Individual study: Success of transplanted Alpine tundra plants on Niwot Ridge, Colorado, USA
May D.E., Webber P.J. & May T.A. (1982) Success of transplanted Alpine tundra plants on Niwot Ridge, Colorado. Journal of Applied Ecology, 19, 965-976
In the late 1970s, an estimated 12% of alpine tundra in western USA (excluding Alaska) was considered to require vegetation rehabilitation due to damage through physical disturbances. Such sites require re-establishment of plant cover as quickly as possible to prevent further losses, e.g. due to erosion. Unfortunately, vegetation growth is naturally slow in these cold environments with a short growing season. Ways of speeding up the revegetation process might include the use of transplants. This study looked at the success of transplanting plugs of six native alpine tundra species (two dicotyledons and four monocotyledons) within and among six alpine microenvironments in the alpine tundra zone on Niwot Ridge (40°3'N, 105º36'W), Colorado.
Six vegetation units or noda (based on habitat and physiognomy) were identified by clustering 30 sampled stands (each 1 x 10 m) of visually homogeneous vegetation based on plant species cover (percent ground cover in each of 10, 0.1 x 1 m quadrats) and frequency (species presence in each of 10, 1 x 1 m quadrats).
Snow depth and cover were estimated for each stand every 10-14 days from December to June. Length of growing season was defined as the number of days from spring snowmelt when average daily temperatures remained above 0ºC, to 15 September when most species had senesced. Through the season, soil moisture and soil and plant-canopy temperatures were regularly recorded.
Six plant species were selected for their varying growth forms and ecological tolerance: two grasses (Deschampsia caespitosa, Kobresia myosuroides); 2 sedges (Carex rupestris C.pyrenaica); and two herbs (Acomastylis rossii, Sibbaldia procumbens).
Two plots were established, one near an early-melting snowbed and one below a late-melting snowbed. Average-sized individuals were taken from noda where they were common to experimental plots of ‘their own’ and ‘different’ habitats. Transplanting (a total of 1,190 individuals) was undertaken in June and July 1973. Transplants were watered for several weeks to try and minimize early mortality. Transplants were considered established if above-ground growth occurred in subsequent growing seasons.
Transplant success was as follows: D.caespitosa (98%, n = 280); K.myosuroides (83%, n = 70); A.rossii (79%, n = 490); C.pyrenaica (70%, n = 70); S.procumbens (44%, n = 140); and C.rupestris (17%, n = 140).
Results suggest that root form strongly influences establishment success with species having fibrous roots without rhizomes (e.g. D.caespitosa) or other rootstocks and/or well-developed secondary roots being most resilient to transplanting. It was apparent that greater success was not assured by transplanting species into their natural microenvironment.
The success of transplanting for many species varied with microenvironment, primarily due to varying snowcover. The authors suggest it may be possible to enhance transplant success in dry, exposed microenvironments by increasing the amount and duration of snowcover using snowfences.