Abstract
Experimental plots were established on severely eroded land surfaces in Iceland in 1999 to study the rates and limits of soil carbon sequestration during restoration and succession. The carbon content in the upper 10 cm of soils increased substantially during the initial eight years in all plots for which the treatments included both fertilizer and seeding with grasses, concomitant with the increase in vegetative cover. In the following five years, however, the soil carbon accumulation rates declined to negligible for most treatments and the carbon content in soils mainly remained relatively constant. We suggest that burial of vegetated surfaces by aeolian drift and nutrient limitation inhibited productivity and carbon sequestration in most plots. Only plots seeded with lupine demonstrated continued long-term soil carbon accumulation and soil CO2flux rates significantly higher than background levels. This demonstrates that lupine was the sole treatment that resulted in vegetation capable of sustained growth independent of nutrient availability and resistant to disruption by aeolian processes.
Highlights
Interest in the carbon cycle and the various sources and sinks of rapidly exchangeable carbon often focuses on aboveground biomass of specific biomes, most typically tropical to temperate forests
The work by Aradottir et al [22] focused on the vegetative patterns in the experimental plots, the increase in vegetative cover, and found that all plots that had been seeded with grasses as part of the treatment showed rapid increases in cover for the first few years
The experimental plots at Geitasandur that were established in 1999 to study land reclamation and carbon sequestration were resampled in 2012 and the results compared with earlier studies [20, 22]
Summary
Interest in the carbon cycle and the various sources and sinks of rapidly exchangeable carbon often focuses on aboveground biomass of specific biomes, most typically tropical to temperate forests This approach ignores the much greater mass of carbon stored in soils globally, estimated at over 2300 Gt C [1]. High latitude settings store considerable SOC, with the 144 Gt estimated in tundra soils amounting to 6% of the global SOC pool, a mass nearly equal to that estimated for boreal forest or deciduous temperate forest soils [1]. This may, be an underestimate as a recent study increased the numbers for high latitude soils by almost an order of magnitude [2]. A better understanding of the size of the high latitude SOC pool and the rates of exchange with the atmosphere is required to enhance our ability to model anticipated changes in global climate
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