The National Park Service initiated a backcountry campsite restoration project
in 1987 to restore native vegetation on severely degraded campsites in three subalpine
lake basins in Yosemite National Park. Restoration treatments included soil
scarification, transplanting, manual seeding and site protection. Eight of the treated
campsites were monitored in 1990 to evaluate changes in percent vegetation cover,
species richness and volunteer establishment that had occurred over the three year
period beginning prior to treatment application in the summer of 1987, and ending in
the summer of 1990.
Percent vegetation cover increased slightly across all sampled quadrats ([mean] =
0.71; N = 214) with mean percent cover changes ranging from -0.37 to 4.36 on
individual campsites. Three sites had a loss of cover. Percent cover changes differed
most among campsites within lake basins. Changes in percent cover did not differ
among lake basins or impact strata (barren core, moderately trampled, and
peripheral). Transplanting did not appear to be an important influence on changes in
percent cover, as cover changes did not differ between planted and unplanted areas.
Survival of transplants planted in 1987 was poor (19.2%), but survival of transplants
planted in 1988 was higher (70.5%).
Species richness increased slightly across all sampled quadrats ([mean] = 0.54
species per quadrat), with species richness changes on campsites ranging from -0.13
to 1.75 species per quadrat. One site had a mean decrease in species richness.
Species richness changes differed among campsites, with the largest increases
occurring on those campsites that also had the greatest increases in percent cover.
Changes in species richness also differed among impact strata, with the largest
increases occurring on barren core areas. There were small differences among lake
basins, and species richness changes did not differ between planted and unplanted
areas.
Volunteer establishment occurred on all treated sites. The number of
volunteers per site ranged from one to 45, and 29 species were represented.
Individual quadrats had from one to four volunteers. Approximately 50% of the
volunteers were producing seed, and overall vigor among volunteers was good.
Numbers of volunteers per quadrat differed most strongly among campsites. Slight
differences were detected among lake basins and impact strata, with numbers
decreasing from barren core to peripheral quadrats. Differences in numbers of
volunteers per quadrat between planted and unplanted areas were not detected.
Soil scarification may enhance increases in cover, species richness and
numbers of volunteers. However, the influence of scarification was tested on two
sites only, and further study is recommended.
The recovery process appeared to be strongly affected by factors operating at
the campsite level. For example, sites with the greatest increases in percent cover
also had the greatest increases in species richness and the most volunteers. These
sites had coarse soils, relatively abundant sunlight and moisture, and were effectively
protected from trampling after site treatment. Results indicate revegetation
prescriptions should be made on a site-by-site basis.
The performances of eleven species used in transplanting or occurring as
volunteers were evaluated. Five species, Agrostis humilis, Calamagrostis breweri,
Muhlenbergia filifonnis, Trisetum spicatum, and Calyptridium umbellatum show
potential as colonizers in unassisted revegetation and may be useful in manual seeding
treatments; three species, Calamagrostis breweri, Carex rossii, and Juncus panyi
show potential for transplanting and nursery propagation; and two species, Carex
spectabilis and Carex straminiformis, require further study to determine their
effectiveness in subalpine revegetation treatments. / Graduation date: 1993
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/36353 |
| Date | 27 April 1992 |
| Creators | Moritsch, Barbara J. |
| Contributors | Muir, Patricia S. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
Page generated in 0.0021 seconds