Influence of directional side of sagebrush canopies and interspaces on microhabitats

Authors: Davies, Kirk; Copeland, Stella; CLENET, DANIELLE - Oregon State University; Svejcar, Lauren; Bates, Jonathan - Jon

Submitted to: Basic and Applied Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/14/2023
Publication Date: 6/15/2023
Citation: Davies, K.W., Copeland, S.M., Clenet, D.R., Svejcar, L.N., Bates, J.D. 2023. Influence of directional side of sagebrush canopies and interspaces on microhabitats. Basic and Applied Ecology. 72:16-21. https://doi.org/10.1016/j.baae.2023.06.004.
DOI: https://doi.org/10.1016/j.baae.2023.06.004

Interpretive Summary: It is well known that sagebrush create distinct under canopy and between canopy (interspace) microsites that result in microhabitats with different vegetation and ground cover (litter, moss, lichen biocrust, and bare ground) characteristics. However, directional (north and south) side of canopy may also create distinct microhabitats which would promote coexistence and diversity, but it is unknown if microhabitats differ between canopy sides. We investigated vegetation and ground cover characteristics in north and south side canopy microsites and interspace microsites. Several vegetation and most ground cover characteristics varied among north side, south side, and interspace microsites. These results highlight the pivotal role of sagebrush in creating heterogeneity in steppe communities and indicates preventing its loss and restoring it after disturbances should be a management priority. These results are of interest to other scientists and land managers.

Technical Abstract: Shrubs can contribute to spatial heterogeneity in plant communities by creating distinct microsites under their canopies compared to between their canopies (interspaces). This results in distinct microhabitats that differ in understory vegetation characteristics and ground cover. However, microhabitats may also differ under the north and south side of canopies because of differences in shading and other microsite characteristics. We investigated if microhabitats varied among north and south sides of sagebrush, a shrub native to western North America, canopies, and interspaces in 16 plant communities. Several understory vegetation characteristics and most ground cover variables varied among north sides, south sides, and interspaces. Moss and litter cover were greatest and bare ground was lowest in north sides and decreased and increased respectively from north to south sides and from south sides to interspaces. Annual forb and exotic annual grass cover and abundance was less in north side microsites compared to south side and interspace microsites, implying that sagebrush creates heterogeneity in resistance to invasion. This may be critical in allowing native herbaceous vegetation to persist under annual grass invasion pressure. Our results provide strong evidence that sagebrush creates three distinct microhabitats. This highlights the pivotal role of shrubs in creating heterogeneity in shrub steppe communities and indicates that preventing the loss of shrubs in these communities should be a management priority. This also suggests that it is critical to restore sagebrush, and likely other shrubs, after they are lost to maintain differences in microhabitats that promote diversity and coexistence.