Effect of Phalaris aquatica on the abundance and diversity of vertebrate animals in Mediterranean coastal grasslands in California

Abstract

Harding grass (Phalaris aquatica), an invasive non-native species of bunchgrass, has been introduced to grasslands in many regions of California, particularly those with a history of disturbance, such as tilling and grazing. Due do the invasive nature of Harding grass, we sought to examine whether it has an effect on small animal abundance and diversity in the grasslands, Rancho Marino Reserve (RM) and Fiscalini Ranch Preserve (FR) in California. Both grasslands have similar climate and geographic location but differ in management history. Two transects were created in each site, with eight plots per transect. Animal cameras were deployed over the course of three nights to examine the abundance and diversity of small animals. Due to the history of tilling and planting of RM, and its increase in P. aquatica coverage, there was less animal abundance and diversity compared to FR. The results indicated that the untilled/unplanted areas had more animal abundance and diversity compared to tilled/planted due to the lack of Harding Grass. This can be due to factors such as diminished soil quality, difficulty in maneuvering in the tall grass, and adaptability to native vegetative state. Invasive plants have the ability to increase rapidly in space and potentially lead to ecosystem degradation. This adds further knowledge in the relationship between small animals and their habitats and helps conservation biologists ensure mammalian populations remain stable.