Shrub influence on soil moisture, nutrients, temperature and species composition, 2019 - 2020.

Shrubification, the expansion and densification of shrubs, is occurring in arctic and alpine zones across the globe (Myers-Smith et al., 2011)⁠. This alteration is primarily driven by warming temperatures (Elmendorf et al., 2012b, 2012a)⁠, and can have major consequences for the existing vegetation (Anthelme et al., 2007; Pajunen et al., 2011; Venn et al., 2014)⁠ and for nutrient pools (Sturm et al., 2005; DeMarco et al., 2014)⁠ due to the abiotic and biotic effects of shrubs. Shrubs accumulate snow which insulates the ground during the winter and provides more moisture later in the season (Liston et al., 2002)⁠. During the summer, shrubs provide shade and wind protection. Additionally, shrubs can increase the soil nitrogen (N) pool through their high input of plant material into the soil (DeMarco et al., 2014). These small-scale climatic and soil alterations have important consequences for plant community dynamics in the arctic and alpine. References: Anthelme, F., Villaret, J.-C., and Brun, J.-J., 2007: Shrub encroachment in the Alps gives rise to the convergence of sub-alpine communities on a regional scale. Journal of Vegetation Science, 18(3):355–362. DeMarco, J., Mack, M. C., and Bret-Harte, M. S., 2014: Effects of arctic shrub expansion on biophysical vs . biogeochemical drivers of litter decomposition. Ecological Society of America, 95(7):1861–1875. Elmendorf, S. C., Henry, G. H. R., Hollister, R. D., Björk, R. G., Bjorkman, A. D., Callaghan, T. V., Collier, L. S., Cooper, E. J., Cornelissen, J. H. C., Day, T. A., Fosaa, A. M., Gould, W. A., Grétarsdóttir, J., Harte, J., Hermanutz, L., Hik, D. S., Hofgaard, A., Jarrad, F., Jónsdóttir, I. S., Keuper, F., Klanderud, K., Klein, J. A., Koh, S., Kudo, G., Lang, S. I., Loewen, V., May, J. L., Mercado, J., Michelsen, A., Molau, U., Myers-Smith, I. H., Oberbauer, S. F., Pieper, S., Post, E., Rixen, C., Robinson, C. H., Schmidt, N. M., Shaver, G. R., Stenström, A., Tolvanen, A., Totland, Ø., Troxler, T., Wahren, C. H., Webber, P. J., Welker, J. M., and Wookey, P. A., 2012a:. Global assessment of experimental climate warming on tundra vegetation: Heterogeneity over space and time. Ecology Letters, 15(2):164–175. Elmendorf, S. C., Henry, G. H. R., Hollister, R. D., Björk, R. G., Boulanger-Lapointe, N., Cooper, E. J., Cornelissen, J. H. C., Day, T. A., Dorrepaal, E., Elumeeva, T. G., Gill, M., Gould, W. A., Harte, J., Hik, D. S., Hofgaard, A., Johnson, D. R., Johnstone, J. F., Jónsdóttir, I. S., Jorgenson, J. C., Klanderud, K., Klein, J. A., Koh, S., Kudo, G., Lara, M., Lévesque, E., Magnússon, B., May, J. L., Mercado-Díaz, J. A., Michelsen, A., Molau, U., Myers-Smith, I. H., Oberbauer, S. F., Onipchenko, V. G., Rixen, C., Martin Schmidt, N., Shaver, G. R., Spasojevic, M. J., Pórhallsdóttir, P. E., Tolvanen, A., Troxler, T., Tweedie, C. E., Villareal, S., Wahren, C. H., Walker, X., Webber, P. J., Welker, J. M., and Wipf, S., 2012b:. Plot-scale evidence of tundra vegetation change and links to recent summer warming. Nature Climate Change, 2(6):453–457. Liston, G. E., Mcfadden, J. P., Sturm, M., and Pielke, R. A., 2002: Modelled changes in arctic tundra snow, energy and moisture fluxes due to increased shrubs. Global Change Biology, 8(1):17–32.