| 1. |
- Abbott, Benjamin W., et al.
(author)
-
Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire : an expert assessment
- 2016
-
In: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 11:3
-
Journal article (peer-reviewed)abstract
- As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%-85% of permafrost carbon release can still be avoided if human emissions are actively reduced.
|
|
| 2. |
- Keuper, Frida, et al.
(author)
-
Carbon loss from northern circumpolar permafrost soils amplified by rhizosphere priming
- 2020
-
In: Nature Geoscience. - : Springer Science and Business Media LLC. - 1752-0894 .- 1752-0908. ; 13, s. 560-565
-
Journal article (peer-reviewed)abstract
- As global temperatures continue to rise, a key uncertainty of climate projections is the microbial decomposition of vast organic carbon stocks in thawing permafrost soils. Decomposition rates can accelerate up to fourfold in the presence of plant roots, and this mechanism-termed the rhizosphere priming effect-may be especially relevant to thawing permafrost soils as rising temperatures also stimulate plant productivity in the Arctic. However, priming is currently not explicitly included in any model projections of future carbon losses from the permafrost area. Here, we combine high-resolution spatial and depth-resolved datasets of key plant and permafrost properties with empirical relationships of priming effects from living plants on microbial respiration. We show that rhizosphere priming amplifies overall soil respiration in permafrost-affected ecosystems by similar to 12%, which translates to a priming-induced absolute loss of similar to 40 Pg soil carbon from the northern permafrost area by 2100. Our findings highlight the need to include fine-scale ecological interactions in order to accurately predict large-scale greenhouse gas emissions, and suggest even tighter restrictions on the estimated 200 Pg anthropogenic carbon emission budget to keep global warming below 1.5 degrees C.
|
|
| 3. |
- Pluchon, Nathalie, et al.
(author)
-
Recent paludification rates and effects on total ecosystem carbon storage in two boreal peatlands of Northeast European Russia
- 2014
-
In: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 24:9, s. 1126-1136
-
Journal article (peer-reviewed)abstract
- Forest and peatland ecosystems constitute the two major carbon pools in the boreal region. We assess the evolution in total storage and partitioning of ecosystem carbon following recent paludification of forest into peatland at two sites in Northeast European Russia. Based on radiocarbon dating of basal peat and quantification of total ecosystem carbon storage, our results show that paludification rates and its consequences for carbon storage vary significantly between sites. A peatland expanding on ground with steeper slopes has experienced a slow lateral advance in recent times, about 2.6 m on average per century, whereas a peatland in flatter terrain has expanded much more rapidly, about 35 m on average per century. The total ecosystem carbon storage (sum of phytomass, top soil organics or peat, and 30 cm of underlying mineral soil) showed a long-term trend toward increased ecosystem C storage following the replacement of forest (mean value = 20.8 kg C/m(2), range = 13.0-43.4 kg C/m(2)) by peatland (>100 kg C/m(2) in the deepest peat deposits). However, the transitional stage in which the forest is replaced by the margin of the peatland results in a short-term decrease of carbon stored in the ecosystem with a mean loss of 7.5 kg C/m(2). After the initiation of a peatland through paludification, a period of decades to centuries of peat accumulation is needed to compensate for the initial loss of carbon. In the short term, an intensification of the paludification process could lead to a loss of carbon stored in the boreal region.
|
|
