Forest ecology and Biogeochemical cycles

Evaluating the potential benefit from large-scale forestation action as a climate-change mitigation strategy
Shani Rohatyn

Through the process of photosynthesis, forests, among other vegetation types, assimilate atmospheric CO2 and store it in their body and soil. Afforestation, reforestation, and forest management, increase carbon sinks, and are considered useful tools for mitigating climate change. Forestry activities change also land surface properties and further enhance important surface biophysics, including albedo and surface roughness. Forests generally tend to have lower albedo (the fraction of incident sunlight reflected back to space) than that of the ecosystem they replace. The decreasing albedo results in higher absorption of solar radiation, and exerts a positive radiative forcing on climate (i.e., warming).

The contrasting biogeochemical and biophysical forests’ effects on climate is increasingly recognized in the climate change and terrestrial ecosystems research community, yet it has not been implemented into climate policies for climate change mitigation programs. These effects vary largely among regions and forest types, yet quantification of these contrasting effects in specific locations has rarely been attempted. Thus, our aim is to identify potential land for forestation actions of afforestation/reforestation at a global scale, with maximum benefit for climate change mitigation.

My research goals are; first, to identify a quantitative index to be used as a ‘common currency’ for comparing the value of biochemical (carbon sequestration) and biophysical effects (albedo and others) of forestation (afforestation or reforestation) on climate. Second, to map the differential value of different regions for forestation in the context of climate-change mitigation at global scale. I will account for both biochemical and biophysical processes, considering region-specific soil, climate, vegetation type and density. And last, to estimate the overall global benefit of forestation to climate change mitigation, and compare it to other mitigation strategies, including emission reduction and energy efficiency.

Projected climate change may have devastating effects on humans worldwide, and current mitigation plans (mostly emission reduction) may not suffice. Thus, it is of utmost importance to evaluate additional means, such as large-scale forestation, particularly since this approach was never evaluated as a whole. The general aim of our study is to evaluate the potential of large-scale forestation action, including reforestation and afforestation, as a climate-change mitigation strategy.