Although West Sumatra is in the wet tropical region of Indonesia, recently climate change impacts on the tree growing.

Irregular rainfall
The graph in the images show that usually the rains continue to increase from july-august onwards. However, for more than 2 years, rains have been very erratic (right graph). The graph shows that after high rainfall, rains stopped, sometimes for more than a month during the rainy season. Dry hot weather with strong winds did not treat all seedlings well.

Fighting climate change by the farmers
Similar to irrigated rice cultivation, farmers have learned not to rely anymore on specific months for planting, but waiting until specific intense rains fall, (the steep curves in the graph on the right). Nowadays, these seem to arrive later, sometimes even November instead of September. So they started planting when the intensity of rain lasted for several days/a week. This would provide enough moisture in the soil to survive for days without rain. However, over the past 2 years it appeared that after planting, rains stopped for sometimes more than a month.

Assisted Natural Regeneration
In areas where we can practice assisted natural regeneration, ANR (presence of imperata grasslands) the thick grasses and weeds cover the soil like a thick blanket preventing evapotranspiration. Moisture remains available for weeks without rain as the moisture cannot evaporate due to the isolation blanket of slowly decaying imperata grasses.

Areas without imperata
Since a few years we are working in even more severely degraded areas, where only ferns grow. ANR does not work, as ferns simply bounce back after pressing. Slashing must be done, so that the slashed biomass can be spread out as a ground cover. However, this ground cover is not as thick as pressed imperata grassland, and decays quickly (see image). Alright if the rains do what they are supposed to do. However, since rains can no longer be predicted, farmers develop innovative ways to keep moisture in the soil in these areas.

Let the weeds grow
Quite a number of farmers understand the benefits of ground cover. To reduce labour costs, they do no longer slash the weedy vegetation around the trees during a dry spell in the rainy season. Instead, they let them grow, so that the ferns and other weeds provide both shade and ground cover as they grow. Farmers only make sure that the weeds do not out compete the growing trees. So they would slash some vegetation near the trees that might outgrow them. In this way, they survive and grow, according to the farmers. In Dutch terms, keep your head above water to prevent drowning.

Not always a dead tree
Over the years we have also noticed that young trees, that look dead, might still come back (see image). A tiny scratch below to see if there is still some green under the bark, will allow most seedlings to combe back alive once rains do come. This and our large nursery, where we keep seedling the entire year round, we are well prepared to replant of whatever is necessary. Intensive monitoring of our field team allows us to estimate potential losses when a rainy season is bad. So far, the worst rainy season we had, showed a 25-30% death-rate. , which is still ok and easy to replace with our stock in the nursery.

Importance of tree growing instead of tree planting
This also shows why we have 5 year contracts with our partners. It can never be about tree planting. Tree growing is a longer term effort to ensure that over 95% of the trees actually survive and grow (our target). During the initial 5 years, our experience is that there is always enough time to catch up with potential losses. Combined with new local knowledge, we are confident that we can beat processes of climate change in our restoration work.