California State University Bakersfield


Welcome to the Webpage of

Dr. Anna L. Jacobsen


Plant Ecology and Evolutionary Biology

Plant Structure-Function



Dr Anna Jacobsen with krumholtz tree


Dr. Jacobsen's Homepage    Jacobsen Lab Research Methods Page    Jacobsen Lab Publications


If you are a current or prospective CSUB biology student interested in working in Dr. Jacobsen's lab, please stop by her office or email to set up an appointment to discuss your research interests.  There are opportunities for both undergraduate and graduate students to participate in research! 



Current lab members:


Jaycie Fickle (undergraduate)


Jackeline Medina Arreguin (undergraduate)


Catherine Sanchez (undergraduate)


Jessica Valdovinos-Ayala (laboratory technician)


Alex Baer (graduate) (CSUB Student Research Scholars Program 2016-2017)


Marta Percolla (graduate) (CSUB CREST fellow 2016-2018)



The Jacobsen lab in summer 2016 working to carefully excavate an intact long poplar root from a juvenile tree in our on-campus research plot:

Dr. Jacobsen, Marta, Jessica, Jackie, Jaycie, Catherine, Daniela, Emily, Alex (from foreground to background).



The combined Jacobsen and Pratt labs in January 2014:

Daniela, Marta, Justin, Courtney, Sam, Dr. Pratt, Dr. Jacobsen, Dr. Venturas (post-doc), Evan, Hayden, Jessica



Past lab members:



Jesica Gonzalez

Lawrence Ignacio

Shana Carey

Mark Bersentes (CSUB Student Research Scholars Program 2011-2012)

Tamani Gause

Mark De Guzman

Marta Percolla (CSUB Student Research Scholars Program 2012-2013, Botanical Society of America Physiological Section Student Best Student Poster 2013)

Raeanne Quaresma

Aaron Ramirez

F. Daniela Rodriguez-Zaccaro (CSUB Outstanding Graduate in the College of Natural Sciences, Mathematics and Engineering 2016, CSUB Student Research Program Poster Competition 3rd Place University-wide Undergraduate Winner 2015)

Hayden Toschi

Gilberto Uribe

Jessica Valdovinos-Ayala (Ecological Society of America Physiological Ecology Section Student Travel Award 2015)

Alanisha Woods





Robert Atwood (committee)

Genetic variation among populations of the Bakersfield cactus Opuntia basilaris var. treleasei, based on amplified fragment length polymorphisms.

Spring 2012


Heather Keldgord (committee)

The distribution of sexes across a rainfall gradient in a subdioecious southern Californa chaparral shrub Rhus ovata S. Watson (Anacardiaceae).

Summer 2012


Evan MacKinnon (co-advisor)

(CSUB School of Natural Sciences, Mathematics, & Engineering Outstanding Graduate Thesis 2013)

A trait-based approach to restoring southern California habitats invaded by the Mediterranean grass Bromus madritensis ssp. rubens (Poaceae).

Spring 2013


Justin Martinez (advisor)

(CSUB Student Research Scholars Program 2013-2014, CSUB Graduate Student Research and Scholarship Initiative 2013-2014)


Courtney Traugh (committee)

Stem and root xylem trade-offs in carbohydrate storage, water stress tolerance, and biomechanics or sprouting and non-sprouting chaparral species.

Summer 2012



Post-doctoral researchers:


Dr. Martin Venturas (2014-2015)



High school students (REVS-UP Program):


Summer 2015

Daisy Buenrostro

Viviana Firo

Brooke Herrera


Summer 2014

Ryan Romero

Jackie Lopez

Estevan Ramirez (teacher)



Some of our current lab research topics/projects include:

Examining xylem vessel network structure and function in woody plants using developmental and intra-organismal systems (NSF IOS-1252232)

Plant hydraulic structure and function


Grapevine hydraulics

Fire ecology of Mediterranean-type climate region shrubs

Community convergence among arid and semi-arid shrublands in Mediterranean-type climate regions


Plant Structure-Function

Plants transport water through specialized water transport cells. In flowering plants, these cells, called vessel elements, combine to form long multi-cellular jointed tubes termed xylem vessels.  In the Jacobsen lab, we are working to understand the structure of these vessels at the cellular-level and at the tissue-level.  We are particularly interested in examining the structure of the three-dimensional vessel network of woody plants (i.e. how vessels develop and connect with one another throughout the tissues of a plant).  Additionally, we are examining how vessel structure relates to the hydraulic function of plants.

Vessels have three-dimensional structure, including significant curvature of vessels and significant changes in diameter of vessels (even along the length of a single vessel). Species can vary greatly in the interconnectedness of the vessel network and the density and structure of pitting between adjacent vessels. Work in our lab to examine inter- and intra-specific patterns in vessel length has yielded particularly interesting and exciting results, especially since this trait has sometimes been called the "neglected dimension" of vessel structure!

Many students in the lab have conducted research or are continuing to conduct research examining vessel structural traits, including measuring vessel pit traits, vessel diameter, vessel length, and connectivity of the vessel network.  As a lab, we are working to combine data from different levels of xylem organization (cellular to tissue) to develop a model of the vessel network.  We are also working to quantify other elements of xylem structure, such as fiber and parenchyma cell structure and abundance. 

Raeanne Q completing anatomy measures Alanisha working in the lab Mark B loves anatomy Tamani with a vessel picture

Marta with her student research scholars poster Hayden measuring pit area Jessica measuring vessel diameter distributions Jesica Gonzalez sectioning xylem samples


Nearly all of the research projects in the lab are based on the broad idea of how plants use and move water, especially in response to stress.  Thus, all of the research projects in the lab are measuring plant hydraulic function in some way.  The most common measures of plant hydraulic function that are completed in the lab include measures of xylem resistance to water stress induced cavitation and measures of hydraulic conductivity (transport efficiency).  Additional information about our methods for these measures may be found here.

Evan M processing stems in the lab Martin measuring water potentials Daniela in the hydraulics lab

Justin at the Student Research Scholars Poster contest 2014


Fire Ecology and Community Convergence of Mediterranean-type Climate Region Shrublands

Much of the research conducted in the Jacobsen lab has focused on investigation of shrub communities from Mediterranean-type climate regions.  There are five Mediterranean-type climate regions globally that are dominated by evergreen, tough-leaved shrub species. 

The evergreen shrubs in these regions respond to fire by resprouting from modified root structures, recruiting through fire-cued seed germination, or through a combination of these strategies.  We are currently investigating hypotheses related to how the xylem structure of resprouting plants relates to differential recovery of species post-fire, including why some species tend to suffer massive mortality during the first few years of post-fire recovery while other species are more resilient. 

Additionally, fire can have a profound effect on community composition of Mediterranean-type shrub communities.  Dr. Jacobsen is currently involved in several long-term collaborative research projects investigating plant species and community response to fire, particularly in response to additional stresses such as heavy browse or drought.  This work is being conducted at field sites in several locations throughout southern California, including the San Gabriel and Santa Monica Mountains, as well as on Santa Catalina Island off the coast of Los Angeles, California, and in the Western Cape Region of South Africa.  This work involves collaboration with many other researchers and several undergraduate and graduate students. 

Gilbert and Aaron at a post-fire chaparral site DeGuzman, Jacobsen, Uribe, and Traugh after working at postfire field site Esler, Pratt, and Marain at a postfire site in Paarl, South Africa



Much of Dr. Jacobsen's work investigating plant hydraulic function has been completed in close collaboration with Dr. R. Brandon Pratt, who is also a member of the CSUB Department of Biology.  Dr. Pratt has additional information about these research projects on his website.  Additionally, our lab has recently collaborated with or continues to collaborate with the following individuals and labs in our investigations of plant hydraulic structure and function: Dr. Uwe Hacke of the University of Alberta, Dr. Frank Ewers of California State Polytechnic University, Pomona, Dr. Stephen Davis of Pepperdine University, and Dr. Karen Esler of Stellenbosch University.


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