Carbon Storage in Restored Forests is Species and Age Dependent

by Stephen Johnson

Deforestation in tropical rainforests is a significant and growing conservation concern, and for good reason: as well as harboring high levels of biodiversity, tropical forests are estimated to store 59% of global terrestrial carbon. The capacity of woody plants to store carbon, which constitutes 50% of their biomass, makes them an indispensible consideration in the effort to mitigate global climate change. Of course, forests can’t store carbon if they don’t exist. In the past 14 years alone, more than 100 million hectares of tropical forest have been lost—an area greater than Texas and Arizona combined. This continued destruction has prompted interest in the ability of ecological restoration—replanting forests—to provide ecosystem services such as carbon sequestration and biodiversity habitat. In attempting to rapidly revitalize damaged ecosystems, fast-growing, pioneer species with low wood density are often chosen to replant, though slower-growing, denser species may be required for long-term carbon storage and ecosystem health. To help resolve this question, Shimamoto et al. (2014) examined the biomass accumulation of ten tree species with different ages and growth patterns. By comparing measurements of fast and slow-growing trees in forests of different ages, they were able to determine carbon sequestration through analysis of covariance tests as well as linear and non-linear models. They found that in the first 35-40 years, fast-growing species accumulate the most carbon, but after 40 years, slow-growing species accumulate more carbon, and older forests overall sequester more carbon than young forests. Continue reading