Abundance and Diversity of Insects in Coastal Grasslands (Fiscalini Ranch Preserve and Rancho Marino Reserve)
Site description
The study was carried out over three days between August 30th, 2016 and September 1st 2016, in two sites in Cambria, San Luis Obispo County, California.
Site one: Kenneth Norris Rancho Marino Reserve, located on the southern edge of Cambria. The reserve contains remnant coastal grasslands, consisting of areas that were cultivated and planted with Harding Grass (Phalaris aquatica), as well as those that have never been cultivated. The entire reserve has been grazed by livestock. Transect one is located in a previously cultivated planted area, transect two is located in an uncultivated area.
Site two: Fiscalini Ranch Preserve is a coastal grassland located within the edges of Cambria town. The preserve has been grazed in the past by livestock but not cultivated. The reserve is no longer grazed and now functions as a nature reserve
Methods
Two 100m transects were laid out at site one and two. A total of 18 locations from each transect were sampled, six per day. The sampling locations were chosen by generating 25 random numbers between 1 and 100. The daily sites were chosen by generating six random numbers between 1 and 25 to correspond with the position on the original random number list. These final numbers were used to indicate the distance from the start of the transect.
At Rancho Marino, transect 1 was located at 35.53966, -121.09032 to 35.53896, -121.08968. Transect 2 was located at 35.52933, -121.07793 to 35.52862 , -121.07728. At Fiscalini transect 1 35.54944, -121.10043 to 35.55009, -121.10102. Transect 2 is from 35.55046, -121.10166 to 35.55117, -121.10227.
Polaroid Cube cameras were used to capture visits by both flying and crawling insects. The cameras were placed six steps away from the transect northwards at each of six sampling distances. The cameras faced north to minimize interference from solar glare. The first hour of video was reviewed and each instance of an insect entering the field of view was recorded. Insects that left the field of view and returned were counted as two separate observations because it was not possible to confirm the identity of an individual.
Pan traps were used to sample the insect communities. The pan traps were made from white Solo bowls painted red, blue, yellow or left unpainted. The bowls were filled with an unscented dish detergent solution. The pan traps were placed at each of the six camera locations on each transect in the following order: red, white, yellow, blue with respect to the camera’s field of view. Pan traps were left out for three hours (on average 12:30 - 15:30). After collection, the insects were stored in 95% ethanol. Bees were identified to family at a minimum and genus where possible. The remaining insects were identified to order.
To assess vegetation cover, 0.25 m2 quadrat was used to visually estimate the proportion of Harding grass, other exotics, native plants and bare ground at each sampling location and the presence/absence of scat was recorded. Any insects observed during the vegetation survey were recorded.
