In parallel with this strong warming trend, one important change in arctic and sub-arctic tundra ecosystems has been an increase in productivity (Guay et al., 2014) where some areas have experienced increases of up to 10 g phytomass m −2 yr −1 in the last 30 years (Epstein et al., 2012). The ‘Arctic Amplification’ of global warming is also predicted to accelerate in the coming decades, further accentuating the contrasts with overall planetary warming (Serreze & Barry, 2011). Northern high latitudes, particularly north of 60° over land, and across the Arctic Ocean, have warmed by between 1–4 ☌ since 1960, and at a rate substantially greater than the global mean (Serreze & Francis, 2006 Hansen et al., 2010 Serreze & Barry, 2011). The expansion of deciduous shrubs onto potentially vulnerable arctic soils with large stores of C could therefore represent a significant positive feedback to the climate system. Growth rates of fungal hyphae increased across the transition from heath to shrub, suggesting that the action of ectomycorrhizal symbionts in the scavenging of organically bound nutrients is an important pathway by which soil C is made available to microbial degradation. Shrub vegetation had the highest respiration rates, suggesting that despite higher rates of C assimilation, C turnover was also very high and less C is sequestered in the ecosystem. We demonstrate that organic horizon soil organic C (SOC org) is significantly lower at shrub (2.98 ± 0.48 kg m −2) and forest (2.04 ± 0.25 kg m −2) plots than at heath plots (7.03 ± 0.79 kg m −2). We sampled soil C stocks, soil surface CO 2 flux rates and fungal growth rates along replicated natural transitions from birch forest ( Betula pubescens), through deciduous shrub tundra ( Betula nana) to tundra heaths ( Empetrum nigrum) near Abisko, Swedish Lapland. We further hypothesize that a shift from ericoid to ectomycorrhizal systems coincident with this vegetation change provides a mechanism for the loss of soil C. Here, we use a ‘space-for-time’ approach to test the hypothesis that a shift from lower-productivity tundra heath to higher-productivity deciduous shrub vegetation in the sub-Arctic may lead to a loss of soil C that out-weighs the increase in above-ground shrub biomass. However significant the increase in carbon (C) contained within above-ground shrub biomass, it is modest in comparison with the amount of C stored in the soil in tundra ecosystems. For more information or to schedule an appointment, please visit our website.Climate warming at high northern latitudes has caused substantial increases in plant productivity of tundra vegetation and an expansion of the range of deciduous shrub species. Clinics held on the 2nd Thursday of the month and 4th Thursday of the month.
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You can attend the clinic to get advice about how to proceed with an appeal to the Court of Appeals. Unemployment Appeal Legal Advice Clinic - service for people who have already had a hearing with the Unemployment Law Judge and have also requested reconsideration and it has been denied.
There is no income-qualification required for attendance. This is a brief advice clinic for people who are representing themselves. In addition, we offer two clinics for those working on appeals: General Appeals Self-Help Clinic - held on the 3rd Thursday of the month.
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