Abstract Detail


Haynes, Audrey [1].

Presence of N-fixing neighbors increases leaf N and water use efficiency in Castilleja applegatei, a root hemiparasite.

Parasitic plants are known for their high transpiration rates and low water use efficiency (WUE), which the N-parasitism hypothesis posits is driven by N limitation. Thus, availability of N-fixing hosts may affect parasite’s WUE and in turn impact the surrounding plant community. Here, I investigate how the availability of an N-fixing host affects the root hemiparasite, Castilleja applegatei, and examine host-mediated effects on community structure and soil moisture.
I surveyed plant diversity and percent cover, and measured soil moisture in 120 1x1m plots within Sagehen Experimental Forest, CA. Fifty percent included C. applegatei. In a subset of plots, I measured leaf N, C/N, δ13C, δ15N in C. applegatei, Ceanothus prostratus (a N-fixer), and two non-N-fixing plants (Artemisia tridentata and Wyethia mollis).
Key results
In C. applegatei availability of N-fixing hosts corresponded to a significant increase in leaf %N, a distinct δ15N signature, and an increase in WUE (signified by δ13C). The presence of parasites was associated with a significant decrease in WUE in N-fixing neighbors, but had no effect on the two non-N-fixing species. The presence of parasites significantly affected soil moisture but did not impact diversity or percent cover. 
For C. applegatei higher N availability increases WUE and in turn affects soil moisture, but not plant community structure. These results broadly support the N-parasitism hypothesis and indicate that host type can affect parasite’s physiology and downstream effects.

1 - University of California Berkeley, Integrative Biology, Berkeley, CA, 94720, United States

Artemisia tridentata
Ceanothus prostratus
host-mediated effects
parasitic plant
stable isotope ecology
leaf δ13C
leaf δ15N

Presentation Type: Poster
Session: P, Ecology Posters
Location: Virtual/Virtual
Date: Tuesday, July 28th, 2020
Time: 5:00 PM Time and date to be determined
Number: PEC018
Abstract ID:189
Candidate for Awards:None

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