Endangered Species Recovery Program

Preliminary report on 1995 Kern mallow and
San Joaquin woolly-threads grazing
and competition reduction studies

Unpublished Report

Bureau of Land Management
Bakersfield, CA, 13 pp.
1996

by

Ellen A. Cypher

Abstract

The effects of grazing and competing vegetation on survival and reproduction of Kern mallow (Eremalche parryi ssp. kernensis) and San Joaquin woolly-threads (Lembertia congdonii) were evaluated in Spring 1995 at the Lokern and Carrizo Plain Natural Areas (CPNA), respectively. Treatments were clipping, mulch removal, and control at Lokern, and clipping, grazing, trampling, and control at the CPNA. Associated vegetation on one set of plots at each site was clipped to 2.5 cm in late January and again in early February, leaving the endangered plants intact. Mulch was removed with forceps in January. The CPNA study site was grazed from 1 December through 30 April, during which time plots adjacent to exclosure fences also were trampled. The proportion of Kern mallow seedlings surviving to reproduction (41.3-56.1%) did not differ significantly among treatments. Average flower production per Kern mallow on clipped plots (24.8) significantly exceeded that on mulch-removal (13.8) and control plots (17.0). Height, cover, and biomass of associated vegetation at the end of the growing season did not differ among treatments. Survival of San Joaquin woolly-threads seedlings on clipped plots (56.3%) was significantly greater than on grazed (32.0%) and trampled (30.0%) plots but did not differ from controls (47.7%). Mean flower head production of San Joaquin woolly-threads did not differ significantly among treatments but was highest on clipped plots (20.4) and lowest on control plots (13.2). Grazing significantly reduced the height of associated vegetation, but not the cover or biomass. Giant kangaroo rat precincts did not affect survival or reproduction of San Joaquin woolly-threads in 1995 but did promote growth of associated vegetation. The net effect of competition reduction for both Kern mallow and San Joaquin woolly-threads was beneficial even though vegetation was clipped early in the growing season. Grazing may be detrimental if it continues into the flowering period of the endangered plants. Strategies are needed to reduce competition without reducing survival or fecundity of Kern mallow and San Joaquin woolly-threads.