INTRASPECIFIC VARIATION IN SANDBERG BLUEGRASS (POA SECUNDA)’S RESISTANCE TO ANNUAL GRASS INVASION

16 pagesExotic species pose a threat to many ecosystems within the western U.S. The annual grass species known as cheatgrass (Bromus tectorum) is a prevailing invader in the Great Basin. Cheatgrass invasion in combination with a change in fire regime and climate exacerbate large fires in the region, contributing to loss of native plant species. Seeding of native perennial grass species has been adopted as a management strategy for post-fire rehabilitation. Native grass species are known to have high variability in traits across climate and space. Knowing this, some populations may be better at resisting invasion to cheatgrass than others. This study explores how water availability and intraspecific variation in traits affects the native Sandburg bluegrass’ (Poa secunda) capacity to resist invasion by cheatgrass. I hypothesize that (1) P. secunda’s resistance to cheatgrass will decline with reduced water availability, but P. secunda populations from warm and arid source environments will have a smaller decline than those from cooler and wetter environment, (2) that the P. secunda populations from warmer, drier areas will be shorter in height, have lower SLA, and higher LDMC and (3) that P. secunda populations with greater trait plasticity will better resist invasion to cheatgrass. Seeds from five populations of P. secunda within the Great Basin were collected and sown in monocultures and in competition with cheatgrass in a greenhouse. I evaluated relationships between several leaf and plant traits with a wet and dry treatment. Significant trait variation was found among populations and between wet and dry treatments. These findings suggest that using seeds that are locally adapted to a restoration area can be beneficial to plant fitness and resistance to invasion. Considering traits connected with disturbance and invasion is valuable to restoration work in the region