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Individual study: Spacing and competition between planted native grass plugs and existing native perennial grasses at a prairie restoration site in the Agate Desert, Oregon, USA

Published source details

Huddleston R.T. & Young T.P. (2004) Spacing and competition between planted grass plugs and preexisting perennial grasses in a restoration site in Oregon. Restoration Ecology, 12, 546-551


A study was undertaken to assess the effects of established Lemmon's needlegrass Achnatherum lemmonii (a native perennial) on planted plugs of two native perennial bunchgrasses at a prairie restoration site in the Agate Desert (42°25′N, 122°52′W), Oregon, northwest USA.

Vegetation was similar across experimental plots, being dominated by non-native annual grasses (primarily soft brome Bromus hordeaceus) and forbs for many decades, and grazed by cattle.
At a nursery, local seed of native bluebunch wheatgrass Pseudoroegneria spicata and Idaho fescue Festuca idahoensis was planted on 25 August 1999 in 5 x 5 x 13 cm soil-filled plastic containers. On 31 October the resultant plugs were planted at 6, 12 of 18 cm from established A. lemmonii bunchgrasses and also in plots without A. lemmonii (16, 1 x 5 m plots).
Plug condition, herbivory and gopher activity in the plot areas were monitored throughout the experiment. On 10 and 14 June 2000, basal diameter and tiller height were remeasured and flowering culms produced by each plug counted.

Plug survival was high in all plots (average > 98%) despite some herbivory on several and extensive gopher activity throughout the area. Plugs planted at 6 cm from established grasses had significantly lower growth and reproduction (around 50% less flowering culms) than plugs planted at 18 cm and those not planted in the vicinity of A. lemmonii.
The results suggest that inter-planting distances of 18 cm were sufficient to greatly reduce competitive effects on newly planted plugs, at least during early establishment.
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