Endangered Species Recovery Program

Progress report on 1994 grazing studies for
Kern mallow and San Joaquin woolly-threads

Unpublished Report

Bureau of Land Management
Bakersfield, CA, 22 pp.
1994

by

Ellen A. Cypher

Abstract

Pilot studies were initiated to evaluate the effects of livestock grazing on the endangered, annual plant species Kern mallow (Eremalche kernensis) and San Joaquin woolly-threads (Lembertia congdonii), and to identify patterns of plant survival, growth, and reproduction related to existing conditions in one population of each species. To protect selected plots from grazing, 23 and 20 exclosures, respectively, were constructed in the study areas for Kern mallow and San Joaquin woolly-threads. Demographics of Kern mallow and San Joaquin woolly-threads will compared between paired ungrazed (inside exclosures) and grazed (outside exclosures) plots during 1995. The Kern mallow study site, in the Lokern area of Kern County, was not grazed during the study period but was in an area historically grazed by sheep. In 1994 Kern mallow survival was inversely related to the amount of mulch (residual dry matter) present. A significantly higher percentage of Kern mallow plants survived to flowering in the northwest quarter of the study area, where the herbaceous vegetation was less dense, shrubs were more dense, and native species were more prevalent, than in the southeast quarter. However, flower production per plant did not differ between the two sites. Appropriately-managed sheep grazing may benefit Kern mallow survival in densely-vegetated habitats by reducing competition and decreasing mulch cover. Cattle were present at the San Joaquin woolly-threads study site on the Carrizo Plain in San Luis Obispo County from December 1993 through March 1994. In spring 1994, data were collected at varying distances from a water trough which corresponded to differing grazing intensities. Size and reproduction of San Joaquin woolly-threads were affected by both cattle use and by activity of giant kangaroo rats (Dipodomys ingens). Stem lengths and flower production were not related to distance from the water trough for plants growing on giant kangaroo rat precincts (burrow systems). However, for San Joaquin woolly-threads occurring off precincts, stem lengths were directly* related to distance from the trough. The effect of location on giant kangaroo rat precincts was much more pronounced than that of cattle grazing. Individual San Joaquin woolly-threads occurred most often on precincts, where they matured faster and grew larger than plants off precincts. Unlike Kern mallow, occurrence of San Joaquin woolly-threads was not related to associated vegetation.