The extent of European sub-alpine grasslands and their associated ecosystem services are decreasing due to woody plant encroachment. Commonly used methods of woody vegetation suppression like prescribed burning or clearcutting usually cause little damage to belowground bud-banks, offering poor results against re-sprouting shrubs. In this study, we assessed the effects on vegetation and soil properties of two mechanical shrub removal methods for restoring sub-alpine grasslands colonized by the re-sprouting shrub Rosa sp. in the Central Spanish Pyrenees: a commonly used method based on clearcutting (Clearcutting); and a non-previously assessed method based on pulling shrubs off the soil to remove both the aerial and belowground bud-banks (Uprooting). We set a parallel experiment to test whether or not clustering Rosa sp. debris generated in Uprooting (which held many mature fruits) at certain grassland locations may promote colonization of new grassland spots by Rosa sp. seedlings. By the end of the study period, vegetation composition and structure was more similar to the reference grassland in Uprooting than in Clearcutting. Indeed, woody vegetation cover was 71 % smaller in Uprooting than in Clearcutting three years after shrub removal. Nevertheless, by the end of the study period, chemical and microbiological soil properties were slightly more similar to the reference grassland in Clearcutting than in Uprooting. Additionally, the results of our study showed that clustering unusually high number of mature fruits of Rosa sp. at certain grassland locations increased shrub seedling colonization in comparison with other areas of the reference grassland, indicating that operational planning needs to take into account shrub phenology. In conclusion, our work showed that Uprooting may be a useful tool for land managers aiming to restore sub-alpine grasslands colonized by re-sprouting shrubs, though it is advisable using it for scatter shrub patches to prevent significant medium to long-term soil disturbance at landscape scale.

In the Low Arctic, a warming climate is increasing rates of permafrost degradation and altering vegetation. Disturbance associated with warming permafrost can change microclimate and expose areas of ion-rich mineral substrate for colonization by plants. Consequently, the response of vegetation to warming air temperatures may differ significantly from disturbed to undisturbed tundra. Across a latitudinal air temperature gradient, we tested the hypothesis that the microenvironment in thaw slumps would be warmer and more nutrient rich than undisturbed tundra, resulting in altered plant community composition and increased green alder (Alnus viridis subsp. fruticosa) growth and reproduction. Our results show increased nutrient availability, soil pH, snow pack, ground temperatures, and active layer thickness in disturbed terrain and suggest that these variables are important drivers of plant community structure. We also found increased productivity, catkin production, and seed viability of green alder at disturbed sites. Altered community composition and enhancement of alder growth and reproduction show that disturbances exert a strong influence on deciduous shrubs that make slumps potential seed sources for undisturbed tundra. Overall, these results indicate that accelerated disturbance regimes have the potential to magnify the effects of warming temperature on vegetation. Consequently, understanding the relative effects of temperature and disturbance on Arctic plant communities is critical to predicting feedbacks between northern ecosystems and global climate change.