The projected effects of climate change on plant species distributions in tallgrass prairies of Iowa

Background/Question/Methods

Future climate trends in Iowa are expected to be highly variable, with increased temperatures and more variable rain events, leading to an increased probability of drought. These changing conditions may challenge the survival and viability of plant species, altering the composition of grassland communities. Such changes could have significant effects on the value of these grasslands for grazing, biodiversity, and other ecosystem services. We examined the potential effect of climate change on the area of suitable habitat for 15 common plant species (including forbs, warm-season grasses, cool-season grasses and exotic species) of Iowa tallgrass prairies to assess 1) the extent of current habitat still suitable in future periods and 2) changes in overall area of distribution. We used the A1F1 fossil intensive climate scenario for 2040 and 2080 future time periods. Several derived bioclimatic variables considered critical to plant physiological function were used to build our models. Binary species distribution maps were created to display areas that are 1) currently suitable, 2) currently unsuitable, and 3) areas of original habitat still considered as suitable in future time frames. From these distribution maps, percent change in habitat suitability was calculated under each time frame and for each species.

Results/Conclusions

Under the A1F1 scenario, the 2080 time frame shows the greatest overall number of species exhibiting reductions in range, with 40% of species predicted to show negative trends. About half of those species are forbs. Only two species of warm-season grasses are projected to show no overall range change across both time frames. Projections to 2040 show range expansion for cool-season grasses, and this trend continues through 2080. Exotic cool-season grasses such as tall fescue (Lolium arundinaceum) are highly invasive and have the potential to out-compete native plant species, thus changing the overall composition of Iowa’s tallgrass prairies. Understanding how climate is changing and its potential impact on species distributions is valuable to conservation efforts aimed at restoring native tallgrass prairie. Results from this project will help guide conservation and future management of these grasslands and assist landowners in determining how to respond and adapt to climate change.