Post-doctoral researcher, Johansen lab
Degrees: Diploma of Geography, University of Leipzig
M.S. in Biology, John Carroll University
Ph.D. in Soil and Water Sciences, University of California-Riverside
Expertise:  Desert ecology, soil ecology, biological soil crusts, biogeomorphology

Research Interests

My overall research objective is to understand links between the morphology and characteristics of desert landscapes and their associated soils, vegetation and microbial communities. Specifically, I am interested in elucidating factors that impact community composition, ecology, and ecophysiology of biological soil crusts in landscapes of the Mojave and Sonoran Desert as well as the California Chaparral.

Recent Courses

PH 115/115L Environmental Earth Science (co-taught with Dr. Johansen)
PH 206 Earth System Science


Pietrasiak, N., Mühlsteinová, R., Siegesmund, M. & Johansen, J.R. in review. Phylogenetic placement of Symplocastrum (Phormidiaceae, Cyanobacteria) with descriptions of two new species: S. flechtnerii and S. torsivum. Phycologia,

Osorio-Santos, K., Pietrasiak, N., Bohunická, M., Miscoe, L.H., Kovácik, L., Martin, M.P. & Johansen, J.R. in review. Seven new species of Oculatella (Pseudanabaenales, Cyanobacteria). European Journal of Phycology,

Patzelt, D.J., Hodač, L., Friedl, T., Pietrasiak, N. & Johansen, J.R. in review. Biodiversity of soil cyanobacteria in the hyper-arid Atacama Desert, Chile, assessed by culture dependent and independent approaches. Journal of Phycology,

Mühlsteinova, R., Johansen, J.R., Pietrasiak, N., Martin, M.P., Osorio-Santos, K. & Warren, S.D. 2014. Polyphasic characterization of Trichocoleus desertorum sp. nov. (Pseudanabaenales, Cyanobacteria) from desert soils and phylogenetic placement of the genus Trichocoleus. Phytotaxa, 193: 241-261.

Mühlsteinova, R., Johansen, J.R., Pietrasiak, N. & Martin, M.P. 2014. Polyphasic characterization of Kastovskia adunca gen. et comb. nov. (Oscillatoriales, Cyanobacteria) from desert soils of the Atacama Desert, Chile. Phytotaxa, 193: 216-228.

Pietrasiak, N. & Johansen, J.R. 2014. Microbiotic soil crust communities in California’s deserts are ecologically critical. Fremontia 42: 18-19.

Pietrasiak, N., Drenovsky, R.E., Santiago, L.S., & Graham, R.C. 2014. Biogeomorphology of a Mojave Desert Landscape – configurations and feedbacks of abiotic and biotic land surfaces during landform evolution. Geomorphology, 206: 23-36.

Pietrasiak, N., Regus, J.U., Johansen, J.R., Lam, D., Sachs, J.L. & Santiago, L.S. 2013. Biological soil crust community types differ in key ecological functions. Soil Biology and Biochemistry, 65: 168-171.

Martínez-Berdeja, A., Pietrasiak, N., Tamase, A., Ezcurra, E. & Allen, E.B. 2013. Living where others dare not: Microhabitat distribution and seed retention in Chorizanthe rigida, a basicarpic desert annual. Journal of Arid Environments, 97: 120-126.

Flechtner, V.R., Pietrasiak, N. & Lewis, L.A. 2013. Newly revealed diversity of eukaryotic algae from wilderness areas of Joshua Tree National Park (JTNP). Monographs of the Western North American Naturalist, 6: 43-63.

Pietrasiak, N., Johansen, J.R., La Doux, T. & Graham, R.C. 2011. Spatial distribution and comparison of disturbance impacts to microbiotic soil crust in the Little San Bernardino Mountains of Joshua Tree National Park, California. Western North American Naturalist, 71:539-552.

Pietrasiak, N., Johansen, J.R. & Drenovsky, R.E. 2011. Geologic composition influences distribution of microbiotic crusts in the Mojave and Colorado Deserts at the regional scale. Soil Biology and Biochemistry, 43: 967-974.