Increased temperature, N and snowpack experiment for north of saddle, 2006 - ongoing.

• Main Authors: Suding, Katharine N, Smith, Jane G, Ashton, Isabel W, Niwot Ridge LTER
• Format: Dataset
• Language: English
• Published: Environmental Data Initiative 2022
• Subjects: Tundra
• Online Access: https://dx.doi.org/10.6073/pasta/7ff039a5d6f3fa5155c0a299a903a00a; https://portal.edirepository.org/nis/mapbrowse?packageid=knb-lter-nwt.13.5

In 2006 we established a global change experiment in the Front Range of the Rocky Mountains to investigate how manipulations of warmer summer temperature, N deposition, and increased snowpack would affect the growth of alpine plants. The experiment was implemented on Niwot Ridge, where shrub cover has expanded by over 400% since 1946 (Formica et al. 2014). We established experimental plots north of the Niwot Ridge saddle, in an area of moist meadow tundra where willow shrub (Salix sp.) patches are present. Within experimental plots, Salix glauca seedlings were transplanted in 2006 and 2007 to test whether changing environmental conditions facilitated shrub survival and growth. In 2007 and 2008, phenological observations were recorded for all (2007) or abundant (2008) species in experimental plots. Measurements of plant species composition and aboveground net primary productivity (ANPP) are also made annually or biennially (ANPP, 2017-onward). In 2021, canopy height and NDVI began being measured annually. In July of 2016, a community transplant experiment was implemented to test whether changing environmental conditions support changes in alpine tundra plant communities. Two species characteristic of (1) dry meadow tundra (Tetraneuris acaulis, Erigeron pinnatisectus), (2) snowbed tundra (Ranunculus adoneus, Saxifraga rhomboidea) and (3) subalpine meadow (Trollius albiflorus, Polemonium pulcherrimum) were transplanted into experimental plots. Survival and growth of transplants was documented annually through 2021.