Examples of how site species matching methodology is applied. 

Certain species have characteristics that make them suitable for certain products or uses and are therefore a preferred choice from a commercial perspective. However, if the available sites to plant these species do not have the requirements that provide optimal growth for that species, then it will not perform successfully, leading to potential losses or crop failure. Below are examples of specific species’ characteristics and where they might do well as a commercial crop.

Eucalyptus grandis

This is a widely grown gum tree that has very good pulping characteristics to produce paper products. It is also suitable to produce saw timber and poles. Because of its market potential it has often been grown in areas that do not meet its specific requirements and so has failed as a crop. Its optimal temperature range is between 16 – 20ºC and does not tolerate frost. It also does not tolerate low moisture conditions, especially over extended periods. It requires fairly deep (greater than 80cm), well-structured soils that do not get waterlogged. In these conditions it grows very well.

Pinus elliottii

This is a widely grown pine species as it is suitable for both saw timber and pulp and paper production. It has a good range of site characteristics, which allow it to be grown on a wide variety of different sites. Its optimal temperature range is between 14 – 24ºC and is moderately frost tolerate. It also tolerates low moisture conditions, even over extended periods. It will grow in shallow (greater than 20cm), poorly structured soils, while tolerating moderately waterlogged conditions.

Cupressus lusitanica

This cypress species produces very good saw timber and so is in demand from a commercial perspective. Its optimal temperature range is between 12 – 22ºC and is moderately frost tolerate. It also tolerates low moisture conditions over periods of 2- 4 months. It requires moderately deep (greater than 50cm), well-structured soils that do not get waterlogged. In these conditions it grows very well.

The Impact of Climate Change

Given the concerns about the potential impact of changes to long-term climate effects, particularly increasing temperatures, two potential scenarios were developed to assess potential changes to species suitability distributions over a 30-year period (to 2050).

The two scenarios were based on a “best-case“ scenario, RCP45, which is based on the assumption that climate mitigation efforts are successful in slowing down the rate of change, while the alternative scenario, a “worst case” scenario, RCP85, is based on the assumption that climate mitigation efforts are unsuccessful in slowing down the rate of change.

The results showed that a small shift in the suitability distribution for those species with higher moisture demands tended towards what are currently cooler areas. In other words, the distributions moved towards cooler areas in response to warming temperatures.

References

Fick S and Hijmans R (2017). WorldClim 2: New 1-km spatial resolution climate surfaces for global land areas. International Journal of Climatology 37: 4302 – 4315

Smith C W (2021) A preliminary forestry site classification of Tanzania based on climate and soils. Internal Company Report  – Forestry Development Trust Tanzania

Trabucco A and Zomer RJ (2018). Global Aridity Index and Potential Evapo-transpiration (ET0) Climate Database v2. CGIAR Consortium for Spatial Information (CGIAR – CSI). Published online, available from CGIAR-CSI GeoPortal at https://cgiarcsi.community.