How does land-use change from tropical forest to agriculture affect root dynamics? Fine root dynamics within land-use change from forest to agriculture: A pan-tropical review.
Systematic review protocol:CIFOR Working Paper 200, Dec. 2015
Globally, roots contribute up to half of the carbon cycled annually in forests, and they may account for approximately one-third of global annual net primary production. As deforestation pressures continue to threaten a growing number of tropical forests, root dynamics and their roles in the carbon cycle are a critical area of research.
The biggest driver of tropical deforestation is clearing forest for agriculture, causing huge amounts of greenhouse gas (GHG) emissions. Forest carbon conservation schemes, such as Reducing Emissions from Deforestation and Forest Degradation (REDD+), suggest that rewarding forest users for protecting forest could be an effective means to reduce GHG emissions. Following this trend, current research on how land-use change affects the carbon cycle focuses on GHG measurements and the quantification of aboveground biomass carbon stocks. Although root dynamics and their influence on the belowground carbon cycle are frequently studied in forests or agriculture, studies on how land-use change affects root dynamics are lacking. Identifying the knowledge gaps in how land-use change affects root dynamics could result in this topic being prioritized in carbon cycle research and thus help to accurately quantify GHG emissions from land-use change.
Current data on root dynamics in tropical forests contain huge variation. For example, fine root production rates range from 75 to 2175 g m-2 year-1. Species compositions, soil nutrient content, temperature and precipitation among others are different between study sites, which explains some of the variation in fine root dynamics. However, even if different methods (e.g. sequential coring, in-growth cores and minirhizotrons) are used to estimate root dynamics on the same site, they produce different results. This review aims to analyze and quantify the variances associated with the different methods stated above to improve root dynamic estimation. The objectives of this review are to:
- identify the differences in root dynamics between forests and agriculture;
- assess the differences between the methods used to quantify root dynamics.