Plantations sequester less carbon than natural forests

Plantations sequester less carbon than natural forests according to a new study recently published in the open access journal PLoS ONE.

Yiqi Luo from the University of Oklahoma and fellow researchers conducted a meta-analysis of 86 experimental studies comparing plantations and their natural forest counterparts.

They found that the total ecosystem carbon stock in plants and soils was 28% lower in plantations. While it is unclear exactly why plantations sequester less carbon the researchers found that a number of other related variables were also lower in plantations.

Natural forests had greater net primary production, litterfall, rate of soil respiration, fine root biomass, soil C concentration, soil microbial C concentration, and soil available N, P and K concentrations.

These findings have important implications for global strategies towards halting climate change by increasing carbon sequestration. International programs are being developed that may reward countries for establishing plantations to offset CO2 emissions.

However, as these study findings indicate, replacing natural forests with plantations would actually decrease carbon sequestration. Furthermore, establishing plantations on former agricultural land may have less of an impact on increasing carbon sequestration than restoring natural forests.

Of course, plantations also provide forest products to society and those benefits also need to be taken into consideration.

Furthermore, the authors concede some potential methodological issues - for example, the study sites were not randomly distributed across the forested regions of the world - and therefore they advise that more research is needed. 

Nonetheless the researchers found that the patterns observed did not change regardless of a number of forest characteristics including stand age, stand type, study region, or whether the trees were native or exotic.

Therefore the authors write, "Our findings argue against the replacement of natural forests by the plantations as a measure of climate change mitigation."

--by Rob Goldstein

Liao, C., Luo, Y., Fang, C., & Li, B. (2010). Ecosystem Carbon Stock Influenced by Plantation Practice: Implications for Planting Forests as a Measure of Climate Change Mitigation PLoS ONE, 5 (5) DOI: 10.1371/journal.pone.0010867