Document: STE-3-34-70

A field test of the effect of climate change on Poa sandbergii.

LINK, S.O.* ¹, H.BOLTON, JR. ² and J.L.SMITH ³

Washington State University at Tri-Cities, Richland, WA 99352 USA ¹
Pacific Northwest National Laboratory, Richland, WA 99352 USA ²
Washington State University, Pullman, WA 99164 USA ³

Abstract:
The effect of climate change on Poa sandbergii was investigated in the field. Poa sandbergii is a small perennial bunchgrass common in the intermountain west. Cores of intact P. sandbergii and soils were transplanted between two elevations in 1994. At each site control cores of the population at the site were included in the study. The lower elevation (347 m) site represents a warmer (12.5 centigrade average January maximum) and dryer (22.4 cm/year) climate while the upper elevation (884 m) site represents a cooler (8.0 centigrade average January maximum) and wetter (27.2 cm/year) climate. The sites are about 5 km apart. Observations were taken in 1999. There was no effect of transplanting on shoot biomass in either population. Shoot biomass for the lower population at the lower site (3.30 grams per square meter) was significantly less than for the upper population at the lower site (7.23 grams per square meter). Similarly, shoot biomass for the lower population at the upper site (2.12 grams per square meter) was significantly less than for the upper population at the upper site (7.31 grams per square meter). Percent cover showed the same pattern as shoot biomass except that the lower population had significantly greater cover at the lower site (25.8 %) than at the upper site (11.7 %). Shoot nitrogen was measured on dry shoot material gathered at the end of the growing season. There was no significant difference in shoot nitrogen between populations at either site. Reproductive effort (culms per square meter) was zero for the lower population at the upper site and was 10.3 at the lower site. There was no significant difference between sites in the culm density of the upper populations. There is no effect of climate change on the upper population of P. sandbergii while the lower population had reduced reproductive capacity and percent cover. The effects on the lower populations at the upper site suggest that these populations are negatively affected by exposure to a cooler and wetter climate.

Keywords: climate change, biomass, cover

This abstract is being presented at: 3:30 PM in session:
CLIMATE CHANGE