Date of Award:

2004

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Wildland Resources

Advisor/Chair:

N/A

Abstract

A series of experiments evaluated: 1) the influence of seed intake and gut

retention time on seed passage , recovery , and germinability; 2) fecal seeding and

broadcast /trampling as techniques to incorporate seeds into a well-established

Agropyron desertorum (Fisch.) Schult. stand in Skull Valley , Utah; 3) intensive

grazing as a means to reduce Agropyron biomass and increase establishment and

survival of seeded species; and 4) the recovery and germinability of seed extracted

from dung collected from the field. Two shrubs (Artemisia tridentata Nutt. ssp.

wyomingensis Beetle & Young and Atriplex confertifolia Torr. & Frem.), a grass

(Elymus elymoides (Raf.) Swezey) , and a forb (Sphaeralcea grossulariaefolia (H. &

A.) Rydb.) were selected as representative native species. Holstein heifers were fed

15,000 , 30 ,000 , and 60,000 seeds of Artemisia , Sphaeralcea, and Elymus. Elymus

recovery was negatively correlated to seed intake. Sphaeralcea had the highest

percentage of recovered, undamaged seed, followed by Elymus and Artemisia.

Sphaeralcea and Artemisia seed passage was highest on Day 1 then dropped sharply.

Elymus passage and recovery were more consistent through time. Post-passage

germjnability was highest for Elymus and Sphaeralcea on Day 1. Artemisia

germjnation was neghgible.

In the fall seeding, Sphaeralcea emerged in 6% of the subplots (half were

volunteers). Overall seedling mortality was 93%. Elymus emerged in 63% of the

dung pats, with 86% mortality. No Artemisia emerged. Drought and Anabrus

simplex herbivory contributed to low seedling emergence and survival. In April

2003, similar treatments were applied, except Atriplex seed was substituted for

Artemisia, and a third treatment was added (broadcast seeding/raking). No

emergence was observed. Sphaeralcea had the highest seed recovery from dung

collected in the field trials, followed by Elymus, Atriplex, and Artemisia.

Sphaeralcea germinability was similar for seeds collected from both trials (11 %) and

Elymus germination was highest in the fall seeding (13%).

These studies indicate that: 1) physical seed properties (size, shape, density,

seed coat) influence seed passage , recovery, and germination; 2) intensive grazing

can reduce Agropyron biomass by 50% for 2 years; 3) broadcast/trampling may be

effective for Sphaeralcea; and 4) an average-sized dung pat (714 g) may have ample

germinable Sphaeralcea and Elymus seeds for plant establishment.

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