Date of Award


Document Type


Degree Name

Master of Science (MS)

Program Name

Environmental Policy and Management

Capstone Instructor

Dr. Elizabeth D'Andrea


Non-native invasive weeds have exploded throughout northern Sierra Nevada recently, coinciding with extraordinary drought conditions. Their presences are affronting local ecosystem structure, function, and biodiversity by outcompeting native plant communities. This paper explores the correlations between recent drought conditions in northern Sierra Nevada and the increased presence of three non-native invasive weed species in Nevada County, California -- Carduus nutans (musk thistle), Centaurea stoebe (spotted knapweed), and Chondrilla juncea (rush skeletonweed). This study utilizes Pearson’s product-moment correlation coefficient to quantify covariance between the numbers of observed infestation sites of these three species and decreased precipitation, increased temperatures, and total snowfall amounts. Results show observations of these species positively correlate with increased temperatures, and negatively correlate with precipitation departures from normal and reduced total snowfall amounts, over 15-year and 6-year timeframes. This correlative analysis serves to advance invasion ecology’s understanding of the complex relationships between regional climatic changes and non-native plant species invasions.



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