COS 118-7 - Topographic variation in grassland community flowering time

Wednesday, August 9, 2017: 3:40 PM
B115, Oregon Convention Center
Rachael L. Olliff Yang, Integrative Biology, University of California Berkeley, Berkeley, CA

Managing a system to provide sufficient floral resources across time is a goal now being

incorporated into climate-smart conservation planning. In this study I examine the

potential to use the variation in climate across topographic gradients to achieve this goal.

Flowering time varies across topography due to differences in abiotic factors.

Idiosyncratic species responses across a landscape may result in phenological differences

within plant communities. In this study I assess forb and grass spring flowering

phenology on north and south aspects at Pepperwood Preserve (Sonoma Co. CA). I

investigate the following questions: 1. Do flowering times differ between aspects? and 2.

Are there differences in the phenological responses to topography based on species,

functional group, or year? To answer these questions I recorded flowering throughout the

spring growing season (March-June) in 2015 and 2016. Thirty 1m2 grassland plots were

located on paired north and south slopes at five locations on the Preserve. Inflorescences

in bud, flower and fruit for all species in the plots were counted weekly to determine start,

peak, and ending dates of each phenological phase, as well as the length of each phase.

Temperature and moisture were also recorded at the plots to define microsite differences.


Results from 2015 and 2016 show that microhabitat is a strong determinant of

phenological timing for many species. Flowering time differed between aspect, with

earlier timing on south facing slopes. In addition, the magnitude of difference between

aspects varied between years and species. Phenological responses to landscape position

resulted in differences in flowering overlap between species. Where increased

complementarity occurred between species, it served to extend the overall community

flowering time. These results suggest that preserving and restoring habitat across

topographic gradients may be a feasible management strategy for extending flowering

phenology to attain climate-smart conservation goals.