Saturday, August 11, 2012

Concept Discussion: What is Forest Agronomy?

I listened to an interesting podcast a few weeks ago and just wanted to share what I learned by listening to "Wissenschaft im Brennpunkt" which translates into "Science in Focus". Today's topic: What is forest agronomy?

Following is a partial transcript and summary of this podcast.



To start the discussion, in many parts of the Western world, forestry and agriculture are currently often separated. Trees grow in the forest and crops on the field. The modern agriculture depends on order. So foresters and farmers often don't interact with each other. Forest agronomy is simply the idea of using the same areas to do both. In other words, forest agronomy is about planting the right group of trees within agricultural areas.

This is actually not a new idea but often forgotten in modern agriculture. Although trees were actually part of the traditional agricultural landscape as part of a meadow with scattered fruit trees, or as a welcome place to escape the sun on a pasture. But in an industrial agricultural landscape, trees often do not seem to fit because they would disturb big industrial machines.

The podcast mentioned that strip mining of brown coal often leaves vast areas of bare earth behind. Wind and rain lead to erosion and very depleted soils. Only weeds are able to grow in such areas. Other more plants with higher demands on the soil just subside. In Lausitz, an area in Germany, efforts were made to re-cultivate such an area by planting trees (poplar, and rubinia) that would be harvested every 3-4 years for energy. The researchers found that the planting of trees quickly lead to the accumulation of fertile soil. Out of the success of combining re-cultivation of soil with profit via harvesting of tree plantations for energy, the thought for an forest-agronomy model was born.

In various research cooperatives with farmers in Lausitz since, the introduction of rows of trees between the different fields has led to a measurable decrease in wind speeds. Combined with an extensive root system that creates a more lose soil structure, erosion can be significantly reduced. Trees have the added benefit of producing additional soil each fall when the leaves drop to the floor. The combination of these effects increases the capacity of the soil to to absorb water. As a result, water does not just flood the fields and end up in the ditch but more is absorbed and kept in the soil. As a result, nitrogen and phosphorous fertilizer are not washed out of the soil as quickly but are kept on the field longer. Lastly, reduced wind speeds also help to keep the soil moister longer.

Forest agronomy has also been found to be helpful in mountainous or hilly areas where wind may be less of an issue but erosion through water flowing along the sides of a hill is. Trees here help retain nutrients along the rows of trees planted. Here rows of sometimes rare trees or fruit trees can be planted. The trees themselves could be harvested profitably because properly maintained trees can produce high quality wood that would sell for a lot of profit. The problem with this kind of approach is that the investment horizon for growing such trees is 50-60 years which is a much longer investment horizon than what the typical farmer thinks off.

According to the podcast, these benefits would be especially useful for poor farmers in tropical areas where combining conservation farming with planting fertilizer trees such as acacia trees could help these farmers prepare for the effects of the the global climate disruptions will bring. If you know German, you will be able to watch a short video that talks about the benefit of forest agronomy in tropical areas.


Ackern unter Bäumen from Gerd Pasch on Vimeo.

Personal Take-Home Message

Trees, therefore, are an investment into the next generation. Frameworks that would support this kind of development should therefore be encouraged because combining forestry and agriculture can have many synergistic effects that would lead to higher productivity for farmers than if forestry and agriculture were just kept separately. In light of the increased use of conversion of biomass to products, these lines of thoughts could be even more important in tomorrow's bio-based economy.

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