Soil Cultivation on Afforestation Sites

Soil Cultivation on Afforestation Sites

Today I joined Dr Jens Haufe. Jens got his Masters in forestry and PhD in forest sciences at the Dresden university of technology in Germany. He now works as a forest researcher in the UK.

Strategically planted trees in a previously not forested area in Israel 

Afforestation is the establishing of forests where there was no previous forest. 
Soil cultivation is the rearranging of soil. 

Why is soil cultivation done in forestry?

it is used to improve survival rates of transplants and conditions for tree growth by temporarily altering soil conditions. 

Typical composition of soil (varies by soil type) 

The main reasons for soil cultivation:

• Reduce weed competition

• Improve soil aeration 

• Provide nutrients for transplants

• Break compacted soil layers - prevents shallow roots

Potential negative impacts of soil cultivation: 

• Damaging of natural soil arrangement

• Destruction of rearrangement of soil microbiome

• Can reduce water retention too much, preventing water storage needed for tree growth 

There is some debate on whether soil cultivation is needed at all, with some considering it to be outdated and potentially more harmful than good. Its use may change in upcoming years.

Despite organic matter making up only 5% of soil composition, it is the only source of carbon. 

Why is it important to plant more trees?

Forests accumulate carbon up to equilibrium point - roughly 1ha of forest stores 15tonnes of carbon dioxide per year (varying on conditions and species). 

The standard unit of measuring the damage a greenhouse gas does is carbon dioxide equivalent (CO2e).

UK woodlands are estimated to store 3.781 billion tonnes of carbon dioxide equivalent. By planting more trees we can reduce the carbon in the atmosphere, this is called carbon sequestration.  

The most important Greenhouse gases:

• Carbon Dioxide (CO2) - accounts for 86% of UK greenhouse gas emissions (2014)

• Methane (CH4) - 28x more damaging than carbon dioxide

• Nitrous Oxide (N2O) - 265x more damaging than carbon dioxide

• Hydrofluorocarbons (HFL)

• Perfluorocarbons (PFL)

• Sulpher hexafluoride (SF6) 

Conclusion

The use of soil cultivation in forestry is becoming more and more debated, with many questioning the its benefits and drawbacks, but it may be necessary if we wish to plant trees in certain soils. 

Afforestation is increasing in necessity if we wish to combat climate change, as well as, become more sustainable in our wood use.

Further deforestation will increase atmospheric CO2 which will only accelerate climate change.  Because of this, it is becoming increasingly necessary for us to reach an equilibrium between tree planting and deforestation, which may be achieved through afforestation. 

Student reflection

I love forests and want more trees planted, but the specifics of soil composition and maintenance are found to be less than appealing. Career direction is still uncertain, however, this may deter me from applying for a masters in forestry. 

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