INTRASPECIFIC VARIATION IN SANDBERG BLUEGRASS (POA SECUNDA)’S RESISTANCE TO ANNUAL GRASS INVASION
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Date
2021-06
Authors
Cook, Emily
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oregon
Abstract
Exotic 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.
Description
16 pages
Keywords
cheatgrass (Bromus tectorum), invasive species, Native grass species, Restoration