In the course of evolution, many fruit tree species like apple, pear, cherry, plum, and peach have evolved in the mountain regions of Central Asia. Many scientists claim this for walnut evolution as well. In southern Kyrgyzstan, there is the world’s largest area of naturally grown walnut (mixed with other wild fruit species) forests. At the boundaries, walnut trees are integrated into crop land and hay meadows as agroforestry systems.

Walnuts from the walnut forests and walnut trees in the agrarian landscape there are a major source of income for people in and around Arstanbop, which is the central village of that region. But trees are over aging and walnut yields are decreasing. Due to a logging ban, trees must not be cut and regrowth of young trees is largely inhibited by over-grazing. Afforestation of new walnut forests has not been successful, as suitable land is occupied by other land uses and people cannot afford to wait a couple of years until the trees bear fruits. Therefore, planting walnut trees in new agroforestry systems was propagated by several donor projects, including GIZ’s project Community-based management of walnut forests and pasture in South of Kyrgyzstan (https://www.giz.de/en/worldwide/29911.html). Funded by this very project, ICRAF and Eberswalde University for Sustainable Development investigated the costs and benefits as well as cash flows associated to a range of potential crop/vegetable/fruit – walnut tree agroforestry systems.

The results show that starting new tree – crop plantations does barely yield an income. In contrast, cutting some older trees, selling the timber, and start with young walnut trees plus crops does yield an income. The former barely makes money, because fencing costs are very high. Cutting some trees for their timber allows farmers to start off with some money, which allows them to cover fencing costs and bridge low income period before the walnut trees bear fruits.

Another part of ICRAF’s involvement was to select suitable mother trees against the expected impact of climate change. The major issue in this regard is late frost events, which destroy the flowers and consequently the harvest. Such late frosts events occur every few years. But in the course of climate change, average spring temperatures are expected to rise, which will trigger earlier flowering times. The late frost risk is not expected to be reduced. While today in most years walnut trees do not flower before late frosts, trees will tend to flower earlier and earlier and therefore more and more often before late frosts.