % of African forests and savannas have been converted to cropland, pasture and urban areas.

But the effects of natural resource degradation feeds back on society; it endangers food production in this mostly semi-arid region with regular droughts. Ongoing decline in natural resources in East Africa has also led to increasing social group conflicts over limiting resources such as water or land. Resultant wars and conflicts have led to refugee movements to other countries or migration into the cities and urbanization.

To plan for a sustainable future decision-makers rely on decision support tools - approaches that help them forecast the effects of policies and test economic and societal scenarios to determine the effects they will have on the natural world. However, at present there are no tools that integrate agriculture, both arable and pastoral, and natural ecosystems, comprising of plants and animals, in a coupled socio-ecological system. Thus decision-makers have limited capacity to explore how to balance the competing, simultaneous demands of food provision and sustainable ecosystems.

State of the art models of terrestrial plant (agricultural and natural) dynamics and terrestrial animals exist but have never been integrated.

By dynamically bringing together outputs from Madingley and LPJmL allows us to:

1. to make a step change in our ability to forecast coupled socio-ecological systems by integrating state of the art vegetation and ecosystem modeling with anthropogenic pressures of climate change and agriculture.
2. To use this novel modeling framework to explore the sustainability of future scenarios of socio-economic development in Africa, focusing on the East Africa region, and what these might therefore mean for the resilience of these socio-ecological systems under global change.

In achieving these, this project will provide a tool that is generally applicable, i.e. can be applied in all regions of the world, and will enable decision-makers and development scientists to better address questions at the agriculture, ecosystems, development nexus. The project will demonstrate this, for East Africa, by exploring strategies for meeting agricultural demands whilst ensuring sustainability of ecosystem functioning (for example water cycling and nutrient cycling) and of economically and socially important biodiversity (the abundance of large, iconic, wild animals such as elephants, zebra or big cats).

Written by Ingo Fetzer (http://www.stockholmresilience.org/contact-us/staff/2012-09-05-fetzer.html). Ingo Fetzer is a researcher in Systems Stability at the Stockholm Resilience Centre