Despite a long‐term human impact, Central and Eastern Europe exhibit patches of steppe ecosystems having the highest plant species diversity worldwide. These unique ecosystems have persisted over millennia even though the local climatic conditions would support the formation of a closed forest. Several sources of disturbances have contributed to the persistence of the forest‐steppe landscape such as grazing, fire events and human impact. These disturbances have been recorded in local erosion rates. To gain a deeper understanding of the soil dynamics we aimed at deciphering the long‐ and short‐term erosion rates and the age of the soil mantle. The steppes in Transylvania, Romania, were studied to find evidence of a Holocene continuity of grasslands. Long‐term (millennia) average erosion rates were determined using meteoric 10Be in soils and in situ 10Be of rock outcrops (scarp). Long‐term rates were also estimated by the percolation theory. Short‐term (last few decades) erosion rates were obtained from 239+240Pu in soils. The soils started to form prior to the Last Glacial Maximum, probably during the Eemian Interglacial. The average, long‐term erosion rates varied between 0.18 and 0.63 t ha−1 yr−1. These rates are slightly elevated compared to expected soil erosion rates. The soils of the Transylvanian Plain formed over a long period and reached a quasi‐steady state (soil production equals denudation) that contributed to the maintenance of a biodiversity‐rich forest‐steppe landscape. The slightly elevated erosion rates are an effect of factors that contributed to the Holocene continuity (fire, grazing) and indicate open rather than a forested character of the landscape during soil development. During the last few decades, the erosion rates increased by a factor of 5–10, with values in the range of 1.31–4.05 t ha−1 yr−1. These large differences are caused by changes in human management of the soils. The biodiversity‐rich forest‐steppe landscapes are now under threat.

<p>Alpine and sub-alpine areas react very sensitive to global climate change and carbon cycling therein has been understudied, so far. A major component of plant litter that is commonly regarded as hardly decomposable is lignin. Consequently, the improved knowledge on degradation of lignin and soil organic carbon in alpine areas is of great importance to better understand their response to climate change. Therefore, we conducted a closed-jar incubation experiment under controlled conditions. <sup>13</sup>C labelled plant litter (above ground litter from <em>Lolium perenne</em>) was added to two different soils from a sub-alpine area, one pasture soil and one forest soil originating from Jaun, Switzerland. To investigate the effect of increasing temperatures, the incubation was conducted under three different temperature regimes (average growing season temperature of 12.5°C, +4°C (16.5°C) and +8°C (20.5°C)) for the period of one year with five consecutive destructive samplings.</p><p>Lignin phenols were extracted using the CuO oxidation method, subsequent sample clean-up and quantification by GC-FID. Compound-specific stable carbon (δ<sup>13</sup>C) isotope composition of the lignin phenols was measured by GC-IRMS.</p><p>For all treatment groups, lignin concentrations decreased over the period of one year. The average decrease across all treatment groups was -22.7%. The decrease was slightly higher for the forest soil (-24.9%) than for the pasture site (-20.5%). No significant difference was observed between the control soil with and without added labelled litter. Average lignin decrease for the pasture soil was highest for the lowest temperature (-27.1%). For the two higher temperature treatments the decreases were identical with -17.1% and -17.3%. For the forest soil, the decrease was highest for a temperature of 16.5 °C (26.9%) and slightly lower for 12.5°C (25.7%). Surprisingly, the lowest decrease was observed for 20.5°C (22.1%).</p><p>The evolution of the <sup>13</sup>C labelled litter signal enables the assessment of the degradation of fresh litter in the soils. For all different soils and incubation temperatures, the amount of litter-derived lignin phenols decreased by more than 50% already within two weeks after litter addition. In the further course of time, the <sup>13</sup>C signal decreased much more slowly but remained considerably different from control soils. A possible explanation for this is a high availability of easily degradable carbon within the litter, providing enough energy to produce enzymes for lignin degradation.</p><p>Over the course of a year, also older lignin in the control samples degraded in a similar range as in the samples with litter addition, with a strong decrease in the initial phase and a slower decomposition in the later phase. This can be explained by the better availability of carbon at the beginning of the experiment and missing fresh litter during the later course.</p><p>Contrary to expectations, the degradation of lignin did not increase with rising temperature. This could be due to a lower temperature optimum of the current microbial community which is adapted to the current sub-alpine temperature regime. A complementary field incubation will show whether and how the laboratory results can be transferred to field conditions.</p><p> </p><p> </p>

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<p>Carbon cycling in alpine soils is prone to changes with temperature increase, for instance because of reduced frost periods (Zierl & Bugmann, 2007). Afforestation throughout the last decades and in future with warming climate and land-use change will influence carbon dynamics. To investigate the climate-driven response of carbon cycling in alpine soils, we conducted a jar incubation experiment under controlled conditions using <sup>13</sup>C-labelled plant material and traced the decomposition of the organic material under different increasing temperature regimes.</p><p>Approximately 20 kg of soil samples were collected from the uppermost 10 cm of a 130-year old tree stand and a pasture site from a sub-alpine afforestation sequence in Jaun, Switzerland. The samples were sieved to 2 mm, roots and stones were removed. 50 g of the soil material was incubated in 2 l glass jars.</p><p>To investigate the degradation of the organic material, dried and cut shoots of <sup>13</sup>C labelled plant material (<em>Lolium perenne</em> L.) were added to the soil samples. Additionally, samples without added plant material were incubated as a control group. The incubation was conducted at three different temperature regimes: 12.5°C (average growing season temperature, weather station by WSL-SLF, 2021), 16.5°C (+ 4°C) and 20.5°C (+ 8°C). Destructive sampling was conducted after 0, 2, 4, 8, and 26 weeks. NaOH traps were exchanged every 3-4 days in the beginning and every 3 weeks during later stages of the experiment to trace the respiration of CO<sub>2</sub> and the <sup>13</sup>C label.</p><p>The measured basal respiration shows a temperature dependence. The values are highest at 20.5°C and subsequently decreased to 16.5°C and 12.5°C with the lowest basal respiration. Surprisingly, the basal respiration of the forest soil is always higher than that of the pasture soil of the same incubation temperature. This partially contradicts previous findings (Nazaries et al., 2015) and might be related to the more resilient microbial community in the forest compared to the pasture soil.</p><p>Litter-induced respiration increased sharply after litter application and then decreased again. The pasture soil shows higher cumulative respiration for each temperature compared to the forest soil incubated at the respective temperature. After the highest litter-induced respiration of the pasture soil at 20.5°C at the beginning, this is surpassed by that of the pasture soil with 16.5°C from about 40 days after the beginning of incubation. This could indicate a temperature optimum of the current soil microbial community closer to 16.5°C rather than to 20.5°C. These initial results indicate a different sensitivity of the soil microbial community and consequently also carbon cycling in alpine soils to future rising temperature depending on vegetation cover.</p><p>Nazaries, L., Tottey, W., Robinson, L., Khachane, A., Al-Soud, W. A., Sørenson, S., & Singh, B. K. (2015). Shifts in the microbial community structure explain the response of soil respiration to land-use change but not to climate warming. <em>Soil Biology and Biochemistry</em>, <em>89</em>, 123–134.</p><p>WSL-SLF (2021), IMIS Weather Station Fochsen-Jaun, <em>WSL, </em>Davos/Switzerland.</p><p>Zierl, B., & Bugmann, H. (2007). Sensitivity of carbon cycling in the European Alps to changes of climate and land cover. <em>Climatic Change</em>, <em>85</em>(1–2), 195–212.</p>