Journal
ECOLOGY
Volume 91, Issue 1, Pages 141-154Publisher
WILEY
DOI: 10.1890/08-1446.1
Keywords
Artemisia tridentata; Bromus tectorum; California, USA; facilitation; Great Basin Desert; invasive species; life table response experiment; loop analysis; LTRE; periodic matrix models; positive interactions; Purshia tridentata
Categories
Funding
- TEPS Institute
- UCSC Environmental Studies, Department
- Mildred E. Mathias Graduate Student Research Grant
- Valentine Eastern Sierra Reserve Graduate Student Research Grant
- David Gaines Memorial Award
- California Native Plant Society
Ask authors/readers for more resources
There is increasing recognition that overall interactions among plant species are often the net result of both positive and negative effects. However, the positive influence other plants has rarely been examined using detailed demographic methods, which are useful for partitioning net effects at the population level into positive and/or negative effects oil individual vital rates. This study examines the influence of microhabitats created by the native shrubs Artemisia tridentata and Purshia tridentata on the demography of the invasive annual grass Bromus tectorum in the Great Basin Desert, California, USA. Shrub understory environments differed significantly from intershrub space and were characterized by higher soil fertility and less extreme microclimates. There existed a strong spatial association between B. tectorum and the shrubs across four years, with more than double the density of B. tectorum in shrub microhabitats compared to intershrub space. Periodic matrix models were used to calculate population growth (lambda) and reproductive potential (RP, expected lifetime fecundity of seedlings) of B. tectorum in different microhabitats over two years. Modeled population growth was significantly increased in shrub microhabitats in the first of two years. This was primarily due to increased seedling establishment in Artemisia microhabitats. rather than effects during the growing season. In the following year, B. tectorum individuals in shrub microhabitats had a significantly greater reproductive potential than those in intershrub microhabitats, indicating shrub facilitation during the growing season. Loop analysis revealed an interacting effect of year and microhabitat on B. tectorum life history pathway elasticity values, demonstrating a fundamental influence of spatiotemporal factors oil which life history pathways are important and/or possible. Life table response experiment (LTRE) analysis showed that increased survival and growth rates positively contributed to population growth in both years Under Purshia, but only in the second Year Under Artemisia. This research provides evidence that the positive effects of native shrubs on B. tectorum can be strong enough to produce net positive effects at the population level, although positive effects were variable. In this study, a rigorous demographic approach was particularly useful in partitioning overall interactions into positive and negative components.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available