Title

Palouse Prairie Restoration in Eastern Washington: First-year Plant Cover and Richness Driven by Topographic Variation, Not Seed Mix Diversity

Faculty Mentor

Rebecca Brown

Document Type

Oral Presentation

Start Date

10-5-2023 11:10 AM

End Date

10-5-2023 11:30 AM

Location

PUB 319

Department

Biology

Abstract

With over 99.99% of Palouse prairie lost, regional ecosystem function hinges on restoring native prairie. Little research exists on seed-based Palouse prairie restoration compared to other North American steppes, hindering regional efforts. To test the hypotheses that increasing seed blend diversity would increase native plant cover and species richness and decrease non-native plant cover and richness, with each factor also being influenced by topography, we used a randomized-block design to drill-seed 3 blends into 24 5.6 x 200 m strips on 15 acres of EWU’s Prairie Restoration Project in Cheney, Washington in October 2021. Each strip contained 6 1-m2 plots, totaling 144. plots Treatments included 6 bunchgrass species, 6 bunchgrasses with 8 forb species, and 6 bunchgrasses with 15 forb species. In June 2022, we recorded each plot’s species percent cover. We compared species cover and richness and community composition for each treatment across three aspects: hilltop/south, north, and swale using mixed linear models. Diversity and topography interacted to affect non-native richness, which was lower in swales than north slopes across treatments, but higher in north than top/south in grass-only treatments but similar between top/south and swales. Our hypothesis that blend diversity influences native and non-native richness and cover was not supported. Topography imparted large effects, with swales and north slopes having lower native richness and cover and higher non-native cover than top/south. Our results indicate (1) Palouse prairie blend designs should consider topographic variation and (2) increasing blend diversity doesn’t provide first-year advantages but interacts with topography to affect community composition.

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May 10th, 11:10 AM May 10th, 11:30 AM

Palouse Prairie Restoration in Eastern Washington: First-year Plant Cover and Richness Driven by Topographic Variation, Not Seed Mix Diversity

PUB 319

With over 99.99% of Palouse prairie lost, regional ecosystem function hinges on restoring native prairie. Little research exists on seed-based Palouse prairie restoration compared to other North American steppes, hindering regional efforts. To test the hypotheses that increasing seed blend diversity would increase native plant cover and species richness and decrease non-native plant cover and richness, with each factor also being influenced by topography, we used a randomized-block design to drill-seed 3 blends into 24 5.6 x 200 m strips on 15 acres of EWU’s Prairie Restoration Project in Cheney, Washington in October 2021. Each strip contained 6 1-m2 plots, totaling 144. plots Treatments included 6 bunchgrass species, 6 bunchgrasses with 8 forb species, and 6 bunchgrasses with 15 forb species. In June 2022, we recorded each plot’s species percent cover. We compared species cover and richness and community composition for each treatment across three aspects: hilltop/south, north, and swale using mixed linear models. Diversity and topography interacted to affect non-native richness, which was lower in swales than north slopes across treatments, but higher in north than top/south in grass-only treatments but similar between top/south and swales. Our hypothesis that blend diversity influences native and non-native richness and cover was not supported. Topography imparted large effects, with swales and north slopes having lower native richness and cover and higher non-native cover than top/south. Our results indicate (1) Palouse prairie blend designs should consider topographic variation and (2) increasing blend diversity doesn’t provide first-year advantages but interacts with topography to affect community composition.