In 1980-1982, six transplant gardens were established along a latitudinal gradient in interior Alaska from Eagle Creek, AK, in the south to Prudhoe Bay, AK, in the north (Shaver et al. 1986) .Three sites, Toolik Lake (TL), Sagwon (SAG), and Prudhoe Bay (PB) are north of the continental divide and the remaining three, Eagle Creek (EC), No Name Creek (NN), and Coldfoot (CF), are south of the continental divide. Each garden consisted of 10 individual tussocks transplanted back to their home-site, as well as 10 individuals from each of the other transplant sites (n = 10; 6 populations x 6 sites x 10 replicates = 360 total individuals).

All gardens were censused in 2010. For a haphazardly chosen subsample of tillers ( n = 12) on each tussock, the total number of green leaves was counted and the length of the two longest leaves was measured from the top of the sheath. There were some tussocks with fewer than 12 tillers, in which case we measured all those alive. Old leaves that were initiated the previous year were identified by a dark band with dead tissue above it, whereas new leaves had no such band. A tiller size index was calculated by multiplying the length of the longest leaf by the total number of green leaves (usually 2, 3 or 4). This tiller index is highly correlated with tiller mass (Shaver, Fetcher & Chapin 1986).

Bennington CC, Fetcher N, Vavrek MC, Shaver GR, Cummings KJ, McGraw JB (2012) Home site advantage in two long-lived arctic plant species: results from two 30-year reciprocal transplant studies. Journal of Ecology 100:841-851

Shaver GR, Fetcher N, Chapin FS (1986) Growth and flowering in Eriophorum vaginatum - Annual and latitudinal variation. Ecology 67:1524-1535

Notes:
Funding for this research was provided by National Science Foundation grant ARC-0908936 with additional support from NSF-BSR-9024188.
Tiller size data are incorporated in Bennington et al. 2012