Publication Date

Summer 2013

Degree Type

Thesis

Degree Name

Master of Arts (MA)

Department

Geography

Advisor

Richard Taketa

Keywords

biological invasions, exotic species, invasive plants, Maxent, species distribution modeling, vegetation

Subject Areas

Geography; Natural resource management; Conservation biology

Abstract

Early detection of an invasive species facilitates control and eradication. Slender false brome (Brachypodium sylvaticum) was first discovered in the Santa Cruz Mountains of Central California in 2003 as a non-native grass in redwood forests, competing with native vegetation. The current infestation in the Santa Cruz Mountains, estimated to be 300 acres, is concentrated in San Mateo County and could be eradicated. This study sought to determine most likely locations of slender false brome in the Santa Cruz Mountains by assessing environmental attributes of known presence locations using species distribution modeling and Maxent software. The study used 1,320 species presence points collected in field surveys conducted from 2009 to 2012, GIS environmental layers covering a 940 km² study area, and the machine-learning program Maxent to identify slender false brome habitat at a 30 m resolution in the Santa Cruz Mountains. Maxent models successfully identified locations of potential distribution of slender false brome (training AUC = 0.961, test AUC = 0.960). Annual precipitation, average annual maximum or minimum temperature, and soils were the most important predictors. An independent dataset corroborated the performance of the Maxent model. Maxent could be used by land managers for targeting field surveys by predicting most likely B. sylvaticum habitat in the Santa Cruz Mountains.

Download

Share

COinS